Investigating the role of YAP1 in blood cell specification - PROJECT SUMMARY/ABSTRACT Birth defects are the primary cause of infant mortality in the United States, affecting twenty percent of total infant deaths. Thus, comprehensive insights into the intricate regulation of human development are essential to devise innovative therapies and prevention strategies to combat birth defects. During embryonic development, a complex interplay of signaling pathways, effector molecules, and chromatin regulators work together to regulate lineage-specific gene expression during cell-fate transitions. Gastrulation is required for normal development and leads to the specification of the three germinal layers; mesoderm, ectoderm, and endoderm. While rare, disruptions or errors during gastrulation can lead to improper formation of tissues and organs in the developing fetus. One of the first cell types specified during gastrulation is the blood cell precursors called hemangioblasts, which derive from the primitive streak (PS). Defects in hemangioblast formation cause disruptions in the normal development of blood cells, leading to various vascular and hematological disorders. Extensive literature has shown the cellular mechanisms that determine primitive hematopoietic cells; however, how these precursor cells are specified during the early stages of PS is understudied. The scientific premise of this proposal is based upon the repressive transcriptional role of the Hippo signaling effector, Yes-associated Protein 1 (YAP1), on hemangioblast formation. YAP1 is a known transcriptional effector involved in the Hippo signaling pathway that has been widely studied for its transcriptional activity in regulating cell growth and proliferation. Our preliminary data suggest a novel regulatory mechanism of YAP1 mediating the recruitment of Enhancer of zeste homolog 2 (EZH2) to blood lineage genes during hemangioblast formation. Based on these observations, our central hypothesis is that “YAP1-mediated recruitment of EZH2 on blood lineage genes restrict hemangioblast cell specification.” We will test our central hypothesis by conducting experiments organized under the following two specific aims: Aim 1: To investigate the role of YAP1 in hemangioblast formation and primitive streak patterning at single-cell resolution in vivo and Aim 2. Molecular analysis of YAP1-mediated regulation of blood lineage genes in hESCs. The proposed studies are significant as they highlight the essential role of YAP1 and EZH2 coordination during blood development. The proposal aims to enhance both technical (single-cell omics and next-generation sequencing) and conceptual skills in signaling and chromatin dynamics during early development; this will help promote my Ph.D. training and overall career.
