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 5

The metabolic programming directed by DNA methylation to regulate GSIS is conserved in human β cells.

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The metabolic programming directed by DNA methylation to regulate GSIS i...
(A) Static incubation GSIS assay, showing insulin secretion (percentage of insulin content) in differentiated insulin-positive (Ins+) human ES cells (hES-Ins+ cells; left panel), and human islets (h-islets; right panel) at 2.8 mM glucose and 16.7 mM glucose. (B) Relative mRNA expression of indicated genes in sorted GFP+ hES-Ins+ cells, compared with human islets from cadaveric donors (average donor age 43 years; n = 3). CYCLOPHILIN A was used as a housekeeping gene. The error bars represent SEM. *P < 0.05. (C) Bisulfite sequencing analysis for the HK1 and LDHA loci at indicated regions comparing sorted GFP+ hES-Ins+ cells, and EndoC-BH1 human β cell line, compared with human islets from cadaveric donors (representative clones from n = 3 samples per group). Each horizontal line with dots is an independent clone These regions are almost fully DNA methylated (filled circles) in human islets but largely hypomethylated (open circles) in hES-Ins+ cells and the EndoC-BH1 human β cell line. (D) Relative mRNA expression of indicated genes in EndoC-BH1 human β cell line, compared with human islets from cadaveric donors (average donor age 43 years). CYCLOPHILIN A was used as a housekeeping gene. n = 3 independent experiments. The error bars represent SEM. *P < 0.05. (E) Static incubation GSIS assay, showing insulin secretion (percentage of insulin content) in comparing EndoCBH1 cells treated with either a combination of siRNAs targeting HK1 and LDHA, or a scrambled (Scr) siRNA, at 2.8 mM glucose and 16.7 mM glucose. (n = 3). Error bars indicate ± SEM, *P < 0.05, Student’s t test.