BC3H-1 분화세포에서의 (Na,K)ATPase alpha2 isoform의 표현증대

Increased Expression of the alpha2 Isoform of (Na,K)ATPase in the Differentiated Murine Muscle Cell Line BC3H-1

The development of the alpha2 isoform of (Na,K)ATPase which is high affinity ouabain receptors was studied in the differentiating nonfusing muscle cell line BC3H-1. The differentiation process of BC3H-1 cell line was confirmed by 2-dexy-D-[3H] glucose uptake experiment and the quantity of the expression of alpha2 isoform was measured using a whole cell [3H] ouabain-binding assay. Undifferentiated growing BC3H-1 cells, myoblasts, exhibited low levels of insulin-stimulated glucose uptake and [3H] ouabain-binding sites. In contrast, differentiated BC3H-1 cells, myocytes, had a 5.6-fold increase in insulin-stimulated glucose uptake and 5-fold increase in [3H] ouabain-binding sites. Scatchard analysis showed that myocytes developed more [3H] ouabain-binding sites than myoblasts vath a dissociation constant (kd) of 6X1O-8M and capacity of 6.lX1O5 sites/cell. Therefore. it seems that myoblasts express low levels of alpha2 subunit and probably the majority of alpha1 subunit, whereas myocytes express high levels of alpha2 isoform. The results indicate that the expression of alpha2 isoform is developmentally regulated during differentiation and that BC3H-1 culture system provides an excellent model for the study of differentiation and mechanism of (Na,K)ATPase action in muscle which requires electrical excitability.