Targeted genetic modification of cell lines for recombinant protein production.
Ontology highlight
ABSTRACT:
SUBMITTER: Barron N
PROVIDER: S-EPMC2267619 | biostudies-other | 2007 Apr
REPOSITORIES: biostudies-other
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Project description:Direct oral anticoagulants (DOAC) are substrates for the ABCB1 transporter (also called P-glycoprotein), an active efflux pump. ABCB1 polymorphisms have been previously reported to influence the pharmacokinetics of several drugs such as immunosuppressants and tyrosine kinase inhibitors. Recently, in vivo studies have suggested that genetic variants might contribute to the inter-individual variability in DOAC plasma concentrations. Therefore, we evaluated the in vitro effect of the most common coding ABCB1 single nucleotide polymorphisms (SNP), 1236?C?>?T-2677G?>?T-3435C?>?T, and the coding ABCB1 1199?G?>?A SNP on the transport activity towards rivaroxaban. HEK293 cells were transfected to overexpress the ABCB1 wild-type (1236C-2677G-3435C, 1199?G) or variant proteins (1236C-2677G-3435T, 1236T-2677T-3435T or 1199?A). ABCB1 expression decreased the intracellular accumulation of rivaroxaban, when compared to control cells. This confirms the involvement of ABCB1 in the active transport of rivaroxaban. However, the ABCB1 1236?C?>?T-2677G?>?T-3435C?>?T and 1199?G?>?A SNPs had no significant influence on the intracellular accumulation of rivaroxaban when compared to the wild-type protein. These results suggest that the ABCB1 coding SNPs investigated in the present study are unlikely to contribute to the inter-individual variability in rivaroxaban plasma concentrations.
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Project description:BackgroundThe methylotrophic yeast Pichia pastoris is an appealing production host for a variety of recombinant proteins, including biologics. In this sense, various genetic- and non-genetic-based techniques have been implemented to improve the production efficiency of this expression platform. Loss of supression (Los1) encodes a non-essential nuclear tRNA exporter in Saccharomyces cerevisiae, which its deletion extends replicative lifespan. Herein, a los1-deficient strain of P. pastoris was generated and characterized.MethodsA gene disruption cassette was prepared and transformed into an anti-CD22-expressing strain of P. pastoris. A δ los1 mutant was isolated and confirmed. The drug sensitivity of the mutant was also assessed. The growth pattern and the level of anti-CD22 single-chain variable fragment (scFv) expression were compared between the parent and mutant strains.ResuultsThe los1 homologue was found to be a non-essential gene in P. pastoris. Furthermore, the susceptibility of los1 deletion strain to protein synthesis inhibitors was altered. This strain showed an approximately 1.85-fold increase in the extracellular level of anti-CD22 scFv (p < 0.05). The maximum concentrations of total proteins secreted by δ los1 and parent strains were 125 mg/L and 68 mg/L, respectively.ConclusionThe presented data suggest that the targeted disruption of los1 homologue in P. pastoris can result in a higher expression level of our target protein. Findings of this study may improve the current strategies used in optimizing the productivity of recombinant P. pastoris strains.
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Project description:Genetically encoded unnatural amino acids provide powerful strategies for modulating the molecular functions of proteins in mammalian cells. However this approach has not been coupled to genome-wide measurements, because efficient unnatural amino acid incorporation is limited to readily transfectable cells and leads to very heterogeneous expression. We demonstrate that rapid piggybac integration of the orthogonal pyrrolysyl-tRNA synthetase (PylS)/tRNAPyl CUA pair (and its derivatives) into the mammalian genome enables efficient, homogeneous unnatural amino acid incorporation into target proteins in diverse cells, and we reveal the distinct transcriptional responses of ES cells and MEFs to amber suppression. Genetically encoding Nε-acetyl-lysine in place of six lysine residues in histone H3, that are known to be post-translationally acetylated, enables deposition of pre-acetylated histones into cellular chromatin, via a synthetic pathway that is orthogonal to enzymatic modification, allowing us to determine the consequences of acetylation at specific amino acids in histones on gene expression. mRNA was sequenced using polyA-enrichment and Truseq library preparation protocol. Two biological replicates were sequences for each cell line and condition
2016-07-03 | E-GEOD-73823 | biostudies-arrayexpress
Project description:The intracellular penetration of darunavir, a second-generation HIV protease inhibitor, is limited by the activity of the efflux P-glycoprotein (ABCB1). ABCB1 expression and/or activity levels can vary between individuals due to genetic polymorphisms including the c.1199G>A, c.1236C>T, c.2677G>T and c.3435C>T variants, which could in part explain why the pharmacokinetics of darunavir are so variable from one individual to another. While a few clinical studies have failed to demonstrate an influence of these polymorphisms on darunavir pharmacokinetics, drug-drug interactions and methodological limitations may have prevented them from revealing the true influence of ABCB1 variants. In this work, we report on the intracellular accumulation of darunavir in recombinant HEK293 cell lines expressing wild-type ABCB1 or one of several variants: ABCB1 1199A, ABCB1 3435T, and ABCB1 1236T/2677T/3435T. We demonstrate that while ABCB1 expression limits intracellular accumulation of darunavir, there is no significant difference in efflux activity between cells expressing wild-type ABCB1 and those that express any of the studied variants.
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