Myogenesis: A View from Drosophila

Memorial Sloan-Kettering Cancer Center, Sloan Kettering Division, Graduate School of Medical Sciences, Cornell University, New York, New York 10021, USA.
Cell (Impact Factor: 32.24). 07/1998; 93(6):921-7. DOI: 10.1016/S0092-8674(00)81198-8
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Available from: Mary Baylies, Aug 28, 2015
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    • "Given the complexity of the Drosophila larval muscle pattern, myoblast fusion is a highly regulated process (reviewed in (Abmayr and Pavlath, 2012)). Characterization of selected muscle lineages has established that muscle identity -orientation, shape, size/number of nuclei, epidermal attachment sites characteristic of each muscle -, reflects the expression and function in each PC and FC of a specific combination of muscle identity transcription factors (iTFs) (Baylies et al., 1998; de Joussineau et al., 2012; Enriquez et al., 2012; Frasch, 1999). The A2-A7 segments present roughly the same pattern of body wall muscles. "
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    ABSTRACT: The body plan of arthropods and vertebrates involves the formation of repetitive segments, which subsequently diversify to give rise to different body parts along the antero-posterior/rostro-caudal body axis. Anatomical variations between body segments are crucial for organ function and organismal fitness. Pioneering work in Drosophila has established that Hox transcription factors play key roles both in endowing initially identical segments with distinct identities and organogenesis. The focus of this review is on Alary Muscles (AMs) and the newly discovered Thoracic Alary-Related Muscles (TARMs). AMs and TARMs are thin muscles which together connect the circulatory system and different midgut regions to the exoskeleton, while intertwining with the respiratory tubular network. They were hypothesized to represent a new type of muscles with spring-like properties, maintaining internal organs in proper anatomical positions during larval locomotion. Both the morphology of TARMs relative to AMs, and morphogenesis of connected tissues is under Hox control, emphasizing the key role of Hox proteins in coordinating the anatomical development of the larva. Copyright © 2015. Published by Elsevier Ireland Ltd.
    Mechanisms of development 07/2015; DOI:10.1016/j.mod.2015.07.005 · 2.44 Impact Factor
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    • "FCs are born from the asymmetric division of progenitor cells (PCs) specified at precise positions and times within the somatic mesoderm. Detailed characterization of a few somatic muscle lineages has established that muscle identity (specific shape, size, orientation) reflects the expression of specific muscle identity transcription factors (iTFs) in each FC that act in a combinatorial manner (Baylies et al., 1998; Frasch, 1999; de Joussineau et al., 2012; Enriquez et al., 2012). "
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    ABSTRACT: The T-box transcription factor Tbx1 and the LIM-homeodomain transcription factor Islet1 are key components in regulatory circuits that generate myogenic and cardiogenic lineage diversity in chordates. We show here that Org-1 and Tup, the Drosophila orthologs of Tbx1 and Islet1, are co-expressed and required for formation of the heart-associated alary muscles (AMs) in the abdomen. The same holds true for lineage-related muscles in the thorax that have not been described previously, which we name thoracic alary-related muscles (TARMs). Lineage analyses identified the progenitor cell for each AM and TARM. Three-dimensional high-resolution analyses indicate that AMs and TARMs connect the exoskeleton to the aorta/heart and to different regions of the midgut, respectively, and surround-specific tracheal branches, pointing to an architectural role in the internal anatomy of the larva. Org-1 controls tup expression in the AM/TARM lineage by direct binding to two regulatory sites within an AM/TARM-specific cis-regulatory module, tupAME. The contributions of Org-1 and Tup to the specification of Drosophila AMs and TARMs provide new insights into the transcriptional control of Drosophila larval muscle diversification and highlight new parallels with gene regulatory networks involved in the specification of cardiopharyngeal mesodermal derivatives in chordates.
    Development 10/2014; 141(19):3761-3771. DOI:10.1242/dev.111005 · 6.46 Impact Factor
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    • "Two waves of myogenesis have been described in Drosophila: the first occurs during embryogenesis to give rise to the larval muscles (for review, see [3], [4]), the second takes place during pupariation and leads to the adult muscles (for review, see [4]). A particular set of adult muscle structures, the Indirect Flight Muscles (IFMs) provide a valuable tissue context to study muscle development. "
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    ABSTRACT: Myogenesis of indirect flight muscles (IFMs) in Drosophila melanogaster follows a well-defined cellular developmental scheme. During embryogenesis, a set of cells, the Adult Muscle Precursors (AMPs), are specified. These cells will become proliferating myoblasts during the larval stages which will then give rise to the adult IFMs. Although the cellular aspect of this developmental process is well studied, the molecular biology behind the different stages is still under investigation. In particular, the interactions required during the transition from proliferating myoblasts to differentiated myoblasts ready to fuse to the muscle fiber. It has been previously shown that the Notch pathway is active in proliferating myoblasts, and that this pathway is inhibited in developing muscle fibers. Furthermore, the Myocyte Enhancing Factor 2 (Mef2), Vestigial (Vg) and Scalloped (Sd) transcription factors are necessary for IFM development and that Vg is required for Notch pathway repression in differentiating fibers. Here we examine the interactions between Notch and Mef2 and mechanisms by which the Notch pathway is inhibited during differentiation. We show that Mef2 is capable of inhibiting the Notch pathway in non myogenic cells. A previous screen for Mef2 potential targets identified Delta a component of the Notch pathway. Dl is expressed in Mef2 and Sd-positive developing fibers. Our results show that Mef2 and possibly Sd regulate a Dl enhancer specifically expressed in the developing IFMs and that Mef2 is required for Dl expression in developing IFMs.
    PLoS ONE 09/2014; 9(9):e108149. DOI:10.1371/journal.pone.0108149 · 3.23 Impact Factor
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