Yong Su1, Qingqing Chen2, Yinghui Ju3, Weizu Li4, Weiping Li5. 1. Department of Pharmacy, The First Affiliated Hospital of Anhui Medical University, Hefei 230032, Anhui, China; Key Laboratory of Anti-Inflammatory and Immunopharmacology, Ministry of Education, Department of Pharmacology, Anhui Medical University, Hefei 230032, Anhui, China. 2. Key Laboratory of Anti-Inflammatory and Immunopharmacology, Ministry of Education, Department of Pharmacology, Anhui Medical University, Hefei 230032, Anhui, China. 3. Department of Pharmacy, Hefei Ion Medical Center, Hefei 230032, Anhui, China. 4. Key Laboratory of Anti-Inflammatory and Immunopharmacology, Ministry of Education, Department of Pharmacology, Anhui Medical University, Hefei 230032, Anhui, China. Electronic address: liweizu@126.com. 5. Key Laboratory of Anti-Inflammatory and Immunopharmacology, Ministry of Education, Department of Pharmacology, Anhui Medical University, Hefei 230032, Anhui, China; Anqing Medical and Pharmaceutical College, Anqing 246052, Anhui, China. Electronic address: lwp19@126.com.
Abstract
BACKGROUND: Our previous study suggested that palmitate (PA) induces human glomerular mesangial cells (HMCs) fibrosis. However, the mechanism is not fully understood. Recent studies suggested that transient receptor potential canonical channel 6 (TRPC6)/nuclear factor of activated T cell 2 (NFAT2) played an important role in renal fibrosis. Moreover, cluster of differentiation 36 (CD36) regulated the synthesis of TPRC6 agonist diglyceride. In the present study, we investigated whether PA induced HMCs fibrosis via TRPC6/NFAT2 mediated by CD36. METHODS: A type 2 diabetic nephropathy (DN) model was established in Sprague Dawley rats, and HMCs were stimulated with PA. Lipid accumulation and free fatty acid (FFA) uptake were measured. The expression levels of TGF-β1, p-Smad2/3, FN, TRPC6, NFAT2 and CD36 were evaluated. The intracellular calcium concentration ([Ca2+]i) was assessed. RESULTS: FFA were elevated in type 2 DN rats with kidney fibrosis in addition to NFAT2 and CD36 expression. In vitro, PA induced HMCs fibrosis, [Ca2+]i elevation and NFAT2 activation. SKF96365 or TRPC6-siRNA could attenuate PA-induced HMCs damage. By contrast, the TRPC6 activator showed the opposite effect. Moreover, NFAT2-siRNA also suppressed PA-induced HMCs fibrosis. CD36 knockdown inhibited the PA-induced [Ca2+]i elevation and NFAT2 expression. In addition, long-term treatment with PA decreased TRPC6 expression in HMCs. CONCLUSION: The results of this study demonstrated that PA could induce the activation of the [Ca2+]i/NFAT2 signaling pathway through TRPC6, which led to HMCs fibrosis. Although activation of TRPC6 attributed to CD36-mediated lipid deposition, long-term stimulation of PA may lead to negative feedback on the expression of TPRC6.
BACKGROUND: Our previous study suggested that palmitate (PA) induces human glomerular mesangial cells (HMCs) fibrosis. However, the mechanism is not fully understood. Recent studies suggested that transient receptor potential canonical channel 6 (TRPC6)/nuclear factor of activated T cell 2 (NFAT2) played an important role in renal fibrosis. Moreover, cluster of differentiation 36 (CD36) regulated the synthesis of TPRC6 agonist diglyceride. In the present study, we investigated whether PA induced HMCs fibrosis via TRPC6/NFAT2 mediated by CD36. METHODS: A type 2 diabetic nephropathy (DN) model was established in Sprague Dawley rats, and HMCs were stimulated with PA. Lipid accumulation and free fatty acid (FFA) uptake were measured. The expression levels of TGF-β1, p-Smad2/3, FN, TRPC6, NFAT2 and CD36 were evaluated. The intracellular calcium concentration ([Ca2+]i) was assessed. RESULTS:FFA were elevated in type 2 DN rats with kidney fibrosis in addition to NFAT2 and CD36 expression. In vitro, PA induced HMCs fibrosis, [Ca2+]i elevation and NFAT2 activation. SKF96365 or TRPC6-siRNA could attenuate PA-induced HMCs damage. By contrast, the TRPC6 activator showed the opposite effect. Moreover, NFAT2-siRNA also suppressed PA-induced HMCs fibrosis. CD36 knockdown inhibited the PA-induced [Ca2+]i elevation and NFAT2 expression. In addition, long-term treatment with PA decreased TRPC6 expression in HMCs. CONCLUSION: The results of this study demonstrated that PA could induce the activation of the [Ca2+]i/NFAT2 signaling pathway through TRPC6, which led to HMCs fibrosis. Although activation of TRPC6 attributed to CD36-mediated lipid deposition, long-term stimulation of PA may lead to negative feedback on the expression of TPRC6.