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of the robustness conferred by both coherent and incoherent FFLs are given
by the role of
mir-7
in photoreceptor and SOP differentiation in
Drosophila.
mir-7
participates in complex interlocking loops and its function is essential
to stabilize the expression of different network components in face of
environmental fluctuations (
Li
et al
., 2009
).
To sum up, addition of a miRNA to an existing gene regulatory
network will have distinct consequences depending on the position of its
target in the network. In some cases, it will provide a switch-like effect to
remove expression of its target and generate a new cellular state, while in
others, it will dampen fluctuations and thus provide robustness to a preex-
isting cellular state
.
5. Concluding Remarks
miRNAs are a class of gene regulatory factors with versatile functions
and as such they have been adopted during the course of evolution to serve a
variety of purposes. During development, miRNAs are a source of robust-
ness and reproducibility; they control spatial and temporal gene expression
to allow for proper patterning and specification of different structures. At
the same time, they provide heritable variability, by diversifying genetic
programs and thus increasing the complexity of any system. Their modes of
action and their molecular properties make them particularly suited to play
regulatory roles in the dynamic cellular environment of the nervous system.
And while their roles are already evidently widespread, we expect to find
them involved in many more.
ACKNOWLEDGMENTS
We sincerely apologize to all those colleagues whose work could not be included due to
space constraints. We thank In´s Carrera, Xantha Karp, Tao Sun, Hynek Wichterle, Jun-An
Chen, and Fiona Doetsch for comments on the chapter. L. C. was funded by the Helen Hay
Whitney Foundation and HHMI. O. H. is an HHMI investigator and is also funded by NIH.
REFERENCES
Alon, U. (2007).
Nat. Rev. Genet.
450-461.
Arvanitis, D. N., Jungas, T., Behar, A., and Davy, A. (2010).
Mol. Cell. Biol.
8,
2508-2517.
Aschrafi, A., Schwechter, A. D., Mameza, M. G., Natera-Naranjo, O., Gioio, A. E., and
Kaplan, B. B. (2008).
J. Neurosci. 28,
12581-12590.
Ashraf, S. I., McLoon, A. L., Sclarsic, S. M., and Kunes, S. (2006).
Cell 124,
191-205.
Asli, N. S., and Kessel, M. (2010).
Dev. Biol. 344,
857-868.
Banerjee, S., Neveu, P., and Kosik, K. S. (2009).
Neuron 64,
871-884.
30,
