Mitotic events in cerebellar granule progenitor cells that expand cerebellar surface area are critical for normal cerebellar cortical lamination in mice.
Mitotic events in cerebellar granule progenitor cells that expand cerebellar surface area are critical for normal cerebellar cortical lamination in mice.
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DOI：
10.1097/nen.0000000000000171
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发表时间：
2015-03
影响因子：
3.2
通讯作者：
Otero JJ
中科院分区：
文献类型：
--
作者：
Chang JC;Leung M;Gokozan HN;Gygli PE;Catacutan FP;Czeisler C;Otero JJ
胚胎晚期和出生后的小脑叶片表面积扩展促进小脑皮质细胞构筑分层。我们开发了一种简化的取样方案，利用体视学原理对小鼠小脑表面积和体积进行无偏估计。我们证明，在外部颗粒层（EGL）的增殖阶段以及叶片表面积扩展期间，EGL厚度不变，因此它是祖细胞自我更新的拓扑替代指标。拓扑约束表明，在增殖阶段，从EGL迁出与自我更新是平衡的。因此，祖细胞自我更新必须包括产生同一层中2个细胞以增加表面积的有丝分裂事件（β事件）以及产生2个细胞且1个细胞在浅层、1个细胞在深层的有丝分裂事件（α事件）。因此，随着小脑的生长，β事件位于α事件的上游。利用一个受体积和表面积测量值约束的数学模型，我们能够在出生后小鼠小脑以单个细胞为基础量化β事件的有丝分裂间期。此外，我们发现CCNA2的缺失会减少EGL增殖并继发性地导致小脑皮质分层异常，但α型事件得以保留。因此，CCNA2缺失的小脑颗粒祖细胞能够对EGL干细胞微环境进行自我更新；这与之前在CCNA2缺失小鼠中发现的大量细胞凋亡是一致的。类似的方法可能为体视学研究结果的解释提供另一层面的深度。
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 stereological principles. We demonstrate that during the proliferative phase of the external granule 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 either 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 inter-mitotic times for β-events on a per-cell basis in post-natal 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 stereological studies.