title: Influence of Ras and retinoic acid on nerve growth factor induction of transin gene expression in PC12 cells.
abstract: Nerve growth factor (NGF)- and ras-induced neuronal differentiation of PC12 cells is accompanied by expression of transin, a secreted metalloproteinase. Retinoic acid (RA) is known to exert important effects on neural cell proliferation and differentiation. In this study we have analysed different PC12 sublines which express either activated Ras or dominant negative p21N17 Ras, to evaluate the influence of retinoic acid (RA) on the response of the transin gene to NGF and Ras. There was a good correlation between neurite extension and induction of transin mRNA levels in the different subclones. NGF did not induce transin mRNA in cells which do not differentiate in response to this neurotrophin. In addition, incubation with RA did not detectably increase basal transin mRNA levels, but caused a significant increase in the transin response to NGF or Ras in cells in which these factors induce a neuronal morphology. Sequences contained within 750 base pairs of the 5' flanking region of the transin gene confer responsiveness to NGF and Ras, but do not mediate the stimulatory effect of RA. In addition, expression of oncogenic Raf increases transin promoter activity in PC12 cells, but a dominant-negative Raf mutant was unable to block NGF-induced transin activity suggesting the existence of a bifurcation downstream of ras in the signaling mechanism leading to transin expression by NGF.
authors.affiliation: Instituto de Investigaciones Biomédicas, Consejo Superior de Investigaciones Cientificas, Madrid, Spain.
authors.forename: J M
authors.initials: JM
authors.lastname: Cosgaya
authors.forename: J A
authors.initials: JA
authors.lastname: Recio
authors.forename: A
authors.initials: A
authors.lastname: Aranda
mesh_terms: D000818:Animals; D002454:Cell Differentiation / Q000187:drug effects; D002999:Clone Cells; D005786:Gene Expression Regulation / Q000187:drug effects; D019278:Matrix Metalloproteinase 3 / Q000235:genetics*; D009414:Nerve Growth Factors / Q000494:pharmacology*; D009474:Neurons / Q000166:cytology; D016716:PC12 Cells; D011401:Promoter Regions, Genetic; D017346:Protein Serine-Threonine Kinases / Q000502:physiology; D011518:Proto-Oncogene Proteins / Q000502:physiology; D019908:Proto-Oncogene Proteins c-raf; D016283:Proto-Oncogene Proteins p21(ras) / Q000494:pharmacology*; D012333:RNA, Messenger / Q000235:genetics; D051381:Rats; D015398:Signal Transduction; D014212:Tretinoin / Q000494:pharmacology*
chemical_list: D009414:Nerve Growth Factors; D011518:Proto-Oncogene Proteins; D012333:RNA, Messenger; D014212:Tretinoin; D017346:Protein Serine-Threonine Kinases; D019908:Proto-Oncogene Proteins c-raf; D019278:Matrix Metalloproteinase 3; D016283:Proto-Oncogene Proteins p21(ras)