Lipotoxicity is a pivotal factor that initiates and exacerbates liver injury and is involved in the development of metabolic-associated fatty liver disease(MAFLD).However,there are few reported lipotoxicity inhibitors...Lipotoxicity is a pivotal factor that initiates and exacerbates liver injury and is involved in the development of metabolic-associated fatty liver disease(MAFLD).However,there are few reported lipotoxicity inhibitors.Here,we identified a natural anti-lipotoxicity candidate,HN-001,from the marine fungus Aspergillus sp.C1.HN-001 dose-and time-dependently reversed palmitic acid(PA)-induced hepatocyte death.This protection was associated with IRE-1a-mediated XBP-1 splicing inhibition,which resulted in suppression of XBP-1s nuclear translocation and transcriptional regulation.Knockdown of XBP-1s attenuated lipotoxicity,but no additional ameliorative effect of HN-001 on lipotoxicity was observed in XBP-1s knockdown hepatocytes.Notably,the ER stress and lipotoxicity amelioration was associated with PLA2.Both HN-001 and the PLA2 inhibitor MAFP inhibited PLA2 activity,reduced lysophosphatidylcholine(LPC)level,subsequently ameliorated lipotoxicity.In contrast,overexpression of PLA2 caused exacerbation of lipotoxicity and weakened the anti-lipotoxic effects of HN-001.Additionally,HN-001 treatment suppressed the downstream pro-apoptotic JNK pathway.In vivo,chronic administration of HN-001(i.p.)in mice alleviated all manifestations of MAFLD,including hepatic steatosis,liver injury,inflammation,and fibrogenesis.These effects were correlated with PLA2/IRE-1a/XBP-1s axis and JNK signaling suppression.These data indicate that HN-001 has therapeutic potential for MAFLD because it suppresses lipotoxicity,and provide a natural structural basis for developing anti-MAFLD candidates.展开更多
The endoplasmic reticulum-nuclei-1 (ERN1) sensing and signaling enzyme mediates a set of complex intracellular signaling events known as the unfolded protein response. We have studied the effect of hypoxia and ischemi...The endoplasmic reticulum-nuclei-1 (ERN1) sensing and signaling enzyme mediates a set of complex intracellular signaling events known as the unfolded protein response. We have studied the effect of hypoxia and ischemic conditions (glucose or glutamine deprivation) on the expression of several casein kinase-1 and -2 genes in glioma U87 cells and its subline with suppressed function of ERN1. It was shown that blockade of ERN1, the key endoplasmic reticulum stress sensor, leads to an increase in the expression levels of casein kinase-1G2, -1E, -2B and NUCKS1 mRNA, but suppresses casein kinase-1A1, -1D and -2A1. Moreover, the expression levels of casein kinase-1A1, -1D and 1G3 as well as casein kinase-2A1 and -2A2 mRNAs are significantly increased under glutamine dep- rivation conditions both in control and ERN1- deficient glioma cells. At the same time, casein kinase-1E, -2B and NUCKS1 mRNA expression levels are also increased under this condition, but only in cells with suppressed function of ERN1. The expression level of NUCKS1 mRNA, however, is decreased both in control glioma cells and in genetically modified cells, but casein kinase-1G2—only in control U87 cells. Cell exposure to glucose deprivation conditions enhances the expression levels of casein kinase- 1D, 1G3, -1E and -2A1 in both types of glioma cells used, but casein kinase-2B expression levels increase only in cells with suppressed function of ERN1. Hypoxia induces or suppresses the expression of most of the studied genes mainly in ERN1-knockdown cells only. Results of this study show that hypoxia as well as glutamine and glucose deprivation conditions change the expression level most of casein kinase genes and that these effects are dependent on ERN1 signaling enzyme function.展开更多
基金This study was supported by National Natural Science Foundation of China(82260674 to Yong Rao,82160653 to Ling Huang)Fundamental Research Funds for Hainan University(KYQD(ZR)-21114 to Yong Rao,KYQD(ZR)-21089 to Ling Huang,China)+2 种基金Hainan Provincial Natural Science Foundation of China(822MS054 to Yong Rao)Natural Science Foundation of Guangdong Province(2021A1515010488 to Yong Rao,China)Central Public-interest Scientific Institution Basal Research Fund for CATAS-ITBB(1630052022016,1630052019011,China).
文摘Lipotoxicity is a pivotal factor that initiates and exacerbates liver injury and is involved in the development of metabolic-associated fatty liver disease(MAFLD).However,there are few reported lipotoxicity inhibitors.Here,we identified a natural anti-lipotoxicity candidate,HN-001,from the marine fungus Aspergillus sp.C1.HN-001 dose-and time-dependently reversed palmitic acid(PA)-induced hepatocyte death.This protection was associated with IRE-1a-mediated XBP-1 splicing inhibition,which resulted in suppression of XBP-1s nuclear translocation and transcriptional regulation.Knockdown of XBP-1s attenuated lipotoxicity,but no additional ameliorative effect of HN-001 on lipotoxicity was observed in XBP-1s knockdown hepatocytes.Notably,the ER stress and lipotoxicity amelioration was associated with PLA2.Both HN-001 and the PLA2 inhibitor MAFP inhibited PLA2 activity,reduced lysophosphatidylcholine(LPC)level,subsequently ameliorated lipotoxicity.In contrast,overexpression of PLA2 caused exacerbation of lipotoxicity and weakened the anti-lipotoxic effects of HN-001.Additionally,HN-001 treatment suppressed the downstream pro-apoptotic JNK pathway.In vivo,chronic administration of HN-001(i.p.)in mice alleviated all manifestations of MAFLD,including hepatic steatosis,liver injury,inflammation,and fibrogenesis.These effects were correlated with PLA2/IRE-1a/XBP-1s axis and JNK signaling suppression.These data indicate that HN-001 has therapeutic potential for MAFLD because it suppresses lipotoxicity,and provide a natural structural basis for developing anti-MAFLD candidates.
文摘The endoplasmic reticulum-nuclei-1 (ERN1) sensing and signaling enzyme mediates a set of complex intracellular signaling events known as the unfolded protein response. We have studied the effect of hypoxia and ischemic conditions (glucose or glutamine deprivation) on the expression of several casein kinase-1 and -2 genes in glioma U87 cells and its subline with suppressed function of ERN1. It was shown that blockade of ERN1, the key endoplasmic reticulum stress sensor, leads to an increase in the expression levels of casein kinase-1G2, -1E, -2B and NUCKS1 mRNA, but suppresses casein kinase-1A1, -1D and -2A1. Moreover, the expression levels of casein kinase-1A1, -1D and 1G3 as well as casein kinase-2A1 and -2A2 mRNAs are significantly increased under glutamine dep- rivation conditions both in control and ERN1- deficient glioma cells. At the same time, casein kinase-1E, -2B and NUCKS1 mRNA expression levels are also increased under this condition, but only in cells with suppressed function of ERN1. The expression level of NUCKS1 mRNA, however, is decreased both in control glioma cells and in genetically modified cells, but casein kinase-1G2—only in control U87 cells. Cell exposure to glucose deprivation conditions enhances the expression levels of casein kinase- 1D, 1G3, -1E and -2A1 in both types of glioma cells used, but casein kinase-2B expression levels increase only in cells with suppressed function of ERN1. Hypoxia induces or suppresses the expression of most of the studied genes mainly in ERN1-knockdown cells only. Results of this study show that hypoxia as well as glutamine and glucose deprivation conditions change the expression level most of casein kinase genes and that these effects are dependent on ERN1 signaling enzyme function.
