title: Adding a new dimension to cardiac nano-architecture using electron microscopy: coupling membrane excitation to calcium signaling.
abstract: Advances in microscopic imaging technologies and associated computational methods now allow descriptions of cellular anatomy to go beyond 2-dimensions, revealing new micro-domain dynamics at unprecedented resolutions. In cardiomyocytes, electron microscopy (EM) first described junctional membrane complexes between the sarcolemma and sarcoplasmic reticulum over a half-century ago. Since then, 3-dimensional EM technologies such as electron tomography have become successful in determining the realistic nano-geometry of membrane junctions (dyads and peripheral junctions) and associated structures such as transverse tubules (T-tubules, aka. T-system). Concomitantly, super-resolution light microscopy has gone beyond the diffraction-limit to determine the distribution of molecules, such as ryanodine receptors, with 10(-8) meter (10nm) order accuracy. This review provides the current structural perspective and functional interpretation of membrane junction complexes, which are the central machinery controlling cardiac excitation-contraction coupling via calcium signaling.
authors.affiliation: The Center for Research in Biological Systems, University of California San Diego, La Jolla, CA 92093, USA.
authors.forename: Tapaswini
authors.initials: T
authors.lastname: Das
authors.forename: Masahiko
authors.initials: M
authors.lastname: Hoshijima
mesh_terms: D020013:Calcium Signaling; D006801:Humans; D007365:Intercellular Junctions / Q000648:ultrastructure; D008566:Membranes / Q000648:ultrastructure; D008854:Microscopy, Electron; D009119:Muscle Contraction / Q000502:physiology; D009206:Myocardium / Q000648:ultrastructure*; D032383:Myocytes, Cardiac / Q000648:ultrastructure*; D012508:Sarcolemma / Q000648:ultrastructure; D012519:Sarcoplasmic Reticulum / Q000648:ultrastructure