金鱼Vsx1基因结构及其内含子多态性分析

Vsx1是第一个在金鱼中发现的编码含有同源异型框(homeodomain)和CVC结构域蛋白的基因。该基因在胚胎发育的不同阶段在胚胎的不同区域和不同组织中表达,并已经证明它在视网膜视锥双极细胞的分化和正常功能的维持中具有重要作用。为了进一步研究该基因在不同发育阶段组织特异性表达的调节机制,实验用PCR方法分析了金鱼Vsx1的基因组结构和内含子多态性。结果表明:金鱼Vsx1基因由5个外显子和4个内含子组成,与斑马鱼、人、小鼠的Vsx1基因结构相同。4个内含子中,第一内含子有两种序列差异明显的类型,但第二、三、四内含子无明显差异。第一内含子的一种类型比另外一种类型多39个碱基,这39个碱基中包括了真核生物增强子的核心序列。这一观测结果提示金鱼Vsx1第一内含子可能与该基因的发育阶段特异性和组织特异性表达调节有关。同时,第一内含子序列的明显差异也为分析Vsx1不同等位基因或基因拷贝的表达活性,以及组织特异性表达调节方式提供了合适的探针序列。

Analysis on Genomic Structure and Intron Polymorphism of Goldfish Vsx1

Visual system homeobox-1(Vsx1) is a homeobox gene encoding a homeodomain and a CVC domain that was first cloned from an adult goldfish retinal library.This gene is expressed in different regions and tissues of the embryo during development.It plays a pivotal role in differentiation and maintenance of retinal bipolar cells.To study the regulatory mechanism of Vsx1 expression,we analyzed the genomic structure and intron polymorphism of goldfish Vsx1 by PCR.The gene was found to consist of five exons and four introns.The exon-intron structure is conserved among zebrafish Vsx1,mouse Vsx1 and human Vsx1.Two obviously different categories were determined in the first intron of golefish Vsx1,one has 39 base pairs,which contain a core sequence of eukaryote enhancer,more than the other.No significant divergence was detected in the other three introns.The results suggest that the first intron of goldfish Vsx1 may be associated with the expression regulatory of Vsx1.The significant polymorphism in the first intron of goldfish Vsx1 also provides us with suitable probes to analyze expression levels of Vsx1 at the same loci or different locus as well as the regulatory mechanism of Vsx1 tissue-specific expression.