Abstract
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.
Original language | English (US) |
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Pages (from-to) | F162-F171 |
Journal | American Journal of Physiology - Renal Physiology |
Volume | 280 |
Issue number | 1 49-1 |
DOIs | |
State | Published - Jan 2001 |
Keywords
- Fura 2
- Hypotonicity
- Inner medullary collecting duct
- Madin-Darby canine kidney
- Protein kinase C
ASJC Scopus subject areas
- Physiology
- Urology