3 years ago

miR-CATCH identifies biologically active miRNA regulators of the pro-survival gene XIAP, in Chinese hamster ovary cells

Niall Barron, Paul S Kelly, Martin Clynes, Catherine M Greene, Alan Griffith, Sebastian Vencken, Nga T Lao
Genetic engineering of mammalian cells is of interest as a means to boost bio-therapeutic protein yield. X-linked inhibitor of apoptosis (XIAP) overexpression has previously been shown to enhance CHO cell growth and prolong culture longevity while additionally boosting productivity. We confirmed this across a range of recombinant products (SEAP, EPO and IgG). However, stable over-expression of an engineering transgene competes for the cells translational machinery potentially compromising product titre. MicroRNAs are attractive genetic engineering candidates given their non-coding nature and ability to regulate multiple genes simultaneously, thereby relieving the translational burden associated with stable overexpression of a protein-encoding gene. The large number of potential targets of a single miRNA, falsely predicted in-silico, presents difficulties in identifying those that could be useful engineering tools. We explored the identification of direct miRNA regulators of the pro-survival endogenous XIAP gene in CHO-K1 cells by using a miR-CATCH protocol. A biotin-tagged antisense DNA oligonucleotide for XIAP mRNA was designed and used to pull down and capture bound miRNAs. Two miRNAs were chosen out of the 14 miRNAs identified for further validation, miR-124-3p and miR-19b-3p. Transient transfection of mimics for both resulted in the diminished translation of endogenous CHO XIAP protein whereas their inhibition increased XIAP protein levels. A 3'UTR reporter assay confirmed miR-124-3p to be a bona fide regulator of XIAP in CHO-K1 cells. This method demonstrates a useful approach to finding miRNA candidates for CHO cell engineering without competing for the cellular translational machinery.

Publisher URL: http://onlinelibrary.wiley.com/resolve/doi

DOI: 10.1002/biot.201700299

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