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Ranjit S, Wang Y, Zhu J, Cheepala SB, Schuetz EG, Cho WJ, Xu B, Robinson CG, Wu G, Naren AP, Schuetz JD. ABCC4 impacts megakaryopoiesis and protects megakaryocytes against 6-mercaptopurine induced cytotoxicity. Drug Resist Updat 2024; 72:101017. [PMID: 37988981 PMCID: PMC10874622 DOI: 10.1016/j.drup.2023.101017] [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: 08/16/2023] [Revised: 10/21/2023] [Accepted: 11/06/2023] [Indexed: 11/23/2023]
Abstract
The role of ABCC4, an ATP-binding cassette transporter, in the process of platelet formation, megakaryopoiesis, is unknown. Here, we show that ABCC4 is highly expressed in megakaryocytes (MKs). Mining of public genomic data (ATAC-seq and genome wide chromatin interactions, Hi-C) revealed that key megakaryopoiesis transcription factors (TFs) interacted with ABCC4 regulatory elements and likely accounted for high ABCC4 expression in MKs. Importantly these genomic interactions for ABCC4 ranked higher than for genes with known roles in megakaryopoiesis suggesting a role for ABCC4 in megakaryopoiesis. We then demonstrate that ABCC4 is required for optimal platelet formation as in vitro differentiation of fetal liver derived MKs from Abcc4-/- mice exhibited impaired proplatelet formation and polyploidization, features required for optimal megakaryopoiesis. Likewise, a human megakaryoblastic cell line, MEG-01 showed that acute ABCC4 inhibition markedly suppressed key processes in megakaryopoiesis and that these effects were related to reduced cAMP export and enhanced dissociation of a negative regulator of megakaryopoiesis, protein kinase A (PKA) from ABCC4. PKA activity concomitantly increased after ABCC4 inhibition which was coupled with significantly reduced GATA-1 expression, a TF needed for optimal megakaryopoiesis. Further, ABCC4 protected MKs from 6-mercaptopurine (6-MP) as Abcc4-/- mice show a profound reduction in MKs after 6-MP treatment. In total, our studies show that ABCC4 not only protects the MKs but is also required for maximal platelet production from MKs, suggesting modulation of ABCC4 function might be a potential therapeutic strategy to regulate platelet production.
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Affiliation(s)
- Sabina Ranjit
- Department of Pharmacy and Pharmaceutical Sciences, St Jude Childres's Research Hospital, USA
| | - Yao Wang
- Department of Pharmacy and Pharmaceutical Sciences, St Jude Childres's Research Hospital, USA
| | - Jingwen Zhu
- Department of Pharmacy and Pharmaceutical Sciences, St Jude Childres's Research Hospital, USA; Department of Pharmaceutical Sciences, University of Tennessee Health Science Center, Memphis, TN, USA
| | - Satish B Cheepala
- Department of Pharmacy and Pharmaceutical Sciences, St Jude Childres's Research Hospital, USA
| | - Erin G Schuetz
- Department of Pharmacy and Pharmaceutical Sciences, St Jude Childres's Research Hospital, USA
| | - Woo Jung Cho
- Cell and Tissue Imaging Center, St Jude Children's Research Hospital, USA
| | - Beisi Xu
- Center for Applied Bioinformatics, St Jude Children's Research Hospital, USA
| | | | - Gang Wu
- Center for Applied Bioinformatics, St Jude Children's Research Hospital, USA
| | - Anjaparavanda P Naren
- Division of Pulmonary Medicine and Critical Care, Cedars-Sinai Medical Center, Los Angeles, CA, USA
| | - John D Schuetz
- Department of Pharmacy and Pharmaceutical Sciences, St Jude Childres's Research Hospital, USA.
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Strauss G, Mott K, Klopocki E, Schulze H. Thrombocytopenia Absent Radius (TAR)-Syndrome: From Current Genetics to Patient Self-Empowerment. Hamostaseologie 2023; 43:252-260. [PMID: 37611607 DOI: 10.1055/a-2088-1801] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 08/25/2023] Open
Abstract
Thrombocytopenia absent radius (TAR) syndrome is a rare form of hereditary thrombocytopenia associated with a bilateral radial aplasia. TAR syndrome is genetically defined by the combination of a microdeletion on chromosome 1 which includes the gene RBM8A, and a single nucleotide polymorphism (SNP) in the second RBM8A allele. While most patients with TAR syndrome harbor a SNP in either the 5' UTR region or in intron 1 of RBM8A, further SNPs associated with TAR syndrome are still being identified. Here, we report on the current understanding of the genetic basis, diagnosis, and therapy of TAR syndrome and discuss patient self-empowerment by enabling networking and exchange between affected individuals and families.
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Affiliation(s)
- Gabriele Strauss
- Department of Paediatric Haematology and Oncology, Helios-Klinikum Buch, Berlin, Germany
| | - Kristina Mott
- Institute of Experimental Biomedicine I, University Hospital Würzburg, Würzburg, Germany
| | - Eva Klopocki
- Institute of Human Genetics, University of Würzburg, Würzburg, Germany
| | - Harald Schulze
- Institute of Experimental Biomedicine I, University Hospital Würzburg, Würzburg, Germany
- Center for Rare Blood Cell Disorders, Center for Rare Diseases, University Hospital Würzburg, Würzburg, Germany
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3
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McSweeney C, Chen M, Dong F, Sebastian A, Reynolds DJ, Mott J, Pei Z, Zou J, Shi Y, Mao Y. Transcriptomic Analyses of Brains of RBM8A Conditional Knockout Mice at Different Developmental Stages Reveal Conserved Signaling Pathways Contributing to Neurodevelopmental Diseases. Int J Mol Sci 2023; 24:4600. [PMID: 36902031 PMCID: PMC10003467 DOI: 10.3390/ijms24054600] [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: 12/31/2022] [Revised: 02/20/2023] [Accepted: 02/22/2023] [Indexed: 03/03/2023] Open
Abstract
RNA-binding motif 8A (RBM8A) is a core component of the exon junction complex (EJC) that binds pre-mRNAs and regulates their splicing, transport, translation, and nonsense-mediated decay (NMD). Dysfunction in the core proteins has been linked to several detriments in brain development and neuropsychiatric diseases. To understand the functional role of Rbm8a in brain development, we have generated brain-specific Rbm8a knockout mice and used next-generation RNA-sequencing to identify differentially expressed genes (DEGs) in mice with heterozygous, conditional knockout (cKO) of Rbm8a in the brain at postnatal day 17 (P17) and at embryonic day 12. Additionally, we analyzed enriched gene clusters and signaling pathways within the DEGs. At the P17 time point, between the control and cKO mice, about 251 significant DEGs were identified. At E12, only 25 DEGs were identified in the hindbrain samples. Bioinformatics analyses have revealed many signaling pathways related to the central nervous system (CNS). When E12 and P17 results were compared, three DEGs, Spp1, Gpnmb, and Top2a, appeared to peak at different developmental time points in the Rbm8a cKO mice. Enrichment analyses suggested altered activity in pathways affecting cellular proliferation, differentiation, and survival. The results support the hypothesis that loss of Rbm8a causes decreased cellular proliferation, increased apoptosis, and early differentiation of neuronal subtypes, which may lead ultimately to an altered neuronal subtype composition in the brain.
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Affiliation(s)
- Colleen McSweeney
- Department of Biology, Pennsylvania State University, University Park, PA 16802, USA
| | - Miranda Chen
- Department of Biology, Pennsylvania State University, University Park, PA 16802, USA
| | - Fengping Dong
- Department of Biology, Pennsylvania State University, University Park, PA 16802, USA
- Department of Genetics, Washington University School of Medicine, St. Louis, MO 63110, USA
| | - Aswathy Sebastian
- Department of Biochemistry and Molecular Biology, Pennsylvania State University, University Park, PA 16802, USA
| | - Derrick James Reynolds
- Department of Microbiology & Molecular Genetics, School of Medicine, University of California, Irvine, CA 92697, USA
| | - Jennifer Mott
- Department of Biology, Pennsylvania State University, University Park, PA 16802, USA
| | - Zifei Pei
- Department of Biology, Pennsylvania State University, University Park, PA 16802, USA
| | - Jizhong Zou
- Systems Biology Center, National Heart, Lung, and Blood Institute, NIH, Bethesda, Rockville, MD 20892, USA
| | - Yongsheng Shi
- Department of Microbiology & Molecular Genetics, School of Medicine, University of California, Irvine, CA 92697, USA
| | - Yingwei Mao
- Department of Biology, Pennsylvania State University, University Park, PA 16802, USA
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Martin H, Rupkey J, Asthana S, Yoon J, Patel S, Mott J, Pei Z, Mao Y. Diverse Roles of the Exon Junction Complex Factors in the Cell Cycle, Cancer, and Neurodevelopmental Disorders-Potential for Therapeutic Targeting. Int J Mol Sci 2022; 23:ijms231810375. [PMID: 36142288 PMCID: PMC9499366 DOI: 10.3390/ijms231810375] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/10/2022] [Revised: 09/01/2022] [Accepted: 09/05/2022] [Indexed: 12/04/2022] Open
Abstract
The exon junction complex (EJC) plays a crucial role in regulating gene expression at the levels of alternative splicing, translation, mRNA localization, and nonsense-mediated decay (NMD). The EJC is comprised of three core proteins: RNA-binding motif 8A (RBM8A), Mago homolog (MAGOH), eukaryotic initiation factor 4A3 (eIF4A3), and a peripheral EJC factor, metastatic lymph node 51 (MLN51), in addition to other peripheral factors whose structural integration is activity-dependent. The physiological and mechanistic roles of the EJC in contribution to molecular, cellular, and organismal level function continue to be explored for potential insights into genetic or pathological dysfunction. The EJC’s specific role in the cell cycle and its implications in cancer and neurodevelopmental disorders prompt enhanced investigation of the EJC as a potential target for these diseases. In this review, we highlight the current understanding of the EJC’s position in the cell cycle, its relation to cancer and developmental diseases, and potential avenues for therapeutic targeting.
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Affiliation(s)
- Hannah Martin
- Department of Biology, Pennsylvania State University, University Park, State College, PA 16802, USA
| | - Julian Rupkey
- Department of Biology, Pennsylvania State University, University Park, State College, PA 16802, USA
| | - Shravan Asthana
- Department of Biology, Pennsylvania State University, University Park, State College, PA 16802, USA
- Feinberg School of Medicine, Northwestern University, 303 East Superior Street, Chicago, IL 60611, USA
| | - Joy Yoon
- Department of Biology, Pennsylvania State University, University Park, State College, PA 16802, USA
| | - Shray Patel
- Department of Biology, Pennsylvania State University, University Park, State College, PA 16802, USA
| | - Jennifer Mott
- Department of Biology, Pennsylvania State University, University Park, State College, PA 16802, USA
| | - Zifei Pei
- Department of Biology, Pennsylvania State University, University Park, State College, PA 16802, USA
| | - Yingwei Mao
- Department of Biology, Pennsylvania State University, University Park, State College, PA 16802, USA
- Correspondence:
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The Physiological Roles of the Exon Junction Complex in Development and Diseases. Cells 2022; 11:cells11071192. [PMID: 35406756 PMCID: PMC8997533 DOI: 10.3390/cells11071192] [Citation(s) in RCA: 8] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/28/2022] [Revised: 03/19/2022] [Accepted: 03/24/2022] [Indexed: 01/12/2023] Open
Abstract
The exon junction complex (EJC) becomes an increasingly important regulator of early gene expression in the central nervous system (CNS) and other tissues. The EJC is comprised of three core proteins: RNA-binding motif 8A (RBM8A), Mago homolog (MAGOH), eukaryotic initiation factor 4A3 (EIF4A3), and a peripheral EJC factor, metastatic lymph node 51 (MLN51), together with various auxiliary factors. The EJC is assembled specifically at exon-exon junctions on mRNAs, hence the name of the complex. The EJC regulates multiple levels of gene expression, from splicing to translation and mRNA degradation. The functional roles of the EJC have been established as crucial to the normal progress of embryonic and neurological development, with wide ranging implications on molecular, cellular, and organism level function. Dysfunction of the EJC has been implicated in multiple developmental and neurological diseases. In this review, we discuss recent progress on the EJC’s physiological roles.
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