Title: FXYD2 and Na,K-ATPase Expression in Isolated Human Proximal Tubular Cells: Disturbed Upregulation on Renal Hypomagnesemia?
Authors: Cairo, Edinio R ×
Swarts, Herman G P
Wilmer, Martijn J G
Willems, Peter H G M
Levtchenko, Elena
De Pont, Jan Joep H H M
Koenderink, Jan B #
Issue Date: Oct-2009
Publisher: Springer-Verlag New York
Series Title: Journal of Membrane Biology vol:231 issue:2-3 pages:117-124
Abstract: Autosomal dominant renal hypomagnesemia (OMIM 154020), associated with hypocalciuria, has been linked to a 121G to A mutation in the FXYD2 gene. To gain insight into the molecular mechanisms linking this mutation to the clinical phenotype, we studied isolated proximal tubular cells from urine of a patient and a healthy subject. Cells were immortalized and used to assess the effects of hypertonicity-induced overexpression of FXYD2 on amount, activity and apparent affinities for Na(+), K(+) and ATP of Na,K-ATPase. Both cell lines expressed mRNA for FXYD2a and FXYD2b, and patient cells contained both the wild-type and mutated codons. FXYD2 protein expression was lower in patient cells and could be increased in both cell lines upon culturing in hyperosmotic medium but to a lesser extent in patient cells. Similarly, hyperosmotic culturing increased Na,K-ATPase protein expression and ATP hydrolyzing activity but, again, to a lesser extent in patient cells. Apparent affinities of Na,K-ATPase for Na(+), K(+) and ATP did not differ between patient and control cells or after hyperosmotic induction. We conclude that human proximal tubular cells respond to a hyperosmotic challenge with an increase in FXYD2 and Na,K-ATPase protein expression, though to a smaller absolute extent in patient cells.
ISSN: 0022-2631
Publication status: published
KU Leuven publication type: IT
Appears in Collections:Section Child - Miscellaneous (-)
× corresponding author
# (joint) last author

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