Elevated hepatic expression of H19 long noncoding RNA contributes to diabetic hyperglycemia

Abstract

Excessive hepatic glucose production (HGP) contributes significantly to the hyperglycemia of type 2 diabetes; however, the molecular mechanism underlying this dysregulation remains poorly understood. Here, we show that fasting temporally increases the expression of H19 long noncoding RNA (lncRNA) in nondiabetic mouse liver, whereas its level is chronically elevated in diet-induced diabetic mice, consistent with the previously reported chronic hepatic H19 increase in diabetic patients. Importantly, liver-specific H19 overexpression promotes HGP, hyperglycemia, and insulin resistance, while H19 depletion enhances insulin-dependent suppression of HGP. Using genome-wide methylation and transcriptome analyses, we demonstrate that H19 knockdown in hepatic cells alters promoter methylation and expression of Hnf4a, a master gluconeogenic transcription factor, and that this regulation is recapitulated in vivo. Our findings offer a mechanistic explanation of lncRNA H19's role in the pathogenesis of diabetic hyperglycemia and suggest that targeting hepatic H19 may hold the potential of new treatment for this disease.

Hepatic TET3 contributes to type-2 diabetes by inducing the HNF4α fetal isoform

“…Fasting upregulates hepatic TET3. We have previously documented that fasting upregulates hepatic expression of H19 long noncoding RNA contributing to increased expression of HNF4α 17 . Overnight fasting expectedly increased levels of H19 as well as mRNAs for PGC-1α, HNF4α, PEPCK, and G6PC; curiously, fasting also increased mRNA expression of TET3, but not of its family members TET2 and TET1 ( Supplementary Fig.…”

“…2a). To determine how TET3 is upregulated, primary hepatocytes from wild-type (WT) and H19 KO mice 17,18 were stimulated with glucagon. In WT hepatocytes, H19 expression was readily induced by glucagon, as was TET3; however, in KO hepatocytes, glucagon no longer stimulated TET3 expression ( Supplementary Fig.…”

“…2b). Next, H19 was expressed in WT primary hepatocytes with an adeno-associated virus-based vector (AAV-H19 17 ) in absence of glucagon. Exogenous H19 expression increased TET3 mRNA levels ( Supplementary Fig.…”

“…3a), confirming the specificity of the TET3 siRNA. As stated in our "Methods" section, all primary hepatocyte experiments (e.g., glucagon stimulation and TET3 overexpression) were performed on cells maintained in a complete culture medium (CM) containing serum, insulin, and dexamethasone, conditions optimized and important for cell viability 17 . These conditions allowed cell viability to persist to the end of the experiments ( Supplementary Fig.…”

Non-Coding RNAs in IGF-1R Signaling Regulation: The Underlying Pathophysiological Link between Diabetes and Cancer

“…Depletion of H19 would result in bioavailability of let-7, triggering IR removal, thereby impairing the oxygen signal and reducing sugar intake [113]. However, in another study of a DM mouse model, hepatic H19 was upregulated and contributed to hyperglycemia [114]. Since let-7a is also a regulator of IGF-1R, H19 depletion will ideally lead to a decrease in IGF-1R.…”