Department of Physiology, Morehouse School of Medicine, Atlanta, GA 30310, USA.
Int J Mol Sci. 2019 Jul 11;20(14):3406. doi: 10.3390/ijms20143406.
Diabetic nephropathy is increasingly recognized as a major contributor to kidney failure in patients with obesity and type 2 diabetes. This study was designed to identify the molecular mediators of kidney injury associated with metabolic syndrome with or without hyperglycemia. We compared renal gene expression profiles in Zucker lean (ZL), Zucker obese (ZO), and Zucker diabetic (ZD) rats using cDNA microarray with quantitative verification of selected transcripts by real-time PCR. Compared to the 20-week-old ZL control (glucose: 110 ± 8 mg/dL), both prediabetic ZO (glucose: 157 ± 11 mg/dL) and diabetic ZD (glucose: 481 ± 37 mg/dL) rats displayed hyperlipidemia and kidney injury with a high degree of proteinuria. cDNA microarray identified 25 inflammation and injury-related transcriptomes whose expression levels were similarly increased in ZO and ZD kidneys. Among them, kidney injury molecule-1 (KIM-1) was found to be the most highly upregulated in both ZO and ZD kidneys. Immunofluorescence staining of kidney sections revealed a strong correlation between lipid overload and KIM-1 upregulation in proximal tubules of ZO and ZD rats. In cultured primary renal tubular epithelial cells (TECs), administration of saturated fatty acid palmitate resulted in an upregulation of KIM-1, osteopontin, and CD44, which was greatly attenuated by U0126, an inhibitor of extracellular signal-regulated kinase (ERK)1/2. Moreover, knockdown of KIM-1 by siRNA interference inhibited palmitate-induced cleaved caspase-3, osteopontin, and CD44 proteins in primary TECs. Our results indicate that KIM-1 expression is upregulated in renal lipotoxicity and may play an important role in fatty acid-induced inflammation and tubular cell damage in obesity and diabetic kidney disease.
糖尿病肾病日益被认为是肥胖和 2 型糖尿病患者肾衰竭的主要原因。本研究旨在鉴定与代谢综合征相关的肾损伤的分子介质，无论是否伴有高血糖。我们使用 cDNA 微阵列比较了 Zucker 瘦（ZL）、Zucker 肥胖（ZO）和 Zucker 糖尿病（ZD）大鼠的肾脏基因表达谱，并通过实时 PCR 对选定的转录本进行了定量验证。与 20 周龄的 ZL 对照组（血糖：110±8mg/dL）相比，糖尿病前期的 ZO（血糖：157±11mg/dL）和糖尿病 ZD（血糖：481±37mg/dL）大鼠均表现出高脂血症和肾脏损伤，蛋白尿程度较高。cDNA 微阵列鉴定出 25 个与炎症和损伤相关的转录组，其在 ZO 和 ZD 肾脏中的表达水平相似增加。其中，肾损伤分子-1（KIM-1）在 ZO 和 ZD 肾脏中表达上调最为明显。肾组织切片免疫荧光染色显示，ZO 和 ZD 大鼠近端肾小管中脂质过载与 KIM-1 上调之间存在强烈相关性。在原代肾小管上皮细胞（TEC）中，饱和脂肪酸棕榈酸的处理导致 KIM-1、骨桥蛋白和 CD44 的表达上调，而 ERK1/2 的抑制剂 U0126 则大大减弱了这一上调。此外，siRNA 干扰敲低 KIM-1 抑制了原代 TEC 中棕榈酸诱导的裂解半胱天冬酶-3、骨桥蛋白和 CD44 蛋白。我们的结果表明，KIM-1 的表达在肾脂毒性中上调，可能在肥胖和糖尿病肾病中脂肪酸诱导的炎症和肾小管细胞损伤中发挥重要作用。
