Peptide/Mimetic Transport Mechanisms in Choroid Plexus

描述(来自应用程序的逐字)：与肠道和 肾脏，对多肽的细胞和分子机制知之甚少 以及血液和大脑之间的模拟肽运输。这是不幸的，因为 形成血管内皮细胞的内皮细胞之间的紧密连接 血脑屏障(BBB)和脉络丛上皮细胞构成 血-脑脊液屏障(BCSFB)限制细胞旁运动。因此， 跨细胞转运需要特定的转运体。 亲水性化合物，无论是用于营养物质进入大脑还是 毒素从大脑中排出。脑内多肽转运体的存在 (即PEPT2和PHT1)引起了相当大的兴趣，因为它们的精确 神经肽动态平衡的解剖位置、作用及意义 底物贩运，以及作为药物输送系统的潜力 血脑和/或脑脊液屏障。我们实验室的新发现有 确定了一种高亲和力多肽的功能和分子存在 转运蛋白PEPT2在大鼠全组织脉络丛中的表达。这些初步的 结果提示PEPT2在多肽的摄取过程中可能起重要作用。 它们起着神经调节剂的作用，清除降解的神经肽，以及 某些头孢菌素类药物从脉络膜上皮细胞外流。我们的工作 假设PEPT2在脉络丛的顶膜中表达 作为主要的外排泵，清除神经肽片段和 脑脊液中的多肽类药物。为了检验这一假设， 提出了以下具体目标：目标1.定义功能 多肽在大鼠脉络丛上皮细胞的转运特性 原代培养的细胞；目的2.确定组织分布和 哺乳动物脑内特异性寡肽转运体的膜定位； 目的3.建立和验证编码PEPT2基因的小鼠模型 已经被有针对性的基因破坏所破坏。这个项目的长期目标是 竞争性的更新应用是定义细胞和分子 多肽及其类药物转运机制的研究进展 脉络丛。结合免疫球蛋白的实验和研究 PEPT2基因缺陷的小鼠，拟议的研究将极大地推动我们的 对多肽的作用、意义和载体转运的认识 脑组织中PEPT2的底物(与PHT1和其他潜力相比较 运输商)。此外，在解决肽的基本问题时， 转运蛋白的活性、表达和意义，拟议的研究可能 对中枢神经系统疾病的治疗有重要意义(例如， 阿尔茨海默病、艾滋病痴呆症、中风、癫痫、精神分裂症和癌症) 以及在药物设计、给药和靶向方面提供新的战略 大脑。

DESCRIPTION (Verbatim from the application): In contrast to the intestine and kidney, little is known about the cellular and molecular mechanisms of peptide and peptidomimetic transport between blood and brain. This is unfortunate since the presence of tight junctions between the endothelial cella that form the blood-brain barrier (BBB) and the choroid plexus epithelial cells that form the blood-cerebrospinal fluid barrier (BCSFB) limit paracellular movement. Thus, specific transporters are required for the transcellular transport of hydrophilic compounds whether for the movement of nutrients into the brain or toxins out of the brain. The presence of peptide transporters within the brain (i.e., PEPT2 and PHT1) has generated considerable interest as to their precise anatomical location, role in neuropeptide homeostasis, significance in substrate trafficking, and potential as a drug delivery system through the blood brain and/or CSF barriers. Novel findings in our laboratory have established the functional and molecular presence of a high-affinity peptide transporter, PEPT2, in whole tissue rat choroid plexus. These preliminary results suggest that PEPT2 may play an important role in the uptake of peptides which function as neuromodulators, the clearance of degraded neuropeptides, and the efflux of some cephalosporin drugs from choroidal epithelium. Our working hypothesis is that PEPT2 is expressed in apical membranes of the choroid plexus and functions as the primary efflux pump in removing neuropeptide fragments and peptide-like drugs from cerebrospinal fluid. To test this hypothesis, the following specific aims are proposed: Aim 1. To define the functional characteristics of peptide-mediated transport in rat choroid plexus epithelial cells in primary culture; Aim 2. To determine the tissue distribution and membrane localization of specific oligopeptide transporters in mammalian brain; Aim 3. To develop and validate a mouse model in which the gene encoding PEPT2 has been ablated by targeted gene disruption. The long-term objectives of this competing renewal application are to define the cellular and molecular mechanisms involved in the transport of peptides and peptide-like drugs in choroid plexus. Combined with immunoloclization experiments and studies in PEPT2-deficient mice, the proposed studies will greatly advance our understanding of the role, significance and vectorial transport of peptide substrates by PEPT2 in brain (as compared to PHT1 and other potential transporters). Moreover, in addressing fundamental questions of peptide transporter activity, expression and significance, the proposed studies may have important implications for the treatment of CNS disorders (e.g., Alzheimer's disease, AIDS dementia, stroke, epilepsy, schizophrenia and cancer) and for providing new strategies in drug design, delivery and targeting to the brain.