149-OR: Genetic Modulation of HNF1A Activity via SGLT2 Deficiency Leads to Transient Intermittent Hyperglycemia: Consequences for HNF1A-MODY

Abstract

Hepatocyte Nuclear Factor-1A (HNF1A) is a master regulator of key glucose-responsive genes in metabolic organs such as the intestine, liver, kidney, and pancreas. Heterozygous mutations in HNF1A cause Maturity-Onset-Diabetes-of-the-Young (HNF1A-MODY) . Mutant carriers are normoglycemic in childhood, but with age, they develop hyperglycemia. Although insulin secretory defects have been extensively studied, it is unclear whether HNF1A deficiency contributes to a progressive decline in alpha cell function. HNF1A-MODY patients display glycosuria and endogenous glucose production linked to reduced renal SGLT2 expression. Since SGLT2 is also expressed in alpha cells and is required for glucagon regulation, we hypothesized that HNF1A coordinates renal and alpha cell SGLT2 activity to maintain glucose homeostasis. Here, we studied Hnf1a regulation of renal Sglt2, Sglt1, and Glut2 in Hnf1a-/- mutant mice, glucagon expression and secretion in siHNF1A transfected human islets and we developed a novel Hnf1a mutant mouse model (Hnf1a+/Δe4-10) . Sglt2 protein was significantly reduced in the kidney of Hnf1a-/- mice, with no changes in Sglt1 or Glut2 protein expression. We observed that HNF1A is heterogeneously expressed in alpha, beta, and delta cells. siHNF1A islets displayed reduced insulin secretion and content, which was rescued by GLP1 treatment. HNF1A deficiency reduced SGLT2 levels, correlating with increased glucagon content and secretion. The Hnf1a+/Δe4-mice were born normoglycemic but became glucose intolerant at 12 weeks of age, mimicking the clinical characteristics of HNF1A-MODY patients. Collectively, these findings indicate that HNF1A deficiency downregulates renal and alpha cell SGLT2 expression, which is associated with an alteration in glucagon secretion in response to glucose stimulation. The new Hnf1a+/Δe4-mouse model may be a useful tool to study the progression of MODY with and without chronic drug treatment. Disclosure A.Acosta-montalvo: None. V.Gmyr: None. M.Cnop: None. J.A.Kerr-conte: None. F.Pattou: None. M.Pontoglio: None. A.Liston: None. C.Bonner: None. C.Saponaro: None. J.Thevenet: None. M.Chiral: None. A.Piron: None. N.Delalleau: None. G.Pasquetti: None. A.Coddeville: None. M.Moreno: None. Funding EFSD/Lilly (2017) awarded to Caroline Bonner, I-SITE ULNE awarded to Caroline Bonner, the European Genomic Institute for Diabetes (ANR-10-LABX-46) , the European Consortium for Islet Transplantation funded by the Juvenile Diabetes Research Foundation. TIGER was developed within the European Union’s Horizon 2020 research and innovation program project T2DSystems, under grant agreement 667191 (to Miriam Cnop) .