Characterize CREB target genes in different tissue types

The CREB family of transcription factors stimulates cellular gene expression following phosphorylation at a conserved serine (Ser133 in CREB1) in response to cAMP and other extracellular signals. In order to characterize CREB target genes in various tissues, we give a cAMP agonist, forskolin (FSK), to cell lines or primary cultures and monitor the gene expression. To eliminate CREB-independent effects of FSK on cellular gene expression, we employed a dominant negative form of CREB called A-CREB, which dimerizes selectively with and blocks the DNA binding activity of CREB but not other bZIP family members. Therefore, genes that are induced by cAMP and the induction was blocked by A-CREB treatment likely represents CREB target genes. Notes: 1) In HEK293T cells, besides the Control+FSK+(FSK-ACREB) experiments, a different set of experiments showing FSK effect on 1hr and 4hr is included. The two sets of data in HEK293T were generated at different times with different batch of cells, and comparison should be limited within each set. The cAMP induced genes at 1hr, however, was similar between the two sets. 2) These is no ACREB data for pancreatic islets or hepatocytes. For hepatocytes, however, we have included fasting liver and refed liver in additional to FSK treated primary hepatocytes. During fasting, glucagon induces cAMP increase in the liver and CREB is activated. Therefore, a more reliable list of CREB target genes in hepatocytes can be obtained by selecting those genes are that induced both during fasting and in FSK treated primary culture. Keywords: parallel sample