Molecular regulation of the developing commissural plate.
Coordinated transfer of information between the brain hemispheres is essential for function and occurs via three axonal commissures in the telencephalon: the corpus callosum (CC), hippocampal commissure (HC), and anterior commissure (AC). Commissural malformations occur in over 50 human congenital syndromes causing mild to severe cognitive impairment. Disruption of multiple commissures in some syndromes suggests that common mechanisms may underpin their development. Diffusion tensor magnetic resonance imaging revealed that forebrain commissures crossed the midline in a highly specific manner within an oblique plane of tissue, referred to as the commissural plate. This specific anatomical positioning suggests that correct patterning of the commissural plate may influence forebrain commissure formation. No analysis of the molecular specification of the commissural plate has been performed in any species; therefore, we utilized specific transcription factor markers to delineate the commissural plate and identify its various subdomains. We found that the mouse commissural plate consists of four domains and tested the hypothesis that disruption of these domains might affect commissure formation. Disruption of the dorsal domains occurred in strains with commissural defects such as Emx2 and Nfia knockout mice but commissural plate patterning was normal in other acallosal strains such as Satb2(-/-). Finally, we demonstrate an essential role for the morphogen Fgf8 in establishing the commissural plate at later developmental stages. The results demonstrate that correct patterning of the commissural plate is an important mechanism in forebrain commissure formation.
Moldrich
Randal X
RX
Queensland Brain Institute, University of Queensland, Brisbane, QLD 4072, Australia.
Gobius
Ilan
I
Pollak
Thomas
T
Zhang
Jiangyang
J
Ren
Tianbo
T
Brown
Lucia
L
Mori
Susumu
S
De Juan Romero
Camino
C
Britanova
Olga
O
Tarabykin
Victor
V
Richards
Linda J
LJ
D000818:Animals; D056324:Diffusion Tensor Imaging; D051524:Fibroblast Growth Factor 8 / Q000235:genetics / Q000378:metabolism; D018398:Homeodomain Proteins / Q000235:genetics; D006801:Humans; D007150:Immunohistochemistry; D036961:Matrix Attachment Region Binding Proteins / Q000235:genetics; D051379:Mice; D008810:Mice, Inbred C57BL; D018345:Mice, Knockout; D051839:NFI Transcription Factors / Q000235:genetics; D013687:Telencephalon / Q000002:abnormalities* / Q000033:anatomy & histology* / Q000196:embryology* / Q000378:metabolism; D014157:Transcription Factors / Q000235:genetics; D000099260:Empty Spiracles Homeobox Proteins
D051524:Fibroblast Growth Factor 8; D018398:Homeodomain Proteins; D036961:Matrix Attachment Region Binding Proteins; D051839:NFI Transcription Factors; D014157:Transcription Factors; D000099260:Empty Spiracles Homeobox Proteins; C496457:Fgf8 protein, mouse; C497646:Nfia protein, mouse; C501473:SATB2 protein, mouse