Objective

Recent evidence indicates that inhibition of prolyl hydroxylase domain (PHD) proteins can exert beneficial effects to improve metabolic abnormalities in mice and humans. However, the underlying mechanisms are not clearly understood. This study was designed to address this question.

Methods

A pan-PHD inhibitor compound was injected into WT and liver-specific hypoxia-inducible factor (HIF)-2α KO mice, after onset of obesity and glucose intolerance, and changes in glucose and glucagon tolerance were measured. Tissue-specific changes in basal glucose flux and insulin sensitivity were also measured by hyperinsulinemic euglycemic clamp studies. Molecular and cellular mechanisms were assessed in normal and type 2 diabetic human hepatocytes, as well as in mouse hepatocytes.

Results

Administration of a PHD inhibitor compound (PHDi) after the onset of obesity and insulin resistance improved glycemic control by increasing insulin and decreasing glucagon sensitivity in mice, independent of body weight change. Hyperinsulinemic euglycemic clamp studies revealed that these effects of PHDi treatment were mainly due to decreased basal hepatic glucose output and increased liver insulin sensitivity. Hepatocyte-specific deletion of HIF-2α markedly attenuated these effects of PHDi treatment, showing PHDi effects are HIF-2α dependent. At the molecular level, HIF-2α induced increased Irs2 and cyclic AMP-specific phosphodiesterase gene expression, leading to increased and decreased insulin and glucagon signaling, respectively. These effects of PHDi treatment were conserved in human and mouse hepatocytes.

Conclusions

Our results elucidate unknown mechanisms for how PHD inhibition improves glycemic control through HIF-2α-dependent regulation of hepatic insulin and glucagon sensitivity.

中文翻译：

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脯氨酰羟化酶的抑制通过 HIF-2α 依赖性机制增加肝脏胰岛素并降低胰高血糖素敏感性。

客观的

最近的证据表明，脯氨酰羟化酶结构域 (PHD) 蛋白的抑制可以发挥有益作用，以改善小鼠和人类的代谢异常。然而，潜在的机制尚不清楚。本研究旨在解决这个问题。

方法

在肥胖和葡萄糖耐受不良发作后，将泛 PHD 抑制剂化合物注射到 WT 和肝脏特异性缺氧诱导因子 (HIF) -2α KO 小鼠中，并测量葡萄糖和胰高血糖素耐受性的变化。基础葡萄糖通量和胰岛素敏感性的组织特异性变化也通过高胰岛素正常血糖钳夹研究来测量。在正常和 2 型糖尿病人肝细胞以及小鼠肝细胞中评估了分子和细胞机制。

结果

在肥胖和胰岛素抵抗发作后施用 PHD 抑制剂化合物 (PHDi) 通过增加小鼠的胰岛素和降低胰高血糖素敏感性来改善血糖控制，而与体重变化无关。高胰岛素正常血糖钳夹研究表明，PHDi 治疗的这些影响主要是由于基础肝葡萄糖输出降低和肝脏胰岛素敏感性增加。HIF-2α 的肝细胞特异性缺失显着减弱了 PHDi 治疗的这些作用，表明 PHDi 作用是 HIF-2α 依赖性的。在分子水平上，HIF-2α 诱导Irs2增加和环 AMP 特异性磷酸二酯酶基因表达，分别导致胰岛素和胰高血糖素信号增加和减少。PHDi 治疗的这些作用在人和小鼠肝细胞中是保守的。

结论

我们的结果阐明了 PHD 抑制如何通过 HIF-2α 依赖性调节肝脏胰岛素和胰高血糖素敏感性来改善血糖控制的未知机制。