Regulation of MAP kinase by calcium-sensing receptor in bovine parathyroid and CaR-transfected HEK293 cells.
Regulation of the extracellular signal-regulated kinase 1 and 2 (ERK1/2) pathway by the extracellular calcium (Ca2+o)-sensing receptor (CaR) was investigated in bovine parathyroid and CaR-transfected human embryonic kidney (HEKCaR) cells. Elevating Ca2+o or adding the selective CaR activator NPS R-467 elicited rapid, dose-dependent phosphorylation of ERK1/2. These phosphorylations were attenuated by pretreatment with pertussis toxin (PTX) or by treatment with the phosphotyrosine kinase (PTK) inhibitors genistein and herbimycin, the phosphatidylinositol-specific phospholipase C (PI-PLC) inhibitor U-73122, or the protein kinase C (PKC) inhibitor GF109203X and were enhanced by the PKC activator phorbol 12-myristate 13-acetate. Combined treatment with PTX and inhibitors of both PKC and PTK nearly abolished high Ca2+o-evoked ERK1/2 activation in HEKCaR cells, demonstrating CaR-mediated coupling via both Gq and G(i). High Ca2+o increased serine phosphorylation of the 85-kDa cytosolic phospholipase A2 (cPLA2) in both parathyroid and HEKCaR cells. The selective mitogen-activated protein kinase (MAPK) inhibitor PD98059 abolished high-Ca2+o)-induced ERK1/2 activation and reduced cPLA2 phosphorylation in both cell types, documenting MAPK's role in cPLA2 activation. Thus our data suggest that the CaR activates MAPK through PKC, presumably through Gq/11-mediated activation of PI-PLC, as well as through G(i)- and PTK-dependent pathway(s) in bovine parathyroid and HEKCaR cells and indicate the importance of MAPK in cPLA2 activation.
Kifor
O
O
Endocrine-Hypertension Division and Membrane Biology Program, Department of Medicine, Brigham and Women's Hospital, Boston, Massachusetts 02115, USA.
MacLeod
R J
RJ
Diaz
R
R
Bai
M
M
Yamaguchi
T
T
Yao
T
T
Kifor
I
I
Brown
E M
EM
D000818:Animals; D002118:Calcium / Q000378:metabolism* / Q000494:pharmacology; D002417:Cattle; D004791:Enzyme Inhibitors / Q000494:pharmacology; D006801:Humans; D007668:Kidney / Q000166:cytology / Q000187:drug effects / Q000378:metabolism*; D020935:MAP Kinase Signaling System / Q000187:drug effects / Q000502:physiology*; D019950:Mitogen-Activated Protein Kinase 1 / Q000187:drug effects / Q000378:metabolism*; D048052:Mitogen-Activated Protein Kinase 3; D020928:Mitogen-Activated Protein Kinases / Q000187:drug effects / Q000378:metabolism*; D010280:Parathyroid Glands / Q000166:cytology / Q000187:drug effects / Q000378:metabolism*; D037342:Pertussis Toxin; D010741:Phospholipases A / Q000187:drug effects / Q000378:metabolism; D054467:Phospholipases A2; D010766:Phosphorylation; D044169:Receptors, Calcium-Sensing; D011956:Receptors, Cell Surface / Q000187:drug effects / Q000378:metabolism*; D010566:Virulence Factors, Bordetella / Q000494:pharmacology
D004791:Enzyme Inhibitors; D044169:Receptors, Calcium-Sensing; D011956:Receptors, Cell Surface; D010566:Virulence Factors, Bordetella; D037342:Pertussis Toxin; D019950:Mitogen-Activated Protein Kinase 1; D048052:Mitogen-Activated Protein Kinase 3; D020928:Mitogen-Activated Protein Kinases; D010741:Phospholipases A; D054467:Phospholipases A2; D002118:Calcium