Biology Reference
In-Depth Information
several hypotheses exist including mRNA cleavage, deadenylation,
degradation, p-body recruitment, and blocking of various transla-
tional initiation steps [
11
,
35
].
Due to the complex nature of this biogenesis cascade, there are
several sites for therapeutic intervention; however this chapter spe-
cifi cally focuses on the regulation of miRNA maturation rather
than simply targeting the mature miRNA [
36
]. Depending on the
target and type of therapeutic this can be achieved in either a spe-
cifi c fashion (only affecting a single miRNA) or a nonspecifi c fash-
ion (affecting the entire pathway and thus all cellular miRNAs).
Both approaches have distinct advantages and disadvantages, as
specifi c targeting is often challenging to achieve but has minimized
deleterious off-target effects [
37
]. Conversely, global targeting is
easier to accomplish but requires additional considerations to
deliver the therapeutic to only the desired cells in order to avoid
miRNA misregulation in healthy cells. In either case, the ability to
target miRNA maturation represents not only a viable approach to
achieving a better understanding of the miRNA pathway but also a
useful mechanism to treat conditions associated with misregulated
miRNA and thus misregulated gene expression.
Moreover, the elucidation of valid maturation inhibitors can
be accomplished via the development of either in vitro or in vivo
assays/screens. While in vitro assays are often easier to establish
and more directly target a specifi c component of the maturation
pathway, they can sometimes be diffi cult to recapitulate when the
active hits are translated to an in vivo system [
38
]. On the other
hand, in vivo assays are often more complex to establish and require
a deconvolution step to ascertain the actual target of the effector
molecule; however, they are already established within biological
systems and deliver more robust “hits.” [
39
] This chapter exam-
ines both in vitro and in vivo approaches to miRNA maturation at
each step in the biogenesis process to highlight the innovative
research that has been conducted, affording new chemical tools to
control this important biological process.
2
Manipulation of Pri-miRNA Maturation
The ability to modulate the level of pri-miRNA either by transcrip-
tional regulation or direct binding to the tertiary structure of
pri-miRNA represents a mechanism to achieve a higher level of
specifi city than targeting further downstream in the biogenesis
pathway. Consequently, targeting of pri-miRNA can be achieved
via both in vivo and in vitro assays depending on the choice of
regulatory molecule (small molecule or biomacromolecule).
Preventing the further maturation of pri-miRNA affords the ability
to signifi cantly decrease cellular concentrations of miRNAs and
thus has signifi cant therapeutic value.
