Engagement of CD99 triggers the exocytic transport of ganglioside GM1 and the reorganization of actin cytoskeleton

AbstractWe studied the role of lipid rafts and actin cytoskeleton in CD99-mediated signaling to elucidate the mechanism of protein transport upon CD99 engagement. CD99 engagement in Jurkat cells elicited the exocytic transport of GM1 as well as several surface molecules closely related with CD99 functions. In addition, CD99 molecules were rapidly incorporated into lipid rafts and appeared to rearrange the actin cytoskeleton upon CD99 stimulation. Association of CD99 with actin cytoskeleton was inhibited by methyl-β-cyclodextrin, while CD99-mediated GM1 clustering was inhibited by cytochalasin D. Therefore, we suggest that CD99 may play a role in the vesicular transport of transmembrane proteins and lipid rafts from the intracellular location to the cell surface, possibly by effecting actin cytoskeleton reorganization