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Functional expression and differential localization of epithelial sodium channel δ subunit isoforms
Author(s) -
de la Rosa Diego Alvarez,
AfonsoOramas Domingo,
CruzMuros Ignacio,
GonzalezHernandez Tomas,
Giraldez Teresa
Publication year - 2007
Publication title -
the faseb journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.709
H-Index - 277
eISSN - 1530-6860
pISSN - 0892-6638
DOI - 10.1096/fasebj.21.6.lb101-c
Subject(s) - epithelial sodium channel , xenopus , acid sensing ion channel , gene isoform , amiloride , protein subunit , ion channel , sodium channel , microbiology and biotechnology , chemistry , central nervous system , biology , receptor , endocrinology , biochemistry , sodium , gene , organic chemistry
Proteins of the ENaC/DEG family of non‐voltage gated Na + channels are widely expressed in the central and peripheral nervous system. This family includes acid sensing ion channels, which are thought to be involved in certain sensory modalities in the PNS and in modulation of learning and memory in the brain. Another branch of the ENaC/DEG family includes epithelial Na + channels (ENaCs), which mediate amiloride‐sensitive Na + transport across epithelia. ENaC subunits expression has also been documented in the nervous system, but their functional roles remain poorly studied. Others and we have recently cloned a new isoform of the human ENaC δ subunit (ENaC δ2). Expression of δ2 in Xenopus oocytes failed to induce amiloride‐inhibitable Na + currents. In contrast, when δ2 was co‐expressed with ENaC accessory subunits (β and γ), an amiloride‐sensitive Na + current was detected. δ2βγ produced ten‐fold less current than the classical αβγ ENaC channel, due to low expression at the plasma membrane, suggesting that the physiological partners of δ2 might be ENaC/DEG proteins other than β and γ. In situ hybridization showed that both δ isoforms are prominently expressed in pyramidal neurons of the human cortex. Double‐labeling experiments demonstrated a low level of co‐localization between isoforms, suggesting distinct functional roles in the human CNS. Supported by grant BFU2004‐04433 (Ministerio de Educación y Ciencia, Spain)