Goodwin Laura R, Zapata Gerardo, Timpano Sara, Marenger Jacob, Picketts David J
Regenerative Medicine Program, Ottawa Hospital Research Institute, Ottawa, ON, Canada.
Department of Biochemistry, Microbiology and Immunology, University of Ottawa, Ottawa, ON, Canada.
Front Mol Neurosci. 2021 Jul 6;14:680280. doi: 10.3389/fnmol.2021.680280. eCollection 2021.
Chromatin remodeling proteins utilize the energy from ATP hydrolysis to mobilize nucleosomes often creating accessibility for transcription factors within gene regulatory elements. Aberrant chromatin remodeling has diverse effects on neuroprogenitor homeostasis altering progenitor competence, proliferation, survival, or cell fate. Previous work has shown that inactivation of the genes, (encoding Snf2h) and (encoding Snf2l) have dramatic effects on brain development. conditional knockout mice have reduced progenitor expansion and severe forebrain hypoplasia, with a similar effect on the postnatal growth of the cerebellum. In contrast, mutants exhibited enlarged forebrains with delayed progenitor differentiation and increased neuronal output. Here, we utilized cerebellar granule neuron precursor (GNP) cultures from mutant mice (Ex6DEL) to explore the requirement for Snf2l on progenitor homeostasis. The Ex6DEL GNPs showed delayed differentiation upon plating that was not attributed to changes in the pathway but was associated with overexpression of numerous positive effectors of proliferation, including targets of Wnt activation. Transcriptome analysis identified increased expression of and while ATACseq experiments identified a large increase in chromatin accessibility at promoters many enriched for Fos/Jun binding sites. Nonetheless, the elevated proliferation index was transient and the Ex6DEL cultures initiated differentiation with a high concordance in gene expression changes to the wild type cultures. Genes specific to Ex6DEL differentiation were associated with an increased activation of the ERK signaling pathway. Taken together, this data provides the first indication of how mutations alter progenitor cell homeostasis and contribute to changes in brain size.
染色质重塑蛋白利用ATP水解产生的能量来移动核小体，通常会使基因调控元件内的转录因子具有可及性。异常的染色质重塑对神经祖细胞稳态有多种影响，改变祖细胞的能力、增殖、存活或细胞命运。先前的研究表明，基因（编码Snf2h）和基因（编码Snf2l）的失活对大脑发育有显著影响。条件性敲除小鼠的祖细胞扩增减少，前脑严重发育不全，对小脑的出生后生长也有类似影响。相比之下，突变体表现出前脑增大，祖细胞分化延迟，神经元输出增加。在这里，我们利用来自突变小鼠（Ex6DEL）的小脑颗粒神经元前体（GNP）培养物来探索Snf2l对祖细胞稳态的需求。Ex6DEL GNP在接种后显示出分化延迟，这并非归因于通路的变化，而是与许多增殖正效应因子的过表达有关，包括Wnt激活的靶标。转录组分析确定和的表达增加，而ATACseq实验确定启动子处的染色质可及性大幅增加，许多启动子富含Fos/Jun结合位点。尽管如此，升高的增殖指数是短暂的，Ex6DEL培养物开始分化时，基因表达变化与野生型培养物高度一致。Ex6DEL分化特有的基因与ERK信号通路的激活增加有关。综上所述，这些数据首次表明了突变如何改变祖细胞稳态并导致脑大小的变化。
