Research On The Movement Of Cell-Bound Membrane Vesicles On The Cell Surface Under Different Conditions

In recent years,a nonreleasing novel vesicle has been found on the cell surface.At present,the composition,structure,production,movement,fate,and function of the cell-bound membrane vesicles are poorly understood.Cell spreading and migration are two important activities of cells.This thesis speculates that the production and movement of cell-bound membrane vesicles may be different under different conditions.Therefore,we analyzed the cell-bound membrane vesicles under different conditions via single-vesicle tracking.First,under the condition of cell spreading,the expression of intercellular adhesion molecule(ICAM-1)in both protein and mRNA levels in HUVECs increased after stimulation with OxLDL,TNF-?,VEGF,and LPS,respectively.The data demonstrate that these stimuli could cause cellular activation.M?CD could significantly remove cholesterol from the plasma membrane of cells,thereby changing the fluidity of the plasma membrane.Single-vesicle tracking revealed that OxLDL,TNF-?,and VEGF could significantly increase the average number and the average speed of cell-bound membrane vesicles but not the displacement(moving range).Second,under the condition of cell migration,the stimulation of HUVECs by Ang-1,OxLDL,TNF-?,VEGF,and LPS induced the significant increases in expression level of Rho A(an important,migration-related type of Rho GTPases)and in migration mobility of cells,certifying that these reagents could promote cell migration.Further single-vesicle tracking study found that OxLDL,TNF-?,and Ang-1 could significantly increase the average number of cell-bound membrane vesicles and that OxLDL,TNF-?,LPS,Ang-1,and VEGF could significantly increase the average speed of cell-bound membrane vesicles whereas OxLDL significantly expanded the displacement.In order to further investigate the relationship between cytoskeleton and cell-bound membrane vesicles,Cytochalasin D and Nocodazole were utilized to destroyed the microfilaments and microtubules(two types of cytoskeleton),respectively,and then single-vesicle tracking analysis was performed.It was found that under both conditions(i.e.cell spreading and migration),cytoskeleton disruption could significantly increase the number of cell-bound membrane vesicles but significantly decrease their speed and displacement.The results imply that the production and movement of cell-bound membrane vesicles are closely related with the cytoskeleton.In summary,the production and movement of cell-bound membrane vesicles may be affected by a variety of cell activities(such as activation,membrane fluidity,spreading,and migration,etc.)and probably regulated by the cytoskeleton.This study provides important implications for understanding the production and movement of cell-bound membrane vesicles on cells.