Insulin rapidly stimulates ERK2 in the membrane of osteoblast-like UMR-106 cell

We investigated subcellular distribution of ERK2 in osteoblast-like UMR-106 cell and explored to determine if its activities are regulated by insulin. 23%, 34% and 43% of total ERK2 were distributed in membrane, cytosol and nucleus, respectively. Insulin caused 40% increase of ERK2 content in membrane in 10 min whereas it induced approximately 50% decrease of ERK2 in cytosol in 10 min. In terms of kinase activity, insulin stimulated phosphorylation of the membrane-associated ERK2 by 2-fold and 1.8-fold in 1 min and 10 min and cytosolic ERK2 by 2.7-fold and 2.3-fold in 1 min and 10 min, respectively. In contrast, the phosphorylation of nuclear ERK2 was stimulated by insulin in time-dependent manner with maximal (3-fold) activity observed at 30 min. Insulin also increased the content of MEK2 in membrane by 2.2- to 2.6-fold in 10 min. MEK2 translocated into mambrane in response to insulin may play a role in the activation of the membrane-associated ERK2 via phosphorylation.