Ectopic expression of caveolin-1 restores physiological contractile response of aged colonic smooth muscle

2007 ◽  
Vol 293 (1) ◽  
pp. G240-G249 ◽  
Author(s):  
Sita Somara ◽  
Robert R. Gilmont ◽  
Jeffrery R. Martens ◽  
Khalil N. Bitar

Reduced colonic motility has been observed in aged rats with a parallel reduction in acetylcholine (ACh)-induced myosin light chain (MLC20) phosphorylation. MLC20 phosphorylation during smooth muscle contraction is maintained by a coordinated signal transduction cascade requiring both PKC-α and RhoA. Caveolae are membrane microdomains that permit rapid and efficient coordination of different signal transduction cascades leading to sustained smooth muscle contraction of the colon. Here, we show that normal physiological contraction can be reinstated in aged colonic smooth muscle cells (CSMCs) upon transfection with wild-type caveolin-1 through the activation of both the RhoA/Rho kinase and PKC pathways. Our data demonstrate that impaired contraction in aging is an outcome of altered membrane translocation of PKC-α and RhoA with a concomitant reduction in the association of these molecules with the caveolae-specific protein caveolin-1, resulting in a parallel decrease in the myosin phosphatase-targeting subunit (MYPT) and CPI-17 phosphorylation. Decreased MYPT and CPI-17 phosphorylation activates MLC phosphatase activity, resulting in MLC20 dephosphorylation, which may be responsible for decreased colonic motility in aged rats. Importantly, transfection of CSMCs from aged rats with wild-type yellow fluorescent protein-caveolin-1 cDNA restored translocation of RhoA and PKC-α and phosphorylation of MYPT, CPI-17, and MLC20, thereby restoring the contractile response to levels comparable with young adult rats. Thus, we propose that caveolin-1 gene transfer may represent a promising therapeutic treatment to correct the age-related decline in colonic smooth muscle motility.

1985 ◽  
Vol 68 (s10) ◽  
pp. 55s-63s ◽  
Author(s):  
John C. McGrath

1. The effects of varying [Ca2+]o on the contraction of smooth muscle by different α-adrenoceptor agonists were examined on rat isolated anococcygeus muscle. Agonists were tested in the presence of various [Ca2+]o or ‘Ca2+-re-addition curves’ were constructed. In some experiments the [Ca2+]free was buffered with EGTA and nitrilotriacetic acid. The components of the response which were revealed were further analysed by using drugs which modify Ca2+ mobilization. 2. Three separate elements in the contractile response were identified: (i) an initial transient contraction, due to intracellular Ca2+ release could be isolated with [Ca2+]o between 1 nmol/l and 3 μmol/l (this could be obtained only with noradrenaline, phenylephrine and amidephrine); (ii) a nifedipine-sensitive response requiring [Ca2+]o of 3 μmol/l or more; (iii) a nifedipine-resistant response requiring [Ca2+]o of 100 μmol/l or more. Presumably (ii) and (iii) involve the entry of Ca2+o: they could be obtained with all agonists tested, including these above, methoxamine, indanidine and xylazine. 3. The results are discussed in relation to the possibility of distinct types of response and their relationship to subgroups of receptors or agonists. It is concluded that there is a continuous spectrum of activity across the agonist range and that this is likely to correlate with ‘efficacy’ at a single α1 receptor type.


1999 ◽  
Vol 277 (2) ◽  
pp. G445-G454 ◽  
Author(s):  
Adenike I. Ibitayo ◽  
Jeanette Sladick ◽  
Sony Tuteja ◽  
Otto Louis-Jacques ◽  
Hirotaka Yamada ◽  
...  

Sustained smooth muscle contraction is mediated by protein kinase C (PKC) through a signal transduction cascade leading to contraction. Heat-shock protein 27 (HSP27) appears to be the link between these two major events, i.e., signal transduction and sustained smooth muscle contraction. We have investigated the involvement of HSP27 in signal transduction and HSP27 association with contractile proteins (e.g., actin, myosin, tropomyosin, and caldesmon) resulting in sustained smooth muscle contraction. We have carried out confocal microscopy to investigate the cellular reorganization and colocalization of proteins and immunoprecipitation of HSP27 with actin, myosin, tropomyosin, and caldesmon as detected by sequential immunoblotting. Our results indicate that 1) translocation of Raf-1 to the membrane when stimulated with ceramide is inhibited by vasoactive intestinal peptide (VIP), a relaxant neuropeptide; 2) PKC-α and mitogen-activated protein kinase translocate and colocalize on the membrane in response to ceramide, and PKC-α translocation is inhibited by VIP; 3) HSP27 colocalizes with actin when contraction occurs; and 4) HSP27 immunoprecipitates with actin and with the contractile proteins myosin, tropomyosin, and caldesmon. We propose a model in which HSP27 is involved in sustained smooth muscle contraction and modulates the interaction of actin, myosin, tropomyosin, and caldesmon.


2013 ◽  
Vol 25 (1) ◽  
pp. 129-141 ◽  
Author(s):  
Ju-Hyun Kim ◽  
Lim-Kyu Lee ◽  
Won-Deok Lee ◽  
Jeong-Uk Lee ◽  
Mee-Young Kim ◽  
...  

Digestion ◽  
2006 ◽  
Vol 73 (4) ◽  
pp. 249-258 ◽  
Author(s):  
Xin-Min Si ◽  
Lei Huang ◽  
Shelley Chireyath Paul ◽  
Ping An ◽  
He-Sheng Luo

2007 ◽  
Vol 292 (1) ◽  
pp. C423-C431 ◽  
Author(s):  
Li Liu ◽  
Yukisato Ishida ◽  
Gbolahan Okunade ◽  
Gail J. Pyne-Geithman ◽  
Gary E. Shull ◽  
...  

We previously showed that plasma membrane Ca2+-ATPase (PMCA) activity accounted for 25–30% of relaxation in bladder smooth muscle ( 8 ). Among the four PMCA isoforms only PMCA1 and PMCA4 are expressed in smooth muscle. To address the role of these isoforms, we measured cytosolic Ca2+ ([Ca2+]i) using fura-PE3 and simultaneously measured contractility in bladder smooth muscle from wild-type (WT), Pmca1+/−, Pmca4+/−, Pmca4−/−, and Pmca1+/− Pmca4−/− mice. There were no differences in basal [Ca2+]i values between bladder preparations. KCl (80 mM) elicited both larger forces (150–190%) and increases in [Ca2+]i (130–180%) in smooth muscle from Pmca1+/− and Pmca1+/− Pmca4−/− bladders than those in WT or Pmca4−/−. The responses to carbachol (CCh: 10 μM) were also greater in Pmca1+/− (120–150%) than in WT bladders. In contrast, the responses in Pmca4−/− and Pmca1+/− Pmca4−/− bladders to CCh were significantly smaller (40–50%) than WT. The rise in half-times of force and [Ca2+]i increases in response to KCl and CCh, and the concomitant half-times of their decrease upon washout of agonist were prolonged in Pmca4−/− (130–190%) and Pmca1+/− Pmca4−/− (120–250%) bladders, but not in Pmca1+/− bladders with respect to WT. Our evidence indicates distinct isoform functions with the PMCA1 isoform involved in overall Ca2+ clearance, while PMCA4 is essential for the [Ca2+]i increase and contractile response to the CCh receptor-mediated signal transduction pathway.


1988 ◽  
Vol 66 (6) ◽  
pp. 820-825 ◽  
Author(s):  
Marian E. Addy ◽  
John F. Burka

Three fractions (n-butanol, F2, and L5), isolated from an aqueous extract of Desmodium adscendens, a plant used in Ghana for the management of asthma, were evaluated for their pharmacological activity using ovalbumin and arachidonic acid-induced contractions of guinea pig airways. All three fractions inhibited the ovalbumin-induced contractions of indomethacin-pretreated tracheal spirals from sensitized animals dose dependently, but only L5 and n-butanol inhibited such contractions in the absence of indomethacin. The concentrations required to inhibit ovalbumin-induced contractions of lung parenchymal strips were threefold higher than with trachea. The contractile response over a 60-min period was divided into three phases. F2 and n-butanol inhibited all phases, whereas L5 inhibited only the late phase. n-Butanol and L5 inhibited arachidonic acid-induced contractions on indomethacin-pretreated tracheal spirals, a leukotriene-dependent reaction. There was no inhibition of arachidonic acid-induced contractions of lung parenchymal strips, which is largely a thromboxane-dependent reaction. The results suggest that D. adscendens contains several pharmacologically active substances that can inhibit allergic airway smooth muscle contraction at multiple sites, including the synthesis and (or) activity of the bronchoconstrictor leukotrienes.


2015 ◽  
Vol 309 (7) ◽  
pp. L736-L746 ◽  
Author(s):  
David I. Kasahara ◽  
Joel A. Mathews ◽  
Chan Y. Park ◽  
Youngji Cho ◽  
Gabrielle Hunt ◽  
...  

Ozone causes airway hyperresponsiveness (AHR) and pulmonary inflammation. Rho kinase (ROCK) is a key regulator of smooth muscle cell contraction and inflammatory cell migration. To determine the contribution of the two ROCK isoforms ROCK1 and ROCK2 to ozone-induced AHR, we exposed wild-type, ROCK1+/−, and ROCK2+/− mice to air or ozone (2 ppm for 3 h) and evaluated mice 24 h later. ROCK1 or ROCK2 haploinsufficiency did not affect airway responsiveness in air-exposed mice but significantly reduced ozone-induced AHR, with a greater reduction in ROCK2+/− mice despite increased bronchoalveolar lavage (BAL) inflammatory cells in ROCK2+/− mice. Compared with wild-type mice, ozone-induced increases in BAL hyaluronan, a matrix protein implicated in ozone-induced AHR, were lower in ROCK1+/− but not ROCK2+/− mice. Ozone-induced increases in other inflammatory moieties reported to contribute to ozone-induced AHR (IL-17A, osteopontin, TNFα) were not different in wild-type vs. ROCK1+/− or ROCK2+/− mice. We also observed a dose-dependent reduction in ozone-induced AHR after treatment with the ROCK1/ROCK2 inhibitor fasudil, even though fasudil was administered after induction of inflammation. Ozone increased pulmonary expression of ROCK2 but not ROCK1 or RhoA. A ROCK2 inhibitor, SR3677, reduced contractile forces in primary human airway smooth muscle cells, confirming a role for ROCK2 in airway smooth muscle contraction. Our results demonstrate that ozone-induced AHR requires ROCK. Whereas ROCK1-dependent changes in hyaluronan may contribute to ROCK1's role in O3-induced AHR, the role of ROCK2 is downstream of inflammation, likely at the level of airway smooth muscle contraction.


1991 ◽  
Vol 260 (4) ◽  
pp. L207-L211 ◽  
Author(s):  
G. H. Gurtner ◽  
T. Burke-Wolin

Oxidants have complex effects on pulmonary vascular reactivity. They can stimulate production of vasoconstrictor arachidonate mediators and can also cause vasodilation through activation of guanylate cyclase. Oxidants can also inactivate vasomotor phenomenon by interfering with mechanisms of signal transduction or smooth muscle contraction. The final physiological response depends on the balance of these complex actions.


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