Golgi phosphoprotein 3 modifies glycolipid expression by regulating the glycosylation machinery at the Golgi complex

RUGGIERO F.M.; RODRIGUEZ WALKER M.; CAVIERES V.A.; MARDONES G.A.; DANIOTTI J.L.

San Martín, Buenos Aires

Simposio; Third Argentinian Symposium on Glycobiology -GlycoAR 2019-; 2019

Third Argentinian Symposium on Glycobiology -GlycoAR 2019-

Golgi phosphoprotein 3 (GOLPH3) localizes at the Golgi complex. Several studies have shown that GOLPH3 modulates protein glycosylation. Changes in the glycosylation of glycolipids have been reported in many physiological as well as pathological conditions. However, it is unknown if GOLPH3 is involved in this regulation. To investigate the potential role of GOLPH3 in the metabolism of sialylated glycolipid (gangliosides), we generated a GOLPH3 knockdown T98G cell line (KD cells). A detailed analysis showed drastic changes in the volume and morphology of the Golgi complex, associated to a downregulation of GD1a and a concomitant upregulation of GM1 gangliosides expression at the cell surface. Also, changes in sub-Golgi localization of ST3Gal-II (GD1a synthase) but not of 3GalT-IV (GM1 synthase) were observed, while no effects were seen in N-glycosylation or N-glycan remodeling of ST3Gal-II. Interaction between ST3Gal-II and 3GalT-IV was observed in T98G cells, which significantly decreased in T98G KD cells. Interestingly, ST3Gal-II, 3GalT-IV and GOLPH3 were found to be physically associated in epithelial CHO-K1 cells. Overall, we observed that alterations in the structure of the Golgi complex, in the localization of glycosyltransferases and/or in the association between these enzymes, directly or indirectly mediated by GOLPH3, result in a dysregulation of ganglioside synthesis at the Golgi complex.