Int J Biol Sci 2022; 18(1):96-111. doi:10.7150/ijbs.64665 This issue

Research Paper

GPR43 activation-mediated lipotoxicity contributes to podocyte injury in diabetic nephropathy by modulating the ERK/EGR1 pathway

Jian Lu1, Pei Pei Chen1, Jia Xiu Zhang1, Xue Qi Li1, Gui Hua Wang1, Ben Yin Yuan1, Si Jia Huang1, Xiao Qi Liu1, Ting Ting Jiang1, Meng Ying Wang1, Wen Tao Liu1, Xiong Zhong Ruan2, Bi Cheng Liu1, Kun Ling Ma1✉

1. Institute of Nephrology, Zhongda Hospital, School of Medicine, Southeast University, Nanjing, 210009, China.
2. John Moorhead Research Laboratory, Department of Renal Medicine, University College London (UCL) Medical School, Royal Free Campus, London, NW3 2PF, UK.

This is an open access article distributed under the terms of the Creative Commons Attribution License (https://creativecommons.org/licenses/by/4.0/). See http://ivyspring.com/terms for full terms and conditions.
Citation:
Lu J, Chen PP, Zhang JX, Li XQ, Wang GH, Yuan BY, Huang SJ, Liu XQ, Jiang TT, Wang MY, Liu WT, Ruan XZ, Liu BC, Ma KL. GPR43 activation-mediated lipotoxicity contributes to podocyte injury in diabetic nephropathy by modulating the ERK/EGR1 pathway. Int J Biol Sci 2022; 18(1):96-111. doi:10.7150/ijbs.64665. Available from https://www.ijbs.com/v18p0096.htm

File import instruction

Abstract

Graphic abstract

Background: G-protein-coupled receptor 43 (GPR43) is a posttranscriptional regulator involved in cholesterol metabolism. This study aimed to investigate the possible roles of GPR43 activation in podocyte lipotoxicity in diabetic nephropathy (DN) and explore the potential mechanisms.

Methods: The experiments were conducted by using diabetic GPR43-knockout mice and a podocyte cell culture model. Lipid deposition and free cholesterol levels in kidney tissues were measured by BODIPY staining and quantitative cholesterol assays, respectively. The protein expression of GPR43, LC3II, p62, beclin1, low-density lipoprotein receptor (LDLR) and early growth response protein 1 (EGR1) in kidney tissues and podocytes was measured by real-time PCR, immunofluorescent staining and Western blotting.

Results: There were increased LDL cholesterol levels in plasma and cholesterol accumulation in the kidneys of diabetic mice. However, GPR43 gene knockout inhibited these changes. An in vitro study further demonstrated that acetate treatment induced cholesterol accumulation in high glucose-stimulated podocytes, which was correlated with increased cholesterol uptake mediated by LDLR and reduced cholesterol autophagic degradation, as characterized by the inhibition of LC3 maturation, p62 degradation and autophagosome formation. Gene knockdown or pharmacological inhibition of GPR43 prevented these effects on podocytes. Furthermore, GPR43 activation increased extracellular regulated protein kinases 1/2 (ERK1/2) activity and EGR1 expression in podocytes, which resulted in an increase in cholesterol influx and autophagy inhibition. In contrast, after GPR43 deletion, these changes in podocytes were improved, as shown by the in vivo and in vitro results.

Conclusion: GPR43 activation-mediated lipotoxicity contributes to podocyte injury in DN by modulating the ERK/EGR1 pathway.

Keywords: diabetic nephropathy, podocytes, lipotoxicity, GPR43, autophagy, low-density lipoprotein receptor