| Autor: |
Racine, Ronny R., Manalo, Nathan A., Hall, Jessica M.F., Dibas, Adnan, Raffel, Glen D., Mummert, Mark E. |
| Zdroj: |
Biochemistry and Biophysics Reports; July 2016, Vol. 6 Issue: 1 p172-178, 7p |
| Abstrakt: |
The purpose of this study was to investigate how CD44 impaired Akt phosphorylation, EGR-1 expression and cell proliferation. E6.1 Jurkat cells, which lack endogenous CD44 expression, were engineered to express CD44. Previously we showed that Akt is hypophosphorylated, EGR-1 expression is reduced and proliferation is impaired in CD44 expressing E6.1 Jurkat cells. The cell cycle was studied using flow cytometry and the role of calcium (Ca2+) in Akt phosphorylation and EGR-1 expression was investigated using Western blotting. Phosphatase activity was assessed using a commercially available kit. CD44 expressing cells showed disruption at the G1to S transition. Chelation of Ca2+from the culture media impaired Akt phosphorylation and EGR-1 expression in both CD44 expressing cells and the open vector control. Moreover, Ni2+disrupted cell proliferation in both cell types suggesting Ca2+import through calcium release activated calcium channels (CRAC). Staining of cells with fura-2 AM showed significantly higher Ca2+in CD44 expressing cells as compared with the vehicle control. Finally, non-calcium mediated phosphatase activity was significantly greater in CD44 expressing cells. We propose that the enhanced phosphatase activity in the CD44 cells increased the dephosphorylation rate of Akt; at the same time, the increased intracellular concentration of Ca2+in the CD44 cells ensured that the phosphorylation of Akt remains intact albeit at lower concentrations as compared with the vector control. Reduced Akt phosphorylation resulted in lowered expression of EGR-1 and hence, reduced the cell proliferation rate. |
| Databáze: |
Supplemental Index |
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