Interactions of signalling pathways in genome maintenance during neurogenesis

这个项目的目的是了解染色体不稳定性是如何在发育中的大脑中产生的。神经祖细胞和神经元是镶嵌现象研究的热点，镶嵌现象与神经元特化以及多种神经发育障碍和衰老疾病有关。然而，如何在不同的发育谱系中监测基因组的稳定性——包括在大脑中——在很大程度上仍然是未知的。在具体的研究结果中，我们发现大脑模式信号Wnt和FGF形成了一种拉锯战，在神经发生过程中调节染色体分离的保真度。在这里，我们将采用人类和小鼠神经干细胞模型来表征FGF和Wnt信号通路之间的功能相互作用，并确定它们对大脑中众所周知的高水平基因组嵌合体的贡献。首先，我们将通过最先进的单细胞基因组和转录组测序，描述FGF和Wnt在体外人类神经元发育过程中对结构和数量染色体维持的贡献。其次，我们将定义这种新型信号拉锯战在小鼠大脑发育过程中控制神经祖细胞和神经元染色体稳定性中的时空作用。模式信号作为染色体稳定性来源的兼职作用的发现构成了一个突破性的发展新原理。我们的工作将为预防目前阻碍其治疗应用的干细胞基因组异常提供新的见解，并理解为什么基因组嵌合现象在大脑中普遍存在，而在其他器官中却没有。最后，我们的工作可以为研究与染色体不稳定性相关的神经发育障碍开辟新的途径。

The aim of this project is to understand how chromosomal instability arises in the developing brain. Neural progenitors and neurons are hotspots for mosaicism, which has been associated with neuronal specialization, as well as several neuro-developmental disorders and aging diseases. However, how genome stability is monitored across different developmental lineages - including in the brain - remains largely uncharacterized. In proposal specific results, we identified that the brain patterning signals Wnt and FGF form a tug-of-war that regulates chromosome segregation fidelity during neurogenesis. Here, we will employ human and mouse neural stem cell models to characterize the functional interactions between FGF and Wnt signalling pathways, and to determine their contribution to the notoriously high levels of genomic mosaicism in the brain. First, we will characterize the contribution of FGF and Wnt to structural and numerical chromosome maintenance during in vitro human neuronal specification, including by state-of-the-art single cell genome and transcriptome sequencing. Second, we will define the spatio-temporal roles of this novel signalling tug-of-war in the control of chromosome stability in neural progenitors and neurons during in vivo mouse brain development. The discovery of a moonlighting role of patterning signals as sources of chromosome (in)stability constitutes a ground-breaking new principle in development. Our work will provide novel insights relevant to prevent genomic abnormalities in stem cells that currently preclude their therapeutic application, and to understand why genomic mosaicism is prevalent in the brain, but no in other organs. Finally, our work could open new avenues to investigate neuro-developmental disorders associated with chromosomal instability.