Transcriptional regulation of neural stem cells by Sox genes
Jaesang Kim, Ph.D.
Division of Molecular Life Sciences, Ewha Womans University
During embryonic development, neural stem cells serve to construct the nervous system de
novo while in adults they maintain cellular turnover and respond to restorative demands.
Neural stem cells for both the central nervous system (CNS) and peripheral nervous system
(PNS) have been identified, and distinct intrinsic developmental programs each population
displays have been extensively explored.
Still, molecular mechanisms of their key behaviors,
including self-renewal and differentiation into multiple progeny lineages, have yet to be clearly
understood. During last decade, in vitro culture of neural stem cells and the use of transgenic
animals have transformed the field by allowing genetic manipulation of these cells and
molecular characterization of their development. One group of genes that has been shown to
function as the “stem cell factor” in CNS and PNS neural stem cells is the Sox transcription
factor family members. Sox10 maintains multipotency of neural crest stem cells, the precursor
for the PNS, and inhibits premature neuronal differentiation. Likewise, Sox1, 2, 3 perform
similar tasks for the developing CNS stem cell population in a redundant manner. We can thus
surmise that similar mechanistic logics may be at work in maintaining key attributes of PNS and
CNS stem cells and that extrapolation of results from studying one group of cells can expedite
the understanding of the other group.
In order to define the role of these transcription factors more precisely, we developed a new
protocol for identification of direct regulatory targets of transcription factors.
By
combining RNA interference technique and DNA microarray technology, we have
identified over 50 genes that show a significant down-regulation upon introduction of
Sox 10 shRNA into melanoma cell line.
Importantly, these included genes previously
identified as regulatory target genes of Sox10 in melanocytes. Potential binding sites
for Sox10 were searched within enhancer clusters conserved across several vertebrate
species between -5 Kb to +2 Kb of the transcription initiation sites. Over 30 such
clusters
were
shown
to
be
directly
interacting
with
Sox10
by
chromatin
immunoprecipitation assay leading to identification of multitude of direct Sox10 target
genes.
This protocol requires neither extensive sequencing nor custom designed chips
and thus represents a more economical alternative to other leading methods.