Open AccessClaudin-10isoform expression and cation selectivity change with salinity in salt-secreting epithelia ofF. heteroclitus
Author(s) -
William S. Marshall,
Jason P. Breves,
Ellen M. Doohan,
Christian K. Tipsmark,
Scott P. Kelly,
George N. Robertson,
Patricia M. Schulte
Publication year - 2017
Publication title -
journal of experimental biology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.367
H-Index - 185
eISSN - 1477-9145
pISSN - 0022-0949
DOI - 10.1242/jeb.168906
Subject(s) - claudin , biology , euryhaline , chemistry , microbiology and biotechnology , salinity , tight junction , ecology
To provide insight into claudin (Cldn) tight junction (TJ) protein contributions to branchial salt secretion in marine teleost fishes, this study examined cldn-10 TJ protein isoforms of a euryhaline teleost (mummichog; Fundulus heteroclitus) in association with salinity change and measurements of transepithelial cation selectivity. Mummichogs were transferred from fresh water (FW) to seawater (SW, 35 ‰) and from SW to hypersaline SW (2SW, 60 ‰) in a time course with transfer control groups (FW to FW and SW to SW). FW to SW transfer increased mRNA abundance of cldn-10d and -10e by 2-fold, whilst cldn-10c and -10f transcripts were unchanged. Transfer from SW to 2SW did not alter cldn-10d, and transiently altered cldn-10e abundance, but increased cldn-10c and -10f by 4-fold. This was coincident with an increased number of single-stranded junctions (observed by TEM). For both salinity transfers; (1) cldn-10e mRNA was acutely responsive (i.e. after 24 h), (2) other responsive cldn-10 isoforms increased later (3-7 days), and (3) cystic fibrosis transmembrane conductance regulator (cftr) mRNA was elevated in accordance with established changes in transcellular Cl− movement. Changes in mRNA encoding cldn-10c and -10f appeared linked, consistent with the tandem repeat locus in the Fundulus genome, whereas mRNA for tandem cldn-10d and -10e seemed independent of each other. Cation selectivity sequence measured by voltage and conductance responses to artificial SW revealed Eisenman sequence VII: Na+>K+>Rb+∼Cs+>Li+. Collectively, these data support the idea that Cldn-10 TJ proteins create and maintain cation-selective pore junctions in salt-secreting tissues of teleost fishes.