Kursus Teknik Biomol UGM

1. EPIGENETICS &
MSP
Kursus Teknik Biologi Molekuler, October
2015
Inna Armandari
Department of Histology and Cell Biology
Faculty of Medicine, Universitas Gadjah Mada

2. Epigenetic phenomena
Identical twins
Calico cat
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3. Epigenetic, Environment, and
Disease
Constant interaction between external and internal environments occur via
epigenetic process. These will lead to normal development and health
maintenance as well as for influencing disease load and resistance.
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Kanherkar e t al., 2014

4. Epigenetics vs Genetics
 Epigenetic was first
coined by Conrad
Waddington in 1942
 Every cell has identical
genome, but the terminal
phenotype is not fixed
 Therefore, epigenetic
serves as a bridge
between genotype and
phenotype
Various unspecified non-genetic mechanisms influencing phenotype
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5. Epigenetic
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• Epigenetic comes from
Greek :Epi ( - o ve r, abo ve ,επί
o utside o f ) – g e ne tics
• Epigenetic is heritable
changes in gene activity and
expression that occur without
alteration in DNA sequence
• Epigenome reflects the overall
epigenetic state of a cell and
refers to global analyses of
epigenetic markers across the
entire genome.

6. Epigenetic modifications
 Epigenetic modifications are crucial for
packaging and interpreting the genome under
the influence
 They can be considered as the punctuation
marks in the genome
 They demarcate the start and end of genes;
provide structure to the chromosome; lead to
genes being expressed (active) or repressed
(silent, inactive)
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7. Epigenetic mechanism
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8. DNA methylation
 The covalent addition of a
methyl group at position 5 of
cytosine  5-methyl C or CMe
 In human & other mammals :
occur at cytosine next to
guanine, linked by phosphate
 CpG site
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2015

9. CpG islands
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Biologi Molekuler
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 Short stretches of CpG-dense DNA  promoter regions 
transcription start site
 In human, 60-80% of 28 million CpG dinucleotides are
methylated
 Cme
in a CpG island denotes inactive promoter owing to the
condensation of chromatin

10. Detecting methylated DNA
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 Specific technique to detect methylation at
CpG island  methylation specific (MS)-PCR
 MSP principle

11. DNA methylation and cancer
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Esteller M Hum. Mol. Genet. 2007;16:R50-R59

12. Histone code
 Histones are the core protein that provide
structural backbone where DNA is packed into
chromatin
 Octamer histone consist of two of each of
histones H2A, H2B, H3, and H4
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13. Histone modifications
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 Post-translational changes on the histone tails, that
are flexible stretches of N or C terminal residues
extending from the globular histone octamer
Type of Modifications :
•Acetylation
•Methylation
•Phosphorylation
•Ubiquitination

14. Histone modifications
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15. Epigenetic state of histone
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Histone acetylation and gene transcription

16. RNAs-based mechanism
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 Type of post-transcriptional gene modification during
which the gene expression is down-regulated or
suppressed by Non-coding RNA (ncRNA)
 Non-coding RNA (ncRNA) : RNA molecule that is not
translated into protein  microRNA (miRNA) and
small interfering RNAs (siRNA)

17. microRNA
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 Small non-coding RNA
molecule (±22 nucleotides)
functions in RNA silencing
and post-transcriptional
regulation of gene
expression
 bind to complementary
sequences on target
messenger RNA transcripts
(mRNAs)  translational
repression and gene
silencing

18. miRNA function
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19. Small interfering (siRNA)
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 a class of double stranded
RNA molecules (±25 bp)
that plays role in RNAi
pathway
 siRNA functions by causing
mRNA to be broken down
after transcription  no
translation

20. Kursus Teknik Biologi Molekuler 2015
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Inna Armandari
Department of Histology and Cell Biology
inna_apt@yahoo.com