Samenvatting

Phosphorylation of serine180 and serine204 activates receptor protein tyrosine phosphatase alpha (RPTP) which dephosphorylates and activates the protein Src kinase. Active Src phosphosphorylates downstream focal adhesion kinases and other substrates of Src which affects the motility and so on the migration of the cells.

We were interested in the role of serine phosphorylation in regulation of receptor protein tyrosine phosphatase alpha and the effect on cell motility. To find out if serine phosphorylation have an effect and which serine residue of RPTP cause this effect on the cell motility we did a wound-healing migration assay and time-lapse video microscopy to record the movement of cells during migration. Using software, we determined the migration rate of cells expressing single and double serine180 or serine204 mutated RPTP. Individual cell trajectory data resulted in a decreased cell migration in serine204 to alanine mutants in mouse embryonal fibroblast cells compared to RPTP knock-out cells and an increase in serine180 to alanine mutant RPTP cells. Also we found a decreased migration rate in wildtype RPTP cells compared to RPTP knock-out cells. The decreasing in migration rate which was also found in double serine180/serine204 to alanine mutants has indicated that absence of serine204 leads to a reduction in the motility of cells.
According to this data, we may suggest that serine204 dephosphorylation activates RPTP and so leads to migration of cells.