DNA methylation directs functional maturation of pancreatic β cells
Sangeeta Dhawan, … , Aleksey Matveyenko, Anil Bhushan
Sangeeta Dhawan, … , Aleksey Matveyenko, Anil Bhushan
Published June 22, 2015
Citation Information: J Clin Invest. 2015;125(7):2851-2860. https://doi.org/10.1172/JCI79956.
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Research Article Development Endocrinology Genetics Metabolism

DNA methylation directs functional maturation of pancreatic β cells

Abstract

Pancreatic β cells secrete insulin in response to postprandial increases in glucose levels to prevent hyperglycemia and inhibit insulin secretion under fasting conditions to protect against hypoglycemia. β cells lack this functional capability at birth and acquire glucose-stimulated insulin secretion (GSIS) during neonatal life. Here, we have shown that during postnatal life, the de novo DNA methyltransferase DNMT3A initiates a metabolic program by repressing key genes, thereby enabling the coupling of insulin secretion to glucose levels. In a murine model, β cell–specific deletion of Dnmt3a prevented the metabolic switch, resulting in loss of GSIS. DNMT3A bound to the promoters of the genes encoding hexokinase 1 (HK1) and lactate dehydrogenase A (LDHA) — both of which regulate the metabolic switch — and knockdown of these two key DNMT3A targets restored the GSIS response in islets from animals with β cell–specific Dnmt3a deletion. Furthermore, DNA methylation–mediated repression of glucose-secretion decoupling genes to modulate GSIS was conserved in human β cells. Together, our results reveal a role for DNA methylation to direct the acquisition of pancreatic β cell function.

Authors

Sangeeta Dhawan, Shuen-Ing Tschen, Chun Zeng, Tingxia Guo, Matthias Hebrok, Aleksey Matveyenko, Anil Bhushan

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Figure 4

β Cells lacking Dnmt3a are functionally immature.

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β Cells lacking Dnmt3a are functionally immature. (A) Plasma insulin lev...
(A) Plasma insulin levels in 6-week-old 3aRCY-KO mice and littermate-control 3aRCY-Het mice (fasted 6 hours) at 0 and 30 minutes after i.p. injection of 2 g/kg glucose (n = 3 for each genotype). (B) Insulin secretion (percentage of insulin content) in a dynamic islet perifusion assay comparing islets from 6-week-old 3aRCY-KO or control 3aRCY-Het littermates at 4 mM and 16 mM glucose. (C) Average insulin secretion (percentage of content) in the dynamic islet perifusion GSIS at 4 mM and 16 mM glucose, comparing 3aRCY-KO islets with control 3aRCY-Het islets from n = 3 mice aged 6 weeks. (D) Static incubation GSIS assay, comparing insulin secretion (percentage of insulin content) in islets from 3aRCY-KO mice with control 3aRCY-Het islets (n = 3 mice), at 2.8 mM glucose, 16.7 mM glucose, and 20 mM arginine. (E) Static incubation GSIS assay, comparing insulin secretion (percentage of insulin content) in islets from 6-week-old 3aRCY-KO mice with control 3aRCY-Het islets, at 2.8 mM glucose, 16.7 mM glucose, 100 μM diazoxide, and a 100 mM each of diazoxide and tolbutamide (n = 3 mice). (F) Static incubation GSIS assay, comparing insulin secretion (percentage of insulin content) in islets from 6-week-old 3aRCY-KO mice, treated either with a combination of siRNAs targeting Ldha and Hk1, or scrambled (Scr) siRNA, at 2.8 mM glucose and 16.7 mM glucose (n = 3 mice, islets from each mice divided into the 2 experimental groups). Error bars indicate ± SEM; *P < 0.05, **P < 0.01, ***P < 0.005, Student’s t test.