title: CHO Cells adapted to inorganic phosphate limitation show higher growth and higher pyruvate carboxylase flux in phosphate replete conditions.
abstract: Inorganic phosphate (Pi) is an essential ion involved in diverse cellular processes including metabolism. Changes in cellular metabolism upon long term adaptation to Pilimitation have been reported in E. coli. Given the essential role of Pi, adaptation to Pilimitation may also result in metabolic changes in animal cells. In this study, we have adapted CHO cells producing recombinant IgG to limiting Piconditions for 75 days. Not surprisingly, adapted cells showed better survival under Pilimitation. Here, we report the finding that such cells also showed better growth characteristics compared to control in batch culture replete with Pi(higher peak density and integral viable cell density), accompanied by a lower specific oxygen uptake rate and cytochrome oxidase activity towards the end of exponential phase. Surprisingly, the adapted cells grew to a lower peak density under glucose limitation. This suggests long term Pilimitation may lead to selection for an altered metabolism with higher dependence on glucose availability for biomass assimilation compared to control. Steady state U-13C glucose labeling experiments suggest that adapted cells have a higher pyruvate carboxylase flux. Consistent with this observation, supplementation with aspartate abolished the peak density difference whereas supplementation with serine did not abolish the difference. This supports the hypothesis that cell growth in the adapted culture might be higher due to a higher pyruvate carboxylase flux. Decreased fitness under carbon limitation and mutations in the sucABCD operon has been previously reported in E. coli upon long term adaptation to Pilimitation, suggestive of a similarity in cellular response among such diverse species. © 2017 American Institute of Chemical Engineers Biotechnol. Prog., 33:749-758, 2017.
authors.affiliation: Chemical Engineering and Process Development Div., CSIR-National Chemical Laboratory, Pune, 411008, India.|CSIR-National Chemical Laboratory Campus, Academy of Scientific and Innovative Research, Pune.
authors.forename: Vishwanathgouda
authors.initials: V
authors.lastname: Maralingannavar
authors.affiliation: Chemical Engineering and Process Development Div., CSIR-National Chemical Laboratory, Pune, 411008, India.|CSIR-National Chemical Laboratory Campus, Academy of Scientific and Innovative Research, Pune.
authors.forename: Dharmeshkumar
authors.initials: D
authors.lastname: Parmar
authors.affiliation: Chemical Engineering and Process Development Div., CSIR-National Chemical Laboratory, Pune, 411008, India.
authors.forename: Tejal
authors.initials: T
authors.lastname: Pant
authors.affiliation: Chemical Engineering and Process Development Div., CSIR-National Chemical Laboratory, Pune, 411008, India.|CSIR-National Chemical Laboratory Campus, Academy of Scientific and Innovative Research, Pune.
authors.forename: Chetan
authors.initials: C
authors.lastname: Gadgil
authors.affiliation: Chemical Engineering and Process Development Div., CSIR-National Chemical Laboratory, Pune, 411008, India.|CSIR-National Chemical Laboratory Campus, Academy of Scientific and Innovative Research, Pune.
authors.forename: Venkateswarlu
authors.initials: V
authors.lastname: Panchagnula
authors.affiliation: Chemical Engineering and Process Development Div., CSIR-National Chemical Laboratory, Pune, 411008, India.|CSIR-National Chemical Laboratory Campus, Academy of Scientific and Innovative Research, Pune.
authors.forename: Mugdha
authors.identifier: http://orcid.org/0000-0003-1703-789X
authors.initials: M
authors.lastname: Gadgil
mesh_terms: D000818:Animals; D016466:CHO Cells; D003412:Cricetulus; D003576:Electron Transport Complex IV / Q000378:metabolism; D010100:Oxygen / Q000378:metabolism; D010710:Phosphates / Q000172:deficiency / Q000378:metabolism*; D011766:Pyruvate Carboxylase / Q000378:metabolism*
chemical_list: D010710:Phosphates; D003576:Electron Transport Complex IV; D011766:Pyruvate Carboxylase; D010100:Oxygen
keywords: inorganic phosphate limitation; nutrient limited adaptation; oxygen uptake