RHO a regulates sustaned smooth muscle contraction through cytoskeletal reorganization of the actin binding protein HSP27

1998 ◽  
Vol 114 ◽  
pp. A858
Author(s):  
P. Wang ◽  
K.N. Bitar
Keyword(s):  
Smooth Muscle ◽  
Muscle Contraction ◽  
Binding Protein ◽  
Smooth Muscle Contraction ◽  
Actin Binding ◽  
Cytoskeletal Reorganization ◽  
Actin Binding Protein ◽  
Rho A

Rho A regulates sustained smooth muscle contraction through cytoskeletal reorganization of HSP27

1998 ◽  
Vol 275 (6) ◽  
pp. G1454-G1462 ◽  
Author(s):  
Pinglang Wang ◽  
Khalil N. Bitar
Keyword(s):  
Smooth Muscle ◽  
Protein Kinase ◽  
Muscle Contraction ◽  
Smooth Muscle Contraction ◽  
Dominant Negative ◽  
Mitogen Activated Protein Kinase ◽  
Actin Binding ◽  
C3 Exoenzyme ◽  
Mitogen Activated Protein ◽  
Rho A

The ras-related protein Rho p21 regulates various actin-dependent functions, including smooth muscle contraction. However, the precise mechanism of action of Rho p21 is still not clear. We report here that Rho A is a key regulator of agonist-induced contractile effects in rabbit colonic smooth muscle. Endothelin-1 and C2 ceramide were used. Both seem to activate phosphoinositide 3-kinase (PI 3-kinase) through G protein and pp60 src , respectively. Immunoprecipitation and immunoblotting revealed one form of 21-kDa Rho A that translocated from the cytosol to the membrane in response to stimulation by either endothelin (10−7 M) or ceramide (10−7 M) (∼30% increase at 30 s that was sustained at 4 min). The translocation of Rho A to the membrane was confirmed by immunostaining. The translocation of Rho A was inhibited by Clostridium botulinum C3 exoenzyme, which ADP ribosylated Rho A, but was not inhibited by the pp60 src inhibitor herbimycin A or by the protein kinase C (PKC) inhibitor calphostin C, suggesting that Rho A may be upstream of pp60 src and PKC or may belong to a different pathway than these proteins. Both ceramide- and endothelin-induced PI 3-kinase activation was inhibited by C3 exoenzyme pretreatment. However, the C3 exoenzyme inhibited endothelin- but not ceramide-induced mitogen-activated protein kinase phosphorylation, indicating that Rho regulates ceramide- and endothelin-induced contraction through different pathways. Furthermore, the dominant negative form of Rho (N19Rho) inhibited the actin binding protein, 27-kDa heat shock protein (HSP27), reorganization in response to ceramide and endothelin observed under confocal microscopy.

Calcium-dependent mechanisms of regulation of smooth muscle contraction

1991 ◽  
Vol 69 (12) ◽  
pp. 771-800 ◽  
Author(s):  
Michael P. Walsh
Keyword(s):  
Smooth Muscle ◽  
Muscle Contraction ◽  
Light Chain ◽  
Myosin Light Chain Kinase ◽  
Myosin Light Chain ◽  
Binding Protein ◽  
Smooth Muscle Contraction ◽  
Light Chains ◽  
Contractile State ◽  
Calmodulin Binding

The contractile state of smooth muscle is regulated primarily by the sarcoplasmic (cytosolic) free Ca2+ concentration. A variety of stimuli that induce smooth muscle contraction (e.g., membrane depolarization, α-adrenergic and muscarinic agonists) trigger an increase in sarcoplasmic free [Ca2+] from resting levels of 120–270 to 500–700 nM. At the elevated [Ca2+], Ca2+ binds to calmodulin, the ubiquitous and multifunctional Ca2+-binding protein. The interaction of Ca2+ with CaM induces a conformational change in the Ca2+-binding protein with exposure of a site(s) of interaction with target proteins, the most important of which in the context of smooth muscle contraction is the enzyme myosin light chain kinase. The interaction of calmodulin with myosin light chain kinase results in activation of the kinase that catalyzes phosphorylation of myosin at serine-19 of each of the two 20-kDa light chains (native myosin is a hexamer composed of two heavy chains (230 kDa each) and two pairs of light chains (one pair of 20 kDa each and the other pair of 17 kDa each)). This simple phosphorylation reaction triggers cycling of myosin cross-bridges along actin filaments and the development of force. Relaxation of the muscle follows removal of Ca2+ from the sarcoplasm, whereupon calmodulin dissociates from myosin light chain kinase regenerating the inactive kinase; myosin is dephosphorylated by myosin light chain phosphatase(s), whereupon it dissociates and remains detached from the actin filament and the muscle relaxes. A substantial body of evidence has been accumulated in support of this central role of myosin phosphorylation–dephosphorylation in the regulation of smooth muscle contraction. However, a wide range of physiological and biochemical studies supports the existence of additional, secondary Ca2+-dependent mechanisms that can modulate or fine-tune the contractile state of the smooth muscle cell. Three such mechanisms have emerged: (i) the actin-, tropomyosin-, and calmodulin-binding protein, calponin; (ii) the actin-, myosin-, tropomyosin-, and calmodulin-binding protein, caldesmon; and (iii) the Ca2+- and phospholipid-dependent protein kinase (protein kinase C).Key words: smooth muscle, Ca2+, myosin phosphorylation, regulation of contraction.

scholarly journals Localization of the actin-binding protein fesselin in chicken smooth muscle

2008 ◽  
Vol 131 (2) ◽  
pp. 191-196 ◽  
Author(s):  
Randall H. Renegar ◽  
Joseph M. Chalovich ◽  
Barbara D. Leinweber ◽  
Joan T. Zary ◽  
Mechthild M. Schroeter
Keyword(s):  
Smooth Muscle ◽  
Binding Protein ◽  
Actin Binding ◽  
Actin Binding Protein

scholarly journals Impaired Relaxation of Airway Smooth Muscle in Mice Lacking the Actin-Binding Protein Gelsolin

2017 ◽  
Vol 56 (5) ◽  
pp. 628-636 ◽  
Author(s):  
Maya Mikami ◽  
Yi Zhang ◽  
Jennifer Danielsson ◽  
Tiarra Joell ◽  
Hwan Mee Yong ◽  
...  
Keyword(s):  
Smooth Muscle ◽  
Airway Smooth Muscle ◽  
Binding Protein ◽  
Actin Binding ◽  
Actin Binding Protein

scholarly journals Role of thin-filament regulatory proteins in relaxation of colonic smooth muscle contraction

2009 ◽  
Vol 297 (5) ◽  
pp. G958-G966 ◽  
Author(s):  
Sita Somara ◽  
Robert Gilmont ◽  
Khalil N. Bitar
Keyword(s):  
Smooth Muscle ◽  
Muscle Contraction ◽  
Thin Filament ◽  
Smooth Muscle Contraction ◽  
Regulatory Proteins ◽  
Actin Binding ◽  
Thin Filament Regulation ◽  
Actomyosin Interaction ◽  
Regulation Of Contraction

Coordinated regulation of smooth muscle contraction and relaxation is required for colonic motility. Contraction is associated with phosphorylation of myosin light chain (MLC20) and interaction of actin with myosin. Thin-filament regulation of actomyosin interaction is modulated by two actin-binding regulatory proteins: tropomyosin (TM) and caldesmon (CaD). TM and CaD are known to play crucial role in actomyosin interaction promoting contraction. Contraction is associated with phosphorylation of the small heat shock protein HSP27, concomitant with the phosphorylation of TM and CaD. Phosphorylation of HSP27 is attributed as being the prime modulator of thin-filament regulation of contraction. Preincubation of colonic smooth muscle cells (CSMC) with the relaxant neurotransmitter vasoactive intestinal peptide (VIP) showed inhibition in phosphorylation of HSP27 (ser78). Attenuation of HSP27 phosphorylation can result in modulation of thin-filament-mediated regulation of contraction leading to relaxation; thus the role of thin-filament regulatory proteins in a relaxation milieu was investigated. Preincubation of CSMC with VIP exhibited a decrease in phosphorylation of TM and CaD. Furthermore, CSMC preincubated with VIP showed a reduced association of TM with HSP27 and with phospho-HSP27 (ser78) whereas there was reduced dissociation of TM from CaD and from phospho-CaD. We thus propose that, in addition to alteration in phosphorylation of MLC20, relaxation is associated with alterations in thin-filament-mediated regulation that results in termination of contraction.

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