TY - JOUR
T1 - Urea signaling to ERK phosphorylation in renal medullary cells requires extracellular calcium but not calcium entry
AU - Yang, Xiao Yan
AU - Zhao, Hongyu
AU - Zhang, Zheng
AU - Rodland, Karin D.
AU - Roullet, Jean Baptiste
AU - Cohen, David M.
PY - 2001/1
Y1 - 2001/1
N2 - The renal cell line mIMCD3 exhibits markedly upregulated phosphorylation of the extracellular signal-regulated kinase (ERK) 1 and 2 in response to urea treatment (200 mM for 5 min). Previous data have suggested the involvement of a classical protein kinase C (cPKC)-dependent pathway in downstream events related to urea signaling. We now show that urea-inducible ERK activation requires extracellular calcium; unexpectedly, it occurs independently of activation of cPKC isoforms. Pharmacological inhibitors of known intracellular calcium release pathways and extracellular calcium entry pathways fail to inhibit ERK activation by urea. Fura 2 ratiometry was used to assess the effect of urea treatment on intracellular calcium mobilization. In single-cell analyses using subconfluent monolayers and in population-wide analyses using both confluent monolayers and cells in suspension, urea failed to increase intracellular calcium concentration. Taken together, these data indicate that urea-inducible ERK activation requires calcium action but not calcium entry. Although direct evidence is lacking, one possible explanation could include involvement of a calcium-dependent extracellular moiety of a cell surface-associated protein.
AB - The renal cell line mIMCD3 exhibits markedly upregulated phosphorylation of the extracellular signal-regulated kinase (ERK) 1 and 2 in response to urea treatment (200 mM for 5 min). Previous data have suggested the involvement of a classical protein kinase C (cPKC)-dependent pathway in downstream events related to urea signaling. We now show that urea-inducible ERK activation requires extracellular calcium; unexpectedly, it occurs independently of activation of cPKC isoforms. Pharmacological inhibitors of known intracellular calcium release pathways and extracellular calcium entry pathways fail to inhibit ERK activation by urea. Fura 2 ratiometry was used to assess the effect of urea treatment on intracellular calcium mobilization. In single-cell analyses using subconfluent monolayers and in population-wide analyses using both confluent monolayers and cells in suspension, urea failed to increase intracellular calcium concentration. Taken together, these data indicate that urea-inducible ERK activation requires calcium action but not calcium entry. Although direct evidence is lacking, one possible explanation could include involvement of a calcium-dependent extracellular moiety of a cell surface-associated protein.
KW - Fura 2
KW - Hypotonicity
KW - Inner medullary collecting duct
KW - Madin-Darby canine kidney
KW - Protein kinase C
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U2 - 10.1152/ajprenal.2001.280.1.f162
DO - 10.1152/ajprenal.2001.280.1.f162
M3 - Article
C2 - 11133526
AN - SCOPUS:0035009188
VL - 280
SP - F162-F171
JO - American journal of physiology. Renal physiology
JF - American journal of physiology. Renal physiology
SN - 0363-6127
IS - 1 49-1
ER -