A fully differentiated cell took a fascinating journey to become its present self. For every cell, a precursor cell existed that gave rise to it. And for every precursor cell, a stem cell existed that gave rise to it. In fact, many have discussed the fuzzy gray area in the distinction between “stem cell” and “precursor,” as they can share many characteristics. Understanding how precursor cells arise and divide is important in understanding stem cell biology. Today’s image is from a recent paper in Development that discusses how neuron precursor divisions affect brain development.
The cerebral cortex is the outermost layer or brain tissue, and is commonly referred to as “gray matter.” During brain development, precursor cell divisions result in the formation of the many different regions and layers found in the cerebral cortex. These precursor cells arise from radial glial cells, which arise from neural stem cells. The different layers of the cerebral cortex are formed by the migration of neurons that were freshly-produced by precursor cells. Neurons that complete a cell division earlier are able to migrate further, while neurons that take longer to complete cell division aren’t able to migrate as far. Exploring this connection between the cell cycle and formation of cortex layers, Mairet-Coello and colleagues recently published results showing how cell cycle regulators can affect the development of the different layers. Specifically, two different proteins called cyclin-dependent kinase inhibitors regulate the cell cycle length of precursor cells, and in turn affect neuron development in the lower and upper layers of the cerebral cortex. In the images above, one of these cyclin kinase inhibitors, p57KIP2(red), was found in actively dividing precursor cells (green) in two different zones in the developing mouse brain, labeled SV and SVZ. Dividing cells that have p57KIP2 protein are yellow in the merged image (arrows).
For a more scientifically detailed description of this image, check out my post on The Node, the community forum for and by developmental biologists.
