Distinct properties of the cAMP-responsive element of the rat insulin I gene
| Autor: | Willhart Knepel, Anke Eggers, B Eckert, Elke Oetjen, T Diedrich |
|---|---|
| Rok vydání: | 1994 |
| Předmět: |
endocrine system
Transcription Genetic medicine.medical_treatment Response element Blotting Western Regulatory Sequences Nucleic Acid CREB Biochemistry Glucagon Membrane Potentials 03 medical and health sciences Islets of Langerhans 0302 clinical medicine medicine Cyclic AMP Animals Insulin Electrophoretic mobility shift assay Cyclic AMP Response Element-Binding Protein Molecular Biology Transcription factor 030304 developmental biology Cell Nucleus 0303 health sciences biology Cell Biology Transfection Molecular biology Rats Blotting Southern Somatostatin Gene Expression Regulation biology.protein Calcium hormones hormone substitutes and hormone antagonists 030217 neurology & neurosurgery Protein Binding Signal Transduction Subcellular Fractions |
| Zdroj: | The Journal of biological chemistry. 269(43) |
| ISSN: | 0021-9258 |
| Popis: | The cAMP response element (CRE)-binding transcription factor CREB can mediate induction of gene transcription in response to calcium as well as to cAMP. Since the rat insulin I gene 5'-flanking region contains a CRE with an octamer-like motif (TGACGTCC), CREB binding and cAMP/calcium responsiveness of the insulin CRE were investigated. In an electrophoretic mobility shift assay and in Southwestern blot experiments, bacterially expressed recombinant CREB bound to the insulin CRE as it did to the rat glucagon and rat somatostatin gene CREs. However, in nuclear extracts of the pancreatic islet cell line HIT, protein complexes binding to the insulin CRE did not contain proteins with CREB-like immunoreactivity, although these bound to the glucagon and somatostatin CREs. When reporter fusion genes were transfected into HIT cells, the isolated insulin CRE increased basal activity and mediated transcriptional activation by cAMP. However, cAMP stimulation of transcription through the insulin CRE was weak when compared with the response through the glucagon and somatostatin CREs. Furthermore, the insulin CRE did not confer responsiveness to membrane depolarization and calcium influx, in contrast to the glucagon and somatostatin CREs. These results demonstrate that the functional properties of the rat insulin I gene CRE are different from those of the rat glucagon and somatostatin CREs which may be explained by a distinct pattern of nuclear protein binding and suggest the existence of post-translational mechanisms that decrease the binding of cellular CREB to the insulin CRE. |
| Databáze: | OpenAIRE |
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