Carrier-mediated sulfate transport in human ureteral epithelial cells cultured in serum-free medium.
Carrier-mediated sulfate transport in human ureteral epithelial cells cultured in serum-free medium.
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在无血清培养基中培养的人输尿管上皮细胞中载体介导的硫酸盐转运。
DOI：
10.1152/ajpcell.1991.261.5.c916
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发表时间：
1991
期刊：
影响因子：
--
通讯作者：
Debro,L
中科院分区：
文献类型：
--
作者：
Elgavish,A;Wille,JJ;Rahemtulla,F;Debro,L
硫酸盐转运研究是在分离自人输尿管上皮细胞的二次培养中进行的。结果表明，载体介导的SO4(2-)转运的存在得到了三条证据的支持：1)饱和动力学，2)底物特异性，3)阴离子转运抑制剂4，4‘-二异硫氰基二苯乙烯-2，2’-二磺酸(DIDS)的抑制作用。DIDS不敏感的SO4(2-)转运组分明显低于DIDS敏感组分，且不受胞外pH(Pho)或Cl-浓度变化的影响。这种DDS不敏感成分的作用机制尚不清楚。胞外硫酸盐浓度([SO4(2-)]o)是胞外SO4(2-)摄取的可饱和函数。胞外氯浓度([Cl-]o)的增加竞争性地抑制了对DIDS敏感的SO4(2-)的摄取。这些结果提示，尿路上皮细胞对SO4(2-)的摄取是通过SO4(2-)-Cl-阴离子交换实现的。对多种阴离子的顺式抑制研究表明，该阴离子交换体系可能与S2O_3(2-)和MoO_4(2-)共享，而与NO_3~-和H_2PO_4~-不共享。降低pho可刺激对SO4(2-)的吸收，pK约为7.4。将pho从7降低到6，显著降低了表观米氏常数，但对kcat没有显著影响，表明质子可能增加了SO4(2-)转运体对SO4(2-)的亲和力。SO4(2-)外流在低pho时被抑制，而在增加[Cl-]o时被刺激。本研究首次证实了人输尿管上皮细胞培养上皮细胞的离子转运过程。与上尿路上皮细胞相比，这些下尿路上皮细胞不存在Na(+)依赖的SO4(2-)转运。综上所述，输尿管上皮细胞SO4(2-)转运的主要机制是载体介导的、DDS敏感的、光敏的SO4(2-)/Cl-阴离子交换机制。这些研究表明，输尿管管腔中不同的[SO4(2-)]o和[Cl-]o或pho会影响SO4(2-)的流入和流出，并可能影响这些细胞内可用于大分子硫酸盐化的SO4(2-)池的大小。
Sulfate transport studies were carried out in secondary cultures of epithelial cells isolated from the human ureter. Results demonstrate the presence of carrier-mediated SO4(2-) transport as supported by three lines of evidence: 1) saturation kinetics, 2) substrate specificity, and 3) inhibition by the anion transport inhibitor 4,4'-diisothiocyanostilbene-2,2'-disulfonic acid (DIDS). The DIDS-insensitive component of SO4(2-) transport was markedly lower than the DIDS-sensitive component and was not affected by changes in extracellular pH (pHo) or Cl- concentration. The mechanism of this DIDS-insensitive component is not clear. The DIDS-sensitive component of SO4(2-) uptake was a saturable function of the extracellular sulfate concentration ([SO4(2-)]o). Increasing the extracellular chloride concentration ([Cl-]o) inhibited DIDS-sensitive SO4(2-) uptake competitively. Taken together with the fact that increasing [Cl-]o stimulated SO4(2-) efflux, these results suggest that SO4(2-) uptake in uroepithelial cells occurs via SO4(2-)-Cl- anion exchange. Cis-inhibition studies with a variety of anions indicate that this anion-exchange system may be shared by S2O3(2-) and MoO4(2-) but not by NO3- and H2PO4-. SO4(2-) uptake was stimulated at decreasing pHo with a pK approximately 7.4. Decreasing pHo from 7 to 6 lowered the apparent Michaelis constant significantly but had no significant effect on kcat, suggesting that protons may increase the affinity of the SO4(2-) transporter for SO4(2-). SO4(2-) efflux was inhibited at low pHo and was stimulated by increasing [Cl-]o. This study is the first to demonstrate an ion transport process in epithelial cell cultures isolated from the human ureter. In contrast to epithelial cells from the upper urinary tract, no Na(+)-dependent SO4(2-) transport could be demonstrated in these lower urinary tract epithelial cells. In conclusion, the major mechanism for SO4(2-) transport in ureteral epithelial cells is a carrier-mediated, DIDS-sensitive, pHo-sensitive SO4(2-)/Cl- anion-exchange mechanism. These studies suggest that varying [SO4(2-)]o and [Cl-]o or pHo in the ureteral lumen will affect SO4(2-) influx and efflux and may influence the size of the intracellular pool of SO4(2-) available for macromolecular sulfation in these cells.
影响因子：
5
作者：
CHACE, KV;LEAHY, DS;SACHDEV, GP
通讯作者：
SACHDEV, GP