miRNA interference (miRNAi) is a new concept that I proposed for the development of strategies and
technologies to manipulate the function, stability, biogenesis, or expression of miRNAs and as such it indirectly
interferes with expression of protein-coding mRNAs. This chapter aims to give an implicitly detailed introduction
to some of the miRNAi strategies and technologies developed so far. The fundamental mechanism of miRNA
regulation of gene expression is miRNA:mRNA interaction or binding. A key to interfere with miRNA actions is
to disrupt the miRNA:mRNA interaction. In order to achieve this aim, one can either manipulate miRNAs or
mRNAs to alter the miRNA:mRNA interaction. For miRNAs, one can either mimic miRNA actions to enhance
the miRNA:mRNA interaction or to inhibit miRNAs to break the miRNA:mRNA interaction. Both gain-offunction
and loss-of-function technologies are necessary tools for understanding miRNAs. The miRNAi
technologies have opened up new opportunities for creative and rational designs of a variety of combinations
integrating varying nucleotide fragments for various purposes and provided exquisite tools for functional analysis
related to identification and characterization of targets of miRNAs and their functions in gene controlling
program. In addition, the miRNAi technologies also offer the strategies and tools for designing new agents for
gene therapy of human disease.
