Monderer-Rothkoff Galya, Tal Nitzan, Risman Marina, Shani Odem, Nissim-Rafinia Malka, Malki-Feldman Laura, Medvedeva Vera, Groszer Matthias, Meshorer Eran, Shifman Sagiv
Department of Genetics, The Institute of Life Sciences, The Hebrew University of Jerusalem, Jerusalem, Israel.
Inserm, UMR-S839, Sorbonne Universités, Pierre et Marie Curie Université Paris 06, Institut du Fer à Moulin, Paris, 75005, France.
Mol Psychiatry. 2021 Feb;26(2):666-681. doi: 10.1038/s41380-019-0409-1. Epub 2019 Apr 5.
Mutations in AUTS2 are associated with autism, intellectual disability, and microcephaly. AUTS2 is expressed in the brain and interacts with polycomb proteins, yet it is still unclear how mutations in AUTS2 lead to neurodevelopmental phenotypes. Here we report that when neuronal differentiation is initiated, there is a shift in expression from a long isoform to a short AUTS2 isoform. Yeast two-hybrid screen identified the splicing factor SF3B1 as an interactor of both isoforms, whereas the polycomb group proteins, PCGF3 and PCGF5, were found to interact exclusively with the long AUTS2 isoform. Reporter assays showed that the first exons of the long AUTS2 isoform function as a transcription repressor, but the part that consist of the short isoform acts as a transcriptional activator, both influenced by the cellular context. The expression levels of PCGF3 influenced the ability of the long AUTS2 isoform to activate or repress transcription. Mouse embryonic stem cells (mESCs) with heterozygote mutations in Auts2 had an increase in cell death during in vitro corticogenesis, which was significantly rescued by overexpressing the human AUTS2 transcripts. mESCs with a truncated AUTS2 protein (missing exons 12-20) showed premature neuronal differentiation, whereas cells overexpressing AUTS2, especially the long transcript, showed increase in expression of pluripotency markers and delayed differentiation. Taken together, our data suggest that the precise expression of AUTS2 isoforms is essential for regulating transcription and the timing of neuronal differentiation.
AUTS2基因的突变与自闭症、智力残疾和小头畸形有关。AUTS2在大脑中表达并与多梳蛋白相互作用，但目前仍不清楚AUTS2基因的突变如何导致神经发育表型。在此我们报告，当神经元分化开始时，AUTS2的表达会从一种长亚型转变为一种短亚型。酵母双杂交筛选确定剪接因子SF3B1是这两种亚型的相互作用蛋白，而多梳蛋白家族蛋白PCGF3和PCGF5仅与AUTS2长亚型相互作用。报告基因检测表明，AUTS2长亚型的第一个外显子起转录抑制因子的作用，但由短亚型组成的部分起转录激活因子的作用，两者均受细胞环境影响。PCGF3的表达水平影响AUTS2长亚型激活或抑制转录的能力。在体外皮质发生过程中，Auts2基因杂合突变的小鼠胚胎干细胞（mESC）细胞死亡增加，而过表达人类AUTS2转录本可显著挽救这种情况。具有截短AUTS2蛋白（缺失外显子12 - 20）的mESC表现出神经元过早分化，而过表达AUTS2，尤其是长转录本的细胞，多能性标志物的表达增加且分化延迟。综上所述，我们的数据表明，AUTS2亚型的精确表达对于调节转录和神经元分化的时间至关重要。
