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Zhong X, Peddada N, Wang J, Moresco JJ, Zhan X, Shelton JM, SoRelle JA, Keller K, Lazaro DR, Moresco EMY, Choi JH, Beutler B. OVOL2 sustains postnatal thymic epithelial cell identity. Nat Commun 2023; 14:7786. [PMID: 38012144 PMCID: PMC10682436 DOI: 10.1038/s41467-023-43456-z] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/13/2023] [Accepted: 11/09/2023] [Indexed: 11/29/2023] Open
Abstract
Distinct pathways and molecules may support embryonic versus postnatal thymic epithelial cell (TEC) development and maintenance. Here, we identify a mechanism by which TEC numbers and function are maintained postnatally. A viable missense allele (C120Y) of Ovol2, expressed ubiquitously or specifically in TECs, results in lymphopenia, in which T cell development is compromised by loss of medullary TECs and dysfunction of cortical TECs. We show that the epithelial identity of TECs is aberrantly subverted towards a mesenchymal state in OVOL2-deficient mice. We demonstrate that OVOL2 inhibits the epigenetic regulatory BRAF-HDAC complex, specifically disrupting RCOR1-LSD1 interaction. This causes inhibition of LSD1-mediated H3K4me2 demethylation, resulting in chromatin accessibility and transcriptional activation of epithelial genes. Thus, OVOL2 controls the epigenetic landscape of TECs to enforce TEC identity. The identification of a non-redundant postnatal mechanism for TEC maintenance offers an entry point to understanding thymic involution, which normally begins in early adulthood.
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Affiliation(s)
- Xue Zhong
- Center for the Genetics of Host Defense, University of Texas Southwestern Medical Center, Dallas, TX, 75390-8505, USA
| | - Nagesh Peddada
- Center for the Genetics of Host Defense, University of Texas Southwestern Medical Center, Dallas, TX, 75390-8505, USA
| | - Jianhui Wang
- Center for the Genetics of Host Defense, University of Texas Southwestern Medical Center, Dallas, TX, 75390-8505, USA
| | - James J Moresco
- Center for the Genetics of Host Defense, University of Texas Southwestern Medical Center, Dallas, TX, 75390-8505, USA
| | - Xiaowei Zhan
- Center for the Genetics of Host Defense, University of Texas Southwestern Medical Center, Dallas, TX, 75390-8505, USA
- Department of Population and Data Sciences, Quantitative Biomedical Research Center, University of Texas Southwestern Medical Center, Dallas, TX, 75390-8821, USA
| | - John M Shelton
- Intermal Medicine-Histopathology Core, University of Texas Southwestern Medical Center, Dallas, TX, 75390-8573, USA
| | - Jeffrey A SoRelle
- Department of Pathology, University of Texas Southwestern Medical Center, Dallas, TX, 75390-9072, USA
- Department of Pediatrics, University of Texas Southwestern Medical Center, Dallas, TX, 75390-9063, USA
| | - Katie Keller
- Center for the Genetics of Host Defense, University of Texas Southwestern Medical Center, Dallas, TX, 75390-8505, USA
| | - Danielle Renee Lazaro
- Center for the Genetics of Host Defense, University of Texas Southwestern Medical Center, Dallas, TX, 75390-8505, USA
| | - Eva Marie Y Moresco
- Center for the Genetics of Host Defense, University of Texas Southwestern Medical Center, Dallas, TX, 75390-8505, USA
| | - Jin Huk Choi
- Center for the Genetics of Host Defense, University of Texas Southwestern Medical Center, Dallas, TX, 75390-8505, USA.
| | - Bruce Beutler
- Center for the Genetics of Host Defense, University of Texas Southwestern Medical Center, Dallas, TX, 75390-8505, USA.
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Li Y, Zhu Q, Zhou S, Chen J, Du A, Qin C. Combined bulk RNA and single-cell RNA analyses reveal TXNL4A as a new biomarker for hepatocellular carcinoma. Front Oncol 2023; 13:1202732. [PMID: 37305572 PMCID: PMC10248245 DOI: 10.3389/fonc.2023.1202732] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/09/2023] [Accepted: 05/16/2023] [Indexed: 06/13/2023] Open
Abstract
Introduction Hepatocellular carcinoma (HCC) has a high mortality rate worldwide. The dysregulation of RNA splicing is a major event leading to the occurrence, progression, and drug resistance of cancer. Therefore, it is important to identify new biomarkers of HCC from the RNA splicing pathway. Methods We performed the differential expression and prognostic analyses of RNA splicing-related genes (RRGs) using The Cancer Genome Atlas-liver hepatocellular carcinoma (LIHC). The International Cancer Genome Consortium (ICGC)-LIHC dataset was used to construct and validate prognostic models, and the PubMed database was used to explore genes in the models to identify new markers. The screened genes were subjected to genomic analyses, including differential, prognostic, enrichment, and immunocorrelation analyses. Single-cell RNA (scRNA) data were used to further validate the immunogenetic relationship. Results Of 215 RRGs, we identified 75 differentially expressed prognosis-related genes, and a prognostic model incorporating thioredoxin like 4A (TXNL4A) was identified using least absolute shrinkage and selection operator regression analysis. ICGC-LIHC was used as a validation dataset to confirm the validity of the model. PubMed failed to retrieve HCC-related studies on TXNL4A. TXNL4A was highly expressed in most tumors and was associated with HCC survival. Chi-squared analyses indicated that TXNL4A expression positively correlated positively with the clinical features of HCC. Multivariate analyses revealed that high TXNL4A expression was an independent risk factor for HCC. Immunocorrelation and scRNA data analyses indicated that TXNL4A was correlated with CD8 T cell infiltration in HCC. Conclusion Therefore, we identified a prognostic and immune-related marker for HCC from the RNA splicing pathway.
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Affiliation(s)
- Yifan Li
- Department of Gastrointestinal Surgery, Huaihe Hospital of Henan University, Kaifeng, Henan, China
| | - Qiaozhen Zhu
- Infection and Immunity Institute and Translational Medical Center, Huaihe Hospital, Kaifeng, Henan, China
| | - Shuchang Zhou
- Department of Gastrointestinal Surgery, Huaihe Hospital of Henan University, Kaifeng, Henan, China
| | - Jiangtao Chen
- Department of Gastrointestinal Surgery, Huaihe Hospital of Henan University, Kaifeng, Henan, China
| | - Aoyu Du
- Department of Plastic Surgery, Huaihe Hospital of Henan University, Kaifeng, Henan, China
| | - Changjiang Qin
- Department of Gastrointestinal Surgery, Huaihe Hospital of Henan University, Kaifeng, Henan, China
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Yang H, Beutler B, Zhang D. Emerging roles of spliceosome in cancer and immunity. Protein Cell 2021; 13:559-579. [PMID: 34196950 PMCID: PMC9232692 DOI: 10.1007/s13238-021-00856-5] [Citation(s) in RCA: 32] [Impact Index Per Article: 10.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/31/2020] [Accepted: 05/08/2021] [Indexed: 12/19/2022] Open
Abstract
Precursor messenger RNA (pre-mRNA) splicing is catalyzed by an intricate ribonucleoprotein complex called the spliceosome. Although the spliceosome is considered to be general cell “housekeeping” machinery, mutations in core components of the spliceosome frequently correlate with cell- or tissue-specific phenotypes and diseases. In this review, we expound the links between spliceosome mutations, aberrant splicing, and human cancers. Remarkably, spliceosome-targeted therapies (STTs) have become efficient anti-cancer strategies for cancer patients with splicing defects. We also highlight the links between spliceosome and immune signaling. Recent studies have shown that some spliceosome gene mutations can result in immune dysregulation and notable phenotypes due to mis-splicing of immune-related genes. Furthermore, several core spliceosome components harbor splicing-independent immune functions within the cell, expanding the functional repertoire of these diverse proteins.
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Affiliation(s)
- Hui Yang
- Department of Neurosurgery, Huashan Hospital, Shanghai Key laboratory of Brain Function Restoration and Neural Regeneration, MOE Frontiers Center for Brain Science, Institute for Translational Brain Research, Shanghai Medical College, Fudan University, Shanghai, 200032, China
| | - Bruce Beutler
- Center for the Genetics of Host Defense, University of Texas Southwestern Medical Center, Dallas, TX, 75390, USA.
| | - Duanwu Zhang
- Children's Hospital of Fudan University, and Shanghai Key Laboratory of Medical Epigenetics, International Co-laboratory of Medical Epigenetics and Metabolism, Ministry of Science and Technology, Institutes of Biomedical Sciences, Fudan University, Shanghai, 200032, China.
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Germline heterozygous mutations in Nxf1 perturb RNA metabolism and trigger thrombocytopenia and lymphopenia in mice. Blood Adv 2021; 4:1270-1283. [PMID: 32236527 DOI: 10.1182/bloodadvances.2019001323] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/09/2019] [Accepted: 02/28/2020] [Indexed: 02/06/2023] Open
Abstract
In eukaryotic cells, messenger RNA (mRNA) molecules are exported from the nucleus to the cytoplasm, where they are translated. The highly conserved protein nuclear RNA export factor1 (Nxf1) is an important mediator of this process. Although studies in yeast and in human cell lines have shed light on the biochemical mechanisms of Nxf1 function, its contribution to mammalian physiology is less clear. Several groups have identified recurrent NXF1 mutations in chronic lymphocytic leukemia (CLL), placing it alongside several RNA-metabolism factors (including SF3B1, XPO, RPS15) whose dysregulation is thought to contribute to CLL pathogenesis. We report here an allelic series of germline point mutations in murine Nxf1. Mice heterozygous for these loss-of-function Nxf1 mutations exhibit thrombocytopenia and lymphopenia, together with milder hematological defects. This is primarily caused by cell-intrinsic defects in the survival of platelets and peripheral lymphocytes, which are sensitized to intrinsic apoptosis. In contrast, Nxf1 mutations have almost no effect on red blood cell homeostasis. Comparative transcriptome analysis of platelets, lymphocytes, and erythrocytes from Nxf1-mutant mice shows that, in response to impaired Nxf1 function, the cytoplasmic representation of transcripts encoding regulators of RNA metabolism is altered in a unique, lineage-specific way. Thus, blood cell lineages exhibit differential requirements for Nxf1-mediated global mRNA export.
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Forward genetic analysis using OCT screening identifies Sfxn3 mutations leading to progressive outer retinal degeneration in mice. Proc Natl Acad Sci U S A 2020; 117:12931-12942. [PMID: 32457148 DOI: 10.1073/pnas.1921224117] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022] Open
Abstract
Retinal disease and loss of vision can result from any disruption of the complex pathways controlling retinal development and homeostasis. Forward genetics provides an excellent tool to find, in an unbiased manner, genes that are essential to these processes. Using N-ethyl-N-nitrosourea mutagenesis in mice in combination with a screening protocol using optical coherence tomography (OCT) and automated meiotic mapping, we identified 11 mutations presumably causative of retinal phenotypes in genes previously known to be essential for retinal integrity. In addition, we found multiple statistically significant gene-phenotype associations that have not been reported previously and decided to target one of these genes, Sfxn3 (encoding sideroflexin-3), using CRISPR/Cas9 technology. We demonstrate, using OCT, light microscopy, and electroretinography, that two Sfxn3 -/- mouse lines developed progressive and severe outer retinal degeneration. Electron microscopy showed thinning of the retinal pigment epithelium and disruption of the external limiting membrane. Using single-cell RNA sequencing of retinal cells isolated from C57BL/6J mice, we demonstrate that Sfxn3 is expressed in several bipolar cell subtypes, retinal ganglion cells, and some amacrine cell subtypes but not significantly in Müller cells or photoreceptors. In situ hybridization confirmed these findings. Furthermore, pathway analysis suggests that Sfxn3 may be associated with synaptic homeostasis. Importantly, electron microscopy analysis showed disruption of synapses and synaptic ribbons in the outer plexiform layer of Sfxn3 -/- mice. Our work describes a previously unknown requirement for Sfxn3 in retinal function.
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Genetic and structural studies of RABL3 reveal an essential role in lymphoid development and function. Proc Natl Acad Sci U S A 2020; 117:8563-8572. [PMID: 32220963 DOI: 10.1073/pnas.2000703117] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/11/2023] Open
Abstract
The small GTPase RABL3 is an oncogene of unknown physiological function. Homozygous knockout alleles of mouse Rabl3 were embryonic lethal, but a viable hypomorphic allele (xiamen [xm]) causing in-frame deletion of four amino acids from the interswitch region resulted in profound defects in lymphopoiesis. Impaired lymphoid progenitor development led to deficiencies of B cells, T cells, and natural killer (NK) cells in Rabl3 xm/xm mice. T cells and NK cells exhibited impaired cytolytic activity, and mice infected with mouse cytomegalovirus (MCMV) displayed elevated titers in the spleen. Myeloid cells were normal in number and function. Biophysical and crystallographic studies demonstrated that RABL3 formed a homodimer in solution via interactions between the effector binding surfaces on each subunit; monomers adopted a typical small G protein fold. RABL3xm displayed a large compensatory alteration in switch I, which adopted a β-strand configuration normally provided by the deleted interswitch residues, thereby permitting homodimer formation. Dysregulated effector binding due to conformational changes in the switch I-interswitch-switch II module likely underlies the xm phenotype. One such effector may be GPR89, putatively an ion channel or G protein-coupled receptor (GPCR). RABL3, but not RABL3xm, strongly associated with and stabilized GPR89, and an N-ethyl-N-nitrosourea (ENU)-induced mutation (explorer) in Gpr89 phenocopied Rabl3 xm.
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