CNKSR2, a downstream mediator of retinoic acid signaling, modulates the Ras/Raf/MEK pathway to regulate patterning and invagination of the chick forebrain roof plate

During embryonic development, the forebrain roof plate undergoes invagination, leading to separation of the cerebral hemispheres. Any defects in this process, in humans, lead to middle interhemispheric holoprosencephaly (MIH-HPE). In this study, we have identified a previously unreported downstream mediator of retinoic acid (RA) signaling, CNKSR2, which is expressed in the forebrain roof plate in the chick embryo. Knockdown of CNKSR2 affects invagination, cell proliferation and patterning of the roof plate, similar to the phenotypes observed upon inhibition of RA signaling. We further demonstrate that CNKSR2 functions by modulating the Ras/Raf/MEK signaling. This appears to be crucial for patterning of the forebrain roof plate and its subsequent invagination, leading to the formation of the cerebral hemispheres. Thus, a set of novel molecular players have been identified that regulate the morphogenesis of the avian forebrain.

Automated summary

During embryonic development, defects in the invagination process of the forebrain roof plate, caused by CNKSR2 knockdown, result in middle interhemispheric holoprosencephaly (MIH-HPE) in humans. CNKSR2 functions by modulating the Ras/Raf/MEK signaling, crucial for patterning and invagination of the forebrain roof plate and the formation of the cerebral hemispheres. This study identifies a novel downstream mediator of retinoic acid signaling and sheds light on the molecular players involved in avian forebrain morphogenesis.