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Echinobase
ECB-ART-42404
Dev Biol 2012 Apr 15;3642:259-67. doi: 10.1016/j.ydbio.2012.02.003.
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Cis-regulatory logic driving glial cells missing: self-sustaining circuitry in later embryogenesis.

Ransick A , Davidson EH .


Abstract
The glial cells missing (gcm) regulatory gene of the sea urchin Strongylocentrotus purpuratus is first expressed in veg2 daughter cells as the genomic target of late cleavage stage Delta-Notch signaling from the skeletogenic mesoderm precursors. Gcm is required in veg2 progeny during late cleavages for the early phase of pigment cell precursor specification. Here we report on a later acting cis-regulatory module that assumes control of gcm expression by the early mesenchyme blastula stage and maintains it through pigment cell differentiation and dispersal. Cis-perturbation analyses reveal that the two critical elements within this late module are consensus matches to Gcm and Six1 binding sites. Significantly, six1 mRNA localizes to gcm+cells from the mesenchyme blastula stage onwards. Trans-perturbations with anti-sense morpholinos reveal a co-dependency between six1 and gcm. Six1 mRNA levels fall sharply after Gcm is depleted, while depleting Six1 leads to significant reductions in output of endogenous gcm or modular-reporters. These results support the conclusion gcm and six1 comprise a positive intergenic feedback loop in the mesodermal GRN. This often employed cross regulatory GRN feature here ensures self-sustaining gcm output in a cohort of fully specified pigment cell precursors at a relatively early developmental stage.

PubMed ID: 22509525
PMC ID: PMC3561781
Article link: Dev Biol
Grant support: [+]

Genes referenced: gcml LOC100887844 LOC115919910 LOC115921237 LOC575170 six1
Morpholinos: LOC575231 MO1 gcml MO1 six1 MO2

References [+] :
Arnone, Using reporter genes to study cis-regulatory elements. 2004, Pubmed, Echinobase