Inhibition of cell spreading in CHO cells transfected with cDNA of a glycosylphosphatidyl inositol-anchored protein, GPI-80

We have previously cloned a glycosylphosphatidyl inositol (GPI)-anchored protein, designated GPI-80 that associated with integrin and may modulate leukocyte adherence and migration. Recent studies have shown that GPI-80 belongs to a Vanin family that is related to pantetheinase, but the regulatory function of GPI-80 in cell adherence is still unclear. To clarify the possible functions of GPI-80, we transfected GPI-80 cDNA into Chinese hamster ovary (CHO) cells and observed adherence and morphological changes. Adherence of GPI-80 transfectants was significantly decreased when signal strength for the cell adhesion is weak, and the cell spreading of the transfectants was strongly inhibited. This inhibitory effect of GPI-80 expression was largely canceled by GPI-80 shedding with phosphatidylinositol-specific phospholipase C. Interestingly, spreading of GPI-80 transfectants was temporarily recovered from the round shape but not maintained by stimulation with known activators of β1 integrins, phorbol myristate acetate and manganese ions. Taken together, these results suggest that the expression of GPI-80 on CHO cells can influence cell spreading in weak adhesive signal conditions via extracellular matrix molecules.