Abstract | AIMS/HYPOTHESIS: MATERIALS AND METHODS: Reporter gene assays and biochemical techniques were used. RESULTS: RT-PCR, Western blot analysis and immunohistochemistry demonstrated the expression of DLK in HIT cells and primary mouse islets. In transient transfection experiments, DLK inhibited both GAL4-CREB activity induced by membrane depolarisation, and transcription directed by the CREB binding site, the cyclic AMP response element. Furthermore, DLK inhibited the transcriptional activity conferred by the CREB coactivator, CREB binding protein, both under basal conditions and after membrane depolarisation. DLK was also effective in response to glucose, the most potent physiological stimulus and known to cause membrane depolarisation of beta cells. Inhibition of calcineurin enhanced DLK activity, whereas overexpression of calcineurin reduced the inhibition by DLK of transcription directed by cyclic AMP response element after membrane depolarisation. CONCLUSIONS/INTERPRETATION: These results demonstrate a calcineurin-sensitive inhibition by DLK of CREB activity after membrane depolarisation in pancreatic islet beta cells. This inhibition may, at least partially, be mediated at the coactivator level. The results thus suggest that DLK plays a role in the regulation of beta cell function, including insulin gene transcription and beta cell apoptosis.
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Authors | E Oetjen, A Lechleiter, R Blume, D Nihalani, L Holzman, W Knepel |
Journal | Diabetologia
(Diabetologia)
Vol. 49
Issue 2
Pg. 332-42
(Feb 2006)
ISSN: 0012-186X [Print] Germany |
PMID | 16369771
(Publication Type: Journal Article, Research Support, Non-U.S. Gov't)
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Chemical References |
- Cyclic AMP Response Element-Binding Protein
- Insulin
- CREB-Binding Protein
- MAP Kinase Kinase Kinases
- mitogen-activated protein kinase kinase kinase 12
- Calcineurin
- Glucose
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Topics |
- Animals
- Apoptosis
- Blotting, Western
- CREB-Binding Protein
(antagonists & inhibitors, genetics, physiology)
- Calcineurin
(physiology)
- Cell Line
- Cells, Cultured
- Cyclic AMP Response Element-Binding Protein
(antagonists & inhibitors, genetics, physiology)
- Genes, Reporter
- Glucose
(pharmacology)
- Humans
- Immunohistochemistry
- Insulin
(analysis, genetics)
- Insulin-Secreting Cells
(chemistry, drug effects, physiology)
- Islets of Langerhans
(chemistry, physiology)
- MAP Kinase Kinase Kinases
(genetics, metabolism)
- Membrane Potentials
- Mice
- Reverse Transcriptase Polymerase Chain Reaction
- Transcription, Genetic
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