title: C-Fos regulation by the MAPK and PKC pathways in intervertebral disc cells.
abstract: BACKGROUND
  The gene encoding c-fos is an important factor in the pathogenesis of joint disease in patients with osteoarthritis. However, it is unknown whether the signal mechanism of c-fos acts in intervertebral disc (IVD) cells. We investigated whether c-fos is activated in relation to mitogen-activated protein kinases (MAPKs) and the protein kinase C (PKC) pathway in nucleus pulposus (NP) cells.
  
  
  RESULTS
  Reverse transcription-polymerase chain reaction and western blotting analyses were used to measure the expression of c-fos in rat IVD cells. Transfections were performed to determine the effects of c-fos on target gene activity. The effect of c-fos protein expression was examined in transfection experiments and in a 3- (4,5-dimethylthiazol-2-yl) -2,5-diphenyltetrazolium bromide cell viability assay. Phorbol 12-myristate 13-acetate (PMA), the most commonly used phorbol ester, binds to and activates protein kinase C (PKC), causing a wide range of effects in cells and tissues. PMA induced the expression of c-fos gene transcription and protein expression, and led to activation of the MAPK pathways in NP cells. The c-fos promoter was suppressed completely in the presence of the MAPK inhibitor PD98059, an inhibitor of the MEK/ERK kinase cascade, but not in the presence of SKF86002, SB202190, or SP600125. The effects of the PKC pathway on the transcriptional activity of the c-fos were evaluated. PKCγ and PKCδ suppressed the promoter activity of c-fos. Treatment with c-fos inhibited aggrecan and Col2 promoter activities and the expression of these genes in NP cells.
  
  
  CONCLUSIONS
  This study demonstrated, for the first time, that the MAPK and PKC pathways had opposing effects on the regulation of c-fos in NP cells. Thus, the expression of c-fos can be suppressed in the extracellular matrix of NP cells.
authors.affiliation: Department of Orthopaedic Surgery, Surgical Science, Tokai University School of Medicine, Kanagawa, Japan ; Research Center for Regenerative Medicine, Tokai University School of Medicine, Kanagawa, Japan.
authors.forename: Katsuya
authors.initials: K
authors.lastname: Yokoyama
authors.forename: Akihiko
authors.initials: A
authors.lastname: Hiyama
authors.forename: Fumiyuki
authors.initials: F
authors.lastname: Arai
authors.forename: Tadashi
authors.initials: T
authors.lastname: Nukaga
authors.forename: Daisuke
authors.initials: D
authors.lastname: Sakai
authors.forename: Joji
authors.initials: J
authors.lastname: Mochida
mesh_terms: D000818:Animals; D049109:Cell Proliferation / Q000187:drug effects; D005109:Extracellular Matrix / Q000187:drug effects / Q000378:metabolism; D005260:Female; D007403:Intervertebral Disc / Q000166:cytology* / Q000473:pathology; D055959:Intervertebral Disc Degeneration / Q000235:genetics / Q000378:metabolism / Q000473:pathology; D020935:MAP Kinase Signaling System / Q000187:drug effects; D020928:Mitogen-Activated Protein Kinases / Q000378:metabolism*; D011493:Protein Kinase C / Q000378:metabolism*; D051745:Protein Kinase C-delta / Q000378:metabolism; D016760:Proto-Oncogene Proteins c-fos / Q000235:genetics / Q000378:metabolism*; D051381:Rats; D017207:Rats, Sprague-Dawley; D013755:Tetradecanoylphorbol Acetate / Q000494:pharmacology; D018808:Transcription Factor AP-1 / Q000378:metabolism; D014158:Transcription, Genetic / Q000187:drug effects
chemical_list: D016760:Proto-Oncogene Proteins c-fos; D018808:Transcription Factor AP-1; D011493:Protein Kinase C; D051745:Protein Kinase C-delta; D020928:Mitogen-Activated Protein Kinases; D013755:Tetradecanoylphorbol Acetate
references.citation: Oncogene. 1990 Jan;5(1):69-73
references.pmid: 2108403
references.citation: J Orthop Res. 2008 May;26(5):589-600
references.pmid: 18203202
references.citation: Int J Biochem Cell Biol. 2006;38(7):1181-90
references.pmid: 16483831
references.citation: Spine J. 2005 Jan-Feb;5(1):14-23
references.pmid: 15653081
references.citation: J Cell Sci. 1992 Dec;103 ( Pt 4):881-7
references.pmid: 1487501
references.citation: J Bone Miner Res. 2007 Jul;22(7):965-74
references.pmid: 17371162
references.citation: Nat Rev Cancer. 2003 Nov;3(11):859-68
references.pmid: 14668816
references.citation: Spine (Phila Pa 1976). 2007 Nov 1;32(23):2521-8
references.pmid: 17978649
references.citation: Curr Opin Cell Biol. 1998 Apr;10(2):205-19
references.pmid: 9561845
references.citation: Methods Enzymol. 1991;201:340-7
references.pmid: 1719345
references.citation: J Orthop Res. 2011 Jan;29(1):14-9
references.pmid: 20661932
references.citation: J Mol Med (Berl). 1996 Oct;74(10):589-607
references.pmid: 8912180
references.citation: J Biol Chem. 2001 Aug 24;276(34):32094-100
references.pmid: 11402055
references.citation: Arthritis Rheum. 2010 Oct;62(10):3036-47
references.pmid: 20533544
references.citation: EMBO J. 1991 Sep;10(9):2437-50
references.pmid: 1714376
references.citation: J Cell Biol. 1993 Aug;122(3):685-701
references.pmid: 8335693
references.citation: Cell. 1987 Jun 19;49(6):729-39
references.pmid: 3034432
references.citation: Genes Dev. 2003 Jul 1;17(13):1663-76
references.pmid: 12842914
references.citation: J Bone Joint Surg Am. 2006 Apr;88 Suppl 2:21-4
references.pmid: 16595438
references.citation: J Bone Miner Res. 2010 May;25(5):1179-90
references.pmid: 19961337
references.citation: J Biol Chem. 2008 Nov 7;283(45):31163-71
references.pmid: 18784083
references.citation: Endocrine. 1995 Aug;3(8):579-84
references.pmid: 21153135
references.citation: J Cell Physiol. 2009 Dec;221(3):609-17
references.pmid: 19725071
references.citation: J Orthop Res. 2007 Dec;25(12):1574-81
references.pmid: 17593536
references.citation: J Cell Biochem. 2012 May;113(5):1599-607
references.pmid: 22174178
references.citation: J Orthop Res. 2008 Jul;26(7):991-8
references.pmid: 18302237
references.citation: Oncogene. 2001 Apr 30;20(19):2438-52
references.pmid: 11402339
references.citation: Science. 1994 Oct 21;266(5184):443-8
references.pmid: 7939685
references.citation: Cell. 1995 Jan 27;80(2):179-85
references.pmid: 7834738
references.citation: J Bone Joint Surg Am. 2006 Apr;88 Suppl 2:10-4
references.pmid: 16595436
references.citation: J Cell Sci. 2000 Feb;113 ( Pt 3):439-50
references.pmid: 10639331
references.citation: FEBS Lett. 1996 Mar 4;381(3):222-6
references.pmid: 8601460
references.citation: Oncogene. 2001 Apr 30;20(19):2390-400
references.pmid: 11402335
references.citation: Spine (Phila Pa 1976). 2005 Nov 15;30(22):2503-9
references.pmid: 16284587
references.citation: Nat Rev Cancer. 2002 Jun;2(6):465-9
references.pmid: 12189388
references.citation: J Orthop Res. 2010 May;28(5):623-30
references.pmid: 19953600
references.citation: FEBS Lett. 2001 Mar 9;492(1-2):39-44
references.pmid: 11248233
references.citation: Clin Biomech (Bristol, Avon). 2001 Nov;16(9):728-34
references.pmid: 11714549
references.citation: Nature. 1984 Apr 19-25;308(5961):693-8
references.pmid: 6232463
references.citation: Matrix Biol. 2006 Sep;25(7):409-18
references.pmid: 16934445
references.citation: J Biol Chem. 1985 Jul 5;260(13):8026-31
references.pmid: 2989273
references.citation: J Orthop Res. 2012 Sep;30(9):1478-85
references.pmid: 22389031
references.citation: Spine (Phila Pa 1976). 2000 Dec 1;25(23):3005-13
references.pmid: 11145811
references.citation: J Biol Chem. 2006 Jan 20;281(3):1381-8
references.pmid: 16293629
references.citation: Proc Natl Acad Sci U S A. 1997 Apr 15;94(8):3994-9
references.pmid: 9108093