EAAT3 promotes amino acid transport and proliferation of porcine intestinal epithelial cells

// Jin-ling Ye 1, * , Chun-qi Gao 1, * , Xiang-guang Li 1, * , Cheng-long Jin 1 , Dan Wang 1 , Gang Shu 1 , Wen-ce Wang 1 , Xiang-feng Kong 2 , Kang Yao 2 , Hui-chao Yan 1 , Xiu-qi Wang 1 1 College of Animal Science, South China Agricultural University/National Engineering Research Center for Breeding Swine Industry, Guangzhou, Guangdong Province, China 2 Institute of Subtropical Agriculture, Chinese Academy of Sciences, Changsha, Hunan Province, China * These authors have contributed equally to this work Correspondence to: Xiu-qi Wang, email: xqwang@scau.edu.cn Keywords: excitatory amino acid transporter 3, mammalian target of rapamycin, intestinal epithelial cells, amino acid, proliferation Received: February 12, 2016     Accepted: April 29, 2016     Published: May 25, 2016 ABSTRACT Excitatory amino acid transporter 3 (EAAT3, encoded by SLC1A1 ) is an epithelial type high-affinity anionic amino acid transporter, and glutamate is the major oxidative fuel for intestinal epithelial cells. This study investigated the effects of EAAT3 on amino acid transport and cell proliferation through activation of the mammalian target of the rapamycin (mTOR) pathway in porcine jejunal epithelial cells (IPEC-J2). Anionic amino acid and cystine (Cys) transport were increased ( P <0.05) by EAAT3 overexpression and decreased ( P <0.05) by EAAT3 knockdown rather than other amino acids. MTT and cell counting assays suggested that IPEC-J2 cell proliferation increased ( P <0.05) with EAAT3 overexpression. Phosphorylation of mTOR (Ser2448), ribosomal protein S6 kinase-1 (S6K1, Thr389) and eukaryotic initiation factor 4E-binding protein-1 (4EBP1, Thr70) was increased by EAAT3 overexpression and decreased by EAAT3 knockdown ( P <0.05), as were levels of activating transcription factor 4 (ATF4) and cystine/glutamate antiporter (xCT) ( P <0.05). Our results demonstrate for the first time that EAAT3 facilitates anionic amino acid transport and activates the mTOR pathway, promoting Cys transport and IPEC-J2 cell proliferation.