Die Analyse der cis-Regulation des rols-Gens und die Beteiligung von Rols7 am Aufbau eines podosomen-ähnlichen adhäsiven Komplexes (PILMAC), der eine zentrale Rolle in der Myoblastenfusion bei Drosophila melanogaster einnimmt. - 2., korr. Aufl.

The rolling pebbles gene is one of the essential genes for myoblast fusion in Drosophila melanogaster. The initiation of transcription and the tissue-specific expression is regulated by an unusual promoter without known core-promoter elements and with a cytosin as transcriptional start site (TSS). For the time- and tissue-specific expression of rols7 256 bp are sufficient, from which 19 bp are localized 5’ of the TSS and 237 bp 3’ of the TSS. A regulatory element involved in the modulation of the expression level is localized at the position 875-1392 bp 5’ of the TSS. The enhancer needed for the expression of rols7 in the visceral mesoderm is a part of the first intron. The analysis of the Drosophila pseudoobscura rols-gene reveals the conservation of the protein, the expression pattern and the transcriptional regulation. The conservation of the gene-regulation was verified for rols6 and rols7 by the analysis of the expression of a lacZ-reportergene in transgenic Drosophila melanogaster embryos. The conservation of the rols6-regulation shows that the functional conservation of the cis-regulators is independent of the sequence conservation of the regulators. This is maybe due to a coevolution of cis- and transregulatory elements. The contribution of known myogenesis-relevant transcription factors to the regulation of rols7 could be excluded. The translation initation factor eIF3-S10 was identified in a binding site screen due to the binding ability of the protein to the region of the rols7 leader. This factor could be relevant for processes like the transport and the localization of the rols7 mRNA and the translation control of the rols7 transcript, as the rols7 transcript is localized and eIF3-S10 is expressed in the mesoderm when myogenesis takes place. The analysis of the protein localization of Rols7, Duf and Sns in the mesoderm of wildtype and mutant embryos shows that these proteins are organized in an adhesive complex which shows similarities to the podosome and the immunological synapse. The complex was termed PILMAC. During myoblast fusion the PILMAC expands and the assembly of the structure depends on the contact of the cells but is independent from subsequent acting fusion relevant proteins. established which correlates the fusion of myoblast in Drosophila melanogaster to known fusion processes like the fusion of hypodermal cells in C. elegans.