title: CaT1 contributes to the stores-operated calcium current in Jurkat T-lymphocytes.
abstract: T-lymphocyte activation requires sustained Ca(2+) signaling dependent upon capacitative Ca(2+) entry (CCE). The protein(s) that forms the stores-operated Ca(2+) channel (SOCC) responsible for CCE has long been sought but has not been definitively identified. Members of the TRPV family (transient receptor potential superfamily-vanilloid receptor subfamily) of channel genes have been proposed to encode SOCCs responsible for CCE in non-excitable cells. Here we present evidence that a member of the TRPV group, CaT1, is involved in generating I(CRAC), the CCE current that is necessary for T-cell activation. CaT1 is expressed in Jurkat T-lymphocytes. When overexpressed in Jurkat cells, CaT1 produces a Ca(2+) entry current that mimics the endogenous I(CRAC) in its dependence on external Ca(2+), inactivation by elevated concentration of internal Ca(2+), and pharmacological block by capsaicin. Overexpressed CaT1 is partially regulated by the release of internal Ca(2+) stores via thapsigargin or receptor-mediated generation of inositol 1,4,5-trisphosphate. A pore-region mutant of CaT1, TRIA-CaT1, fails to carry Ca(2+) currents and associates with co-expressed wild type CaT1 to functionally suppress permeation of Ca(2+) ions. Expression of the TRIA-CaT1 mutant in Jurkat cells results in suppression of the endogenous I(CRAC). Taken together these results indicate that CaT1 is the channel protein that contributes to T-lymphocyte SOCCs either alone or as a subunit in a heterogeneous channel complex.
mesh_terms: D000818:Animals; D016466:CHO Cells; D002118:Calcium / Q000378:metabolism*; D015220:Calcium Channels / Q000235:genetics / Q000378:metabolism* / Q000502:physiology; D002211:Capsaicin / Q000494:pharmacology; D003001:Cloning, Molecular; D006224:Cricetinae; D018076:DNA, Complementary / Q000378:metabolism; D005799:Genes, Dominant; D006801:Humans; D015151:Immunoblotting; D015544:Inositol 1,4,5-Trisphosphate / Q000378:metabolism; D019169:Jurkat Cells; D008856:Microscopy, Fluorescence; D009154:Mutation; D020133:Reverse Transcriptase Polymerase Chain Reaction; D050916:TRPV Cation Channels; D013997:Time Factors; D014162:Transfection
chemical_list: D015220:Calcium Channels; D018076:DNA, Complementary; D050916:TRPV Cation Channels; C120776:TRPV6 channel; D015544:Inositol 1,4,5-Trisphosphate; D002211:Capsaicin; D002118:Calcium