Appleford Peter J, Griffiths Mark, Yao Sylvia Y M, Ng Amy M L, Chomey Eugene G, Isaac R Elwyn, Coates David, Hope Ian A, Cass Carol E, Young James D, Baldwin Stephen A
School of Biochemistry & Microbiology, University of Leeds, Leeds LS2 9JT, UK.
Mol Membr Biol. 2004 Jul-Aug;21(4):247-59. doi: 10.1080/09687680410001712550.
The genome of Caenorhabditis elegans encodes multiple homologues of the two major families of mammalian equilibrative and concentrative nucleoside transporters. As part of a programme aimed at understanding the biological rationale underlying the multiplicity of eukaryote nucleoside transporters, we have now demonstrated that the nematode genes ZK809.4 (ent-1) and K09A9.3 (ent-2) encode equilibrative transporters, which we designate CeENT1 and CeENT2 respectively. These transporters resemble their human counterparts hENT1 and hENT2 in exhibiting similar broad permeant specificities for nucleosides, while differing in their permeant selectivities for nucleobases. They are insensitive to the classic inhibitors of mammalian nucleoside transport, nitrobenzylthioinosine, dilazep and draflazine, but are inhibited by the vasoactive drug dipyridamole. Use of green fluorescent protein reporter constructs indicated that the transporters are present in a limited number of locations in the adult, including intestine and pharynx. Their potential roles in these tissues were explored by using RNA interference to disrupt gene expression. Although disruption of ent-1 or ent-2 expression alone had no effect, simultaneous disruption of both genes yielded pronounced developmental defects involving the intestine and vulva.
秀丽隐杆线虫的基因组编码了哺乳动物平衡型和浓缩型核苷转运蛋白两个主要家族的多个同源物。作为旨在理解真核生物核苷转运蛋白多样性背后生物学原理的研究计划的一部分，我们现已证明线虫基因ZK809.4（ent-1）和K09A9.3（ent-2）编码平衡型转运蛋白，我们分别将其命名为CeENT1和CeENT2。这些转运蛋白与其人类对应物hENT1和hENT2相似，对核苷表现出相似的广泛通透特异性，而对核碱基的通透选择性不同。它们对哺乳动物核苷转运的经典抑制剂硝基苄硫肌苷、双嘧达莫和群多普利不敏感，但被血管活性药物双嘧达莫抑制。使用绿色荧光蛋白报告构建体表明，这些转运蛋白在成虫的有限位置存在，包括肠道和咽部。通过使用RNA干扰破坏基因表达来探索它们在这些组织中的潜在作用。尽管单独破坏ent-1或ent-2的表达没有影响，但同时破坏这两个基因会导致涉及肠道和阴门的明显发育缺陷。
