Glucotoxicity is a major mediator of β-cell dysfunction derived from prolonged hyperglycemia. A better understanding of glucotoxicity and preservation of β-cell mass are urgently needed. Carbohydrate response element binding protein (ChREBP) is a glucose-responsive, lipogenic transcription factor with two splice isoforms, ChREBPα and ChREBPβ. We previously showed ChREBPβ is induced by glucose and is required for glucose-stimulated β-cell proliferation in both rodent and human β-cells. In addition, we identified ChREBPβ as a marker for hyperglycemia in β-cells, with its nuclear expression reflecting the progression and severity of the diabetic state. Here, we demonstrate that β-cell death due to glucolipotoxicity (20 mM glucose + 1 mM palmitate) can be prevented by silencing ChREBPβ (6.5±3.1% TUNEL+/Insulin+ in ChREBPβ knock-out islets compared with 47.2±13.6% in control islets, N=7) , most likely via inhibition of lipogenesis and prevention of ceramide-mediated β-cell death. Furthermore, we generated mice with β-cell specific overexpression of ChREBPβ. These mice exhibited increased non-fasting blood glucose levels, impaired glucose tolerance and a marked decrease in β-cell mass, all in a gene dose-dependent manner (OE of one or two alleles of ChREBPβ, N=5) . ChREBPβ overexpression in human beta cells also mimicked glucotoxicity (93.6±3.1% TUNEL+/Insulin+, N=3) . Importantly, we show that ChREBPβ-mediated rodent and human β-cell death was rescued by co-expression with ChREBPα, or by pharmacological activation of Nrf2, a downstream effector of ChREBPα (6.6±1.9 and 2.8±0.9%, respectively, TUNEL+/Insulin+, N=3) . Altogether, our data demonstrate that ChREBPβ is a marker and a causative effector of glucotoxicity, and that downregulating ChREBPβ levels or upregulating ChREBPα levels or its downstream effector (NRF2) rescues β-cells from glucotoxicity. These results position ChREBPβ as a therapeutic target for the prevention of β-cell loss in T2D, an important unmet need in diabetes research.
L.S.Katz: None. G.Brill: None. M.A.Herman: Research Support; Eli Lilly and Company. A.Garcia-ocana: Consultant; Sun Pharmaceutical Industries Ltd. D.Scott: None.
NIH, R01DK130300NIH, R01DK114338NIH, R01DK108905