Investigating the impact of epigenetic heterogeneity on hematopoiesis hematopoietic stem cells (hscs) generate all blood and immune cell types of the body, and proper control of their self-renewal and…

Investigating the impact of epigenetic heterogeneity on hematopoiesis hematopoietic stem cells (hscs) generate all blood and immune cell types of the body, and proper control of their self-renewal and differentiation is essential for human health.1,2 since the work of till and mcculloch, heterogeneity has been recognized to be a cardinal feature of HSC biology. Clonally related cells can differ in their lineage decisions and showed preference towards certain cell fates, even in identical environments.1-6 researchers termed these skewed decisions as "lineage bias". Epigenetic mechanisms, such as post- translational histone modifications (`histone marks'), are postulated to be a possible factor contributing to individual hscs heterogeneity and its lineage bias. For example, recent studies suggest that levels of repressive histone marks at silent gene loci can vary considerably from cell-to-cell and repressive histone marks such as H3K27ME3 can be stably inherited through generations. Since lineage-specifying genes involved in hematopoiesis are typically held in a repressive state until differentiation, i hypothesize that individual hscs show substantial epigenetic state heterogeneity at lineage-specifying gene loci and that this epigenetic heterogeneity creates stable, heritable lineage biases in these cells. To test this hypothesis, i will determine the extent of epigenetic heterogeneity present in hscs, as well as whether IT impacts lineage potential for hscs. Both of these questions remain unclear due to the lack of methods that can measure epigenetic states consisting of an array of histone marks and their dynamics within single cells. Recently, the vaughan and kueh group developed a methodology termed single-cell evaluation of post translational epigenetic encoding (sceptre), which uses super resolution microscopy to resolve and quantify multiple histone marks at specific gene loci of interest simultaneously. I will use sceptre to investigate the extent of epigenetic heterogeneity present in hscs and its descendants (AIM1) first. Then, i will interrogate the heritability and impact of repressive epigenetic states by coupling sceptre with live-cell tracking (AIM2). If successful, the project will provide an exciting first look into epigenetic regulation in hscs at the single-cell level, paving the way for downstream studies to reveal fundamental aspects of their control and action.