title: Mitotic events in cerebellar granule progenitor cells that expand cerebellar surface area are critical for normal cerebellar cortical lamination in mice.
abstract: Late embryonic and postnatal cerebellar folial surface area expansion promotes cerebellar cortical cytoarchitectural lamination. We developed a streamlined sampling scheme to generate unbiased estimates of murine cerebellar surface area and volume using stereologic principles. We demonstrate that, during the proliferative phase of the external granular layer (EGL) and folial surface area expansion, EGL thickness does not change and thus is a topological proxy for progenitor self-renewal. The topological constraints indicate that, during proliferative phases, migration out of the EGL is balanced by self-renewal. Progenitor self-renewal must, therefore, include mitotic events yielding 2 cells in the same layer to increase surface area (β events) and mitotic events yielding 2 cells, with 1 cell in a superficial layer and 1 cell in a deeper layer (α events). As the cerebellum grows, therefore, β events lie upstream of α events. Using a mathematical model constrained by the measurements of volume and surface area, we could quantify intermitotic times for β events on a per-cell basis in postnatal mouse cerebellum. Furthermore, we found that loss of CCNA2, which decreases EGL proliferation and secondarily induces cerebellar cortical dyslamination, shows preserved α-type events. Thus, CCNA2-null cerebellar granule progenitor cells are capable of self-renewal of the EGL stem cell niche; this is concordant with prior findings of extensive apoptosis in CCNA2-null mice. Similar methodologies may provide another layer of depth to the interpretation of results from stereologic studies.
authors: From the Department of Pathology, Division of Neuropathology, The Ohio State University College of Medicine (ML, HNG, PEG, FPC, CC, JJO); and Mathematical Biosciences Institute, The Ohio State University (JCC), Columbus, Ohio.
authors: Joshua C
authors: JC
authors: Chang
authors: Mark
authors: M
authors: Leung
authors: Hamza Numan
authors: HN
authors: Gokozan
authors: Patrick Edwin
authors: PE
authors: Gygli
authors: Fay Patsy
authors: FP
authors: Catacutan
authors: Catherine
authors: C
authors: Czeisler
authors: José Javier
authors: JJ
authors: Otero
mesh_terms: D000818:Animals; D000831:Animals, Newborn; D002465:Cell Movement / Q000502:physiology*; D002525:Cerebellar Cortex / Q000166:cytology* / Q000254:growth & development* / Q000378:metabolism; D002531:Cerebellum / Q000166:cytology / Q000254:growth & development / Q000378:metabolism; D056751:Cyclin A2 / Q000172:deficiency*; D005260:Female; D051379:Mice; D018345:Mice, Knockout; D008938:Mitosis / Q000502:physiology*; D011247:Pregnancy; D013234:Stem Cells / Q000502:physiology*
chemical_list: C508184:CCNA2 protein, mouse; D056751:Cyclin A2