Yu Xiaoyan, Su Qing, Geng Jianan, Liu Hui, Liu Yumeng, Liu Jinming, Shi Yan, Zou Yinggang
Department of Experimental Pharmacology and Toxicology, School of Pharmaceutical Sciences, Jilin University, Changchun, Jilin 130021, P.R. China.
Department of Anatomy, College of Basic Medical Science, Jilin University, Changchun, Jilin 130012, P.R. China.
Exp Ther Med. 2021 Apr;21(4):333. doi: 10.3892/etm.2021.9764. Epub 2021 Feb 8.
The present study aimed to investigate the preventive effects of leaf extract (GBE) against extracellular matrix (ECM) accumulation in a streptozotocin (STZ)-induced rat model of diabetic nephropathy (DN), and to determine its underlying molecular mechanism. , a rat model of DN was established by intraperitoneal injection of STZ, and the rats were subsequently administered GBE. The results demonstrated that GBE significantly decreased blood glucose, the urine protein excretion rate and ECM accumulation in DN rats. In addition, the development of DN significantly induced tissue transglutaminase (tTG) protein expression, which was detected by immunohistochemistry, western blotting and PCR analyses, while GBE administration decreased tTG expression in the diabetic kidney. , rat glomerular mesangial cells (HBZY-1 cells) cultured with high glucose were also treated with GBE. The concentrations of tTG, fibronectin, type IV collagen, transforming growth factor (TGF)-β and connective tissue growth factor (CTGF) were detected via ELISA. The results demonstrated that GBE notably decreased the concentration of these proteins, and tTG expression was positively associated with TGF-β. GBE also suppressed tTG expression of high glucose-treated HBZY-1 cells in a concentration-dependent manner. Furthermore, tTG protein expression was detected in high glucose-treated HBZY-1 cells transfected with small interfering RNA (siRNA) oligonucleotides against TGF-β and CTGF to investigate a possible mechanism of GBE-mediated inhibition of tTG. The results demonstrated that the tTG levels remained unchanged in CTGF siRNA-transfected cells, but were decreased in the GBE + CTGF siRNA group compared with the control siRNA group, suggesting that tTG may not be regulated by CTGF, and the inhibitory effect of GBE on tTG may not be associated with the direct inhibition of CTGF. However, tTG expression was decreased following the transfection with TGF-β siRNA, in which levels of tTG were similar compared with both the GBE group and GBE + TGF-β siRNA group, indicating that tTG may be regulated by TGF-β, and that the GBE-induced repression of tTG expression may be associated with the downregulation of TGF-β. Taken together, the results of the present study suggest that GBE prevented ECM accumulation by suppressing tTG expression in DN, which was predominantly mediated by TGF-β.
本研究旨在探讨银杏叶提取物（GBE）对链脲佐菌素（STZ）诱导的糖尿病肾病（DN）大鼠模型细胞外基质（ECM）积聚的预防作用，并确定其潜在的分子机制。通过腹腔注射STZ建立DN大鼠模型，随后给大鼠施用GBE。结果表明，GBE显著降低了DN大鼠的血糖、尿蛋白排泄率和ECM积聚。此外，DN的发展显著诱导了组织转谷氨酰胺酶（tTG）蛋白表达，通过免疫组织化学、蛋白质印迹和PCR分析检测到，而施用GBE降低了糖尿病肾脏中tTG的表达。用高糖培养的大鼠肾小球系膜细胞（HBZY-1细胞）也用GBE处理。通过ELISA检测tTG、纤连蛋白、IV型胶原、转化生长因子（TGF）-β和结缔组织生长因子（CTGF）的浓度。结果表明，GBE显著降低了这些蛋白质的浓度，并且tTG表达与TGF-β呈正相关。GBE还以浓度依赖的方式抑制高糖处理的HBZY-1细胞的tTG表达。此外，在用针对TGF-β和CTGF的小干扰RNA（siRNA）寡核苷酸转染的高糖处理的HBZY-1细胞中检测tTG蛋白表达，以研究GBE介导的tTG抑制的可能机制。结果表明，CTGF siRNA转染细胞中tTG水平保持不变，但与对照siRNA组相比，GBE + CTGF siRNA组中tTG水平降低，表明tTG可能不受CTGF调节，并且GBE对tTG的抑制作用可能与对CTGF的直接抑制无关。然而，用TGF-β siRNA转染后tTG表达降低，其中tTG水平与GBE组和GBE + TGF-β siRNA组相似，表明tTG可能受TGF-β调节，并且GBE诱导的tTG表达抑制可能与TGF-β的下调有关。综上所述，本研究结果表明，GBE通过抑制DN中tTG的表达来预防ECM积聚，这主要由TGF-β介导。
