title: Saturated free fatty acid sodium palmitate-induced lipoapoptosis by targeting glycogen synthase kinase-3β activation in human liver cells.
abstract: BACKGROUND
  Elevated serum saturated fatty acid levels and hepatocyte lipoapoptosis are features of nonalcoholic fatty liver disease (NAFLD).
  
  
  OBJECTIVE
  The purpose of this study was to investigate saturated fatty acid induction of lipoapoptosis in human liver cells and the underlying mechanisms.
  
  
  METHODS
  Human liver L02 and HepG2 cells were treated with sodium palmitate, a saturated fatty acid, for up to 48 h with or without lithium chloride, a glycogen synthase kinase-3β (GSK-3β) inhibitor, or GSK-3β shRNA transfection. Transmission electron microscopy was used to detect morphological changes, flow cytometry was used to detect apoptosis, a colorimetric assay was used to detect caspase-3 activity, and western blot analysis was used to detect protein expression.
  
  
  RESULTS
  The data showed that sodium palmitate was able to induce lipoapoptosis in L02 and HepG2 cells. Western blot analysis showed that sodium palmitate activated GSK-3β protein, which was indicated by dephosphorylation of GSK-3β at Ser-9. However, inhibition of GSK-3β activity with lithium chloride treatment or knockdown of GSK-3β expression with shRNA suppressed sodium palmitate-induced lipoapoptosis in L02 and HepG2 cells. On a molecular level, inhibition of GSK-3β expression or activity suppressed sodium palmitate-induced c-Jun-N-terminal kinase (JNK) phosphorylation and Bax upregulation, whereas GSK-3β inhibition did not affect endoplasmic reticulum stress-induced activation of unfolded protein response.
  
  
  CONCLUSIONS
  The present data demonstrated that saturated fatty acid sodium palmitate-induced lipoapoptosis in human liver L02 and HepG2 cells was regulated by GSK-3β activation, which led to JNK activation and Bax upregulation. This finding indicates that GSK-3β inhibition may be a potential therapeutic target to control NAFLD.
authors.affiliation: Department of Gastroenterology and Hepatology, The 2nd Affiliated Hospital of Chongqing Medical University, No. 74 Linjiang Road, Chongqing, 400010, China, 840331cj@163.com.
authors.forename: Jie
authors.initials: J
authors.lastname: Cao
authors.forename: Xiao-Xia
authors.initials: XX
authors.lastname: Feng
authors.forename: Long
authors.initials: L
authors.lastname: Yao
authors.forename: Bo
authors.initials: B
authors.lastname: Ning
authors.forename: Zhao-Xia
authors.initials: ZX
authors.lastname: Yang
authors.forename: Dian-Liang
authors.initials: DL
authors.lastname: Fang
authors.forename: Wei
authors.initials: W
authors.lastname: Shen
mesh_terms: D017209:Apoptosis / Q000187:drug effects*; D053148:Caspase 3 / Q000378:metabolism; D048430:Cell Shape / Q000187:drug effects; D059865:Endoplasmic Reticulum Stress / Q000187:drug effects; D004789:Enzyme Activation; D004791:Enzyme Inhibitors / Q000494:pharmacology; D005234:Fatty Liver / Q000139:chemically induced* / Q000201:enzymology / Q000473:pathology; D038362:Glycogen Synthase Kinase 3 / Q000037:antagonists & inhibitors / Q000235:genetics / Q000378:metabolism*; D000071679:Glycogen Synthase Kinase 3 beta; D056945:Hep G2 Cells; D022781:Hepatocytes / Q000187:drug effects* / Q000201:enzymology / Q000648:ultrastructure; D006801:Humans; D048031:JNK Mitogen-Activated Protein Kinases / Q000378:metabolism; D008099:Liver / Q000187:drug effects* / Q000201:enzymology / Q000648:ultrastructure; D065626:Non-alcoholic Fatty Liver Disease; D019308:Palmitic Acid / Q000633:toxicity*; D010766:Phosphorylation; D034622:RNA Interference; D015398:Signal Transduction / Q000187:drug effects; D013997:Time Factors; D014162:Transfection; D056811:Unfolded Protein Response / Q000187:drug effects; D051028:bcl-2-Associated X Protein / Q000378:metabolism
chemical_list: C494826:BAX protein, human; D004791:Enzyme Inhibitors; D051028:bcl-2-Associated X Protein; D019308:Palmitic Acid; C000605506:GSK3B protein, human; D000071679:Glycogen Synthase Kinase 3 beta; D048031:JNK Mitogen-Activated Protein Kinases; D038362:Glycogen Synthase Kinase 3; C505407:CASP3 protein, human; D053148:Caspase 3