Hypoxic Activation of G6PD Controls the Expression of Genes Involved in the Pathogenesis of Pulmonary Hypertension Through the Regulation of DNA Methylation.

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 were prevented by glucose-6-phosphate dehydrogenase deficiency (G6PD(Def)), and further show that established severe PH in Cyp2c44(-/-) mice was attenuated by knowdown with G6PD shRNA or by G6PD inhibition with an inhibitor (N-ethyl-N'-[(3b,5a)-17-oxoandrostan-3-yl]urea; NEOU). Mechanistically, G6PD(Def), 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) up-regulated expression of the coding genes and long non-coding (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.