Abstract 502: Glucose-6-Phosphate Dehydrogenase Regulates MYH11 and MYOCD Expression in HDAC and miR-1 Dependent Manner

Vascular smooth muscle cell (VSMC) phenotype and function is altered in diabetic and obese patients and animals. Increased activity of glucose-6-phosphate dehydrogenase (G6PD), the rate-limiting enzyme in Pentose Phosphate Pathway, in diabetic and obese animals is associated with decreased expression of MYOCD and MYOCD-dependent genes in the arteries of these animals. Therefore, we hypothesize that reprogrammed metabolism and increased G6PD activity is critical in switching the VSMC from a differentiated to a dedifferentiated phenotype. Our results demonstrated metabolic reprogramming and decrease in MYOCD and MYOCD-driven MYH11 in the aorta of normal chow- and high fat diet (HFD)-fed diabetic Goto-Kakizaki (GK) as compared to control rats. Up regulated G6PD activity in the aorta of these animals positively correlated with increased arterial elastance (R 2 = 0.8322) and total peripheral resistance (R 2 = 0.8364). In vitro , VSMCs (A7r5) treated with Ad-shRNA for G6PD, epiandrosterone (Epi), G6PD inhibitor, and PD2958, a selective inhibitor of G6PD activity, increased (P<0.05) Myocd and Myh11 levels and MYOCD-regulated MYH11 and CNN1 expressions as compared to untreated cells. Furthermore, we found that G6PD-mediated expression of MYOCD and MYH11 expressions was regulated at transcriptional and post transcriptional level. Inhibition of G6PD by PD2958 or Epi decreased histone deacetylase (HDAC) activity by 70-80% (P<0.05), and concomitantly, PD2958 and Ad-shRNA-G6PD up regulated H3K9Ac expression in A7r5 cells as compared to their respective controls. Next, we compared the expression of VSMC-restricted MYH11 in A7r5 cells treated with HDAC inhibitor, Trichostatin (TSA), and PD2958+TSA. Our results demonstrated that MYH11 expression increased by TSA and PD2958 was not further potentiated by PD2958+TSA, suggesting that G6PD inhibition up regulated MYH11 via HDAC inhibition. We also found that G6PD inhibition increased miR-1 levels, which post-transcriptionally regulates MYOCD and MYOCD-dependent gene expression. Therefore, our results collectively suggest that increased G6PD activity is associated with switching of VSMCs from a differentiated to a dedifferentiated phenotype in HDAC and miR-1 dependent manner.

Cyp2c44 gene disruption exacerbated pulmonary hypertension and heart failure in female but not male mice

Epoxyeicosatrienoicacids (EETs), synthesized from arachidonic acid by epoxygenases of the CYP2C and CYP2J gene subfamilies, contribute to hypoxic pulmonary vasoconstriction (HPV) in mice. Despite their roles in HPV, it is controversial whether EETs mediate or ameliorate pulmonary hypertension (PH). A recent study showed that deficiency of Cyp2j did not protect male and female mice from hypoxia-induced PH. Since CYP2C44 is a functionally important epoxygenase, we hypothesized that knockout of the Cyp2c44 gene would protect both sexes of mice from hypoxia-induced PH. We tested this hypothesis in wild-type (WT) and Cyp2c44 knockout (Cyp2c44 (-/-)) mice exposed to normoxia (room air) and hypoxia (10% O2) for 5 weeks. Exposure of WT and Cyp2c44 (-/-) mice to hypoxia resulted in pulmonary vascular remodeling, increased pulmonary artery resistance, and decreased cardiac function in both sexes. However, in female Cyp2c44 (-/-) mice, compared with WT mice, (1) pulmonary artery resistance and right ventricular hypertrophy were greater, (2) cardiac index was lower, (3) left ventricular and arterial stiffness were higher, and (4) plasma aldosterone levels were higher, but (5) there was no difference in levels of EET in lungs and heart. Paradoxically and unexpectedly, we found that Cyp2c44 disruption exacerbated hypoxia-induced PH in female but not male mice. We attribute exacerbated PH in female Cyp2c44 (-/-) mice to elevated aldosterone and as-yet-unknown systemic factors. Therefore, we suggest a role for the human CYP2C genes in protecting women from severe PH and that this could be one of the underlying causes for a better 5-year survival rate in women than in men.