Mammalian proteins are highly glycosylated, especially on cell surfaces. Cell-surface glycans are involved in a number of biological functions. Thus, the importance of live cell surface-based N-glycan editing is self-evident. Focusing on cell surface engineering over years, Creative Biolabs has accumulated extensive experience from practice. With rich experience and strong foundations, we are capable of offering high-quality live-cell surface-based N-glycan editing services to global customers.
Fig.1 Diagram of cell surface glycans. (Briard, 2018)
Mammalian proteins are highly glycosylated, and protein glycosylation, the most common post-translation modification, is involved in many biological events, especially on cell surfaces. Cell-surface glycosylation involves N-glycans, O-glycans, glycosylphosphatidylinositol anchors, glycosaminoglycans, glycolipids, and so on. N-glycans (the main form of protein glycosylation) comprise various structural subtypes, including high-mannose, complex, hybrid, core-fucosylated, non-core-fucosylated, and bisecting types, among others. Cell-surface glycans are involved in a number of biological functions, including cell-cell communication, membrane protein trafficking, pathogen invasion, and immune response. The pursuit of well-defined N-glycosylation at the cellular level requires a constructive strategy.
Researchers have discovered a series of CHO N-glycosylation mutants with lectin resistances, in which glycosyltransferase levels change and affect N-glycan biosynthesis, producing N-glycan structures with less heterogeneity. A similar concept of glycosyltransferase engineering has been applied in the glycoengineering of therapeutic glycoproteins. In a FUT8 knockout CHO cell line or a glycoengineered Pichia pastoris expression system, immunoglobulin-G (IgG) antibodies bearing optimized N-glycan structures were produced with enhanced anti-tumor efficacy. This strategy provided a useful tool to control the N-glycosylation of secreted proteins or membrane proteins.
Selective editing and labeling of specific monosaccharides on cell surfaces via chemical biology techniques, such as metabolic glycan labeling, selective oxidation, and glycosyltransferase-catalyzed modification, has gradually been established. Selective oxidation of monosaccharides with a chemical oxidant or oxidase provides an alternate strategy to label cell-surface glycans. By chemical biology techniques, many remarkable works achieve cell-surface glycan labeling and living cell imaging, focusing on the selective detection of monosaccharides or disaccharides.
ENGase-catalyzed N-glycosylation remodeling is an emerging technique for the preparation of homogeneous glycoproteins that have been developed substantially over the past decade. Wild-type (WT) ENGases cleave the GlcNAcβ1,4GlcNAc motif of the N-glycan core and remove native heterogeneous glycoforms, then the ENGase mutants reassemble a homogeneous synthetic N-glycan substrate onto the pretreated glycoprotein carrying the innermost GlcNAc. The application of this method in Lec4 CHO mutant cells achieved a less-heterogeneous-to-homogeneous strategy of glycan editing, which will be greatly beneficial for the exploration of the precise glycan-associated functions of membrane glycoproteins.
As a global leading CRO company, Creative Biolabs has rich experience in cell surface engineering and has accomplished hundreds of relevant projects. Based on these conditions, we are capable of providing high-quality live-cell surface-based N-glycan editing services.
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