Muscle development and attachment to the epidermis is accompanied by expression of beta 3 and beta 1 tubulin isotypes, respectively.
In Drosophila beta tubulins are encoded by a small gene family whose members are differentially expressed in a highly cell and tissue specific manner. Here we focus on the expression of the beta 3 tubulin isotype during mesoderm differentiation and beta 1 tubulin expression in the apodemes during embryonic development. The beta 3 tubulin isotype is first detectable at the extended germband stage shortly before the separation of somatic and visceral derivatives. Comparing the distribution of the beta 3 mRNA and the beta 3 isotype shows that the transcription of the beta 3 tubulin gene is cell type specifically repressed during differentiation of individual mesodermal derivatives, from which the dorsal vessel remains transcriptionally active until shortly before hatching. In contrast the beta 3 tubulin protein is detectable in all mesodermal derivatives. The beta 3 tubulin is an excellent marker to study mesoderm differentiation on a regulatory and cellular level using both genetics and molecular biology. In the visceral mesoderm, the expression of the beta 3 tubulin gene is regulated by homeotic gene products, while other transactivators regulate expression in the dorsal vessel and the body wall musculature. In the somatic mesoderm, the beta 3 tubulin allows to visualize myotube formation and insertion into the epidermis. This contact to the epidermal attachment sites (apodemes) induces beta 1 tubulin expression, as can be seen in double staining experiments. We determined a 14bp cis-regulatory enhancer element guiding expression of the beta 1 tubulin gene in these attachment sites. Using the beta 1 and beta 3 tubulin isotypes as markers we started to isolate mutants which are disturbed in muscle formation.
Buttgereit
D
D
FB Biologie, Marburg, Germany. Buttgere@mailer.uni-marburg.de
Paululat
A
A
Renkawitz-Pohl
R
R
D000818:Animals; D004330:Drosophila / Q000196:embryology* / Q000235:genetics* / Q000378:metabolism; D018507:Gene Expression Regulation, Developmental; D017344:Genes, Insect; D008648:Mesoderm / Q000378:metabolism; D009132:Muscles / Q000196:embryology* / Q000378:metabolism*; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D015534:Trans-Activators / Q000235:genetics; D014404:Tubulin / Q000235:genetics*
D012333:RNA, Messenger; D015534:Trans-Activators; D014404:Tubulin