RGD Reference Report - Inhibition of cyclin-dependent kinase 5 activity protects pancreatic beta cells from glucotoxicity. - Rat Genome Database

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Inhibition of cyclin-dependent kinase 5 activity protects pancreatic beta cells from glucotoxicity.

Authors: Ubeda, M  Rukstalis, JM  Habener, JF 
Citation: Ubeda M, etal., J Biol Chem. 2006 Sep 29;281(39):28858-64. Epub 2006 Aug 3.
RGD ID: 2311183
Pubmed: PMID:16887799   (View Abstract at PubMed)
DOI: DOI:10.1074/jbc.M604690200   (Journal Full-text)

Type 2 diabetes (T2D) and Alzheimer disease are degenerative diseases that may share common pathophysiologic mechanisms. Neuronal dysfunction in Alzheimer patients has been linked to overactivity of the cyclin-dependent kinase 5 (CDK5) and its activator p35. Both of these proteins are expressed in the insulin-producing beta cells of the pancreas. Further, glucose enhances p35 gene expression, promoting the formation of active p35/CDK5 complexes that regulate the expression of the insulin gene. In T2D, chronic elevations of glucose, glucotoxicity, impair beta cell function. We therefore postulated that CDK5 and p35 may be responsible for this beta cell impairment and that inhibition of CDK5 might have a beneficial effect. To test this hypothesis, the pancreatic cell line INS-1 was selected as a known in vitro model of glucotoxicity, and roscovitine (10 mum) was used as a CDK5 inhibitor. Chronic exposure of INS-1 cells to high glucose (20-30 mm) reduced both insulin mRNA levels and the activity of an insulin promoter reporter gene. Inhibition of CDK5 prevented this decrease of insulin gene expression. We used DNA binding (gel shift) assays and Western immunoblots to demonstrate that cellular levels of the transcription factor PDX-1, normally decreased by glucotoxicity, were preserved with CDK5 inhibition, as was the binding of PDX-1 to the insulin promoter. Analyses of nuclear and cytoplasmic PDX-1 protein levels revealed that CDK5 inhibition restores nuclear PDX-1, without affecting its cytoplasmic concentration, suggesting that CDK5 regulates the nuclear/cytoplasm partitioning of PDX-1. Using a Myc-tagged PDX-1 construct, we showed that the translocation of PDX-1 from the nucleus to the cytoplasm during glucotoxic conditions was prevented when CDK5 was inhibited. These studies indicate that CDK5 plays a role in the loss of beta cell function under glucotoxic conditions and that CDK5 inhibitors could have therapeutic value for T2D.

Gene Ontology Annotations    Click to see Annotation Detail View

Biological Process
TermQualifierEvidenceWithReferenceNotesSourceOriginal Reference(s)
nucleocytoplasmic transport  IMP 2311183transport of Pdx-1RGD 

Objects Annotated

Genes (Rattus norvegicus)
Cdk5  (cyclin-dependent kinase 5)

Objects referenced in this article
Gene Pdx1 pancreatic and duodenal homeobox 1 Rattus norvegicus

Additional Information