ChIP-on-chip with anti-RBPj antibody from embryonic AGM E11.5. Mus musculus

Hematopoietic Stem Cells (HSC) are originated during embryonic development from endothelial-like cells located in the ventral side of the dorsal aorta around day E10-12 of murine development. This region is called AGM for Aorta/Gonad/Mesonephros refering to the tissues around the hemogenic aorta. Hematopoiesis depends on the Notch pathway and the identification of Notch-targets is important for the understanding of blood origin. Overall design: Hematopoietic Stem Cells (HSCs) specification occurs in the embryonic aorta and requires Notch activation, however which are the elements regulated by Notch that control this process are mainly unknown. Here, we took a genome-wide approach to identify putative direct Notch targets by precipitating the chromatin that binds to the Notch partner RBPj in the Aorta-Gonad-Mesonephros (AGM) tissue from E11.5 mouse embryos. This assay revealed 701 gene promoter regions as candidates to be regulated by Notch in the AGM. Chromatin was obtained from a pool of 40 dissected AGMs at E11.5. Chromatin immunoprecipitation (ChIP) was performed as previously described (Aguilera et al, PNAS 2004) with minor modifications. In brief, cross-linked chromatin was sonicated for 10 minutes, medium-power, 0.5-interval; with a Bioruptor (Diagenode) and precipitated with anti-RBPJ (Chu and Bresnick, 2004). After crosslinkage reversal, DNA was used as a template for PCR or for array hybridization. Mouse promoter chip on chip microarray SET (Agilent) was used to identify RBPj targets. It covers 70,000 best identified gene regions with a-5.5 kb to + 2.5 kb range, and has on average 25 probes per gene with an average probe to probe distance of 200 bp. The ChIP-on-chip was performed with dye swaps and one IgG control was brought along. Enrichment analysis was done by comparing the precipitation normalized dye swap signal with input control signal.