Browsing by Subject "Genetic diseases"

Now showing 1 - 6 of 6
  • Thumbnail Image
    Item
    Developmental vascular malformations in EPAS1 gain-of-function syndrome
    (American Society for Clinical Investigation, 2021-03-08) Rosenblum, Jared S.; Wang, Herui; Dmitriev, Pauline M.; Cappadona, Anthony J.; Mastorakos, Panagiotis; Xu, Chen; Jha, Abhishek; Edwards, Nancy; Donahue, Danielle R.; Munasinghe, Jeeva; Nazari, Matthew A.; Knutsen, Russell H.; Rosenblum, Bruce R.; Smirniotopoulos, James G.; Pappo, Alberto; Spetzler, Robert F.; Vortmeyer, Alexander; Gilbert, Mark R.; McGavern, Dorian B.; Chew, Emily; Kozel, Beth A.; Heiss, John D.; Zhuang, Zhengping; Pacak, Karel; Pathology and Laboratory Medicine, School of Medicine
    Mutations in EPAS1, encoding hypoxia-inducible factor-2α (HIF-2α), were previously identified in a syndrome of multiple paragangliomas, somatostatinoma, and polycythemia. HIF-2α, when dimerized with HIF-1β, acts as an angiogenic transcription factor. Patients referred to the NIH for new, recurrent, and/or metastatic paraganglioma or pheochromocytoma were confirmed for EPAS1 gain-of-function mutation; imaging was evaluated for vascular malformations. We evaluated the Epas1A529V transgenic syndrome mouse model, corresponding to the mutation initially detected in the patients (EPAS1A530V), for vascular malformations via intravital 2-photon microscopy of meningeal vessels, terminal vascular perfusion with Microfil silicate polymer and subsequent intact ex vivo 14T MRI and micro-CT, and histologic sectioning and staining of the brain and identified pathologies. Further, we evaluated retinas from corresponding developmental time points (P7, P14, and P21) and the adult dura via immunofluorescent labeling of vessels and confocal imaging. We identified a spectrum of vascular malformations in all 9 syndromic patients and in all our tested mutant mice. Patient vessels had higher variant allele frequency than adjacent normal tissue. Veins of the murine retina and intracranial dura failed to regress normally at the expected developmental time points. These findings add vascular malformation as a new clinical feature of EPAS1 gain-of-function syndrome.
  • Thumbnail Image
    Item
    Down syndrome mouse models have an abnormal enteric nervous system
    (American Society for Clinical Investigation, 2019-04-18) Schill, Ellen M.; Wright, Christina M.; Jamil, Alisha; LaCombe, Jonathan M.; Roper, Randall J.; Heuckeroth, Robert O.; Biology, School of Science
    Children with trisomy 21 (Down syndrome [DS]) have a 130-fold increased incidence of Hirschsprung Disease (HSCR), a developmental defect where the enteric nervous system (ENS) is missing from distal bowel (i.e., distal bowel is aganglionic). Treatment for HSCR is surgical resection of aganglionic bowel, but many children have bowel problems after surgery. Post-surgical problems like enterocolitis and soiling are especially common in children with DS. To determine how trisomy 21 affects ENS development, we evaluated the ENS in two DS mouse models, Ts65Dn and Tc1. These mice are trisomic for many chromosome 21 homologous genes, including Dscam and Dyrk1a, which are hypothesized to contribute to HSCR risk. Ts65Dn and Tc1 mice have normal ENS precursor migration at E12.5 and almost normal myenteric plexus structure as adults. However, Ts65Dn and Tc1 mice have markedly reduced submucosal plexus neuron density throughout the bowel. Surprisingly, the submucosal neuron defect in Ts65Dn mice is not due to excess Dscam or Dyrk1a, since normalizing copy number for these genes does not rescue the defect. These findings suggest the possibility that the high frequency of bowel problems in children with DS and HSCR may occur because of additional unrecognized problems with ENS structure.
  • Thumbnail Image
    Item
    Early ascertainment of genetic diagnoses clarifies impact on medium-term survival following neonatal congenital heart surgery
    (American Society for Clinical Investigation, 2024-07-30) Landis, Benjamin J.; Helm, Benjamin M.; Durbin, Matthew D.; Helvaty, Lindsey R.; Herrmann, Jeremy L.; Johansen, Michael; Geddes, Gabrielle C.; Ware, Stephanie M.; Pediatrics, School of Medicine
  • Thumbnail Image
    Item
    Genetically programmed alternative splicing of NEMO mediates an autoinflammatory disease phenotype
    (The American Society for Clinical Investigation, 2022) Lee, Younglang; Wessel, Alex W.; Xu, Jiazhi; Reinke, Julia G.; Lee, Eries; Kim, Somin M.; Hsu, Amy P.; Zilberman-Rudenko, Jevgenia; Cao, Sha; Enos, Clinton; Brooks, Stephen R.; Deng, Zuoming; Lin, Bin; de Jesus, Adriana A.; Hupalo, Daniel N.; Piotto, Daniela G.P.; Terreri, Maria T.; Dimitriades, Victoria R.; Dalgard, Clifton L.; Holland, Steven M.; Goldbach-Mansky, Raphaela; Siegel, Richard M.; Hanson, Eric P.; Pediatrics, School of Medicine
    Host defense and inflammation are regulated by the NF-κB essential modulator (NEMO), a scaffolding protein with a broad immune cell and tissue expression profile. Hypomorphic mutations in inhibitor of NF-κB kinase regulatory subunit gamma (IKBKG) encoding NEMO typically present with immunodeficiency. Here, we characterized a pediatric autoinflammatory syndrome in 3 unrelated male patients with distinct X-linked IKBKG germline mutations that led to overexpression of a NEMO protein isoform lacking the domain encoded by exon 5 (NEMO-Δex5). This isoform failed to associate with TANK binding kinase 1 (TBK1), and dermal fibroblasts from affected patients activated NF-κB in response to TNF but not TLR3 or RIG-I-like receptor (RLR) stimulation when isoform levels were high. By contrast, T cells, monocytes, and macrophages that expressed NEMO-Δex5 exhibited increased NF-κB activation and IFN production, and blood cells from these patients expressed a strong IFN and NF-κB transcriptional signature. Immune cells and TNF-stimulated dermal fibroblasts upregulated the inducible IKK protein (IKKi) that was stabilized by NEMO-Δex5, promoting type I IFN induction and antiviral responses. These data revealed how IKBKG mutations that lead to alternative splicing of skipping exon 5 cause a clinical phenotype we have named NEMO deleted exon 5 autoinflammatory syndrome (NDAS), distinct from the immune deficiency syndrome resulting from loss-of-function IKBKG mutations.
  • Thumbnail Image
    Item
    Mice expressing KrasG12D in hematopoietic multipotent progenitor cells develop neonatal myeloid leukemia
    (American Society for Clinical Investigation, 2017-10-02) Tarnawsky, Stefan P.; Kobayashi, Michihiro; Chan, Rebecca J.; Yoder, Mervin C.; Biochemistry and Molecular Biology, School of Medicine
    Juvenile myelomonocytic leukemia (JMML) is a pediatric myeloproliferative neoplasm that bears distinct characteristics associated with abnormal fetal development. JMML has been extensively modeled in mice expressing the oncogenic KrasG12D mutation. However, these models have struggled to recapitulate the defining features of JMML due to in utero lethality, nonhematopoietic expression, and the pervasive emergence of T cell acute lymphoblastic leukemia. Here, we have developed a model of JMML using mice that express KrasG12D in multipotent progenitor cells (Flt3Cre+ KrasG12D mice). These mice express KrasG12D in utero, are born at normal Mendelian ratios, develop hepatosplenomegaly, anemia, and thrombocytopenia, and succumb to a rapidly progressing and fully penetrant neonatal myeloid disease. Mutant mice have altered hematopoietic stem and progenitor cell populations in the BM and spleen that are hypersensitive to granulocyte macrophage-CSF due to hyperactive RAS/ERK signaling. Biased differentiation in these progenitors results in an expansion of neutrophils and DCs and a concomitant decrease in T lymphocytes. Flt3Cre+ KrasG12D fetal liver hematopoietic progenitors give rise to a myeloid disease upon transplantation. In summary, we describe a KrasG12D mouse model that reproducibly develops JMML-like disease. This model will prove useful for preclinical drug studies and for elucidating the developmental origins of pediatric neoplasms.
  • Thumbnail Image
    Item
    Spatial transcriptomics implicates impaired BMP signaling in NF1 fracture pseudarthrosis in murine and patient tissues
    (American Society for Clinical Investigation, 2024-07-11) Rios, Jonathan J.; Juan, Conan; Shelton, John M.; Paria, Nandina; Oxendine, Ila; Wassell, Meghan; Kidane, Yared H.; Cornelia, Reuel; Jeffery, Elise C.; Podeszwa, David A.; Conway, Simon J.; Wise, Carol A.; Tower, Robert J.; Pediatrics, School of Medicine
    The neurofibromatosis type 1 (NF1) RASopathy is associated with persistent fibrotic nonunions (pseudarthrosis) in human and mouse skeletal tissue. Here, we performed spatial transcriptomics to define the molecular signatures occurring during normal endochondral healing following fracture in mice. Within the control fracture callus, we observed spatially restricted activation of morphogenetic pathways, such as TGF-β, WNT, and BMP. To investigate the molecular mechanisms contributing to Nf1-deficient delayed fracture healing, we performed spatial transcriptomic analysis on a Postn-cre;Nf1fl/- (Nf1Postn) fracture callus. Transcriptional analyses, subsequently confirmed through phospho-SMAD1/5/8 immunohistochemistry, demonstrated a lack of BMP pathway induction in Nf1Postn mice. To gain further insight into the human condition, we performed spatial transcriptomic analysis of fracture pseudarthrosis tissue from a patient with NF1. Analyses detected increased MAPK signaling at the fibrocartilaginous-osseus junction. Similar to that in the Nf1Postn fracture, BMP pathway activation was absent within the pseudarthrosis tissue. Our results demonstrate the feasibility of delineating the molecular and tissue-specific heterogeneity inherent in complex regenerative processes, such as fracture healing, and reconstructing phase transitions representing endochondral bone formation in vivo. Furthermore, our results provide in situ molecular evidence of impaired BMP signaling underlying NF1 pseudarthrosis, potentially informing the clinical relevance of off-label BMP2 as a therapeutic intervention.