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Minigenes encoding N-terminal domains of human cardiac myosin light chain-1 improve heart function of transgenic rats

Item Type:Article
Title:Minigenes encoding N-terminal domains of human cardiac myosin light chain-1 improve heart function of transgenic rats
Creators Name:Haase, H., Dobbernack, G., Tünnemann, G., Karczewski, P., Cardoso, C., Petzhold, D., Schlegel, W.P., Lutter, S., Pierschalek, P., Behlke, J. and Morano, I.
Abstract:In this study we investigated whether the expression of N-terminal myosin light chain-1 (MLC-1) peptides could improve the intrinsic contractility of the whole heart. We generated transgenic rats (TGR) that overexpressed minigenes encoding the N-terminal 15 amino acids of human atrial MLC-1 (TGR/hALC-1/1-15, lines 7475 and 3966) or human ventricular MLC-1 (TGR/hVLC-1/1-15, lines 6113 and 6114) isoforms in cardiomyocytes. Synthetic N-terminal peptides revealed specific actin binding, with a significantly (P<0.01) lower dissociation constant (K(D)) for the hVLC-1/1-15-actin complex compared with the K(D) value of the hALC-1/1-15-actin complex. Using synthetic hVLC-1/1-15 as a TAT fusion peptide labeled with the fluorochrome TAMRA, we observed specific accumulation of the N-terminal MLC-1 peptide at the sarcomere predominantly within the actin-containing I-band, but also within the actin-myosin overlap zone (A-band) in intact adult cardiomyocytes. For the first time we show that the expression of N-terminal human MLC-1 peptides in TGR (range: 3-6 muM) correlated positively with significant (P<0.001) improvements of the intrinsic contractile state of the isolated perfused heart (Langendorff mode): systolic force generation, as well as the rates of both force generation and relaxation, rose in TGR lines that expressed the transgenic human MLC-1 peptide, but not in a TGR line with undetectable transgene expression levels. The positive inotropic effect of MLC-1 peptides occurred in the absence of a hypertrophic response. Thus, expression of N-terminal domains of MLC-1 represent a valuable tool for the treatment of the failing heart.
Keywords:Myosin Light Chain, Actin, Heart, Contractility, Animals, Rats
Source:FASEB Journal
Publisher:Federation of American Societies for Experimental Biology
Page Range:865-873
Date:May 2006
Official Publication:https://doi.org/10.1096/fj.05-5414com
PubMed:View item in PubMed

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