The role of mitochondrial unfolded protein response in palmitic acid-induced lipid accumulation in renal tubule epithelium in vitro / 西安交通大学学报(医学版)

【Objective】 To investigate the effect of mitochondrial unfolded protein response (UPRmt) on lipid metabolism in human kidney 2 (HK-2) cells . 【Methods】 Lipid accumulation was induced by palmitic acid (PA) in HK-2 cells. The cells were pretreated with siRNA or CDDO respectively. The intracellular lipid accumulation was observed by oil red staining; mitochondrial membrane potential (MMP) was measured by JC-1.The contents of reactive oxygen species (ROS) in mitochondria were measured by Mito-SOX, and the expressions of HSP60, LONP1, CLPP, ACOX1, PPARα, PGC1α and CPT1α were detected by Western blotting. 【Results】 PA induced lipid aggregation, MMP decrease, ROS generation in mitochondria and the decreased expression of UPRmt proteins (e. g., HSP60 and LONP1) in HK-2 cells. Pretreatment of HK-2 cells with siRNA could aggravate lipid aggregation, MMP decrease and ROS generation induced by PA, and further decrease the expression of HSP 60and LONP1.Pretreatment of HK-2 cells with CDDO alleviated lipid aggregation, MMP decrease, ROS generation and decreased HSP60 and LONP1 expressions induced by PA. 【Conclusion】 Lipid aggregation in HK-2 cells induced by PA may be related to mitochondrial dysfunction and UPRmt has a protective effect on HK-2 cells in the process.

Protective effects of total saponins of Panax japonicas on HepG2 cell apoptosis induced with palmitic acid / 中国中药杂志

This study aimed to investigate the molecular mechanism and protective effect of total saponins of Panax japonicas (TSPJ) on HepG2 cells apoptosis induced by palmitic acid (PA).The HepG2 cells were cultured , and divided into five groups: the control group, the model group, the high-dose group (50 mg·L⁻¹), the middle-dose group (25 mg·L⁻¹) and the low-dose group (12.5 mg·L⁻¹).The cells of the five groups were cultured continuously for 24 hours. The cell viability was measured with MTT. HepG2 cells apoptosis was detected by Hoechest staining and Annexin V-FITC/PI staining. The protein expressions of BCL-2, CHOP and TLR4 were measured with western blotting and flow cytometry analysis. The mRNA expressions of TNF-α, IL-1β, BCL-2, CHOP and GAPDH were measured with RT-PCR. The results suggested that compared with the control group, the number of HepG2 cells of the model group were reduced significantly (<0.01), while the number of apoptotic HepG2 cells were increased. Compared with the model group, the number of HepG2 cells of the high-dose group and the middle-dose group were increased significantly (<0.01), whereas the number of apoptotic HepG2 cells were reduced. Compared with the control group, TNF-α, IL-1β and CHOP mRNA expressions and CHOP and TLR4 protein expressions in the model group were significantly up-regulated (<0.01), while BCL-2 protein and mRNA expressions in the model group were significantly decreased (<0.01). Compared with the model group, TNF-α, IL-1β and CHOP mRNA expressions and CHOP and TLR4 protein expressions in the high-dose group were significantly decreased (<0.01), while BCL-2 protein and mRNA expressions in the high-dose group were significantly up-regulated (<0.01).In conclusion, TSPJ can reduce inflammation and apoptosis induced by palmitic acid, with a certain protective effect on liver cells.

Ethanol promotes saturated fatty acid-induced hepatoxicity through endoplasmic reticulum (ER) stress response / 中国天然药物

Serum palmitic acid (PA), a type of saturated fatty acid, causes lipid accumulation and induces toxicity in hepatocytes. Ethanol (EtOH) is metabolized by the liver and induces hepatic injury and inflammation. Herein, we analyzed the effects of EtOH on PA-induced lipotoxicity in the liver. Our results indicated that EtOH aggravated PA-induced apoptosis and lipid accumulation in primary rat hepatocytes in dose-dependent manner. EtOH intensified PA-caused endoplasmic reticulum (ER) stress response in vitro and in vivo, and the expressions of CHOP, ATF4, and XBP-1 in nucleus were significantly increased. EtOH also increased PA-caused cleaved caspase-3 in cytoplasm. In wild type and CHOP(-/-) mice treated with EtOH and high fat diet (HFD), EtOH worsened the HFD-induced liver injury and dyslipidemia, while CHOP knockout blocked toxic effects of EtOH and PA. Our study suggested that targeting UPR-signaling pathways is a promising, novel approach to reducing EtOH and saturated fatty acid-induced metabolic complications.