Proteome dynamics during postnatal mouse corpus callosum development

Formation of cortical connections requires the precise coordination of several discrete stages. This is particularly significant with regard to the corpus callosum, the largest white matter structure bridging both cerebral hemispheres, whose development undergoes several dynamic stages including the crossing of axon projections, the elimination of exuberant projections, and the myelination of established tracts. To comprehensively characterize the molecular events in this dynamic process, we set to determine the distinct temporal expression of proteins regulating the formation of the corpus callosum and their respective developmental functions. Mass spectrometry-based proteomic profiling was performed on early postnatal mouse corpus callosi, for which limited evidence has been obtained previously, using stable isotope of labeled amino acids in mammals (SILAM). The analyzed corpus callosi had distinct proteomic profiles depending on age, indicating rapid progression of specific molecular events during this period. The proteomic expression profiles were then segregated into five separate protein clusters, each with distinct trajectories relevant to their intended developmental functions. Our analysis both confirms many previously-identified proteins in aspects of corpus callosum development, and identifies new candidates in understudied areas of development including callosal axon refinement. We present a valuable resource for identifying new proteins integral to corpus callosum development that will provide new insights into the development and diseases afflicting this structure.