Project description:The intestinal epithelium is a paradigm of adult tissue in constant regeneration that is supported by intestinal stem cells (ISCs). The mechanisms regulating ISC homeostasis after injury are poorly understood. We previously demonstrated that IκBa, not only controls NF-κB activation, but also exerts nuclear functions as cytokine sensor in a subset of PRC2-regulated genes. We now uncover nuclear phosphorylated IκBa (P-IκBa) in the ISC compartment where it binds highly histone methylated genomic regions. Mice deficient for IκBa show aberrant distribution of H3K27me3 mark, and altered intestinal differentiation with persistence of a fetal-like ISC signature. In vitro, IκBa deficient intestinal cells produced morphologically aberrant organoids carrying a PRC2, Notch and IFN-dependent fetal-like transcriptional signature. Induction of the fetal-like phenotype by DSS treatment is associated with loss of nuclear P-IκBa in the damaged colonic epithelium and it subsequent accumulation in early CD44 positive regenerating areas. Importantly, IκBa deficient animals showed higher resistance to damage, likely due to persistent fetal-like phenotype. These results point out intestinal IκBa as chromatin sensor of inflammation in the ISC compartment.
Project description:The intestinal epithelium is a paradigm of adult tissue in constant regeneration that is supported by intestinal stem cells (ISCs). The mechanisms regulating ISC homeostasis after injury are poorly understood. We previously demonstrated that IκBa, not only controls NF-κB activation, but also exerts nuclear functions as cytokine sensor in a subset of PRC2-regulated genes. We now uncover nuclear phosphorylated IκBa (P-IκBa) in the ISC compartment where it binds highly histone methylated genomic regions. Mice deficient for IκBa show aberrant distribution of H3K27me3 mark, and altered intestinal differentiation with persistence of a fetal-like ISC signature. In vitro, IκBa deficient intestinal cells produced morphologically aberrant organoids carrying a PRC2, Notch and IFN-dependent fetal-like transcriptional signature. Induction of the fetal-like phenotype by DSS treatment is associated with loss of nuclear P-IκBa in the damaged colonic epithelium and it subsequent accumulation in early CD44 positive regenerating areas. Importantly, IκBa deficient animals showed higher resistance to damage, likely due to persistent fetal-like phenotype. These results point out intestinal IκBa as chromatin sensor of inflammation in the ISC compartment.
Project description:The intestinal epithelium is a paradigm of adult tissue in constant regeneration that is supported by intestinal stem cells (ISCs). The mechanisms regulating ISC homeostasis after injury are poorly understood. We previously demonstrated that IκBa, not only controls NF-κB activation, but also exerts nuclear functions as cytokine sensor in a subset of PRC2-regulated genes. We now uncover nuclear phosphorylated IκBa (P-IκBa) in the ISC compartment where it binds highly histone methylated genomic regions. Mice deficient for IκBa show aberrant distribution of H3K27me3 mark, and altered intestinal differentiation with persistence of a fetal-like ISC signature. In vitro, IκBa deficient intestinal cells produced morphologically aberrant organoids carrying a PRC2, Notch and IFN-dependent fetal-like transcriptional signature. Induction of the fetal-like phenotype by DSS treatment is associated with loss of nuclear P-IκBa in the damaged colonic epithelium and it subsequent accumulation in early CD44 positive regenerating areas. Importantly, IκBa deficient animals showed higher resistance to damage, likely due to persistent fetal-like phenotype. These results point out intestinal IκBa as chromatin sensor of inflammation in the ISC compartment.
Project description:The intestinal epithelium is a paradigm of adult tissue in constant regeneration that is supported by intestinal stem cells (ISCs). The mechanisms regulating ISC homeostasis after injury are poorly understood. We previously demonstrated that IκBα, the main regulator of NF-κB, exerts alternative nuclear functions as cytokine sensor in a subset of PRC2-regulated genes. Here, we show that nuclear IκBα is present in the ISC compartment. Mice deficient for IκBα show altered intestinal cell differentiation with persistence of a fetal-like ISC phenotype, associated with aberrant PRC2 activity at specific loci. Moreover, IκBα-deficient intestinal cells produce morphologically aberrant organoids carrying a PRC2-dependent fetal-like transcriptional signature. DSS treatment, which induces acute damage in the colonic epithelium of mice, results in a temporary loss of nuclear P-IκBα and its subsequent accumulation in early CD44-positive regenerating areas. Importantly, IκBα-deficient mice show higher resistance to damage, likely due to the persistent fetal-like ISC phenotype. These results highlight intestinal IκBα as a chromatin sensor of inflammation in the ISC compartment.
Project description:Classical NF-κB activity can be inhibited by overexpression of the IκBα super repressor (SR). To determine the role of NF-κB in rhabdomyosarcoma cells, we overexpressed the IκBα SR in RH30 rhabdomyosarcoma cells. IκBα SR was overexpressed in RH30 cells. RH30 vector cells were used as control group.
Project description:Hematopoietic Stem Cells (HSCs) originate from the E11.5 aorta-gonads-and mesonephros (AGM) region during development before they migrate to the foetal liver for proliferation and maturation, and finally seed the bone marrow around birth, their final site of residence. In the AGM, HSCs reside within Intra-aortic hematopoietic clusters (IAHC) along with hematopoietic progenitors (HPC). Molecular pathways that determine HSC fate instead of HPCs are still unknown, although inflammatory signalling has been implicated in the development of all blood cells, including NF-κB. Here, we describe a dormant phenotype of LT-HSCs in the IκBα KO. Although IκBα is critical for retaining inactive NF-κB complexes in the cytoplasm, it can regulate stem cell related genes by interacting with the PRC2 complex in the nucleus. Accordingly, we find decreased PRC2 dependent H3K27me3 accumulation at the promoters of PI3K and retinoic acid signalling molecules by cut and tag assay in AGM derived CD31+ cells, which includes HE/IAHC derived from IκBα KO embryos. Furthermore, this regulation of the retinoic acid signalling by IκBα is further confirmed by cut and tag assay for IκBα itself in CD31+ cells of the AGM and more specifically also in sorted LT-HSCs from the E14.5 foetal liver. Over-activation of the retinoic acid/PI3K levels in LT-HSCs of the IκBα KO is evident in their dormant molecular profile. Functionally, IκBα KO LT-HSCs are less proliferative and respond with delayed activation upon transplantation. Overall, we identify nuclear IκBα as an essential player specifically for HSC specification/proliferation from the onset of HSPC emergence in the AGM.