The Scalloped and Nerfin-1 transcription factors cooperate to maintain neuronal cell fate. The Scalloped and Nerfin-1 transcription factors cooperate to maintain neuronal cell fate

The ability of cells to stably maintain their fate is governed by specific transcription regulators. Here, we show that the Scalloped (Sd) and Nervous fingers-1 (Nerfin-1) transcription factors physically and functionally interact to maintain medulla neuron fate in the Drosophila melanogaster CNS. Using Targeted DamID we find that Sd and Nerfin-1 occupy a highly overlapping set of target genes, including regulators of neural stem cell and neuron fate, and signalling pathways that regulate CNS development such as Notch and Hippo. Modulation of either Sd or Nerfin-1 activity causes medulla neurons to dedifferentiate to a stem cell-like state and this is mediated at least in part by Notch pathway deregulation. Intriguingly, orthologues of Sd and Nerfin-1 have also been implicated in control of neuronal cell fate decisions in both worms and mammals. Our data indicate that this transcription factor pair exhibits remarkable biochemical and functional conservation across metazoans. Overall design: DamID-seq on CNSs from wandering third instar Drosophila larvae expressing Dam control, Dam-Sd or Dam-Nerfin-1 transgenes driven by GMR31H08-Gal4 (two replicates each). ATACseq and RNAseq on FACS sorted wildtype Nerfin-GFP expressing neurons (3 replicates each).

细胞稳定维持自身细胞命运的能力，受特定转录调控因子的调控。本研究表明，转录因子Scalloped (Sd)与Nervous fingers-1 (Nerfin-1)可通过物理与功能互作，维持黑腹果蝇（Drosophila melanogaster）中枢神经系统（Central Nervous System, CNS）内髓质神经元的细胞命运。
本研究利用靶向DamID（Targeted DamID）技术发现，Sd与Nerfin-1所结合的靶基因集合高度重叠，其中涵盖神经干细胞与神经元命运调控因子，以及调控中枢神经系统发育的信号通路，如Notch与Hippo信号通路。对Sd或Nerfin-1活性进行调控，会导致髓质神经元去分化为干细胞样状态，且该过程至少部分由Notch通路失调所介导。
值得注意的是，Sd与Nerfin-1的同源基因在蠕虫与哺乳动物中同样被证实参与神经元细胞命运决定的调控。本研究数据表明，这一对转录因子在后生动物界中展现出显著的生化与功能保守性。
实验设计概况：对由GMR31H08-Gal4驱动表达Dam对照、Dam-Sd或Dam-Nerfin-1转基因的游走三龄黑腹果蝇幼虫的中枢神经系统开展DamID-seq测序（每组设置2次生物学重复）；对经荧光激活细胞分选（Fluorescence-Activated Cell Sorting, FACS）获得的野生型表达Nerfin-GFP的神经元开展ATAC-seq与RNA-seq测序（每组设置3次生物学重复）。