Mortuza Rokhsana, Feng Biao, Chakrabarti Subrata
Department of Pathology, Schulich School of Medicine & Dentistry, University of Western Ontario, London, ON, Canada.
J Cell Mol Med. 2015 Aug;19(8):1857-67. doi: 10.1111/jcmm.12557. Epub 2015 Mar 6.
In diabetes, hyperglycaemia causes up-regulation of endothelin 1 (ET-1) and transforming growth factor beta 1 (TGF-β1). Previously we showed glucose reduces sirtuin1 (SIRT1), a class III histone deacetylase. Here, we investigated the regulatory role of SIRT1 on ET-1 and TGF-β1 expression. Human microvascular endothelial cells were examined following incubation with 25 mmol/l glucose (HG) and 5 mmol/l glucose (NG) with or without SIRT1 or histone acetylase p300 overexpression or knockdown. mRNA expressions of ET-1, TGF-β1, SIRT1, p300 and collagen 1α(I) were examined. SIRT1 enzyme activity, ET-1 and TGF-β1 protein levels were measured. Histone acetylation and endothelial permeability were further investigated. Similar analyses were performed in the kidneys and retinas of SIRT1 overexpressing transgenic mice with or without streptozotocin induced diabetes. Renal functions were evaluated. In the endothelial cells (ECs), HG caused increased permeability and escalated production of ET-1, TGF-β1, collagen Iα(I). These cells also showed increased p300 expression, histone acetylation and reduced SIRT1 levels. These changes were rectified in the ECs following p300 silencing or by SIRT1 overexpression, whereas SIRT1 knockdown or p300 overexpression in NG mimicked the effects of HG. High ET-1 and TGF-β1 levels were seen in the kidneys and retinas of diabetic mice along with micro-albuminuria and increased fibronectin protein (marker of glucose-induced cell injury) levels. Interestingly, these detrimental changes were blunted in SIRT1 overexpressing transgenic mice with diabetes. This study showed a novel SIRT1 mediated protection against renal and retinal injury in diabetes, regulated through p300, ET-1 and TGF-β1.
在糖尿病中，高血糖会导致内皮素1（ET-1）和转化生长因子β1（TGF-β1）上调。此前我们发现葡萄糖会降低Ⅲ类组蛋白去乙酰化酶沉默调节蛋白1（SIRT1）的水平。在此，我们研究了SIRT1对ET-1和TGF-β1表达的调节作用。用25 mmol/L葡萄糖（HG）和5 mmol/L葡萄糖（NG）孵育人微血管内皮细胞，同时过表达或敲低SIRT1或组蛋白乙酰化酶p300，然后检测这些细胞。检测ET-1、TGF-β1、SIRT1、p300和胶原蛋白1α（I）的mRNA表达。测定SIRT1酶活性、ET-1和TGF-β1蛋白水平。进一步研究组蛋白乙酰化和内皮通透性。在有或无链脲佐菌素诱导糖尿病的SIRT1过表达转基因小鼠的肾脏和视网膜中进行类似分析。评估肾功能。在内皮细胞（ECs）中，HG导致通透性增加，ET-1、TGF-β1、胶原蛋白Iα（I）的产生增加。这些细胞还表现出p300表达增加、组蛋白乙酰化增加和SIRT1水平降低。在ECs中，p300沉默或SIRT1过表达后这些变化得到纠正，而在NG中SIRT1敲低或p300过表达则模拟了HG的作用。糖尿病小鼠的肾脏和视网膜中ET-1和TGF-β1水平较高，同时伴有微量白蛋白尿和纤连蛋白蛋白（葡萄糖诱导细胞损伤的标志物）水平升高。有趣的是，在患有糖尿病的SIRT1过表达转基因小鼠中，这些有害变化得到了缓解。这项研究表明，SIRT1通过p300、ET-1和TGF-β1介导对糖尿病肾和视网膜损伤的新型保护作用。
