Regulation of Nucleoside Transporters by Protein Kinases

描述（由申请方提供）：平衡型核苷转运蛋白是摄取核苷和化疗核苷类似物（例如Ara-C、吉西他滨）所必需的整合膜蛋白。在联合化疗（即顺铂、放疗）后观察到对核苷类似物的敏感性增强，尽管对这些作用的机制知之甚少。平衡型核苷转运蛋白（ENT 1/2）广泛表达，并根据细胞对有丝分裂原或应激信号的暴露而受到差异调节。目前，控制这些转运蛋白的转录调控的分子事件是未知的。本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ENT 1/2在核苷摄取和嘧啶核苷酸补救合成中的需要。具体来说，我们的研究指出了Src和应激激活的c-Jun激酶（JNK）在调节ENT 1/2表达中的关键作用。因此，本提案的目的是表征ENT 1/2的转录调节所必需的激酶依赖性信号，并确定该事件对细胞增殖或存活的影响。此外，我们将确定所需的激酶介导的调节ENT 1/2表达的启动子元件。最后，我们将研究JNK的激活是否参与细胞对核苷类似物的上调和增强的敏感性。该提案的具体目标是： 目标1。确定参与ENT 1/2表达调节的特定蛋白激酶。 目标2。阐明ENT 1和ENT 2表达所必需的启动子元件。 目标3。检查ENT在生长、分化和化学增敏中的特定作用 .

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 .