TINMAN AND BAGPIPE - 2 HOMEO BOX GENES THAT DETERMINE CELL FATES IN THE DORSAL MESODERM OF DROSOPHILA
TINMAN AND BAGPIPE - 2 HOMEO BOX GENES THAT DETERMINE CELL FATES IN THE DORSAL MESODERM OF DROSOPHILA
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DOI：
10.1101/gad.7.7b.1325
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发表时间：
1993-07-01
影响因子：
10.5
通讯作者：
FRASCH, M
中科院分区：
文献类型：
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作者：
AZPIAZU, N;FRASCH, M
虽然早期果蝇中胚层形成的机制已经被详细研究过，但决定中胚层区域特征的后续过程在很大程度上仍然未知。在这里，我们描述了两个同源盒基因，tinman （tin）和bagpipe (bap)，它们在空间上细分了中胚层，并决定了中胚层背面的细胞命运。这两个基因是一系列遗传相互作用的组成部分，这些相互作用导致tin mRNA在中胚层背侧的空间限制，并在该区域的细胞节段簇中激活bap。这些细胞簇中的一部分分离形成内脏中胚层，并分化成肠道肌肉组织。这表明内脏中胚层来源于元胞重复的原基。在bap突变的胚胎中，内脏中胚层的形成被严重破坏。内脏中胚层细胞大部分不能正常分化，部分转化为体壁肌肉组织和性腺中胚层。在锡突变胚中，bap的表达在背中胚层中不被激活。可能因此，在这些突变体中既没有形成内脏中胚层，也没有形成中肠肌肉组织，内脏中胚层的缺失导致内胚层迁移和中肠形态发生的严重中断。除了内脏中胚层的发育外，锡还需要从背胚层形成心脏和特定体壁肌肉的创始细胞。
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 (bap), which spatially subdivide the mesoderm and determine cell fates in the dorsal mesoderm. These two genes are components of a cascade of genetic interactions that result in the spatial restriction of tin mRNA to the dorsal mesoderm and in the activation of bap in segmental clusters of cells in this region. A subset of cells from those clusters segregate to form visceral mesoderm that differentiates into gut musculature. This indicates that the visceral mesoderm is derived from metamerically repeated primordia. In embryos mutant for bap, visceral mesoderm formation is strongly disrupted. Most cells of the visceral mesoderm fail to differentiate properly, and a portion of them are transformed into body wall musculature and gonadal mesoderm. In tin mutant embryos, bap expression is not activated in the dorsal mesoderm. Probably as a consequence, neither visceral mesoderm nor midgut musculature are formed in these mutants, and the absence of visceral mesoderm results in strong disruptions of endoderm migration and midgut morphogenesis. In addition to visceral mesoderm development, tin is required for the formation of the heart from dorsal mesoderm and for the specification of founder cells for particular body wall muscles.