title: The relationship between mTOR signalling pathway and recombinant antibody productivity in CHO cell lines.
abstract: BACKGROUND
  High recombinant protein productivity in mammalian cell lines is often associated with phenotypic changes in protein content, energy metabolism, and cell growth, but the key determinants that regulate productivity are still not clearly understood. The mammalian target of rapamycin (mTOR) signalling pathway has emerged as a central regulator for many cellular processes including cell growth, apoptosis, metabolism, and protein synthesis. This role of this pathway changes in response to diverse environmental cues and allows the upstream proteins that respond directly to extracellular signals (such as nutrient availability, energy status, and physical stresses) to communicate with downstream effectors which, in turn, regulate various essential cellular processes.
  
  
  RESULTS
  In this study, we have performed a transcriptomic analysis using a pathway-focused polymerase chain reaction (PCR) array to compare the expression of 84 target genes related to the mTOR signalling in two recombinant CHO cell lines with a 17.4-fold difference in specific monoclonal antibody productivity (qp). Eight differentially expressed genes that exhibited more than a 1.5-fold change were identified. Pik3cd (encoding the Class 1A catalytic subunit of phosphatidylinositol 3-kinase [PI3K]) was the most differentially expressed gene having a 71.3-fold higher level of expression in the high producer cell line than in the low producer. The difference in the gene's transcription levels was confirmed at the protein level by examining expression of p110δ.
  
  
  CONCLUSIONS
  Expression of p110δ correlated with specific productivity (qp) across six different CHO cell lines, with a range of expression levels from 3 to 51 pg/cell/day, suggesting that p110δ may be a key factor in regulating productivity in recombinant cell lines.
authors.forename: Raihana
authors.initials: R
authors.lastname: Edros
authors.forename: Susan
authors.initials: S
authors.lastname: McDonnell
authors.affiliation: School of Chemical and Bioprocess Engineering and Conway Institute of Biomolecular and Biomedical Research, University College Dublin, Dublin, Ireland. m.al-rubeai@ucd.ie.
authors.forename: Mohamed
authors.initials: M
authors.lastname: Al-Rubeai
mesh_terms: D000818:Animals; D000911:Antibodies, Monoclonal / Q000096:biosynthesis*; D016466:CHO Cells; D058543:Class Ia Phosphatidylinositol 3-Kinase / Q000378:metabolism*; D003412:Cricetulus; D011994:Recombinant Proteins / Q000096:biosynthesis*; D015398:Signal Transduction; D058570:TOR Serine-Threonine Kinases / Q000378:metabolism*; D059467:Transcriptome
chemical_list: D000911:Antibodies, Monoclonal; D011994:Recombinant Proteins; D058543:Class Ia Phosphatidylinositol 3-Kinase; D058570:TOR Serine-Threonine Kinases