Prolyl Hydroxylase Domain Protein 2 Plays a Critical Role in Diet-Induced Obesity and Glucose Intolerance

Abstract

Matsuura et al Role of PHD2 in Adipocytes 2079Several cell culture studies have revealed that hypoxia and HIF convert cell metabolism that is dependent on aerobic glucose oxidation and fatty acid synthesis into that which is dependent on anaerobic glycolysis. HIF not only upregulates a series of glycolytic enzymes 15,16 but also actively inhibits oxidative phosphorylation in mitochondria by inducing pyruvate dehydrogenase kinase 1 (PDK1).17,18 PDK1 inhibits pyruvate dehydrogenase activity and consequently reduces the conversion of pyruvate to acetyl CoA, an essential substrate for oxidative phosphorylation. 17,18 In addition, HIF inhibits adipogenesis by inducing DEC1/Stra13. 13 These HIF-induced metabolic alterations such as increased glucose consumption and less fatty acid synthesis might be beneficial for nutrient excess in obese or diabetic subjects. Although HIF could be a potential therapeutic target, direct manipulation of HIF is often difficult in vivo. In contrast, PHD is an ideal target to manipulate HIF levels, and several chemical inhibitors of PHD have been developed. 19 However, the role of adipocyte PHD in the development of obesity-induced glucose intolerance has not been determined. In the present study, we generated mice lacking PHD2, also known as Egl 9 homolog1 (EglN1) in adipocytes, because PHD2 is the most crucial isoform to regulate HIF level in vitro 20 and in vivo 21 among 3 PHD isoforms (PHD1, PHD2, and PHD3). We found that PHD2 deletion in adipocyte attenuates weight gain and alleviates glucose intolerance induced by a high-fat diet (HFD). MethodsAdditional details of the experimental procedures are included in the online-only Data Supplement.All animal procedures were approved by the Animal Care and Use Committee of Kyushu University and conducted in accordance with the institutional guidelines. Previously generated Phd2-floxed mice f/f mice. Phd2 f/f mice served as controls. These mice were fed an HFD containing 60% kcal fat (High Fat Diet 32, Clea Japan, Inc) from 12 to 18 weeks of age. Mice 12 and 18 weeks of age were analyzed. Preparation of cell lysate and total RNA, Western blot analysis, quantitative reverse transcription-polymerase chain reaction, luciferase assay, and histological/immunohistochemical analysis were performed using conventional methods. The primer sequences for quantitative reverse transcription-polymerase chain reaction are shown in Table I Figure 1A and Figure IA in the online-only Data Supplement). Expression of PHD2 in heart and bone marrowderived macrophages was slightly reduced. We did not find any apparent abnormalities in the appearance in Phd2 Figure 2B and 2D). However, the extent of HFD-induced adipocyte hypertrophy was significantly reduced in Phd2 f/f /aP2-Cre mice compared with control mice (Figure 2C and 2D). A detailed analysis of the size distribution of the adipocytes revealed that WAT from controls contained a greater number of larger adipocytes (>10 000 μm 2 ) than that Enhanced Angiogenesis in WAT From HFD-Fed Phd2f/f /aP2-Cre Mice B...

Hypoxia-Inducible Factor Prolyl 4-Hydroxylase-2 Inhibition Protects Against Development of Atherosclerosis

“…20 HIF-P4H-2 inhibition leads to improved lipid and glucose metabolism, reduced serum cholesterol levels, and protection from obesity and metabolic dysfunction. 9,21,22 We present evidence here that pharmacological and genetic HIF-P4H-2 inhibition also protects from atherosclerosis development.…”

HIF Prolyl 4-Hydroxylase-2 Inhibition Improves Glucose and Lipid Metabolism and Protects Against Obesity and Metabolic Dysfunction

“…Currently, no explanation is available for the discrepancy between those data and the beneficial effects of Hif-a stabilization by Hif-p4h-2 deficiency, but the additional stabilization of Hif-2a has been suggested to possibly play an important role (25).…”

“…Mice with adipocyte-specific Hif-p4h-2 deletion also have less WAT, smaller adipocytes, a lower number of adipose tissue macrophages, and improved glucose tolerance (25); however, such changes were seen only in those fed an HFD, and no changes were reported in serum cholesterol levels, suggesting that Hif-p4h-2 deficiencies in several tissues play an important role in metabolic changes in Hif-p4h-2 gt/gt mice. Acute hepatic Hif-p4h-3 deletion has also been reported to improve glucose tolerance and insulin sensitivity, but no data were available on its effects on weight gain or serum cholesterol levels (26).…”

PHD2: from hypoxia regulation to disease progression

“…Interestingly, studies on the role of PHD2 in this condition have suggested a detrimental role of this protein during obesity. While Matsuura et al131 observed that deletion of PHD2 in adipocytes attenuated weight gain and alleviated the glucose intolerance that occurs during a high-fat diet model, with reduced fat mass and lower macrophage infiltration into the white adipose tissue, Michailidou et al132 showed an increased adipose mass in adipose-specific PHD2-knockout mice. Notwithstanding the disparity in adipose mass, this group also observed a normal glucose tolerance in these mice, with reduced levels of circulating fatty acids and no increase in macrophage levels in the white adipose tissue 132.…”