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(Circulation Research. 2006;99:225.)
© 2006 American Heart Association, Inc.

Editorials

Myosin Light Chain 2 Into the Mainstream of Cardiac Development and Contractility

Richard L. Moss, Daniel P. Fitzsimons

From the Department of Physiology, University of Wisconsin School of Medicine and Public Health, Madison.

Correspondence to Dr Richard L. Moss, Department of Physiology, University of Wisconsin Medical School, 1300 University Ave, Madison, WI 53706. E-mail rlmoss@physiology.wisc.edu

See related article, pages 323–331

Key Words: myosin light chain 2 • thick filament • development

An extract of the first 250 words of the full text is provided, because this article has no abstract.

	Introduction

 
Myocardium exhibits a remarkably broad dynamic range of function that is normally well matched to the circulatory load on the heart. Regulation of cardiac contraction is a multifaceted process that is well understood in terms of the activating role of Ca²⁺ but much less well in terms of modulation by thick filament accessory proteins and by post-translational modification of thick and thin filament proteins.^1,2 In this issue of Circulation Research, an elegant study by Fishman and colleagues³ dramatically reinforces the idea that the light chain 2 subunit of myosin (MLC-2) is critically important in myocardium by showing that MLC-2 loss because of mutation abolishes myofibrillar assembly in zebrafish, resulting in embryonic lethality. Earlier work had shown that mutations in MLC-2 account for some cases of hypertrophic cardiomyopathy⁴ and that phosphorylation of MLC-2 contributes to cardiac pump function,⁵ but now it is evident that MLC-2 has an obligatory role in development.

Cardiac isoforms of myosin II comprise the motor of myocardial contraction and like all members of this family are composed of 6 subunits⁶: 2 myosin heavy chains of &200 kDa molecular weight, 2 so-called essential light chains (or light chain 1) of &17 kDa, and 2 regulatory light chains (or light chain 2) of >20 kDa. Subfragment 1 of the heavy chain (Figure) comprises the business end of the motor, containing both the nucleotide and actin-binding sites, whereas the light chains wrap around the rod-like extension of subfragment 1 and are believed to function (minimally) as . . . [Full Text of this Article]

Related Article:

Cardiac Myosin Light Chain-2: A Novel Essential Component of Thick-Myofilament Assembly and Contractility of the Heart

Wolfgang Rottbauer, Georgia Wessels, Tillman Dahme, Steffen Just, Nicole Trano, David Hassel, Charles Geoffrey Burns, Hugo A. Katus, and Mark C. Fishman
Circ. Res. 2006 99: 323-331. [Abstract] [Full Text] [PDF]

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