Developmental Biology, 2010, Vol.344(2), pp.1026-1034
During development, commissural neurons in the spinal cord project their axons across the ventral midline, floor plate, via multiple interactions among temporally controlled molecular guidance cues and receptors. The transcriptional regulation of commissural axon-associated receptors, however, is not well characterized. Spinal dorsal cells are transfated into commissural neurons by misexpression of , a Bar-class homeobox gene. We examined the function of another Bar-class homeobox gene, , and how and modulate expression of the receptors, leading to midline crossing of axons. Misexpression of and showed the same effects in the spinal cord. The competence of spinal dorsal cells to become commissural neurons was dependent on the embryonic stage, during which misexpression of the genes was able to activate guidance receptor genes such as and . Misexpression of , which has been recently shown to be involved in expression, activated but not , and was less effective in generating commissural neurons. Moreover, expression of was activated by and required the genes. These findings have revealed a transcriptional cascade, in which -dependent and -independent pathways leading to expression of guidance receptors branch downstream of the genes.
Spinal Cord ; Commissural Neuron ; Guidance Receptor ; Bar-Class Homeobox ; Lim Homeobox ; In Vivo Electroporation ; Biology ; Zoology
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