Shiying Liu1, Yue Yin2, Ruili Yu3, Yin Li4, Weizhen Zhang5. 1. Department of Physiology and Pathophysiology, Peking University Health Science Center, Beijing 100191, China. Electronic address: jessica@bjmu.edu.cn. 2. Department of Physiology and Pathophysiology, Peking University Health Science Center, Beijing 100191, China. Electronic address: bingningxingwan@sina.com. 3. Department of Physiology and Pathophysiology, Peking University Health Science Center, Beijing 100191, China. Electronic address: yyyrrrlll@126.com. 4. Department of Physiology and Pathophysiology, Peking University Health Science Center, Beijing 100191, China. Electronic address: yinli@bjmu.edu.cn. 5. Department of Physiology and Pathophysiology, Peking University Health Science Center, Beijing 100191, China; Department of Surgery, University of Michigan Medical Center, Ann Arbor, MI 48109-0346, USA. Electronic address: weizhenzhang@bjmu.edu.cn.
Abstract
BACKGROUND & AIMS: Leucine-rich repeat G-protein-coupled receptor 4 (LGR4) and its ligands R-spondin1-4 (Rspos) have been vastly investigated in embryonic development. The biological functions of Rspos-LGR4 system in liver remains largely unknown. Here, we explored whether it protects hepatocytes against hypoxia/reoxygenation (H/R) induced damage. METHODS: H/R injury was induced by dimethyloxalylglycine (DMOG) in AML12 cells and the effects of Rspo3 on cell proliferation and apoptosis were assessed. Specific shRNAs were used to interfere LGR4 or β-catenin. RESULTS: DMOG caused hepatocytes damage evidenced by increase in HIF-1α, cell death and apoptosis genes p27 and Bax, with concurrent decrease of cell proliferation genes PCNA and CyclinD1. Of all the Rspos, Rspo3 is predominantly expressed in AML12 hepatocytes. Importantly, Rspo3 demonstrated an alteration in a manner similar to proliferation-related genes during H/R injury. Rspo3 pretreatment rendered hepatocytes less vulnerable to DMOG induced H/R injury. Ablation of LGR4 using shRNA attenuated the protective effects of Rspo3. Wnt3a also protected AML12 cells from damages caused by H/R, showing enhanced proliferation activity. Notably, knockdown of β-catenin in hepatocytes completely abolished the effect of Rspo3 pretreatment on the expression levels of PCNA and CyclinD1. CONCLUSION: Rspo3-LGR4 axis protects hepatocytes from H/R injury via activating β-catenin.
BACKGROUND & AIMS:Leucine-rich repeat G-protein-coupled receptor 4 (LGR4) and its ligands R-spondin1-4 (Rspos) have been vastly investigated in embryonic development. The biological functions of Rspos-LGR4 system in liver remains largely unknown. Here, we explored whether it protects hepatocytes against hypoxia/reoxygenation (H/R) induced damage. METHODS: H/R injury was induced by dimethyloxalylglycine (DMOG) in AML12 cells and the effects of Rspo3 on cell proliferation and apoptosis were assessed. Specific shRNAs were used to interfere LGR4 or β-catenin. RESULTS:DMOG caused hepatocytes damage evidenced by increase in HIF-1α, cell death and apoptosis genes p27 and Bax, with concurrent decrease of cell proliferation genes PCNA and CyclinD1. Of all the Rspos, Rspo3 is predominantly expressed in AML12 hepatocytes. Importantly, Rspo3 demonstrated an alteration in a manner similar to proliferation-related genes during H/R injury. Rspo3 pretreatment rendered hepatocytes less vulnerable to DMOG induced H/R injury. Ablation of LGR4 using shRNA attenuated the protective effects of Rspo3. Wnt3a also protected AML12 cells from damages caused by H/R, showing enhanced proliferation activity. Notably, knockdown of β-catenin in hepatocytes completely abolished the effect of Rspo3 pretreatment on the expression levels of PCNA and CyclinD1. CONCLUSION:Rspo3-LGR4 axis protects hepatocytes from H/R injury via activating β-catenin.
Authors: Huai-Xiang Hao; Yang Xie; Yue Zhang; Olga Charlat; Emma Oster; Monika Avello; Hong Lei; Craig Mickanin; Dong Liu; Heinz Ruffner; Xiaohong Mao; Qicheng Ma; Raffaella Zamponi; Tewis Bouwmeester; Peter M Finan; Marc W Kirschner; Jeffery A Porter; Fabrizio C Serluca; Feng Cong Journal: Nature Date: 2012-04-29 Impact factor: 49.962