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- Eisenhut, P., et al.
(författare)
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Systematic use of synthetic 5'-UTR RNA structures to tune protein translation improves yield and quality of complex proteins in mammalian cell factories
- 2020
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Ingår i: Nucleic Acids Research. - : Oxford University Press (OUP). - 0305-1048 .- 1362-4962. ; 48:20
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Tidskriftsartikel (refereegranskat)abstract
- Predictably regulating protein expression levels to improve recombinant protein production has become an important tool, but is still rarely applied to engineer mammalian cells. We therefore sought to set-up an easy-to-implement toolbox to facilitate fast and reliable regulation of protein expression in mammalian cells by introducing defined RNA hairpins, termed 'regulation elements (RgE)', in the 5'-untranslated region (UTR) to impact translation efficiency. RgEs varying in thermodynamic stability, GC-content and position were added to the 5'-UTR of a fluorescent reporter gene. Predictable translation dosage over two orders of magnitude in mammalian cell lines of hamster and human origin was confirmed by flow cytometry. Tuning heavy chain expression of an IgG with the RgEs to various levels eventually resulted in up to 3.5-fold increased titers and fewer IgG aggregates and fragments in CHO cells. Co-expression of a therapeutic Arylsulfatase-A with RgE-tuned levels of the required helper factor SUMF1 demonstrated that the maximum specific sulfatase activity was already attained at lower SUMF1 expression levels, while specific production rates steadily decreased with increasing helper expression. In summary, we show that defined 5'-UTR RNA-structures represent a valid tool to systematically tune protein expression levels in mammalian cells and eventually help to optimize recombinant protein expression.
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| 2. |
- Malm, Magdalena, 1983-, et al.
(författare)
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Harnessing secretory pathway differences between HEK293 and CHO to rescue production of difficult to express proteins
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Annan publikation (övrigt vetenskapligt/konstnärligt)abstract
- Biologics represent the fastest growing group of therapeutics, but many advanced recombinant protein moieties remain difficult to produce. Here, we identify bottlenecks limiting expression of recombinant human proteins through a systems biology analysis of the transcriptomes of CHO and HEK293 during recombinant overexpression. Surprisingly, one third of the challenging human proteins displayed improved secretion upon host cell swapping from CHO to HEK293. While most components of the secretory machinery showed comparable expression levels in both expression hosts, genes with significant expression variation were identified. Among these, ATF4, SRP9, JUN, PDIA3 and HSPA8 were validated as productivity boosters in CHO. Further, more heavily glycosylated products benefitted more from the elevated activities of the N- and O-glycosyltransferases found in HEK293. Collectively, our results demonstrate the utilization of HEK293 for expression rescue of human proteins and suggest a methodology for identification of secretory pathway components improving recombinant protein yield in HEK293 and CHO.
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| 3. |
- Moradi Barzadd, Mona, 1987-
(författare)
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Strategies to improve and balance the expression levels of recombinant proteins in mammalian cell lines
- 2021
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Proteins are the building blocks of all living organisms enabling us to function and survive. There are more than 100,000 different proteins in the human body performing a variety of vital tasks. Examples of essential proteins are antibodies defending our body against foreign invaders and hemoglobulin responsible for importing oxygen to our cells and exporting carbon dioxide out from our cells. Consequently, mutations leading to dysfunctional proteins is the cause of many known diseases. Fortunately, the advancement of modern medicine has enabled proteins also to be employed as therapeutics to treat and cure various conditions. For instance, human insulin is recombinantly produced in the bacterium E. coli and is used as a biopharmaceutical to treat patients with Diabetes. The increased knowledge about diseases, their cause, and what cellular pathway to target has led to the discovery of many novel and complex biologics. Hence, the manufacturing of biopharmaceuticals is a rapidly emerging field that enables the production of complex molecules that are target-specific, effective, and highly active in the human body. Mammalian cell lines are often the preferred cell factories for manufacturing biologics since they generate proteins with human-like post-translational modifications, which are often essential features to obtain functional, safe, and effective therapeutics. Unfortunately, these life-saving biologics are costly, making them affordable for a fraction of patients worldwide. Therefore, one of the goals of the biotech industry is to make accessible biologics for everyone who needs it regardless of financial background. One way to achieve this goal is to engineer mammalian cell factories to improve the quantity and quality of biopharmaceuticals while reducing the production cost.The results presented in this thesis are the outcome of five different studies aiming to improve and balance the expression levels of recombinant proteins in mammalian cell lines. In the first study, we investigated the productivity differences between mammalian cell lines from different origins. In the second and third projects, by utilizing transcriptomic analysis, helper genes were identified for improving the quantity and quality of two difficult-to-express biologics. The fourth study generated an easy-to-use toolbox for balancing the expression levels of recombinant proteins in mammalian cell lines. In the final project, the toolbox from the fourth project was employed to develop an in vitro cell-based cancer assay which is a crucial tool in cancer research and drug discovery.In summary, this thesis provides strategies to improve the production process of biologics in mammalian cell lines and thereby contributes to the goal of offering safe, effective, and affordable medicine to patients in every part of this world.
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