Role and Relevance of Pept1 in Drug Absorption, Disposition, and Dynamics

描述（由申请人提供）：PEPT1是SLC15家族的质子偶联寡肽转运蛋白（POT），具有重要的营养价值，因为它能从肠道吸收日粮中的小肽，并从肾小球滤液中重新吸收肽结合的氨基氮。PEPT1在转运治疗剂方面也具有药理意义(例如？-内酰胺类抗生素、血管紧张素转换酶抑制剂、抗病毒核苷前药)和潜在毒性的拟肽制剂（如5-氨基乙酰丙酸）。然而，POT家族的其他成员（即PEPT2、PHT1和PHT2）在肠道和肾脏中表达，从而混淆了对其作用和相关性的准确评估。我们的实验室最近建立了一个PEPT1敲除小鼠群体，这是一个独特的资源，可以通过体内全动物实验验证原位机制研究。考虑到最近异常的PEPT1结肠表达与炎症性肠病进展之间的关联，这些基因敲除小鼠的可用性尤其令人兴奋。考虑到这一点，此次“重新提交”申请的长期目标是确定PEPT1的生理、药理学和病理作用及其相关性。我们的工作假设是，PEPT1是肠内多肽和肽样药物吸收、处置和动态的关键转运蛋白，在肠道炎症的发病机制中起重要作用。为了验证这一假设，提出了以下具体目标：目标1。测定肽样药物（和前药）、细菌衍生肽和抗炎三肽的原位肠转运特性；目标2。描述肽样药物（和前药）和抗炎三肽的体内吸收和处置；和Aim 3。评估PEPT1在介导细菌衍生肽和抗炎三肽的炎症反应中的作用和相关性。通过结合野生型小鼠和PEPT1缺失小鼠的细胞/组织、分子和全动物研究，所提出的研究将极大地促进我们对肽、肽样药物（和前药）通过PEPT1（与其他转运蛋白和/或被动过程相反）在体内的作用、意义和载体运输的理解。此外，我们的研究结果将为PEPT1介导的肠道炎症机制提供重要的新见解，并因此确定针对炎症性肠病的治疗策略的新靶点。最后，提出的研究可能提供罕见的洞察多肽/模拟动力学和反应的可变性在那些人类受试者遗传多态性。

DESCRIPTION (provided by applicant): PEPT1, a proton-coupled oligopeptide transporter (POT) of the SLC15 family, has nutritional importance because of its intestinal absorption of small peptides from the diet and because of its reabsorption of peptide-bound amino nitrogen from glomerular filtrate in kidney. PEPT1 also has pharmacological significance in its ability to transport therapeutic agents (e.g., ?-lactam antibiotics, angiotensin-converting enzyme inhibitors, antiviral nucleoside prodrugs) and potentially toxic peptidomimetics (e.g., 5-aminolevulinic acid). However, other members of the POT family (i.e., PEPT2, PHT1 and PHT2) are expressed in the intestine and kidney, thereby confounding an accurate assessment of its role and relevance. Our laboratory has recently established a colony of PEPT1 knockout mice, a unique resource in which to validate in situ mechanistic studies with in vivo whole animal experiments. The availability of these knockout mice is particularly exciting given the recent association of aberrant PEPT1 colonic expression and inflammatory bowel disease progression. With this in mind, the long-term objectives of this "resubmission" application are to define the physiological, pharmacological, and pathological roles and relevance of PEPT1. Our working hypothesis is that PEPT1 is a critical transporter in the intestinal absorption, disposition, and dynamics of peptides and peptide-like drugs, and that it plays an important role in the pathogenesis of intestinal inflammation. To test this hypothesis, the following specific aims are proposed: Aim 1. To determine the in situ intestinal transport properties of peptide-like drugs (and prodrugs), bacterially-derived peptides, and anti- inflammatory tripeptides; Aim 2. To characterize the in vivo absorption and disposition of peptide-like drugs (and prodrugs), and anti-inflammatory tripeptides; and Aim 3. To evaluate the role and relevance of PEPT1 in mediating the inflammatory response to bacterially-derived peptides and anti-inflammatory tripeptides. By combining cellular/tissue, molecular, and whole animal studies in wild-type and PEPT1 null mice, the proposed studies will greatly advance our understanding of the in vivo role, significance and vectorial transport of peptides, peptide-like drugs (and prodrugs) by PEPT1 (as opposed to other transporters and/or passive processes). Moreover, our findings will provide important new insights into the mechanisms of PEPT1- mediated intestinal inflammation and, as a result, identify a new target for therapeutic strategies against inflammatory bowel disease. Finally, the proposed studies may offer rare insight into the variability of peptide/mimetic kinetics and response in those human subjects with genetic polymorphisms.