TRPC channels mediated calcium entry is required for proliferation of human airway smooth muscle cells induced by nicotine-nAChR.

The present study was designed to explore the role of transient receptor potential canonical 3 (TRPC3) in nicotine-induced chronic obstructive pulmonary disease (COPD) and its underlying mechanism. In this study, the expression and localization of α5 nicotinic acetylcholine receptor (α5-nAchR) in lung tissues were determined by western blotting and immunohistochemistry. The quantitative real-time PCR (qRT-PCR) analysis was performed to examine the mRNA expression levels of α5-nAchR and TRPC3 in human airway smooth muscle cells (HASMCs). Cell viability was assessed by CCK-8 assay. Proliferation was detected by cell counting and EdU immunofluorescent staining. Fluorescence calcium imaging was carried out to measure cytosolic Ca²⁺ ([Ca²⁺]cyt) concentration. The results showed that the α5-nAchR and TRPC3 expressions were significantly up-regulated in lung tissues of COPD smokers. Nicotine promoted HASMC proliferation, which was accompanied by elevated α5-nAchR and TRPC3 expressions, basal [Ca²⁺]cyt, store-operated calcium entry (SOCE) and the rate of Mn²⁺ quenching in HASMCs. Further investigation indicated that nicotine-induced Ca²⁺ response and TRPC3 up-regulation was reversibly blocked by small interfering RNA (siRNA) suppression of α5-nAChR. The knockdown of TRPC3 blunted Ca²⁺ response and HASMC proliferation induced by nicotine. In conclusion, nicotine-induced HASMC proliferation was mediated by TRPC3-dependent calcium entry via α5-nAchR, which provided a potential target for treatment of COPD.

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