Genetic background influences MAFAS64F-mediated diabetes penetrance in male mice

Pancreatic beta-cells require the coordinated expression of transcription factors such as MAFA to dynamically secrete insulin to maintain euglycemia. A naturally occurring mutation in MAFA (MAFAS64F) produces a long-lived variant protein which predisposes carriers to dichotomous conditions of either maturity (adult)-onset diabetes of the young (MODY) or hypoglycemia in a sex-dependent manner. Here we show that genetic background modulates disease penetrance in MafAS64F/+ male mice. Specifically, MafAS64F/+ males backcrossed to a C57/Bl6J (C57) background prevented dysglycemia, while C57 MafAS64F/+ males bred one generation to an SJL/J background (mixed) manifested overt diabetes, impaired insulin secretion, and accelerated beta-cell senescence. MafA protein levels, phosphorylation status, and target gene expression in C57 MafAS64F/+ male islets were more comparable to wildtype males. RNA sequencing of C57 MafAS64F/+ male islets revealed fewer differentially expressed genes than mixed background male islets, including transcriptional signatures of beta-cell senescence. In addition, retinoic acid signaling, another signature of cellular aging, was uniquely downregulated in C57 MafAS64F/+ male islets. Indeed, core retinoic acid signaling receptor RARalpha; and known target genes were downregulated in C57 MafAS64F/+ male islets. CUT&RUN mapping revealed that MafA directly impacted retinoic acid receptor alpha Rara expression. In sum, these data show that genetic factors can impact unique pathways to modulate disease penetrance in mice modeling MAFA-MODY.