TRPC1 protein forms only one type of native store-operated channels in HEK293 cells.
TRPC1 is a major component of store-operated calcium entry in many cell types. In our previous studies, three types of endogenous store-operated calcium channels have been described in HEK293 cells, but it remained unknown which of these channels are composed of TRPC1 proteins. Here, this issue has been addressed by performing single-channel analysis in HEK293 cells transfected with anti-TRPC1 siRNA (siTPRC1) or a TPRC1-encoding plasmid. The results show that thapsigargin-or agonist-induced calcium influx is significantly attenuated in siTRPC1-transfected HEK293 cells. TRPC1 knockdown by siRNA results in the disappearance of store-operated I(max) channels, while the properties of I(min) and I(NS) channels are unaffected. In HEK293 cells with overexpressed TRPC1 protein, the unitary current-voltage relationship of exogenous TRPC1 channels is almost linear, with a slope conductance of about 17 pS. The extrapolated reversal potential of expressed TRPC1 channels is +30 mV. Therefore, the main electrophysiological and regulatory properties of expressed TRPC1 and native I(max) channels are identical. Moreover, TRPC1 overexpression in HEK293 cells results in an increased number of store-operated I(max) channels. All these data allow us to conclude that TRPC1 protein forms native store-operated I(max) channels but is not an essential subunit for other store-operated channel types in HEK293 cells.
Institute of Cytology, Russian Academy of Sciences, Tikhoretsky Avenue 4, 194064 St. Petersburg, Russia.
Anton
A
Skopin
Alexey
A
Shalygin
Vladimir
V
Vigont
Olga
O
Zimina
Lyubov
L
Glushankova
Galina N
GN
Mozhayeva
Elena
E
Kaznacheyeva
D002118:Calcium / Q000378:metabolism*; D015870:Gene Expression; D057809:HEK293 Cells; D006801:Humans; D017136:Ion Transport / Q000187:drug effects; D008564:Membrane Potentials / Q000187:drug effects*; D018408:Patch-Clamp Techniques; D010957:Plasmids; D034741:RNA, Small Interfering / Q000235:genetics; D050052:TRPC Cation Channels / Q000819:agonists / Q000037:antagonists & inhibitors / Q000235:genetics / Q000378:metabolism*; D019284:Thapsigargin / Q000494:pharmacology; D014162:Transfection; D014544:Uridine Triphosphate / Q000494:pharmacology
D034741:RNA, Small Interfering; D050052:TRPC Cation Channels; C096351:transient receptor potential cation channel, subfamily C, member 1; D019284:Thapsigargin; D002118:Calcium; D014544:Uridine Triphosphate