Liu Xin1, Wu Fan1, Du Tingting1, Sun Zuoming2, Zhang Qiang3. 1. Geriatrics, Institute of Gerontology of Tianjin, Tianjin Medical University General Hospital, No.154, Anshan Road, Heping District, Tianjin, China. 2. Beckman Research Institute of the City of Hope, Duarte, CA, USA. 3. Geriatrics, Institute of Gerontology of Tianjin, Tianjin Medical University General Hospital, No.154, Anshan Road, Heping District, Tianjin, China. zhangqiangyulv@163.com.
Abstract
PURPOSE: To investigate the effect of 4-phenylbutyric acid (4-PBA) on intermittent hypoxia (IH)-induced liver cell injury and to clarify the underlying mechanisms. METHODS: L02 cells (normal human liver cells) were cultured in normoxic condition or subjected to intermittent hypoxia for 4, 8, and 12 h. A part of hypoxia-treated L02 cells was applied with 4-PBA 1 h before exposure to hypoxia. The effect of 4-PBA on liver injury, hepatocyte apoptosis, endoplasmic reticulum stress (ERS), and PERK-eIFa2-ATF4-CHOP apoptotic pathway was investigated. RESULTS: (1) IH caused apoptosis in hepatocyte; (2) IH caused ERS in hepatocyte; (3) IH caused hepatic injury; (4) 4-PBA attenuated IH-induced liver cell injury; (5) 4-PBA protected liver cell from IH-induced apoptosis; (6) 4-PBA suppressed ERS-related apoptotic pathway (PERK-eIFa2-ATF4-CHOP), but did not suppress IH-induced unfold protein reaction (UPR). CONCLUSIONS: 4-PBA could protect liver cells by suppressing IH-induced apoptosis mediated by ERS, but not by reducing the UPR.
PURPOSE: To investigate the effect of 4-phenylbutyric acid (4-PBA) on intermittent hypoxia (IH)-induced liver cell injury and to clarify the underlying mechanisms. METHODS: L02 cells (normal human liver cells) were cultured in normoxic condition or subjected to intermittent hypoxia for 4, 8, and 12 h. A part of hypoxia-treated L02 cells was applied with 4-PBA 1 h before exposure to hypoxia. The effect of 4-PBA on liver injury, hepatocyte apoptosis, endoplasmic reticulum stress (ERS), and PERK-eIFa2-ATF4-CHOP apoptotic pathway was investigated. RESULTS: (1) IH caused apoptosis in hepatocyte; (2) IH caused ERS in hepatocyte; (3) IH caused hepatic injury; (4) 4-PBA attenuated IH-induced liver cell injury; (5) 4-PBA protected liver cell from IH-induced apoptosis; (6) 4-PBA suppressed ERS-related apoptotic pathway (PERK-eIFa2-ATF4-CHOP), but did not suppress IH-induced unfold protein reaction (UPR). CONCLUSIONS:4-PBA could protect liver cells by suppressing IH-induced apoptosis mediated by ERS, but not by reducing the UPR.
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