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

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Presentation on theme: "Control of gene expression Transcriptional Post-transcriptional Epigenetics and long range control."— 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) Initiation of transcription (RNA pol II)

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

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

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14 Control of gene expression Insulin gene promoter organization –NREnegative regulatory element –CREcAMP response element

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

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

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

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

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24 Control of gene expression Transcription regulation by glucocorticoids

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26 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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29 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

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

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

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33 Control of gene expression Genes with multiple promoters –Dystrophin has eight promoters

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

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

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41 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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43 Control of gene expression Methylation –CpG islands

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45 Control of gene expression Methylation –Changes in methylation throughout development

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47 Control of gene expression Methylation –Sex-specific regulation of the Dnmt1 methyl transferase gene –1sosomatic –1spspermatocytes –1oooocytes

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

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

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

55 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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59 Control of gene expression Programmed rearrangement –Ig and TCR loci in B and T lymphocytes

60 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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62 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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64 Control of gene expression Inversion or deletion based splicing –Ig kappa light chain V-J splicing

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