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DOI: 10.1055/s-0038-1641773
Role of free fatty acid signaling in islet function
Publikationsverlauf
Publikationsdatum:
26. April 2018 (online)
Introduction:
Acute exposure of islets to long chain fatty acids amplifies glucose-stimulated insulin secretion (GSIS) in pancreatic beta-cells through activation of the free fatty acid receptor 1 (FFAR1). In accordance, palmitate-induced secretion was largely reduced in islets of Ffar1 -/- mice and of mice carrying the mutation R258W in Ffar1 gene. Glucose tolerance, however, was impaired in Ffar1 -/- mice but improved in R258W mutant mice. In Ffar1 -/- mouse islets, the mRNA level of Ffar3 was reduced. Ffar3 and Ffar2 are short chain fatty acid receptors (SCFA). Their function in beta-cells is still controversial. Here we examined the expression and role of Ffar2 and Ffar3 in beta-cells.
Materials and methods:
The mRNA levels of islets from Ffar1 R258W/R258W, Ffar1 -/- and the respective wild-type littermates were quantified by RT-PCR. RIP-Cre-mT/mG-mice were used to analyze receptor expression in FACS-sorted beta-cells. Glucose-, SCFA- and synthetic FFAR3 agonists (1-MCPC and cpd816)- dependent insulin secretion of isolated mouse islets was assessed in static incubations.
Results:
C57/BL6N and C3HeB/FeJ mouse islets expressed comparable levels of Ffar1, Ffar2, Ffar3 and Gpr119 mRNA. Ffar4 mRNA level was at the detection limit. Ffar1 and Ffar3 mRNAs were enriched 2 – 3-fold in sorted beta-cells compared to non-beta-cells whereas Ffar2 mRNA level did not differ significantly. In sorted beta-cells of Ffar1 -/- mice, the Ffar3 mRNA level was reduced by 80% compared to wild-type beta-cells. Neither SCFA nor FFAR3-agonists affected GSIS.
Conclusion:
These observations suggest that the complete deletion of the Ffar1 gene affected the transcript level of the neighboring Ffar3 in beta-cells of Ffar1 -/- mice.
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