Animal model studies show that reductive stress is involved in cardiomyopathy and myopathy, but the exact physiological relevance remains unknown. In addition, the microRNAs miR-143 and miR-145 have been shown to be upregulated in cardiac diseases, but the underlying mechanisms associated with these regulators have yet to be explored. We developed transgenic mouse lines expressing exogenous miR-143 and miR-145 under the control of the alpha-myosin heavy chain (αMHC) promoter/enhancer. The two transgenic lines showed dilated cardiomyopathy-like characteristics and early lethality with markedly increased expression of miR-143. The expression of hexokinase 2 (HK2), a cardioprotective gene that is a target of miR-143, was strongly suppressed in the transgenic hearts, but the in vitro HK activity and adenosine triphosphate (ATP) content were comparable to those observed in wild-type mice. In addition, transgenic complementation of HK2 expression did not reduce mortality rates. Although HK2 is crucial for the pentose phosphate pathway (PPP) and glycolysis, the ratio of reduced glutathione (GSH) to oxidized glutathione (GSSG) was unexpectedly higher in the hearts of transgenic mice. The expression of gamma-glutamylcysteine synthetase heavy subunit (γ-GCSc) and the in vitro activity of glutathione reductase (GR) were also higher, suggesting that the recycling of GSH and its de novo biosynthesis were augmented in transgenic hearts. Furthermore, the expression levels of glucose-6-phosphate dehydrogenase (G6PD, a rate-limiting enzyme for the PPP) and p62/SQSTM1 (a potent inducer of glycolysis and glutathione production) were elevated, while p62/SQSTM1 was upregulated at the mRNA level rather than as a result of autophagy inhibition. Consistent with this observation, nuclear factor erythroid-2 related factor 2 (Nrf2), Jun N-terminal kinase (JNK) and inositol-requiring enzyme 1 alpha (IRE1α) were activated, all of which are known to induce p62/SQSTM1 expression. Overexpression of miR-143 and miR-145 leads to a unique dilated cardiomyopathy phenotype with a reductive redox shift despite marked downregulation of HK2 expression. Reductive stress may be involved in a wider range of cardiomyopathies than previously thought.

中文翻译：

---

miR-143 和 -145 在心肌细胞中的强制表达可诱导心肌病，并具有还原性氧化还原位移。

动物模型研究表明，减少性应激与心肌病和肌病有关，但确切的生理相关性仍然未知。此外，已显示 microRNA miR-143 和 miR-145 在心脏病中上调，但与这些调节剂相关的潜在机制仍有待探索。我们开发了在 α-肌球蛋白重链 (αMHC) 启动子/增强子控制下表达外源 miR-143 和 miR-145 的转基因小鼠系。这两个转基因系表现出扩张型心肌病样特征和早期致死率，miR-143 的表达显着增加。己糖激酶 2 (HK2) 是一种心脏保护基因，是 miR-143 的靶标，在转基因心脏中的表达受到强烈抑制，但体外 HK 活性和三磷酸腺苷 (ATP) 含量与在野生型小鼠中观察到的相当。此外，HK2 表达的转基因互补并没有降低死亡率。尽管 HK2 对戊糖磷酸途径 (PPP) 和糖酵解至关重要，但在转基因小鼠的心脏中，还原型谷胱甘肽 (GSH) 与氧化型谷胱甘肽 (GSSG) 的比例出乎意料地高。γ-谷氨酰半胱氨酸合成酶重亚基 (γ-GCSc) 的表达和谷胱甘肽还原酶 (GR) 的体外活性也较高，表明 GSH 的再循环及其从头生物合成在转基因心脏中增强。此外，葡萄糖-6-磷酸脱氢酶 (G6PD, PPP 的限速酶）和 p62/SQSTM1（糖酵解和谷胱甘肽产生的强效诱导剂）升高，而 p62/SQSTM1 在 mRNA 水平上调，而不是由于自噬抑制。与这一观察结果一致，核因子红细胞 2 相关因子 2 (Nrf2)、Jun N 末端激酶 (JNK) 和肌醇需要酶 1 α (IRE1α) 被激活，所有这些都已知会诱导 p62/SQSTM1 表达。尽管 HK2 表达显着下调，但 miR-143 和 miR-145 的过表达导致独特的扩张型心肌病表型具有还原性氧化还原转变。减少性压力可能涉及比以前认为的更广泛的心肌病。与这一观察结果一致，核因子红细胞 2 相关因子 2 (Nrf2)、Jun N 末端激酶 (JNK) 和肌醇需要酶 1 α (IRE1α) 被激活，所有这些都已知会诱导 p62/SQSTM1 表达。尽管 HK2 表达显着下调，但 miR-143 和 miR-145 的过表达导致独特的扩张型心肌病表型具有还原性氧化还原转变。减少性压力可能涉及比以前认为的更广泛的心肌病。与这一观察结果一致，核因子红细胞 2 相关因子 2 (Nrf2)、Jun N 末端激酶 (JNK) 和肌醇需要酶 1 α (IRE1α) 被激活，所有这些都已知会诱导 p62/SQSTM1 表达。尽管 HK2 表达显着下调，但 miR-143 和 miR-145 的过表达导致独特的扩张型心肌病表型具有还原性氧化还原转变。减少性压力可能涉及比以前认为的更广泛的心肌病。尽管 HK2 表达显着下调，但 miR-143 和 miR-145 的过表达导致独特的扩张型心肌病表型具有还原性氧化还原转变。减少性压力可能涉及比以前认为的更广泛的心肌病。尽管 HK2 表达显着下调，但 miR-143 和 miR-145 的过表达导致独特的扩张型心肌病表型具有还原性氧化还原转变。减少性压力可能涉及比以前认为的更广泛的心肌病。