title: Identification and activation of mitogen-activated protein (MAP) kinase in normal human osteoblastic and bone marrow stromal cells: attenuation of MAP kinase activation by cAMP, parathyroid hormone and forskolin.
abstract: The mitogen-activated protein (MAP) kinases (p44mapk and p42mapk), also known as extracellular signal-regulated kinases 1 and 2 (ERK1 and ERK2), are activated in response to a variety of extracellular signals, including growth factors, hormones and, neurotransmitters. We have investigated MAP kinase signal transduction pathways in normal human osteoblastic cells. Normal human bone marrow stromal (HBMS), osteoblastic (HOB), and human (TE85, MG-63, SaOS-2), rat (ROS 17/2.8, UMR-106) and mouse (MC3T3-E1) osteoblastic cell lines contained immunodetectable p44mapk/ERK1 and p42mapk/ERK2. MAP kinase activity was measured by 'in-gel' assay using myelin basic protein as the substrate. Mainly ERK2 was rapidly activated (within 10 min) by bFGF, IGF-I and PDGF-BB in normal HOB, HBMS and human osteosarcoma cells, whereas both ERK1 and ERK2 were activated by growth factors in rat osteoblast-like cell lines, ROS 17/2.8 and UMR-106. The ERK1 activation was greater than the ERK2 in ROS 17/2.8 cells. Furthermore, ERK2 was also activated by bFGF and PDGF-BB in the mouse osteoblastic cell line, MC3T3-E1. This is the first demonstration of inter-species differences in the activation of MAP kinases in osteoblastic cells. Cyclic AMP derivatives or cAMP generating agents such as PTH and forskolin inhibited ERK2 activation by bFGF and PDGF-BB suggesting a 'cross-talk' between the two different signalling pathways activated by receptor tyrosine kinases and cAMP-dependent protein kinase. The accumulated results also suggest that the MAP kinases may be involved in mediating mitogenic and other biological actions of bFGF, IGF-I and PDGF-BB in normal human osteoblastic and bone marrow stromal cells.
authors.affiliation: Department of Internal Medicine, Washington University School of Medicine at Barnes-Jewish Hospital, St. Louis, MO 63110, USA.
authors.forename: L R
authors.initials: LR
authors.lastname: Chaudhary
authors.forename: L V
authors.initials: LV
authors.lastname: Avioli
mesh_terms: D000818:Animals; D000077214:Becaplermin; D001854:Bone Marrow Cells / Q000201:enzymology*; D017871:Calcium-Calmodulin-Dependent Protein Kinases / Q000378:metabolism*; D002478:Cells, Cultured; D005576:Colforsin / Q000378:metabolism*; D000242:Cyclic AMP / Q000378:metabolism*; D004789:Enzyme Activation; D016222:Fibroblast Growth Factor 2 / Q000378:metabolism; D006801:Humans; D007334:Insulin-Like Growth Factor I / Q000378:metabolism; D051379:Mice; D019950:Mitogen-Activated Protein Kinase 1; D048052:Mitogen-Activated Protein Kinase 3; D020928:Mitogen-Activated Protein Kinases; D010006:Osteoblasts / Q000201:enzymology*; D010446:Peptide Fragments / Q000378:metabolism*; D010982:Platelet-Derived Growth Factor / Q000378:metabolism; D020574:Proto-Oncogene Proteins c-sis; D051381:Rats; D017154:Stromal Cells / Q000201:enzymology; D019379:Teriparatide / Q000031:analogs & derivatives* / Q000378:metabolism
chemical_list: D010446:Peptide Fragments; D010982:Platelet-Derived Growth Factor; D020574:Proto-Oncogene Proteins c-sis; D016222:Fibroblast Growth Factor 2; D019379:Teriparatide; D000077214:Becaplermin; D005576:Colforsin; D007334:Insulin-Like Growth Factor I; D000242:Cyclic AMP; D017871:Calcium-Calmodulin-Dependent Protein Kinases; D019950:Mitogen-Activated Protein Kinase 1; D048052:Mitogen-Activated Protein Kinase 3; D020928:Mitogen-Activated Protein Kinases; C035748:parathyroid hormone (1-34)amide