Mukherjee Ashim, Melnattur Krishna V, Zhang Mao, Nambu John R
Biology Department, University of Massachusetts, Amherst, Massachusetts, USA.
Dev Dyn. 2006 Oct;235(10):2828-35. doi: 10.1002/dvdy.20904.
Members of the Sox family of DNA-binding HMG domain proteins have been shown to regulate gene transcription in a wide range of developmental processes, including sex determination, neurogenesis, and chondrogenesis. However, little is known about their potential functions in developing germline tissues. In Drosophila, the Sox protein Dichaete (a.k.a., Fish-hook) is a member of the SoxB subgroup whose HMG domain shares strong sequence similarity to that of vertebrate Sox2. Dichaete exhibits dynamic expression in embryonic and larval stages and has pleiotropic functions in a variety of tissues. In this study, we extend analyses of Dichaete function and show that expression of Dichaete protein is detected in the developing oocyte during early to mid stages of oogenesis. Strikingly, Dichaete exhibits cytoplasmic distribution and is not detected in the oocyte nucleus. Germline mosaic analyses revealed that the Dichaete gene has maternal functions that influence dorsal/ventral patterning of the egg chamber. Dichaete mutant eggs exhibit defects in formation of the dorsal appendages, differentiation of dorsal/anterior follicle cells, and mislocalization of Gurken protein and gurken mRNA. Dichaete protein was shown to possess RNA-binding capabilities, suggesting a direct post-transcriptional role in regulating RNA functions.
DNA结合HMG结构域蛋白的Sox家族成员已被证明在广泛的发育过程中调节基因转录,包括性别决定、神经发生和软骨形成。然而,它们在生殖系组织发育中的潜在功能却知之甚少。在果蝇中,Sox蛋白双胸(又名鱼钩)是SoxB亚组的成员,其HMG结构域与脊椎动物Sox2的HMG结构域具有很强的序列相似性。双胸在胚胎和幼虫阶段表现出动态表达,并在多种组织中具有多效性功能。在本研究中,我们扩展了对双胸功能的分析,并表明在卵子发生的早期到中期,在发育中的卵母细胞中检测到双胸蛋白的表达。令人惊讶的是,双胸表现出细胞质分布,在卵母细胞核中未检测到。生殖系嵌合体分析表明,双胸基因具有母体功能,影响卵室的背/腹模式。双胸突变体卵子在背附肢形成、背/前卵泡细胞分化以及Gurken蛋白和gurken mRNA的错误定位方面存在缺陷。双胸蛋白被证明具有RNA结合能力,这表明它在调节RNA功能方面具有直接的转录后作用。