Fokina Valentina M, Frolova Elena I
Department of Human Biological Chemistry and Genetics, University of Texas Medical Branch, Galveston, Texas 77555-1072, USA.
Dev Dyn. 2006 Feb;235(2):496-505. doi: 10.1002/dvdy.20621.
To address the roles of Wnts in the development of the anterior eye, we used a chicken model to perform comprehensive expression analysis of all Wnt genes during anterior eye development. In analyzing the available genomic sequences, we found that the chicken genome encodes 18 Wnt proteins that are homologous to corresponding human and mouse proteins. The mRNA sequences for 12 chicken Wnt genes are available in GenBank, and mRNAs for six other Wnt genes (Wnt2, Wnt5b, Wnt7b, Wnt8b, Wnt9b, and Wnt16) were identified and cloned based on the homology to the genes from other species. In addition, we found that chicken Wnt3a and Wnt7b genes encode two alternative mRNA isoforms containing different first exons. Following in situ hybridization, we found that out of 18 Wnt genes, 11 genes were expressed in the anterior eye, exhibiting distinct temporal-spatial patterns. Several Wnts were expressed in the lens, including Wnt2 and Wnt2b in the anterior epithelium and Wnt5a, Wnt5b, Wnt7a, and Wnt7b in the differentiating lens fiber cells. In the cornea, we detected Wnt3a, Wnt6, and Wnt9b in the ocular surface ectoderm, including the corneal epithelium, and Wnt9a in the corneal endothelium from the onset of its differentiation. In the optic cup, Wnt2, Wnt2b, and Wnt9a were localized in the rim of the optic cup (presumptive iris), while Wnt5a and Wnt16 were detected in the ciliary epithelium/iris zone of the differentiated optic cup, and Wnt6 was expressed in the iridial mesenchyme. These data suggest that Wnt signaling might play important roles in anterior eye development.
为了研究Wnt信号在前眼部发育中的作用,我们使用鸡模型对前眼部发育过程中所有Wnt基因进行了全面的表达分析。在分析现有基因组序列时,我们发现鸡基因组编码18种与相应人类和小鼠蛋白同源的Wnt蛋白。12种鸡Wnt基因的mRNA序列可在GenBank中获取,另外6种Wnt基因(Wnt2、Wnt5b、Wnt7b、Wnt8b、Wnt9b和Wnt16)的mRNA则基于与其他物种基因的同源性进行了鉴定和克隆。此外,我们发现鸡Wnt3a和Wnt7b基因编码两种含有不同第一外显子的可变mRNA异构体。原位杂交后,我们发现18种Wnt基因中有11种在前眼中表达,呈现出独特的时空模式。几种Wnt在晶状体中表达,包括前上皮中的Wnt2和Wnt2b以及分化的晶状体纤维细胞中的Wnt5a、Wnt5b、Wnt7a和Wnt7b。在角膜中,我们在眼表外胚层(包括角膜上皮)中检测到Wnt3a、Wnt6和Wnt9b,在角膜内皮分化开始时检测到Wnt9a。在视杯中,Wnt2、Wnt2b和Wnt9a定位于视杯边缘(推测为虹膜),而在分化的视杯的睫状体上皮/虹膜区域检测到Wnt5a和Wnt16,Wnt6在虹膜间充质中表达。这些数据表明Wnt信号可能在前眼部发育中发挥重要作用。