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Adaptation of Murine Inner Medullary Collecting Duct (IMCD3) Cell Cultures to Hypertonicity
Author(s) -
CAPASSO JUAN M.,
RIVARD CHRISTOPHER J.,
ENOMOTO LAURA M.,
BERL TOMAS
Publication year - 2003
Publication title -
annals of the new york academy of sciences
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.712
H-Index - 248
eISSN - 1749-6632
pISSN - 0077-8923
DOI - 10.1111/j.1749-6632.2003.tb07222.x
Subject(s) - downregulation and upregulation , gamma subunit , ly294002 , protein subunit , g alpha subunit , biology , microbiology and biotechnology , messenger rna , beta (programming language) , cell culture , signal transduction , chemistry , pi3k/akt/mtor pathway , biochemistry , gene , computer science , programming language , genetics
A bstract : Recently, we have adapted IMCD3 cell cultures to survive under increasing hypertonic conditions (i.e., 600 and 900 mOsmol/kg H 2 O). In adapted cells, ATPase activity is increased by one order of magnitude, while the expression of the α and β subunit is increased by a factor of 4 to 5 over controls (300 mOsmol/kg H 2 O). Corresponding increases in mRNAs were also detected. The γ subunit has been described as being uniquely expressed in some areas of the kidney, but never in cell cultures (even those derived from kidney tissues). However, the γ subunit was detected at the protein and mRNA levels in the adapted IMCD3 cells. In contrast to the α and β subunits, the levels of γ protein and mRNA expression continue to increase as a function of the media ion concentration. We have also demonstrated that signaling pathways that upregulate the α, β, and γ subunits are very different. Increasing concentrations of the PI3 kinase inhibitor, LY294002, resulted in a dose‐dependent reduction in the expression of the γ subunit, with total abolition at 10 μM. However, LY294002 had no significant effect on the expression of the α subunit. Inhibition of the JNK2 (but not of the JNK1) pathways by dominant negative transfections abolished the upregulation of the γ, but not the a subunit. Failure to upregulate the expression of the γ subunit was associated with a marked decrease in cell viability upon stress.