Targeted disruption of the PEPT2 gene markedly reduces dipeptide uptake in choroid plexus
Targeted disruption of the PEPT2 gene markedly reduces dipeptide uptake in choroid plexus
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DOI：
10.1074/jbc.m207397200
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发表时间：
2003-02-14
影响因子：
4.8
通讯作者：
Brosius, FC
中科院分区：
文献类型：
--
作者：
Shen, H;Smith, DE;Brosius, FC
大脑中多种寡肽转运蛋白的存在引起了人们对它们在神经肽稳态中的生理作用、药理学重要性以及作为穿过血脑和血脑脊液屏障的药物递送靶标的潜力的极大兴趣。为了进一步了解特定肽转运蛋白在大脑中的用途，我们通过靶向基因破坏产生了 PEPT2 缺陷小鼠。纯合子 PepT2 缺失小鼠在脉络丛和肾脏（PepT2 正常表达的组织）中缺乏 PEPT2 mRNA 和蛋白质的表达，而杂合子小鼠表现出的 PepT2 表达水平介于野生型和纯合子缺失动物之间。突变型 PepT2 缺失小鼠被发现能够存活，生长至正常大小和体重，并且没有明显的肾脏或大脑异常。尽管缺乏明显的生物效应，分离的脉络丛中质子刺激的 1.9 mum 甘氨酰肌氨酸（一种模型，耐水解二肽）的摄取基本上被消除（即，5 分钟和 30 分钟时的残余活性分别为 10.9% 和 3.9%）。这些新发现提供了强有力的证据，证明在本研究的实验条件下，PEPT2是负责脉络丛组织中二肽摄取的肽转运蛋白家族的主要成员。
The presence of multiple oligopeptide transporters in brain has generated considerable interest as to their physiological role in neuropeptide homeostasis, pharmacologic importance, and potential as a target for drug delivery through the blood-brain and blood-cerebrospinal fluid barriers. To understand further the purpose of specific peptide transporters in brain, we have generated PEPT2-deficient mice by targeted gene disruption. Homozygous PepT2 null mice lacked expression of PEPT2 mRNA and protein in choroid plexus and kidney, tissues in which PepT2 is normally expressed, whereas heterozygous mice displayed PepT2 expression levels that were intermediate between those of wild-type and homozygous null animals. Mutant PepT2 null mice were found to be viable, grew to normal size and weight, and were without obvious kidney or brain abnormalities. Notwithstanding the lack of apparent biological effects, the proton-stimulated uptake of 1.9 mum glycylsarcosine (a model, hydrolysis-resistant dipeptide) in isolated choroid plexus was essentially ablated (ie. residual activity of 10.9 and 3.9% at 5 and 30 min, respectively). These novel findings provide strong evidence that, under the experimental conditions of this study, PEPT2 is the primary member of the peptide transporter family responsible for dipeptide uptake in choroid plexus tissue.