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Bergen, Norway

Bort J.A.H.,University of Natural Resources and Life Sciences, Vienna | Stern B.,UniTargetingResearch AS | Borth N.,University of Natural Resources and Life Sciences, Vienna
Biotechnology Journal

During the process of recombinant cell line optimisation for production of biopharmaceuticals, multiple cellular properties like robustness against stress, the attainment of high cell concentrations and maintenance of high viability must be considered to maximize protein yield. To improve growth and viability, glutamine is supplemented as an alternative energy source for rapidly dividing cells that oxidize glucose inefficiently. However, the resulting by-product ammonia is toxic at high concentrations and has a negative impact on protein glycosylation, a major quality-determining parameter of biopharmaceuticals. In this work, the CHO-K1 cell line was adapted to a chemically defined medium and suspension growth within 3 weeks. Subsequently, the glutamine concentration was stepwise reduced from 8 to 4 and 2 mM. After each reduction, both the final cell concentration in the batch and the viability decreased. To force a rapid evolution of cells to achieve high final cell concentrations, cells were seeded at high densities (107 cells/mL) and surviving cells were sorted by FACS or MACS when viability declined to 10% (typically after 24 h). Sorted cells were grown in batch until viability declined to 10% and viable cells recovered again. The final sorted population was able to reach comparable or even better viable cell concentrations and showed a significantly improved viability compared to their ancestors. The 2 mM glutamine-adapted cell line was directly transferred into glutamine-free medium and was able to grow at comparable rates without requiring further adaptation. Cells compensated the lack of glutamine by increasing their consumption of glutamate and aspartate. © 2010 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim. Source

UniTargetingResearch AS | Date: 2010-08-12

The invention relates to a method to generate rational libraries comprising genetic elements which are involved in transcriptional and/or translational regulation of a gene and devised to increase the production yield of the encoded protein as well as to the rational library and to the application of said rational library.

Khaziapoul S.,Northumbria University | Pearson M.J.,Northumbria University | Pryme I.F.,UniTargetingResearch AS | Pryme I.F.,University of Bergen | And 3 more authors.
Biochemical and Biophysical Research Communications

3' Untranslated regions (3'UTRs) of messenger RNAs have important roles in post-transcriptional regulation of gene expression and this is partly achieved through binding of specific proteins to sequences or structures within these regions. Previously, replacement of a native luciferase 3'UTR with the human albumin 3'UTR has been found to lead to a 10-fold increase in luciferase reporter activity. In this work we investigated protein binding to the human albumin 3'UTR. Electrophoretic mobility shift and UV cross-linking assays indicate that a ∼50. kDa protein from Chinese Hamster Ovary (CHO) cells binds to the albumin 3'UTR, and affinity experiments followed by proteomics identified this protein as CUG binding protein 1 (CUG-BP1, also known as CELF1). Deletion analysis of the albumin 3'UTR showed that nucleotides 1-50 and nucleotides 101-150 are not required for binding but that removal of nucleotides 51-100 caused a loss in binding. The results suggest that CUG-BP1 binds to nucleotides 51-100 of the human albumin 3'UTR. In human cells CUG-BP1 binding may thus play a role in regulation of albumin expression and, additionally, it may have a function in post-transcriptional control in CHO cells. © 2012 Elsevier Inc. Source

Pearson M.J.,Northumbria University | Khazaipoul S.,Northumbria University | Optun A.,UniTargetingResearch AS | Pryme I.F.,UniTargetingResearch AS | And 4 more authors.
Biotechnology Journal

Chinese hamster ovary (CHO) cells are used for recombinant protein production in the pharmaceutical industry but there is a need to improve expression levels. In the present work experiments were carried out to test the effectiveness of different 3′untranslated regions (3′UTRs) in promoting production of a naturally secreted luciferase. Seamless cloning was used to produce expression vectors in which Gaussia princeps luciferase coding sequences were linked to the human albumin, immunoglobulin or chymotrypsinogen 3′UTR. Stably transfected CHO cells expressing these constructs were selected. Luciferase activity in the culture medium was increased 2-3-fold by replacing the endogenous 3′UTR with the albumin 3′UTR and decreased by replacement with immunoglobulin or chymotrypsinogen 3′UTR. Replacement of the native 3′UTR with the albumin 3′UTR led to a 10-fold increase in luciferase mRNA levels. Deletion analysis of the albumin 3′UTR showed that loss of nucleotides 1-50, which removed an AU-rich complex stem loop region, caused significant reductions in both luciferase protein expression and luciferase mRNA levels. The results suggest that recombinant protein expression and yield could be improved by the careful selection of appropriate 3′UTR sequences. © 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim. Source

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