Mason E D, Konrad K D, Webb C D, Marsh J L
Developmental Biology Center, University of California, Irvine 92717.
Genes Dev. 1994 Jul 1;8(13):1489-501. doi: 10.1101/gad.8.13.1489.
The twisted gastrulation (tsg) gene is one of seven known zygotic genes that specify the fate of dorsal cells in Drosophila embryos. Mutations in these genes cause at least some of the cells on the dorsal half of the embryo to adopt more ventral cell fates leading to the proposal that most of these genes participate in establishing, maintaining, or modulating a gradient of a single signaling molecule DECAPENTAPLEGIC (DPP). We have examined the effects of tsg mutations on the development of cuticule elements, expression of a region specific enhancer trap, and patterns of mitotic domains. Mutations of tsg only affect the fate of a narrow strip of dorsal midline cells and do not affect dorsal ectoderm cells. However, the pattern of tsg expression is not coincident with the territories affected by tsg mutations. Structural analysis of the tsg gene reveals features of a secreted protein suggesting an extracellular site of action. The TSG protein bears a weak resemblance to human connective tissue growth factor (CTGF), a TGF-beta-induced protein. We propose that dorsal midline cell fate is specified by the combination of both a TSG and a DPP signal to which the dorsal midline cells are uniquely competent to respond.
扭曲原肠胚形成（tsg）基因是已知的七个合子基因之一，这些基因决定了果蝇胚胎中背侧细胞的命运。这些基因的突变会导致胚胎背侧一半的至少一些细胞采用更多腹侧细胞的命运，这使得人们提出，这些基因中的大多数参与建立、维持或调节单一信号分子——十全大补蛋白（DPP）的梯度。我们已经研究了tsg突变对表皮元件发育、区域特异性增强子陷阱的表达以及有丝分裂域模式的影响。tsg突变仅影响背侧中线细胞的一个窄带的命运，而不影响背侧外胚层细胞。然而，tsg的表达模式与受tsg突变影响的区域并不一致。tsg基因的结构分析揭示了一种分泌蛋白的特征，表明其作用位点在细胞外。TSG蛋白与人类结缔组织生长因子（CTGF）有微弱的相似性，CTGF是一种由转化生长因子-β诱导的蛋白。我们提出，背侧中线细胞的命运是由TSG和DPP信号共同决定的，而背侧中线细胞对这两种信号具有独特的反应能力。
