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Role of TRPC3 channels in ATP‐induced Ca 2+ signaling in principal cells of the inner medullary collecting duct
Author(s) -
Goel Monu,
Schilling William
Publication year - 2010
Publication title -
the faseb journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.709
H-Index - 277
eISSN - 1530-6860
pISSN - 0892-6638
DOI - 10.1096/fasebj.24.1_supplement.606.14
Subject(s) - trpc3 , apical membrane , thapsigargin , chemistry , microbiology and biotechnology , epithelial polarity , forskolin , biophysics , endoplasmic reticulum , biochemistry , biology , receptor , cell , membrane , transient receptor potential channel , trpc
TRPC3 channels are expressed in the apical membrane of principal cells of the collecting duct (CD) both in vivo and in cultured mouse IMCD‐3 cells. Studies have shown that ATP‐induced apical‐to‐basolateral transepithelial Ca 2+ flux across IMCD‐3 monolayers is increased by over‐expression of TRPC3 and attenuated by a dominant‐negative TRPC3 construct (dn‐TRPC3). To test the hypothesis that Ca 2+ entry occurs via TRPC3 channels, Ca 2+ permeability of the apical membrane of fura‐2‐loaded IMCD‐3 cells was estimated by the Mn 2+ quench technique. Mn 2+ influx across the apical membrane was increased 12‐ to 16‐fold by apical ATP, and was blocked by BTP2, an inhibitor of TRPC3 channels with an IC 50 of <100 nM. In contrast, Mn 2+ influx was increased only ~2‐fold by basolateral ATP. Mn 2+ influx was also activated by the diacyl‐glycerol analog, SAG. Apical ATP‐ and SAG‐induced Mn 2+ influx was increased by over‐expression of TRPC3 and completely blocked by expression of the dn‐TRPC3 construct. Mn 2+ influx was also stimulated ~2‐fold by thapsigargin applied to either the apical or basolateral side, but thapsigargin‐induced flux was unaffected by over‐expression of TRPC3 or dn‐TRPC3. These results demonstrate that stimulation of apical purinergic receptors activates Ca 2+ influx across the apical membrane of IMCD‐3 cells via TRPC3 channels by a mechanism that is independent of Ca 2+ store depletion. Supported in part by HL097355.