Unknown,Transcriptomics,Genomics,Proteomics

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Pilot project to determine optimal bioreactor protein glycosylation conditions

ABSTRACT: These research areas concentrate on stress induced proteases in recombinant Escherichia coli, glycosylation heterogeneity due to bioprocess conditions produced in mammalian cells, and metabolic engineering of E. coli. The hypothesis of this project is that recombinant protein glycosylation is inefficient under normal bioreactor conditions since the additional glycosylation reactions necessary for the recombinant protein exceed the metabolic capacity of the cells. Normal bioreactor conditions have been optimized for cell growth, and sometimes for protein productivity. Only recently has it been accepted that optimal glycosylation may not occur under optimal growth or protein productivity conditions. Specific Aim: Determine the relationship between bioreactor conditions and glycosylation gene expression in NS0 cells. EXPERIMENT: Mouse NS0 myeloma cells were grown in culture, stressed with 5 mM NaCl, 10 mM proline plus 5 mM ammonia, or 5 mM ammonia, along with an unstressed control group. The growth of the cultures were followed until the late exponential phase (90 hours), at which time two 50 mLs of cells were harvested and RNA extracted. Samples were prepared in triplicate, for a total of 12 samples. The RNA was amplified and labeled by Microarray Core (E) and hybridized to the GLYCOv3 microarrays.

ORGANISM(S): Mus musculus

SUBMITTER: Steven Head

PROVIDER: E-GEOD-28920 | biostudies-arrayexpress |

REPOSITORIES: biostudies-arrayexpress

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Project description:Irani2015 - Genome-scale metabolic model of P.pastoris N-glycosylation This model is described in the article: Genome-scale metabolic model of Pichia pastoris with native and humanized glycosylation of recombinant proteins. Irani ZA, Kerkhoven E, Shojaosadati SA, Nielsen J. Biotechnol. Bioeng. 2015 Oct; Abstract: Pichia pastoris is used for commercial production of human therapeutic proteins, and genome-scale models of P. pastoris metabolism have been generated in the past to study the metabolism and associated protein production by this yeast. A major challenge with clinical usage of recombinant proteins produced by P. pastoris is the difference in N-glycosylation of proteins produced by humans and this yeast. However, through metabolic engineering a P. pastoris strain capable of producing humanized N-glycosylated proteins was constructed. The current genome-scale models of P. pastoris do not address native nor humanized N-glycosylation, and we therefore developed ihGlycopastoris, an extension to the iLC915 model with both native and humanized N-glycosylation for recombinant protein production, but also an estimation of N-glycosylation of P. pastoris native proteins. This new model gives a better predictions of protein yield, demonstrates the effect of the different types of N-glycosylation of protein yield, and can be used to predict potential targets for strain improvement. The model represents a step towards a more complete description of protein production in P. pastoris, which is required for using these models to understand and optimize protein production processes. This article is protected by copyright. All rights reserved. This model is hosted on BioModels Database and identified by: MODEL1510220000. To cite BioModels Database, please use: BioModels Database: An enhanced, curated and annotated resource for published quantitative kinetic models. To the extent possible under law, all copyright and related or neighbouring rights to this encoded model have been dedicated to the public domain worldwide. Please refer to CC0 Public Domain Dedication for more information.

Project description:The transcriptome profiles for wild-type (plasmid-free) and recombinant (plasmid-bearing) Escherichia coli during well-controlled synchronized high-cell-density fed-batch cultures were analyzed by DNA microarrays. It was observed that the growth phase significantly affected the transcriptome profiles, and the transcriptome profiles were significantly different for the recombinant and wild-type cultures. The response of the wild-type and recombinant cultures to an isopropyl-1-thio-β-D-galactopyranoside- (IPTG-) addition was examined, where IPTG induced recombinant protein production in the plasmid-bearing cultures. The IPTG-addition significantly altered the transcriptome response of the wild-type cultures entering the stationary phase. The IPTG-induced recombinant protein production resulted in a significant down-regulation of many energy synthesis genes (atp, nuo, cyo), as well as nearly all transcription- and translation-related genes (rpo, rpl, rpm, rps, rrf, rrl, rrs). Numerous phage (psp, hfl) and transposon-related genes (tra, ins) were significantly regulated in the recombinant cultures due to the IPTG-induction. These results indicate that the signaling mechanism, associated with the recombinant protein production, may induce a metabolic burden in the form of a phage defense mechanism. Taken together, these results indicated that recombinant protein production initiated a cascade of transcriptome responses that down-regulated the very genes needed to sustain productivity. In this study, the transcriptome profiles for recombinant and wild-type E. coli cultures were compared. The recombinant and wild-type cultures were monitored during the exponential growth phase and as the cultures entered the stationary phase. Well-controlled fed-batch fermenters were used to synchronize the high-cell density cultures. E. coli MG1655 [pPROEx-CAT] and E. coli MG1655 (plasmid-free) were exposed to IPTG in the exponential phase, where chloramphenicol acetyltransferase (CAT) expression was induced in the plasmid-bearing cultures. Control cultures, not exposed to IPTG, were also examined. The gene expression profiles were determined using DNA microarrays. Recombinant protein production was shown to result in a metabolic burden due to significant down-regulation of the transcription, translation, and energy synthesis genes. This was the first comprehensive study that has examined the transcriptome of wild-type and recombinant cultures under the same set of conditions. This data indicated that one cannot merely extrapolate the behavior of recombinant cultures from wild-type culture data. Experiment Overall Design: All fermentations were synchronized in time to the time at which the cell density reached approximately 11.5 OD, or roughly 70% of the fermenter’s maximum cell density. IPTG (5 mM) was added when the cell density reached the targeted OD for the cultures to be induced. Cells were harvested at 0, 1, 2, 3, 4, and 5 hours relative to the synchronization time point (identified as Time S0, S1, etc). Each fermentation condition was conducted in duplicate. For the recombinant Control Time S0 sample, triplicate samples were available since prior to the IPTG-addition, all fermentations within a strain were replicates. All fermentation conditions were repeated twice (two biological replicates). RNA from each biological replicate was purified and processed independently. Three biological replicates were obtained from for the recombinant Control sample (Time S0) since the cultures prior to the IPTG-addition were replicates. Prior to hybridization, where only two biological replicates existed, one of the RNA samples was divided into two technical replicates, resulting in three separate hybridized chips. The wild-type Time S0 samples and all Time S1 and S4 samples contained data from three DNA microarrays obtained from two biological duplicates (30 DNA microarrays total).

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Pilot project to determine optimal bioreactor protein glycosylation conditions

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