Plasma membrane-bound sialidase NEU3 modulates clathrin-mediated endocytosis

RODRIGUEZ WALKER M.; VILCAES A.; DANIOTTI J.L.

Rosario

Congreso; 50 Reunión anual de la Sociedad Argentina de Investigación en Bioquímica y Biología Molecular (SAIB); 2014

Sociedad Argentina de Investigación en Bioquímica y Biología Molecular (SAIB)

Gangliosides are sialic acid containing glycosphingolipids mainly expressed at the plasma membrane. Sialidase NEU3 is a key enzyme in the catabolism of gangliosides and its up-regulation has been observed in cancer cells. In the case of clathrin-mediated endocytosis (CME), although this has been widely studied, the role of NEU3 and gangliosides in this cellular process has not yet been well established. Here, we found an increased internalization of transferrin (Tf), the archetypical cargo for CME, in cells expressing complex gangliosides with high levels of sialylation. The ectopic expression of NEU3 led to a drastic decrease in Tf endocytosis, suggesting a participation of gangliosides in this process. However, the expression of NEU3 in ganglioside-depleted cells only slightly affected its inhibition on Tf endocytosis. Additionally, the internalization of LDL, another typical ligand in CME, was also decreased in NEU3 overexpressing cells. In contrast, cholera toxin β-subunit internalization, which occurs by both clathrin-dependent and clathrin-independent mechanisms, remained unaltered. NEU3 overexpressing cells showed an altered subcellular distribution of clathrin adaptor AP-2, but did not reveal any changes in the membrane distribution of clathrin, phosphatidylinositol 4, 5-bisphosphate or caveolin-1. Overall, these results suggest a specific and novel role of NEU3 in CME.