TMEM16F Regulates Baseline Phosphatidylserine Exposure and Cell Viability in Human Embryonic Kidney Cells

Abstract

Background / Aims: TMEM16F is a transmembrane protein from a conserved family of Ca 2+ -activated proteins, which is highly expressed in several tissues. TMEM16F confers phospholipid scramblase activity and Ca 2+ -activated electrolyte channel activity. Potentially thereby, TMEM16F is involved in cell cycle control and apoptotic signaling. The present study evaluated the role of TMEM16F on cell proliferation and viability in Human Embryonic Kidney cells. Methods: An inducible knockdown of TMEM16F was generated and markers of apoptosis and proliferation were assessed via flow cytometry, western blotting and MTT uptake assay under different conditions. Results: TMEM16F knockdown resulted in attenuated growth of HEK293 cells. This observation correlated with an increased phosphatidylserine exposure and a decreased fraction of viable cells. Interestingly, the cells were not sensitized to Staurosporine- induced cell death. Western blot analyses displayed a parallel activation of pro- and antiapoptotic signaling pathways: Caspase 3 cleavage and Cyclin D1 abundance were simultaneously increased. Furthermore, knockdown of TMEM16F led to activation of AKT signaling. Conclusion: TMEM16F modifies viability of Human Embryonic Kidney cells via its function as a phospholipid scramblase and activation of AKT signaling pathways.