Vimentin affects localization and activity of sodium-glucose cotransporter SGLT1 in membrane rafts.
It has been reported that vimentin, a cytoskeleton filament that is expressed only in mesenchymal cells after birth, is re-expressed in epithelial cells in vivo under pathological conditions and in vitro in primary culture. Whether vimentin re-expression is only a marker of cellular dedifferentiation or is instrumental in the maintenance of cell structure and/or function is a matter of debate. To address this issue, we used renal proximal tubular cells in primary culture from vimentin-null mice (Vim(-/-)) and from wild-type littermates (Vim(+/+)). The absence of vimentin did not affect cell morphology, proliferation and activity of hydrolases, but dramatically decreased Na-glucose cotransport activity. This phenotype was associated with a specific reduction of SGLT1 protein in the detergent-resistant membrane microdomains (DRM). In Vim(+/+) cells, disruption of these microdomains by methyl-beta-cyclodextrin decreased SGLT1 protein abundance in DRM, a change that was paralleled by a decrease of Na-glucose transport activity. Importantly, we showed that vimentin is located to DRM, but it disappeared after methyl-beta-cyclodextrin treatment. In Vim(-/-) cells, supplementation of cholesterol with cholesterol-methyl-beta-cyclodextrin complexes completely restored Na-glucose transport activity. Interestingly, neither cholesterol content nor cholesterol metabolism changed in Vim(-/-) cells. Our results are consistent with the view that re-expression of vimentin in epithelial cells could be instrumental to maintain the physical state of rafts and, thus, the function of DRM-associated proteins.
Runembert
Isabelle
I
INSERM U426 and Department Physiology, Faculté de Médecine Xavier Bichat, IFR 02, Université Paris 7, Paris, France.
Queffeulou
Guillaume
G
Federici
Pierre
P
Vrtovsnik
François
F
Colucci-Guyon
Emma
E
Babinet
Charles
C
Briand
Pascale
P
Trugnan
Germain
G
Friedlander
Gérard
G
Terzi
Fabiola
F
D000818:Animals; D001692:Biological Transport; D002454:Cell Differentiation; D002455:Cell Division; D002478:Cells, Cultured; D002784:Cholesterol / Q000378:metabolism; D003505:Cyclodextrins / Q000494:pharmacology; D003902:Detergents / Q000378:metabolism; D005947:Glucose / Q000378:metabolism; D006867:Hydrolases / Q000378:metabolism; D007687:Kidney Tubules, Proximal / Q000737:chemistry / Q000166:cytology / Q000378:metabolism*; D008562:Membrane Glycoproteins / Q000032:analysis* / Q000378:metabolism*; D021962:Membrane Microdomains / Q000737:chemistry / Q000187:drug effects / Q000378:metabolism*; D051379:Mice; D018345:Mice, Knockout; D009004:Monosaccharide Transport Proteins / Q000032:analysis* / Q000378:metabolism*; D009924:Organ Culture Techniques; D012964:Sodium / Q000378:metabolism; D051269:Sodium-Glucose Transporter 1; D014746:Vimentin / Q000235:genetics / Q000502:physiology*; D047392:beta-Cyclodextrins
D003505:Cyclodextrins; D003902:Detergents; D008562:Membrane Glycoproteins; D009004:Monosaccharide Transport Proteins; C495675:Slc5a1 protein, mouse; D051269:Sodium-Glucose Transporter 1; D014746:Vimentin; D047392:beta-Cyclodextrins; C108732:methyl-beta-cyclodextrin; D002784:Cholesterol; D012964:Sodium; D006867:Hydrolases; D005947:Glucose