title: Hypertrophic cardiomyopathy associated Lys104Glu mutation in the myosin regulatory light chain causes diastolic disturbance in mice.
abstract: We have examined, for the first time, the effects of the familial hypertrophic cardiomyopathy (HCM)-associated Lys104Glu mutation in the myosin regulatory light chain (RLC). Transgenic mice expressing the Lys104Glu substitution (Tg-MUT) were generated and the results were compared to Tg-WT (wild-type human ventricular RLC) mice. Echocardiography with pulse wave Doppler in 6month-old Tg-MUT showed early signs of diastolic disturbance with significantly reduced E/A transmitral velocities ratio. Invasive hemodynamics in 6month-old Tg-MUT mice also demonstrated a borderline significant prolonged isovolumic relaxation time (Tau) and a tendency for slower rate of pressure decline, suggesting alterations in diastolic function in Tg-MUT. Six month-old mutant animals had no LV hypertrophy; however, at >13months they displayed significant hypertrophy and fibrosis. In skinned papillary muscles from 5 to 6month-old mice a mutation induced reduction in maximal tension and slower muscle relaxation rates were observed. Mutated cross-bridges showed increased rates of binding to the thin filaments and a faster rate of the power stroke. In addition, ~2-fold lower level of RLC phosphorylation was observed in the mutant compared to Tg-WT. In line with the higher mitochondrial content seen in Tg-MUT hearts, the MUT-myosin ATPase activity was significantly higher than WT-myosin, indicating increased energy consumption. In the in vitro motility assay, MUT-myosin produced higher actin sliding velocity under zero load, but the velocity drastically decreased with applied load in the MUT vs. WT myosin. Our results suggest that diastolic disturbance (impaired muscle relaxation, lower E/A) and inefficiency of energy use (reduced contractile force and faster ATP consumption) may underlie the Lys104Glu-mediated HCM phenotype.
authors.affiliation: University of Miami, Miller School of Medicine, Miami, FL 33136, United States.
authors.forename: Wenrui
authors.initials: W
authors.lastname: Huang
authors.affiliation: University of Miami, Miller School of Medicine, Miami, FL 33136, United States.
authors.forename: Jingsheng
authors.initials: J
authors.lastname: Liang
authors.affiliation: University of Miami, Miller School of Medicine, Miami, FL 33136, United States.
authors.forename: Katarzyna
authors.initials: K
authors.lastname: Kazmierczak
authors.affiliation: University of Miami, Miller School of Medicine, Miami, FL 33136, United States.
authors.forename: Priya
authors.initials: P
authors.lastname: Muthu
authors.affiliation: University of North Texas Health Science Center, Fort Worth, TX 76107, United States.
authors.forename: Divya
authors.initials: D
authors.lastname: Duggal
authors.affiliation: Boston University School of Medicine, Boston, MA 02118, United States.
authors.forename: Gerrie P
authors.initials: GP
authors.lastname: Farman
authors.affiliation: Johns Hopkins University School of Medicine, Baltimore, MD 21205, United States.
authors.forename: Lars
authors.initials: L
authors.lastname: Sorensen
authors.affiliation: Johns Hopkins University School of Medicine, Baltimore, MD 21205, United States.
authors.forename: Iraklis
authors.initials: I
authors.lastname: Pozios
authors.affiliation: Johns Hopkins University School of Medicine, Baltimore, MD 21205, United States.
authors.forename: Theodore P
authors.initials: TP
authors.lastname: Abraham
authors.affiliation: Boston University School of Medicine, Boston, MA 02118, United States.
authors.forename: Jeffrey R
authors.initials: JR
authors.lastname: Moore
authors.affiliation: University of North Texas Health Science Center, Fort Worth, TX 76107, United States.
authors.forename: Julian
authors.initials: J
authors.lastname: Borejdo
authors.affiliation: University of Miami, Miller School of Medicine, Miami, FL 33136, United States. Electronic address: dszczesna@med.miami.edu.
authors.forename: Danuta
authors.initials: D
authors.lastname: Szczesna-Cordary
mesh_terms: D000255:Adenosine Triphosphate / Q000378:metabolism; D000595:Amino Acid Sequence; D000818:Animals; D002118:Calcium / Q000378:metabolism; D002312:Cardiomyopathy, Hypertrophic / Q000000981:diagnostic imaging / Q000235:genetics* / Q000378:metabolism / Q000473:pathology; D003971:Diastole; D005786:Gene Expression Regulation; D006339:Heart Rate; D008297:Male; D051379:Mice; D008822:Mice, Transgenic; D008969:Molecular Sequence Data; D009126:Muscle Relaxation; D009154:Mutation; D009200:Myocardial Contraction; D032383:Myocytes, Cardiac / Q000378:metabolism* / Q000473:pathology; D018994:Myosin Light Chains / Q000235:genetics* / Q000378:metabolism; D010210:Papillary Muscles / Q000000981:diagnostic imaging / Q000378:metabolism* / Q000473:pathology; D061251:Primary Cell Culture; D015398:Signal Transduction; D046509:Tissue Culture Techniques; D018617:Ultrasonography, Doppler, Pulsed
chemical_list: D018994:Myosin Light Chains; D000255:Adenosine Triphosphate; D002118:Calcium
keywords: Contractile force; Echocardiography; Hypertrophic cardiomyopathy (HCM); Mutation; Myosin regulatory light chain; Transgenic mice