An Overview of Micro RNA and its application in medical field

2. WHY MICRO RNA IS SO IMPORTANT? (1/2)
Micro RNAs Involve in a wide range of biological
processes
Cell
Cycle
Control
apoptosi
s
hematopoiesis
stem cell
differentiation
neurogenesi
s
cardiac and
skeletal
muscle
development
insulin
secretion
hypoxia
cholesterol
metabolism
viral
replication
Immune
responses
aging
Several Developmental and Physiological Processes
2
During
embryogenesis,
microRNAs play a
key role in the
differentiation and
maintenance of
tissue identity

3. WHY MICRO RNA IS SO IMPORTANT? (2/2)
1. As a diagnostic and prognostic disease biomarkers and predictors of
drug response in diseases such as:
• Cancers
• Heart disease
• Neurological diseases
2. To be used as targets for treatment of different cancers.
 Studies found that miR-506 works to promote apoptosis of cervical cancer
cells.
3

4. WHAT IS MICRO RNA?
• non-coding RNAs that play
key roles in the regulation of
gene expression
• may fine-tune the
expression of as much as
30% of all mammalian
protein-encoding genes at
the post-transcriptional level
• Approximately 22
nucleotides in length
4

5. TYPES OF MICRO RNAS
Broadly speaking, there are two types of miRNAs:
• Cellular
• Extracellular
5
Majority of miRNAs
are detected in
cellular
microenvironment
Cellular MiRNAs
ECmiRNAs can be found in
different biological fluids
Interestingly, the expression pattern of some of miRNAs in
those biological fluids directly reflect the patho-physiological
condition of an organism.

6. HOW DOES IT WORK?
miRNAs function via base-pairing with complementary sequences within
mRNA molecules. As a result, these mRNA molecules are silenced, by
the following processes:
• Cleavage of the mRNA strand into two pieces
• Destablization of the mRNA through shortening of its poly (A) tail
• Less efficient translation of the mRNA into proteins by ribosomes
6
Near-perfect
pairing with their
mRNA targets
A given miRNA may
have hundreds of
different mRNA targets,
and a given target might
be regulated by multiple
miRNAs
Plant Animal
Induces gene
repression
through cleavage
of the target
transcripts
Combinatorial
regulation

7. MICRO RNA BIOGENESIS
7
• Biogenesis of starts in nucleus and ends in cytoplasm.
• Plants use near perfect compatibility whereas animals use partial compatibility

8. CHARACTERISTICS OF EXTRACELLULAR MICRO
RNAS
8
ECmiRNAs are
resistant to high
endogenous
RNase activity
ECmiRNAs in body
fluids remain stable
even they subjected
to harsh conditions
like boiling, high or
low pH, prolonged
storage time and
multiple freeze–thaw
cycles
In contrast to cellular miRNAs and other RNA species

9. POSSIBLE WAYS TO RELEASE EXTRACELLULAR
MICRO RNAS AND THEIR IMPLICATIONS (1/5)
1. Through exosomes
 Exosomes released from human and murine bone marrow-derived mast
cells contain mRNA and miRNA, which are transferrable to other human or
mouse mast cells.
 ECmiRNAs enwrapped with exosomes can alter gene expression in the
recipient cells
 In response to Staphylococcus aureus infection in mammary gland, milk
exosomes are loaded with 14 significantly differentially expressed
ECmiRNAs compared to uninfected group
9

10. POSSIBLE WAYS TO RELEASE EXTRACELLULAR
MICRO RNAS AND THEIR IMPLICATIONS (2/5)
2. Through microvesicles (MV)
 MV can influence several biological pathways and functions for example
cardiovascular disorders.
 miRNAs are found in MV of mesenchymal stem cell, mast cells, cancer cells,
platelets and endothelial cells.
 Embryonic stem cell derived MV are miRNA enriched
 gene expression of neighboring cells might be affected by exosomal
miRNA that was released by embryonic stem cells.
10

11. POSSIBLE WAYS TO RELEASE EXTRACELLULAR
MICRO RNAS AND THEIR IMPLICATIONS (3/5)
3. Through apoptotic bodies (AB)
• AB containing higher number of miR-126 reduces the manifestations of
atherosclerosis in mice, while miR-126-deficient apoptotic bodies have no
such effect
• When miR-126 was found to be highly enriched only in ABs, lower
abundance was reported in MV
 specific release of ECmiRNAs into ABsmay be possible under certain
pathophysiological condition
 Loading of miRNAs into Abs are either specific & selective or whether they
are nonspecifically loaded into Abs in response to a certain stimulus needs
further investigation
11

12. POSSIBLE WAYS TO RELEASE EXTRACELLULAR
MICRO RNAS AND THEIR IMPLICATIONS (4/5)
4. Through High Density Lipoprotein
 Human high density lipoprotein (HDL) and low density lipoprotein (LDL)
derived from blood plasma carry a considerable amount of miRNAs
 Signature of miR-486 and miR-92a associated with HDL is distinct between
vulnerable and stable coronary artery disease patients
 these two ECmiRNAs can be used as biomarker for vulnerable
coronary artery disease.
 Transfer of HDL rich in miR-223 significantly increases the abundance of
endogenous miR-223 concentration and subsequently suppresses the
expression of intracellular adhesion molecule 1 in endothelial cells and
induces an anti-inflammatory action
 The biggest challenge in this field is to prove that these miRNAs are actively
and selectively released from donor cells and spontaneously taken up by
recipient cells to mediate cell to cell communication.
12

13. POSSIBLE WAYS TO RELEASE EXTRACELLULAR
MICRO RNAS AND THEIR IMPLICATIONS (5/5)
5. Through Protein Complex
• ECmiRNAs could be released through binding with Argonaut protein families,
particularly Argonaut 2 (Ago2)
• Only 10% cell-free miRNAs were released in plasma through micro vesicles
whereas potentially 90% of the miRNAs in the circulation cofractionated with
ribonucleo-protein complexes.
• Ago2-protein complexes might be involved with the delivery of miRNA from
donor cell to recipient cells and facilitate cell-cell communications.
• In mammalian organisms, functional mature miRNAs generally bind with one
protein complex called RNA-induced silencing complex (RISC) to regulate
translation of cellular mRNAs.
13

14. IMPORTANT QUESTION IN RESEARCH
Whether a subset of ECmiRNAs is specifically targeted to
transport to another cells via exosomes or microvesicles, gene
expression patterns c could be altered accordingly in the
recipient cells?
Otherwise in this context, ECmiRNAs enwrapped with exosomes
or microvesicles present in bio-fluids would consider only be a
resuiual amount that may not have any biological relevance.
14

15. POTENTIAL ROLES OF EXTRACELLULAR MICRO
RNAS
15
ECmiRNAs
incorporated with
ABs or coupled with
Ago2 could mediate
a warning signal to
the organism about
cellular
dysfunction?
ECmiRNAs can be
transferred from
one cell to another
through exosomes
and in the recipient
cells they can
downregulate their
target genes
Exosomes
enwrapped
ECmiRNAs that can
mediate intercellular
communication
which might have
huge impact

16. The following areas will be discussed:
1.
Inherited
diseases
2.
Cancer
3. Heart
disease
4. Kidney
disease
5.
Nervous
system
6.
Alcoholism
7.
Obesity 8.
Viruses
RELATIONSHIP BETWEEN MICRO RNA
DYSREGULATION AND HUMAN DISEASE (1/12)
16

17. RELATIONSHIP BETWEEN MICRO RNA
DYSREGULATION AND HUMAN DISEASE (2/12)
1. Inherited diseases
17
Mutation in
miR-96 causes
hereditary
progressive
hearing loss Mutation in
miR-184 causes
hereditary
keratoconus
with anterior
polar cataract
Deletion of miR-
17~92 cluster
causes skeletal
and growth
defects

18. RELATIONSHIP BETWEEN MICRO RNA
DYSREGULATION AND HUMAN DISEASE (3/12)
2. Cancer
18
Detection
• Mice engineered to produce a surplus of types of miRNA found in lymphoma cells developed
disease within 50 days and died two weeks later vs. 100 days life span of healthy mice.
• Leukemia can be caused by the insertion of a viral genome next to the 17-92 array of
microRNAs, leading to increased expression of this microRNA
• blood plasma samples collected from patients with early, resectable (Stage II) colorectal
cancer could be distinguished
• specific miRNAs may be associated with certain histological subtypes of colorectal cancer
• Cell-free miRNA are highly stable in blood, are overexpressed in cancer
• Hodgkin lymphoma, plasma miR-21, miR-494, and miR-1973 are promising disease response
biomarkers

19. RELATIONSHIP BETWEEN MICRO RNA
DYSREGULATION AND HUMAN DISEASE (4/12)
2. Cancer (cont’d)
Progression of Cancer
• two types of miRNA inhibit the E2F1 protein, which regulates cell proliferation
• Hepatocellular carcinoma cell proliferation may arise from miR-21 interaction with
MAP2K3, a tumor repressor gene
19

20. RELATIONSHIP BETWEEN MICRO RNA
DYSREGULATION AND HUMAN DISEASE (5/12)
2. Cancer (cont’d)
Prognosis
• low miR-324a levels could serve as an indicator of poor survival.
• Either high miR-185 or low miR-133b levels may correlate with metastasis and poor
survival in colorectal cancer
20

21. RELATIONSHIP BETWEEN MICRO RNA
DYSREGULATION AND HUMAN DISEASE (6/12)
2. Cancer (cont’d)
Treatment
• Circulating miRNAs have the potential to assist clinical decision making and aid
interpretation of positron emission tomography combined with computerized tomography
• miR-205 targeted for inhibiting the metastatic nature of breast cancer.
• miR-506 has been found to work as a tumor antagonist in several studies.
• A 2015 study used a triple helix of three miRNAs embedded in a dextran
aldehyde/dendrimer gel in a mouse model of triple negative breast cancer. mir-205 and
mir-212 targeted specific RNAs, while the other miRNA stabilized the others. The
treatment reduced tumor sizes by 90% with survival times of 75 days
21

22. RELATIONSHIP BETWEEN MICRO RNA
DYSREGULATION AND HUMAN DISEASE (7/12)
3. Heart disease
22
Expression
levels of specific
miRNAs change
in diseased
human hearts 
cardiomyopathie
s
miRNAs have
distinct roles
during heart
development
miRNAs
regulates key
factors important
for
cardiogenesis,
the hypertrophic
growth response
and cardiac
conductance

23. High
throughput
whole transc-
riptome
profiling
of the
FoxD1-
Dicer
revealed
ectopic
upregulation of
pro-apoptotic
gene
RELATIONSHIP BETWEEN MICRO RNA
DYSREGULATION AND HUMAN DISEASE (8/12)
23
Targeted deletion
of Dicer
in the
FoxD1-
derived
renal
progenitor
cells
resulted in a
complex renal
phenotype
MiRNA profiling
defined the
trnscriptional
landscape of
miRNAs for
vascular
devel
-opment
and
Modulate
the renal
phenotype in its
absence.
4. Kidney disease

24. RELATIONSHIP BETWEEN MICRO RNA
DYSREGULATION AND HUMAN DISEASE (9/12)
5. Nervous System
24
Neural miRNAs
are involved
In various stages
of synaptic
development
Some studies find
altered miRNA
expression in
schizophrenia, as well
as bipolar disorder,
major depression and
anxiety disorders

25. RELATIONSHIP BETWEEN MICRO RNA
DYSREGULATION AND HUMAN DISEASE (10/12)
6. Alcoholism
25
Overexpressing
miR-382 resulted in
attenuated drinking
and the inhibition
of DRD1 and delta
fosB upregulation
in rat models
of alcoholism,
demonstrating the
possibility of using
miRNA-targeted
pharmaceuticals in
treatments
Up to 35
different miRNAs
have been found
to be altered in the
alcoholic post-
mortem brain,
all of which target
genes that include
the regulation
of the cell cycle,
apoptosis,
cell adhesion,
nervous system
development and
cell signaling.
miR-206 expression
grew in prefrontal
cortex of alcoholic
rats, targeting it cuts
expression of brain-
derived neurotrophic
factor (BDNF)
critical in
forming/maturing of
new
neurons/synapses &
uses in synapse
growth/plasticity in
alcohol abusers.
Nucleus accumbens
(NA) shows
downregulation
of miR-382
& regulates &
rewards
habits in alcoholics.
Dopamine receptor
D1
(DRD1) targets it,
overexpression 
upregulation of
DRD1 & delta fosB
 transcription in
NA  addiction.

26. RELATIONSHIP BETWEEN MICRO RNA
DYSREGULATION AND HUMAN DISEASE (11/12)
7. Obesity
26
miRNAs elemental in
regulation of adipocyte
differentiation in stem
cells.
Less expression of miR-
155,miR-221,& miR-222, in
adipogenic programming of
immortalized & primary
hMSCs are negative
regulators of differentiation.
Expression of miRNAs
155,221,& 222 inhibits
adipogenesis & repress
induction of master regulators
PPARγ & CCAAT/enhancer-
binding protein alpha
(CEBPA).
This paves
the way for
possible
genetic
obesity
treatments
.
let-7 overexpression
mimicking aging  insulin-
resistant mice  more
prone to diet-induced
obesity & diabetes.
let-7 was inhibition by specific
antagomirs  insulin-sensitive
mice remarkably resistant to
diet-induced obesity &
diabetes.

27. RELATIONSHIP BETWEEN MICRO RNA
DYSREGULATION AND HUMAN DISEASE (12/12)
8. Viruses
27
miRNAs play a key role in host–
virus interactions and pathogenesis
of viral diseases.

28. BIBLIOGRAPHY
28
Wikipedia contributors. "MicroRNA." Wikipedia, The Free Encyclopedia.
Wikipedia, The Free Encyclopedia, 8 Sep. 2017. Web.
24 Aug. 2017
“What are microRNAs?” Exiqon, www.exiqon.com/what-are-microRNAs.
Accessed 24 Aug. 2017.

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