Caveolae-associated signalling in smooth muscle

2004 ◽  
Vol 82 (5) ◽  
pp. 289-299 ◽  
Author(s):  
Andreas Bergdahl ◽  
Karl Swärd
Keyword(s):  
Smooth Muscle ◽  
Transient Receptor Potential ◽  
Muscle Tone ◽  
Receptor Potential ◽  
Transgenic Animals ◽  
Transient Receptor Potential Channel ◽  
Structural Protein ◽  
Outward Currents ◽  
Transient Receptor

Caveolae are flask-shaped invaginations in the membrane that depend on the contents of cholesterol and on the structural protein caveolin. The organisation of caveolae in parallel strands between dense bands in smooth muscle is arguably unique. It is increasingly recognised, bolstered in large part by recent studies in caveolae deficient animals, that caveolae sequester and regulate a variety of signalling intermediaries. The role of caveolae in smooth muscle signal transduction, as inferred from studies on transgenic animals and in vitro approaches, is the topic of the current review. Both G-protein coupled receptors and tyrosine kinase receptors are believed to cluster in caveolae, and the exciting possibility that caveolae provide a platform for interactions between the sarcoplasmic reticulum and plasmalemmal ion channels is emerging. Moreover, messengers involved in Ca2+ sensitization of myosin phosphorylation and contraction may depend on caveolae or caveolin. Caveolae thus appear to constitute an important signalling domain that plays a role not only in regulation of smooth muscle tone, but also in proliferation, such as seen in neointima formation and atherosclerosis.Key words: caveolin, RhoA, transient receptor potential channel, endothelin, spontaneous transient outward currents.

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.

scholarly journals Design, Synthesis and In Vitro Experimental Validation of Novel TRPV4 Antagonists Inspired by Labdane Diterpenes

Marine Drugs ◽  
2020 ◽  
Vol 18 (10) ◽  
pp. 519
Author(s):  
Sarah Mazzotta ◽  
Gabriele Carullo ◽  
Aniello Schiano Moriello ◽  
Pietro Amodeo ◽  
Vincenzo Di Marzo ◽  
...  
Keyword(s):  
Transient Receptor Potential ◽  
Calcium Influx ◽  
Biological Activities ◽  
Receptor Potential ◽  
Transient Receptor Potential Channel ◽  
Design Synthesis ◽  
Cellular Assays ◽  
Transient Receptor ◽  
Trpv4 Channel

Labdane diterpenes are widespread classes of natural compounds present in variety of marine and terrestrial organisms and plants. Many of them represents “natural libraries” of compounds with interesting biological activities due to differently functionalized drimane nucleus exploitable for potential pharmacological applications. The transient receptor potential channel subfamily V member 4 (TRPV4) channel has recently emerged as a pharmacological target for several respiratory diseases, including the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection. Inspired by the labdane-like bicyclic core, a series of homodrimane-derived esters and amides was designed and synthesized by modifying the flexible tail in position 1 of (+)-sclareolide, an oxidized derivative of the bioactive labdane-type diterpene sclareol. The potency and selectivity towards rTRPV4 and hTRPV1 receptors were assessed by calcium influx cellular assays. Molecular determinants critical for eliciting TRPV4 antagonism were identified by structure-activity relationships. Among the selective TRPV4 antagonists identified, compound 6 was the most active with an IC50 of 5.3 μM. This study represents the first report of semisynthetic homodrimane TRPV4 antagonists, selective over TRPV1, and potentially useful as pharmacological tools for the development of novel TRPV4 channel modulators.

scholarly journals Inhibition of TRPC1/TRPC3 by PKG contributes to NO-mediated vasorelaxation

2009 ◽  
Vol 297 (1) ◽  
pp. H417-H424 ◽  
Author(s):  
Jie Chen ◽  
Randy F. Crossland ◽  
Muzamil M. Z. Noorani ◽  
Sean P. Marrelli
Keyword(s):  
Smooth Muscle ◽  
Patch Clamp ◽  
Sodium Nitroprusside ◽  
Transient Receptor Potential ◽  
Critical Role ◽  
Receptor Potential ◽  
Transient Receptor Potential Channel ◽  
No Donor ◽  
No Inhibition ◽  
Transient Receptor

Nitric oxide (NO) inhibits transient receptor potential channel 3 (TRPC3) channels via a PKG-dependent mechanism. We sought to determine 1) whether NO inhibition of TRPC3 occurs in freshly isolated smooth muscle cells (SMC); and 2) whether NO inhibition of TRPC3 channels contributes to NO-mediated vasorelaxation. We tested these hypotheses in freshly isolated rat carotid artery (CA) SMC using patch clamp and in intact CA by vessel myograph. We demonstrated TRPC3 expression in whole CA (mRNA and protein) that was localized to the smooth muscle layers. TRPC1 protein was also expressed and coimmunoprecipitated with TRPC3. Whole cell patch clamp demonstrated nonselective cation channel currents that were activated by UTP (60 μM) and completely inhibited by a TRPC channel inhibitor, La3+ (100 μM). The UTP-stimulated current ( IUTP) was also inhibited by intracellular application of anti-TRPC3 or anti-TRPC1 antibody, but not by anti-TRPC6 or anti-TRPC4 control antibodies. We next evaluated the NO signaling pathway on IUTP. Exogenous NO [( Z)-1-{ N-methyl- N-[6( N-methylammoniohexyl)amino]}diazen-1-ium-1,2-diolate (MAHMA NONOate)] or a cell-permeable cGMP analog (8-bromo-cGMP) significantly inhibited IUTP. Preapplication of a PKG inhibitor (KT5823) reversed the inhibition of MAHMA NONOate or 8-bromo-cGMP, demonstrating the critical role of PKG in NO inhibition of TRPC1/TRPC3. Intact CA segments were contracted with UTP (100 μM) in the presence or absence of La3+ (100 μM) and then evaluated for relaxation to an NO donor, sodium nitroprusside (1 nM to 1 μM). Relaxation to sodium nitroprusside was significantly reduced in the La3+ treatment group. We conclude that freshly isolated SMC express TRPC1/TRPC3 channels and that these channels are inhibited by NO/cGMP/PKG. Furthermore, NO contributes to vasorelaxation by inhibition of La3+-sensitive channels consistent with TRPC1/TRPC3.

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.

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