MicroRNAs as Engineering Targets: Pathway Manipulation to Impact Bioprocess Phenotypes - MicroRNAs as Tools in Biopharmaceutical Production - page 65

Chapter 5
MicroRNAs as Engineering Targets: Pathway
Manipulation to Impact Bioprocess Phenotypes

Aliaksandr Druz, Michael Betenbaugh and Joseph Shiloach

Abstract Chinese hamster ovary (CHO) cells are the primary mammalian culture
system used for recombinant protein production; therefore there are continuous
research and development efforts to improve cell production capabilities by both
genetic modification and process optimization strategies. The genetic modifications
are used to increase specific growth rate, to reduce apoptosis and to improve nu-
trients utilization. Since altering the expression of a single gene or even a single
pathway may not be sufficient to produce desirable phenotypes, regulation of global
gene expression may be a better approach for pathway engineering in CHO cells.
miRNA(s) were found to be global regulators of gene expression with the ability to
simultaneously alter multiple cellular pathways such as cell growth, apoptosis, stress
resistance, metabolism and protein secretion. Therefore, modifications of miRNA
expression profiles may facilitate the design of high-producing CHO cells. Recent ad-
vances in transfection techniques allow the insertion of miRNA mimics or inhibitors
into CHO cells at specific stages of the bioprocess. Unlike traditional engineering
approaches, manipulation of miRNA expression profiles does not burden the transla-
tional machinery of the cell and therefore, cellular metabolic resources are allocated
to recombinant protein production. In this chapter we highlight the industrially-
relevant pathways, report on miRNA involvement in their regulation, discuss how
these miRNAs can be used to improve performance of CHO cells for industrial
applications and propose specific miRNA candidates for CHO cell engineering.

Keywords Apoptosis · Mammalian cells · miRNA · Protein expression

J. Shiloach ( )
9000 Rockville Pike Bldg 14A Rm 173, Bethesda, MD 20892, USA
e-mail: [e-mail]
A. Druz

J. Shiloach
Biotechnology Core Laboratory NIDDK,
NIH Bldg 14A, Bethesda, MD 20892, USA
A. Druz

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M. Betenbaugh
Department of Chemical and Biomolecular Engineering, Johns Hopkins University,
Baltimore, MD 21218, USA

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