The Drosophila homeobox genes zfh-1 and even-skipped are required for cardiac-specific differentiation of a numb-dependent lineage decision.
A series of inductive signals are necessary to subdivide the mesoderm in order to allow the formation of the progenitor cells of the heart. Mesoderm-endogenous transcription factors, such as those encoded by twist and tinman, seem to cooperate with these signals to confer correct context and competence for a cardiac cell fate. Additional factors are likely to be required for the appropriate specification of individual cell types within the forming heart. Similar to tinman, the zinc finger- and homeobox-containing gene, zfh-1, is expressed in the early mesoderm and later in the forming heart, suggesting a possible role in heart development. Here, we show that zfh-1 is specifically required for formation of the even-skipped (eve)-expressing subset of pericardial cells (EPCs), without affecting the formation of their siblings, the founders of a dorsal body wall muscle (DA1). In addition to zfh-1, mesodermal eve itself appears to be needed for correct EPC differentiation, possibly as a direct target of zfh-1. Epistasis experiments show that zfh-1 specifies EPC development independently of numb, the lineage gene that controls DA1 founder versus EPC cell fate. We discuss the combinatorial control mechanisms that specify the EPC cell fate in a spatially precise pattern within the embryo.
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Department of Biology, University of Michigan, Ann Arbor, MI 48109-1048, USA.
Fujioka
M
M
Goto
T
T
Bodmer
R
R
D000818:Animals; D030801:Animals, Genetically Modified; D001426:Bacterial Proteins; D001665:Binding Sites; D002454:Cell Differentiation / Q000235:genetics; D004268:DNA-Binding Proteins / Q000235:genetics* / Q000378:metabolism; D004330:Drosophila / Q000235:genetics*; D029721:Drosophila Proteins; D004625:Embryo, Nonmammalian; D004742:Enhancer Elements, Genetic; D004815:Epidermal Growth Factor / Q000378:metabolism; D018507:Gene Expression Regulation, Developmental; D006321:Heart / Q000196:embryology; D006330:Heart Defects, Congenital / Q000235:genetics; D018398:Homeodomain Proteins / Q000235:genetics* / Q000378:metabolism; D007605:Juvenile Hormones / Q000235:genetics / Q000378:metabolism*; D008648:Mesoderm / Q000502:physiology; D009154:Mutation; D009206:Myocardium / Q000166:cytology*; D012097:Repressor Proteins; D013234:Stem Cells / Q000378:metabolism; D015534:Trans-Activators; D014157:Transcription Factors
D001426:Bacterial Proteins; D004268:DNA-Binding Proteins; D029721:Drosophila Proteins; D018398:Homeodomain Proteins; D007605:Juvenile Hormones; D012097:Repressor Proteins; D015534:Trans-Activators; D014157:Transcription Factors; C052837:eve protein, Drosophila; C060606:numb protein, Drosophila; C102933:tin protein, Drosophila; C081010:zfh1 protein, Drosophila; D004815:Epidermal Growth Factor