Abstract
TRPC proteins have been described as non-selective cation channels and are thought to be involved in the regulation of Ca2+ movement in various cells, including airway smooth muscle (ASM) cells. In order to study the role of these channels in ASM cells, transfection of a small interfering RNA (siRNA) designed against the TRPC6 channel was performed in guinea pig primary ASM cells. This specific siRNA was complexed with the new X-TremeGene (X-TG) chemical transfection reagent, whose efficiency and low cytotoxicity were determined by the use of a non-silencing rhodamine-tagged siRNA. It was found that more than 95% of cells were transfected by an optimized protocol. Verification of TRPC6 transcript down-regulation was determined by RT-PCR while Western blot analysis attested to lower protein content in the microsomal fraction. Micro-spectrofluorimetry measurements of control and siRNA-treated cells revealed that lower TRPC6 expression did not affect OAG-induced intracellular Ca2+ movement. Thus, TRPC6 channels cannot be defined as simple Ca2+ transporters but more likely as protein complexes supporting monovalent cation conductance in ASM cells. These conductances would in turn facilitate membrane depolarization of high input resistance cells, Ca2+ channel activation and tone increase. In conclusion, this study defines a valuable model of RNA interference study in primary cultures of ASM cells, eventually allowing for silencing of other target proteins for which no pharmacological modulators are currently available.
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Acknowledgments
The authors wish to thank Claude Roberge for constructive comments and Pierre Pothier for the critical reading of the manuscript. This work was supported by a CIHR grant MOP-57677 to ER. Dr Rousseau is a member of the Health Respiratory Network of the FRSQ: http://www.rsr.chus.qc.ca
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Godin, N., Rousseau, E. TRPC6 silencing in primary airway smooth muscle cells inhibits protein expression without affecting OAG-induced calcium entry. Mol Cell Biochem 296, 193–201 (2007). https://doi.org/10.1007/s11010-006-9309-1
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DOI: https://doi.org/10.1007/s11010-006-9309-1