Co-Expression of NEU2 and GBA3 Causes a Drastic Reduction in Cytosolic Sialyl Free N-glycans in Human MKN45 Stomach Cancer Cells-Evidence for the Physical Interaction of NEU2 and GBA3

Biomolecules. 2015 Jul 16;5(3):1499-514. doi: 10.3390/biom5031499.

Li Wang ¹, Junichi Seino ², Haruna Tomotake ³ ⁴, Yoko Funakoshi ⁵, Hiroto Hirayama ⁶, Tadashi Suzuki ⁷ ⁸

Affiliations

1 Glycometabolome Team, Systems Glycobiology Research Group, RIKEN-Max Planck Joint Research Center for Systems Chemical Biology, RIKEN Global Research Cluster, Saitama 351-0198, Japan. wangli0909@gmail.com.
2 Glycometabolome Team, Systems Glycobiology Research Group, RIKEN-Max Planck Joint Research Center for Systems Chemical Biology, RIKEN Global Research Cluster, Saitama 351-0198, Japan. jseino@riken.jp.
3 Glycometabolome Team, Systems Glycobiology Research Group, RIKEN-Max Planck Joint Research Center for Systems Chemical Biology, RIKEN Global Research Cluster, Saitama 351-0198, Japan. haruna.tomotake@riken.jp.
4 Graduate School of Science and Engineering, Saitama University, Saitama 338-8570, Japan. haruna.tomotake@riken.jp.
5 Glycometabolome Team, Systems Glycobiology Research Group, RIKEN-Max Planck Joint Research Center for Systems Chemical Biology, RIKEN Global Research Cluster, Saitama 351-0198, Japan. yfunakos@sbigroup.co.jp.
6 Glycometabolome Team, Systems Glycobiology Research Group, RIKEN-Max Planck Joint Research Center for Systems Chemical Biology, RIKEN Global Research Cluster, Saitama 351-0198, Japan. hiroto-hirayama@riken.jp.
7 Glycometabolome Team, Systems Glycobiology Research Group, RIKEN-Max Planck Joint Research Center for Systems Chemical Biology, RIKEN Global Research Cluster, Saitama 351-0198, Japan. tsuzuki_gm@riken.jp.
8 Graduate School of Science and Engineering, Saitama University, Saitama 338-8570, Japan. tsuzuki_gm@riken.jp.

PMID: 26193330 DOI: 10.3390/biom5031499

Abstract

It is well known that the "free" form of glycans that are structurally related to asparagine (N)-linked glycans ("free N-glycans") are found in a wide variety of organisms. The mechanisms responsible for the formation/degradation of high mannose-type free N-glycans have been extensively studied in mammalian cells. Recent evidence, however, also suggests that sialylated, complex-type free N-glycans are also present in the cytosol of various mammalian-derived cultured cells/tissues. We report herein on an investigation of the mechanism responsible for the degradation of such sialyl free N-glycans. The findings show that the amount of glycans is dramatically reduced upon the co-expression of cytosolic sialidase NEU2 with cytosolic β-glycosidase GBA3 in human stomach cancer-derived MKN45 cells. The physical interaction between NEU2 and GBA3 was confirmed by co-precipitation analyses as well as gel filtration assays. The NEU2 protein was found to be stabilized in the presence of GBA3 both in cellulo and in vitro. Our results thus indicate that cytosolic GBA3 is likely involved in the catabolism of cytosolic sialyl free N-glycans, possibly by stabilizing the activity of the NEU2 protein.

Keywords

GBA3; NEU2; free N-glycans; glycan catabolism; sialyl oligosaccharides.

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