Regulation of Nucleoside Transporters by Protein Kinases

描述(由申请人提供)：平衡的核苷转运体是对核苷和化疗核苷类似物(例如Ara-C、吉西他滨)的摄取至关重要的完整的膜蛋白。在联合化疗(即顺铂、放疗)后，已经观察到对核苷类似物的敏感性增加，尽管对这些作用的机制(S)尚不清楚。平衡的核苷转运蛋白(ENT1/2)普遍表达，并根据细胞对有丝分裂原或应激信号的暴露而受到不同的调节。目前，控制这些转运蛋白转录调控的分子事件尚不清楚。我们实验室一直在研究蛋白激酶对嘧啶核苷酸合成的调控。我们最近的研究集中在核苷的摄取和嘧啶核苷酸的残存合成中对ENT1/2的需求。具体地说，我们的研究指出了Src和应激激活的c-jun激酶(JNK)在ENT1/2表达调控中的关键作用。因此，本研究的目的是确定ENT1/2转录调控所必需的依赖于激酶的信号，并确定这一事件对细胞增殖或存活的影响。此外，我们还将确定激酶介导的ENT1/2表达调控所需的启动子元件。最后，我们将研究JNK的激活是否参与了细胞对核苷类似物的上调和增敏。这项建议的具体目标是： 目的#1.确定特异性蛋白激酶参与调节ENT1/2的表达。 目的#2.阐明ENT1和ENT2表达所需的启动子元件。 目的#3.研究Ents在生长、分化和化疗增敏中的特殊作用。

DESCRIPTION (provided by applicant): The equilibrative nucleoside transporters are integral membrane proteins that are essential for the uptake of nucleosides and chemotherapeutic nucleoside analogs (e.g. Ara-C, gemcitabine). Enhanced sensitivity to nucleoside analogs has been observed after combined chemotherapy (i.e. cisplatinum, irradiation), although the mechanism(s) responsible for these effects are poorly understood. The equilibrative nucleoside transporters (ENT1/2) are ubiquitously expressed and are differentially regulated depending on the exposure of cells to mitogens or stress signals. At present, the molecular events that control the transcriptional regulation of these transporters are unknown. Our lab has been investigating the regulation of pyrimidine nucleotide synthesis by protein kinases. Our recent studies have focused on the requirement of ENT 1/2 in the uptake of nucleoside and the salvage synthesis of pyrimidine nucleotides. Specifically our studies have pointed to a crucial role for Src and the stress-activated c-Jun kinases (JNK) in the regulation of ENT1/2 expression. Thus the objective of this proposal is to characterize the kinase-dependent signals that are necessary for the transcriptional regulation of ENT 1/2, and to determine the impact of this event on cell proliferation or survival. In addition, we will determine the promoter elements that are required for kinase-mediated regulation of ENT1/2 expression. Finally, we will investigate whether activation of JNK is involved in the up-regulation and enhanced sensitization of cells to nucleoside analogs. The Specific Aims of the proposal are: Aim #1. Determine the involvement of specific protein kinases in the regulation of ENT1/2 expression. Aim #2. Elucidate the promoter elements necessary for the expression of ENT1 and ENT2. Aim #3. Examine the specific roles of ENTs in growth, differentiation and chemosensitization .