TY - JOUR
T1 - Interaction between TRPC1/TRPC4 assembly and STIM1 contributes to store-operated Ca2+ entry in mesangial cells
AU - Sours-Brothers, Sherry
AU - Ding, Min
AU - Graham, Sarabeth
AU - Ma, Rong
N1 - Funding Information:
This study was supported by Young Investigator Grant from National Kidney Foundation (Ma) and Research Award from American Diabetes Association (Ma).
PY - 2009/6
Y1 - 2009/6
N2 - Although Orai1 protein was recently identified as the component of CRAC channels in hematopoietic cells, store-operated channels (SOC) in other cell types may have a different molecular entity. Also, the activation mechanism of SOC remains unclear, in general. In the present study, we tested the hypothesis that TRPC1 and TRPC4 proteins were functional subunits of SOC in glomerular mesangial cells (MCs) and that STIM1 was required for the channel activation through interaction with the TRPC proteins. In cultured human MCs, cell-attached patch clamp and fura-2 fluorescence measurements showed that single knockdown of either TRPC1 or TRPC4 significantly attenuated thapsigargin-induced membrane currents and Ca2+ entry as well as Ang II-induced channel activity. Double knockdown of both TRPCs resulted in a comparable inhibition on store-operated Ca2+ entry with single knockdown of either TRPC. Consistent with our previous report, coimmunoprecipitation showed a physical interaction between TRPC1 and TRPC4. Furthermore, we found that knockdown of STIM1 using RNAi significantly reduced the thapsigargin-stimulated membrane currents. Co-immunoprecipitation showed that STIM1 interacted with TRPC4, but not TRPC1. In addition, simultaneous inhibition of STIM1 and TRPC1 resulted in a comparable effect on SOC with single inhibition of either one of them. Taken together, we conclude that in glomerular mesangial cells, the TRPC1/TRPC4 complexes constitute the functional subunits of SOC and that the interaction between STIM1 and TRPC4 may be the mechanism for the activation of the channels.
AB - Although Orai1 protein was recently identified as the component of CRAC channels in hematopoietic cells, store-operated channels (SOC) in other cell types may have a different molecular entity. Also, the activation mechanism of SOC remains unclear, in general. In the present study, we tested the hypothesis that TRPC1 and TRPC4 proteins were functional subunits of SOC in glomerular mesangial cells (MCs) and that STIM1 was required for the channel activation through interaction with the TRPC proteins. In cultured human MCs, cell-attached patch clamp and fura-2 fluorescence measurements showed that single knockdown of either TRPC1 or TRPC4 significantly attenuated thapsigargin-induced membrane currents and Ca2+ entry as well as Ang II-induced channel activity. Double knockdown of both TRPCs resulted in a comparable inhibition on store-operated Ca2+ entry with single knockdown of either TRPC. Consistent with our previous report, coimmunoprecipitation showed a physical interaction between TRPC1 and TRPC4. Furthermore, we found that knockdown of STIM1 using RNAi significantly reduced the thapsigargin-stimulated membrane currents. Co-immunoprecipitation showed that STIM1 interacted with TRPC4, but not TRPC1. In addition, simultaneous inhibition of STIM1 and TRPC1 resulted in a comparable effect on SOC with single inhibition of either one of them. Taken together, we conclude that in glomerular mesangial cells, the TRPC1/TRPC4 complexes constitute the functional subunits of SOC and that the interaction between STIM1 and TRPC4 may be the mechanism for the activation of the channels.
KW - Glomerular mesangial cell
KW - STIM1
KW - Store-operated Ca channel
KW - Store-operated Ca entry
KW - TRPC1
KW - TRPC4
UR - http://www.scopus.com/inward/record.url?scp=66449120243&partnerID=8YFLogxK
U2 - 10.3181/0809-RM-279
DO - 10.3181/0809-RM-279
M3 - Article
C2 - 19307462
AN - SCOPUS:66449120243
SN - 1535-3702
VL - 234
SP - 673
EP - 682
JO - Experimental Biology and Medicine
JF - Experimental Biology and Medicine
IS - 6
ER -