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Different Localizations and Cellular Behaviors of Leiomodin and Tropomodulin in Mature Cardiomyocyte Sarcomeres

Leiomodin (Lmod) is a muscle-specific F-actin–nucleating protein that is related to the F-actin pointed-end–capping protein tropomodulin (Tmod). However, Lmod contains a unique ∼150-residue C-terminal extension that is required for its strong nucleating activity. Overexpression or depletion of Lmod...

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Autores principales: Skwarek-Maruszewska, Aneta, Boczkowska, Malgorzata, Zajac, Allison L., Kremneva, Elena, Svitkina, Tatyana, Dominguez, Roberto, Lappalainen, Pekka
Formato: Texto
Lenguaje:English
Publicado: The American Society for Cell Biology 2010
Materias:
Acceso en línea:https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2947471/
https://www.ncbi.nlm.nih.gov/pubmed/20685966
http://dx.doi.org/10.1091/mbc.E10-02-0109
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author Skwarek-Maruszewska, Aneta
Boczkowska, Malgorzata
Zajac, Allison L.
Kremneva, Elena
Svitkina, Tatyana
Dominguez, Roberto
Lappalainen, Pekka
author_facet Skwarek-Maruszewska, Aneta
Boczkowska, Malgorzata
Zajac, Allison L.
Kremneva, Elena
Svitkina, Tatyana
Dominguez, Roberto
Lappalainen, Pekka
author_sort Skwarek-Maruszewska, Aneta
collection PubMed
description Leiomodin (Lmod) is a muscle-specific F-actin–nucleating protein that is related to the F-actin pointed-end–capping protein tropomodulin (Tmod). However, Lmod contains a unique ∼150-residue C-terminal extension that is required for its strong nucleating activity. Overexpression or depletion of Lmod compromises sarcomere organization, but the mechanism by which Lmod contributes to myofibril assembly is not well understood. We show that Tmod and Lmod localize through fundamentally different mechanisms to the pointed ends of two distinct subsets of actin filaments in myofibrils. Tmod localizes to two narrow bands immediately adjacent to M-lines, whereas Lmod displays dynamic localization to two broader bands, which are generally more separated from M-lines. Lmod's localization and F-actin nucleation activity are enhanced by interaction with tropomyosin. Unlike Tmod, the myofibril localization of Lmod depends on sustained muscle contraction and actin polymerization. We further show that Lmod expression correlates with the maturation of myofibrils in cultured cardiomyocytes and that it associates with sarcomeres only in differentiated myofibrils. Collectively, the data suggest that Lmod contributes to the final organization and maintenance of sarcomere architecture by promoting tropomyosin-dependent actin filament nucleation.
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spelling pubmed-29474712010-12-16 Different Localizations and Cellular Behaviors of Leiomodin and Tropomodulin in Mature Cardiomyocyte Sarcomeres Skwarek-Maruszewska, Aneta Boczkowska, Malgorzata Zajac, Allison L. Kremneva, Elena Svitkina, Tatyana Dominguez, Roberto Lappalainen, Pekka Mol Biol Cell Articles Leiomodin (Lmod) is a muscle-specific F-actin–nucleating protein that is related to the F-actin pointed-end–capping protein tropomodulin (Tmod). However, Lmod contains a unique ∼150-residue C-terminal extension that is required for its strong nucleating activity. Overexpression or depletion of Lmod compromises sarcomere organization, but the mechanism by which Lmod contributes to myofibril assembly is not well understood. We show that Tmod and Lmod localize through fundamentally different mechanisms to the pointed ends of two distinct subsets of actin filaments in myofibrils. Tmod localizes to two narrow bands immediately adjacent to M-lines, whereas Lmod displays dynamic localization to two broader bands, which are generally more separated from M-lines. Lmod's localization and F-actin nucleation activity are enhanced by interaction with tropomyosin. Unlike Tmod, the myofibril localization of Lmod depends on sustained muscle contraction and actin polymerization. We further show that Lmod expression correlates with the maturation of myofibrils in cultured cardiomyocytes and that it associates with sarcomeres only in differentiated myofibrils. Collectively, the data suggest that Lmod contributes to the final organization and maintenance of sarcomere architecture by promoting tropomyosin-dependent actin filament nucleation. The American Society for Cell Biology 2010-10-01 /pmc/articles/PMC2947471/ /pubmed/20685966 http://dx.doi.org/10.1091/mbc.E10-02-0109 Text en © 2010 by The American Society for Cell Biology This article is distributed by The American Society for Cell Biology under license from the author(s). Two months after publication it is available to the public under an Attribution–Noncommercial–Share Alike 3.0 Unported Creative Commons License (http://creativecommons.org/licenses/by-nc-sa/3.0).
spellingShingle Articles
Skwarek-Maruszewska, Aneta
Boczkowska, Malgorzata
Zajac, Allison L.
Kremneva, Elena
Svitkina, Tatyana
Dominguez, Roberto
Lappalainen, Pekka
Different Localizations and Cellular Behaviors of Leiomodin and Tropomodulin in Mature Cardiomyocyte Sarcomeres
title Different Localizations and Cellular Behaviors of Leiomodin and Tropomodulin in Mature Cardiomyocyte Sarcomeres
title_full Different Localizations and Cellular Behaviors of Leiomodin and Tropomodulin in Mature Cardiomyocyte Sarcomeres
title_fullStr Different Localizations and Cellular Behaviors of Leiomodin and Tropomodulin in Mature Cardiomyocyte Sarcomeres
title_full_unstemmed Different Localizations and Cellular Behaviors of Leiomodin and Tropomodulin in Mature Cardiomyocyte Sarcomeres
title_short Different Localizations and Cellular Behaviors of Leiomodin and Tropomodulin in Mature Cardiomyocyte Sarcomeres
title_sort different localizations and cellular behaviors of leiomodin and tropomodulin in mature cardiomyocyte sarcomeres
topic Articles
url https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2947471/
https://www.ncbi.nlm.nih.gov/pubmed/20685966
http://dx.doi.org/10.1091/mbc.E10-02-0109
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