GANGLIOSIDE SYNTHESIS BY PLASMA MEMBRANE-ASSOCIATED ECTOSIALYLTRANSFERASE IN MACROPHAGES

VILCAES A.; TORRES DEMICHELIS V.A.; DANIOTTI J.L.

Córdoba

Congreso; 52 Reunión anual de la Sociedad Argentina de Investigación en Bioquímica y Biología Molecular (SAIB); 2016

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

A number of enzymes of ganglioside metabolism have been shown to be associated with the PM. In particular, it was observed in epithelial and melanoma cells that ecto-ST8Sia-I synthetize GD3 at the PM (cis-catalytic activity) and displayed enzymatic activity in PM of neighboring cells (trans-catalytic activity). Here, by biochemical and fluorescent microscopy approaches we extended these investigations to MØ and found that endogenous ecto-ST8Sia-I is present in Golgi complex as well as in PM. In addition, ecto-ST8Sia-I displayed cis-catalytic activity both in LPS-stimulated MØ and unstimulated conditions. Interestingly, LPS stimulation also reduced the ST8Sia-I levels at the PM. Besides, co-treatment of LPS with a NOs inhibitor recovered the ST8Sia-I levels, suggesting that NO formation is involved in the expression/localization of this enzyme at the PM. The enzyme levels correlated with a reduction of GD3 and GM1 and with an increment of GD1a. Moreover, the NO levels from LPS-stimulated MØ were higher in cells previously treated than in cells untreated with an inhibitor of glycolipid synthesis. The data further support the presence and activity of ecto-sialyltransferases at the PM. The variations of ecto-ST8Sia-I and gangliosides in stimulated macrophages provide a promissory information to further explore the role of this and others ganglioside metabolism-related enzymes at the PM.