Spag17 Deficiency Impairs Neuronal Cell Differentiation in the Developing Brain
The development of the nervous system is a multi-level, time-sensitive process that relies heavily on cell signaling. However, the molecular mechanisms that control brain development remain poorly understood. We generated a knockout (KO) mouse for the cilia associated gene Spag17. These animals develop hydrocephalus and enlarged ventricles consistent with the role of Spag17 in the motility of ependymal cilia. However, other phenotypes that cannot be explained by this role were also present. Recently, a mutation in Spag17 has been associated with brain malformations and severe intellectual disability in humans. Therefore, we hypothesized that Spag17 plays a crucial role in nervous system development. To investigate this possibility, we first characterized the spatiotemporal expression of Spag17 in the developing brain by using Beta-galactosidase staining and immunohistochemistry. Results showed Spag17 expression in the spinal cord as early as embryonic E11. By E11.5-12.5 the expression extends to the rhombic lip from the developing hindbrain, as well as to the forebrain and midbrain regions. E14.5-15.5 embryos exhibit an intense expression in the developing ventricles as well as the cerebellum. From E17.5 to birth (P0), the gene is more broadly expressed. We then used a global Spag17 KO mouse model was used to characterize the function of Spag17 during brain development. Immunohistochemical studies performed in brain sections from E15.5 and P0 time points showed increased expression of the neural progenitor marker Nestin, reduced expression of mature neuron marker NeuN, increasing positive trend with the young neuron marker Tuj1. Altogether, these findings reveal that Spag17 has a unique spatiotemporal distribution and may be critical for the maturation of neural progenitor cells.