An image of the early mouse cranial neural plate (green) and neighboring tissues (magenta). Image credit: Brooks et al. (CC BY 4.0)
Brain development in mammals starts when a sheet of cells rolls into a tube, a process called neural tube closure. Missteps in this process are among the most common structural brain malformations in humans, affecting about one in 2,000 births. Learning more about this dynamic process will help scientists understand why these common neural tube defects occur and elucidate the mysteries of early brain development.
Neural tube closure involves dramatic changes in tissue architecture that require carefully orchestrated changes in cell behavior and gene expression. Scientists have identified many key signals that set these processes in motion. However, an important missing piece was a comprehensive description of the gene expression changes that occur during closure, which provide a blueprint for the developing brain.
Using single-cell RNA sequencing, Brooks et al. assembled a two-dimensional map of the expression of thousands of genes during neural tube closure in the mouse embryo. Starting with a few well-known genes with localized expression patterns, they were able to predict the expression patterns of 870 genes during the process. This map matched known gene expression with high accuracy and predicted expression patterns for hundreds of previously uncharacterized genes. Moreover, they showed that activating a key developmental pathway, known as Sonic hedgehog signaling, dramatically reshaped gene expression along the width and length of the neural tube.
Brooks et al. provide a two-dimensional map of gene expression in the mouse cranial neural plate that will help scientists trace the earliest steps in brain development. This work provides a road map to understanding the processes that generate the remarkable organization and functions of the mammalian brain.
