Increase in K+ and alpha-AIB active transport in CHO cells after low [K+] treatment

1982 ◽  
Vol 243 (3) ◽  
pp. C124-C132 ◽  
Author(s):  
J. S. Graves ◽  
D. D. Wheeler
Keyword(s):  
Amino Acid ◽  
Chinese Hamster Ovary ◽  
Cho Cells ◽  
Chinese Hamster ◽  
Transport Systems ◽  
Acid Transport ◽  
Transport Capacity ◽  
Prolonged Incubation ◽  
Apparent Increase ◽  
Low K

We have studied the effects of prolonged incubation in low [K+] medium (approximately 0.3 mM) on both K+ and amino acid transport in Chinese hamster ovary (CHO) cells. When incubated in low [K+] medium, CHO cells redressed partially the loss of intracellular K+ after 12 h. After 24 h of incubation, both the activity of Na+-K+-ATPase in crude homogenates, and the transport capacity (Vmax) for ouabain-sensitive (i.e., active) K+ influx approximately doubled. The magnitude of the ouabain-insensitive (i.e., passive) K+ influx decreased by 50%. Thus the regulatory response involves an apparent increase in Na+-K+ pump and a decrease in K+ leak. The transport capacity for the nonmetabolized amino acid, alpha-aminoisobutyric acid (alpha-AIB), also increased after 24 h in low [K+] medium. The Vmax for the Na+-dependent (i.e., active) alpha-AIB influx increased by about 150%, and the magnitude of the Na+-independent influx increased by 20-40%. These changes in alpha-AIB transport result in a twofold greater capacity to accumulate this amino acid. Thus the regulation of K+ and alpha-AIB transport systems appears to be linked and possible mechanisms of this linkage are discussed.

Membrane potential and amino acid transport in a mutant chinese hamster ovary cell line

1991 ◽  
Vol 146 (3) ◽  
pp. 417-424 ◽  
Author(s):  
Bianca Maria Rotoli ◽  
Ovidio Bussolati ◽  
Valeria Dall'asta ◽  
Gian Carlo Gazzola
Keyword(s):  
Membrane Potential ◽  
Amino Acid ◽  
Cell Line ◽  
Chinese Hamster Ovary Cell ◽  
Chinese Hamster Ovary ◽  
Amino Acid Transport ◽  
Chinese Hamster ◽  
Ovary Cell ◽  
Acid Transport ◽  
Ovary Cell Line

scholarly journals Expression of the surface antigen 4F2hc affects system-L-like neutral-amino-acid-transport activity in mammalian cells

1997 ◽  
Vol 324 (2) ◽  
pp. 535-541 ◽  
Author(s):  
Stefan BRÖER ◽  
Angelika BRÖER ◽  
Bernd HAMPRECHT
Keyword(s):  
Amino Acid ◽  
Surface Antigen ◽  
Amino Acid Transport ◽  
Cho Cells ◽  
Mammalian Cells ◽  
Primary Cultures ◽  
Transport Systems ◽  
Acid Transport ◽  
Transport Activity ◽  
System L

Mammalian cells possess a variety of amino acid-transport systems with overlapping substrate specificity. System L is one of the major amino acid-transport systems of non-epithelial cells. By expression cloning we have recently demonstrated that the surface antigen 4F2hc (CD98) is a necessary component for expression of system-L-like amino acid-transport activity in C6-BU-1 rat glioma cells [Bröer, Bröer and Hamprecht (1995) Biochem. J. 312, 863–870]. 4F2hc mRNA was detected in CHO cells, COS cells, activated lymphocytes isolated from mouse spleen and primary cultures of astrocytes. In all these cell types, Na+-independent isoleucine transport was mediated by system L. No contribution of system y+L to isoleucine or arginine transport was detected in C6-BU-1 cells. In lymphocytes, both system-L-like amino acid-transport activity and 4F2hc mRNA levels increased after treatment with phorbol ester plus ionomycin. Antisense oligonucleotides caused modest inhibition of Na+-independent isoleucine transport in C6-BU-1 cells and primary cultures of astroglial cells, whereas arginine transport was unaffected. Overexpression of 4F2hc cDNA in CHO cells resulted in an increase in Na+-independent isoleucine transport.

scholarly journals Amino Acid Requirements of the Chinese Hamster Ovary Cell Metabolism during Recombinant Protein Production

2019 ◽  
Author(s):  
Bergthor Traustason
Keyword(s):  
Amino Acids ◽  
Amino Acid ◽  
Recombinant Protein ◽  
Recombinant Proteins ◽  
Chinese Hamster Ovary ◽  
Cho Cells ◽  
Chinese Hamster ◽  
Ovary Cell ◽  
Scale Model ◽  
Amino Acid Requirements

SummaryMajority of biopharmaceutical drugs today are produced by Chinese hamster ovary (CHO) cells, which have been the standard industry host for the past decades. To produce and secrete a substantial amount of the target recombinant proteins the CHO cells must be provided with suitable growth conditions and provided with the necessary nutrients. Amino acids play a key role in this as the building blocks of proteins, playing important roles in a large number of metabolic pathways and being important sources of nitrogen as well as carbon under certain conditions. In this study exploratory analysis of the amino acid requirements of CHO cells was carried out using metabolic modelling approaches. Flux balance analysis was employed to evaluate the optimal distribution of fluxes in a genome-scale model of CHO cells to gain information on the cells’ metabolic response in silico.The results showed that providing non-essential amino acids (NEAAs) has a positive effect on CHO cell biomass production and that cysteine as well as tyrosine play a fundamental role in this. This implies that extracellular provision of NEAAs limits the extent of energy loss in amino acid biosynthetic pathways and renders additional reducing power available for other biological processes. Detailed analysis of the possible secretion and uptake of D-serine in the CHO model was also performed and its influence on the rest of the metabolism mapped out, which revealed results matching various existing literature. This is interesting since no mention of D-serine in regard to CHO cells was found in current literature, as well as the fact that this opens up the possibility of using the model for better understanding of certain disorders in higher up organisms that have been implicated with D-serine, such as motor neuron and cognitive degeneration. Finally, outcome from the model optimisation of different recombinant proteins demonstrated clearly how the difference in protein structure and size can influence the production outcome. These results show that systematic and model-based approaches have great potential for broad de novo exploration as well as being able to handle the cellular burden associated with the production of different types of recombinant protein.

scholarly journals Expression of a human gene for polyamine transport in Chinese-hamster ovary cells

1989 ◽  
Vol 263 (3) ◽  
pp. 745-752 ◽  
Author(s):  
T L Byers ◽  
R Wechter ◽  
M E Nuttall ◽  
A E Pegg
Keyword(s):  
Transport System ◽  
Chinese Hamster Ovary ◽  
Cho Cells ◽  
Chinese Hamster Ovary Cells ◽  
Mutant Cell ◽  
Molecular Genetic ◽  
Chinese Hamster ◽  
Transport Systems ◽  
Polyamine Transport System ◽  
Polyamine Transport

A molecular-genetic approach towards isolating mammalian polyamine-transport genes and their encoded proteins was devised involving the production of Chinese-hamster ovary (CHO) cells expressing a human polyamine-transport protein. CHO cells and a polyamine-transport-deficient CHO mutant cell line (CHOMG) were equally sensitive to the antiproliferative effects of alpha-difluoromethylornithine (DFMO), which blocked endogenous polyamine synthesis. Exposure to exogenous polyamines increased intracellular polyamine levels and reversed this DFMO-induced cytostasis in the CHO cells, but not in the CHOMG cells. CHOMG cells were therefore transfected with human DNA (isolated from HT-29 colon carcinoma cells) and cells expressing the human polyamine-transport system were identified by the ability of these cells to grow in a medium containing DFMO and polyamines. A number of different positive clones were identified and shown to have the capacity for polyamine uptake and an increased sensitivity to the toxic effects of the polyamine analogue methylglyoxal bis(guanylhydrazone). Differences in these properties between the clones are consistent with a multiplicity of polyamine-transport systems. Some clones also showed a change in growth characteristics, which may indicate a relationship between genes involved in the polyamine-transport system and in cell proliferation.

scholarly journals Recessive constitutive mutant Chinese hamster ovary cells (CHO-K1) with an altered A system for amino acid transport and the mechanism of gene regulation of the A system.

1984 ◽  
Vol 4 (4) ◽  
pp. 799-808 ◽  
Author(s):  
J Moffett ◽  
E Englesberg
Keyword(s):  
Amino Acids ◽  
Amino Acid ◽  
Chinese Hamster Ovary ◽  
Amino Acid Transport ◽  
Actinomycin D ◽  
Chinese Hamster Ovary Cells ◽  
Chinese Hamster ◽  
Acid Transport ◽  
Ovary Cells ◽  
Proline Transport

Chinese hamster ovary cells (CHO-K1) starved for 24 h for amino acids show a severalfold increase in velocity of proline transport through the A system (Vmax is five times that of unstarved cells). This increase is inhibited by cycloheximide, actinomycin D, N-methyl-alpha-amino isobutyric acid (MeAIB, a non-metabolizable specific A system amino acid analog), and by other amino acids that are generally transported by the A system. However, transport by the A system is not a prerequisite for this repression, and all compounds that have affinity for the A system do not necessarily act as "co-repressors." The addition of proline, MeAIB, or other amino acids, as described above, to derepressed cells results in a rapid decrease in A system activity. As shown with proline and MeAIB, this decrease in activity is in part due to a rapid trans-inhibition and a slow, irreversible inactivation of the A system. Neither process is inhibited by cycloheximide or actinomycin D. Alanine antagonizes the growth of CHO-K1 pro cells by preventing proline transport, and alanine-resistant mutants (alar) have been isolated (Moffett et al., Somatic Cell Genet. 9:189-213, 1983). alar2 and alar4 are partial and full constitutive mutants for the A system and have two and six times the Vmax for proline uptake by the A system, respectively. The A system in alar4 is also immune to the co-repressor-induced inactivation. Both alar2 and alar4 phenotypes are recessive. Alar3 shows an increase in Vmax and Km for proline transport through the A system, and this phenotype is codominant. All three mutants have a pleiotropic effect, producing increases in activity of the ASC and P systems of amino acid transport. This increase is not due to an increase in the Na+ gradient. The ASC and P phenotypes behave similarly to the A system in hybrids. A model has been proposed incorporating these results.

Control of amino acid transport into Chinese hamster ovary cells

2018 ◽  
Vol 115 (12) ◽  
pp. 2908-2929 ◽  
Author(s):  
Darren Geoghegan ◽  
Claire Arnall ◽  
Diane Hatton ◽  
Joanne Noble-Longster ◽  
Christopher Sellick ◽  
...  
Keyword(s):  
Amino Acid ◽  
Chinese Hamster Ovary ◽  
Amino Acid Transport ◽  
Chinese Hamster Ovary Cells ◽  
Chinese Hamster ◽  
Acid Transport ◽  
Ovary Cells
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