title: A myosin activator improves actin assembly and sarcomere function of human-induced pluripotent stem cell-derived cardiomyocytes with a troponin T point mutation.
abstract: We have investigated cardiac myocytes derived from human-induced pluripotent stem cells (iPSC-CMs) from two normal control and two family members expressing a mutant cardiac troponin T (cTnT-R173W) linked to dilated cardiomyopathy (DCM). cTnT is a regulatory protein of the sarcomeric thin filament. The loss of this basic charge, which is strategically located to control tension, has consequences leading to progressive DCM. iPSC-CMs serve as a valuable platform for understanding clinically relevant mutations in sarcomeric proteins; however, there are important questions to be addressed with regard to myocyte adaptation that we model here by plating iPSC-CMs on softer substrates (100 kPa) to create a more physiologic environment during recovery and maturation of iPSC-CMs after thawing from cryopreservation. During the first week of culture of the iPSC-CMs, we have determined structural and functional characteristics as well as actin assembly dynamics. Shortening, actin content, and actin assembly dynamics were depressed in CMs from the severely affected mutant at 1 wk of culture, but by 2 wk differences were less apparent. Sarcomeric troponin and myosin isoform composition were fetal/neonatal. Furthermore, the troponin complex, reconstituted with wild-type cTnT or recombinant cTnT-R173W, depressed the entry of cross-bridges into the force-generating state, which can be reversed by the myosin activator omecamtiv mecarbil. Therapeutic doses of this drug increased both contractility and the content of F-actin in the mutant iPSC-CMs. Collectively, our data suggest the use of a myosin activation reagent to restore function within patient-specific iPSC-CMs may aid in understanding and treating this familial DCM.
authors.affiliation: Department of Bioengineering, University of Illinois at Chicago, Chicago, Illinois;
authors.forename: K M
authors.initials: KM
authors.lastname: Broughton
authors.affiliation: Department of Physiology and Biophysics, University of Illinois at Chicago, Chicago, Illinois; and.
authors.forename: J
authors.initials: J
authors.lastname: Li
authors.affiliation: Department of Bioengineering, University of Illinois at Chicago, Chicago, Illinois;
authors.forename: E
authors.initials: E
authors.lastname: Sarmah
authors.affiliation: Department of Physiology and Biophysics, University of Illinois at Chicago, Chicago, Illinois; and.
authors.forename: C M
authors.initials: CM
authors.lastname: Warren
authors.affiliation: Department of Physiology and Biophysics, University of Illinois at Chicago, Chicago, Illinois; and.
authors.forename: Y-H
authors.initials: YH
authors.lastname: Lin
authors.affiliation: Department of Physiology and Biophysics, University of Illinois at Chicago, Chicago, Illinois; and.
authors.forename: M P
authors.initials: MP
authors.lastname: Henze
authors.affiliation: Department of Medicine, Division of Cardiology, Stanford University School of Medicine, Stanford, California.
authors.forename: V
authors.initials: V
authors.lastname: Sanchez-Freire
authors.affiliation: Department of Physiology and Biophysics, University of Illinois at Chicago, Chicago, Illinois; and.
authors.forename: R J
authors.initials: RJ
authors.lastname: Solaro
authors.affiliation: Department of Physiology and Biophysics, University of Illinois at Chicago, Chicago, Illinois; and russell@uic.edu.
authors.forename: B
authors.initials: B
authors.lastname: Russell
mesh_terms: D000199:Actins / Q000378:metabolism*; D000818:Animals; D000831:Animals, Newborn; D024722:Cardiac Myosins / Q000378:metabolism*; D002316:Cardiotonic Agents / Q000494:pharmacology*; D002460:Cell Line; D004305:Dose-Response Relationship, Drug; D004789:Enzyme Activation; D020536:Enzyme Activators / Q000494:pharmacology*; D005838:Genotype; D006801:Humans; D057026:Induced Pluripotent Stem Cells / Q000187:drug effects* / Q000201:enzymology; D009200:Myocardial Contraction / Q000187:drug effects*; D032383:Myocytes, Cardiac / Q000187:drug effects* / Q000201:enzymology; D010641:Phenotype; D017354:Point Mutation; D017207:Rats, Sprague-Dawley; D012518:Sarcomeres / Q000187:drug effects* / Q000201:enzymology; D013997:Time Factors; D020107:Troponin T / Q000235:genetics* / Q000378:metabolism; D014508:Urea / Q000031:analogs & derivatives* / Q000494:pharmacology
chemical_list: D000199:Actins; D002316:Cardiotonic Agents; D020536:Enzyme Activators; C545568:TNNT2 protein, human; D020107:Troponin T; C547293:omecamtiv mecarbil; D014508:Urea; D024722:Cardiac Myosins
keywords: contractility; heart failure; myocytes; stem cells