title: Constitutive phosphorylation of cardiac myosin regulatory light chain prevents development of hypertrophic cardiomyopathy in mice.
abstract: Myosin light chain kinase (MLCK)-dependent phosphorylation of the regulatory light chain (RLC) of cardiac myosin is known to play a beneficial role in heart disease, but the idea of a phosphorylation-mediated reversal of a hypertrophic cardiomyopathy (HCM) phenotype is novel. Our previous studies on transgenic (Tg) HCM-RLC mice revealed that the D166V (Aspartate166 → Valine) mutation-induced changes in heart morphology and function coincided with largely reduced RLC phosphorylation in situ. We hypothesized that the introduction of a constitutively phosphorylated Serine15 (S15D) into the hearts of D166V mice would prevent the development of a deleterious HCM phenotype. In support of this notion, MLCK-induced phosphorylation of D166V-mutated hearts was found to rescue some of their abnormal contractile properties. Tg-S15D-D166V mice were generated with the human cardiac RLC-S15D-D166V construct substituted for mouse cardiac RLC and were subjected to functional, structural, and morphological assessments. The results were compared with Tg-WT and Tg-D166V mice expressing the human ventricular RLC-WT or its D166V mutant, respectively. Echocardiography and invasive hemodynamic studies demonstrated significant improvements of intact heart function in S15D-D166V mice compared with D166V, with the systolic and diastolic indices reaching those monitored in WT mice. A largely reduced maximal tension and abnormally high myofilament Ca(2+) sensitivity observed in D166V-mutated hearts were reversed in S15D-D166V mice. Low-angle X-ray diffraction study revealed that altered myofilament structures present in HCM-D166V mice were mitigated in S15D-D166V rescue mice. Our collective results suggest that expression of pseudophosphorylated RLC in the hearts of HCM mice is sufficient to prevent the development of the pathological HCM phenotype.
authors.affiliation: Department of Molecular and Cellular Pharmacology, University of Miami Miller School of Medicine, Miami, FL 33136;
authors.forename: Chen-Ching
authors.initials: CC
authors.lastname: Yuan
authors.affiliation: Department of Molecular and Cellular Pharmacology, University of Miami Miller School of Medicine, Miami, FL 33136;
authors.forename: Priya
authors.initials: P
authors.lastname: Muthu
authors.affiliation: Department of Molecular and Cellular Pharmacology, University of Miami Miller School of Medicine, Miami, FL 33136;
authors.forename: Katarzyna
authors.initials: K
authors.lastname: Kazmierczak
authors.affiliation: Department of Molecular and Cellular Pharmacology, University of Miami Miller School of Medicine, Miami, FL 33136;
authors.forename: Jingsheng
authors.initials: J
authors.lastname: Liang
authors.affiliation: Department of Molecular and Cellular Pharmacology, University of Miami Miller School of Medicine, Miami, FL 33136;
authors.forename: Wenrui
authors.initials: W
authors.lastname: Huang
authors.affiliation: Department of Biological, Chemical and Physical Sciences, Illinois Institute of Technology, Chicago, IL 60616.
authors.forename: Thomas C
authors.initials: TC
authors.lastname: Irving
authors.affiliation: Department of Molecular and Cellular Pharmacology, University of Miami Miller School of Medicine, Miami, FL 33136;
authors.forename: Rosemeire M
authors.initials: RM
authors.lastname: Kanashiro-Takeuchi
authors.affiliation: Department of Molecular and Cellular Pharmacology, University of Miami Miller School of Medicine, Miami, FL 33136;
authors.forename: Joshua M
authors.initials: JM
authors.lastname: Hare
authors.affiliation: Department of Molecular and Cellular Pharmacology, University of Miami Miller School of Medicine, Miami, FL 33136; DSzczesna@med.miami.edu.
authors.forename: Danuta
authors.initials: D
authors.lastname: Szczesna-Cordary
mesh_terms: D000818:Animals; D002118:Calcium / Q000737:chemistry; D002312:Cardiomyopathy, Hypertrophic / Q000378:metabolism*; D018360:Crystallography, X-Ray; D018450:Disease Progression; D004452:Echocardiography; D005260:Female; D006321:Heart / Q000503:physiopathology; D006439:Hemodynamics; D006801:Humans; D006984:Hypertrophy / Q000378:metabolism; D008297:Male; D051379:Mice; D008822:Mice, Transgenic; D009154:Mutation; D009200:Myocardial Contraction; D009210:Myofibrils / Q000378:metabolism; D018994:Myosin Light Chains / Q000737:chemistry* / Q000235:genetics*; D010641:Phenotype; D010766:Phosphorylation; D017433:Protein Structure, Secondary; D014961:X-Ray Diffraction
chemical_list: D018994:Myosin Light Chains; D002118:Calcium
keywords: X-ray structure; cardiomyopathy; hemodynamics; myocardial contraction; myosin RLC