Varshney Gaurav K, Palmer Ruth H
Umeå Center for Molecular Pathogenesis, Building 6L, Umeå University, Umeå S-901 87, Sweden.
Biochem Biophys Res Commun. 2006 Dec 29;351(4):839-46. doi: 10.1016/j.bbrc.2006.10.117. Epub 2006 Oct 30.
During embryonic development the midgut visceral muscle is formed by fusion of cells within the visceral mesoderm, a process initiated by the specification of a specialised cell type, the founder cell, within this tissue. Activation of the receptor tyrosine kinase Anaplastic lymphoma kinase (Alk) in the developing visceral muscle of Drosophila melanogaster initiates a signal transduction pathway required for muscle fusion. In this paper, we have investigated downstream components which are regulated by this novel signalling pathway. Here we show that Alk-mediated signal transduction drives the expression of the bHLH transcription factor Hand in vivo. Loss of Alk function results in a complete lack of Hand expression in this tissue, whereas Alk gain of function results in an expansion of Hand expression. Finally, we have investigated the process of muscle fusion in the gut of Hand mutant animals and can find no obvious defects in this process, suggesting that Hand is not critical for visceral muscle fusion per se.
