TRPC 6 regulates cell cycle progression by modulating membrane potential in bone marrow stromal cells

Background and Purpose Ca 2+ influx is important for cell cycle progression, but the mechanisms involved seem to vary. We investigated the potential roles of transient receptor potential (TRP) channels and store‐operated Ca 2+ entry ( SOCE )‐related molecules STIM (stromal interaction molecule)/ O rai in the cell cycle progression of rat bone marrow stromal cells ( BMSC s), a reliable therapeutic resource for regenerative medicine. Experimental Approach PCR and immunoblot analyses were used to examine m RNA and protein levels, fluorescence imaging and patch clamping for Ca 2+ influx and membrane potential measurements, and flow cytometry for cell cycle analysis. Key Results Cell cycle synchronization of BMSC s revealed S phase‐specific enhancement of TRPC 1, STIM and Orai m RNA and protein expression. In contrast, TRPC 6 expression decreased in the S phase and increased in the G 1 phase. Resting membrane potential ( RMP ) of BMSC s was most negative and positive in the S and G 1 phases, respectively, and was accompanied by an enhancement and attenuation of SOCE respectively. Chemically depolarizing/hyperpolarizing the membrane erased these differences in SOCE magnitude during the cell cycle. siRNA knockdown of TRPC 6 produced a negative shift in RMP , increased SOCE and caused redistribution of BMSC s with increased populations in the S and G 2 / M phases and accumulation of cyclins A 2 and B 1. A low concentration of G d 3+ (1 μ M ) suppressed BMSC proliferation at its concentration to inhibit SOC channels relatively specifically. Conclusions and Implications TRPC 6, by changing the membrane potential, plays a pivotal role in controlling the SOCE magnitude, which is critical for cell cycle progression of BMSC s. This finding provides a new therapeutic strategy for regulating BMSC proliferation.