Eisenberg L M, Ingham P W, Brown A M
Department of Cell Biology and Anatomy, Cornell University Medical College, New York, New York 10021.
Dev Biol. 1992 Nov;154(1):73-83. doi: 10.1016/0012-1606(92)90049-m.
The Wnt gene family in vertebrates comprises at least 11 distinct genes but the only family member previously identified in Drosophila has been the segment polarity gene wingless (wg), the ortholog of vertebrate Wnt-1. In this report we describe the isolation of a novel Drosophila Wnt gene, Dwnt-5, which differs significantly from wg in both the pattern of its expression during embryogenesis and the predicted structure of its product. Dwnt-5 encodes a polypeptide of 112 kDa, which is more than twice as large as the products of previously known Wnt genes. The protein shares homology with other Wnt sequences in its carboxy-terminal half only and is most closely related to the products of vertebrate Wnt-5a and Wnt-5b. Dwnt-5 is expressed in a complex pattern during Drosophila embryogenesis. At the extended germ band stage, however, transcripts accumulate specifically in the nascent limb primordia of the head and thoracic segments. We show that this elevated expression depends on the activity of the homeobox gene Distal-less (Dll) and suggest that the Dwnt-5 gene may constitute a downstream target of Dll that acts in the specification of these primordia.
脊椎动物中的Wnt基因家族至少由11个不同的基因组成，但此前在果蝇中鉴定出的唯一家族成员是节段极性基因无翅（wg），它是脊椎动物Wnt-1的直系同源基因。在本报告中，我们描述了一种新型果蝇Wnt基因Dwnt-5的分离，该基因在胚胎发育过程中的表达模式及其产物的预测结构上均与wg有显著差异。Dwnt-5编码一种112 kDa的多肽，其大小是此前已知Wnt基因产物的两倍多。该蛋白质仅在其羧基末端一半与其他Wnt序列具有同源性，并且与脊椎动物Wnt-5a和Wnt-5b的产物关系最为密切。Dwnt-5在果蝇胚胎发育过程中以复杂的模式表达。然而，在延伸胚带阶段，转录本特异性地积累在头部和胸部节段的新生肢体原基中。我们表明这种表达升高依赖于同源异型框基因无距（Dll）的活性，并提出Dwnt-5基因可能构成Dll的下游靶点，在这些原基的特化中起作用。
