Expression and function of PEPT2 during transdifferentiation of alveolar epithelial cells
Expression and function of PEPT2 during transdifferentiation of alveolar epithelial cells
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PEPT2在肺泡上皮细胞转分化过程中的表达及功能
DOI：
10.1016/j.lfs.2013.08.008
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发表时间：
2013
期刊：
影响因子：
6.1
通讯作者：
R.
中科院分区：
文献类型：
--
作者：
Takano;M.;Horiuchi;T.;Sasaki;Y.;Kato Y.;Nagai;J. and Yumoto;R.
目的探讨肽转运蛋白2（PEPT 2）在原代培养肺泡Ⅱ型上皮细胞和转分化的类Ⅰ型上皮细胞中的表达和功能。关键发现从大鼠肺分离的II型细胞中PEPT 2 mRNA的表达在第0天最高，并且在细胞培养期间迅速下降。根据这种变化，PEPT 2活性估计为头孢羟氨苄敏感性[3 H]Gly-Sar摄取也沿着转分化降低。免疫组化和Western blot分析证实PEPT 2蛋白在II型细胞中的表达。[3 H]Gly-Sar在II型细胞中的摄取具有时间和pH依赖性。相反，在I型样细胞中观察到最小的时间依赖性和无pH依赖性的[3 H]Gly-Sar摄取。最大的[3 H]Gly-Sar摄取在pH 6.0时观察到，和摄取在较高的pH值在II型细胞下降。头孢羟氨苄浓度依赖性地抑制Ⅱ型细胞摄取[~ 3 H]Gly-Sar，IC_（50）值为4.3 μM。另一方面，在I型样细胞中未观察到头孢羟氨苄的显著抑制作用。此外，Ⅱ型细胞对[3 H]Gly-Sar的摄取是饱和的，Km值为72.0 μ M。意义PEPT 2在肺泡Ⅱ型上皮细胞中有功能性表达，但表达沿着分化而降低，而在Ⅰ型细胞中PEPT 2几乎完全丧失。
AimsThe purpose of this study was to clarify the expression and function of peptide transporter 2 (PEPT2) in primary cultured alveolar type II epithelial cells and in transdifferentiated type I-like cells.Main methodsReal-time PCR analysis, uptake study of [3H]Gly-Sar, and immunostaining were performed in alveolar epithelial cells.Key findingsThe expression of PEPT2 mRNA in type II cells isolated from rat lungs was highest at day 0, and decreased rapidly during culture of the cells. In accordance with this change, PEPT2 activity estimated as cefadroxil-sensitive [3H]Gly-Sar uptake also decreased along with transdifferentiation. The expression of PEPT2 protein in type II cells was confirmed by immunostaining and Western blot analysis. The uptake of [3H]Gly-Sar in type II cells was time- and pH-dependent. In contrast, minimal time-dependence and no pH-dependence of [3H]Gly-Sar uptake were observed in type I-like cells. The maximal [3H]Gly-Sar uptake was observed at pH 6.0, and the uptake decreased at higher pHs in type II cells. The uptake of [3H]Gly-Sar in type II cells was inhibited by cefadroxil in a concentration-dependent manner, the IC50value being 4.3 μM. On the other hand, no significant inhibition by cefadroxil was observed in type I-like cells. In addition, [3H]Gly-Sar uptake in type II cells was saturable, the Km value being 72.0 μM.SignificancePEPT2 is functionally expressed in alveolar type II epithelial cells, but the expression decreases along with transdifferentiation, and PEPT2 would be almost completely lost in type I cells.