title: Expression and trafficking of the gamma subunit of Na,K-ATPase in hypertonically challenged IMCD3 cells.
abstract: The gamma subunit (FXYD2) of Na,K-ATPase is an important regulator of the sodium pump. In this investigation we have analysed the trafficking of gamma to the plasma membrane in cultures of inner medullary collecting duct cells (IMCD3) following acute hypertonic challenge and brefeldin A (BFA) treatment. Following hypertonic challenging for 24 hr immunofluorescence labeling revealed initial co-localization of the gamma subunit and 58K Golgi protein in the cytoplasm, but no co-localization of alpha1 and Golgi protein. Exposure of the challenged cells to BFA prevented the subsequent incorporation of gamma into the basolateral plasma membrane. The gamma subunit instead remained in cytoplasmic vesicles while cell proliferation and cell viability decreased simultaneously. Following removal of BFA from the hypertonic medium the IMCD3 cells recovered with distinct expression of gamma in the basolateral membrane. The alpha1 subunit was only marginally influenced by BFA. The results demonstrate that the gamma subunit trafficks to the plasma membrane via the Golgi apparatus, despite the absence of a signal sequence. The results also suggest that the gamma and alpha subunits do not traffic together to the plasma membrane, and that the gamma and alpha subunit have different turnover rates during these experimental conditions.
authors.affiliation: Water and Salt Research Center, Department of Cell Biology, Institute of Anatomy, University of Aarhus, DK-8000 Aarhus C, Denmark. kpm@ana.au.dk
authors.forename: Kaarina
authors.initials: K
authors.lastname: Pihakaski-Maunsbach
authors.forename: Shoichi
authors.initials: S
authors.lastname: Nonaka
authors.forename: Arvid B
authors.initials: AB
authors.lastname: Maunsbach
references.citation: Sci STKE. 2003 Jan 21;2003(166):RE1
references.pmid: 12538882
references.citation: Cell. 1991 Nov 1;67(3):449-51
references.pmid: 1934055
references.citation: Am J Physiol Renal Physiol. 2001 Sep;281(3):F531-45
references.pmid: 11502602
references.citation: J Biol Chem. 1988 Dec 5;263(34):18545-52
references.pmid: 3192548
references.citation: Cell Struct Funct. 1990 Feb;15(1):31-7
references.pmid: 2340587
references.citation: Nephron Physiol. 2008;109(1):p1-10
references.pmid: 18460876
references.citation: Proc Natl Acad Sci U S A. 1994 Jun 7;91(12):5686-9
references.pmid: 8202549
references.citation: Am J Physiol. 1997 Jun;272(6 Pt 1):C1781-9
references.pmid: 9227405
references.citation: Proc Natl Acad Sci U S A. 2001 Nov 6;98(23):13414-9
references.pmid: 11687620
references.citation: J Biol Chem. 2003 Sep 12;278(37):34794-803
references.pmid: 12826673
references.citation: Annu Rev Cell Dev Biol. 2003;19:333-66
references.pmid: 14570573
references.citation: Am J Physiol. 1992 Apr;262(4 Pt 1):C845-53
references.pmid: 1314489
references.citation: J Cell Biol. 1996 Jun;133(6):1193-204
references.pmid: 8682858
references.citation: J Cell Biol. 1991 Jun;113(5):1009-23
references.pmid: 1710224
references.citation: Annu Rev Physiol. 2006;68:431-59
references.pmid: 16460279
references.citation: Traffic. 2005 Sep;6(9):794-802
references.pmid: 16101682
references.citation: Am J Physiol Renal Physiol. 2005 Apr;288(4):F650-7
references.pmid: 15572522
references.citation: Am J Physiol Renal Physiol. 2006 Nov;291(5):F1033-44
references.pmid: 16757733
references.citation: FEBS Lett. 1990 Aug 20;269(1):105-8
references.pmid: 2167238
references.citation: Genomics. 2000 Aug 15;68(1):41-56
references.pmid: 10950925
references.citation: J Biol Chem. 1989 Sep 25;264(27):16083-92
references.pmid: 2777777
references.citation: J Biol Chem. 2000 Jun 16;275(24):18441-6
references.pmid: 10748024
references.citation: J Histochem Cytochem. 2002 Dec;50(12):1611-23
references.pmid: 12486083
references.citation: Am J Physiol. 1992 Feb;262(2 Pt 1):C470-83
references.pmid: 1311503
references.citation: J Cell Biol. 1997 Dec 15;139(6):1545-52
references.pmid: 9396759
references.citation: J Cell Biol. 1992 Mar;116(5):1071-80
references.pmid: 1740466
references.citation: Mol Cell Biol. 1989 Dec;9(12):5742-5
references.pmid: 2555706
references.citation: J Biol Chem. 1990 Feb 25;265(6):3528-34
references.pmid: 2154482
references.citation: J Biol Chem. 2001 Jun 8;276(23):20370-8
references.pmid: 11278761
references.citation: Nature. 2002 May 9;417(6885):187-93
references.pmid: 12000962
references.citation: Am J Physiol Cell Physiol. 2001 Sep;281(3):C982-92
references.pmid: 11502575
references.citation: Ann N Y Acad Sci. 2003 Apr;986:410-5
references.pmid: 12763858
references.citation: FEBS Lett. 1992 Jul 27;307(1):93-6
references.pmid: 1639200
references.citation: J Bioenerg Biomembr. 2007 Dec;39(5-6):373-8
references.pmid: 17972022
references.citation: News Physiol Sci. 2003 Jun;18:119-24
references.pmid: 12750449