TY - JOUR
T1 - Calcium-sensing Receptor-mediated ERK1/2 Activation Requires Gα i2 Coupling and Dynamin-independent Receptor Internalization
AU - Holstein, Deborah M.
AU - Berg, Kelly A.
AU - Leeb-Lundberg, L. M.Fredrik
AU - Olson, Merle S.
AU - Saunders, Christine
PY - 2004/3/12
Y1 - 2004/3/12
N2 - The calcium-sensing receptor (CaR) recently has been shown to activate MAP kinase (ERK1/2) in various cell types as well as in heterologous expression systems. In this study we show that the CaR agonist NPS R-467 (1 μM), which does not activate the CaR by itself, robustly activates ERK1/2 in the presence of a low concentration of Ca2+ (0.5 mM CaCl2) in human embryonic kidney (HEK) cells permanently expressing the human CaR (HEK-hCaR). Ca2+ (4 mM) also activates ERK1/2 but with differing kinetics. CaR-dependent ERK1/2 activation begins to desensitize to 4 mM Ca2+ after 10 min, whereas there is no desensitization to NPS R-467/CaCl2, as late as 4 h. Moreover, recovery from desensitization occurs as rapidly as 30 min with 4 mM CaCl2. Pretreatment of HEK-hCaR cells with concanavalin A (250 μg/ml) to block CaR internalization completely eliminated the NPS R-467/CaCl2-mediated ERK1/2 activation but did not block the 2-min time point of 4 mM Ca2+-mediated ERK1/2 activation. Neither dominant-negative dynamin (K44A) nor dominant-negative β-arrestin inhibited ERK1/2 activation by either CaR agonist treatment, suggesting that CaR-elicited ERK1/2 signaling occurs via a dynamin-independent pathway. Pertussis toxin pretreatment partially attenuated the 4 mM Ca 2+-ERK1/2 activation; this attenuated activity was completely restored by co-expression of the Gαi2C351I but not Gαi1C351I or Gαi3C351I G proteins, PTX-insensitive G protein mutants. Taken together, these data suggest that both 4 mM Ca2+ and NPS R-467/CaCl2 activate ERK1/2 via distinguishable pathways in HEK-hCaR cells and may represent a nexus to differentially regulate differentiation versus proliferation via CaR activation.
AB - The calcium-sensing receptor (CaR) recently has been shown to activate MAP kinase (ERK1/2) in various cell types as well as in heterologous expression systems. In this study we show that the CaR agonist NPS R-467 (1 μM), which does not activate the CaR by itself, robustly activates ERK1/2 in the presence of a low concentration of Ca2+ (0.5 mM CaCl2) in human embryonic kidney (HEK) cells permanently expressing the human CaR (HEK-hCaR). Ca2+ (4 mM) also activates ERK1/2 but with differing kinetics. CaR-dependent ERK1/2 activation begins to desensitize to 4 mM Ca2+ after 10 min, whereas there is no desensitization to NPS R-467/CaCl2, as late as 4 h. Moreover, recovery from desensitization occurs as rapidly as 30 min with 4 mM CaCl2. Pretreatment of HEK-hCaR cells with concanavalin A (250 μg/ml) to block CaR internalization completely eliminated the NPS R-467/CaCl2-mediated ERK1/2 activation but did not block the 2-min time point of 4 mM Ca2+-mediated ERK1/2 activation. Neither dominant-negative dynamin (K44A) nor dominant-negative β-arrestin inhibited ERK1/2 activation by either CaR agonist treatment, suggesting that CaR-elicited ERK1/2 signaling occurs via a dynamin-independent pathway. Pertussis toxin pretreatment partially attenuated the 4 mM Ca 2+-ERK1/2 activation; this attenuated activity was completely restored by co-expression of the Gαi2C351I but not Gαi1C351I or Gαi3C351I G proteins, PTX-insensitive G protein mutants. Taken together, these data suggest that both 4 mM Ca2+ and NPS R-467/CaCl2 activate ERK1/2 via distinguishable pathways in HEK-hCaR cells and may represent a nexus to differentially regulate differentiation versus proliferation via CaR activation.
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U2 - 10.1074/jbc.M312039200
DO - 10.1074/jbc.M312039200
M3 - Article
C2 - 14701866
AN - SCOPUS:1642264730
SN - 0021-9258
VL - 279
SP - 10060
EP - 10069
JO - Journal of Biological Chemistry
JF - Journal of Biological Chemistry
IS - 11
ER -