Biology Reference
In-Depth Information
2010
;
Rodriguez
et al
., 2007
;
Vigorito
et al
., 2007
;
Xiao
et al
., 2007
;
Yekta
et al
., 2004
). Although there are clearly exceptions to these types of
miRNA regulation in the hematopoietic system, these appear to be the
most commonly targeted nodes in the molecular networks that control
blood cell development.
Novel and exciting aspects of miRNA biology are continuing to unfold.
For instance, recent evidence suggests that miRNAs are involved in inter-
cellular regulatory mechanisms. Microvesicles, or exosomes, found in the
serum are loaded with mature miRNAs (
Hunter
et al
., 2008
). Many cancer
cells, including those of hematopoietic origin, have been shown to release
exosomes containing miRNAs (
Zhang
et al
., 2010
). While these offer
important diagnostic opportunities, their roles during normal physiology
are currently being evaluated. Such a system could allow for a cell to
downregulate genes in a neighboring or distal cell type, making miRNAs
important mediators of communication between cells.
Another emerging role for miRNAs is in the production of induced
pluripotent stem (iPS) cells. Specific miRNAs are able to replace the iPS factor
cMyc during the conversion of mature cells into iPS cells (
Judson
et al
., 2009
).
The ability to reverse hematopoietic development using biotechnology has
many practical and clinically important applications, and recent evidence
indicates that this is also possible (
Eminli
et al
., 2009
). As we begin to learn
more about which miRNAs are important for hematopoiesis, we may be able
to exploit their programming to direct mature immune cells back into iPS cells
and/or HSCs. Additionally, cells that make up the immune system appear to
have great developmental plasticity, and miRNAs might be used to skew
immune cells from one lineage to another.
Taken together, miRNAs represent a promising frontier in the arena of
mammalian hematopoiesis and molecular biology in general. Although it is
becoming clear that miRNAs are integral components of the signaling
networks underlying blood cell development, the field is young and thus
the identity and function of many hematopoietically relevant miRNAs and
other ncRNAs remain unknown. Identifying and characterizing miRNAs
and other ncRNAs involved in these fields of study will be important for the
progress of basic science, including our understanding of blood cell devel-
opment. Additionally, continued advancement in these areas will undoubt-
edly reveal novel biomarkers and therapeutic targets to be used in the
diagnosis and treatment of hematological diseases.
ACKNOWLEDGMENTS
R. M. O. was funded by award number 4R00HL102228-03 from the National Heart, Lung
and Blood Institute. This work was also supported by NIH Grant 1R01AI079243-01.
