Identification of a locus control region for quadruplicated green-sensitive opsin genes in zebrafish
Identification of a locus control region for quadruplicated green-sensitive opsin genes in zebrafish
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DOI：
10.1073/pnas.0704061104
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发表时间：
2007-07-31
影响因子：
11.1
通讯作者：
Kawamura, Shoji
中科院分区：
文献类型：
--
作者：
Tsujimura, Taro;Chinen, Akito;Kawamura, Shoji
视蛋白基因的复制在视觉系统的进化中起着至关重要的作用。斑马鱼有四个串联排列的绿色敏感（RH 2）视蛋白基因（RH 2 -1、RH 2 -2、RH 2 -3和RH 2 -4）。它们在双锥细胞的短成员（SDC）中表达，但在视网膜中的表达区域和其编码色素的吸收光谱方面不同。最短和第二短波长亚型RH 2 -1和RH 2 -2在中央至背侧视网膜中表达。较长波长亚型RH 2 -3表达为限制RH 2 -1/RH 2 -2区域，而最长亚型RH 2 -4表达为进一步限制RH 2 -3区域并主要占据腹侧视网膜。本报告表明，位于RH 2基因阵列上游15 kb的0.5 kb区域是其表达的重要调节因子。当0.5 kb的区域被删除的P1-人工染色体（PAC）克隆，包括四个RH 2基因，当这些基因之一被替换为报告GFP基因，GFP的表达在SDCs中被废除的斑马鱼，其中一系列的修改PAC克隆被引入。转基因研究还表明，0.5 kb的区域赋予了非SDC（UV视蛋白）和非视网膜（角蛋白8）基因启动子的SDC特异性表达。改变PAC克隆中0.5 kb区域的位置可使其近端基因获得最高表达。因此，将0.5-kb区域命名为RH 2-LCR，类似于灵长类动物L-M视蛋白基因的基因座控制区。
Duplication of opsin genes has a crucial role in the evolution of visual system. Zebrafish have four green-sensitive (RH2) opsin genes (RH2-1, RH2-2, RH2-3, and RH2-4) arrayed in tandem. They are expressed in the short member of the double cones (SDC) but differ in expression areas in the retina and absorption spectra of their encoding photopigments. The shortest and the second shortest wavelength subtypes, RH2-1 and RH2-2, are expressed in the central-to-dorsal retina. The longer wavelength subtype, RH2-3, is expressed circumscribing the RH2-1/RH2-2 area, and the longest subtype, RH2-4, is expressed further circumscribing the RH2-3 area and mainly occupying the ventral retina. The present report shows that a 0.5-kb region located 15 kb upstream of the RH2 gene array is an essential regulator for their expression. When the 0.5-kb region was deleted from a P1-artificial chromosome (PAC) clone encompassing the four RH2 genes and when one of these genes was replaced with a reporter GFP gene, the GFP expression in SDCs was abolished in the zebrafish to which a series of the modified PAC clones were introduced. Transgenic studies also showed that the 0.5-kb region conferred the SDC-specific expression for promoters of a non-SDC (UV opsin) and a nonretinal (keratin 8) gene. Changing the location of the 0.5-kb region in the PAC clone conferred the highest expression for its proximal gene. The 0.5-kb region was thus designated as RH2-LCR analogous to the locus control region of the L-M opsin genes of primates.