TRPC3-mediated Ca(2+) entry contributes to mouse airway smooth muscle cell proliferation induced by lipopolysaccharide.

Airway remodeling is a histopathological hallmark of chronic respiratory diseases that includes airway smooth muscle cell (ASMC) proliferation. Canonical transient receptor potential channel-3 (TRPC3)-encoded nonselective cation channels (NSCCs) are important native constitutively active channels that play significant roles in physiological and pathological conditions in ASMCs. Lipopolysaccharides (LPSs), known as lipoglycans and endotoxin, have been proven to be inducers of airway remodeling, though the mechanisms remain unclear. We hypothesized that TRPC3 is important in LPS-induced airway remodeling by regulating ASMC proliferation. To test this hypothesis, mouse ASMCs were cultured with or without LPS for 48h. Cell viability, TRPC3 protein expression, NSCC currents and changes in intracellular calcium concentration ([Ca(2+)]i) were then analyzed using an MTT assay, western blotting, whole-cell patch clamp and calcium imaging, respectively. The results showed that LPS treatment significantly induced ASMC proliferation, up-regulation of TRPC3 protein expression and enhancement of NSCC currents, resting [Ca(2+)]i and ACh-elicited changes in [Ca(2+)]i. TRPC3 blocker Gd(3+), TRPC3 blocking antibody or TRPC3 gene silencing by siRNA significantly inhibited LPS-induced up-regulation of TRPC3 protein, enhancement of NSCC currents, resting [Ca(2+)]i and ACh-elicited changes in [Ca(2+)]i, eventually inhibiting LPS-induced ASMCproliferation. These results demonstrated that TRPC3-mediated Ca(2+) entry contributed to LPS-induced ASMC proliferation and identified TRPC3 as a possible key target in airway remodeling intervention.

Chen XX ，Zhang JH ，Pan BH ，Ren HL ，Feng XL ，Wang JL ，Xiao JH ... -  《-》

Role of canonical transient receptor potential channel-3 in acetylcholine-induced mouse airway smooth muscle cell proliferation.

Canonical transient receptor potential channel-3 (TRPC3)-encoded Ca2+-permeable nonselective cation channel (NSCC) has been proven to be an important native constitutively active channel in airway smooth muscle cell (ASMC), which plays significant roles in physiological and pathological conditions by controlling Ca2+ homeostasis in ASMC. Acetylcholine (ACh) is generally accepted as a contractile parasympathetic neurotransmitter in the airway. Recently studies have revealed the pathological role of ACh in airway remodeling, however, the mechanisms remain unclear. Here, we investigated the role of TRPC3 in ACh-induced ASMC proliferation. Primary mouse ASMCs were cultured with or without ACh treatment, then cell viability, TRPC3 expression, NSCC currents and [Ca2+]i changes were examined by MTT assay, cell counting, Western blotting, standard whole-cell patch clamp recording and calcium imaging, respectively. Small interfering RNA (siRNA) technology was used to confirm the contribution of TRPC3 to ACh-induced ASMC proliferation. TRPC3 blocker Gd3+, antibody or siRNA largely inhibited ACh-induced up-regulation of TRPC3 protein, enhancement of NSCC currents, resting [Ca2+]i and KCl-induced changes in [Ca2+]i, eventually inhibiting ACh-induced ASMC proliferation. Our data suggested ACh could induce ASMC proliferation, and TRPC3 may be involved in ACh-induced ASMC proliferation that occurs with airway remodeling.

Chen XX ，Zhang JH ，Pan BH ，Ren HL ，Feng XL ，Wang JL ，Xiao JH ... -  《-》

Inositol 1,4,5-trisphosphate activates TRPC3 channels to cause extracellular Ca2+ influx in airway smooth muscle cells.

Transient receptor potential-3 (TRPC3) channels play a predominant role in forming nonselective cation channels (NSCCs) in airway smooth muscle cells (ASMCs) and are significantly increased in their activity and expression in asthmatic ASMCs. To extend these novel findings, we have explored the regulatory mechanisms that control the activity of TRPC3 channels. Our data for the first time reveal that inositol 1,4,5-trisphosphate (IP3), an important endogenous signaling molecule, can significantly enhance the activity of single NSCCs in ASMCs. The analog of diacylglycerol (DAG; another endogenous signaling molecule), 1-oleyl-2-acetyl-sn-glycerol (OAG), 1-stearoyl-2-arachidonoyl-sn-glycerol (SAG), and 1-stearoyl-2-linoleoyl-sn-glycerol (SLG) all augment NSCC activity. The effects of IP3 and OAG are fully abolished by lentiviral short-hairpin (sh)RNA-mediated TRPC3 channel knockdown (KD). The stimulatory effect of IP3 is eliminated by heparin, an IP3 receptor (IP3R) antagonist that blocks the IP3-binding site, but not by xestospongin C, the IP3R antagonist that has no effect on the IP3-binding site. Lentiviral shRNA-mediated KD of IP3R1, IP3R2, or IP3R3 does not alter the excitatory effect of IP3. TRPC3 channel KD greatly inhibits IP3-induced increase in intracellular Ca(2+) concentration. IP3R1 KD produces a similar inhibitory effect. TRPC3 channel and IP3R1 KD both diminish the muscarinic receptor agonist methacholine-evoked Ca(2+) responses. Taking these findings together, we conclude that IP3, the important intracellular second messenger, may activate TRPC3 channels to cause extracellular Ca(2+) influx, in addition to opening IP3Rs to induce intracellular Ca(2+) release. This novel extracellular Ca(2+) entry route may play a significant role in mediating IP3-mediated numerous cellular responses in ASMCs and other cells.

Song T ，Hao Q ，Zheng YM ，Liu QH ，Wang YX ... -  《-》

The effects of transient receptor potential channel (TRPC) on airway smooth muscle cell isolated from asthma model mice.

This study aimed to validate whether transient receptor potential channel1 (TRPC1) and TRPC3 participate in the regulation the proliferation of airway smooth muscle cells (ASMCs) through modulating calcium ion (Ca2+ ) influx in vitro. Chronic model of murine asthma was induced and ASMCs isolated from asthmatic mice were used in this whole study. TRPC1 and TRPC3 were upregulated in asthmatic mouse ASMCs and selected for further investigation. Ca2+ concentration and the cell viability of asthmatic mouse ASMCs were significantly higher than that from non- asthma mice, however, TRPC channels blocker SKF96365 alleviated these effects. Furthermore, TRPC1 or TRPC3 overexpression markedly increased Ca2+ concentration and significantly induced the viability of ASMCs; whereas TRPC1 or TRPC3 knockdown exerted the completely conversed effects. Moreover, knockdown of TRPC1 and TRPC3 also exerted different effects on the protein expression of growth-related proteins p-p38, p-JNK, cleaved caspase-3 and Bcl-2, as well as on cell cycle. Finally, we found Ca2+ chelator EGTA or BAPTA-AM significantly diminished the effects of si-TRPC1 and si-TRPC3 on the cell viability, cell cycle, and the protein expression of p-p38, p-JNK, cleaved caspase-3, and Bcl-2 in asthmatic mouse ASMCs. Our findings demonstrated that the effects of TRPC1 and TRPC3 on the cell viability and cell cycle of ASMCs were, at least partially, through regulating Ca2+ influx.

Zhang X ，Zhao Z ，Ma L ，Guo Y ，Li X ，Zhao L ，Tian C ，Tang X ，Cheng D ，Chen Z ，Zhang L ... -  《-》

Functional role of canonical transient receptor potential 1 and canonical transient receptor potential 3 in normal and asthmatic airway smooth muscle cells.

Xiao JH ，Zheng YM ，Liao B ，Wang YX ... -  《-》