How Does P53 Prevents Cancer Formation

How Does P53 Prevents Cancer Formation
Name: Eoghan Miniter
Student ID: 14428052
P53. The guardian of the genome.
The P53 prevents cancer formation by acting as a tumour suppressor gene. Also known as the TP53.
It plays important roles in multicellular organisms by stopping genome mutations. The name p53
was established in 1979 describing the molar mass indicating that it is a 53kDa protein. It was first
discovered in 1979 and was thought to be an oncogene (a gene capable of transforming regular cells
into tumour cells). However in 1989 further research by Bert Vogelstein from John Hopkins School
of medicine discovered that it was actually a tumour suppressor gene. The p53 protein consists of
393 amino acids. This protein can activate other proteins that have the ability to fix
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Transformation-Related Protein 53 Essay
Transformation–Related Protein 53, also known as TP53, is a tumor suppressor gene. It is named
after its molecular mass. The gene was discovered by Arnold Levine, David Lane, and William Old
in 1979 and was voted molecule of the year by science magazine in 1993. Although, it was not until
1989 that it was revealed to be a tumor suppressor gene. It was previously thought of as an
oncogene. TP53 encodes for a protein, called p53 protein, that helps to regulate the cell cycle and
inhibits mutations in the genome as well. Both of these functions help to conserve stability. One of
the reasons for TP53's high importance, and the extensive research on the gene, is its function to
suppress cancer cells in multicellular organisms, including humans (Vijayaraj). The gene is located
on chromosome seventeen (17p13.1). The genomic coordinates are 17:7,571,719–7,590,867 and it is
19,148 base pairs in length. The p53 protein is made up of three hundred and ninety three amino
acids and is considered a phosphoprotein. The gene also contains four domains, also called units.
Each one of these domains has a different responsibility. One domain, called the core domain,
identifies specific DNA sequences. Another domain stimulates transcription factors. The third
domain controls the tetramerization of the protein. The last domain is able to distinguish damaged
DNA. This may include single–stranded DNA or base pairs that are misaligned (Vijayaraj). The
gene also contains twenty

Essay On Hbx X Protein
Hepatitis B virus x protein (HBx) is one of four encoded proteins in the Hepatitis B virus (HBV)
genome. HBx is encoded by the smallest open reading frame of mammalian hepadnaviruses which
produces a 154–amino acid protein with a molecular mass of 17.5 kDa. HBx has defied high–
resolution crystallization and nuclear magnetic resonance so little is known of HBx three–
dimensional structure (an implication that HBx is unstructured). HBx also lacks homology with any
other known protein so there is poor understanding of how it functions. Comparative analysis of
HBx gene sequences from mammalian hepadnaviruses of different species has highlighted areas
where the sequence is highly conserved. This includes predicted helical domains located in the ...
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Research suggests that when HBx interacts with cellular proteins it dimerizes; however, this remains
speculative. Three articles (Gao et al., Elmore et al. and Zhu et al.) have been selected to highlight
some of the key carcinogenic effects of the HBx protein.
MicroRNA–145 (miR–145) expression shows an inhibitory effect on the proliferation of human
cancer cells. In HCC, the expression of miR–145 was found to be significantly downregulated as a
result of HBx interaction. Gao et al. identified Cullin–5 (CUL5) as a target of miR–145. CUL5 has
been reported to be functionally involved in numerous cellular activities including the cell cycle. In
addition, CUL5 was also reported to be involved in regulating apoptosis by modulating the
phosphorylation of mitogen–activated protein kinase (MAPK) and induce p53 mRNA and protein
expression. The substantial increase in the expression of CUL5, due to the inhibition of a miRNA–
145 expression by HBx, results in less phosphorylation of MAPK and therefore less p53 mRNA and
protein expression. This study confirmed a significant decrease in the expression of miRNA–145
and a substantial increase in the mRNA and protein expression of CUL5 in HBx–over–expressing
cells compared with empty vector–transfected cells. The proliferation of the cells transfected with
HBX plasmid markedly increased compared with cells transfected with empty vector.
The p53 tumor suppressor protein is involved in many cellular

P53 Protein Case Study
In the spot assay, p53 mutant T155N was tested for binding by the color it develops. On the high
adenine agar plate, the p53 strains, wild type (wt), mutant T155N (mut), and deletion (del),
produced white cultures with all p53 response element (RE) sites, consensus (con), p21, and BAX.
Therefore, all p53 strains showed transactivation because there was already enough ADE2 protein
on the plate (see Figure 1B). Unlike the high adenine agar plate, the low adenine agar plate showed
significant differences between the p53 strains and the p53 REs. The p53 wt strain developed white
cultures while the p53 deletion strain developed red cultures. The p53 mut strain developed a pink
culture with p53 RE con and red cultures with p53 RE p21 and BAX. In this case, p53 wt shows
transactivation and a high binding affinity with all three p53 REs. Contrarily, the p53 del strain
shows no transactivation and binding affinity with all the p53 ... Show more content on
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If there is no protein activating the response element, then there is no activation of ADE2 to make
ADE2 protein. This causes a buildup of AIR during the AIR to CAIR process, and with the addition
of oxygen, the AIR turns the culture a red color. The culture develops into a pinkish color because
the protein is not binding fully to the response element, and therefore does not transactivate the
ADE2 protein completely. With some ADE2 protein in the AIR to CAIR process, there is less of a
buildup of AIR, but still enough where oxygen interacts with it to create a pinkish color (Aronson
and Silveira, 2009). Therefore, based on our results, p53 T155N partially binds with p53 RE with
consensus and does not bind at all with p53 RE with p21 and BAX. P53 T155N shows different
binding affinities with each of the p53 RE. The mutant binds the most to p53 RE con which has the
highest binding affinity of all the p53

P53 Tumor Protein Analysis
Topic 3: The role of p53 in genome integrity and cancer
A gene that encodes for a protein to function as a tumor suppressor as well as to regulate the cell
cycle are called p53, TP 53 or tumor protein. A mature p53 mRNA is found to be 2.2–2.5 kb in size
and can be found mostly in the spleen and thymus, this gene is separated by 10 introns and are split
into 11 exons. As said in the chapter one of the "p53 suppressor genes" book, the final product of the
p53 genome was first identified as an antigen that bound to a simian virus T antigen and adenovirus
E1B oncoproteins. (Mukhopadhyay, Maxwell & Roth 1995). Mutations, deletion, insertion or
rearrangement of this gene p53 which changes the biochemical and the biophysical properties is
strongly associated with an increase to cancer as the article "p53 in health and disease" describes.
(Vousden & Lane 2007). The mutated genes are called oncogenes, where the DNA is altered from its
original form. These gene help in growth regulation and division of the cells and are often causes the
cells to divide out of control causing cancer to develop from the mutations of the gene p53.
The p53 protein has five highly sustained regions within a cross species amino acid sequence which
are also known as domains. Of these five, there are four functional domains, transcriptional
activation domain at the N–terminus, ... Show more content on Helpwriting.net ...
The inability of the functionality of these genes disrupts apoptosis, programmed cell death and DNA
repair which results in cancer, the regulation and dividing of cells out of

Phosphorylation Is The Formation Of A High Energy Bond...
Phosphorylation is the formation of a high–energy bond between a phosphate group and a target
molecule in the presence of an enzyme. In a cellular environment, it is estimated that 1/10th to half
of the total proteins are phosphorylated to perform a specific function in the cell. The concept of
protein phosphorylation was first introduced by Edmond Fischer and Edwin Krebs in the year 1955,
where they elucidated the necessity of ATP and a kinase (Known then as "converting enzyme").
Interestingly, a reaction which involved protein phosphatases (PP) was reported a decade earlier, but
it was not characterized as PP reaction because of the inability to detect inorganic phosphate as a
product.1
Since the above mentioned early discoveries, it has been well established in eukaryotic cells that
reversible phosphorylation of proteins, executed by kinases and PP, regulate major signal
transduction cascades. The highly specific signaling and reversible nature of phosphorylation seems
to suggest that there would be similar number of protein kinases and PP, but sequencing of human
genome has revealed that about 3% of the genome codes for kinases and PP, out of which
serine/threonine phosphatases (PSP) are 2–5 times fewer than serine/threonine kinases (PSK). This
irregularity in between PSK and PSP can be explained by the combinatorial formation of PSP
holoenzyme formed in between common catalytic and varying regulatory subunits.1
This short review focuses on one of the major PSP, known

Non-Cell Autonomous Tumor Supression by p53
Non–Cell–Autonomous Tumor Suppression by p53
Introduction and significance for the entire manuscript (Guide: approx one quarter page/150 words).
The p53 is a vital tumour suppressor protein in humans which is important for cell cycle regulation.
Ablation of the p53 protein causes the cell to proliferate infinitely that contributes to the
development of tumours. Through the cell–autonomous program the cell–cycle arrest and apoptosis
is caused by the presence of p53. The aim of the journal is to study cellular senescence program in
hepatic stellate cells that is p53–dependent which is formed by dying hepatocytes which secret
factors that influence the tissue microenvironment, preventing fibrosis, cirrhosis and liver cancer via
promoting p53 senescent in these HSCs. The research objectives explain that fibrosis is limited
through the p53–mediated senescence program by stopping HSC proliferation through cell–
autonomous canonical senescence regulators and the non–cell–autonomous effects of SASP on
ECM and immune surveillance. Currently there is a debate on the role p53 plays in HSCs which
influences later stages of liver cancer and the research exhibits that through non–cell–autonomous
mechanisms, p53 can inhibit cancer by manipulating the tissue microenvironment.
Key Figure (Guide: approx one half page/400 words).
Figure 5 is the key figure in this journal. Figure 5 justifies the macrophage function and polarization
how it's influenced by SASP program that is driven by

Pulsing Target Gene Induction
Some signal transduction systems produce multiple pulses of target gene expression in succession
when exposed to a constant level of stimulus (Levine et al., 2013) (Fig. 1.1B). Although pulsing is
similar to transcriptional bursting in that target gene expression levels increase and decrease
repetitively, pulsing is regulated by genetic circuits that activate and deactivate pathway output
regulators with a defined frequency and amplitude instead of relying on stochastic gene expression
(Levine et al., 2013; Raj and van Oudenaarden, 2008). Pulsing can be beneficial during signal
transduction by allowing cells to respond in ways that would be difficult to achieve with a simpler
response (Levine et al., 2013).
The response of p53 to double strand breaks in mammalian cells is a ... Show more content on
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In response to γ–irradiation mediated DNA damage, ATM kinase activates the tumor suppressor
protein, p53, via phosphorylation. Once activated, p53 initiates two negative feedback loops. The
first negative feedback loop is caused by p53 activating the expression of the E3 ubiquitin ligase
Mdm2, allowing Mdm2 to target p53 for degradation. The second negative feedback loop is the
result of p53 activating the expression of the phosphatase Wip1, which dephosphorylates p53 and
therefore reduces its stability. Wip1 also targets ATM kinase, which requires phosphorylation in
order to be in the active state. Therefore, the increased activity of Wip1 silences ATM kinase, which
prevents the activation of p53. If DNA damage persists in the cell, ATM kinase activates p53 once
more after Wip1 expression levels have subsided. Pulsing of p53 activity results in cell–cycle arrest
and DNA repair, and continues until DNA damage has been completely repaired.

Locus Signals Case Study
Introduction
Since its discovery as a product of the alternate reading frame of the mouse Arf/Ink4a locus signals,
the Arf tumor suppressor has been identified as a key sensor of hyperproliferative stimuli such as
those originating from mutant Ras and c–Myc oncoproteins to prevent early stage cancer cells to
undergo neoplastic transformation by inducing senescence or apoptosis (reviewed in Refs. 1, 2).
p19Arf and p16Ink4a are transcribed from separate and unique first exons 1β and 1α (18 kilo base
pairs [kb] apart in mice and 23kb in humans) which splice into two shared exons 2 and 3 (Fig. 1).
These two genes are different tumor suppressor since p19Arf uses only exons 1 and 2 while
p16Ink4a uses all of the exons 1–3 for production of ... Show more content on Helpwriting.net ...
1, 2). Arf sequesters MDM2 in the nucleolus, preventing p53 degradation (Ref. 10). Additionally, it
inhibits transcription factor E2F activity. These actions lead to cell cycle arrest at G1 and G2 (Ref.
8).
Expression of p16INK4a functions to limit cell–cycle progression and to promote cellular
senescence in response to multiple stressors, including oncogene activation, telomere erosion,
reactive oxygen species, and stalled replication forks (reviewed in Refs. 11–14; Fig. 1). Expression
of p16INK4a in healthy cells is low, but once induced, p16INK4a binds and inhibits cyclin–
dependent kinase 4/6 (CDK4/6) activity, thereby promoting a retinoblastoma (RB) – dependent cell–
cycle arrest. This tumor suppressive mechanism is believed to limit the growth of early stage
neoplasms, and accordingly, the p16INK4a–CDK4/6–RB axis is disrupted in most, if not all, human
cancers, with inactivation of p16INK4a being the most common lesion of this pathway (Ref. 11).
Although induction of p16INK4a in response to oncogenic stimuli results in a beneficial, anti–
cancer mechanism, expression of this tumor suppressor also accelerates mammalian cell aging
(Refs. 11–14). Both senescent cells and levels of p16INK4a progressively accumulate with age
(Refs. 15, 16) and

Why Are Elephants Considered For Cancer Research?
Abeggien L, Caulin A, Chan A, Lee K, Robinson R, Campbell M, Kiso W, Schmitt D, Waddell P,
Bhaskara S, Jensen S, Maley C, Schiffman J (2015) Potential Mechanisms for Cancer Resistance in
Elephants and Comparative Cellular Response to DNA Damage in Humans. JAMA. 314(17):1850–
1860.doi:10.1001/jama.2015.13134
Questions
1. Why were elephants considered for cancer research?
2. Why might elephants have evolved to be more resistant to cancers than other mammals?
3. Are there other mammals possessing multiple copies of p53 genes?
4. How is p53 expressed when there are multiple copies?
5. What are the implications of this research for medicine?
The article states that the importance of the research is to gain"insights into human physiology and
pathophysiology, including tumor biology" through research of evolutionary medicine. The
objective of the research as stated by the article is to "identify mechanisms for cancer resistance in
elephants and compare cellular response to DNA damage among elephants, healthy human controls,
and cancer–prone patients with Li–Fraumeni syndrome." Persons with Li–Fraumeni syndrome have
a 90% risk of cancer in their lifetime. Li–Fraumeni syndrome is an inherited autosomal dominant
disorder in which the TP53 gene on one of the homologs of chromosome 17 is mutated usually
passed on from a mutation in germ line cells. TP53 is a tumor suppressor gene which codes for p53,
a nucleophosphoprotein that is able to bind to

P53: The Gene That Cracked The Cancer Code By Sue Armstrong
In the book p53: The Gene That Cracked The Cancer Code by Sue Armstrong, they focus on
statistics rather than a story. This book describes the change throughout time while focusing on the
p53 gene. It talks about different genes that affect p53 and how cancer can happen. This book talks
about science as a process in many different ways. The Scientific process is constantly changing
because science is constantly changing. It not only gives out specific steps in a process but also
explains to the reader what the process is called and how it works. It talks about cell production and
how cells divide. In the quote, on page 21–22, "The forces pushing them to grow and divide come
from within the corrupted cell itself, rather than being signals

The Two Activities of COX-Z and Its Benefits Essay
In Biochemistry, Matthews 4th Edition the COX–2 is a bifunctional endoplasmic reticulum
membrane enzyme with two activities in single heme–containing polypeptide chain. The first, a
cyclooxygenase activity , introduces two molecules of O2 and gives PGG2. The cyclooxygenase
reaction is one of the first steps in eicosanoid synthesis for prostaglandins. The second activity, a
peroxidase, is a two electron reduction of the peroxide to give PGH2. PGH2 is a prostaglandin
endoperoxide that serves as a precursor to other prostaglandins. COX–2 specifically is induced by
cytokines, mitogens, and endotoxins in the inflammatory cells and is responsible for the elevated
production of prostaglandins during inflammation. P53 is a tumor suppressor ... Show more content
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Heptocytes are the cells of the main tissue in the liver. The article describes the relationship between
protein and lipid oxidation with the expression of COX–2 and p53 genes in adult MSCs during their
trans–differentiation into hepatocyte–like cells. The most pivotal data within this article is the
correlation of the p53 down–regulation with the expression of COX–2 during the differentiation of
MSCs into hepatocytes. The changes in the COX–2 and p53 expression in relation to oxidative
stress were studied using a quantitative polymerase chain reaction at mRNA levels over the course
of 21 days with cell samples taken every 7 days. The authors isolated the mononuclear cells in a
culture medium in a CO2 incubator. The non–adherent cells were removed by replacement of the
culture every 3 days so that only the fibroblast–like adherent cells remained which gave the MSCs.
To induce the hepatocyte differentiation of the MSCs they carried out a two–step protocol
employing HGF, DEX, and oncostatin M to promote hepatocyte differentiation.
The first bar chart demonstrates the COX–2 expression at mRNA levels during the hepatocyte
differentiation of MSCs. The second bar chart demonstrates p53 expression at mRNA levels in
MSCs and hepatocytes cells during differentiation. All the assays were carried out in triplicate with
cell samples taken at each time point. The authors

Skin And The Human Body
Skin, the largest organ in the human body covers the whole body. It has many function such as
protecting as barrier against radiations, pathogens etc. Skin mainly consists of 3 layers, epidermis,
dermis and hypodermis. Epidermis is the outer layer of the skin which is comparatively thin and
tough. Epidermis does not have blood vessels and comprised of epithelial cells. Most of the cells in
the epidermis are keratinocytes. Epidermis is originated from the deepest layer of the epidermis
called basal layer. New keratinocytes slowly migrate up toward the surface of the epidermis. Upon
reaching the skin surface, keratinocytes will gradually shed and will be replaced by new cells.
Stratum comeum is the topmost layer of the epidermis. It is ... Show more content on
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Langerhans cells are also part of the epidermis, which is the part of the immune system of the skin.
They help to detect the foreign substances and aid the body against infection and also it will also
take part in development of skin allergies. The epidermis and dermis is separated by basement
membrane.
Basically there are two types of skin cancer: melanoma and non–melanoma skin cancer. Melanoma
skin cancer is developed from the melanocytes which are located at the basal skin layer. Non
melanoma cancer is further classified into two basal cell carcinoma (BCC) and squamous cell
carcinoma (SCC). It is BCC occurs mainly on arms, ears, face and neck where the sun exposure is
more. Basal cell carcinoma looks as slow growing, translucent elevated lesions (Rubin, Chen
(2005)). It is also found that the lesions can be cystic, multicentric, nodular, superficial, pigmented,
and ulcerative.
Risk factors
There are any factors that lead to the onset of epidermal carcinogenesis. Ultraviolet radiations play a
vital role in developing skin cancer. UV radiations can lead to mutations and alter the signaling
pathways. Chances of occurring cancer increases with aging. With respect to this, chances to get
SCC is more than BCC. Smoking, alcohol, radiations also contribute to the development of
epidermal carcinogenesis. Impaired and suppressed immune system also carcinogenesis particularly
SCC. It is found that chances of developing non melanoma cancers like BCC and

Tumor Suppressor Gene P53 Protein Research Paper
Tumor Suppressor Gene p53
Alex Almazan
Animal, Rangeland, and Wildlife Sciences Department, Texas A&M University Kingsville
December 5, 2016 Tumor Suppressor Gene p53
Introduction
The tumor suppressor gene p53 is any variant of a protein that is prearranged by homologous genes
in a variety of organisms. The tumor suppressor gene is essential in multicellular organisms due to
its function of preventing cancer development, therefore giving its identity of being a "tumor
suppressor". In the year 1979, the protein p53 was discovered bound to the T antigen found in the
simian virus (SV40). Because it was found exceptionally in its mutant form, it was first thought of
being an oncogene; it was not until ten years later that the protein was determined to be a crucial
aspect in tumor suppression.
The p53 protein is constantly being synthesized but quickly degrades and therefore results in the
gene being present at low levels. Under standard circumstances, the gene is inactive because it is
bound to the Mdm2 and does not ... Show more content on Helpwriting.net ...
It was then discovered that BRCA2 and p53 do exist physically in vivo in the same complexes.
Further testing was done to analyze probably functional relations between the two genes; the
specific design of the experiment was to determine if the BRCA2 gene inhibits the p53 transcription
activity by acting as a regulator for the gene. Throughout the experiment, there were no recorded
differences in the protein levels expressed in either cells in presence or absence of cotransfaction
containing BRCA2, therefore concluding that BRCA2 was not a general transcription inhibitor, but
did target the p53 transcription

P53 Protein Research Paper
. The TP53 gene is located on the short (p) arm of chromosome 17 at position 13.1. [7]. TP53 has
many important mechanisms of anticancer function and plays a role in apoptosis, genomic stability,
and inhibition of angiogenesis. In its anti–cancer role, p53 works through several mechanisms: p53
can activate DNA, and repair proteins when DNA has sustained damage. Thus, it may be an
important factor in aging. The gene has a very important location in the nucleus of our cells, where
it binds directly to DNA. TP53 can arrest growth by holding the cell cycle at the G1/S regulation
point on DNA damage recognition. If it holds the cell here for long enough, the DNA repair proteins
will have time to fix the damage and the cell will be allowed to

Vascular Endothelial Factor ( Vegf )
Vascular endothelial factor (VEGF) is a potent angiogenic factor which plays an important role in
regulating normal physiological and pathological angiogenesis. Correctly timed expression of VEGF
at appropriate levels is crucial for normal development of vasculature and homeostasis, but also vital
for solid tumour growth. VEGF is highly expressed in solid tumours and is required for the
development and maintenance of blood vessels within the tumour, which is a prerequisite for
successful tumour growth and metastasis.
A co–expression study was undertaken to evaluate the correlated expression of MDM2 and VEGF,
finding that, over eight different cancer cell lines, higher MDM2 expression meant higher VEGF
mRNA, with the cell lines with lost ... Show more content on Helpwriting.net ...
HIF–1 is comprised of two subunits: HIF–1β is constitutively expressed in the cell, however, HIF–
1α is degraded under normoxic conditions. Following a decrease in cellular oxygen levels, HIF–1α
is stabilised and, thus, the heterodimer can form. Overexpression of HIF–1α has been linked to
angiogenesis, tumour invasion and a poor prognosis in many types of cancer [52–55]. The HIF–1
transcription factor binds to the 5' flanking sequence of vegf and is essential for the transactivation
of vegf during hypoxia.
It has been known for some time that hypoxia is a physiological inducer of tumour suppressor p53,
with p53 protein levels increasing under hypoxic conditions. Since MDM2 is the most important
negative regulator of p53, many groups began to look into the precise mechanism of the interaction
between hypoxia and p53, and whether MDM2 was involved.
In 2005, a study showed that MDM2 positively activates HIF–1α in hypoxic tumour cells. Co–
immunoprecipitation showed that MDM2 precipitates with HIF–1α, completely independently of
p53 [56]. Evidence towards the involvement of MDM2 in the regulation HIF–1α expression under
hypoxic conditions came from Lau et al.[57], who found that inhibitory effects on HIF–1α by the
anti–cancer drug 3–(5'–hydroxymethyl–2'–furyl)–1–benzyl indazole (YC–1), was MDM2–
dependent and that overexpression of MDM2 reversed its inhibitory effects.
Another study showed that nutlin–3

Traf4 Case Study
Introduction In the article, "TRAF6 Restricts p53 Mitochondrial Translocation, Apoptosis, and
Tumor Suppression," the experimental study looks specifically at the TRAF6 E3 ligase and its
different effects on the mitochondrial tumor protein 53 (p53). The p53 gene plays a role in
regulation of the cell cycle and cell fate determination. A mutation in the p53 gene is repeatedly seen
in characterized human cancer cells. TRAF6 is shown to inhibit p53 activity by K63–linked
ubiquitination at K24 of p53 in the cytosol. This ubiquitination inhibits the interaction between p53
and MCL–1/BAK; therefore, this restricts p53 from the mitochondria and prevents apoptosis.
Furthermore, this study shows that genotoxic stress affects MCL–1/BAK and p53 ... Show more
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Previous studies have suggested that K63 ubiquitination is associated with anti–apoptotic protein
trafficking pathways. Figure 1 addresses whether K63 ubiquitination is accomplished by the TRAF6
E3 ligase. An immunoblot of p53 was used for U2SO cells in a Ni–NTA assay to determine if K63–
linked ubiquitination of p53 was associated with TRAF6. U2SO cells were used because of their
high proliferation rates. Flag–TRAF6 and p53 were included in the western blot as controls for this
assay. Ubiquitin was tagged with histidine and TRAF6 was tagged with the Flag antibody to assess
protein to protein interactions. This assay shows ubiquitination of p53 in the presence of His–Ub
and Flag–TRAF6 indicating that K63 linked ubiquitination of p53 depends on TRAF6. To determine
if specifically, K63–linked ubiquitination occurs through TRAF6 the authors assessed whether
TRAF6 promotes K48–linked ubiquitination of p53 and proteasomal degradation. An immunoblot
for HA in a Ni–NTA pull–down assay was generated to assess if ubiquitination and proteasomal
degradation occurs at K48 and K63 by TRAF6. HA–p53 and Flag–TRAF6 in U2SO cells were used
to show protein–protein interaction. A

Tumor Protein 53 and its role in Ovarian Cancer Essay
TP53, also called tumor protein 53 is a tumor suppressor gene that encodes p53 and acts as a control
center for the cell to act on when stressed (Brachova). Human p53 is a nuclear phsophoprotein of
molecular weight 53kDa located on chromosome 17 containing 11 exons and 10 introns (Ling). One
of its primary roles is as a transcription factor and in its active state is a homotetramer comprised of
four 393 amino acid residues (Joerger , The tumor suppressor p53). Another main role p53 plays is
as a tumor suppressor and once activated, protects against cancer by "functioning as a sequence–
specific transcription factor, through protein–protein interactions, activating cell cycle arrest,
apoptosis, and DNA damage repair (Brachova)." As one ... Show more content on Helpwriting.net ...
Cancer in the ovaries spreads quickly to other parts of the body and "is the most lethal gynecological
malignancy, with an alarmingly poor prognosis attributed to late detection and chemoresistance
(Brachova)." The ovaries are composed of three different types of tissue: epithelia, germ, and
stromal, with tumors being named for the kinds of cells the tumor started from and whether the
tumor is benign or cancerous. The American Cancer Society's estimates for ovarian cancer in the
United States in 2014 are about 21,980 new cases and about 14,270 deaths. A woman's risk of
getting invasive ovarian cancer in her lifetime is about 1 in 72 and about half of the women
diagnosed with ovarian cancer are 63 years or older (American Cancer Society). Some signs of
ovarian cancer are swelling or bloating of the stomach, having trouble eating, abdominal pain, or
having to urinate frequently (American Cancer Society). Women are more likely to have symptoms
if the disease has spread beyond the ovaries and if they feel any symptoms every day for
consecutive days, they should see a specialist right away. Physical signs indicating ovarian cancer
are finding an enlarged ovary or signs of fluid in the abdomen (American

P53: A Tumor Suppressor Gene
P53 is a tumor suppressor gene. In all kinds of malignant tumors, above 50% appears p53 gene
mutation. The protein encoded by this gene is a transcriptional factor, which controls to start the cell
cycle. Many signals of the cell health directly send to the p53 protein. It also decides when the cells
begin the division. If the cells are damaged and cannot be repaired, the p53 protein would start the
boot process and lead the cell go to apoptosis died. Some p53 deficient cells without this control,
under adverse conditions, cells will continue to split. Just like any other tumor suppressor, p53 gene
normally plays the role of slowing down or monitoring the cell division. The Inhibiting cancer genes
"p53" in cells judges the extent of DNA damage. ... Show more content on Helpwriting.net ...
However Bax (pro–apoptotic gene) interact with mitochondria voltage–dependent ion channel,
release the cytochrome c. p53 can regulate the expression levels of Bax and promote cell apoptosis.
P53 also can induce apoptosis by the receptor protein signal pathway, TNF receptor and the Fas
protein.
After DNA damage, due to the accumulation of mismatch repair, it causes genomic instability.
Besides, the genetic information is changed. P53 can participate in DNA repair process, which itself
has a DNA–binding domain nucleic acid endonuclease activity, resectable mismatch nucleotide,
nucleotide binding and regulate endo repair factor XPB and XPD activity, affect its DNA
recombination and

Cancer And Cancer
The overall analysis of this manuscript was indicating how a particular gene is connected to how
tumors/cancer are suppressed and how tumors/cancer also grow and multiply. When the codon is
manipulated and mutated, the point in which the codon becomes altered, or the point in which the
p53 gene is stimulated, forms reactions that may be harmful or can be non–threatening. The reaction
that could be harmful could generate destruction to the gene and therefore form cancer. A non–
threatening reaction may cause a reconstruction in the mutation, which is beneficial. Two
predominant genes that contribute to cancer are tumor suppressor genes or oncogenes. The gene
known as p53, is also called TP53 or the tumor protein. This gene helps proteins ... Show more
content on Helpwriting.net ...
These genes cause the cell–division process to decelerate, DNA mistakes are corrected, and
apoptosis occurs so mutations are limited and preventing cancer cells from forming. When the tumor
suppressor genes do not function accordingly, this creates issues with cell division and mutations
and then cancer can form. Tumor suppressor genes cause cancer when they are inactive, compared
to the oncogene when they cause cancer because they are activated. An example of a tumor
suppressor gene would be retinoblastoma, an eye cancer, mostly associated with children, that
affects the retina. This disease can be inherited and inherited distortions of tumor suppressor genes
have been discovered in families. These genes can sometimes cause cancer to be inherited, but not
always because normally the mutations are acquired. A specific trans–activator is a part of gene
regulation that raises the rate of a specific gene that can later be activated by a response, or are
unnaturally expressed. These genes are needed for domains of the p53 protein, and also are needed
for protein expression and protein regulation. When a mutation occurs, it happens within the DNA
of the cell. Later, the mutation could be noticed by p53. P53 can become activated and modified
when phosphorylation occurs and this allows the p53 gene to notice the mutation's location within
the DNA of the cell or wherever the damage in the DNA is. After this

Cdp Lab Report
CDDP Induces Phosphorylation of TRAF6 Reducing Ubiquitination in the Cytosol Genotoxic
stresses are hypothesized to reduce K63–linked ubiquitination of p53 which would then cause
TRAF6 to not be recruited. K63–linked ubiquitination of p53 was assessed through stimulation with
the genotoxic stress agent CDDP. To test this hypothesis, an immunoprecipitation assay of mouse
embryonic fibroblasts (MEFs) was used to observe p53 ubiquitination in the cytosol of wild type
and TRAF6 knockout cells in the presence of CDDP for 4 hours. P53 was blotted as an input to
ensure presence. This assay shows that K63–linked ubiquitination of p53 was only observed in wild
type MEFs in the cytosol indicating that TRAF6 is necessary for K63–linked ... Show more content
on Helpwriting.net ...
In an immunoprecipitation assay, 293T cells testing wild type and mutated TQ/SQ sites in TRAF6
was utilized to determine the effect of genotoxic agents on the phosphorylation of TRAF6 at TQ/SQ
motifs. The authors immunoprecipitated for flag asTRAF6 was tagged with the flag antibody. CDDP
and ATM/ATR were used as our tested variables. The assay elucidated that the double mutation of
S13 and T330 on TRAF6 significantly reduced phosphorylation of TRAF6 in the presence of CDDP
and absence of ATM/ATR. Consequently, this data provides information for belief that mutated
TRAF6 is not sufficient for phosphorylation to occur in the presence of CDDP. Finally, a cellular
fractionation assay for 293T wild type and mutant TRAF6 cells with or without CDDP treatment
tested whether such mutation in the presence of genotoxic stress inhibits or promotes TRAF6
expression. As in the previous fractionation studies, tubulin and laminB were loading controls.
These results concluded that the mutant displayed resistance to the CDDP mediated reduction of
TRAF6 in the cytosol. Overall, these studies suggest that CDDP induces phosphorylation of TRAF6
in the cytosol, which may contribute to the reduction of K63–linked ubiquitination in the cytosol.
The information provided thus far suggests that K63–linked ubiquitination of p53 is accomplished
by TRAF6, which is hypothesized to suppress spontaneous apoptosis. Moreover, genotoxic stress is
shown to promote TRAF6

P53 And BRCA1 Genes
Two genes that increase the risk of cancer are the p53 and BRCA1 genes. Mutations within the p53,
BRCA1 genes can lead to cancer due to the fact that if tumor suppressor is mutated it can allow the
genes to grow uncontrollably, creating a malignant tumor making it cancerous. The two types of
tumor cells are benign and malignant tumor cells. A benign tumor is a tumor that stays at its original
site and can removed surgically or killed by radiation. However, a malignant tumor is one that is
able to leave its original site and spread to other parts of the body through the bloodstream
becoming cancerous. The benign tumor is much less harmful than the malignant tumor due to the
fact that it can leave it original site in the body and infect other

Gene And Protein As A Therapeutic Agent For Cancer
In the year 2016, the American Cancer Society projected that 595,690 individuals will pass due to
cancer and 1,685,210 individuals will develop a new cancer case. Many scientists such as Dr. Bert
Vogelstein or Dr. Robert Weinburg have been trying to understand the mechanism behind cancer and
create therapeutic agents that could potentially prevent this disease from occurring. The most novel
and studied gene and protein in regards to cancer is p53. The protein was discovered in the 1970s
when research was focused on cancers that are caused by viruses and was later identified as being a
tumor suppressor (1). One of the most studied areas of cancer is how p53 functions and its role in
the cell cycle which has led to studies that target p53 as a therapeutic agent for cancer (1). In the
year 2001, it was found that the protein product of the gene hSIR2SIRT1, which is a homolog of S.
cerevisiae Sir2 protein, deacetylates the p53 protein and allows for either cell growth arrest or
apoptosis (2). Due to this finding, the Sirtuin 1 protein has been heavily studied and even been
targeted as being a therapeutic target for varying diseases and even involved in the phenomena
known as caloric restriction (3–5). ¬
Current pharmaceutical companies have developed many compounds for cancer treatment that lack
the identification of cellular targets, leading to the absence of cell type specificity in treatment.
However, series of compounds hereafter referred to as de Lijser compounds, have been

Hypoxia-mediated Selection of Cells with Diminished...
Cancer: Necrosis vs. Apoptosis
Cancer is the second leading cause of death in humans. A cancer cell is a cell that has mutated from
its original form and will often grow at a more rapid rate than normal. The body has built certain
mechanisms to protect itself from these types of cells. One of the physiological processes the body
uses to kill off these cells is apoptosis. Apoptosis is sometimes called "cell suicide". When the body
detects that a cell's DNA has mutated and cannot be repaired, the cell will somehow trigger itself to
self destruct. Up until 1972, scientists hadn't really looked carefully at how cells die. Once they did,
it was apparent that two things could happen: necrosis or apoptosis. Necrosis was the term used to ...
Bcl–2 also seems to play a role in this process. Cells that seem to have an over expression of bcl–2
are also resistant to to going through apoptosis. Because the over–expression of bcl–2 inhibits
apoptosis, it is said to be an apoptotic suppressor protein, whereas p53 can be an apoptosis–
promoting gene.
Hypoxia
The article then looks at the role, in solid tumours, of areas of low oxygen (hypoxia) in selecting for
those cells that have mutations in the p53 tumour supressing gene. A common feature inside solid
tumours is hypoxia and an increase of cell death. This happens because often the rate of growth in a
solid tumour outstrips the supply of oxygen to the cells. The normal reaction of a group of cells,
expressing the normal p53 gene, when exposed to an hypoxic region, is an increase in the rate of
apoptosis. However, in a solid tumour there are many cells with many different types of mutations.
In the battle against solid tumours, some tumours resistant to treatment have cropped up. The article
takes a look at the role of hypoxia possibly selecting for those cells resistant to apoptosis.
Rate of Apoptosis
Using the cells of mice the authors selected cells that expressed the normal p53 gene and those that
lacked the expression of p53 (p53 deficient). They then went through a series of tests trying to
determine the effects of low oxygen on the rate of cell death in the different cells. In the

Cancer Pathogenesis Of Cancer
There has been a spontaneous advancement in the understanding the pathogenesis of cancer over the
last two decades. Even though there has been a significant success in the knowledge of tumor, there
still a wide gap in the treatment of tumors. There is a little treatment information available on cancer
making it difficult to control it. Chemotherapy remains the only effective treatment method used.
This study aims at examining the possible roles of the p53 gene in leukemia and how that data can
be utilized for diagnosis and treatment of cancer.
Due to its potent tumor suppressive activity, a molecular understanding of p53 action will create
significant experiences into specific procedures that limit tumor growth and may identify key ...
There are essentially two pathways that transduce signs to start apoptosis in leukemia. The primary
route is the extrinsic pathway. It includes the trimerization of death factors like CD95/Fas/APO–1 or
TNF receptor one which initiates caspase 8, which initiates the apoptotic machinery. The second
pathway is the intrinsic pathway. This pathway involves the p53 gene and is subsequently of more
concern. The p53 gene initiates the arrival of cytochrome C from the mitochondrial intermembrane
space into the cytosol. The cytochrome C in the presence of ATP reasons the oligomerization and
activation of Apaf–1 and caspase 9 as per Schuler, (2000).
Therefore, then prompt caspase three and other effector caspases that cause apoptosis. By utilizing
this data, experiments have been carried out that try to induce apoptosis in cancer cells by activation
of the p53 gene. One particular examination was done on the human osteosarcoma cell line Saos–2,
which is deficient in p53. According to Schuler (2000), an introduction of the p53 gene led to
apoptosis through an intrinsic pathway. Subsequently subjecting p53 to gene treatment might be of
enormous importance in the battle against leukemia.
According to Liu (1994), it has additionally been discovered that p53 mutant tumors are more
unstable genetically and this state of instability may enable the tumors to become more rapidly
resistant to drug treatments.
Since p53

P53 Protein Lab Report
1. A. Prediction: If elephants have multiple copies of functional p53 genes, then elephants will have
a lower rate for developing cancer when compared to organisms with less copies of p53 genes.
2. Could culture cells of both humans and elephants in medium and compare to see which showed
higher levels of expression of the p53 gene.
First the p53 protein would need to be isolated. The simplest method for identifying proteins that
bind to one another tightly is co–immunoprecipitation. In this technique, an antibody is used to
capture and precipitate a specific target protein from an extract prepared by breaking open cells. If
p53 is associated tightly with another protein, the partner protein will precipitate as well. Use
antibodies against p53 ... Show more content on Helpwriting.net ...
We could use induced pluripotent stem cells, where adult cells are taken into an ES–like state by
artificially driving the expression of a set of three transcription regulators called Oct3/4, Sox2, and
Klf4. This converts fibroblasts into cells with practically all the properties of ES cells, including the
ability to proliferate indefinitely and differentiate in varied ways to contribute to any tissue.
Problems are that the conversion is lower and only a small proportion of fibroblasts make the switch
and it may not be safe with such an abnormal developmental history to transfuse these cells back
into

Alteration of p53, p53 Family Proteins and Their Isoforms...
Alteration of p53, p53 family proteins and their isoforms by H pyroli in gastric cancer p53 is the
most studied tumor suppressor protein involved in the negative regulation of cell cycle and
prevention of tumorigenesis . P53 induction usually occurs during cellular stresses like DNA
damage or activation of other oncogenic proteins. P53 transcribes its target genes like p21,PUMA
through p53 response element and halts the cell cycle until the stress is overcome, if not severely
damaged cells are led to apoptosis (A9). Thus it is no wonder that most cancerous cells have either
mutated p53 or completely lost it by deletion or inhibited by other factors. Tp53 gene is located in
the 17p13 region , over a 20kbp region coding a 53 kDa protein. P53 protein comprises of N
terminal transactivation domain, DNA binding domain and C terminal oligomerization domain ().
Mutations in DBDs of p53 are most often found in cancers indicating prime role of DBD in p53
mediated tumor suppression. With advancement in p53 studies previously not conceived pleiotropic
roles of p53 are coming into light. Along with the basic tumor suppressor activity, p53 it is also
active in various cytoplasmic activities related to apoptosis, autophagy, physiological and
pathological processes. P53 has been found to directly promote mitochondrial outer membrane
permeabilisation leading to apoptosis (m1). It is also active in expressing pro–autophagy target
genes (m2). However cytoplasmic wild type as well as

Causes And Treatment Of Pancreatic Cancer
Abstract:
Pancreatic cancer is one of the deadliest cancers with the 4th highest mortality amongst all cancers.
Causes of such high mortality include rapid proliferation, late diagnosis and lack of treatment
options available. New therapy aiming to decrease mortality in pancreatic cancer patients aim to
work with oncolytic viruses to halt the cell cycle pathway. One of the more promising mutations is
the E1A–CR2–deleted AD5 mutants however there are many different types of mutated viruses
aimed at treating pancreatic cancer. Effectiveness of therapy depends on an analysis of cell cultures
and in vivo in terms of type of mutation, effectiveness of mutated gene, viral load, and in vivo
analysis.
Introduction:
Pancreatic cancer is known as one of the most aggressive cancer in the current time period. In the
United States around 40 000 to 50 000 individuals are diagnosed with pancreatic cancer annually. It
is one of the most deadly types of cancer with the 4th highest mortality amongst all cancers.
According to (Han Hsi Wong, 2010)an average 5 year survival rate of about 6%. The life span of
pancreatic cancer is poor as well with an average life span of around 6months. Reasons as to why
this cancer is so deadly is due to the rapid proliferation, late diagnosis and lack of effective
treatment options. Current treatment of pancreatic cancer includes whipple procedure or total
pancreatectomy which cause many problems as the pancreas is removed. Chemotherapeutic agents
include

Regulation and Functions of the p53 Protein
p53 gene, also known as tumor protein 53 (TP53), encodes for a tumor suppressor protein which
regulates the cell cycle and apoptosis. The p53 protein has been described as the guardian of the
genome (1) because of its role in preventing genetic mutation. It belongs to a protein family which
includes p53, p63 and p73 and these are structurally and functionally related to each other. However,
p53 seems to have evolved as a tumor suppressor in higher organisms, while p63 and p73 play a role
in normal developmental biology (2).
Structure of p53
P53 functions primarily as a transcription factor, and is biologically active as a homo–tetramer
comprising of 4 X 393 amino acid residues. Each monomer comprises of several functional
domains:
1. An acidic N–terminus transcription–activating domain 1 and 2 (TAD1/2) – This region interacts
with various transcription factors
2. Proline–rich region (PRR) – This plays a role in p53 stability
3. Central DNA binding domain (DBD) – required for binding to specific sites on the DNA.
4. Tetramerization domain (OD) – required for the assembly of the functional tetramer.
5. Carboxyl terminus domain (CTD) – which is bound to DNA binding domain and is involved in
negative modulation of DNA binding domain.
The central DNA binding domain is the most highly conserved region of p53, when compared to its
other family members, p63 and p73. Loss of tumor suppressor function of p53, as seen in most
cancers, results from missense mutations in the DNA

Advantages And Disadvantages Of Fluorouracil
5–fluorouracil (5–FU) is a pyrimidine antagonist which belongs to the group of antimetabolite
anticancer drugs. It is an analogue of uracil with a fluorine atom at the C–5 position in place of
hydrogen. It enters the cell rapidly using the same facilitated transport mechanism as uracil. They
show pharmacodynamics pathway by incorporation of drug metabolites in DNA or RNA or through
inhibition of proteins involved in nucleotide metabolism. It also acts by inhibiting thymidylate
synthase (TYMS). The fluoropyrimidines are broken down into three active metabolites that contain
pharmacodynamic effects; which are fluorodeoxyuridine monophosphate (FdUMP), fluoro–
deoxyuridine triphosphate (FdUTP) and fluorouridine triphosphate (FUTP) that act through ... Show
more content on Helpwriting.net ...
DPYD is an enzyme our bodies make that helps us process chemotherapy drug for example tymine
and uracil, which make up part of the structure of our gene. Human DPYD gene is located on
chromosome 1p22, encompassing 23 exons and spanning approximately 843kb. The genetic
polymorphism in the DPYD gene will contribute to the decrease level and activation of DPD
enzyme. This condition will lead to reduce in clearance of 5–FU which then contribute to increased
toxicity of 5–fluorouracil in colorectal cancer patients. The adverse drugs events that may happen
related to 5–FU toxicities such as diarrhea, neurotoxicity and

The Major Cytotoxic And Carcinogenic Effects Of...
Microcystins are potent hepatotoxins produced by blue–green algae or cyanobacteria, which are
common in contaminated water. The most common type of microcystins is microcystin–LR (MC–
LR). This report will discuss the major cytotoxic and carcinogenic effects of microcystins, and how
these effects translate into hepatotoxicity. Additionally, cell–based assays will be proposed to
identify and examine the various hepatotoxic characteristics of cyanobacteria or blue–green algae
extracts which contain microcystins.
MC–LR is a cyclic heptapeptide and also a phosphatase inhibitor which specifically targets
serine/threonine phosphatases 1 (PP1) and 2A (PP2A) by directly binding at three sites before
forming covalent adducts.1 These phosphatase inhibitors cause hyperphosphorylation of
cytoskeletal proteins which results in the downregulation of actin and tubulin proteins, and the
upregulation as well as the downregulation of the intermediate filament proteins. Furthermore, a
study on hepatocyte response to microcystin toxin had shown a dramatic increase in 32P
phosphorylation in hepatocytes following exposure to cyanobacteria microcystins.2
Certain proteins of the MAPK superfamily are involved in cytoskeleton development and
maintenance.3 Various mechanisms of cytoskeletal disruption through MC–LR–induced PP1 and
PP2A inhibition (Figure 1) lead to the hyperphosphorylation of proteins downstream of MAPK. For
instance, while the heat shock protein 27 (Hsp27) usually exists as a large

A Study On The P53
The p53 (protein having a molecular weight of 53 (kilodaltons) is a hereditary gene concerned with
Li–Fraumeni Syndrome, a condition that involves development of independent tumor within the
body tissue. The tumor protein accounts on all general human genes. P53 protein is believed to be
among the unifying factor in cancer disease. Its activity alters the formation of tumors by
compressing them. The activities may at times result to uncontrolled cell divisions creating risks for
DNA genes. When the suppression activities are disabled, a person experiencing gene mutation is
prone to cancer disease. P53 mutations within the body tissue enhance the tumor formation by
modifying the molecular networks and increasing the mutagenic effects. Its protein bind stimulates
the formation of p21, which in turn associates with the cell division stimulating protein (cdk2). The
process of cell division is thereby stopped as the p21 composited with the cdk2 cannot facilitate the
next stage of cell division. This creates a path way for the division and formation of tumors as the
p21 proteins are inadequate. Thus, p21 is regarded as a component for terminating tumor formation.
The gene was discovered in human cells and reported to occupy large T–antigen within the affected
tissues cells. In turn, it was protected against viral proteins within the body tissues. Originally, the
p53 gene was considered an Oncogene. This was because the gene was co–related with DNA and
RNA tumor viruses believed to

P53: The Leading Cause Of Lung Cancer
Current Research Being such a complex and important molecule, all of the functions of p53 are not
yet understood. As such, much of the research conducted in the past few decades focuses on
discovering new functions of p53 and the mechanisms behind them. Once discovered, these
functions may be targeted as potential therapeutic approaches to cancer caused by p53 mutations.
Gene Therapy Current cancer treatments such as surgery, chemotherapy, and radiation have been
notoriously inefficient in treating non–small–cell lung cancer (NSCLC), with only an approximately
20% success rate for standard therapies (Roth, Swisher, & Meyn, 1999). As the most common type
of lung cancer and the leading cause of cancer death in the US, it is imperative that novel treatments
be investigated (Chen, 2015). ... Show more content on Helpwriting.net ...
This technique was shown to provide "more effective control of locoregional recurrence in diseases
like NSCLC as well as systemic control of micrometastases," the spread of cancer cells where
secondary tumors are too small to be detected (Roth, Swisher, & Meyn, 1999; "Micrometastases",
n.d.). As explained previously in this paper, p53 is involved in many pathways influencing the cell
cycle and apoptosis, making it a good candidate for targeting using gene therapy. Moreover,
although cancer cells have mutations in many genes that regulate growth and repair, because p53
plays such a significant role in apoptosis, the restoration of its function will induce apoptosis in the
cancer

Of The Mouse Arf Tumor Suppressor?
Since its discovery as a product of the alternate reading frame of the mouse Arf/Ink4a locus signals,
the Arf tumor suppressor has been identified as a key sensor of hyperproliferative stimuli such as
those originating from mutant Ras and c–Myc oncoproteins (Maggi 2014. Basu 2016). p19Arf and
p16Ink4a are transcribed from separate and unique first exons 1β and 1α (18 kilo base pairs [kb]
apart in mice and 23kb in humans) which splice into two shared exons 2 and 3 (Fig. 1). These two
genes are different tumor suppressor since p19Arf uses only exons 1 and 2 while p16Ink4a uses all
of the exons 1–3 for production of the protein (Quelle 1995). This locus has a very unique genomic
structure not found in other mammalian genes due to the ... Show more content on Helpwriting.net
...
Arf sequesters MDM2 in the nucleolus, preventing p53 degradation. Additionally, it inhibits
transcription factor E2F activity. These actions lead to cell cycle arrest at G1 and G2 (Quelle 1997).
Expression of p16INK4a functions to limit cell–cycle progression and to promote cellular
senescence in response to multiple stressors, including oncogene activation, telomere erosion,
reactive oxygen species, and stalled replication forks (reviewed in Sharpless & Sherr 2015; He &
Sharpless 2017; Fig. 1). Expression of p16INK4a in healthy cells is low, but once induced,
p16INK4a binds and inhibits cyclin–dependent kinase 4/6 (CDK4/6) activity, thereby promoting a
retinoblastoma (RB) – dependent cell–cycle arrest. This tumor suppressive mechanism is believed to
limit the growth of early stage neoplasms, and accordingly, the p16INK4a–CDK4/6–RB axis is
disrupted in most, if not all, human cancers, with inactivation of p16INK4a being the most common
lesion of this pathway (Sherr 2016). Although induction of p16INK4a in response to oncogenic
stimuli results in a beneficial, anti–cancer mechanism, expression of this tumor suppressor also
accelerates mammalian cell aging (reviewed in Kim & Sharpless 2006, Sharpless & Sherr 2015, He
& Sharpless 2017). Both senescent cells and levels of p16INK4a progressively

Functions of Ubiquitin Specific Proteases Essay
Eukaryotic cells rely on the ubiquitination of proteins for the proper control of their internal
processes. Adding multiple ubiquitin groups aids in the breakdown of proteins, whereas adding only
one ubiquitin serves regulatory roles other than degradation. The enzymatic activity of two protease
classes frees ubiquitin groups from associated proteins: Ubiquitin specific proteases (USP) and
Ubiquitin C–terminal hydrolases (UCH). USPs are strongly involved in eukaryotic cellular functions
and are found in copious amounts. Certain protein ligases attach ubiquitin to proteins, which
degrades them and interferes with normal cellular functions. The discovery of a specific de–
ubiquitinating enzyme (HAUSP/USP7) found in humans was due to its ... Show more content on
Helpwriting.net ...
The labels associated with the resulting proteins from previous steps were rinsed and removed.
USP7 was purified and utilized in sedimentation trials in varying concentrations. Absorbance
analysis was carried out after the samples were centrifuged. EBNA1 was purified, ubiquitinated, and
combined with USP7, which was purified in previous steps. SDS–PAGE was used to disrupt the
protein interaction and separate them. The separated fragments were then used in a western blot, and
analyzed after probing. The affinity of USP7 for EBNA1 and p53 was tested using a stepwise
combination of titration, incubation, and fluorescence analysis. Lastly, amino acid residues of
EBNA1and USP7 were studied by gel filtration and size–exclusion chromatography. USP7 was
found as hexahistidine fusion after being inserted (through a vector) in insect cells. The de–
ubiquitinating capacity of USP7 for conjugated ubiquitin groups was observed on EBNA1, and was
shown to an efficient process. The capacity of USP7 to de–ubiquitinate specific proteins in various
environments (acidity, presence of inhibitors, and salt concentration) was studied. As seen in figure
2, USP7 sensitivity to salt concentration and acidity showed a steep slope followed by a plateau at
lower salt concentrations and higher pH levels, while lower pH and higher salt concentrations
rendered a steeper, less plateau–like graph. USP7 was found to be a monomer with multiple
domains, each involved

P53 Mutation In Carcinogenesis
Role of P53 mutation in multi–steep process of carcinogenesis: UV radiation lead to have P53
mutation increasing the risk of basal cell carcinoma.
Jamuna Kadariya
Biology 2458–016
TA: Dylan B Parks
October 14,2015
Introduction
As the risk of global warming is increasing every day, people are exposed to the different kinds of
radiations that may have the ability to alter the normal cell functions. Cells functions normally when
they are able to maintain the balance in regulatory environmental conditions. Any disturbance in
such balance will lead the cells to cross the boundary of normal function (Guriji1 et. al, 2001). In
order to maintain the normal cell function, cells use signal transduction pathway to communicate
with each other so that ... Show more content on Helpwriting.net ...
The role of UV–B light in skin carcinogenesis through the analysis of p53 mutations in squamous
cell carcinomas of hairless mice. Carcinogenesis. 18(5): 897–904, 1997.
Madan,V., Lear, T., J., Szeimies, R.M. Non–Melanoma skin cancer. Thelancet. 375: 673–685, 2010.
Web.
Mizuno, T., Tokuoka, S., Kishikawa, M., Nakashima, E., Mabuchi, K., and S.Iwamoto, K.
Molecular basis of basal cell carcinogenesis in the atomic– bomb survivor population: p53 and
PTCH gene alterations. Carcinogenesis. 27(11): 2286–2294, 2006.
Nishigori, C. UV–induced DNA damage in carcinogenesis and its repair. Journal of Dermatological
Science. 23: S41–S44, 2000.
Phillips, J., Moore–Medlin, T., Sonavane, K., Ekshyyan, O., McLarty, J., and O. Nathan, C.A.
Curcumin Inhibits UV Radiation–Induced Skin Cancer in SKH– 1 Mice. American Academy of
Otolaryngology–Head and Neck Surgery Foundation. 148(5): 797–803, 2013.
Weihrauch, M., Bader, M., Lehnert, G., Wittekind, C., Tannapfel, A., and Wrbitzky, R. Carcinogen–
specific mutation pattern in the p53 tumour suppressor gene in UV radiation–induced basal cell
carcinoma. Int Arch Occup Environ Health. 75: 272– 276,

Cilia Function
Cilia are organelles protruding from body cells, consisting of microtubules. These structures are
important for hemostasis and cell development. Along with a group of proteins called kinesins
superfamily proteins (KSFs), the cilia also play an important role in SHH signaling. The proteins
found in this family serve a variety of functions relating to microtubule regulation, such as KIF4A
and KIF21A. KIF4A controls microtubule length during cell division, whereas KIF21A inhibits
microtubule growth at the cell cortex. A prominent member of this family is the protein KIF7, a
homologue of the protein Costal2 (Cos2) found in Drosophila and zebrafish. Both serve relatively
similar functions with relation to the Hh signaling pathway, though there ... Show more content on
Helpwriting.net ...
The level of activity of Gli genes, and thus Hh–pathway activation, determines skin tumor
phenotype: high level signaling is shown to result in BCC and low–level signaling is shown to result
in follicular derived tumors such as basaloid follicular hamartoma (BFH) (2). Gli2 is involved in the
expression of cell cycle regulation genes in the Shh–pathway such as E2F1, CCND1, CDC2 and
epidermal differential genes. Over–expression of Gli2 causes the up–regulation of such cell cycle
regulation genes in developing hair follicles. Shh–activation most specifically promotes degradation
of the p53 tumor suppressor gene (2), thus repressing transcription of p21, a key suppressor of
cyclin E in cell–cycle regulation. Thus, G1 arrest is overrode, and the inability to control cell cycle
is promoted: a key feature of cancer. Sufu and Kif7 have overlapping functions in regulating Gli
transcription factors. Specifically, Gli2 forms a complex with Sufu to prevent transcriptional activity
via preventing accumulation of Gli2 transcriptional factors into the nucleus, thus repressing Hh
pathway transduction (3). Sufu also plays a role in stabilizing Gli2 by blocking Spop, an E3 ligase
involved in degradation of Gli2 (3). In keratinocytes, Kif7

P53 Apoptosis
Among the most important advances in cancer research is the idea of apoptosis and the genes that
control it, where they have a profound effect on the malignant phenotype. P53 was the first tumor
suppressor gene linked to apoptosis. Mutations in this tumor suppressor gene occur in the majority
of human tumors and are often associated with advanced tumor stage and poor patient prognosis.
Studies using p53 knockout mice demonstrated that endogenous p53 could participate in apoptosis.
Also, it is now known that a lot of factors and stimuli can activate p53 to promote apoptosis,
including hypoxia and mitogenic oncogenes.
Bcl2 protein was the oncogene that allowed the discovery of the importance of apoptosis. It did not
behave like a typical oncogene: instead of disrupting normal proliferation controls, Bcl–2 promoted
cell survival by blocking programmed cell death. And it is now clear that mutations in many cancer–
related genes can disrupt apoptosis.
Research studies have provided a lot of understanding of the mechanisms of apoptosis that are
crucial. This may help in the development of drugs that target certain apoptotic genes or pathways.
In all the mechanistic ... Show more content on Helpwriting.net ...
The upstream caspase for the intrinsic pathway is caspase 9 while that of the extrinsic pathway is
caspase 8. The intrinsic and extrinsic pathways converge to caspase 3. Caspase 3 then cleaves the
inhibitor of the caspase–activated deoxyribonuclease, which is responsible for nuclear apoptosis. In
addition to the effect seen on the cytoskeleton, cell cycle and signaling pathways, leading altogether
to morphological changes in apoptosis.
An intense research effort is uncovering the underlying mechanisms of apoptosis and its mutations
in cancer, such as impaired receptor signaling pathway, defects/mutations in p53, reduced
expression of caspases, increased expression of IAPs and disrupted balance of the Bcl–2 family

How Does P53 Prevents Cancer Formation

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