Mammalian homologues of the Drosophila canonical Transient
Receptor Potential (TRPC) protein have been proposed to encode the
store-operated Ca2+ influx (SOC) channel(s). This study
examines the role of TRPC1 in the SOC mechanism of retinal cells.
htrpc1 transcript was detected in bovine retinal and in human
adult retinal pigment epithelial (ARPE) cells. Western blot analysis also
confirmed the expression of TRPC1 protein in neuronal cells including
retina and ARPE cells. To determine the role of TRPC1 protein in retinal
cells, TRPC1 was recombinantly expressed in ARPE cells and changes in
intracellular Ca2+ were analyzed. ARPE cells stably transfected
with htrp1 cDNA displayed 2-fold higher Ca2+ influx
with no significant increase in the basal influx. Consistent with this the
overexpressed TRPC1 protein was localized in the plasma membrane region of
ARPE cells. Interestingly, both bovine retinal tissues and ARPE cells
showed that TRPC1 protein co-localizes and could be co-immunoprecipitated
with β-tubulin. Disruption of tubulin by colchicine significantly
decreased both plasma membrane staining of the TRPC1 protein and
Ca2+ influx in ARPE cells. These results suggest that TRPC1
channel protein is expressed in retinal cells, further,
targeting/retention of the TRPC1 protein to the plasma membrane in
retinal cells is mediated via its interaction with
β-tubulin.