Mcidas and GemC1/Lynkeas specify embryonic radial glial cells.

Ependymal cells are multiciliated cells located in the wall of the lateral ventricles of the adult mammalian brain and are key components of the subependymal zone niche, where adult neural stem cells reside. Through the movement of their motile cilia, ependymal cells control the cerebrospinal fluid flow within the ventricular system from which they receive secreted molecules and morphogens controlling self-renewal and differentiation decisions of adult neural stem cells. Multiciliated ependymal cells become fully differentiated at postnatal stages however they are specified during mid to late embryogenesis from a population of radial glial cells. Here we discuss recent findings suggesting that 2 novel molecules, Mcidas and GemC1/Lynkeas are key players on radial glial specification to ependymal cells. Both proteins were initially described as cell cycle regulators revealing sequence similarity to Geminin. They are expressed in radial glial cells committed to the ependymal cell lineage during embryogenesis, while overexpression and knock down experiments showed that are sufficient and necessary for ependymal cell generation. We propose that Mcidas and GemC1/Lynkeas are key components of the molecular cascade that promotes radial glial cells fate commitment toward multiciliated ependymal cell lineage operating upstream of c-Myb and FoxJ1.