Myosin filaments in smooth muscle cells do not have a constant length.

TitleMyosin filaments in smooth muscle cells do not have a constant length.
Publication TypeJournal Article
Year of Publication2013
AuthorsLiu, JC-Y, Rottler, J, Wang, L, Zhang, J, Pascoe, CD, Lan, B, Norris, BA, Herrera, AM, Paré, PD, Seow, CY
JournalJ Physiol
Volume591
IssuePt 23
Pagination5867-78
Date Published2013 Dec 1
ISSN1469-7793
KeywordsAnimals, Carotid Arteries, Diaphragm, Mice, Mice, Inbred C57BL, Microscopy, Electron, Myocytes, Smooth Muscle, Myosins, Pulmonary Artery, Rabbits, Sheep, Trachea
Abstract

Myosin molecules from smooth muscle and non-muscle cells are known to self-assemble into side-polar filaments in vitro. However, the in situ mechanism of filament assembly is not clear and the question of whether there is a unique length for myosin filaments in smooth muscle is still under debate. In this study we measured the lengths of 16,587 myosin filaments in three types of smooth muscle cells using serial electron microscopy (EM). Sheep airway and pulmonary arterial smooth muscle as well as rabbit carotid arterial smooth muscle were fixed for EM and serial ultra-thin (50-60 nm) sections were obtained. Myosin filaments were traced in consecutive sections to determine their lengths. The results indicate that there is not a single length for the myosin filaments; instead there is a wide variation in lengths. The plots of observation frequency versus myosin filament length follow an exponential decay pattern. Analysis suggests that in situ assembly of myosin filaments in smooth muscle is governed by random processes of linear polymerization and de-polymerization, and that the dynamic equilibrium of these processes determines the observed length distribution.

DOI10.1113/jphysiol.2013.264168
Alternate JournalJ. Physiol. (Lond.)
PubMed ID24081161
PubMed Central IDPMC3872758
Grant ListMOP-13271 / / Canadian Institutes of Health Research / Canada
MOP-37924 / / Canadian Institutes of Health Research / Canada