Open AccessMummichog gill and operculum exhibit functionally consistent claudin-10 paralog profiles and Claudin-10c hypersaline response
Author(s) -
Chun-Chih Chen,
William S. Marshall,
George N. Robertson,
Regina R. F. Cozzi,
Scott P. Kelly
Publication year - 2021
Publication title -
biology open
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.936
H-Index - 41
ISSN - 2046-6390
DOI - 10.1242/bio.058868
Subject(s) - claudin , biology , microbiology and biotechnology , tight junction , paracellular transport , western blot , planarian , osmotic concentration , genetics , biochemistry , gene , membrane , permeability (electromagnetism) , regeneration (biology)
Claudin (Cldn)-10 tight junction (TJ) proteins are hypothesized to form the paracellular Na+ secretion pathway of hyposmoregulating mummichog (Fundulus heteroclitus) branchial epithelia. Organ-specific expression profiles showed that only branchial organs [the gill and opercular epithelium (OE)] exhibited abundant cldn-10 paralog transcripts, which typically increased following seawater (SW) to hypersaline (2SW) challenge. Post-translational properties, protein abundance, and ionocyte localization of Cldn-10c, were then examined in gill and OE. Western blot analysis revealed two Cldn-10c immunoreactive bands in the mummichog gill and OE at ∼29 kDa and ∼40 kDa. The heavier protein could be eliminated by glycosidase treatment, demonstrating the novel presence of a glycosylated Cldn-10c. Protein abundance of Cldn-10c increased in gill and OE of 2SW-exposed fish. Cldn-10c localized to the sides of gill and OE ionocyte apical crypts and partially colocalized with cystic fibrosis transmembrane conductance regulator and F-actin, consistent with TJ complex localization. Cldn-10c immunofluorescent intensity increased but localization was unaltered by 2SW conditions. In support of our hypothesis, cldn-10/Cldn-10 TJ protein dynamics in gill and OE of mummichogs and TJ localization are functionally consistent with the creation and maintenance of salinity-responsive, cation-selective pores that facilitate Na+ secretion in hyperosmotic environments.