Cytoskeletal Components during Myogenesis of Drosophila melanogaster: Microtubules vs. Myosins as Actin Motor Proteins
Rudolf, Anja
The syncytial larval musculature of Drosophila melanogaster develops during embryogenesis by fusion of two different cell types, the founder cells (FCs), which determine the identity of an individual muscle, and the fusion competent myoblasts (FCMs). During the fusion events in the somatic mesoderm, which gives rise to the body wall muscles, a Fusion-restricted Myogenic-Adhesive Structure (FuRMAS) is established, consisting of a ring of adhesion molecules and their adaptor proteins as well as of an actin-rich plug on the side of the FCM and an actin sheet on the side of the FC. This FuRMAS is supposed to act as a signaling center, linking cell adhesion to downstream fusion steps.
The actin cytoskeleton is supposed to be important in processes like vesicle transport, fusion pore expansion and force generation at the FuRMAS. This thesis provides analyses of transport processes via microtubules during myogenesis by analyzing the expression of -Tubulin isoforms, as the structural subunits of microtubules. Although strongly expressed in the mesoderm, the somatic and visceral musculature develops independently of the 3-Tubulin isoform. Furthermore, a low level of maternally supplied 1-Tubulin is sufficient for body wall muscle formation. Thus, it is concluded that newly synthesized microtubules and microtubule-based transport processes are less important for Drosophila myogenesis.
Rolling pebbles 7 (Rols7) is an essential adaptor protein at the FuRMAS on the side of the FCs, which interacts in vitro with Myosin heavy chain-like (Mhcl). In this thesis, it is shown that Mhcl is also expressed in FCs, and localizes at the contact sites towards the adhering FCM. This unconventional myosin might act as a motor protein for F-actin at the FuRMAS, being involved in vesicle transport or widening of the fusion pore, most likely redundantly to other myosin heavy chains.
The syncytial visceral muscles of the embryo surround the gut as a network of binucleated circular muscles and perpendicularly arranged multinucleated longitudinal muscles. The longitudinal FCs migrate from the caudal visceral mesoderm and are shown in this thesis to fuse with a different FCM type than the circular FCs do. Furthermore, Rols7 is needed during myoblast fusion giving rise to the longitudinal gut muscles, while proteins regulating actin polymerization are involved either already in migration of the longitudinal FCs or also in the fusion processes itself. In conclusion, this muscle type develops distinct to the circular gut muscles and the body wall musculature of Drosophila.
Philipps-Universität Marburg
Life sciences
urn:nbn:de:hebis:04-z2012-09601
https://doi.org/10.17192/z2012.0960
opus:4591
2012-11-16
Drosophila
urn:nbn:de:hebis:04-z2012-09601
monograph
Taufliege
https://archiv.ub.uni-marburg.de/diss/z2012/0960/cover.png
Rudolf, Anja
Rudolf
Anja
2012-12-07
The syncytial larval musculature of Drosophila melanogaster develops during embryogenesis by fusion of two different cell types, the founder cells (FCs), which determine the identity of an individual muscle, and the fusion competent myoblasts (FCMs). During the fusion events in the somatic mesoderm, which gives rise to the body wall muscles, a Fusion-restricted Myogenic-Adhesive Structure (FuRMAS) is established, consisting of a ring of adhesion molecules and their adaptor proteins as well as of an actin-rich plug on the side of the FCM and an actin sheet on the side of the FC. This FuRMAS is supposed to act as a signaling center, linking cell adhesion to downstream fusion steps.
The actin cytoskeleton is supposed to be important in processes like vesicle transport, fusion pore expansion and force generation at the FuRMAS. This thesis provides analyses of transport processes via microtubules during myogenesis by analyzing the expression of -Tubulin isoforms, as the structural subunits of microtubules. Although strongly expressed in the mesoderm, the somatic and visceral musculature develops independently of the 3-Tubulin isoform. Furthermore, a low level of maternally supplied 1-Tubulin is sufficient for body wall muscle formation. Thus, it is concluded that newly synthesized microtubules and microtubule-based transport processes are less important for Drosophila myogenesis.
Rolling pebbles 7 (Rols7) is an essential adaptor protein at the FuRMAS on the side of the FCs, which interacts in vitro with Myosin heavy chain-like (Mhcl). In this thesis, it is shown that Mhcl is also expressed in FCs, and localizes at the contact sites towards the adhering FCM. This unconventional myosin might act as a motor protein for F-actin at the FuRMAS, being involved in vesicle transport or widening of the fusion pore, most likely redundantly to other myosin heavy chains.
The syncytial visceral muscles of the embryo surround the gut as a network of binucleated circular muscles and perpendicularly arranged multinucleated longitudinal muscles. The longitudinal FCs migrate from the caudal visceral mesoderm and are shown in this thesis to fuse with a different FCM type than the circular FCs do. Furthermore, Rols7 is needed during myoblast fusion giving rise to the longitudinal gut muscles, while proteins regulating actin polymerization are involved either already in migration of the longitudinal FCs or also in the fusion processes itself. In conclusion, this muscle type develops distinct to the circular gut muscles and the body wall musculature of Drosophila.
Muskelentwicklung
2012
Philipps-Universität Marburg
https://doi.org/10.17192/z2012.0960
ths
Prof. Dr.
Renkawitz-Pohl
Renate
Renkawitz-Pohl, Renate (Prof. Dr.)
Publikationsserver der Universitätsbibliothek Marburg
Universitätsbibliothek Marburg
Cytoskeletal Components during Myogenesis of Drosophila melanogaster: Microtubules vs. Myosins as Actin Motor Proteins
Biologie
Fachbereich Biologie
2012-12-07
English
Life sciences
Biowissenschaften, Biologie
opus:4591
Myogenesis
Zytoskelett-Komponenten während der Myogenese von Drosophila melanogaster: Mikrotubuli sowie Myosine als Aktin-Motorporteine
Die synzytiale larvale Muskulatur von Drosophila melanogaster entsteht, indem zwei unterschiedliche Zelltypen miteinander fusionieren, die Identität-vermittelnden Founder Zellen (FCs) mit Fusions-kompetenten Myoblasten (FCMs). Während der Fusion im somatischen Mesoderm wird ein Signalkomplex etabliert, der als Fusion-restricted Myogenic-Adhesive Structure (FuRMAS) bezeichnet wird, bestehend aus einem Ring von Adhäsionsmolekülen sowie einem Aktin-reichen Fokus auf Seiten der FCM und einer Aktin-Schicht auf Seiten der FC. Dieser Signalkomplex verknüpft die Zelladhäsion mit nachfolgenden Fusionsschritten.
Das Aktin-Zytoskelett nimmt während der Myoblastenfusion wahrscheinlich wichtige Funktionen ein, z.B. den Transport von Vesikeln, der Expansion der Fusionspore sowie die Generierung von Kraft, um die FCM in den wachsenden Muskel zu integrieren. In dieser Arbeit wird untersucht, ob zusätzlich zum Aktin-Zytoskelett Transportprozesse über Mikrotubuli involviert sind, indem die Expression von -Tubulinen, den strukturellen Untereinheiten der Mikrotubuli, analysiert wird. Trotz der starken Expression im Mesoderm entwickelt sich die embryonale Muskulatur unabhängig von der 3-Tubulin Isoform. Desweiteren sind geringe Mengen des maternal bereitgestellten 1-Tubulin ausreichend für die Entwicklung der Körperwandmuskulatur, sodass Mikrotubuli-basierte Transportprozesse während der Drosophila Myogenese eine untergeordnete Rolle zu spielen scheinen.
Rolling pebbles 7 (Rols7) stellt ein essentielles Adaptor-Protein an den FuRMAS auf Seiten der FC dar, welches in vitro mit Myosin heavy chain-like (Mhcl) interagiert. In dieser Arbeit wird gezeigt, dass Mhcl ebenfalls in FCs exprimiert wird und an der Kontaktstelle hin zur adhärierenden FCM lokalisiert. Dieses unkonventionelle Myosin könnte als Aktin-Motorprotein an den FuRMAS agieren und am Transport von Vesikeln oder dem Weiten der Fusionspore beteiligt sein, wahrscheinlich in Redundanz zu anderen Myosinen.
Die synzytiale viszerale Muskulatur im Embryo umgibt den Darm als Netzwerk aus binukleären zirkulären Muskeln und multinukleären longitudinalen Muskeln. Diese Arbeit zeigt, dass die longitudinalen FCs mit einem anderen FCM-Typ als die zirkulären FCs fusionieren. Das Adapter-Protein Rols7 ist an diesem Fusionsprozess beteiligt, während Proteine, die die Aktin-Polymerisierung während des somatischen Fusionsprozesses regulieren, bereits in der Wanderung der longitudinalen FCs oder ebenfalls in der Entstehung von Synzytien involviert sind.
doctoralThesis
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