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Dev Biol 2011 Jan 15;3492:378-86. doi: 10.1016/j.ydbio.2010.10.030.
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Nkx6 genes pattern the frog neural plate and Nkx6.1 is necessary for motoneuron axon projection.

Dichmann DS , Harland RM .

Neuronal subtypes originate from an undifferentiated neural epithelium that is progressively divided into progenitor domains by homeodomain transcription factors such as members of the Nkx family. Here we report the functional analysis of Nkx6.1 and Nkx6.2 in Xenopus. While Nkx6.2 is expressed early in a large region of the medial neural plate, Nkx6.1 is restricted to a region overlapping with the region of motor neuron formation. By mRNA injection we show that both can inhibit primary neurogenesis as well as expression of intermediate neural plate markers. However, they do not form auto-regulatory loops and fail to induce ectopic motor neurons as they do in the chick. Using morpholino-mediated knockdown in Xenopus laevis and Xenopus tropicalis we show that Nkx6.1 knockdown results in paralyzed tadpoles. Using DiI labeling and immunohistochemistry we show that the underlying mechanism is a failure of spinal motor neurons to extend axons to their targets. Analysis of neural pattern reveals that ventral Lhx3+ and Pax2+ interneurons are dependent on Nkx6.1 function, but overall neural patterning is not. This study illustrates that while important aspects of Nkx6 gene function are conserved in vertebrate neural patterning, others are not.

PubMed ID: 21035438
PMC ID: PMC3018535
Article link: Dev Biol
Grant support: [+]

Species referenced: Xenopus tropicalis Xenopus laevis
Genes referenced: dbx1 irx3 krt12.4 lhx3 mnx1 msx1 ncam1 nkx6-1 nkx6-2 nrp1 pax2 pax3 pax6 sox2 tubb2b
Antibodies: Ncam1 Ab2 Nkx6-1 Ab1
Morpholinos: nkx6-1 MO1 nkx6-1 MO2

Article Images: [+] show captions
References [+] :
Briscoe, A homeodomain protein code specifies progenitor cell identity and neuronal fate in the ventral neural tube. 2000, Pubmed