Hypoxic activation of glucose-6-phosphate dehydrogenase controls the expression of genes involved in the pathogenesis of pulmonary hypertension through the regulation of DNA methylation

Abstract

Metabolic reprogramming is considered important in the pathogenesis of the occlusive vasculopathy observed in pulmonary hypertension (PH). However, the mechanisms that link reprogrammed metabolism to aberrant expression of genes, which modulate functional phenotypes of cells in PH, remain enigmatic. Herein, we demonstrate that, in mice, hypoxia-induced PH was prevented by glucose-6-phosphate dehydrogenase deficiency (G6PDDef), and further show that established severe PH in Cyp2c44−/− mice was attenuated by knockdown with G6PD shRNA or by G6PD inhibition with an inhibitor (N-ethyl-N′-[(3β,5α)-17-oxoandrostan-3-yl]urea, NEOU). Mechanistically, G6PDDef, knockdown and inhibition in lungs: 1) reduced hypoxia-induced changes in cytoplasmic and mitochondrial metabolism, 2) increased expression of Tet methylcytosine dioxygenase 2 ( Tet2) gene, and 3) upregulated expression of the coding genes and long noncoding (lnc) RNA Pint, which inhibits cell growth, by hypomethylating the promoter flanking region downstream of the transcription start site. These results suggest functional TET2 is required for G6PD inhibition to increase gene expression and to reverse hypoxia-induced PH in mice. Furthermore, the inhibitor of G6PD activity (NEOU) decreased metabolic reprogramming, upregulated TET2 and lncPINT, and inhibited growth of control and diseased smooth muscle cells isolated from pulmonary arteries of normal individuals and idiopathic-PAH patients, respectively. Collectively, these findings demonstrate a previously unrecognized function for G6PD as a regulator of DNA methylation. These findings further suggest that G6PD acts as a link between reprogrammed metabolism and aberrant gene regulation and plays a crucial role in regulating the phenotype of cells implicated in the pathogenesis of PH, a debilitating disorder with a high mortality rate.

Inhibition of Glucose-6-Phosphate Dehydrogenase Activity Attenuates Right Ventricle Pressure and Hypertrophy Elicited by VEGFR Inhibitor + Hypoxia

“…We and others have recently proposed that DNA methylation and other epigenetic modifications potentially promote maladaptive gene expression, a determinant of inflammatory and hyperproliferative cell phenotype, in remodeled PA (Hu et al, 2019;Joshi et al, 2020;Potus et al, 2020). Furthermore, we recently showed that expression of Tet2, a DNA demethylase considered as a master regulator of differentiated fate of SMC This article has not been copyedited and formatted.…”

“…Male and female C57BL/6J mice (18-32 g) were purchased from the Jackson Laboratory and randomly divided into four groups: normoxia (Nx), normoxia+Sugen5416 (Nx+SU), hypoxia (Hx), and hypoxia+Sugen5416 (Hx+SU) groups. Mice in Nx group were placed in normoxic (21% O 2 ) environment and in Hx group were placed in a normobaric hypoxic chamber (10% O 2 ) for 6 weeks (Joshi et al, 2020). Mice in Nx+SU and in Hx+SU group received subcutaneous injection of SU5416 (20 mg/kg) once weekly during 3 weeks of Nx (21% O 2 ) or Hx (10% O 2 ) as previously described (Vitali et al, 2014).…”

“…Methylation of DNA is decreased in lungs of Hx and Hx+SU mice: Epigenetic modifications are incriminated in the pathogenesis of PH (Cheng et al, 2019). Recently, we reported that downregulation of ten-eleven translocation 2 (Tet2) DNA demethylase in lungs of Hx Sv129J mice lacking Cyp2c44 gene contributes to the genesis of PH, and also demonstrated that inhibition of G6PD was ineffective in reducing PH in hypoxic Tet2 -/mice (Joshi et al, 2020). Therefore, we assumed that downregulation of Tet2 by Hx may augment DNA methylation in C57BL/6J mice and mediate maladaptive gene expression.…”

“…G6PD and the PPP generate pentose sugar, which is required for the de novo cellular synthesis of RNA and DNA, and NADPH, a key cofactor for reductive and anabolic reactions. Recently, we found that inhibition and knockdown of G6PD in lungs of a chronic hypoxia-induced PH mouse model reduced and reversed: 1) Warburg phenomenon, 2) epigenetic modification (DNA methylation), 3) maladaptive expression of genes that support pulmonary artery remodeling, and 4) PH and left heart dysfunction (Joshi et al, 2020). However, the role of G6PD in the pathogenesis of hypoxia+Sugen5416-induced PH is unknown.…”

DNA methyltransferase 3B deficiency unveils a new pathological mechanism of pulmonary hypertension

“…All these can reflect local DNA methylation signature in the setting of PAH. The other study by Joshi et al ( 17 ) unveiled the mechanisms that link reprogrammed metabolism to aberrant expression of functional phenotype-associated genes in PH. They suggest that functional TET2 is required for G6PD inhibition to reverse PH in mice.…”