Swanson D A, Chang J T, Campochiaro P A, Zack D J, Valle D
Predoctoral Training Program in Human Genetics, Johns Hopkins University, Baltimore, Maryland, USA.
Invest Ophthalmol Vis Sci. 1998 Oct;39(11):2085-94.
To characterize orthologous human and murine cDNAs isolated through separate screens designed to identify genes expressed preferentially in retina.
By screening bovine, murine, and human retinal cDNA libraries, human UNC-119 clones of two varieties and a murine cDNA clone corresponding to the most abundant human transcript were isolated. Northern blot and reverse transcription-polymerase chain reaction analyses were used to determine tissue distribution of UNC-119 expression; in situ hybridization localized it in retina to photoreceptors. Fluorescence in situ hybridization was used to map the human structural gene, and its intron- exon boundaries were elucidated by polymerase chain reaction amplification and sequencing genomic DNA.
UNC-119 was expressed at high levels in photoreceptors and at low levels elsewhere. The most abundant transcript encoded a protein of 240 amino acids with homology to Caenorhabditis elegans UNC-119. Rat and human cDNAs of UNC-119 have been previously reported as human retinal gene 4 and rat retinal gene 4 (HRG4 and RRG4). An alternative splice form in humans arose from retention of the 3'-most intron, seemed to be retina-specific, and encoded a protein of 220 amino acids. The human structural gene mapped to 17q 1.2 and comprised at least five exons and four introns. A patient with neurofibromatosis type 1, which also maps to 17q11.2, and cone-rod dystrophy was examined for a deletion of UNC-119 but no abnormalities were found.
Given its strong degree of evolutionary conservation and abundant and nearly exclusive expression in photoreceptors, it is likely that UNC-119 plays an important role in vision and is a strong candidate gene for retinal diseases that map to 17q11.2.
对通过旨在鉴定在视网膜中优先表达的基因的独立筛选而分离出的直系同源人类和小鼠cDNA进行表征。
通过筛选牛、小鼠和人类视网膜cDNA文库，分离出两种类型的人类UNC-119克隆以及与最丰富的人类转录本相对应的小鼠cDNA克隆。使用Northern印迹和逆转录-聚合酶链反应分析来确定UNC-119表达的组织分布；原位杂交将其在视网膜中定位到光感受器。荧光原位杂交用于绘制人类结构基因图谱，其内含子-外显子边界通过聚合酶链反应扩增和基因组DNA测序来阐明。
UNC-119在光感受器中高水平表达，在其他地方低水平表达。最丰富的转录本编码一种与秀丽隐杆线虫UNC-119具有同源性的240个氨基酸的蛋白质。UNC-119的大鼠和人类cDNA先前已分别作为人类视网膜基因4和大鼠视网膜基因4（HRG4和RRG4）被报道。人类中的一种可变剪接形式源于最末端内含子的保留，似乎是视网膜特异性的，并且编码一种220个氨基酸的蛋白质。人类结构基因定位于17q1.2，由至少五个外显子和四个内含子组成。对一名也定位于17q11.2的1型神经纤维瘤病和锥杆营养不良患者进行了UNC-119缺失检测，但未发现异常。
鉴于其高度的进化保守性以及在光感受器中丰富且几乎排他的表达，UNC-119很可能在视觉中起重要作用，并且是定位于17q11.2的视网膜疾病的有力候选基因。
