Department of Pharmacy, Birla Institute of Technology and Sciences (BITS) Pilani, Hyderabad Campus, Jawahar Nagar, Shameerpet, Hyderabad, Telangana 500078, India.
Department of Molecular Biology, Central University of Jammu, India.
Biochem Pharmacol. 2020 Jul;177:113948. doi: 10.1016/j.bcp.2020.113948. Epub 2020 Apr 3.
Protein Kinase R (PKR) plays a key role in inflammation and insulin resistance. Cytokines, high fat diet, infection and various stress signals can activate PKR. However, the functional significance of PKR in diabetic cardiomyopathy (DCM) is not explored so far. Thus the aim of the present study was to investigate the role of PKR in DCM in vivo in a rat model of DCM and underlying molecular mechanism.
DCM was induced in Wistar rats by recipe of high fat diet and single injection of streptozotocin. Vital parameters were measured by non-invasive BP apparatus. Morphology, fibrosis and protein expression in heart was done by haematoxylin & eosin staining, masson's trichome/sirius red staining and western blotting respectively. For molecular mechanism studies, PKR gene silencing was done in cultured H9C2 cardiomyocytes and effect was observed in the presence of high glucose and high fat. Significant upregulation of PKR along with increase in cardiac biomarkers, decreased systolic and diastolic cardiac functions, oxidative stress, inflammatory markers, markers of fibrosis, enhanced cell death and AGEs' was observed in DCM disease model. Moreover, selective inhibition of PKR alleviated cardiac dysfunction, fibrosis, oxidative stress, inflammation and cell death. Additionally knockdown of PKR attenuated glucolipotoxicty-induced markers of inflammation, oxidative stress and apoptosis in cultured H9C2 cardiomyocytes.
Our present study reports for the first time that inhibition of PKR may have great therapeutic potential in the treatment of DCM by attenuating inflammation, oxidative stress, apoptosis and fibrosis.
蛋白激酶 R（PKR）在炎症和胰岛素抵抗中发挥关键作用。细胞因子、高脂肪饮食、感染和各种应激信号都可以激活 PKR。然而，PKR 在糖尿病心肌病（DCM）中的功能意义尚未得到探索。因此，本研究旨在体内研究 DCM 大鼠模型中 PKR 在 DCM 中的作用及其潜在的分子机制。
通过高脂肪饮食和链脲佐菌素单次注射的配方在 Wistar 大鼠中诱导 DCM。非侵入性血压仪测量生命参数。通过苏木精和伊红染色、马松三色染色/天狼猩红染色和 Western 印迹分别对心脏的形态、纤维化和蛋白表达进行检测。为了进行分子机制研究，在培养的 H9C2 心肌细胞中进行 PKR 基因沉默，并在高葡萄糖和高脂肪存在的情况下观察其作用。在 DCM 疾病模型中观察到 PKR 的显著上调，同时伴随着心脏生物标志物的增加、收缩和舒张心脏功能降低、氧化应激、炎症标志物、纤维化标志物、细胞死亡增加和 AGEs 的增加。此外，选择性抑制 PKR 可减轻心脏功能障碍、纤维化、氧化应激、炎症和细胞死亡。此外，PKR 的敲低可减轻培养的 H9C2 心肌细胞中糖脂毒性诱导的炎症、氧化应激和细胞凋亡标志物。
本研究首次报道，抑制 PKR 可能通过减轻炎症、氧化应激、细胞凋亡和纤维化，在 DCM 的治疗中具有很大的治疗潜力。
