Epigenetic regulation ataee
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Transcript of Epigenetic regulation ataee
Epigenetic Regulationof Transposable Elements
in Plants
Presented by: Elham Ataee
Shiraz university
1
Contents
1. TRANSPOSON DEFINITION2. TYPES OF TRANSPOSABLE ELEMENTS3. SILENCING MECHANISMS THAT SUPPRESS TEs
Transposon Recognition and Initiation of Silencing Post-transcriptional silencing of TEs by RNAi Chromatin modifications Maintenance and Memory
4 .TRANSPOSON REACTIVATION
5 .TE SPECIFICITIES AND REGULATION
6. TEs CONTRIBUTE TO CHROMOSOME FORM AND FUNCTION
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Transposable elements
DNA sequences that can change their genomic location intragenomically either autonomously or non-autonomously are called transposable elements.
4 Types of transposable elements
5 Types of transposable elements
6 Types of transposable elements
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Transposon Recognition and Initiation of Silencing
Post-transcriptional silencing of TEs by RNAi
Chromatin modifications Maintenance and Memory
Silencing Mechanisms That Suppress TEs
8 Transposon Recognition and Initiation of Silencing
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Potential aberrant transcripts produced by transposons.
Transposon Recognition and Initiation of Silencing
ds RNA
PTGS:Posttranscriptionalgene silencing 21-22 nt
TGS: Transcriptional geneSilencing 24-26 nt
Dicer siRNA
10 Post-transcriptional silencing of TEs by RNAi
AGO
RISC: RNA-induced silencing complexAGO: Argonaute
11Chromatin modifications
Methylation of histone H3 at lysine 9 (H3K9)
DNA methylation on cytosine residues
Proteins that modify chromatin structure
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(PolIVa) RNA polymerase IVa (DCL3) DICER-LIKE 3 (AGO4) ARGONAUTE4(CMT3) CHROMOMETHYASE 3(KYP) KRYPTONITE(RDR2) RNA-DEPENDENT RNA POLYMERASE 2(DRD1) DEFECTIVE IN RNA-DIRECTED DNA METHYLATION 1(DRM2) DOMAINS REARRANGED METHYLTRANSFERASE 2
Maintenance and Memory
24-26 nt
13 Transposon Reactivation
A variety of conditions induce transposon activation.
Tissue culture A source of epigenetic variation
Biotic and abiotic agents Extracts from fungi and bacteria Temperature Stress
Synthetic hybrids Changes in patterns of DNA methylation
TE specificities and regulation14
A heat map showing the distributions of genes and different classes of TEs in a typical grass genome. High concentrations of a particular sequence feature are indicated by red and low concentrations by blue.
Copy number inversely correlates with genic insertion bias
Low-copy-number TEs Insertion into open chromatin
Centromere
LTR retrotransposons
DNA elements
Insert near genes
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Epigenetic status (predominantly DNA methylation) of telomeric and sub-telomeric repeats
Role in regulating telomereelongation in mammalian cells
Centromere, Telomere
TEs, and the epigenetic silencing Role In centromere function
TEs Contribute To Chromosome Form And Function