Role of Mef2 in Drosophila muscle development
Hancock, Daniel H.
mesheuropmc: cardiovascular system | tissues | embryonic structures | musculoskeletal system | animal structures
Muscle differentiation is a complex process involving the transition from undifferentiated mesoderm to a final functional musculature. Mef2 is an essential positive regulator central to the co-ordination of this process. It targets a plethora of key genes both early and late in the differentiation program and its activity must be tightly controlled (Pothoff and Olson, 2007). The aim of my research was to investigate the role of Mef2 in orchestrating Drosophila muscle differentiation. I did this by analysing the formation of the larval somatic musculature under conditions that either increased or decreased Mef2 activity using gain and loss-of -function of either Mef2 itself, Him, a repressor of Mef2 activity (Liotta et al, 2007) or of Zfhl, a potential regulator of Mef2 expression (Postigo et al, 1999). Part of this investigation involved the generation and characterisation of Mef2 dominant negative proteins and isolation of a Him mutant. Detailed analysis revealed a distinct subset of somatic muscles that are missing when Mef2 activity is reduced and another subset of muscles that are duplicated when Mef2 activity is increased. This suggests a role for Mef2 in patterning of the musculature that has not been established previously. In addition, I identified a role for Mef2 in the regulation of Him expression, revealing a mechanism whereby Mef2 could be involved in its own repression. I also investigated the role of mesol8E in muscle differentiation a previously uncharacterised novel gene identified as an early target of Mef2 (Taylor, 2000). I found this to be a Myb-like domain containing protein that is a direct target of Mef2. Over-expression caused a severe disruption to the somatic musculature, revealing a potential role for mesol8E in muscle guidance. Generation of mesol8E mutant alleles by FRT element mediated recombination showed the gene to be essential for development.