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Title: Myoblast fusion in Drosophila

Abstract

The body wall musculature of a Drosophila larva is composed of an intricate pattern of 30 segmentally repeated muscle fibers in each abdominal hemisegment. Each muscle fiber has unique spatial and behavioral characteristics that include its location, orientation, epidermal attachment, size and pattern of innervation. Many, if not all, of these properties are dictated by founder cells, which determine the muscle pattern and seed the fusion process. Myofibers are then derived from fusion between a specific founder cell and several fusion competent myoblasts (FCMs) fusing with as few as 3-5 FCMs in the small muscles on the most ventral side of the embryo and as many as 30 FCMs in the larger muscles on the dorsal side of the embryo. The focus of the present review is the formation of the larval muscles in the developing embryo, summarizing the major issues and players in this process. We have attempted to emphasize experimentally-validated details of the mechanism of myoblast fusion and distinguish these from the theoretically possible details that have not yet been confirmed experimentally. We also direct the interested reader to other recent reviews that discuss myoblast fusion in Drosophila, each with their own perspective on the process . Withmore » apologies, we use gene nomenclature as specified by Flybase (http://flybase.org) but provide Table 1 with alternative names and references.« less

Authors:
 [1];  [1];  [2]
  1. Stowers Institute for Medical Research, Kansas City, MO 64110 (United States)
  2. (United States)
Publication Date:
OSTI Identifier:
22209914
Resource Type:
Journal Article
Resource Relation:
Journal Name: Experimental Cell Research; Journal Volume: 316; Journal Issue: 18; Other Information: Copyright (c) 2010 Elsevier Science B.V., Amsterdam, The Netherlands, All rights reserved.; Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
60 APPLIED LIFE SCIENCES; DROSOPHILA; EMBRYOS; GENES; LARVAE; MYOBLASTS; REVIEWS

Citation Formats

Haralalka, Shruti, Abmayr, Susan M., E-mail: sma@stowers.org, and Department of Anatomy and Cell Biology, University of Kansas Medical Center, Kansas City, MO 66160. Myoblast fusion in Drosophila. United States: N. p., 2010. Web. doi:10.1016/J.YEXCR.2010.05.018.
Haralalka, Shruti, Abmayr, Susan M., E-mail: sma@stowers.org, & Department of Anatomy and Cell Biology, University of Kansas Medical Center, Kansas City, MO 66160. Myoblast fusion in Drosophila. United States. doi:10.1016/J.YEXCR.2010.05.018.
Haralalka, Shruti, Abmayr, Susan M., E-mail: sma@stowers.org, and Department of Anatomy and Cell Biology, University of Kansas Medical Center, Kansas City, MO 66160. 2010. "Myoblast fusion in Drosophila". United States. doi:10.1016/J.YEXCR.2010.05.018.
@article{osti_22209914,
title = {Myoblast fusion in Drosophila},
author = {Haralalka, Shruti and Abmayr, Susan M., E-mail: sma@stowers.org and Department of Anatomy and Cell Biology, University of Kansas Medical Center, Kansas City, MO 66160},
abstractNote = {The body wall musculature of a Drosophila larva is composed of an intricate pattern of 30 segmentally repeated muscle fibers in each abdominal hemisegment. Each muscle fiber has unique spatial and behavioral characteristics that include its location, orientation, epidermal attachment, size and pattern of innervation. Many, if not all, of these properties are dictated by founder cells, which determine the muscle pattern and seed the fusion process. Myofibers are then derived from fusion between a specific founder cell and several fusion competent myoblasts (FCMs) fusing with as few as 3-5 FCMs in the small muscles on the most ventral side of the embryo and as many as 30 FCMs in the larger muscles on the dorsal side of the embryo. The focus of the present review is the formation of the larval muscles in the developing embryo, summarizing the major issues and players in this process. We have attempted to emphasize experimentally-validated details of the mechanism of myoblast fusion and distinguish these from the theoretically possible details that have not yet been confirmed experimentally. We also direct the interested reader to other recent reviews that discuss myoblast fusion in Drosophila, each with their own perspective on the process . With apologies, we use gene nomenclature as specified by Flybase (http://flybase.org) but provide Table 1 with alternative names and references.},
doi = {10.1016/J.YEXCR.2010.05.018},
journal = {Experimental Cell Research},
number = 18,
volume = 316,
place = {United States},
year = 2010,
month =
}
  • Besides representing the sarcomeric thick filaments, myosins are involved in many cellular transport and motility processes. Myosin heavy chains are grouped into 18 classes. Here we show that in Drosophila, the unconventional group XVIII myosin heavy chain-like (Mhcl) is transcribed in the mesoderm of embryos, most prominently in founder cells (FCs). An ectopically expressed GFP-tagged Mhcl localizes in the growing muscle at cell–cell contacts towards the attached fusion competent myoblast (FCM). We further show that Mhcl interacts in vitro with the essential fusion protein Rolling pebbles 7 (Rols7), which is part of a protein complex established at cell contact sitesmore » (Fusion-restricted Myogenic-Adhesive Structure or FuRMAS). Here, branched F-actin is likely needed to widen the fusion pore and to integrate the myoblast into the growing muscle. We show that the localization of Mhcl is dependent on the presence of Rols7, and we postulate that Mhcl acts at the FuRMAS as an actin motor protein. We further show that Mhcl deficient embryos develop a wild-type musculature. We thus propose that Mhcl functions redundantly to other myosin heavy chains in myoblasts. Lastly, we found that the protein is detectable adjacent to the sarcomeric Z-discs, suggesting an additional function in mature muscles. - Highlights: ► The class XVIII myosin encoding gene Mhcl is transcribed in the mesoderm. ► Mhcl localization at contact sites of fusing myoblasts depends on Rols7. ► Mhcl interacts in vitro with Rols7 which is essential for myogenesis. ► Functional redundancy with other myosins is likely as mutants show no muscle defects. ► Mhcl localizes adjacent to Z-discs of sarcomeres and might support muscle integrity.« less
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