A Research About The Phosphorylation Influence Of LKB1/NUAK1 On Pten In Hela Cells

NUAK1 (novel (nua) kinase family 1) and LKB1 (liver kinase B1) are both kinases. PTEN (phosphatase and tensin homolog deleted on chromosome ten) is a phosphorylase. NUAK1 is one of the downstream substrates of LKB 1 kinase, and it can be activated by phosphorylatory role of LKB1. Studies have shown that the phosphorylation regulatory role of LKB 1 on other proteins (such as p53 and tuberin) are both mediated by NUAK1. In addition, another study has shown that the presence of co-localization and interaction between LKB 1 and PTEN. But for both with direct interaction, or mediated by other factors have not been reported. Hence, we propose a prediction that PTEN can be regulated by LKB1 through NUAK1 mediating. This paper will focus on the phosphorylation impact of LKB 1 on PTEN. The study have found after the reconstruction of LKB1 expression in HeLa cells, NUAK1 can co-immunoprecipitate with PTEN, suggesting that there may be a direct interaction between NUAK1 and PTEN in the presence of wild-type LKB1. Further experiments on the phosphorylation of PTEN have shown that under glucose deprivation in the cells, the wild-type LKB1 significantly activates the kinase activity of NUAKl. The activated NUAK1 can significantly increases the phosphorylation level of PTEN. It is NUAK1 siRNA pool that interfering the expression of NUAK1, almost reduce the phosphorylation of PTEN to a zero level. These results have shown that LKB1 implements the phosphorylation regulation of PTEN by activating NUAKl, its further step with down-regulation of mTOR pathway and inhibition of protein synthesis and proliferation of cells.