A Calcium Signaling Cascade Essential for Myosin Thick Filament Assembly in Xenopus Myocytes |
| |
Authors: | Michael B Ferrari Katharina Ribbeck Donald J Hagler Jr and Nicholas C Spitzer |
| |
Institution: | Department of Biology and Center for Molecular Genetics, University of California San Diego, La Jolla, California 92093-0357 |
| |
Abstract: | Spontaneous calcium release from intracellular stores occurs during myofibrillogenesis, the process of sarcomeric protein assembly in striated muscle. Preventing these Ca2+ transients disrupts sarcomere formation, but the signal transduction cascade has not been identified. Here we report that specific blockade of Ca2+ release from the ryanodine receptor (RyR) activated Ca2+ store blocks transients and disrupts myosin thick filament (A band) assembly. Inhibition of an embryonic Ca2+/calmodulin-dependent myosin light chain kinase (MLCK) by blocking the ATP-binding site, by allosteric phosphorylation, or by intracellular delivery of a pseudosubstrate peptide, also disrupts sarcomeric organization. The results indicate that both RyRs and MLCK, which have well-described calcium signaling roles in mature muscle contraction, have essential developmental roles during construction of the contractile apparatus. |
| |
Keywords: | |
|
|