Fig. 7

Elevated expression of p53 and p21 in IL-27R-deficient HSPCs. a Scheme of experiment. b Lin⁻ HSPCs isolated from WD-fed Apoe^−/−Il27ra^+/− (n = 4) and Apoe^−/−Il27ra^−/− (n = 4) mice infused with PBS or Apoe^−/−Il27ra^+/− (n = 5) and Apoe^−/−Il27ra^−/− (n = 4) mice infused with Ang II for 4 weeks were lysed and subjected to western blotting with p21, p53, and β-actin antibody. Each lane corresponds to individual mouse. c Quantification of WB analysis for p21 and p53, normalized to β-actin. d Scheme of experiment. e WB on Lin⁻ HSPCs from naive Apoe^−/−Il27ra^+/− mice (n = 4) stimulated in vitro with Ang II, IL-27, or both for 24 h. f Quantification of WB analysis for p21. g Scheme of experiment. h Lin⁻ HSPCs from BM of Apoe^−/− (n = 4), Apoe^−/−Il27ra^−/− (n = 4), or Apoe^−/−Il27ra^−/−Trp53^d/d (n = 5) mice were sorted and plated in M3434 media under myeloid conditions with or without Ang II. GM colony formation was accessed on day 6. Data are mean ± SEM from two independent experiments. *p < 0.05, **p < 0.01, ***p < 0.005, unpaired Student’s t-test (two-tailed). i Scheme describing the role of IL-27R signaling in regulation of Ang II-induced myelopoiesis and AAA. Elevation of Ang II in AAA provides a stimulus for the activation of “stress” myelopoiesis via regulation of gene expression controlling proliferation and differentiation in IL-27R-sufficient LT-HSCs. Lack of IL-27R signaling renders Ang II-primed cells unable to overcome quiescence state and significantly reduces proliferation of progenitors and myeloid cell bone marrow output, therefore reducing cell accumulation in AAA lesions and AAA progression