(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.

Agency
National Institute of Health (NIH)
Institute
National Institute of General Medical Sciences (NIGMS)
Type
Research Project (R01)
Project #
5R01GM035498-10
Application #
6635930
Study Section
Special Emphasis Panel (ZRG1-CVB (03))
Program Officer
Okita, Richard T
Project Start
1988-02-01
Project End
2005-03-31
Budget Start
2003-04-01
Budget End
2004-03-31
Support Year
10
Fiscal Year
2003
Total Cost
$248,578
Indirect Cost
Name
University of Michigan Ann Arbor
Department
Pharmacology
Type
Schools of Pharmacy
DUNS #
073133571
City
Ann Arbor
State
MI
Country
United States
Zip Code
48109
Xie, Yehua; Hu, Yongjun; Smith, David E (2016) The proton-coupled oligopeptide transporter 1 plays a major role in the intestinal permeability and absorption of 5-aminolevulinic acid. Br J Pharmacol 173:167-76
Xie, Yehua; Shen, Hong; Hu, Yongjun et al. (2016) Population pharmacokinetic modeling of cefadroxil renal transport in wild-type and Pept2 knockout mice. Xenobiotica 46:342-9
Hu, Yongjun; Xie, Yehua; Keep, Richard F et al. (2014) Divergent developmental expression and function of the proton-coupled oligopeptide transporters PepT2 and PhT1 in regional brain slices of mouse and rat. J Neurochem 129:955-65
Wang, Yuqing; Sun, Dongli; Song, Feifeng et al. (2014) Expression and regulation of the proton-coupled oligopeptide transporter PhT2 by LPS in macrophages and mouse spleen. Mol Pharm 11:1880-8
Hu, Yongjun; Xie, Yehua; Wang, Yuqing et al. (2014) Development and characterization of a novel mouse line humanized for the intestinal peptide transporter PEPT1. Mol Pharm 11:3737-46
Zheng, G; Wu, S-P; Hu, Y et al. (2013) Corticosterone mediates stress-related increased intestinal permeability in a region-specific manner. Neurogastroenterol Motil 25:e127-39
Posada, Maria M; Smith, David E (2013) In vivo absorption and disposition of cefadroxil after escalating oral doses in wild-type and PepT1 knockout mice. Pharm Res 30:2931-9
Yang, Bei; Hu, Yongjun; Smith, David E (2013) Impact of peptide transporter 1 on the intestinal absorption and pharmacokinetics of valacyclovir after oral dose escalation in wild-type and PepT1 knockout mice. Drug Metab Dispos 41:1867-74
Huh, Yeamin; Keep, Richard F; Smith, David E (2013) Impact of lipopolysaccharide-induced inflammation on the disposition of the aminocephalosporin cefadroxil. Antimicrob Agents Chemother 57:6171-8
Posada, Maria M; Smith, David E (2013) Relevance of PepT1 in the intestinal permeability and oral absorption of cefadroxil. Pharm Res 30:1017-25

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