Background
Yes Associated Protein (YAP) has been found to differentially regulate cell growth and proliferation based on cell shape and matrix stiffness by altering the level of its phosphorylation. We hypothesized that different types of flow have different effects on the phosphorylation of YAP.

Objective
The aim of this study was to assess the level of phosphorylation of YAP when subjected to pulsatile forward flow(PFF), analogous to uniform flow, or pulsatile To Fro Flow (TFF), analogous to disturbed flow

Material and Methods
Confluent human umbilical vein endothelial cells (HUVECs) seeded on fibronectin coated glass slides were exposed to TFF and PFF in a parallel plate flow chamber controlled by a computerized pump for up to 4 hours at 37 ̊ C in a humidified CO2 environment. HUVECs incubated in culture medium under static conditions served as control. At the end of experimentation, cell lysates were prepared and immunobloted with antibodies to phospho-YAP and total YAP .

Result
HUVECs exposed to both TFF and PFF showed a decrease in the phosphorylation of YAP when compared to static controls. The degree of decrease in phosphorylation was more with PFF when compared with TFF.

Conclusion
Different types of flow have different effects on phosphorylation of YAP. These results suggest that YAP could be a mechano-transducer for endothelial cells. Since differences in flow types have been postulated to be play a role in atherogenesis, these results also suggest the possibility of involvement of YAP in atherosclerosis.