Role of GOLPH3 in the physical and functional association of ganglioside glycosyltransferases at the Golgi complex

RUGGIERO FERNANDO MIGUEL; RODRIGUEZ-WALKER MACARENA; CAVIERES VIVIANA ; MARDONES GONZALO; DANIOTTI JOSE LUIS

Buenos Aires

Simposio; Third Argentinian Symposium on Glycobiology; 2019

UNSAM, IBYME, CIQUIBIC, IHEM, FIL

Golgi phosphoprotein 3 (GOLPH3) localizes to the Golgi complex. Several studies have shown that GOLPH3 modulates protein glycosylation. Glycolipids are also part of the glycocalyx of the cells. Changes in the glycosylation of these lipids were reported in many physiological as well as pathological conditions. However, is not known if GOLPH3 is involved in this regulation. To study the potential role of GOLPH3 in the metabolism of glycolipids, 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 with an upregulation of GM1 gangliosides 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. Moreover, ST3Gal-II and 3GalT-IV were physically associated in CHO-K1 cells and GOLPH3 was part of this complex. In vivo association of ST3Gal-II and 3GalT-IV also occurred in T98G cells, but this interaction was decreased in T98G KD cells. Thus, GOLPH3 levels correlate with the expression of complex gangliosides in T98G cells. 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, may result in a dysregulation of ganglioside synthesis at the Golgi complex.