Department of Anesthesiology, Aichi Medical University School of Medicine, Nagakute, Aichi-gun, Aichi, 480-1195, Japan.
Clin Exp Nephrol. 2010 Jun;14(3):205-12. doi: 10.1007/s10157-010-0276-1. Epub 2010 Mar 12.
Hyperglycemia/high glucose may induce apoptosis in diabetic kidney, but the mechanism is not fully understood. Naofen was found as a Shiga toxin (Stx)-2-related protein. Based on renal dysfunction in infection with Stx-producing Escherichia coli and on participation of naofen in apoptosis of human embryonic kidney cells, the present study was undertaken to investigate the mechanism of renal dysfunction in diabetes mellitus with particular reference to naofen.
In in vivo studies utilizing streptozotocin (STZ)-induced diabetic rats, and also in in vitro cultured rat kidney epithelial (NRK52E) cells, naofen messenger RNA (mRNA) and protein expressions were analyzed. Naofen mRNA location in diabetic kidney was studied by in situ hybridization. Apoptosis was assessed by caspase-3 activity assay.
Rat diabetic kidney showed significant increases in caspase-3 activities and naofen mRNA. Naofen was mainly observed at both proximal and distal urinary tubules. Incubation of NRK52E cells in high glucose medium resulted in elevated naofen mRNA expression, whereas neither interleukin-1, interleukin-6, nor tumor necrosis factor-alpha elicited such action. Moreover, treatment of NRK52E cells with naofen small interfering RNA (siRNA) inhibited naofen mRNA expression induced by high glucose and blocked the increase in caspase-3 activity.
These data suggest that naofen expression may be upregulated by hyperglycemia, with possible correlation to apoptosis of tubular epithelial cells and thereby to diabetic nephropathy.
高血糖/高葡萄糖可能会诱导糖尿病肾病中的细胞凋亡，但机制尚不完全清楚。纳芬被发现与志贺毒素（Stx）-2 相关蛋白有关。基于产志贺毒素大肠杆菌感染导致的肾功能障碍以及纳芬参与人胚肾细胞凋亡的事实，本研究旨在探讨糖尿病肾病中肾功能障碍的机制，特别关注纳芬。
在链脲佐菌素（STZ）诱导的糖尿病大鼠体内研究以及体外培养的大鼠肾上皮（NRK52E）细胞中，分析纳芬信使 RNA（mRNA）和蛋白的表达。通过原位杂交研究糖尿病肾脏中纳芬 mRNA 的定位。通过半胱氨酸天冬氨酸蛋白酶-3（caspase-3）活性测定评估细胞凋亡。
糖尿病大鼠肾脏的 caspase-3 活性和纳芬 mRNA 显著增加。纳芬主要在近端和远端肾小管中观察到。在高葡萄糖培养基中孵育 NRK52E 细胞会导致纳芬 mRNA 表达升高，而白细胞介素-1、白细胞介素-6 或肿瘤坏死因子-α均不会引起这种作用。此外，用纳芬小干扰 RNA（siRNA）处理 NRK52E 细胞可抑制高葡萄糖诱导的纳芬 mRNA 表达，并阻断 caspase-3 活性的增加。
这些数据表明，高血糖可能上调纳芬的表达，与肾小管上皮细胞凋亡有关，从而与糖尿病肾病有关。
