Department of Physiology, University of Louisville School of Medicine, Louisville, KY 40202, USA.
Biomolecules. 2021 Oct 7;11(10):1477. doi: 10.3390/biom11101477.
Diabetic kidney is associated with an accumulation of extracellular matrix (ECM) leading to renal fibrosis. Dysregulation of retinoic acid metabolism involving retinoic acid receptors (RARs) and retinoid X receptors (RXRs) has been shown to play a crucial role in diabetic nephropathy (DN). Furthermore, RARs and peroxisome proliferator-activated receptor γ (PPARγ) are known to control the RXR-mediated transcriptional regulation of several target genes involved in DN. Recently, RAR and RXR have been shown to upregulate plasminogen activator inhibitor-1 (PAI-1), a major player involved in ECM accumulation and renal fibrosis during DN. Interestingly, hydrogen sulfide (HS) has been shown to ameliorate adverse renal remodeling in DN. We investigated the role of RXR signaling in the ECM turnover in diabetic kidney, and whether HS can mitigate ECM accumulation by modulating PPAR/RAR-mediated RXR signaling. We used wild-type (C57BL/6J), diabetic (C57BL/6-/J) mice and mouse mesangial cells (MCs) as experimental models. GYY4137 was used as a HS donor. Results showed that in diabetic kidney, the expression of PPARγ was decreased, whereas upregulations of RXRα, RXRβ, and RARγ1 expression were observed. The changes were associated with elevated PAI-1, MMP-9 and MMP-13. In addition, the expressions of collagen IV, fibronectin and laminin were increased, whereas elastin expression was decreased in the diabetic kidney. Excessive collagen deposition was observed predominantly in the peri-glomerular and glomerular regions of the diabetic kidney. Immunohistochemical localization revealed elevated expression of fibronectin and laminin in the glomeruli of the diabetic kidney. GYY4137 reversed the pathological changes. Similar results were observed in in vitro experiments. In conclusion, our data suggest that RXR signaling plays a significant role in ECM turnover, and GYY4137 modulates PPAR/RAR-mediated RXR signaling to ameliorate PAI-1-dependent adverse ECM turnover in DN.
糖尿病肾病与细胞外基质(ECM)的积累有关,导致肾纤维化。已经表明,视黄酸代谢的失调涉及视黄酸受体(RARs)和视黄醛 X 受体(RXRs),在糖尿病肾病(DN)中起着至关重要的作用。此外,RAR 和过氧化物酶体增殖物激活受体γ(PPARγ)已知控制 RXR 介导的几种参与 DN 的靶基因的转录调节。最近,已经表明 RAR 和 RXR 上调纤溶酶原激活物抑制剂-1(PAI-1),PAI-1 是参与 DN 期间 ECM 积累和肾纤维化的主要因子。有趣的是,已经表明硫化氢(HS)可以改善 DN 中的不良肾重塑。我们研究了 RXR 信号在糖尿病肾脏 ECM 周转中的作用,以及 HS 是否可以通过调节 PPAR/RAR 介导的 RXR 信号来减轻 ECM 积累。我们使用野生型(C57BL/6J)、糖尿病(C57BL/6-/-J)小鼠和小鼠系膜细胞(MCs)作为实验模型。GYY4137 用作 HS 供体。结果表明,在糖尿病肾脏中,PPARγ 的表达降低,而 RXRα、RXRβ 和 RARγ1 的表达上调。这些变化与 PAI-1、MMP-9 和 MMP-13 的升高有关。此外,在糖尿病肾脏中,胶原 IV、纤维连接蛋白和层粘连蛋白的表达增加,而弹性蛋白的表达减少。在糖尿病肾脏中,主要在肾小球周围和肾小球区域观察到过多的胶原沉积。免疫组织化学定位显示,糖尿病肾脏肾小球中纤维连接蛋白和层粘连蛋白的表达增加。GYY4137 逆转了病理变化。在体外实验中也观察到了类似的结果。总之,我们的数据表明,RXR 信号在 ECM 周转中起着重要作用,GYY4137 调节 PPAR/RAR 介导的 RXR 信号,以改善 DN 中依赖 PAI-1 的不良 ECM 周转。