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Epithelial Sodium Channel and Acid Sensing Ion Channel Subunits Interact With Each Other To Play A Role In Glioblastoma Whole Cell Current
Author(s) -
Kapoor Niren,
Bartoszewski Rafal,
Fuller Catherine M,
Palmer Cheryl A,
Benos Dale J
Publication year - 2009
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.23.1_supplement.1000.4
Subject(s) - epithelial sodium channel , amiloride , acid sensing ion channel , patch clamp , ion channel , immunocytochemistry , hek 293 cells , sodium channel , chemistry , immunoprecipitation , transfection , protein subunit , microbiology and biotechnology , electrophysiology , biology , medicine , endocrinology , sodium , biochemistry , receptor , gene , organic chemistry
High grade gliomas like glioblastoma (GBM) characteristically display a basally active amiloride sensitive cation current not seen in normal human astrocytes. We hypothesize this current to be mediated by a hybrid channel composed of a mixture of Epithelial Sodium Channel (ENaC)/ Degenerins (Deg) subunits. Using semi‐quantitative RT‐PCR we have shown higher expression of ASIC1, αENaC, and γENaC in primary GBM cells compared to primary human astrocytes. We have also shown the expression of these subunits in GBM biopsies and on the plasma membrane of GBM cells using immunocytochemistry. To test our hypothesis we made dominant negative (DN) cDNAs for ASIC1, αENaC, γENaC, and δENaC. D54‐MG cells transfected with the DN constructs for ASIC1, αENaC or γENaC showed 50‐ 70% reduction in protein expression and significant inhibition of whole cell patch clamp current compared with untransfected D54‐MG. Knocking down δENaC in D54‐MG cells reduced δENaC protein expression by 50%, but had no effect on the whole cell patch clamp current. Using co‐immunoprecipitation we show interactions between ASIC1, αENaC, and γENaC, consistent with these subunits interacting with each other to form an ion channel in glioma cells. These data suggest that different ENaC/Deg subunits combine to form a hybrid channel that likely underlies the amiloride‐sensitive current in human gliomas. This study was supported by NIH Grant CA101952.