The Chromatin Remodelling Contributions of Snf2l in Cerebellar Granule Neuron Differentiation [RNA-Seq]. The Chromatin Remodelling Contributions of Snf2l in Cerebellar Granule Neuron Differentiation [RNA-Seq]

Snf2l and the closely related protein, Snf2h, play a critical role in embryonic and post-natal brain development. Murine models lacking functional Snf2h or Snf2l point to complementary activities of these remodelers; Snf2h cKO mice present with a significantly reduced cerebellum, while Snf2l Ex6DEL cerebella are larger than their wild-type counterparts. Granule neuron progenitors (GNPs) isolated from Ex6DEL cerebella display delayed cell cycle exit and hindered terminal differentiation compared to wild-type littermates. Moreover, loss of Snf2l activity results in widespread transcriptome shifts which underlie the Ex6DEL GNP differentiation phenotype. In particular, key transcription factors (TFs) are differentially expressed without Snf2l remodelling activity. We confirm that ERK pathway activation is misregulated in Ex6DEL GNPs, possibly in response to elevated fibroblast growth factor 8 (Fgf8) expression in these cultures. We find that Snf2l activity maintains the chromatin landscape throughout GNP differentiation, as Ex6DEL cultures have a global increase in chromatin accessibility. We suggest that Snf2l-mediated chromatin condensation is responsible for proper regulation of gene expression programs in GNP differentiation. Overall design: Assess modifications in chromatin accessibility upon loss of Snf2l activity (Ex6DEL)

Snf2l与紧密相关的同源蛋白Snf2h在胚胎发育及出生后脑发育过程中发挥关键调控作用。敲除功能性Snf2h或Snf2l的小鼠模型证实，两类染色质重塑因子的功能存在互补性：Snf2h条件性敲除（conditional knockout, cKO）小鼠的小脑体积显著缩小，而Snf2l Ex6DEL小鼠的小脑则大于其野生型同窝对照。从Snf2l Ex6DEL小鼠小脑分离得到的颗粒神经元祖细胞（Granule Neuron Progenitors，GNPs），与野生型同窝小鼠来源的细胞相比，表现出细胞周期退出延迟及终末分化受阻的表型。此外，Snf2l活性缺失会引发广泛的转录组改变，这正是Ex6DEL GNPs分化异常表型的分子基础。具体而言，关键转录因子（Transcription Factors，TFs）的表达在Snf2l重塑活性缺失时出现显著差异。我们证实，ERK信号通路的激活在Ex6DEL GNPs中存在调控紊乱，该现象可能与培养体系中成纤维细胞生长因子8（Fibroblast Growth Factor 8，Fgf8）的表达上调相关。研究发现，Snf2l活性可维持颗粒神经元祖细胞分化全程的染色质景观，而Ex6DEL培养体系的染色质可及性呈全局升高趋势。据此我们提出，Snf2l介导的染色质浓缩过程负责精准调控颗粒神经元祖细胞分化中的基因表达程序。实验整体设计：评估Snf2l活性缺失（Ex6DEL）状态下染色质可及性的变化。