NF-κB derived from endothelial cells mediates the TLR regulation of HSPC emergence. (A) Top panel, Endothelial dnIκBaa-GFP⁺ signals. Red arrowheads mark GFP signal in the endothelial cells. Bottom panels, The decreased expression of p-IKBa in dnikbaa⁻ and dnikbaa⁺ embryos. (B-C) Overexpression of dnikbaa in endothelial cells led to decreased expression of runx1. (D) Decreased expression of runx1 at 36 hpf in tlr4bb or myd88 morphants was rescued by coinjection of ikbaa MO. (E) The decreased population of cmyb⁺kdrl⁺ cells in Tg(cmyb:GFP/kdrl:mCherry) embryos injected with tlr4bb or myd88 MO, was rescued by coinjection with ikbaa MO. White arrowheads mark cmyb⁺kdrl⁺ cells in the AGM region at 36 hpf. (F) Quantification of cmyb⁺kdrl⁺ cells. Data are presented as mean ± SEM of 3 independent samples. Each sample was composed of at least 5 embryos. *P < .05, **P < .01. (G) Decreased expression of runx1 at 36 hpf in tlr4bb or myd88 morphants was rescued by the overexpression of il1b from 20 hpf.