Smarca5 deletion impairs the genomic binding of hematopoietic TFs. (A) Motif scan results at sites with lost accessibility after smarca5 deletion. For each presented pair, the top one is the motif from JASPAR database; the bottom one is the scanned motif. (B) qPCR analysis showing the expression of ptena, bcl11ab, crtc3, chaf1b, nfe2l2a, and nfe2l1b in HSPCs from smarca5^zko1049a and their siblings. (C) The genome browser views showing the track of Smarca5 and Ncl occupancy in bcl11ab promoter with ATAC-seq peaks. The gray box indicates the change of ATAC-seq peaks after smarca5 deletion. The location of a predicted Spi1 binding site is marked by a black line. (D) Expression of cmyb in the CHT region in smarca5^zko1049a and their siblings at 3.5 dpf, with or without Bcl11ab overexpression from 2 dpf to 3 dpf by WISH. The quantification of WISH results is shown (right). Scale bars, 100 μm. (E) ChIP-qPCR analysis of H2A occupancy compared with immunoglobulin G (IgG) in the promoter of bcl11ab in smarca5^zko1049a and their siblings. (F) ChIP-qPCR analysis of H2A occupancy compared with IgG in the promoter of bcl11ab in ncl^m4 and their siblings. (G) A model shows that Smarca5-mediated chromatin accessibility programming is responsible for fetal HSPC development. The chromatin remodeler smarca5 plays an important role in regulating chromatin accessibility to facilitate the binding of hematopoietic TFs, such as Klf1 and Spi1. Moreover, Ncl is identified to collaborate with Smarca5 to facilitate efficient chromatin remodeling. Data are means ± SD (B,D-F). Asterisk presents statistical significance (*P < .05, **P < .01, ***P < .001; n.s., not significant). P values were calculated by a 2-tailed, unpaired Student t test.