PQBP1 regulates striatum development through balancing striatal progenitor proliferation and differentiation

The balance between cell proliferation and differentiation is essential for maintaining the neural progenitor pool and brain development. Although the mechanisms underlying cell proliferation and differentiation at the transcriptional level have been studied intensively, post-transcriptional regulation of cell proliferation and differentiation remains largely unclear. Here, we show that deletion of the alternative splicing regulator PQBP1 in striatal progenitors resulted in defective striatal development due to impaired neurogenesis of spiny projection neurons (SPNs). Pqbp1 deficiency striatal progenitors exhibit declined proliferation and increased differentiation, resulting in a reduced striatal progenitor pool. We further reveal that PQBP1 associates with components in splicing machinery. The alternative splicing profiles identify that PQBP1 promotes the exon 9 inclusion of Numb, a variant that mediates progenitor proliferation. These findings identify PQBP1 as a novel regulator in balancing striatal progenitor proliferation and differentiation and provide alternative insights into the pathogenic mechanisms underlying Renpenning syndrome. Total RNA from the Isolating the strong GFP-positive striatal IPs at E15.5 Pqbp1+/Y;Dlx5/6-Cre-IRES-EGFP and Pqbp1fl/Y;Dlx5/6-Cre-IRES-EGFP mice by using fluorescence-activated cell sorting (FACS) extracted for deep sequencing, in triplicate, using Illumina HiSeq X Ten.细胞增殖与分化的平衡对于维持神经前体细胞池及脑发育至关重要。尽管学界已对转录水平上调控细胞增殖与分化的潜在机制展开了深入研究，但细胞增殖与分化的转录后调控机制仍在很大程度上尚不明确。本研究发现，在纹状体前体细胞中敲除可变剪接调控因子多聚谷氨酰胺结合蛋白1（polyglutamine binding protein 1, PQBP1），会因棘突投射神经元（spiny projection neurons, SPNs）的神经发生受损而引发纹状体发育缺陷。Pqbp1缺陷型纹状体前体细胞表现为增殖能力下降、分化水平升高，进而导致纹状体前体细胞池缩减。我们进一步揭示，PQBP1可与剪接机器的组分相结合。可变剪接谱分析结果显示，PQBP1能够促进介导前体细胞增殖的Numb基因第9外显子的保留，该剪接变体可调控前体细胞的增殖过程。上述研究结果确定PQBP1为平衡纹状体前体细胞增殖与分化的新型调控因子，并为Renpenning综合征的致病机制提供了全新的研究视角。我们通过荧光激活细胞分选（fluorescence-activated cell sorting, FACS），从妊娠第15.5天（E15.5）的Pqbp1+/Y;Dlx5/6-Cre-IRES-EGFP与Pqbp1fl/Y;Dlx5/6-Cre-IRES-EGFP小鼠中分离得到强GFP阳性的纹状体细胞，提取总RNA并进行三次生物学重复的深度测序，测序平台为Illumina HiSeq X Ten。