Abstract

The contractile properties of smooth muscle are broadly classified as phasic (fast) and tonic (slow). Phasic smooth muscle is characterized by a rapid rates of force activation, force relaxation and Vmax, whereas tonic smooth muscle is characterized by slow rates of force activation, force relaxation and Vmax. However, the molecular mechanism that regulates the contractile properties of smooth muscle is unknown. The overall goal of this grant is to determine the molecular mechanism for the contractile properties of smooth muscle and to elucidate the mechanism for fast and slow contractile properties. Our hypothesis is that splice variant isoforms of contractile proteins determine the contractile properties of smooth muscle.
The specific aims to test this hypothesis are to determine if splice variants of MLC17 (Specific Aim 1), MHC (Specific Aim 2) and MLC phosphatase (Specific Aim 3) are molecular determinants of the contractile properties of smooth muscle. We will also determine if splice variants isoforms of MLC phosphatase effect either the magnitude or sensitivity of agonist induced force enhancement (Specific Aim 3). To test these Specific Aims we will force the expression of both splice variant isoforms of MLC17, MHC and MLC phosphatase in cultured embryonic aortic and gizzard smooth muscle cells. We will determine the effects of the expression of the isoform normally present or not expressed in the cultured aortic and gizzard smooth muscle cells on the mechanical properties of cultured smooth muscle cells. After forcing the expression of a single contractile protein, we will determine the maximum force, the rates of force activation and force relaxation, Vmax, and MLC20 phosphorylation of single cultured smooth muscle cells and compare the results to those obtained in the non-transfected controls. These experiments will elucidate the effects of the expression of a single contractile protein, in isolation, on the mechanical properties of cultured smooth muscle cells. The results of these studies should elucidate the mechanism that determines the contractile properties of smooth muscle, and form a foundation for future investigation of how smooth muscle contractility is altered by disease states.

  Funding Agency

Agency
National Institute of Health (NIH)
Institute
National Heart, Lung, and Blood Institute (NHLBI)
Type
Research Project (R01)
Project #
5R01HL064137-02
Application #
6390597
Study Section
Experimental Cardiovascular Sciences Study Section (ECS)
Program Officer
Goldman, Stephen
Project Start
2000-08-07
Project End
2004-07-31
Budget Start
2001-08-01
Budget End
2002-07-31
Support Year
2
Fiscal Year
2001
Total Cost
$306,000
Indirect Cost

  Institution

Name
Case Western Reserve University
Department
Physiology
Type
Schools of Medicine
DUNS #
077758407
City
Cleveland
State
OH
Country
United States
Zip Code
44106

  Publications

Nowakowski, Sarah G; Kolwicz, Stephen C; Korte, Frederick Steven et al. (2013) Transgenic overexpression of ribonucleotide reductase improves cardiac performance. Proc Natl Acad Sci U S A 110:6187-92
Yuen, Samantha L; Ogut, Ozgur; Brozovich, Frank V (2009) Nonmuscle myosin is regulated during smooth muscle contraction. Am J Physiol Heart Circ Physiol 297:H191-9
Ogut, Ozgur; Brozovich, Frank V (2008) The potential role of MLC phosphatase and MAPK signalling in the pathogenesis of vascular dysfunction in heart failure. J Cell Mol Med 12:2158-64
Ogut, Ozgur; Yuen, Samantha L; Brozovich, Frank V (2007) Regulation of the smooth muscle contractile phenotype by nonmuscle myosin. J Muscle Res Cell Motil 28:409-14
Given, Allison M; Ogut, Ozgur; Brozovich, Frank V (2007) MYPT1 mutants demonstrate the importance of aa 888-928 for the interaction with PKGIalpha. Am J Physiol Cell Physiol 292:C432-9
El-Toukhy, Amr; Given, Allison M; Ogut, Ozgur et al. (2006) PHI-1 interacts with the catalytic subunit of myosin light chain phosphatase to produce a Ca(2+) independent increase in MLC(20) phosphorylation and force in avian smooth muscle. FEBS Lett 580:5779-84
El-Touhky, Amr; Given, Allison M; Cochard, Audrey et al. (2005) PHI-1 induced enhancement of myosin phosphorylation in chicken smooth muscle. FEBS Lett 579:4271-7
Karagiannis, Peter; Babu, G J; Periasamy, M et al. (2004) Myosin heavy chain isoform expression regulates shortening velocity in smooth muscle: studies using an SMB KO mouse line. J Muscle Res Cell Motil 25:149-58
Huang, Qi Quan; Fisher, Steven A; Brozovich, Frank V (2004) Unzipping the role of myosin light chain phosphatase in smooth muscle cell relaxation. J Biol Chem 279:597-603
Brozovich, Frank V (2003) Rho signaling: agonist stimulation and depolarization come together. Circ Res 93:481-3

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