Single-cell transcriptomic analysis of sibling progenitors with differential Notch activity

点击翻译按钮获取中文摘要

PROJECT SUMMARY It has been observed across species that embryonic radial glia neural progenitors undergo asymmetric cell division (ACD) to generate daughter cells with different Notch activity. The Notchhi daughter undergoes self- renewal, whereas the Notchlo daughter embarks on differentiation. Being able to molecularly define such different states will significantly advance our understanding of how self-renewal and differentiation are regulated. Although the relative Notch activity levels between embryonic daughters are correlated with their self- renewing vs. differentiation potential, the absolute Notch activity is heterogeneous across the progenitor population. This makes it impossible to simply sort single-cell RNA-seq (scRNA-seq) data based on the expression levels of Notch effectors (e.g. hes/her transcript levels). It is therefore important to track the lineage relationships among progenitors precisely at the level of sibling cells in scRNA-seq experiments. This exploratory R21 application, motivated by an important biological problem, aims to establish high resolution sib lineage-tracing and combine it with scRNA-seq. This represents a technological breakthrough that will enable comparison of gene expression profiles between sibling cells. Expected outcomes and impact: If successful, this project will establish a new and broadly applicable method in which sib cell states can be compared at the transcriptomic level both in vivo and in vitro. By applying this method to embryonic radial glia progenitors that are undergoing asymmetric cell division during active neurogenesis, we expect to uncover evolutionarily conserved core genes and pathways distinguishing Notchhi and Notchlo sib states that are shared across sib-lineages. Since Notchhi and Notchlo sib states are associated with self-renewal and differentiation respectively in embryonic progenitors, we expect to gain a glimpse into whether and how self-renewal and differentiation as distinct cellular states can be depicted at the transcriptomic level that are uncoupled from specific lineage outcomes. We will make this novel dataset with precise clonal tracking widely available to the broad research community. This project will lay foundation for a future R01, which aims to dissect the function of signature genes and pathways that define Notchhi vs. Notchlo cell states. In the long run, new basic knowledge about the underlying genetic programs will aid in developing new therapeutic ideas. The high risk and high reward nature of the proposed work makes this application well suited for the R21 mechanism.