There is no author summary for this article yet. Authors can add summaries to their articles on ScienceOpen to make them more accessible to a non-specialist audience.
Abstract
TRPC2 is a member of the transient receptor potential (TRP) superfamily of Ca2+-permeable
channels expressed in nonexcitable cells. TRPC2 is involved in a number of physiological
processes including sensory activation of the vomeronasal organ, sustained Ca2+ entry
in sperm, and regulation of calcium influx by erythropoietin. Here, a new splice variant
of TRPC2, called "Similar to mouse TRPC2" (smTRPC2), was identified consisting of
213 amino acids, largely coincident with the N-terminus of TRPC2 clone 17. This splice
variant lacks all six TRPC2 transmembrane domains and the calcium pore. Expression
of smTRPC2 was found in all tissues examined by RT-PCR and in primary erythroid cells
by RT-PCR and Western blotting. Confocal microscopy of CHO-S cells transfected with
TRPC2 clone 14 and smTRPC2 demonstrated that TRPC2 clone 14 and smTRPC2 both localize
at or near the plasma membrane and in the perinuclear region. Cell surface localization
of TRPC2 was confirmed with biotinylation, and was not substantially affected by smTRPC2
expression. Coassociation of TRPC2 c14 and alpha with smTRPC2 was confirmed by immunoprecipitation.
To examine the functional significance of smTRPC2 expression, a CHO-S model was used
to study its effect on calcium influx stimulated by Epo through TRPC2. Single CHO-S
cells which express transfected Epo-R were identified by detection of green fluorescent
protein (GFP). Cells that express transfected TRPC2 c14 or alpha were identified by
detection of blue fluorescent protein (BFP). [Ca]i was quantitiated with Fura Red
fluorescence using digital video imaging. Epo stimulated calcium influx through TRPC2
isoforms c14 and alpha, which was inhibited by coexpression of smTRPC2. These data
demonstrate that a short splice variant of TRPC2 exists in many cell types, which
associates with and modifies the activity of functional TRPC2 splice variants.