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

Jin-Ling Ye,Chun-Qi Gao,Kang Yao,Gang Shu,Xiang-Feng Kong,Dan Wang,Xiang-Guang Li,Wen-Ce Wang,Xiu-Qi Wang,Cheng-Long Jin,Hui-Chao Yan

doi:10.18632/oncotarget.9583

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.

Highlights

Glutamate (Glu) has many important functions in nutrition, metabolism and signaling as a non-essential amino acid [1]
This study investigated the effects of excitatory amino acid transporter 3 (EAAT3) on amino acid transport and cell proliferation through activation of the mammalian target of the rapamycin pathway in porcine jejunal epithelial cells (IPEC-J2)
Our results demonstrate for the first time that EAAT3 facilitates anionic amino acid transport and activates the mammalian target of the rapamycin (mTOR) pathway, promoting Cys transport and IPEC-J2 cell proliferation

Summary

Introduction

Glutamate (Glu) has many important functions in nutrition, metabolism and signaling as a non-essential amino acid [1]. Almost all dietary Glu is extensively metabolized in first-pass by the intestine to maintain intestinal health [2,3]. Rats and mice demonstrate that the excitatory amino acid transporter 3 (EAAT3), encoded by solute carrier family 1 member 1 (SLC1A1), is the predominant anionic amino acid transporter in the intestine [5]. EAAT3 inhibition decreased pig intestinal epithelial cell (IPEC-1) proliferation [6] and intestinal growth in chick embryos [7]. Et al [8] reported that EAAT3 expression in microglia cells increased after traumatic brain injury. The mechanism of EAAT3 action in the intestine is still unclear

Methods

Results

Conclusion