Adiponectin-Mediated Antilipotoxic Effects in Regenerating Pancreatic Islets

Pathways that stimulate beta-cell regeneration remain of great clinical interest, yet effective therapeutic avenues that promote survival or reconstitution of beta-cell mass remain elusive. Using a mouse model with inducible beta-cell apoptosis followed by adiponectin-mediated regeneration, we aimed to identify key molecules boosting beta-cell viability. In the regenerating pancreatic islets, we examined changes within the transcriptome and observed an extensive up-regulation of genes encoding proteins involved in lipid transport and metabolism. The most prominent targets were further confirmed by quantitative PCR and immunofluorescence. Among the upstream regulators predicted by pathway analysis of the transcriptome, we detected enhanced levels of 2 key transcription factors, Hepatocyte Nuclear Factor 4 alpha and Peroxisome Proliferator-Activated Receptor alpha. Our data suggest that improving pancreatic islet lipid metabolism as an important antilipotoxic phenomenon to boost beta-cell regeneration. This is primarily mediated by the adipokine adiponectin that exerts its action on both the beta-cell directly as well as on the adipocyte. Adiponectin induces lipid metabolism gene expression in regenerating islets through Hepatocyte Nuclear Factor 4 alpha and Peroxisome Proliferator-Activated Receptor alpha. Adiponectin also modulates leptin levels via preserving adipose tissue mass in the insulinopenic state.