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Regulation of XBP‐1 signaling during transient and stable recombinant protein production in CHO cells
Author(s) -
Ku Sebastian C. Y.,
Toh Poh Choo,
Lee Yih Yean,
Chusainow Janet,
Yap Miranda G. S.,
Chao ShengHao
Publication year - 2009
Publication title -
biotechnology progress
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.572
H-Index - 129
eISSN - 1520-6033
pISSN - 8756-7938
DOI - 10.1002/btpr.322
Subject(s) - chinese hamster ovary cell , recombinant dna , unfolded protein response , microbiology and biotechnology , biology , gene isoform , cell culture , endoplasmic reticulum , intracellular , signal transduction , regulator , protein biosynthesis , activator (genetics) , biochemistry , gene , genetics
X‐box binding protein 1 (XBP‐1) is a key regulator of cellular unfolded protein response (UPR). The spliced isoform of XBP‐1, XBP‐1S, is a transcription activator, which is expressed only when UPR is induced. However, the impact of recombinant protein production on the regulation of XBP‐1 signaling in CHO cells is not well understood. In this report, we cloned the Chinese hamster XBP‐1 homolog to aid the investigation of the interplay between protein productivity, culture conditions, and endogenous XBP‐1 signaling in CHO cells. Interestingly, expression of XBP‐1S is detected in the non‐producing and unstressed CHO‐K1 cells. Transient expression of recombinant erythropoietin reveals a positive correlation between XBP‐1 mRNA abundance and protein production level. However, such a correlation is not observed in batch cultivation of stable producing cell lines. The increased XBP‐1 splicing is detected in late‐phase cultures, suggesting that induction of XBP‐1S may be a result of nutrient limitations or other environmental stresses rather than that of increased intracellular accumulation of recombinant proteins. Our data suggest that XBP‐1 is a key determinant for the secretory capacity of CHO cells. Understanding its dynamic regulation hence provides a rational basis for cellular engineering strategies to improve recombinant protein secretion. © 2009 American Institute of Chemical Engineers Biotechnol. Prog., 2010