Gao Sumin, Qiu Yun, Meng Yuming, Jia Yajuan, Lang Xuemei, Zhao Hongmei, Sun Hong, Zhang Jinsong, Ding Lianshu
Department of Emergency Medicine, The Affiliated Huaian NO.1 People's Hospital of Nanjing Medical University, Huai'an, China.
Department of Emergency Medicine, The First Affiliated Hospital of Nanjing Medical University, Nanjing, China.
J Bioenerg Biomembr. 2023 Oct;55(5):325-339. doi: 10.1007/s10863-023-09977-4. Epub 2023 Aug 16.
Diabetes can exacerbate myocardial ischemia/reperfusion (IR) injury. However, the sensitivity to IR injury and the underlying mechanisms in diabetic hearts remain unclear. Inhibition of PH domain leucine-rich repeating protein phosphatase (PHLPP1) could reduce myocardial IR injury, our previous study demonstrated that the expression of PHLPP1 was upregulated in diabetic myocardial IR model. Thus, this study aimed to investigate the mechanism of PHLPP1 in diabetic myocardial IR injury. Nondiabetic and diabetic C57BL/6 mice underwent 45 min of coronary artery occlusion followed by 2 h of reperfusion. Male C57BL/6 mice were injected with streptozotocin for five consecutive days to establish a diabetes model. H9c2 cells were exposed to normal or high glucose and subjected to 4 h of hypoxia followed by 4 h of reoxygenation. Diabetes or hyperglycemia increased postischemic infarct size, cellular injury, release of creatine kinase-MB, apoptosis, and oxidative stress, while exacerbating mitochondrial dysfunction. This was accompanied by enhanced expression of PHLPP1 and decreased levels of p-STAT3 and p-Akt. These effects were counteracted by PHLPP1 knockdown. Moreover, PHLPP1 knockdown resulted in an increase in mitochondrial translocation of p-STAT3 Ser727 and nuclear translocation of p-STAT3 Tyr705 and p-STAT3 Ser727. However, the effect of PHLPP1 knockdown in reducing posthypoxic cellular damage was nullified by either Stattic or LY294002. Additionally, a co-immunoprecipitation assay indicated a direct interaction between PHLPP1 and p-STAT3 Ser727, but not p-STAT3 Tyr705. The abnormal expression of PHLPP1 plays a significant role in exacerbating myocardial IR injury in diabetic mice. Knockdown of PHLPP1 to activate the STAT3 signaling pathway may represent a novel strategy for alleviating myocardial IR injury in diabetes.
糖尿病会加重心肌缺血/再灌注（IR）损伤。然而，糖尿病心脏对IR损伤的敏感性及其潜在机制仍不清楚。抑制含PH结构域富亮氨酸重复蛋白磷酸酶（PHLPP1）可减轻心肌IR损伤，我们之前的研究表明，在糖尿病心肌IR模型中PHLPP1的表达上调。因此，本研究旨在探讨PHLPP1在糖尿病心肌IR损伤中的作用机制。将非糖尿病和糖尿病C57BL/6小鼠冠状动脉结扎45分钟，随后再灌注2小时。雄性C57BL/6小鼠连续五天注射链脲佐菌素以建立糖尿病模型。将H9c2细胞置于正常或高糖环境中，缺氧4小时，随后复氧4小时。糖尿病或高血糖会增加缺血后梗死面积、细胞损伤、肌酸激酶-MB释放、细胞凋亡和氧化应激，同时加剧线粒体功能障碍。这伴随着PHLPP1表达增强以及p-STAT3和p-Akt水平降低。这些效应可被PHLPP1基因敲低所抵消。此外，PHLPP1基因敲低导致p-STAT3 Ser727的线粒体易位以及p-STAT3 Tyr705和p-STAT3 Ser727的核易位增加。然而，Stattic或LY294002可消除PHLPP1基因敲低对减轻缺氧后细胞损伤的作用。此外，免疫共沉淀试验表明PHLPP1与p-STAT3 Ser727之间存在直接相互作用，但与p-STAT3 Tyr705不存在直接相互作用。PHLPP1的异常表达在加重糖尿病小鼠心肌IR损伤中起重要作用。敲低PHLPP1以激活STAT3信号通路可能是减轻糖尿病心肌IR损伤的一种新策略。
