期刊
AMERICAN JOURNAL OF PHYSIOLOGY-HEART AND CIRCULATORY PHYSIOLOGY
卷 293, 期 1, 页码 H284-H291出版社
AMER PHYSIOLOGICAL SOC
DOI: 10.1152/ajpheart.00128.2007
关键词
familial hypertrophic cardiomyopathy; in vitro motility; force-velocity relationship; heart failure
资金
- NHLBI NIH HHS [R01 HL077280] Funding Source: Medline
- NIGMS NIH HHS [F32 GM020384] Funding Source: Medline
Point mutations in cardiac myosin, the heart's molecular motor, produce distinct clinical phenotypes: hypertrophic (HCM) and dilated (DCM) cardiomyopathy. Do mutations alter myosin's molecular mechanics in a manner that is predictive of the clinical outcome? We have directly characterized the maximal force-generating capacity (F-max) of two HCM (R403Q, R453C) and two DCM (S532P, F764L) mutant myosins isolated from homozygous mouse models using a novel load-clamped laser trap assay. F-max was 50% (R403Q) and 80% (R453C) greater for the HCM mutants compared with the wild type, whereas F-max was severely depressed for one of the DCM mutants (65% S532P). Although F-max was normal for the F764L DCM mutant, its actin-activated ATPase activity and actin filament velocity (V-actin) in a motility assay were significantly reduced ( Schmitt JP, Debold EP, Ahmad F, Armstrong A, Frederico A, Conner DA, Mende U, Lohse MJ, Warshaw D, Seidman CE, Seidman JG. Proc Natl Acad Sci USA 103: 14525-14530, 2006.). These F-max data combined with previous Vactin measurements suggest that HCM and DCM result from alterations to one or more of myosin's fundamental mechanical properties, with HCM-causing mutations leading to enhanced but DCM-causing mutations leading to depressed function. These mutation-specific changes in mechanical properties must initiate distinct signaling cascades that ultimately lead to the disparate phenotypic responses observed in HCM and DCM.
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