Choi Janghan, Li Weiqi, Schindell Brayden, Ni Liju, Liu Shangxi, Zhao Xiaoya, Gong Joshua, Nyachoti Martin, Yang Chengbo
Department of Animal Science, University of Manitoba, Winnipeg, MB, R3T 2N2, Canada.
Shanghai Lab-Animal Research Center, Shanghai, 201203, China.
Anim Nutr. 2020 Mar;6(1):107-114. doi: 10.1016/j.aninu.2019.10.001. Epub 2019 Oct 31.
The cystine/glutamate exchanger (xCT, SLC7A11) is a component of the system X amino-acid antiporter that is able to export glutamate and import cysteine into cells. The xCT amino acid exchanger has received a lot of attention, due to the fact that cysteine is an essential substrate for the synthesis of glutathione (GSH), an endogenous antioxidant in cells. The objective of this research was to clone the full-length cDNA of chicken xCT, and to investigate the gene expression of xCT in different tissues, including intestinal segments of broiler chickens during development. The full-length cDNA of chicken xCT (2,703 bp) was obtained from the jejunum by reverse transcription-PCR and sequenced. Homology tests showed that chicken xCT had 80.4%, 80.2%, and 71.2% homology at the nucleotide level with humans, cattle, and rats, respectively. Likewise, amino acid sequence analysis showed that chicken xCT protein is 86.4%, 79.3%, and 75.6% homologous with humans, cattle, and rats, respectively. Additionally, phylogenetic analysis indicated that chicken xCT genes share a closer genetic relationship with humans and cattle, than with rats. The chicken xCT protein has 12 transmembrane helixes, 6 extracellular loops, and 5 intracellular loops. The mRNA of xCT was detected in all tissues, including intestinal segments, in which the mRNA expression of xCT was significantly higher ( < 0.05) within the colon, compared to the jejunum and ileum. During development, a linear pattern of changes regarding the levels of the xCT mRNA was found, indicating that there was an abundance of xCT within the duodenum ( < 0.05). Furthermore, there were changes of the xCT mRNA abundance in the colon during development, which displayed linear and cubic patterns ( < 0.05). These results indicated that xCT is widely expressed both in intestinal segments, as well as other organs that are not associated with nutrient absorption. Further investigation is needed to characterize the functional relevance of xCT activity in oxidative stress and inflammation in the small intestine of broiler chickens.
胱氨酸/谷氨酸交换体（xCT，SLC7A11）是系统X氨基酸反向转运体的一个组成部分，它能够将谷氨酸输出细胞，并将半胱氨酸输入细胞。xCT氨基酸交换体受到了广泛关注，因为半胱氨酸是细胞内源性抗氧化剂谷胱甘肽（GSH）合成的必需底物。本研究的目的是克隆鸡xCT的全长cDNA，并研究xCT在不同组织中的基因表达，包括肉鸡发育过程中的肠道各段。通过逆转录PCR从空肠中获得鸡xCT的全长cDNA（2703 bp）并进行测序。同源性测试表明，鸡xCT在核苷酸水平上与人类、牛和大鼠的同源性分别为80.4%、80.2%和71.2%。同样，氨基酸序列分析表明，鸡xCT蛋白与人类、牛和大鼠的同源性分别为86.4%、79.3%和75.6%。此外，系统发育分析表明，鸡xCT基因与人类和牛的遗传关系比与大鼠的更近。鸡xCT蛋白有12个跨膜螺旋、6个细胞外环和5个细胞内环。在所有组织中都检测到了xCT的mRNA，包括肠道各段，其中结肠中xCT的mRNA表达水平显著高于空肠和回肠（P<0.05）。在发育过程中，发现xCT mRNA水平呈线性变化模式，表明十二指肠中xCT含量丰富（P<0.05）。此外，发育过程中结肠中xCT mRNA丰度发生变化，呈现线性和三次方模式（P<0.05）。这些结果表明，xCT在肠道各段以及其他与营养吸收无关的器官中广泛表达。需要进一步研究来确定xCT活性在肉鸡小肠氧化应激和炎症中的功能相关性。
