title: Map kinase and PKC signaling pathways modulate NGF-mediated apoE transcription.
abstract: The present study assessed the mechanisms by which nerve growth factor (NGF) increased the level of apolipoprotein E (apoE) in PC12 cells. NGF (50ng/mL) significantly increased apoE protein levels following 72h of treatment. Similarly NGF increased luciferase activity in cells transfected with a luciferase reporter construct containing a 500bp fragment of the apoE promoter, indicating NGF-induced apoE expression is regulated, at least in part, at the level of transcription. The non-selective nitric oxide synthase (NOS) inhibitor N(ɷ)-nitro-L-arginine methylester (L-NAME; 20mM) did not attenuate the NGF-mediated increase in luciferase activity, while the inducible NOS inhibitor s-methylisothiourea (S-MIU; 2mM) partially attenuated this action of NGF. Inhibition of MAP kinase activation with 50μM U0126 or pre-treatment with the PKC inhibitor bisindolylmaleimide 1 (BIS-1; 10μM) prevented the NGF-mediated activation of the apoE promoter. Pre-treatment with the phospholipase C (PLC) inhibitor U73122 (5μM) partially inhibited the NGF-induced increase in luciferase activity while the Akt inhibitor LY294002 (10μM) had no effect. These data suggest NGF-induced apoE transcription requires MAP kinase and PKC activation and that these TrkA signaling pathways may be modulated by NO.
authors: Department of Biomedical Sciences, University of Guelph, Guelph, ON N1G 2W1, Canada.
authors: Megan R
authors: MR
authors: Strachan-Whaley
authors: Department of Biomedical Sciences, University of Guelph, Guelph, ON N1G 2W1, Canada.
authors: Kate
authors: K
authors: Reilly
authors: Department of Biomedical Sciences, University of Guelph, Guelph, ON N1G 2W1, Canada.
authors: James
authors: J
authors: Dobson
authors: Department of Biomedical Sciences, University of Guelph, Guelph, ON N1G 2W1, Canada. Electronic address: bkalisch@uoguelph.ca.
authors: Bettina E
authors: BE
authors: Kalisch
mesh_terms: D000818:Animals; D001057:Apolipoproteins E / Q000235:genetics* / Q000378:metabolism; D002867:Chromones / Q000494:pharmacology; D004963:Estrenes / Q000494:pharmacology; D007211:Indoles / Q000494:pharmacology; D007550:Isothiuronium / Q000031:analogs & derivatives / Q000494:pharmacology; D008301:Maleimides / Q000494:pharmacology; D020928:Mitogen-Activated Protein Kinases / Q000378:metabolism*; D009025:Morpholines / Q000494:pharmacology; D019331:NG-Nitroarginine Methyl Ester / Q000494:pharmacology; D020932:Nerve Growth Factor / Q000378:metabolism* / Q000494:pharmacology; D052247:Nitric Oxide Synthase Type II / Q000037:antagonists & inhibitors / Q000378:metabolism; D016716:PC12 Cells; D011401:Promoter Regions, Genetic; D011493:Protein Kinase C / Q000037:antagonists & inhibitors / Q000378:metabolism*; D051057:Proto-Oncogene Proteins c-akt / Q000037:antagonists & inhibitors; D011760:Pyrrolidinones / Q000494:pharmacology; D051381:Rats; D015398:Signal Transduction; D014158:Transcription, Genetic; D010738:Type C Phospholipases / Q000037:antagonists & inhibitors
chemical_list: D001057:Apolipoproteins E; D002867:Chromones; D004963:Estrenes; D007211:Indoles; D008301:Maleimides; D009025:Morpholines; D011760:Pyrrolidinones; C060229:1-(6-((3-methoxyestra-1,3,5(10)-trien-17-yl)amino)hexyl)-1H-pyrrole-2,5-dione; D007550:Isothiuronium; C085911:2-(4-morpholinyl)-8-phenyl-4H-1-benzopyran-4-one; D020932:Nerve Growth Factor; D052247:Nitric Oxide Synthase Type II; D051057:Proto-Oncogene Proteins c-akt; D011493:Protein Kinase C; D020928:Mitogen-Activated Protein Kinases; D010738:Type C Phospholipases; C027744:S-methylisothiopseudouronium; C088060:bisindolylmaleimide; D019331:NG-Nitroarginine Methyl Ester
keywords: Apolipoprotein E (apoE); Nerve growth factor (NGF); Nitric oxide (NO); PC12 cells; Signal transduction