A wealth of recent evidence implicates increasing obesity levels in the rising global epidemic of type 2 diabetes. At a cellular level, high fatty acid concentrations contribute to increasing p-cell dysfunction and eventual p-cell failure. We have shown that the thiazolidinedione (TZD) rosiglitazone has direct effects on pancreatic p-cell function. The aim of this study was to determine the cell signalling molecules mediating these effects, and to test the hypothesis that rosiglitazone can protect pancreatic p-cells from the detrimental effects of free fatty acids. Utilising the mouse p-cell line MIN6, MTT assays showed that at 5 mM glucose concentrations, addition of 0.4 mM palmitate for 72 hours resulted in a 60% loss of MIN6 cell viability (P<O.O 1). However, the presence of 10 p M rosiglitazone completely abolished the effect of palmitate. To determine the cell signalling pathways involved, MIN6 cells were stimulated with 10 u M rosiglitazone for 2 hours and whole cell extracts analysed. Western blot analysis indicated that total levels of the stress activated p38 MAPK were reduced by over 50% (P<0.05) in the presence of rosiglitazone. Rosiglitazone stimulated phosphorylation of ACC (P<O.Ol), an effect inhibited by compound C, indicating that rosiglitazone activates AMPK in MIN6 cells over 2 hours. Finally, casein kinase 2 (CK2) activity assays indicated that rosiglitazone stimulates a 3-fold increase in CK2 activity (P<O.Ol). This activation was inhibited by compound C, indicating that CK2 lies downstream of AMPK in the signalling pathway stimulated by rosiglitazone. In conclusion, this study has shown that rosiglitazone modulates p38, AMPK and CK2 signalling in MIN6 cells, and can protect MIN6 cells from the detrimental effects of palmitate. Our results indicate that early rosiglitazone administration in obese patients at risk of Type 2 diabetes could well protect and preserve p-cell mass and function.
| Identifer | oai:union.ndltd.org:bl.uk/oai:ethos.bl.uk:590004 |
| Date | January 2011 |
| Creators | Landy, Caroline |
| Publisher | University of Brighton |
| Source Sets | Ethos UK |
| Detected Language | English |
| Type | Electronic Thesis or Dissertation |
| Source | https://research.brighton.ac.uk/en/studentTheses/ab4e94da-07ce-46c6-bd1e-aa6d89a4ba02 |
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