Glycosylation serves essential functions on many proteins especially therapeutic antibodies produced in biopharmaceutical manufacturing, making it mandatory to thoroughly consider its biogenesis during the production process. A variety of different production platforms (such as bacteria, mammalian cells, insect cells, yeast cells, and plant cells) are currently available for recombinant glycoprotein production purposes. Powered by our advanced analytical platforms and experienced technical personnel, Creative Biolabs offers a comprehensive set of glycoprotein production system and provide a guideline for project progression.
Glycosylation is a highly complex, versatile and ubiquitous form of protein post-translational modification. Correct glycan structures are crucial for control and potency of pharmacokinetic and pharmacodynamic properties of glycoprotein biologics and therapeutic carbohydrates. Hyperglycosylated proteins show increased serum half-life, are less sensitive to proteolysis and more heat-stable compared with the non-glycosylated forms. However, protein glycosylation and synthesis of the glycosaminoglycan (GAG) portion of proteoglycans are non-templated, and thus, significant heterogeneity can arise from organism to organism, cell type to cell type, and even between different culture conditions. Different expression platforms are actively pursued by many academic and industrial laboratories. Creative Biolabs has developed five efficient systems for glycoprotein production, as follows:
Opportunities to produce glycoproteins in E. coli have been enhanced since the successful transfer of the N-linked glycosylation machinery from Campylobacter jejuni to E. coli in 2002. Two glycoprotein vaccines against Shigella dysenteriae type 1 can be produced in recombinant E. coli at a larger scale. Enzymatic synthesis of S. aureus bioconjugate vaccines in E. coli has also been reported. Glycosylation of an S. aureus surface protein with CP8 has been accomplished, and it is currently undergoing production and testing. Biosynthetic route for polysialic acid, globotriose, glycoengineered outer membrane vesicles, chondroitin sulfates in E. coli has been developed. In summary, E. coli expands the glycoengineering toolbox and provides a simpler and more robust strategy for producing bioconjugate vaccines against a variety of pathogens. Some human proteins, like adhesive glycoprotein vitronectin (VTN), human FcγRI (CD64), platelet glycoprotein VI (GPVI), soluble human erythropoietin (hEPO), human beta 2 glycoprotein I (β2GPI), and therapeutic scFv could also be produced in E. coli with functionality and characteristics.
Fig.1 Glycosylation within E. coli and major modifications leading to enhanced glycosylation efficiency (Jaffe, 2004).
Mammalian cell lines are the preferred host cell expression system to produce proteins with human-like glycosylation patterns. The main cell lines used in this platform include Chinese Hamster Ovary cells (CHO), Human Embryonic Kidney 293 cells (HEK293), Baby Hamster Kidney (BHK21), Human fibrosarcoma (HT1080) and so on. Glycoproteins such as IgG, coagulation factor VII (FVII), erythropoietin (EPO) and alpha-1 antitrypsin (A1AT) could be produced in different mammalian cells lines mentioned above. Stable 293 T and CHO cell lines could be utilized to express stable HIV-1 envelope glycoprotein trimers. Four commercial products have been produced in HEK293, B-deleted recombinant FVIII-Fc fusion protein (IgG1), B-deleted recombinant FVIII protein, recombinant FIX-IgG1 Fc fusion protein, and recombinant glucagon-1-like peptide (GLP-1) Fc fusion protein. Except for the above commercial products, many other glycoproteins such as recombinant glycodelin-A (GdA), Iduronate-2-sulfatase, agalsidase alfa, and velaglucerase alfa have also been produced by mammalian cell lines.
Fig.2 Glycoconjugates in mammalian cells (Severino, 2012).
Yeasts provide high titers recombinant glycoprotein and are easily adapted to fermentation processes in simple and cost-effective culture media. S. cerevisiae and Pichia pastoris have become a substantial workhorse for biotechnology. Using this system, a variety of glycoprotein has been produced with varying degrees of success, such as glucagon, insulin, functional recombinant rabies virus glycoprotein (RABV-G), humanized IgG1, human P-glycoprotein, ovine follicle stimulating hormone, a Hepatitis B subunit vaccine using Hepatitis B surface antigen; recombinant human granulocyte macrophage-colony stimulating factor (Leukine®), recombinant human platelet-derived growth factor (Regranex®), human papillomavirus subunit vaccine (Gardasil®), a kallikrein inhibitor (Kalbitor®), human P-glycoprotein, ovine follicle stimulating hormone and so on.
Combined with the use of baculovirus expression vector, insect expression platform can be used to rapidly produce high levels of recombinant proteins. SF9 or SF21 and BTI 5B1-4 (High Five™) are the most commonly used insect cell lines. Human 90K glycoprotein is usually produced in insect cell system. Cervarix® is a human papillomavirus (HPV) vaccine composed of a truncated form of the major capsid L1 proteins of HPV types 16 and 18 expressed in High Five™ cells. Flublok® Influenza HA vaccine is based on trivalent recombinant hemagglutinin expressed in a proprietary SF9-derived cell population. PROVENGE® is composed of a prostate surface antigen (PSA) produced in SF9 cells.
Similar to bacteria and yeast, plant cells can be easily cultured in basal culture medium and present a robust cell growth, easily scaled up. Additionally, they do not harbor human-trophic pathogens and endotoxins and are not subject to several disadvantages of recombinant glycoprotein produced in whole plants. Elelyso which is intended for the treatment of Gaucher’s disease was the first recombinant glycoprotein produced in an engineered carrot plant root cell line that hit the market in 2012. Alpha galactosidase-A, human tumor necrosis factor receptor II, glucocerebrosidase, interferon alpha, even a humanized and glyco-optimized anti-CD20 antibody have also been acquired through plant expression system.
Fig.3 Major systems used in glycoprotein production (Swiech, 2015).
Creative Biolabs is committed to providing optional expression systems for glycoprotein production and high-quality glycoprotein products to promote the progress of your projects. Please contact us for more information and a detailed quote.