Role of capacitative Ca2+ entry in bronchial contraction and remodeling

2002 ◽  
Vol 92 (4) ◽  
pp. 1594-1602 ◽  
Author(s):  
Michele Sweeney ◽  
Sharon S. McDaniel ◽  
Oleksandr Platoshyn ◽  
Shen Zhang ◽  
Ying Yu ◽  
...  
Keyword(s):  
Smooth Muscle ◽  
Transient Receptor Potential ◽  
Bronchial Hyperresponsiveness ◽  
Receptor Potential ◽  
Transient Receptor Potential Channel ◽  
Wall Thickening ◽  
Bronchial Wall ◽  
Intracellular Ca ◽  
Transient Receptor

Asthma is characterized by airway inflammation, bronchial hyperresponsiveness, and airway obstruction by bronchospasm and bronchial wall thickening due to smooth muscle hypertrophy. A rise in cytosolic free Ca2+ concentration ([Ca2+]cyt) may serve as a shared signal transduction element that causes bronchial constriction and bronchial wall thickening in asthma. In this study, we examined whether capacitative Ca2+ entry (CCE) induced by depletion of intracellular Ca2+ stores was involved in agonist-mediated bronchial constriction and bronchial smooth muscle cell (BSMC) proliferation. In isolated bronchial rings, acetylcholine (ACh) induced a transient contraction in the absence of extracellular Ca2+ because of Ca2+ release from intracellular Ca2+ stores. Restoration of extracellular Ca2+in the presence of atropine, an M-receptor blocker, induced a further contraction that was apparently caused by a rise in [Ca2+]cyt due to CCE. In single BSMC, amplitudes of the store depletion-activated currents ( I SOC) and CCE were both enhanced when the cells proliferate, whereas chelation of extracellular Ca2+ with EGTA significantly inhibited the cell growth in the presence of serum. Furthermore, the mRNA expression of TRPC1, a transient receptor potential channel gene, was much greater in proliferating BSMC than in growth-arrested cells. Blockade of the store-operated Ca2+channels by Ni2+ decreased I SOC and CCE and markedly attenuated BSMC proliferation. These results suggest that upregulated TRPC1 expression, increased I SOC, enhanced CCE, and elevated [Ca2+]cyt may play important roles in mediating bronchial constriction and BSMC proliferation.

Enhanced capacitative calcium entry and TRPC channel gene expression in human LES smooth muscle

2003 ◽  
Vol 284 (6) ◽  
pp. G1074-G1083 ◽  
Author(s):  
Jian Wang ◽  
Lisanne G. Laurier ◽  
Stephen M. Sims ◽  
Harold G. Preiksaitis
Keyword(s):  
Gene Expression ◽  
Smooth Muscle ◽  
Transient Receptor Potential ◽  
Smooth Muscles ◽  
Receptor Potential ◽  
Transient Receptor Potential Channel ◽  
Transcriptional Expression ◽  
External Application ◽  
Intracellular Ca ◽  
Transient Receptor

Transient receptor potential channel ( TRPC) genes encode Ca2+-permeable channels mediating capacitative Ca2+ entry (CCE), which maintains intracellular Ca2+ stores. We compared TRPC gene expression and CCE in human esophageal body (EB) and lower esophageal sphincter (LES), because these smooth muscles have distinct contractile functions that are likely associated with different Ca2+ regulatory mechanisms. Circular layer smooth muscle cells were grown in primary culture. Transcriptional expression of TRPC genes was compared by semiquantitative RT-PCR. CCE was measured by fura 2 Ca2+ fluorescence after blockade of sarcoplasmic reticulum Ca2+-ATPase with thapsigargin. mRNA for TRPC1, TRPC3, TRPC4, TRPC5, and TRPC6was identified in EB and LES. TRPC3 and TRPC4were more abundant in LES than EB. Basal concentration of free intracellular Ca2+ ([Ca2+]i) was similar in cells from LES (138 ± 8 nmol/l) and EB (110 ± 6 nmol/l) and increased with ACh (10 μmol/l; 650 ± 28 and 590 ± 21 nmol/l, respectively). With zero Ca2+ in bath, thapsigargin (2 μmol/l) increased [Ca2+]i more in LES (550 ± 22 nmol/l) than EB (250 ± 15 nmol/l, P < 0.001). Subsequent external application of 1 mmol/l Ca2+ increased [Ca2+]i more in LES (585 ± 35 nmol/l) than EB (295 ± 21 nmol/l, P < 0.001), indicating enhanced CCE in LES. This demonstrates CCE and TRPC transcriptional expression in human esophageal smooth muscle. In LES cells, enhanced CCE and expression of TRPC3 and TRPC4 may contribute to the physiological characteristics that distinguish LES from EB.

TRPC4 forms store-operated Ca2+ channels in mouse mesangial cells

2004 ◽  
Vol 287 (2) ◽  
pp. C357-C364 ◽  
Author(s):  
Xiaoxia Wang ◽  
Jennifer L. Pluznick ◽  
Peilin Wei ◽  
Babu J. Padanilam ◽  
Steven C. Sansom
Keyword(s):  
Transient Receptor Potential ◽  
Mesangial Cells ◽  
Receptor Potential ◽  
Immunocytochemical Staining ◽  
Rt Pcr ◽  
Fura 2 ◽  
Intracellular Ca ◽  
Transient Receptor ◽  
Ca2 Channels

Studies were performed to identify the molecular component responsible for store-operated Ca2+ entry in murine mesangial cells (MMC). Because the canonical transient receptor potential (TRPC) family of proteins was previously shown to comprise Ca2+-selective and -nonselective cation channels in a variety of cells, we screened TRPC1–TRPC7 with the use of molecular methods and the fura 2 method to determine their participation as components of the mesangial store-operated Ca2+ (SOC) channel. Using TRPC-specific primers and RT-PCR, we found that cultured MMC contained mRNA for TRPC1 and TRPC4 but not for TRPC2, TRPC3, TRPC5, TRPC6, and TRPC7. Immunocytochemical staining of MMC revealed predominantly cytoplasmic expression of TRPC1 and plasmalemmal expression of TRPC4. The role of TRPC4 in SOC was determined with TRPC4 antisense and fura 2 ratiometric measurements of intracellular Ca2+ concentration ([Ca2+]i). SOC was measured as the increase in [Ca2+]i after extracellular Ca2+ was increased from <10 nM to 1 mM in the continued presence of thapsigargin. We found that TRPC4 antisense, which reduced plasmalemmal expression of TRPC4, inhibited SOC by 83%. Incubation with scrambled TRPC4 oligonucleotides did not affect SOC. Immunohistochemical staining identified expressed TRPC4 in the glomeruli of mouse renal sections. The results of RT-PCR performed to distinguish between TRPC4-α and TRPC4-β were consistent with expression of both isoforms in brain but with only TRPC4-α expression in MMC. These studies show that TRPC4-α may form the homotetrameric SOC in mouse mesangial cells.

Mibefradil suppresses the proliferation of pulmonary artery smooth muscle cells

2016 ◽  
Vol 64 (1) ◽  
pp. 45-49 ◽  
Author(s):  
Hong-Hong Li ◽  
Li-Jian Xie ◽  
Ting-Ting Xiao ◽  
Min Huang ◽  
Jie Shen
Keyword(s):  
Smooth Muscle ◽  
Pulmonary Artery ◽  
Transient Receptor Potential ◽  
Critical Role ◽  
Receptor Potential ◽  
Channel Expression ◽  
Intracellular Ca ◽  
Pulmonary Arterial ◽  
Pulmonary Artery Smooth Muscle ◽  
Transient Receptor

Intracellular Ca2+ levels play a critical role in the regulation of vasodilation and vasoconstriction by stimulating pulmonary artery smooth muscle cell (PASMC) proliferation, which is important in the pathogenesis of pulmonary arterial hypertension (PAH); however, L-type Ca2+ channel antagonists are useful in only few patients with PAH. The present study sought to assess the effect of mibefradil, which blocks T-type Ca2+ channels, on PASMC proliferation and Ca2+ channel profile. Human PASMCs were stimulated with 25 ng/mL platelet-derived growth factor-BB (PDGF-BB) with and without 10 µM mibefradil or 100 nM sildenafil. After 48 or 72 h, PASMC proliferation and Ca2+ channel expression were assessed by MTT assays and western blot analysis, respectively. PDGF-BB-induced PASMC proliferation at 72 h (p<0.01), which was inhibited by both sildenafil and mibefradil (p<0.01). Transient receptor potential Ca2+ channel 6 (TRPC6) expression was significantly increased with PDGF-BB stimulation (p=0.009); however, no changes in TRPC1, TRPC3, CAV1.2, and CAV3.2 levels were observed. Although both TRPC1 and CAV1.2 expression levels were increased in PDGF-stimulated PASMCs on mibefradil and sildenafil treatment, it was not statistically significant (p=0.086 and 1.000, respectively). Mibefradil inhibits PDGF-BB-stimulated PASMC proliferation; however, the mechanism through which it functions remains to be determined. Further studies are required to elucidate the full therapeutic value of mibefradil for PAH.

scholarly journals Attenuation of Canonical Transient Receptor Potential-Like Channel 6 Expression Specifically Reduces the Diacylglycerol-Mediated Increase in Intracellular Calcium in Human Myometrial Cells

Endocrinology ◽  
2010 ◽  
Vol 151 (1) ◽  
pp. 406-416 ◽  
Author(s):  
Daesuk Chung ◽  
Yoon-Sun Kim ◽  
Jennifer N. Phillips ◽  
Aida Ulloa ◽  
Chun-Ying Ku ◽  
...  
Keyword(s):  
Smooth Muscle ◽  
Transient Receptor Potential ◽  
Contractile Activity ◽  
Receptor Potential ◽  
Myometrial Cells ◽  
Canonical Transient Receptor Potential ◽  
Voltage Dependent ◽  
Transient Receptor ◽  
Entry Mechanism

Abstract An increase in intracellular Ca2+ ([Ca2+]i) as a result of release of Ca2+ from intracellular stores or influx of extracellular Ca2+ contributes to the regulation of smooth muscle contractile activity. Human uterine smooth muscle cells exhibit receptor-, store-, and diacylglycerol (OAG)-mediated extracellular Ca2+-dependent increases in [Ca2+]i (SRCE) and express canonical transient receptor potential-like channels (TRPC) mRNAs (predominantly TRPC1, -4, and -6) that have been implicated in SRCE. To determine the role of TRPC6 in human myometrial SRCE, short hairpin RNA constructs were designed that effectively targeted a TRPC6 mRNA reporter for degradation. One sequence was used to produce an adenovirus construct (TC6sh1). TC6sh1 reduced TRPC6 mRNA but not TRPC1, -3, -4, -5, or -7 mRNAs in PHM1-41 myometrial cells. Compared with uninfected cells or cells infected with empty vector, the increase in [Ca2+]i in response to OAG was specifically inhibited by TC6sh1, whereas SRCE responses elicited by either oxytocin or thapsigargin were not changed. Similar findings were observed in primary pregnant human myometrial cells. When PHM1-41 cells were activated by OAG in the absence of extracellular Na+, the increase in [Ca2+]i was partially reduced. Furthermore, pretreatment with nifedipine, an L-type calcium channel blocker, also partially reduced the OAG-induced [Ca2+]i increase. Similar effects were observed in primary human myometrial cells. These findings suggest that OAG activates channels containing TRPC6 in myometrial cells and that these channels act via both enhanced Na+ entry coupled to activation of voltage-dependent Ca2+ entry channels and a nifedipine-independent Ca2+ entry mechanism to promote elevation of intracellular Ca2+.

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