Reddy V Sudhakar, Pandarinath S, Archana M, Reddy G Bhanuprakash
Biochemistry Division, ICMR-National Institute of Nutrition, Hyderabad, India.
Biochemistry Division, ICMR-National Institute of Nutrition, Hyderabad, India.
Arch Biochem Biophys. 2021 Apr 15;701:108816. doi: 10.1016/j.abb.2021.108816. Epub 2021 Feb 23.
Small heat shock proteins (sHsps) are a family of proteins. Some are induced in response to multiple stimuli and others are constitutively expressed. They are involved in fundamental cellular processes, including protein folding, apoptosis, and maintenance of cytoskeletal integrity. Hyperglycemia created during diabetes leads to neuronal derangements in the brain. In this study, we investigated the impact of chronic hyperglycemia on the expression of sHsps and heat shock transcription factors (HSFs), solubility and aggregation of sHsps and amyloidogenic proteins, and their role in neuronal apoptosis in a diabetic rat model. Diabetes was induced in Sprague-Dawley rats with streptozotocin and hyperglycemia was maintained for 16 weeks. Expressions of sHsps and HSFs were analyzed by qRT-PCR and immunoblotting in the cerebral cortex. Solubility of sHsps and amyloidogenic proteins, including α-synuclein and Tau, was analyzed by the detergent soluble assay. Neuronal cell death was analyzed by TUNEL staining and apoptotic markers. The interaction of sHsps with amyloidogenic proteins and Bax was assessed using co-immunoprecipitation. Hyperglycemia decreased Hsp27 and HSF1, and increased αBC, Hsp22, and HSF4 levels at transcript and protein levels. Diabetes induced the aggregation of αBC, Hsp22, α-synuclein, and pTau, as their levels were higher in the insoluble fraction. Additionally, diabetes impaired the interaction of αBC with α-synuclein and pTau. Furthermore, diabetes reduced the interaction of αBC with Bax, which may possibly contribute to neuronal apoptosis. Together, these results indicate that chronic hyperglycemia induces differential responses of sHsps by altering their expression, solubility, interaction, and roles in apoptosis.
小热休克蛋白（sHsps）是一类蛋白质。有些是在多种刺激下诱导产生的，而另一些则是组成型表达的。它们参与基本的细胞过程，包括蛋白质折叠、细胞凋亡和细胞骨架完整性的维持。糖尿病期间产生的高血糖会导致大脑中的神经元紊乱。在本研究中，我们在糖尿病大鼠模型中研究了慢性高血糖对sHsps和热休克转录因子（HSFs）表达、sHsps和淀粉样蛋白的溶解性与聚集以及它们在神经元凋亡中的作用的影响。用链脲佐菌素诱导Sprague-Dawley大鼠患糖尿病，并使高血糖状态维持16周。通过qRT-PCR和免疫印迹分析大脑皮层中sHsps和HSFs的表达。通过去污剂可溶性分析来分析sHsps和淀粉样蛋白（包括α-突触核蛋白和Tau蛋白）的溶解性。通过TUNEL染色和凋亡标志物分析神经元细胞死亡情况。使用免疫共沉淀评估sHsps与淀粉样蛋白和Bax的相互作用。高血糖在转录和蛋白质水平上降低了Hsp27和HSF1的水平，并增加了αBC、Hsp22和HSF4的水平。糖尿病诱导了αBC、Hsp22、α-突触核蛋白和pTau的聚集，因为它们在不溶性部分中的水平较高。此外，糖尿病损害了αBC与α-突触核蛋白和pTau的相互作用。此外，糖尿病减少了αBC与Bax的相互作用，这可能导致神经元凋亡。总之，这些结果表明慢性高血糖通过改变sHsps的表达、溶解性、相互作用及其在凋亡中的作用来诱导其产生不同的反应。
