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The Transcriptional Response Dr Debbie Cunningham d.cunningham@bham.ac.uk Progress through the cell cycle involves the induction of gene expression There is an ordering of genes switched on in response to growth factor stimulation Immediate early - within minutes Delayed early - within hours Late - around onset of S phase Induction and repression of genes is transient DNA Array Experiment 3T3 Fibroblasts are stimulated with serum RNA is taken at different time points Hybridised to Array of cDNAs Immediate Early Genes 229 genes out of 14,000 analysed Highly enriched for genes involved in transcriptional regulation Induction of immediate early gene expression does NOT require protein synthesis J. Biol. Chem. 2007, 282:23981-23995 Cycloheximide does not inhibit gene expression Induction of delayed early gene and late gene expression DOES require protein synthesis J. Biol. Chem. 2007, 282:23981-23995 Cycloheximide does inhibit gene expression Late genes are switched on after the restriction point has passed Receptor activation Immediate Delayed early Late early Time In the absence of growth factor signalling gene transcription is latent Growth factor stimulation leads to expression o