Na+, K+-ATPase genes are down-regulated during adipose stem cell differentiation.

The expression of Na+, K+-ATPase alpha and beta subunits isoforms, FXYD2 and FXYD7 were studied in rat adipose stem cell (ASC) by qRT-PCR and immunofluorescence. ASCs were able to differentiate to chondrocytes or adipocytes. All studied genes were expressed in freshly isolated ASCs and in all passages checked. Immunostaining for alpha1 isoform was found in plasma membrane and nuclear envelope, alpha2 signal was lower and alpha3 staining was variable among cells. Beta isoforms signal was abundant and displayed an isoform-specific picture. Staining for FXYD7 was homogeneous in plasma membrane and cytosol. Chondrocytes differenciated from ASC showed identical Na+, K+-ATPase subunits isoforms expression patterns to chondrocytes in cartilage. The expression pattern of Na+, K+-ATPase genes in ASCs exhibits a unique phenotypic signature that implies functional differences in Na+ and K+ transport rates. Furthermore, this phenotypic signature may also be used as a complementary marker for studies of mesenchymal stem cell differentiation. We propose a possible 'moonlighting' role of Na+, K+-ATPase beta isoforms that could be essential for the study of mesenchymal stem cell function and differentiation.