MicroRNAs as Engineering Targets: Pathway Manipulation to Impact Bioprocess Phenotypes - MicroRNAs as Tools in Biopharmaceutical Production - page 80

5.4 Conclusions

In this chapter we reviewed the potential role of miRNAs in CHO cell engineering
for industrial applications based on their involvement in regulation of relevant path-
ways in other cellular systems. Table 5.1 summarizes the effects of the reviewed
miRNAs on relevant cellular pathways and targeted genes in various systems. The
recent work on CHO miRNA transciptome sequencing (Hackl et al. 2011 ; Johnson
et al. 2011 ) allowed detection of more than 80 % of all miRNAs shown in Table 5.1 .
Only a few miRNAs have been studied in CHO cells so far: miR-7, miR-21/24 and
miR-466h. The potential use of miR-7 and miR-466h has already been established
by the manipulation of their expression levels in CHO (Druz et al. 2011 ; Barron et al.
2011b ). Other promising individual miRNAs for CHO cell engineering include those
involved in regulation of multiple pathways: miRs 15a and 16, miRs 17-5p and 20a,
miRs 221 and 222, miR-34 family, miR-21, miR-31, miR-107, miR-124a, miR-204,
miR-210, miR-296, and miR-375. The availability of the CHO cell genome sequence
and the creation of CHO-specific genomic and proteomic tools will help to explore
the activity of these miRNAs and to identify their targets. Another approach is to
re-engineer (over-express or knock down) whole miRNA clusters already reported
to be involved in relevant pathways such as miR 15a/16, miR 221/222, miR 144/451,
miR 17-92, and miR-34b/c clusters. Also, clusters that incorporate the individual
miRs shown in Table 5.1 , such as miR 297-669, miR-296/298, miR 23-27 (in-
clude miR-466h, miR-296, and miR-23a respectively) need to be considered for the
generation of robust CHO cell lines.

Acknowledgments Funding was provided by the intramural program of the National Institute of
Diabetes and Digestive and Kidney Diseases, National Institutes of Health. The authors would like
to thank Mrs. D. Livnat and Mrs. A Shiloach for critical review of the manuscript.

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