Wang Jin-Lin, Zhao Lei, Zhu Jun, Wang Deng-Ke, Ren Mei-Juan, Wang Meng, Liu Ying, Boron Walter F, Chen Li-Ming
Key Laboratory of Molecular Biophysics of the Ministry of Education, School of Life Science and Technology, Huazhong University of Science and Technology, Wuhan, China.
Department of Obstetrics, Maternal and Child Health Hospital of Hubei Province, Wuhan, China.
Front Physiol. 2019 Oct 29;10:1334. doi: 10.3389/fphys.2019.01334. eCollection 2019.
The electroneutral Na/HCO cotransporter NBCn2 (SLC4A10) of solute carrier family 4 (SLC4) plays important physiological and pathological roles in the body. Our previous study showed that NBCn2 is expressed on the protein level in the small intestine of rat. Here, by reverse-transcription polymerase chain reaction (PCR), we identified a novel full-length NBCn2 variant, i.e., NBCn2-K, from rat small intestine. By pH measurement with oocytes, the activity of NBCn2-K is not significantly different from NBCn2-G. By western blotting, NBCn2 and the Na/H exchanger NHE3 (SLC9A3) are predominantly expressed in the jejunum of rat small intestine. By immunofluorescence, NBCn2 and NHE3 are localized at the apical domain of the jejunum. NaCl overload decreases the expression of NBCn2 by 56% and that of NHE3 by 40% in the small intestine. We propose that NBCn2 is involved in the transepithelial NaCl absorption in the small intestine, and that the down-regulation of NBCn2 by NaCl represents an adaptive response to high salt intake in rat.
溶质载体家族4（SLC4）的电中性钠/碳酸氢根共转运体NBCn2（SLC4A10）在机体中发挥着重要的生理和病理作用。我们之前的研究表明，NBCn2在大鼠小肠中存在蛋白表达。在此，通过逆转录聚合酶链反应（PCR），我们从大鼠小肠中鉴定出一种新的全长NBCn2变体，即NBCn2-K。通过卵母细胞pH测量，NBCn2-K的活性与NBCn2-G无显著差异。通过蛋白质印迹法，NBCn2和钠/氢交换体NHE3（SLC9A3）主要在大鼠小肠空肠中表达。通过免疫荧光法，NBCn2和NHE3定位于空肠的顶端区域。氯化钠过载使小肠中NBCn2的表达降低56%，NHE3的表达降低40%。我们认为，NBCn2参与小肠上皮氯化钠的吸收，并且氯化钠导致的NBCn2下调是大鼠对高盐摄入的一种适应性反应。
