Substrate regulation of structural order and beating strain dynamics of single cardiomyocytes
Recent experiments [1] show that both striation, an indication of the structural registry in muscle fibers, as well as the contractile strains produced by beating cardiac muscle cells, can be optimized by substrate stiffness. We show theoretically how the substrate rigidity dependence of the registry data can be mapped onto that of the strain measurements. We determine [2] the elasticity-mediated structural registry including both the elastic interactions of neighboring, actively contractile acto-myosin units as well as the noise inherent in biological systems. By assuming that structurally registered myofibrils also tend to beat in phase, we explain the observed dependence of both structural striation and beating strain measurements of heart muscle cells on substrate stiffness in a unified manner. The agreement of our ideas with experiment suggests that the correlated beating of heart cells may be limited by the structural registry of the myofibrils which in turn is regulated by their elastic environment. We also present new theoretical predictions focus on the role of the substrate and the intercellular distance in the synchronization of the beating of cellular assemblies.
[1] S. Majkut et al., Current Biology, 23, 2323 (2013).
[2] K. Dasbiswas, S. Majkut, D. Discher and S. Safran, Nature Comm., 6, 7085 (2015).
Collaborations: Theory – Kinjal Dasbiswas, Ohad Cohen (Weizmann Institute of Science); Experiment – Dennis Discher, Stephanie Majkut (Penn)
Bio
Prof. Samuel Safran is a physicist who works with chemists, biologists and other physicists to understand the structure and organization of soft matter and biomaterials. He joined the Weizmann Institute in 1990 as a professor in the Department of Materials and Interfaces, served as Dean of the Feinberg Graduate School for six years, beginning in 1995, and was appointed Vice President of the Institute in December 2001. He is the author of a widely noted graduate-level textbook on the physics of interfaces and membranes (recently translated into Japanese) and has also edited and contributed to numerous other volumes. He was elected a Fellow of the American Physical Society and is a member of the American Chemical Society, the Materials Research Society and the European Physical Society. He is the first incumbent of the Fern and Manfred Steinfeld Professorial Chair.