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Dev Biol 2012 Feb 01;3621:65-75. doi: 10.1016/j.ydbio.2011.11.016.
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Xaml1/Runx1 is required for the specification of Rohon-Beard sensory neurons in Xenopus.

Park BY , Hong CS , Weaver JR , Rosocha EM , Saint-Jeannet JP .

Lower vertebrates develop a unique set of primary sensory neurons located in the dorsal spinal cord. These cells, known as Rohon-Beard (RB) sensory neurons, innervate the skin and mediate the response to touch during larval stages. Here we report the expression and function of the transcription factor Xaml1/Runx1 during RB sensory neurons formation. In Xenopus embryos Runx1 is specifically expressed in RB progenitors at the end of gastrulation. Runx1 expression is positively regulated by Fgf and canonical Wnt signaling and negatively regulated by Notch signaling, the same set of factors that control the development of other neural plate border cell types, i.e. the neural crest and cranial placodes. Embryos lacking Runx1 function fail to differentiate RB sensory neurons and lose the mechanosensory response to touch. At early stages Runx1 knockdown results in a RB progenitor-specific loss of expression of Pak3, a p21-activated kinase that promotes cell cycle withdrawal, and of N-tub, a neuronal-specific tubulin. Interestingly, the pro-neural gene Ngnr1, an upstream regulator of Pak3 and N-tub, is either unaffected or expanded in these embryos, suggesting the existence of two distinct regulatory pathways controlling sensory neuron formation in Xenopus. Consistent with this possibility Ngnr1 is not sufficient to activate Runx1 expression in the ectoderm. We propose that Runx1 function is critically required for the generation of RB sensory neurons, an activity reminiscent of that of Runx1 in the development of the mammalian dorsal root ganglion nociceptive sensory neurons.

PubMed ID: 22173066
PMC ID: PMC3257842
Article link: Dev Biol
Grant support: [+]

Species referenced: Xenopus laevis
Genes referenced: astl2c astl3a.1 ccndx cdkn1a egr2 fgf8 isl1 kcna1 neurog2 notch1 npb nsg1 pak1 pak3 pax3 runx1 snai2 tbx2 tub tubb2b zic1
Antibodies: H3f3a Ab9
Morpholinos: ctnnb1 MO1 fgf8 MO1 pax3 MO4 runx1 MO1 runx1 MO2 runx1 MO3 wnt8a MO1 zic1 MO1

Article Images: [+] show captions
References [+] :
Ahrens, Tissues and signals involved in the induction of placodal Six1 expression in Xenopus laevis. 2005, Pubmed, Xenbase