Regulation of XBP-1 signaling during transient and stable recombinant protein production in CHO cells
✍ Scribed by Sebastian C. Y. Ku; Poh Choo Toh; Yih Yean Lee; Janet Chusainow; Miranda G. S. Yap; Sheng-Hao Chao
- Publisher
- American Institute of Chemical Engineers
- Year
- 2009
- Tongue
- English
- Weight
- 885 KB
- Volume
- 26
- Category
- Article
- ISSN
- 8756-7938
- DOI
- 10.1002/btpr.322
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✦ Synopsis
Abstract
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