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Published byJoel Roberts Modified over 9 years ago
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Control of gene expression Transcriptional Post-transcriptional Epigenetics and long range control
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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
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Control of gene expression Post-transcriptional –Alternative splicing –Alternative polyadenylation –Tissue specific RNA editing –Translational control mechanisms
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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
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Control of gene expression rRNA synthesis –Arrows indicate cleavage sites
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Control of gene expression Initiation of transcription (RNA pol I) Initiation of transcription (RNA pol II)
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Control of gene expression tRNA and 5s RNA promoter elements Initiation of transcription (RNA pol III)
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Control of gene expression Conserved locations of promoter elements in eukaryotes
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Control of gene expression Insulin gene promoter organization –NREnegative regulatory element –CREcAMP response element
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Control of gene expression HS-40 alpha-globin regulatory site –Tissue specific regulation (many sites)
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Control of gene expression Structural domains in transcription factors –HTH –HLH –Zn Finger –Alpha-helix
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Control of gene expression Binding of conserved motifs to double helix
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Control of gene expression Steroid receptors and response elements –GR –ER –PR –RAR –TR –VDR
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Control of gene expression Transcription regulation by glucocorticoids
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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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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
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Control of gene expression Secondary Messengers in Cell Signaling –Cyclic AMP (cAMP) –Cyclic GMP (cGMP) –Phospholipids/Ca
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Control of gene expression The IRE binding protein and iron-response elements (IREs)
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Control of gene expression Genes with multiple promoters –Dystrophin has eight promoters
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Control of gene expression Differential RNA splicing –Wt1 Wilm’s tumor (four splice forms) –Calcitonin gene (tissue specific products)
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Control of gene expression Tissue specific RNA editing –Apolipoprotein B gene (rare)
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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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Control of gene expression Methylation –CpG islands
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Control of gene expression Methylation –Changes in methylation throughout development
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Control of gene expression Methylation –Sex-specific regulation of the Dnmt1 methyl transferase gene –1sosomatic –1spspermatocytes –1oooocytes
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Control of gene expression Transcriptional repression by histone deacetylation –Mediated by methylation –Methylated CpG’s bound by MeCP2 repressor
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Control of gene expression Gene clusters –Coordinated switching –Locus control region –Globin genes
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Control of gene expression Imprinting –DNA methylation key component –Selective expression of genes –Nonequivalence of maternal and paternal genomes
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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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Control of gene expression Programmed rearrangement –Ig and TCR loci in B and T lymphocytes
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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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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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Control of gene expression Inversion or deletion based splicing –Ig kappa light chain V-J splicing
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