CHD7 and Runx1 interaction provides a braking mechanism for hematopoietic differentiation [ATAC-seq]. CHD7 and Runx1 interaction provides a braking mechanism for hematopoietic differentiation [ATAC-seq]

Hematopoietic stem and progenitor cell (HSPC) formation and lineage differentiation involve gene expression programs orchestrated by transcription factors and epigenetic regulators. Knockdown of the chromatin remodeler chromodomain-helicase-DNA-binding protein 7 (CHD7) expanded phenotypic HSPCs, erythroid, and myeloid lineages in zebrafish and mouse embryos. CHD7 acts to suppress hematopoietic differentiation in a cell autonomous manner in the embryo and adult. CHD7 chromatin immunoprecipitation in human CD34+ and mouse HSPCs revealed enrichment of binding motifs for hematopoietic transcription factors including Runx1 and GATA factors, and decreased Runx1 occupancy correlated with loss of CHD7 occupancy. CHD7 physically interacts with Runx1 and suppresses Runx1-induced expansion of HSPCs during development, providing both physical and genetic evidence for the Runx1-CHD7 interaction. CHD7 modulates Runx1 activity to provide proper timing and function of HSPCs as they emerge during hematopoietic development or mature in adults, representing a distinct and evolutionarily conserved control mechanism to ensure accurate hematopoietic lineage differentiation. Overall design: Effects of CHD7 knockout on chromatin accessibility in G1ER cells.

造血干祖细胞（hematopoietic stem and progenitor cell, HSPC）的形成与谱系分化，依赖由转录因子与表观遗传调控因子编排的基因表达程序。敲低染色质重塑因子染色质域解旋酶DNA结合蛋白7（chromodomain-helicase-DNA-binding protein 7, CHD7），可在斑马鱼与小鼠胚胎中扩增表型性造血干祖细胞、红系及髓系细胞谱系。CHD7在胚胎与成体个体中，均以细胞自主方式抑制造血分化。对人CD34+细胞与小鼠造血干祖细胞开展CHD7染色质免疫沉淀（chromatin immunoprecipitation）实验后发现，包括Runx1与GATA转录因子家族（GATA factors）在内的造血转录因子结合基序显著富集；且Runx1的染色质结合占有率降低，与CHD7结合位点的丢失呈显著相关。CHD7可与Runx1发生物理相互作用，并在发育过程中抑制Runx1介导的造血干祖细胞扩增，为二者的相互作用提供了物理与遗传学证据。CHD7通过调控Runx1的活性，在造血发育阶段造血干祖细胞产生或成体阶段造血干祖细胞成熟过程中，为其提供精准的时序调控与功能维持，这代表了一种独特且进化保守的调控机制，以保障造血谱系分化的精确性。本研究整体实验设计为：探究CHD7敲除对G1ER细胞染色质可及性的影响。