Houston D W, Zhang J, Maines J Z, Wasserman S A, King M L
University of Miami School of Medicine, Department of Cell Biology and Anatomy, FL 33101, USA.
Development. 1998 Jan;125(2):171-80. doi: 10.1242/dev.125.2.171.
We have identified a localized RNA component of Xenopus germ plasm. This RNA, Xdazl (Xenopus DAZ-like), encodes a protein homologous to human DAZ (Deleted in Azoospermia), vertebrate DAZL and Drosophila Boule proteins. Human males deficient in DAZ have few or no sperm and boule mutant flies exhibit complete azoospermia and male sterility. Xdazl RNA was detected in the mitochondrial cloud and vegetal cortex of oocytes. In early embryos, the RNA was localized exclusively in the germ plasm. Consistent with other organisms, Xdazl RNA was also expressed in the spermatogonia and spermatocytes of frog testis. Proteins in the DAZ-family contain a conserved RNP domain implying an RNA-binding function. We have shown that Xdazl can function in vitro as an RNA-binding protein. To determine if the function of Xdazl in spermatogenesis was conserved, we introduced the Xdazl cDNA into boule flies. This resulted in rescue of the boule meiotic entry phenotype, including formation of spindles, phosphorylation of histone H3 and completion of meiotic cell division. Overall, these results suggest that Xdazl may be important for primordial germ cell specification in the early embryo and may play a role analogous to Boule in promoting meiotic cell division.
我们已经鉴定出非洲爪蟾生殖质中的一种局部RNA成分。这种RNA，即Xdazl（非洲爪蟾类DAZ），编码一种与人类DAZ（无精子症缺失基因）、脊椎动物DAZL和果蝇Boule蛋白同源的蛋白质。缺乏DAZ的人类男性精子很少或没有，而boule突变果蝇表现出完全无精子症和雄性不育。在卵母细胞的线粒体云团和植物性皮质中检测到Xdazl RNA。在早期胚胎中，这种RNA仅定位于生殖质中。与其他生物一致，Xdazl RNA也在蛙类睾丸的精原细胞和精母细胞中表达。DAZ家族中的蛋白质含有一个保守的RNP结构域，这意味着其具有RNA结合功能。我们已经证明Xdazl在体外可作为一种RNA结合蛋白发挥作用。为了确定Xdazl在精子发生中的功能是否保守，我们将Xdazl cDNA导入boule果蝇中。这导致了boule减数分裂起始表型的拯救，包括纺锤体的形成、组蛋白H3的磷酸化以及减数分裂细胞分裂的完成。总体而言，这些结果表明Xdazl可能对早期胚胎中原始生殖细胞的特化很重要，并且可能在促进减数分裂细胞分裂中发挥类似于Boule的作用。
