Transgenic Remodeling of the Regulatory Myosin Light Chains in the Mammalian Heart
| Autor: | Timothy E. Hewett, Raisa Klevitsky, Scott H. Buck, Jeffrey Robbins, Richard L. Moss, James Gulick |
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| Rok vydání: | 1997 |
| Předmět: |
Electrophoresis
Protein isoform Gene isoform Heterozygote medicine.medical_specialty Myosin Light Chains Myosin light-chain kinase Physiology Heart Ventricles Transgene Molecular Sequence Data Muscle Proteins Mice Transgenic Biology Polymerase Chain Reaction Mice Internal medicine Myosin medicine Animals Myocyte Heart Atria Transgenes Muscle Skeletal Base Sequence Myocardium Genetic Variation Heart Myocardial Contraction Cell biology Endocrinology MYH7 MYH6 Cardiology and Cardiovascular Medicine |
| Zdroj: | Circulation Research. 80:655-664 |
| ISSN: | 1524-4571 0009-7330 |
| DOI: | 10.1161/01.res.80.5.655 |
| Popis: | Abstract The regulatory myosin light chain (MLC) regulates contraction in smooth muscle. However, its function in striated muscle remains obscure, and the different functional activities of the various isoforms that are expressed in the mammalian heart (ventricle- and atrium-specific MLC2) remain undefined. To begin to explore these issues, we used transgenesis to determine the feasibility of effecting a complete or partial replacement of the cardiac regulatory light chains with the isoform that is normally expressed in fast skeletal muscle fibers (fast muscle–specific MLC2). Multiple lines of transgenic mice were generated that expressed the transgene at varying levels in the heart in a copy number–dependent fashion. There is a major discordance in the manner in which the different cardiac compartments respond to high levels of overexpression of the transgene. In atria, isoform replacement with the skeletal protein was quite efficient, even at low copy number. The ventricle is much more refractory to replacement, and despite high levels of transgenic transcript, protein replacement was incomplete. Replacement could be further increased by breeding the transgenic lines with one another. Despite very high levels of transgenic transcript in these mice, the overall level of the regulatory light chain in both compartments remained essentially constant; only the protein isoform ratios were altered. The partial replacement of the ventricular with the skeletal isoform reduced both left ventricular contractility and relaxation, although the unloaded shortening velocity of isolated ventricular cardiomyocytes was not significantly different. |
| Databáze: | OpenAIRE |
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