Phosphorylation of tropomodulin1 contributes to the regulation of actin filament architecture in cardiac muscle

Katherine T Bliss; Takehiro Tsukada; Stefanie Mares Novak; Maxim V Dorovkov; Samar P Shah; Chinedu Nworu; Alla S Kostyukova; Carol C Gregorio

doi:10.1096/fj.13-246009

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Phosphorylation of tropomodulin1 contributes to the regulation of actin filament architecture in cardiac muscle

Journal article

Open access

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Phosphorylation of tropomodulin1 contributes to the regulation of actin filament architecture in cardiac muscle

Katherine T Bliss, Takehiro Tsukada, Stefanie Mares Novak, Maxim V Dorovkov, Samar P Shah, Chinedu Nworu, Alla S Kostyukova and Carol C Gregorio

The FASEB journal, Vol.28(9), pp.3987-3995

09/2014

DOI: https://doi.org/10.1096/fj.13-246009

Handle:

https://hdl.handle.net/2376/105999

PMCID: PMC4139905

PMID: 24891520

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https://doi.org/10.1096/fj.13-246009View

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Abstract

Animals, Newborn

Peptide Fragments - metabolism

Phosphorylation

Actin Cytoskeleton - metabolism

Immunoprecipitation

Mutagenesis, Site-Directed

Myocytes, Cardiac - cytology

Cells, Cultured

Actin Cytoskeleton - chemistry

Rats

Tropomodulin - genetics

Mutation - genetics

Blotting, Western

Myocardium - cytology

Tropomodulin - metabolism

Animals

Myocardium - metabolism

Myocytes, Cardiac - metabolism

Tropomodulin1 (Tmod1) is an actin-capping protein that plays an important role in actin filament pointed-end dynamics and length in striated muscle. No mechanisms have been identified to explain how Tmod1's functional properties are regulated. The purpose of this investigation was to explore the functional significance of the phosphorylation of Tmod1 at previously identified Thr54. Rat cardiomyocytes were assessed for phosphorylation of Tmod1 using Pro-Q Diamond staining and (32)P labeling. Green fluorescent protein-tagged phosphorylation-mimic (T54E) and phosphorylation-deficient (T54A) versions of Tmod1 were expressed in cultured cardiomyocytes, and the ability of these mutants to assemble and restrict actin lengths was observed. We report for the first time that Tmod1 is phosphorylated endogenously in cardiomyocytes, and phosphorylation at Thr54 causes a significant reduction in the ability of Tmod1 to assemble to the pointed end compared with that of the wild type (WT; 48 vs. 78%, respectively). In addition, overexpression of Tmod1-T54E restricts actin filament lengths by only ∼3%, whereas Tmod1-WT restricts the lengths significantly by ∼8%. Finally, Tmod1-T54E altered the actin filament-capping activity in polymerization assays. Taken together, our data suggest that pointed-end assembly and Tmod1's thin filament length regulatory function are regulated by its phosphorylation state.

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Title: Phosphorylation of tropomodulin1 contributes to the regulation of actin filament architecture in cardiac muscle
Creators: Katherine T Bliss - Department of Cellular and Molecular Medicine and Sarver Molecular Cardiovascular Research Program, University of Arizona, Tucson, Arizona, USA
Takehiro Tsukada - Department of Cellular and Molecular Medicine and Sarver Molecular Cardiovascular Research Program, University of Arizona, Tucson, Arizona, USA
Stefanie Mares Novak - Department of Cellular and Molecular Medicine and Sarver Molecular Cardiovascular Research Program, University of Arizona, Tucson, Arizona, USA
Maxim V Dorovkov - Department of Pharmacology and
Samar P Shah - Department of Neuroscience and Cell Biology, Robert Wood Johnson Medical School, Piscataway, New Jersey, USA; and
Chinedu Nworu - Department of Cellular and Molecular Medicine and Sarver Molecular Cardiovascular Research Program, University of Arizona, Tucson, Arizona, USA
Alla S Kostyukova - Department of Neuroscience and Cell Biology, Robert Wood Johnson Medical School, Piscataway, New Jersey, USA; and School of Chemical Engineering and Bioengineering, Washington State University, Pullman, Washington, USA
Carol C Gregorio - Department of Cellular and Molecular Medicine and Sarver Molecular Cardiovascular Research Program, University of Arizona, Tucson, Arizona, USA; gregorio@email.arizona.edu
Publication Details: The FASEB journal, Vol.28(9), pp.3987-3995
Academic Unit: Chemical Engineering and Bioengineering, School of
Publisher: United States
Grant note: 1F31HL 117520 / NHLBI NIH HHS HL108625 / NHLBI NIH HHS R01 GM081688 / NIGMS NIH HHS R01 HL083146 / NHLBI NIH HHS R01 HL081386 / NHLBI NIH HHS GM081688 / NIGMS NIH HHS R01 HL108625 / NHLBI NIH HHS F31 HL117520 / NHLBI NIH HHS HL081386 / NHLBI NIH HHS HL083146 / NHLBI NIH HHS
Identifiers: 99900546720701842
Language: English
Resource Type: Journal article