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Control of gene expression

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Presentation on theme: "Control of gene expression"— Presentation transcript:

1 Control of gene expression
Transcriptional Post-transcriptional Epigenetics and long range control

2 Control of gene expression
Transcriptional Tissue specific transcription factors Binding of hormones, growth factors etc. to response elements Use of alternative promoters in a single gene

3 Control of gene expression
Post-transcriptional Alternative splicing Alternative polyadenylation Tissue specific RNA editing Translational control mechanisms

4 Control of gene expression
Epigenetics and chromatin structure Allelic exclusion (rearrangements, imprinting, X inactivation) Long range control by chromatin structure (position effects Pax6 in aniridia) Cell position-dependent, short range signaling

5 Control of gene expression
rRNA synthesis Arrows indicate cleavage sites

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7 Control of gene expression
Initiation of transcription (RNA pol I)

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9 Control of gene expression
tRNA and 5s RNA promoter elements Initiation of transcription (RNA pol III)

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11 Control of gene expression
Conserved locations of promoter elements in eukaryotes

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13 Control of gene expression
Insulin gene promoter organization NRE negative regulatory element CRE cAMP response element

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15 Control of gene expression
HS-40 alpha-globin regulatory site Tissue specific regulation (many sites)

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17 Control of gene expression
Structural domains in transcription factors HTH HLH Zn Finger Alpha-helix

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19 Control of gene expression
Binding of conserved motifs to double helix

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21 Control of gene expression
Steroid receptors and response elements GR ER PR RAR TR VDR

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23 Control of gene expression
Transcription regulation by glucocorticoids

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25 Control of gene expression
Target gene expression via signal transduction Protein kinase: hormonal signaling through cAMP-pt kinase A pathway Cytoplasmic transcription factor NF kappa B and translocation to the nucleus

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27 Control of gene expression
Major Classes of Cell Surface Receptor G protein coupled Serine-Threonine kinase Tyrosine kinase Tyrosine kinase associated JAK (janus protein kinase) activity in JAK-STAT signaling Ion channel-linked

28 Control of gene expression
Secondary Messengers in Cell Signaling Cyclic AMP (cAMP) Cyclic GMP (cGMP) Phospholipids/Ca

29 Control of gene expression
The IRE binding protein and iron-response elements (IREs)

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31 Control of gene expression
Genes with multiple promoters Dystrophin has eight promoters

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33 Control of gene expression
Differential RNA splicing Wt1 Wilm’s tumor (four splice forms) Calcitonin gene (tissue specific products)

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36 Control of gene expression
Tissue specific RNA editing Apolipoprotein B gene (rare)

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38 Control of gene expression
Methylation and gene expression Largely confined to CpG dinucleotides CpG islands Methylation patterns change during development Sex-specific regulation

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40 Control of gene expression
Methylation CpG islands

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42 Control of gene expression
Methylation Changes in methylation throughout development

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44 Control of gene expression
Methylation Sex-specific regulation of the Dnmt1 methyl transferase gene 1so somatic 1sp spermatocytes 1oo oocytes

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46 Control of gene expression
Transcriptional repression by histone deacetylation Mediated by methylation Methylated CpG’s bound by MeCP2 repressor

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48 Control of gene expression
Gene clusters Coordinated switching Locus control region Globin genes

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51 Control of gene expression
Imprinting DNA methylation key component Selective expression of genes Nonequivalence of maternal and paternal genomes

52 Control of gene expression
Monoallelic expression from biallelic genes Allelic exclusion according to parent of origin Genomic imprinting Allelic exclusion independent of parent of origin X-chromosome inactivation Programmed DNA rearrangement Unknown mechanism

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55 Control of gene expression
Programmed rearrangement Ig and TCR loci in B and T lymphocytes

56 Control of gene expression
Programmed rearrangement Ig heavy chain locus on 14q32 86 variable (V) sequences 30 diversity (D) sequences 9 joining (J) segments 11 constant (C) sequences

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58 Control of gene expression
Programmed rearrangement Light chain synthesis Somatic recombination V to J RNA splicing VJ to C Heavy chain synthesis Two sequential somatic recombination events yield DJ and VDJ RNA splicing VDJ to C Somatic recombination VDJ to different C (switching)

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60 Control of gene expression
Inversion or deletion based splicing Ig kappa light chain V-J splicing

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