Jones D, Stringham E G, Graham R W, Candido E P
Department of Biochemistry and Molecular Biology, University of British Columbia, Vancouver, Canada.
Dev Biol. 1995 Sep;171(1):60-72. doi: 10.1006/dbio.1995.1260.
The Caenorhabditis elegans ubq-2 gene encodes a fusion of ubiquitin and a 52-amino-acid ribosomal protein. This single copy gene is both cis- and trans-spliced. It is expressed in all life stages of the worm and its transcript abundance is unaffected by heat stress. Transgenic analysis shows that expression of ubq-2 is regulated by an upstream promoter and a downstream element. The downstream element is required for ubq-2 promoter activity in embryos and in cells of the somatic gonad, including the distal tip cells, sheath cells, spermathecal cells, and cells of the uterus. The gonad-specific activity of the downstream regulator is transferable to a stress gene promoter such that heat-inducible expression of the transgene occurs in the somatic gonad. Stress-inducible beta-galactosidase expression in the gonad does not occur in all life stages, but is initiated late in the second or early in the third larval stage, when differentiation of gonadal tissues begins. Expression of a beta-galactosidase fusion protein from constructs containing the downstream ubq-2 regulator causes abnormalities of the gonad and embryonic lethality. Gonad abnormalities include arrested development and general disorganization. These abnormalities may be related to the overexpression of ubiquitin in the gonad.
秀丽隐杆线虫的ubq-2基因编码一种泛素与一个52个氨基酸的核糖体蛋白的融合蛋白。这个单拷贝基因进行顺式剪接和反式剪接。它在蠕虫的所有生命阶段都有表达，其转录本丰度不受热应激影响。转基因分析表明，ubq-2的表达受上游启动子和下游元件调控。下游元件对于ubq-2在胚胎以及包括远端末梢细胞、鞘细胞、受精囊细胞和子宫细胞在内的体细胞性腺细胞中的启动子活性是必需的。下游调节因子的性腺特异性活性可转移至一个应激基因启动子，使得转基因在体细胞性腺中发生热诱导表达。性腺中应激诱导的β-半乳糖苷酶表达并非在所有生命阶段都出现，而是在第二幼虫期晚期或第三幼虫期早期开始，此时性腺组织开始分化。来自含有下游ubq-2调节因子的构建体的β-半乳糖苷酶融合蛋白的表达会导致性腺异常和胚胎致死。性腺异常包括发育停滞和普遍的紊乱。这些异常可能与性腺中泛素的过度表达有关。
