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A genome-wide CRISPR screen reconciles the role of N-linked glycosylation in galectin-3 transport to the cell surface.

Accepted version
Peer-reviewed

Type

Article

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Authors

Stewart, Sarah E 
Menzies, Sam A 
Popa, Stephanie J 
Savinykh, Natalia 
Petrunkina Harrison, Anna 

Abstract

Galectins are a family of lectin binding proteins expressed both intracellularly and extracellularly. Galectin-3 (Gal-3, also known as LGALS3) is expressed at the cell surface; however, Gal-3 lacks a signal sequence, and the mechanism of Gal-3 transport to the cell surface remains poorly understood. Here, using a genome-wide CRISPR/Cas9 forward genetic screen for regulators of Gal-3 cell surface localization, we identified genes encoding glycoproteins, enzymes involved in N-linked glycosylation, regulators of ER-Golgi trafficking and proteins involved in immunity. The results of this screening approach led us to address the controversial role of N-linked glycosylation in the transport of Gal-3 to the cell surface. We find that N-linked glycoprotein maturation is not required for Gal-3 transport from the cytosol to the extracellular space, but is important for cell surface binding. Additionally, secreted Gal-3 is predominantly free and not packaged into extracellular vesicles. These data support a secretion pathway independent of N-linked glycoproteins and extracellular vesicles.

Description

Keywords

Galectin, Glycosylation, Unconventional secretion, Blood Proteins, CRISPR-Cas Systems, Endoplasmic Reticulum, Galectin 3, Galectins, Genome-Wide Association Study, Glycosylation, Golgi Apparatus, HeLa Cells, Humans, Protein Transport

Journal Title

J Cell Sci

Conference Name

Journal ISSN

0021-9533
1477-9137

Volume Title

130

Publisher

The Company of Biologists
Sponsorship
Medical Research Council (MC_UU_12012/5)
Medical Research Council (MC_UU_12012/1)
Wellcome Trust (101835/Z/13/Z)
Wellcome Trust (100574/Z/12/Z)
Medical Research Council (MC_PC_12012)