Xiang Jianming, Chiang Pei-Pei, Hu Yongjun, Smith David E, Keep Richard F
Department of Neurosurgery, University of Michigan, 1500 East Medical Center Drive, R5550 Kresge I, Ann Arbor, 48109-0532, USA.
Neurosci Lett. 2006 Apr 3;396(3):225-9. doi: 10.1016/j.neulet.2005.11.037. Epub 2005 Dec 20.
The aims of the current study were (1) to quantify the role of PEPT2 in the uptake of glycylsarcosine (GlySar) in cultured neonatal astrocytes and (2) to examine GlySar transport and PEPT2 expression in two glioma cell lines. The uptake of [(14)C]GlySar was measured in astrocytes cultured from neonatal mouse (PEPT2(+/+) and PEPT2(-/-)) and rat, as well as rat C6 and F98 glioma cells. PEPT2 expression was examined by reverse transcription-polymerase chain reaction (RT-PCR). Neonatal astrocytes from PEPT2(-/-) mice had a 94% reduction in [(14)C]GlySar uptake compared to wild type mice and there was no saturable transport. In PEPT2(+/+) mice, [(14)C]GlySar uptake was saturable (V(max) 58 +/- 12 pmol/mg/min, K(m) 107 +/- 46 microM, K(d) 0.043 +/- 0.004 microl/mg/min). In neonatal rat astrocytes, kinetic analysis also suggested that [(14)C]GlySar uptake was via a single transporter. The inhibitor profile and pH dependence of that transport process was consistent with PEPT2. In C6 and F98 glioma cells, [(14)C]GlySar uptake was markedly reduced ( approximately 96-98%) compared to that in neonatal astrocytes and this was reflected by an absence of PEPT2 mRNA expression. These results indicate that PEPT2 is the sole transporter involved in the uptake of GlySar into neonatal cultured astrocytes. However, PEPT2 mRNA appears to be absent from two glioma cell lines.
（1）量化肽转运体2（PEPT2）在培养的新生星形胶质细胞摄取甘氨酰肌氨酸（GlySar）中的作用；（2）检测两种胶质瘤细胞系中GlySar的转运及PEPT2的表达。采用新生小鼠（PEPT2(+/+)和PEPT2(-/-)）及大鼠培养的星形胶质细胞，以及大鼠C6和F98胶质瘤细胞，检测[(14)C]GlySar的摄取。通过逆转录-聚合酶链反应（RT-PCR）检测PEPT2的表达。与野生型小鼠相比，PEPT2(-/-)小鼠的新生星形胶质细胞[(14)C]GlySar摄取减少了94%，且不存在饱和转运。在PEPT2(+/+)小鼠中，[(14)C]GlySar摄取具有饱和性（V(max) 58±12 pmol/mg/min，K(m) 107±46 microM，K(d) 0.043±0.004 microl/mg/min）。在新生大鼠星形胶质细胞中，动力学分析也表明[(14)C]GlySar摄取是通过单一转运体进行的。该转运过程的抑制剂谱和pH依赖性与PEPT2一致。在C6和F98胶质瘤细胞中，[(14)C]GlySar摄取与新生星形胶质细胞相比显著降低（约96 - 98%），这反映在PEPT2 mRNA表达缺失上。这些结果表明，PEPT2是新生培养星形胶质细胞摄取GlySar的唯一转运体。然而，两种胶质瘤细胞系中似乎均不存在PEPT2 mRNA。
