Calcium increases titin N2A binding to F-actin and regulated thin filaments

Samrat Dutta, Christopher Tsiros, Sai Lavanyaa Sundar, Humra Athar, Jeffrey Moore, Brent A Nelson, Matthew J Gage, Kiisa C Nishikawa

Research output: Contribution to journalArticle

5 Citations (Scopus)

Abstract

Mutations in titin are responsible for many cardiac and muscle diseases, yet the underlying mechanisms remain largely unexplained. Numerous studies have established roles for titin in muscle function, and Ca2+-dependent interactions between titin and actin have been suggested to play a role in muscle contraction. The present study used co-sedimentation assays, dynamic force spectroscopy (DFS), and in vitro motility (IVM) assays to determine whether the N2A region of titin, overlooked in previous studies, interacts with actin in the presence of Ca2+. Co-sedimentation demonstrated that N2A – F-actin binding increases with increasing protein and Ca2+ concentration, DFS demonstrated increased rupture forces and decreased koff in the presence of Ca2+, and IVM demonstrated a Ca2+-dependent reduction in motility of F-actin and reconstituted thin filaments in the presence of N2A. These results indicate that Ca2+ increases the strength and stability of N2A – actin interactions, supporting the hypothesis that titin plays a regulatory role in muscle contraction. The results further support a model in which N2A – actin binding in active muscle increases titin stiffness, and that impairment of this mechanism contributes to the phenotype in muscular dystrophy with myositis. Future studies are required to determine whether titin – actin binding occurs in skeletal muscle sarcomeres in vivo.

Original languageEnglish (US)
Article number14575
JournalScientific Reports
Volume8
Issue number1
DOIs
StatePublished - Dec 1 2018

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Connectin
Actins
Calcium
Muscle Contraction
Spectrum Analysis
Muscles
Sarcomeres
Myositis
Muscular Dystrophies
Rupture
Heart Diseases
Myocardium
Skeletal Muscle
Phenotype
Mutation

ASJC Scopus subject areas

  • General

Cite this

Calcium increases titin N2A binding to F-actin and regulated thin filaments. / Dutta, Samrat; Tsiros, Christopher; Sundar, Sai Lavanyaa; Athar, Humra; Moore, Jeffrey; Nelson, Brent A; Gage, Matthew J; Nishikawa, Kiisa C.

In: Scientific Reports, Vol. 8, No. 1, 14575, 01.12.2018.

Research output: Contribution to journalArticle

Dutta, Samrat ; Tsiros, Christopher ; Sundar, Sai Lavanyaa ; Athar, Humra ; Moore, Jeffrey ; Nelson, Brent A ; Gage, Matthew J ; Nishikawa, Kiisa C. / Calcium increases titin N2A binding to F-actin and regulated thin filaments. In: Scientific Reports. 2018 ; Vol. 8, No. 1.
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