Perturbation of canonical and non-canonical BMP signaling affects migration, polarity and dendritogenesis of mouse cortical neurons.

Bone morphogenetic protein (BMP) signaling has been implicated in the regulation of patterning of the forebrain and as a regulator of neurogenesis and gliogenesis in the mammalian cortex. However, its role in other aspects of cortical development in vivo remains unexplored. We hypothesized that BMP signaling might regulate additional processes during the development of cortical neurons after observing active BMP signaling in a spatiotemporally dynamic pattern in the mouse cortex. Our investigation revealed that BMP signaling specifically regulates the migration, polarity and the dendritic morphology of upper layer cortical neurons born at E15.5. On further dissection of the role of canonical and non-canonical BMP signaling in each of these processes, we found that migration of these neurons is regulated by both pathways. Their polarity, however, appears to be affected more strongly by canonical BMP signaling, whereas dendritic branch formation appears to be somewhat more strongly affected by LIMK-mediated non-canonical BMP signaling.