Morpholino-mediated inhibition of the NAMPT-NAD⁺-SIRT2 pathway impedes early hematopoiesis in zebrafish embryos. (A,C) Quantification of EGFP⁺ hematopoietic cells in uninjected control and morpholino (MO)/plasmid injected Tg(-6.35drl:EGFP) zebrafish embryos at 24 hpf. Representative images and numbers of EGFP⁺ hematopoietic cells in the blood islands are shown. Data show mean ± SD (n = 5). *P < .05. Scale bars: 50 μm. (B,D) mRNA expression levels of the indicated genes in control and MO/plasmid injected zebrafish embryos at 24 hpf were assessed using quantitative RT-PCR. Target gene/actb1 mRNA expression ratios are shown. Data show mean ± SD from 3 independent experiments, each in triplicate. *P < .05. (E) Schematic for the NAMPT/SIRT2-mediated lysine deacetylation of the LMO2 transcription factor that is essential for the interaction of LMO2 with LDB1 and formation of the TAL1 complex. This activates the oncogenic transcriptional program and promotes T-cell leukemia development or induces blood cell formation.