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Background
Japanese encephalitis virus (JEV) NS5 is a viral nonstructural protein that carries both methyltransferase and RNA-dependent RNA polymerase (RdRp) domains. It is a key component of the viral RNA replicase complex that presumably includes other viral nonstructural and cellular proteins. The biochemical properties of JEV NS5 have not been characterized due to the lack of a robust in vitro RdRp assay system, and the molecular mechanisms for the initiation of RNA synthesis by JEV NS5 remain to be elucidated. 相似文献3.
The use of glycine betaine combined with hyperosmolality is known to be an efficient means for achieving high protein production in recombinant Chinese hamster ovary (rCHO) cells. In order to understand the intracellular events and identify the key factors in rCHO cells cultivated with glycine betaine under hyperosmotic conditions, two-dimensional differential in-gel electrophoresis (2D-DIGE) followed by mass spectrometric analysis was applied. Differentially expressed 19 protein spots were selected and 16 different kinds of proteins were successfully identified. The identified proteins were associated with cellular metabolism (PEPCK, GAPDH, and PK), cellular architecture (β-tubulin and β-actin), protein folding (GRP78 and OSP94), mRNA processing (Rbm34, ACF, and IPMK), and protein secretion (γ-COP). 2D-Western blot analysis of β-tubulin, GAPDH, Peroxidoxin-1, and GRP78 confirmed the proteomic findings. The proteins identified from this study, which are related to cell growth and antibody production, can be applied to cell engineering for maximizing the efficacy of the use of glycine betaine combined with hyperosmolality in rCHO cells. 相似文献
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Kim JY Kim YG Han YK Choi HS Kim YH Lee GM 《Applied microbiology and biotechnology》2011,89(6):1917-1928
In order to understand the intracellular responses in recombinant CHO (rCHO) cells producing antibody in serum-free medium
(SFM) supplemented with optimized hydrolysates mixtures, yielding the highest specific growth rate (μ, SFM#S1) or the highest
specific antibody productivity (q
Ab, SFM#S2), differentially expressed proteins in rCHO cells are measured by two-dimensional gel electrophoresis combined with
nano-LC-ESI-Q-TOF tandem MS. The comparative proteomic analysis with basal SFM without hydrolysates revealed that the addition
of hydrolysate mixtures significantly altered the profiles of CHO proteome. In SFM#S1, the expression of metabolism-related
proteins, cytoskeleton-associated proteins, and proliferation-related proteins was up-regulated. On the other hand, the expression
of anti-proliferative proteins and pro-apoptotic protein was down-regulated. In SFM#S2, the expression of various chaperone
proteins and proliferation-linked proteins was altered. 2D-Western blot analysis of differentially expressed proteins confirmed
the proteomic results. Taken together, identification of differentially expressed proteins in CHO cells by a proteomic approach
can provide insights into understanding the effect of hydrolysates on intracellular events and clues to find candidate genes
for cell engineering to maximize the protein production in rCHO cells. 相似文献
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Lee Joo-Hyoung Park Jong-Ho Park Sun-Hye Kim Sun-Hong Kim Jee Yon Min Jeong-Ki Lee Gyun Min Kim Yeon-Gu 《Applied microbiology and biotechnology》2018,102(11):4729-4739
Applied Microbiology and Biotechnology - Despite the relatively low transfection efficiency and low specific foreign protein productivity (qp) of Chinese hamster ovary (CHO) cell-based transient... 相似文献
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The hepatitis C virus (HCV) NS5B protein is the viral RNA-dependent RNA polymerase required for replication of the HCV RNA genome. We have identified a peptide that most closely resembles a short region of the protein kinase C-related kinase 2 (PRK2) by screening of a random 12-mer peptide library displayed on the surface of the M13 bacteriophage with NS5B proteins immobilized on microwell plates. Competitive phage enzyme-linked immunosorbent assay with a synthetic peptide showed that the phage clone displaying this peptide could bind HCV RNA polymerase with a high affinity. Coimmunoprecipitation and colocalization studies demonstrated in vivo interaction of NS5B with PRK2. In vitro kinase assays demonstrated that PRK2 specifically phosphorylates NS5B by interaction with the N-terminal finger domain of NS5B (amino acids 1-187). Consistent with the in vitro NS5B-phosphorylating activity of PRK2, we detected the phosphorylated form of NS5B by metabolic cell labeling. Furthermore, HCV NS5B immunoprecipitated from HCV subgenomic replicon cells was specifically recognized by an antiphosphoserine antibody. Knock-down of the endogenous PRK2 expression using a PRK2-specific small interfering RNA inhibited HCV RNA replication. In contrast, PRK2 overexpression, which was accompanied by an increase of in the level of its active form, dramatically enhanced HCV RNA replication. Altogether, our results indicate that HCV RNA replication is regulated by NS5B phosphorylation by PRK2. 相似文献
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Junhyoung Ahn Jina Park Yeon-Gu Kim Eun Gyo Lee Min-Gon Kim Yong-Beom Shin 《Biotechnology and Bioprocess Engineering》2014,19(2):257-261
The commonly used trypan blue dye exclusion method and other modified cell viability methods, such as fluorescein dye and tetrazolium dye exclusion, artificially introduce toxic chemicals to cells and, thus, alter cellular organelles when measuring cell viability. Therefore, cell viability could be affected by the processes currently used to observe viability. In this study, the cell viability of Chinese hamster ovary (CHO) cells was measured by simply counting attached cells after the cultured CHO cells were attached on a Concanavalin A (Con A) substrate. The efficiency of cell attachment to Con A surfaces was different for live and dead cells allowing the cell viability of CHO cells to be measured without any chemical modifications to the cells. 相似文献
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Hyperosmolality in recombinant Chinese hamster ovary (rCHO) cell cultures induces autophagy and apoptosis. To investigate the effect of Bcl-xL overexpression on autophagy and apoptosis in hyperosmotic rCHO cell cultures, an erythropoietin (EPO)-producing rCHO cell line with regulated Bcl-xL overexpression was subjected to hyperosmolality resulting from NaCl addition in a batch culture and nutrient supplementation in a fed-batch culture. In the batch culture, Bcl-xL overexpression suppressed apoptosis, as evidenced by a decreased amount of cleaved caspase-7 and PARP. Concurrently, Bcl-xL overexpression also delayed autophagy, as indicated by reduced LC3 conversion, from LC3-I to LC3-II. As a result, the cell viability and EPO production were improved by Bcl-xL overexpression. In the fed-batch culture, the simultaneous application of Bcl-xL overexpression and nutrient feeding increased the culture longevity and maximum EPO concentration. Taken together, Bcl-xL overexpression delayed autophagy and apoptosis in hyperosmotic rCHO cell cultures, resulting in increased EPO production. 相似文献
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Constitutively active Ras (CA-Ras) is known to enhance cell growth through the induction of various signaling cascades including the phosphoinositide 3-kinase (PI3K)/Akt and mitogen-activated protein kinase (MAPK)/ERK signaling pathways, although the cellular response is highly dependent on the cell type. To evaluate the effect of CA-Ras overexpression on cell growth in recombinant Chinese hamster ovary (rCHO) cells, an erythropoietin (EPO)-producing rCHO cell line with regulated CA-Ras overexpression (EPO-off-CA-Ras) was established using the Tet-off system. The CA-Ras expression level in EPO-off-CA-Ras cells was tightly regulated by doxycycline addition. Although CA-Ras overexpression slightly increased the viable cell concentration during the late exponential phase, it did not increase the maximum viable cell concentration or specific growth rate to a significant degree. Unexpectedly, CA-Ras overexpression in rCHO cells led only to the enhancement in the activation of the MAPK/ERK signaling pathway and not the PI3K/Akt signaling pathway. Taken together, CA-Ras overexpression in rCHO cells did not significantly affect cell growth; it also had no critical impact on viable cell concentration or EPO production, possibly due to a failure to activate the PI3K/Akt signaling pathway. 相似文献