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          Institute: MPI für Entwicklungsbiologie     Collection: Abteilungsunabhängige Arbeitsgruppen     Display Documents



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ID: 332613.0, MPI für Entwicklungsbiologie / Abteilungsunabhängige Arbeitsgruppen
Drosophila MICAL regulates myofilament organization and synaptic structure.
Authors:Beuchle, Dirk; Schwarz, Heinz; Langegger, Maria; Koch, Iris; Aberle, Hermann
Language:English
Date of Publication (YYYY-MM-DD):2007-05
Title of Journal:Mech Dev.
Volume:124
Issue / Number:5
Start Page:390
End Page:406
Sequence Number of Article:17350233
Review Status:not specified
Audience:Not Specified
Abstract / Description:The overall size and structure of a synaptic terminal is an important determinant of its function. In a large-scale mutagenesis screen, designed to identify Drosophila mutants with abnormally structured neuromuscular junctions (NMJs), we discovered mutations in Drosophila mical, a conserved gene encoding a multi-domain protein with a N-terminal monooxygenase domain. In mical mutants, synaptic boutons do not sprout normally over the muscle surface and tend to form clusters along synaptic branches and at nerve entry sites. Consistent with high expression of MICAL in somatic muscles, immunohistochemical stainings reveal that the subcellular localization and architecture of contractile muscle filaments are dramatically disturbed in mical mutants. Instead of being integrated into a regular sarcomeric pattern, actin and myosin filaments are disorganized and accumulate beneath the plasmamembrane. Whereas contractile elements are strongly deranged, the proposed organizer of sarcomeric structure, D-Titin, is much less affected. Transgenic expression of interfering RNA molecules demonstrates that MICAL is required in muscles for the higher order arrangement of myofilaments. Ultrastructural analysis confirms that myosin-rich thick filaments enter submembranous regions and interfere with synaptic development, indicating that the disorganized myofilaments may cause the synaptic growth phenotype. As a model, we suggest that the filamentous network around synaptic boutons restrains the spreading of synaptic branches.
External Publication Status:published
Document Type:Article
Affiliations:MPI für Entwicklungsbiologie/Abteilung 3 - Genetik (Christiane Nüsslein-Volhard)
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