The first extracellular domain of claudin-7 affects paracellular Cl- permeability

被引:75
作者
Alexandre, Michele D. [1 ]
Jeansonne, Beverly G. [1 ]
Renegar, Randall H. [1 ]
Tatum, Rodney [1 ]
Chen, Yan-Hua [1 ]
机构
[1] E Carolina Univ, Sch Med, Dept Anat & Cell Biol, Greenville, NC 27834 USA
关键词
claudin-7; tight junctions; paracellular charge selectivity; dilution potentials; Cl-; permeability; LLC-PK1; cells;
D O I
10.1016/j.bbrc.2007.03.078
中图分类号
Q5 [生物化学]; Q7 [分子生物学];
学科分类号
071010 ; 081704 ;
摘要
Tight junctions (TJ) constitute paracellular diffusion channels regulating the passage of ions and Solutes across epithelia. We recently demonstrated that overexprcssion of the TJ membrane protein claudin-7 in LLC-PK1 cells decreases paracellular permeability to Cl- and increases paracellular permeability to Na+. To investigate the effect of charged amino acid residues in extracellular domains (ED) of claudin-7 on paracellular charge selectivity, we created claudin-7 mutants by replacing negatively charged amino acids on ED with positively charged amino acids. Immunofluorescence light microscopy showed that these mutant proteins were correctly targeted to the cell junction. Ultrastructure examination of TJ morphology did not reveal any difference between cells expressing wildtype (WT) and mutant claudin-7. However, electrophysiological studies showed increased Cl- permeability in cells expressing first extracellular domain (ED1) mutants, but not second extracellular domain (ED2) mutants, compared to that of WT claudin-7. Our results demonstrate that negatively charged amino acids in ED1 of claudin-7 are involved in modulating paracellular Cl- permeability. (c) 2007 Elsevier Inc. All rights reserved.
引用
收藏
页码:87 / 91
页数:5
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