Muscle is essential for the function of the circulatory, urogenital, respiratory, and digestive systems. Although much is understood about the force-generating capacity of acto-myosin, little is known about how the contractile machinery is organized within muscle cells and about how it is stabilized during contraction cycles. Sites of actin filament anchorage represent key sites for organization, integration, and tethering of the contractile apparatus. The actin crosslinking protein, a-actinin, is concentrated at actin anchorage sites in muscle. We have identified members of two families of LIM domain proteins, the Cysteine-Rich Protein (CRP) family and the ALP-Enigma family as a-actinin binding partners. We have demonstrated that these proteins are enriched in muscle where they co-localize with a-actinin at actin filament anchorage sites. Here we propose to define the mechanisms by which these proteins contribute to muscle cytoarchitecture and function. By analysis of lossof-function mutations that we have generated, we will defme the contributions of these proteins to normal muscle structure and function. We will examine the consequences of these genetic alterations for the ultrastructural organization and molecular architecture of actin anchorage sites in muscle, including Z-discs, dense bodies, and regions of cell adhesion. We will identify the proteins that complex with CRP and ALPEnigma in order to gain a more comprehensive view of their molecular mechanisms of action. Regions of actin filament anchorage in muscle are proposed to play a critical role in muscle stability, and these areas may serve as architectural sensors that monitor the integrity and function of the contractile machinery. In humans, deficiencies in components of actin-anchorage sites are associated with cardiomyopathies. Therefore, our results will contribute to an understanding of both normal muscle function as well as aspects of muscle pathology.

Agency
National Institute of Health (NIH)
Institute
National Heart, Lung, and Blood Institute (NHLBI)
Type
Research Project (R01)
Project #
2R01HL060591-05
Application #
6545199
Study Section
Special Emphasis Panel (ZRG1-CDF-2 (02))
Program Officer
Ershow, Abby
Project Start
1998-07-01
Project End
2006-06-30
Budget Start
2002-07-01
Budget End
2003-06-30
Support Year
5
Fiscal Year
2002
Total Cost
$375,000
Indirect Cost
Name
University of Utah
Department
Biology
Type
Schools of Arts and Sciences
DUNS #
City
Salt Lake City
State
UT
Country
United States
Zip Code
84112
Lilly, Brenda; Clark, Kathleen A; Yoshigi, Masaaki et al. (2010) Loss of the serum response factor cofactor, cysteine-rich protein 1, attenuates neointima formation in the mouse. Arterioscler Thromb Vasc Biol 30:694-701
Clark, Kathleen A; Bland, Jennifer M; Beckerle, Mary C (2007) The Drosophila muscle LIM protein, Mlp84B, cooperates with D-titin to maintain muscle structural integrity. J Cell Sci 120:2066-77
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Chang, David F; Belaguli, Narasimhaswamy S; Iyer, Dinakar et al. (2003) Cysteine-rich LIM-only proteins CRP1 and CRP2 are potent smooth muscle differentiation cofactors. Dev Cell 4:107-18
Henderson, James R; Pomies, Pascal; Auffray, Charles et al. (2003) ALP and MLP distribution during myofibrillogenesis in cultured cardiomyocytes. Cell Motil Cytoskeleton 54:254-65
Henderson, James R; Brown, Doris; Richardson, James A et al. (2002) Expression of the gene encoding the LIM protein CRP2: a developmental profile. J Histochem Cytochem 50:107-11
Clark, Kathleen A; McElhinny, Abigail S; Beckerle, Mary C et al. (2002) Striated muscle cytoarchitecture: an intricate web of form and function. Annu Rev Cell Dev Biol 18:637-706
Lilly, B; Olson, E N; Beckerle, M C (2001) Identification of a CArG box-dependent enhancer within the cysteine-rich protein 1 gene that directs expression in arterial but not venous or visceral smooth muscle cells. Dev Biol 240:531-47
Harper, B D; Beckerle, M C; Pomies, P (2000) Fine mapping of the alpha-actinin binding site within cysteine-rich protein. Biochem J 350 Pt 1:269-74

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