title: ER calcium discharge stimulates GDNF gene expression through MAPK-dependent and -independent pathways in rat C6 glioblastoma cells.
abstract: Glial cell line-derived neurotrophic factor (GDNF), a neurotrophic and differentiation factor, is expressed under several pathophysiological conditions but its regulatory signals have not yet been clarified. Here, we found that endoplasmic reticulum (ER) Ca(2+) discharge by thapsigargin induced GDNF mRNA as well as COX2 and GRP78 expression in rat C6 glioblastoma cells. GDNF mRNA was immediately induced and peaked at 2h by thapsigargin, and the alternative transcript consisting of exon 3 and exon 4 appeared to be most inducible. In spite of intracellular Ca(2+) perturbation, Ca(2+)-dependent PKC was not responsible for this induction. Instead, a PKCdelta-specific inhibitor, rottlerin, suppressed the thapsigargin-induced GDNF mRNA expression. On the other hand, thapsigargin transiently enhanced phosphorylation status of mitogen-activated protein kinase (MAPK) pathway, including extracellular signal-regulated kinase (Erk), p38 MAPK and c-JUN amino-terminal kinase1 (JNK1) simultaneously; whereas specific inhibitors against MEK1 and JNK only reduced the thapsigargin-induced GDNF mRNA expression. In addition, a pan-PKC inhibitor (Ro-31-8220) attenuated the thapsigargin-enhanced phosphorylation levels of Erk1/2 and JNK1, whereas rottlerin did not. Thus, the present study demonstrated that the thapsigargin-stimulated ER Ca(2+) discharge up-regulated GDNF gene expression through both MAPK-dependent and -independent pathways in C6 glioblastoma cells.
authors.affiliation: Department of Biomolecular Science, Faculty of Engineer, Gifu University, 1-1 Yanagido, Gifu 501-1193, Japan.
authors.forename: Kentaro
authors.initials: K
authors.lastname: Oh-hashi
authors.forename: Masayo
authors.initials: M
authors.lastname: Kaneyama
authors.forename: Yoko
authors.initials: Y
authors.lastname: Hirata
authors.forename: Kazutoshi
authors.initials: K
authors.lastname: Kiuchi
mesh_terms: D000818:Animals; D002118:Calcium / Q000502:physiology*; D045744:Cell Line, Tumor; D051546:Cyclooxygenase 2 / Q000096:biosynthesis; D004721:Endoplasmic Reticulum / Q000502:physiology*; D048049:Extracellular Signal-Regulated MAP Kinases / Q000378:metabolism; D051100:Glial Cell Line-Derived Neurotrophic Factor / Q000096:biosynthesis* / Q000235:genetics; D005909:Glioblastoma; D006360:Heat-Shock Proteins / Q000096:biosynthesis; D048055:Mitogen-Activated Protein Kinase 8 / Q000378:metabolism; D020928:Mitogen-Activated Protein Kinases / Q000502:physiology*; D018832:Molecular Chaperones / Q000096:biosynthesis; D010766:Phosphorylation; D011493:Protein Kinase C / Q000502:physiology; D012333:RNA, Messenger / Q000096:biosynthesis; D051381:Rats; D019284:Thapsigargin / Q000494:pharmacology; D015854:Up-Regulation; D048051:p38 Mitogen-Activated Protein Kinases / Q000378:metabolism; D000091342:Endoplasmic Reticulum Chaperone BiP
chemical_list: D002118:Calcium; D051546:Cyclooxygenase 2; D048049:Extracellular Signal-Regulated MAP Kinases; D051100:Glial Cell Line-Derived Neurotrophic Factor; D006360:Heat-Shock Proteins; D048055:Mitogen-Activated Protein Kinase 8; D020928:Mitogen-Activated Protein Kinases; D018832:Molecular Chaperones; D011493:Protein Kinase C; D012333:RNA, Messenger; D019284:Thapsigargin; D048051:p38 Mitogen-Activated Protein Kinases; C051684:GRP78 protein, rat; D000091342:Endoplasmic Reticulum Chaperone BiP; C489691:Ptgs2 protein, rat