tinman and bagpipe: two homeo box genes that determine cell fates in the dorsal mesoderm of Drosophila.

Abstract

Whereas the mechanisms of early Drosophila mesoderm formation have been studied in much detail, the subsequent processes determining regional identities within the mesoderm remain largely unknown. Here, we describe two homeo box genes, tinman (tin) and bagpipe (hap), which spatially subdivide the mesoderm and

Xenopus bagpipe‐related gene, koza, may play a role in regulation of cell proliferation

“…For both genes, expression commences well in advance of differentiation marker expression (Newman et al, 1997b;Newman and Krieg, 1999). Expression in the developing gut may represent a conservation of function relative to the fly where bap plays a critical role in the specification of visceral musculature (Azpiazu and Frasch, 1993). In contrast, koza, the most divergent Xenopus family member at the amino acid level, is expressed in the somatic musculature and is completely absent from the gut.…”

“…The Drosophila bagpipe gene is transiently expressed in the dorsal vessel before differentiation (Azpiazu and Frasch, 1993). This expression is dependent on tinman gene function.…”

“…In Drosophila, the bagpipe (bap) homeobox gene is expressed predominantly in precursors of the visceral musculature and is required for midgut development (Azpiazu and Frasch, 1993). bap-related genes have now been isolated from several vertebrate species, including the frog.…”

“…B: A comparison of the homeodomains of several bagpipe family members, including those from frog (koza, Xbap, and zax), mouse (BapX1, Nkx3-1), and Drosophila (bap). The homeodomain sequences were obtained from the following references, Xbap (Newman et al, 1997b), zax (Newman and Krieg, 1999), BapX1 (Sciavolino et al, 1997), Nkx3-1 (Tribioli et al, 1997), and bap (Azpiazu and Frasch, 1993). pogna (zax), are expressed in the muscular layer of the midgut and also in a nonoverlapping subset of facial cartilages (Newman et al, 1997b;Newman and Krieg, 1999).…”

Mes2, a MADF‐containing transcription factor essential for Drosophila development

“…In Drosophila, the interplay of transcriptional hierarchies as well as signaling networks specifies how the early undifferentiated mesoderm gives rise to a highly stereotyped system of muscle fibers in larvae and adults (reviewed in Frasch, 1999;Baylies and Michelson, 2001;Furlong, 2004). Work over the past 2 decades has led to the identification of several key transcriptional regulators involved in mesoderm specification and differentiation (Boulay et al, 1987;Thisse et al, 1987;Azpiazu and Frasch, 1993;Taylor et al, 1995). This work established that twist, an evolutionarily conserved basic helix-loophelix transcription factor (reviewed in Castanon and Baylies, 2002), constitutes the top of a genetic hierarchy that specifies the formation of the early mesoderm.…”