Project description:The high-mobility-group (HMG) proteins are the most abundant non-histone chromatin-associated proteins. Here we deciphered the role of the high mobility group AT-hook protein 2 (HMGA2) during lung development by analyzing the lung of Hmga2 deficient mice (Hmga2-/-).We found that Hmga2 is expressed in the mouse embryonic lung at the distal airways. Analysis of Hmga2-/- mice showed that Hmga2 is required for proper cell proliferation and distal epithelium differentiation during embryonic lung development. Hmga2 knockout (KO) led to enhanced canonical WNT signaling due to an increased expression of secreted WNT glycoproteins Wnt2b, Wnt7b and Wnt11 as well as a reduction of the WNT signaling antagonizing proteins GATA6 (GATA binding protein 6) and FZD2 (frizzled homolog 2). Comparison of Hmga2-/- with Hmga2+/+ mice by Affymetrix microarray-based expression analysis of embryonic lung revealed an increased expression of genes whose products participate in cell cycle and canonical Wnt signaling. Affymetrix microarray transcriptome analysis of Hmga2-/- and Hmga2+/+ embryonic lung (E18.5) was performed and analyzed
Project description:The high-mobility-group (HMG) proteins are the most abundant non-histone chromatin-associated proteins. Here we deciphered the role of the high mobility group AT-hook protein 2 (HMGA2) during lung development by analyzing the lung of Hmga2 deficient mice (Hmga2-/-).We found that Hmga2 is expressed in the mouse embryonic lung at the distal airways. Analysis of Hmga2-/- mice showed that Hmga2 is required for proper cell proliferation and distal epithelium differentiation during embryonic lung development. Hmga2 knockout (KO) led to enhanced canonical WNT signaling due to an increased expression of secreted WNT glycoproteins Wnt2b, Wnt7b and Wnt11 as well as a reduction of the WNT signaling antagonizing proteins GATA6 (GATA binding protein 6) and FZD2 (frizzled homolog 2). Comparison of Hmga2-/- with Hmga2+/+ mice by Affymetrix microarray-based expression analysis of embryonic lung revealed an increased expression of genes whose products participate in cell cycle and canonical Wnt signaling.
Project description:Epithelial organs including the lung are known to possess regenerative abilities through activation of endogenous stem cell populations but the molecular pathways regulating stem cell expansion and regeneration are not well understood. Here we show that Gata6 regulates the temporal appearance and number of bronchioalveolar stem cells (BASCs) in the lung leading to the precocious appearance of BASCs and concurrent loss in epithelial differentiation in Gata6 null lung epithelium. This expansion of BASCs is the result of a dramatic increase in canonical Wnt signaling in lung epithelium upon loss of Gata6. Expression of the non-canonical Wnt receptor Fzd2 is down-regulated in Gata6 mutants and increased Fzd2 or decreased β-catenin expression rescues, in part, the lung epithelial defects in Gata6 mutants. During lung epithelial regeneration, we show that canonical Wnt signaling is activated in the niche containing BASCs and forced activation of Wnt signaling leads to a dramatic increase in BASC numbers. Moreover, Gata6 is required for proper lung epithelial regeneration and postnatal loss of Gata6 leads to increased BASC expansion and decreased differentiation. Together, these data demonstrate that Gata6 regulated Wnt signaling controls the balance between stem/progenitor expansion and epithelial differentiation required for both lung development and regeneration. Experiment Overall Design: 3 replicates of each condition-wild-type and GATA6 null tissue. 6 total samples.
Project description:Epithelial organs including the lung are known to possess regenerative abilities through activation of endogenous stem cell populations but the molecular pathways regulating stem cell expansion and regeneration are not well understood. Here we show that Gata6 regulates the temporal appearance and number of bronchioalveolar stem cells (BASCs) in the lung leading to the precocious appearance of BASCs and concurrent loss in epithelial differentiation in Gata6 null lung epithelium. This expansion of BASCs is the result of a dramatic increase in canonical Wnt signaling in lung epithelium upon loss of Gata6. Expression of the non-canonical Wnt receptor Fzd2 is down-regulated in Gata6 mutants and increased Fzd2 or decreased β-catenin expression rescues, in part, the lung epithelial defects in Gata6 mutants. During lung epithelial regeneration, we show that canonical Wnt signaling is activated in the niche containing BASCs and forced activation of Wnt signaling leads to a dramatic increase in BASC numbers. Moreover, Gata6 is required for proper lung epithelial regeneration and postnatal loss of Gata6 leads to increased BASC expansion and decreased differentiation. Together, these data demonstrate that Gata6 regulated Wnt signaling controls the balance between stem/progenitor expansion and epithelial differentiation required for both lung development and regeneration. Keywords: gene targets in knockout mouse model
Project description:In mammals, retinal damage is followed by Müller glia cell activation and proliferation. While retinal gliosis persists in adult mammals after an insult or disease, some vertebrates, including zebrafish, have the capacity to regenerate. We believe we are the first group to show that gliosis is a fibrotic-like process in mammals’ eyes caused by differential activation of canonical and non-canonical TGFβ signaling pathways.
Project description:Canonical Wnt signaling plays critical roles in development and tissue renewal by regulating β-catenin target genes. Recent evidence showed that β-catenin-independent Wnt signaling is also required for faithful execution of mitosis. This mitotic Wnt signaling functions through Wnt-dependent stabilization of proteins (Wnt/STOP), as well as through components of the LRP6 signalosome. However, the targets and specific functions of mitotic Wnt signaling still remain uncharacterized. Using phosphoproteomics, we identified that Wnt signaling regulates the microtubule depolymerase KIF2A during mitosis. We found that Dishevelled recruits KIF2A via its N-terminal and motor domains, which is further promoted upon LRP6 signalosome formation during mitosis. We show that Wnt signaling modulates KIF2A interaction with PLK1, which is critical for KIF2A localization and the assembly of a bipolar mitotic spindle. Accordingly, Wnt signaling promotes chromosome congression during metaphase by monitoring KIF2A protein levels at the spindle poles both in somatic cells and in pluripotent stem cells. Our findings highlight a novel function of Wnt signaling during cell division, which could have important implications for genome maintenance, notably in stem cells.
Project description:Alveologenesis is the culmination of lung development and involves the correct temporal and spatial signals to generate the delicate gas exchange interface. Using a novel Wnt signaling reporter system, we have identified a Wnt-responsive alveolar epithelial sublineage arising during alveologenesis called the axin2+ alveolar type 2 cell or AT2Aaxin2. The number of AT2Aaxin2 sublineage cells increases substantially during late lung development, revealing a wave of Wnt signaling during alveologenesis. Transcriptome analysis, in vivo clonal analysis, and ex vivo lung organoid assays reveal that AT2sAaxin2s promote enhanced AT2 cellalveolar growth during generation of the alveolus compared to the overall AT2 population. Activating Wnt signaling in the AT2 lineage results in expansion of the AT2axin2 sublineageAT2s whereas inhibition of Wnt signaling inhibits AT2 cell development and shunts alveolar epithelial development towards the AT1 cell lineage. These findings reveal a novel epithelial sublineage that coordinates Wnt-dependent alveolar growthAT2 expansion required for lung alveologenesis
Project description:SILAC based protein correlation profiling using size exclusion of protein complexes derived from Mus musculus tissues (Heart, Liver, Lung, Kidney, Skeletal Muscle, Thymus)