Wang Yuqing, Sun Dongli, Song Feifeng, Hu Yongjun, Smith David E, Jiang Huidi
Laboratory of Pharmaceutical Analysis and Drug Metabolism, Zhejiang Province Key Laboratory of Anti-Cancer Drug Research, College of Pharmaceutical Sciences, Zhejiang University , Hangzhou, Zhejiang 310058, P. R. China.
Mol Pharm. 2014 Jun 2;11(6):1880-8. doi: 10.1021/mp500014r. Epub 2014 May 2.
Membrane transporter PhT2 (SLC15A3), which belongs to the proton-coupled oligopeptide transporter family, mediates the transport of di/tripeptides and histidine utilizing an inwardly directed proton gradient and negative membrane potential. The aim of this study was to elucidate the molecular expression of PhT2 in macrophages and mouse tissues and to explore the regulation of PhT2 by lipopolysaccharide (LPS). The results showed relatively high expression of PhT2 in J774A.1 and THP-1 macrophage cells, mouse spleen, and lung. Using an LPS-induced inflammatory cell model, we found that hPhT2 mRNA expression was up-regulated in THP-1 cells and that the up-regulation was suppressed by pyrrolidine dithiocarbamate, a specific inhibitor of NF-κB. Similar results were observed in mouse spleen during LPS-induced acute inflammation. Using dual-labeling immunofluorescence and confocal laser scanning microscopy, we confirmed that mPhT2 was colocalizing with lysosome-associated membrane protein 1 in transfected HEK293 cells. These results suggested that PhT2, a lysosomal membrane transporter, was up-regulated by LPS via the NF-κB signaling pathway.
膜转运蛋白PhT2（SLC15A3）属于质子偶联寡肽转运蛋白家族，利用内向质子梯度和负膜电位介导二肽/三肽和组氨酸的转运。本研究的目的是阐明PhT2在巨噬细胞和小鼠组织中的分子表达，并探讨脂多糖（LPS）对PhT2的调节作用。结果显示，PhT2在J774A.1和THP-1巨噬细胞、小鼠脾脏和肺中表达相对较高。利用LPS诱导的炎性细胞模型，我们发现THP-1细胞中hPhT2 mRNA表达上调，且该上调被NF-κB的特异性抑制剂吡咯烷二硫代氨基甲酸盐抑制。在LPS诱导的急性炎症过程中，小鼠脾脏也观察到类似结果。利用双标免疫荧光和共聚焦激光扫描显微镜，我们证实转染的HEK293细胞中mPhT2与溶酶体相关膜蛋白1共定位。这些结果表明，溶酶体膜转运蛋白PhT2通过NF-κB信号通路被LPS上调。
