Enhancement of survival by LPA via Erk1/Erk2 and PI 3-kinase/Akt pathways in a murine hepatocyte cell line.
First published September 5, 2001; 10.1152/ajpcell.00077.2001.-Protective mechanisms for lysophosphatidic acid (LPA) against cell death caused by Clostridium difficile toxin, or tumor necrosis factor-alpha (TNF-alpha) plus D-galactosamine, were investigated in a murine hepatocyte cell line AML12 expressing Edg2 LPA receptor. In these models of hepatocellular injury, LPA prevented hepatocyte damage, suppressed apoptosis, and enhanced cell survival in a dose-dependent fashion. The protective effects of LPA were abolished by wortmannin and LY-294002, specific inhibitors of phosphatidylinositol 3-phosphate kinase (PI 3-kinase), and by PD-98059 and U-0126, inhibitors of MEK1/MEK2. In nontreated hepatocytes, LPA elicited a gradual and sustained increase in phosphorylation of Erk1/Erk2 over 180 min of stimulation and downstream phosphorylation of p90RSK and transcription factor Elk-1. In C. difficile toxin-treated cells, LPA-induced phosphorylation of Erk1/Erk2 was rapid but transient, while p90RSK and Elk-1 phosphorylation did not change significantly. LPA stimulated phosphorylation of Akt in a time-dependent manner in both intact and toxin-treated AML12 hepatocytes. Wortmannin and LY-294002 abolished phosphorylation of Akt, further supporting activation of PI 3-kinase/Akt as a signaling pathway, which mediates hepatocyte protection by LPA. Taken together, these results demonstrate that LPA prevents cell apoptosis induced by C. difficile toxin and TNF-alpha/D-galactosamine in the AML12 murine hepatocyte cell line. Cell protection by LPA involves activation of the mitogen-activated protein kinase Erk1/Erk2 cascade and PI 3-kinase-dependent phosphorylation of Akt.
Sautin
Y Y
YY
Department of Pathology, University of Florida College of Medicine, Gainesville, Florida 32610, USA.
Crawford
J M
JM
Svetlov
S I
SI
D000730:Androstadienes / Q000494:pharmacology; D000818:Animals; D017209:Apoptosis / Q000502:physiology; D001427:Bacterial Toxins / Q000494:pharmacology; D002070:Butadienes / Q000494:pharmacology; D002460:Cell Line; D002867:Chromones / Q000494:pharmacology; D004247:DNA / Q000378:metabolism; D004768:Enterotoxins / Q000494:pharmacology; D004791:Enzyme Inhibitors / Q000494:pharmacology; D005419:Flavonoids / Q000494:pharmacology; D022781:Hepatocytes / Q000166:cytology / Q000187:drug effects* / Q000378:metabolism; D006801:Humans; D008246:Lysophospholipids / Q000494:pharmacology*; D051379:Mice; D008822:Mice, Transgenic; D019950:Mitogen-Activated Protein Kinase 1 / Q000378:metabolism*; D048052:Mitogen-Activated Protein Kinase 3; D020928:Mitogen-Activated Protein Kinases / Q000378:metabolism*; D009025:Morpholines / Q000494:pharmacology; D009570:Nitriles / Q000494:pharmacology; D019869:Phosphatidylinositol 3-Kinases / Q000378:metabolism*; D000081082:Phosphoinositide-3 Kinase Inhibitors; D017346:Protein Serine-Threonine Kinases; D011518:Proto-Oncogene Proteins / Q000378:metabolism*; D051057:Proto-Oncogene Proteins c-akt; D011956:Receptors, Cell Surface / Q000235:genetics / Q000378:metabolism; D043562:Receptors, G-Protein-Coupled; D049368:Receptors, Lysophosphatidic Acid; D016211:Transforming Growth Factor alpha / Q000235:genetics / Q000378:metabolism; D014409:Tumor Necrosis Factor-alpha / Q000494:pharmacology; D000077191:Wortmannin
D000730:Androstadienes; D001427:Bacterial Toxins; D002070:Butadienes; D002867:Chromones; D004247:DNA; D004768:Enterotoxins; D004791:Enzyme Inhibitors; D005419:Flavonoids; D008246:Lysophospholipids; D019950:Mitogen-Activated Protein Kinase 1; D048052:Mitogen-Activated Protein Kinase 3; D020928:Mitogen-Activated Protein Kinases; D009025:Morpholines; D009570:Nitriles; D019869:Phosphatidylinositol 3-Kinases; D000081082:Phosphoinositide-3 Kinase Inhibitors; D017346:Protein Serine-Threonine Kinases; D011518:Proto-Oncogene Proteins; D051057:Proto-Oncogene Proteins c-akt; D011956:Receptors, Cell Surface; D043562:Receptors, G-Protein-Coupled; D049368:Receptors, Lysophosphatidic Acid; D016211:Transforming Growth Factor alpha; D014409:Tumor Necrosis Factor-alpha; D000077191:Wortmannin; C113580:U 0126; C041348:tcdA protein, Clostridium difficile; C085911:2-(4-morpholinyl)-8-phenyl-4H-1-benzopyran-4-one; C494918:AKT1 protein, human; C093973:2-(2-amino-3-methoxyphenyl)-4H-1-benzopyran-4-one