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Olasz B, Smithers L, Evans GL, Anandan A, Murcha MW, Vrielink A. Structural analysis of the SAM domain of the Arabidopsis mitochondrial tRNA import receptor. J Biol Chem 2024; 300:107258. [PMID: 38582448 PMCID: PMC11063897 DOI: 10.1016/j.jbc.2024.107258] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/24/2023] [Revised: 03/10/2024] [Accepted: 03/19/2024] [Indexed: 04/08/2024] Open
Abstract
Mitochondria are membrane-bound organelles of endosymbiotic origin with limited protein-coding capacity. The import of nuclear-encoded proteins and nucleic acids is required and essential for maintaining organelle mass, number, and activity. As plant mitochondria do not encode all the necessary tRNA types required, the import of cytosolic tRNA is vital for organelle maintenance. Recently, two mitochondrial outer membrane proteins, named Tric1 and Tric2, for tRNA import component, were shown to be involved in the import of cytosolic tRNA. Tric1/2 binds tRNAalavia conserved residues in the C-terminal Sterile Alpha Motif (SAM) domain. Here we report the X-ray crystal structure of the Tric1 SAM domain. We identified the ability of the SAM domain to form a helical superstructure with six monomers per helical turn and key amino acid residues responsible for its formation. We determined that the oligomerization of the Tric1 SAM domain may play a role in protein function whereby mutation of Gly241 introducing a larger side chain at this position disrupted the oligomer and resulted in the loss of RNA binding capability. Furthermore, complementation of Arabidopsis thaliana Tric1/2 knockout lines with a mutated Tric1 failed to restore the defective plant phenotype. AlphaFold2 structure prediction of both the SAM domain and Tric1 support a cyclic pentameric or hexameric structure. In the case of a hexameric structure, a pore of sufficient dimensions to transfer tRNA across the mitochondrial membrane is observed. Our results highlight the importance of oligomerization of Tric1 for protein function.
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Affiliation(s)
- Bence Olasz
- School of Molecular Sciences, The University of Western Australia, Perth, Western Australia, Australia
| | - Luke Smithers
- School of Molecular Sciences, The University of Western Australia, Perth, Western Australia, Australia
| | - Genevieve L Evans
- School of Molecular Sciences, The University of Western Australia, Perth, Western Australia, Australia
| | - Anandhi Anandan
- School of Molecular Sciences, The University of Western Australia, Perth, Western Australia, Australia
| | - Monika W Murcha
- School of Molecular Sciences, The University of Western Australia, Perth, Western Australia, Australia.
| | - Alice Vrielink
- School of Molecular Sciences, The University of Western Australia, Perth, Western Australia, Australia.
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2
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Wu G, Dong Z, Dong Y, Chen Y, Zhu H, Ding D, Cui Y, Wang Y, Xu Y, Chen H. LncRNA CTBP1-AS inhibits TP63-mediated activation of S100A14 during prostate cancer progression. Cancer Sci 2024; 115:1492-1504. [PMID: 38476086 PMCID: PMC11093200 DOI: 10.1111/cas.16138] [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: 09/17/2023] [Revised: 02/10/2024] [Accepted: 02/20/2024] [Indexed: 03/14/2024] Open
Abstract
Long noncoding RNAs (lncRNAs) have emerged as important molecules and potential new targets for human cancers. This study investigates the function of lncRNA CTBP1 antisense RNA (CTBP1-AS) in prostate cancer (PCa) and explores the entailed molecular mechanism. Aberrantly expressed genes potentially correlated with PCa progression were probed using integrated bioinformatics analyses. A cohort of 68 patients with PCa was included, and their tumor and para-cancerous tissues were collected. CTBP1-AS was highly expressed in PCa tissues and cells and associated with poor patient prognosis. By contrast, tumor protein p63 (TP63) and S100 calcium binding protein A14 (S100A14) were poorly expressed in the PCa tissues and cells. CTBP1-AS did not affect TP63 expression; however it blocked the TP63-mediated transcriptional activation of S100A14, thereby reducing its expression. CTBP1-AS silencing suppressed proliferation, apoptosis resistance, migration, invasion, and tumorigenicity of PCa cell lines, while its overexpression led to inverse results. The malignant phenotype of cells was further weakened by TP63 overexpression but restored following artificial S100A14 silencing. In conclusion, this study demonstrates that CTBP1-AS plays an oncogenic role in PCa by blocking TP63-mediated transcriptional activation of S100A14. This may provide insight into the management of PCa.
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Affiliation(s)
- Guangzheng Wu
- Department of UrologyHarbin Medical University Cancer HospitalHarbinHeilongjiangChina
| | - Zhenkun Dong
- Department of UrologyHarbin Medical University Cancer HospitalHarbinHeilongjiangChina
| | - Yuhang Dong
- Department of UrologyHarbin Medical University Cancer HospitalHarbinHeilongjiangChina
| | - Yinmei Chen
- Department of UrologyHarbin Medical University Cancer HospitalHarbinHeilongjiangChina
| | - Huan Zhu
- Department of UrologyHarbin Medical University Cancer HospitalHarbinHeilongjiangChina
| | - Dexin Ding
- Department of UrologyHarbin Medical University Cancer HospitalHarbinHeilongjiangChina
| | - Yan Cui
- Department of UrologyHarbin Medical University Cancer HospitalHarbinHeilongjiangChina
| | - Yiwen Wang
- Department of UrologyHarbin Medical University Cancer HospitalHarbinHeilongjiangChina
| | - Yangyang Xu
- Department of UrologyHarbin Medical University Cancer HospitalHarbinHeilongjiangChina
| | - Hui Chen
- Department of UrologyHarbin Medical University Cancer HospitalHarbinHeilongjiangChina
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3
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Bhayana S, Dougherty JA, Kamigaki Y, Agrawal S, Wijeratne S, Fitch J, Waller AP, Wolfgang KJ, White P, Kerlin BA, Smoyer WE. Glucocorticoid- and pioglitazone-induced proteinuria reduction in experimental NS both correlate with glomerular ECM modulation. iScience 2024; 27:108631. [PMID: 38188512 PMCID: PMC10770536 DOI: 10.1016/j.isci.2023.108631] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/10/2023] [Revised: 10/31/2023] [Accepted: 11/30/2023] [Indexed: 01/09/2024] Open
Abstract
Idiopathic nephrotic syndrome (NS) is a common glomerular disease. Although glucocorticoids (GC) are the primary treatment, the PPARγ agonist pioglitazone (Pio) also reduces proteinuria in patients with NS and directly protects podocytes from injury. Because both drugs reduce proteinuria, we hypothesized these effects result from overlapping transcriptional patterns. Systems biology approaches compared glomerular transcriptomes from rats with PAN-induced NS treated with GC vs. Pio and identified 29 commonly regulated genes-of-interest, primarily involved in extracellular matrix (ECM) remodeling. Correlation with clinical idiopathic NS patient datasets confirmed glomerular ECM dysregulation as a potential mechanism of injury. Cellular deconvolution in silico revealed GC- and Pio-induced amelioration of altered genes primarily within podocytes and mesangial cells. While validation studies are indicated, these analyses identified molecular pathways involved in the early stages of NS (prior to scarring), suggesting that targeting glomerular ECM dysregulation may enable a future non-immunosuppressive approach for proteinuria reduction in idiopathic NS.
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Affiliation(s)
- Sagar Bhayana
- Center for Clinical and Translational Research, The Abigail Wexner Research Institute at Nationwide Children’s Hospital, Columbus, OH 43205, USA
| | - Julie A. Dougherty
- Center for Clinical and Translational Research, The Abigail Wexner Research Institute at Nationwide Children’s Hospital, Columbus, OH 43205, USA
| | - Yu Kamigaki
- Center for Clinical and Translational Research, The Abigail Wexner Research Institute at Nationwide Children’s Hospital, Columbus, OH 43205, USA
| | - Shipra Agrawal
- Center for Clinical and Translational Research, The Abigail Wexner Research Institute at Nationwide Children’s Hospital, Columbus, OH 43205, USA
- Department of Pediatrics, The Ohio State University College of Medicine, Columbus, OH 43210, USA
| | - Saranga Wijeratne
- Institute for Genomic Medicine, The Abigail Wexner Research Institute at Nationwide Children’s Hospital, Columbus, OH 43205, USA
| | - James Fitch
- Institute for Genomic Medicine, The Abigail Wexner Research Institute at Nationwide Children’s Hospital, Columbus, OH 43205, USA
| | - Amanda P. Waller
- Center for Clinical and Translational Research, The Abigail Wexner Research Institute at Nationwide Children’s Hospital, Columbus, OH 43205, USA
| | - Katelyn J. Wolfgang
- Center for Clinical and Translational Research, The Abigail Wexner Research Institute at Nationwide Children’s Hospital, Columbus, OH 43205, USA
| | - Peter White
- Department of Pediatrics, The Ohio State University College of Medicine, Columbus, OH 43210, USA
- Institute for Genomic Medicine, The Abigail Wexner Research Institute at Nationwide Children’s Hospital, Columbus, OH 43205, USA
| | - Bryce A. Kerlin
- Center for Clinical and Translational Research, The Abigail Wexner Research Institute at Nationwide Children’s Hospital, Columbus, OH 43205, USA
- Department of Pediatrics, The Ohio State University College of Medicine, Columbus, OH 43210, USA
| | - William E. Smoyer
- Center for Clinical and Translational Research, The Abigail Wexner Research Institute at Nationwide Children’s Hospital, Columbus, OH 43205, USA
- Department of Pediatrics, The Ohio State University College of Medicine, Columbus, OH 43210, USA
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4
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Paul MS, Michener SL, Pan H, Chan H, Pfliger JM, Rosenfeld JA, Lerma VC, Tran A, Longley MA, Lewis RA, Weisz-Hubshman M, Bekheirnia MR, Bekheirnia N, Massingham L, Zech M, Wagner M, Engels H, Cremer K, Mangold E, Peters S, Trautmann J, Mester JL, Guillen Sacoto MJ, Person R, McDonnell PP, Cohen SR, Lusk L, Cohen ASA, Le Pichon JB, Pastinen T, Zhou D, Engleman K, Racine C, Faivre L, Moutton S, Denommé-Pichon AS, Koh HY, Poduri A, Bolton J, Knopp C, Julia Suh DS, Maier A, Toosi MB, Karimiani EG, Maroofian R, Schaefer GB, Ramakumaran V, Vasudevan P, Prasad C, Osmond M, Schuhmann S, Vasileiou G, Russ-Hall S, Scheffer IE, Carvill GL, Mefford H, Bacino CA, Lee BH, Chao HT. A syndromic neurodevelopmental disorder caused by rare variants in PPFIA3. Am J Hum Genet 2024; 111:96-118. [PMID: 38181735 PMCID: PMC10806447 DOI: 10.1016/j.ajhg.2023.12.004] [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: 04/06/2023] [Revised: 12/01/2023] [Accepted: 12/04/2023] [Indexed: 01/07/2024] Open
Abstract
PPFIA3 encodes the protein-tyrosine phosphatase, receptor-type, F-polypeptide-interacting-protein-alpha-3 (PPFIA3), which is a member of the LAR-protein-tyrosine phosphatase-interacting-protein (liprin) family involved in synapse formation and function, synaptic vesicle transport, and presynaptic active zone assembly. The protein structure and function are evolutionarily well conserved, but human diseases related to PPFIA3 dysfunction are not yet reported in OMIM. Here, we report 20 individuals with rare PPFIA3 variants (19 heterozygous and 1 compound heterozygous) presenting with developmental delay, intellectual disability, hypotonia, dysmorphisms, microcephaly or macrocephaly, autistic features, and epilepsy with reduced penetrance. Seventeen unique PPFIA3 variants were detected in 18 families. To determine the pathogenicity of PPFIA3 variants in vivo, we generated transgenic fruit flies producing either human wild-type (WT) PPFIA3 or five missense variants using GAL4-UAS targeted gene expression systems. In the fly overexpression assays, we found that the PPFIA3 variants in the region encoding the N-terminal coiled-coil domain exhibited stronger phenotypes compared to those affecting the C-terminal region. In the loss-of-function fly assay, we show that the homozygous loss of fly Liprin-α leads to embryonic lethality. This lethality is partially rescued by the expression of human PPFIA3 WT, suggesting human PPFIA3 function is partially conserved in the fly. However, two of the tested variants failed to rescue the lethality at the larval stage and one variant failed to rescue lethality at the adult stage. Altogether, the human and fruit fly data reveal that the rare PPFIA3 variants are dominant-negative loss-of-function alleles that perturb multiple developmental processes and synapse formation.
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Affiliation(s)
- Maimuna S Paul
- Department of Pediatrics, Section of Neurology and Developmental Neuroscience, Baylor College of Medicine, Houston, TX, USA; Jan and Dan Duncan Neurological Research Institute, Texas Children's Hospital, Houston, TX, USA; Cain Pediatric Neurology Research Foundation Laboratories, Jan and Dan Duncan Neurological Research Institute, Houston, TX, USA
| | - Sydney L Michener
- Department of Pediatrics, Section of Neurology and Developmental Neuroscience, Baylor College of Medicine, Houston, TX, USA; Jan and Dan Duncan Neurological Research Institute, Texas Children's Hospital, Houston, TX, USA; Cain Pediatric Neurology Research Foundation Laboratories, Jan and Dan Duncan Neurological Research Institute, Houston, TX, USA
| | - Hongling Pan
- Jan and Dan Duncan Neurological Research Institute, Texas Children's Hospital, Houston, TX, USA; Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, TX, USA
| | - Hiuling Chan
- Cain Pediatric Neurology Research Foundation Laboratories, Jan and Dan Duncan Neurological Research Institute, Houston, TX, USA; Augustana College, Rock Island, IL, USA; Summer Undergraduate Research Training (SMART) Program, Baylor College of Medicine, Houston, TX, USA
| | - Jessica M Pfliger
- Department of Pediatrics, Section of Neurology and Developmental Neuroscience, Baylor College of Medicine, Houston, TX, USA; Jan and Dan Duncan Neurological Research Institute, Texas Children's Hospital, Houston, TX, USA; Graduate Program in Electrical and Computer Engineering, Rice University, Houston, TX, USA
| | - Jill A Rosenfeld
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, TX, USA
| | - Vanesa C Lerma
- Department of Pediatrics, Section of Neurology and Developmental Neuroscience, Baylor College of Medicine, Houston, TX, USA; Jan and Dan Duncan Neurological Research Institute, Texas Children's Hospital, Houston, TX, USA; Department of Psychology, University of Houston, Houston, TX, USA
| | - Alyssa Tran
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, TX, USA
| | - Megan A Longley
- Department of Pediatrics, Section of Neurology and Developmental Neuroscience, Baylor College of Medicine, Houston, TX, USA; Jan and Dan Duncan Neurological Research Institute, Texas Children's Hospital, Houston, TX, USA
| | - Richard A Lewis
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, TX, USA; Department of Ophthalmology, Baylor College of Medicine, Houston, TX, USA
| | - Monika Weisz-Hubshman
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, TX, USA
| | - Mir Reza Bekheirnia
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, TX, USA; Renal Genetics Clinic, Baylor College of Medicine, Houston, TX, USA
| | - Nasim Bekheirnia
- Renal Genetics Clinic, Baylor College of Medicine, Houston, TX, USA
| | - Lauren Massingham
- Rhode Island Hospital and Hasbro Children's Hospital, Providence, RI, USA
| | - Michael Zech
- Institute of Neurogenomics, Helmholtz Zentrum München, Munich, Germany; Institute of Human Genetics, School of Medicine, Technical University, Munich, Germany; Institute for Advanced Study, Technical University of Munich, Garching, Germany
| | - Matias Wagner
- Institute of Neurogenomics, Helmholtz Zentrum München, Munich, Germany; Institute of Human Genetics, School of Medicine, Technical University, Munich, Germany; Division of Pediatric Neurology, Developmental Neurology and Social Pediatrics, Dr. von Hauner Children's Hospital, Munich, Germany
| | - Hartmut Engels
- Institute of Human Genetics, School of Medicine, University Hospital Bonn, University of Bonn, Bonn, Germany
| | - Kirsten Cremer
- Division of Pediatric Neurology, Developmental Neurology and Social Pediatrics, Dr. von Hauner Children's Hospital, Munich, Germany
| | - Elisabeth Mangold
- Division of Pediatric Neurology, Developmental Neurology and Social Pediatrics, Dr. von Hauner Children's Hospital, Munich, Germany
| | - Sophia Peters
- Division of Pediatric Neurology, Developmental Neurology and Social Pediatrics, Dr. von Hauner Children's Hospital, Munich, Germany
| | - Jessica Trautmann
- Division of Pediatric Neurology, Developmental Neurology and Social Pediatrics, Dr. von Hauner Children's Hospital, Munich, Germany
| | | | | | | | - Pamela P McDonnell
- Epilepsy NeuroGenetics Initiative (ENGIN), Division of Neurology, Children's Hospital of Philadelphia, Philadelphia, PA, USA; Department of Neurology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, USA
| | - Stacey R Cohen
- Epilepsy NeuroGenetics Initiative (ENGIN), Division of Neurology, Children's Hospital of Philadelphia, Philadelphia, PA, USA
| | - Laina Lusk
- Epilepsy NeuroGenetics Initiative (ENGIN), Division of Neurology, Children's Hospital of Philadelphia, Philadelphia, PA, USA
| | - Ana S A Cohen
- Children's Mercy Kansas City, Genomic Medicine Center, The University of Missouri-Kansas City (UMKC), School of Medicine, Kansas City, MO, USA
| | | | - Tomi Pastinen
- Children's Mercy Kansas City, Genomic Medicine Center, The University of Missouri-Kansas City (UMKC), School of Medicine, Kansas City, MO, USA; Children's Mercy Research Institute, Kansas City, MO, USA
| | - Dihong Zhou
- Children's Mercy Hospital, Kansas City, MO, USA
| | | | - Caroline Racine
- University Hospital, Dijon, France; INSERM UMR1231 GAD "Génétique des Anomalies Du Développement," FHU-TRANSLAD, University of Burgundy, Dijon, France; Functional Unit for Diagnostic Innovation in Rare Diseases, FHU-TRANSLAD, Dijon Bourgogne, France
| | - Laurence Faivre
- Functional Unit for Diagnostic Innovation in Rare Diseases, FHU-TRANSLAD, Dijon Bourgogne, France; Department of Genetics and Reference Center for Development Disorders and Intellectual Disabilities, FHU-TRANSLAD and GIMI Institute, Dijon Bourgogne University Hospital, Dijon, France
| | - Sébastien Moutton
- Functional Unit for Diagnostic Innovation in Rare Diseases, FHU-TRANSLAD, Dijon Bourgogne, France; Department of Genetics and Reference Center for Development Disorders and Intellectual Disabilities, FHU-TRANSLAD and GIMI Institute, Dijon Bourgogne University Hospital, Dijon, France
| | - Anne-Sophie Denommé-Pichon
- University Hospital, Dijon, France; INSERM UMR1231 GAD "Génétique des Anomalies Du Développement," FHU-TRANSLAD, University of Burgundy, Dijon, France; Functional Unit for Diagnostic Innovation in Rare Diseases, FHU-TRANSLAD, Dijon Bourgogne, France
| | - Hyun Yong Koh
- Department of Pediatrics, Section of Neurology and Developmental Neuroscience, Baylor College of Medicine, Houston, TX, USA; Department of Neurology, Boston Children's Hospital, Boston, MA, USA
| | - Annapurna Poduri
- Department of Neurology, Boston Children's Hospital, Boston, MA, USA
| | - Jeffrey Bolton
- Department of Neurology, Boston Children's Hospital, Boston, MA, USA
| | - Cordula Knopp
- Institute for Human Genetics and Genomic Medicine, Medical Faculty, RWTH, Aachen University, Aachen, Germany
| | - Dong Sun Julia Suh
- Institute for Human Genetics and Genomic Medicine, Medical Faculty, RWTH, Aachen University, Aachen, Germany
| | - Andrea Maier
- Medical Treatment Center for Adults with Intellectual Disabilities and/or Severe Multiple Disabilities (MZEB), RWTH Aachen University Hospital, Aachen, Germany
| | - Mehran Beiraghi Toosi
- Department of Pediatrics, School of Medicine, Mashhad University of Medical Sciences, Mashhad, Iran; Neuroscience Research Center, Mashhad University of Medical Sciences, Mashhad, Iran
| | - Ehsan Ghayoor Karimiani
- Department of Medical Genetics, Next Generation Genetic Polyclinic, Mashhad, Iran; Molecular and Clinical Sciences Institute, St. George's, University of London, Cranmer Terrace, London, UK
| | - Reza Maroofian
- Department of Neuromuscular Diseases, UCL Queen Square Institute of Neurology, London, UK
| | | | | | - Pradeep Vasudevan
- LNR Genomics Medicine, University Hospitals of Leicester, Leicester, UK
| | - Chitra Prasad
- London Health Sciences Centre, and Division of Medical Genetics, Department of Pediatrics, Western University, London, ON, Canada
| | - Matthew Osmond
- Children's Hospital of Eastern Ontario Research Institute, University of Ottawa, ON, Canada
| | - Sarah Schuhmann
- Institute of Human Genetics, Universitätsklinikum Erlangen, Friedrich-Alexander-Universität Erlangen-Nürnberg, Erlangen, Germany
| | - Georgia Vasileiou
- Institute of Human Genetics, Universitätsklinikum Erlangen, Friedrich-Alexander-Universität Erlangen-Nürnberg, Erlangen, Germany
| | - Sophie Russ-Hall
- Epilepsy Research Centre, Department of Medicine, University of Melbourne, Austin Health, VIC, Australia
| | - Ingrid E Scheffer
- Epilepsy Research Centre, Department of Medicine, University of Melbourne, Austin Health, VIC, Australia; Department of Pediatrics, University of Melbourne, Royal Children's Hospital, Florey and Murdoch Children's Research Institutes, VIC, Melbourne, Australia
| | - Gemma L Carvill
- Department of Neurology, Northwestern University Feinberg School of Medicine, Chicago, IL, USA
| | - Heather Mefford
- Center for Pediatric Neurological Disease Research, St. Jude Children's Research Hospital, Memphis, TN, USA
| | - Carlos A Bacino
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, TX, USA; Texas Children's Hospital, Houston, TX, USA
| | - Brendan H Lee
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, TX, USA; Texas Children's Hospital, Houston, TX, USA
| | - Hsiao-Tuan Chao
- Department of Pediatrics, Section of Neurology and Developmental Neuroscience, Baylor College of Medicine, Houston, TX, USA; Jan and Dan Duncan Neurological Research Institute, Texas Children's Hospital, Houston, TX, USA; Cain Pediatric Neurology Research Foundation Laboratories, Jan and Dan Duncan Neurological Research Institute, Houston, TX, USA; Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, TX, USA; Texas Children's Hospital, Houston, TX, USA; Department of Neuroscience, Baylor College of Medicine, Houston, TX, USA; McNair Medical Institute, The Robert and Janice McNair Foundation, Houston, TX, USA.
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5
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Ray S, Hewitt K. Sticky, Adaptable, and Many-sided: SAM protein versatility in normal and pathological hematopoietic states. Bioessays 2023; 45:e2300022. [PMID: 37318311 PMCID: PMC10527593 DOI: 10.1002/bies.202300022] [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: 02/01/2023] [Revised: 05/10/2023] [Accepted: 05/15/2023] [Indexed: 06/16/2023]
Abstract
With decades of research seeking to generalize sterile alpha motif (SAM) biology, many outstanding questions remain regarding this multi-tool protein module. Recent data from structural and molecular/cell biology has begun to reveal new SAM modes of action in cell signaling cascades and biomolecular condensation. SAM-dependent mechanisms underlie blood-related (hematologic) diseases, including myelodysplastic syndromes and leukemias, prompting our focus on hematopoiesis for this review. With the increasing coverage of SAM-dependent interactomes, a hypothesis emerges that SAM interaction partners and binding affinities work to fine tune cell signaling cascades in developmental and disease contexts, including hematopoiesis and hematologic disease. This review discusses what is known and remains unknown about the standard mechanisms and neoplastic properties of SAM domains and what the future might hold for developing SAM-targeted therapies.
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Affiliation(s)
- Suhita Ray
- Department of Genetics, Cell Biology and Anatomy, University of Nebraska Medical Center, Omaha, NE, 68198, United States
| | - Kyle Hewitt
- Department of Genetics, Cell Biology and Anatomy, University of Nebraska Medical Center, Omaha, NE, 68198, United States
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6
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Seo JJ, Jung SJ, Yang J, Choi DE, Kim VN. Functional viromic screens uncover regulatory RNA elements. Cell 2023:S0092-8674(23)00675-X. [PMID: 37413987 DOI: 10.1016/j.cell.2023.06.007] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/12/2022] [Revised: 04/21/2023] [Accepted: 06/10/2023] [Indexed: 07/08/2023]
Abstract
The number of sequenced viral genomes has surged recently, presenting an opportunity to understand viral diversity and uncover unknown regulatory mechanisms. Here, we conducted a screening of 30,367 viral segments from 143 species representing 96 genera and 37 families. Using a library of viral segments in 3' UTR, we identified hundreds of elements impacting RNA abundance, translation, and nucleocytoplasmic distribution. To illustrate the power of this approach, we investigated K5, an element conserved in kobuviruses, and found its potent ability to enhance mRNA stability and translation in various contexts, including adeno-associated viral vectors and synthetic mRNAs. Moreover, we identified a previously uncharacterized protein, ZCCHC2, as a critical host factor for K5. ZCCHC2 recruits the terminal nucleotidyl transferase TENT4 to elongate poly(A) tails with mixed sequences, delaying deadenylation. This study provides a unique resource for virus and RNA research and highlights the potential of the virosphere for biological discoveries.
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Affiliation(s)
- Jenny J Seo
- Center for RNA Research, Institute for Basic Science, Seoul 08826, Republic of Korea; School of Biological Sciences, Seoul National University, Seoul 08826, Republic of Korea
| | - Soo-Jin Jung
- Center for RNA Research, Institute for Basic Science, Seoul 08826, Republic of Korea; School of Biological Sciences, Seoul National University, Seoul 08826, Republic of Korea
| | - Jihye Yang
- Center for RNA Research, Institute for Basic Science, Seoul 08826, Republic of Korea; School of Biological Sciences, Seoul National University, Seoul 08826, Republic of Korea
| | - Da-Eun Choi
- Center for RNA Research, Institute for Basic Science, Seoul 08826, Republic of Korea; School of Biological Sciences, Seoul National University, Seoul 08826, Republic of Korea
| | - V Narry Kim
- Center for RNA Research, Institute for Basic Science, Seoul 08826, Republic of Korea; School of Biological Sciences, Seoul National University, Seoul 08826, Republic of Korea.
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7
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Clements CM, Henen MA, Vögeli B, Shellman YG. The Structural Dynamics, Complexity of Interactions, and Functions in Cancer of Multi-SAM Containing Proteins. Cancers (Basel) 2023; 15:3019. [PMID: 37296980 PMCID: PMC10252437 DOI: 10.3390/cancers15113019] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/28/2023] [Revised: 05/25/2023] [Accepted: 05/30/2023] [Indexed: 06/12/2023] Open
Abstract
SAM domains are crucial mediators of diverse interactions, including those important for tumorigenesis or metastasis of cancers, and thus SAM domains can be attractive targets for developing cancer therapies. This review aims to explore the literature, especially on the recent findings of the structural dynamics, regulation, and functions of SAM domains in proteins containing more than one SAM (multi-SAM containing proteins, MSCPs). The topics here include how intrinsic disorder of some SAMs and an additional SAM domain in MSCPs increase the complexity of their interactions and oligomerization arrangements. Many similarities exist among these MSCPs, including their effects on cancer cell adhesion, migration, and metastasis. In addition, they are all involved in some types of receptor-mediated signaling and neurology-related functions or diseases, although the specific receptors and functions vary. This review also provides a simple outline of methods for studying protein domains, which may help non-structural biologists to reach out and build new collaborations to study their favorite protein domains/regions. Overall, this review aims to provide representative examples of various scenarios that may provide clues to better understand the roles of SAM domains and MSCPs in cancer in general.
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Affiliation(s)
- Christopher M. Clements
- Department of Dermatology, School of Medicine, University of Colorado Anschutz Medical Campus, Aurora, CO 80045, USA;
| | - Morkos A. Henen
- Department of Biochemistry and Molecular Genetics, School of Medicine, University of Colorado Anschutz Medical Campus, Aurora, CO 80045, USA; (M.A.H.); (B.V.)
| | - Beat Vögeli
- Department of Biochemistry and Molecular Genetics, School of Medicine, University of Colorado Anschutz Medical Campus, Aurora, CO 80045, USA; (M.A.H.); (B.V.)
| | - Yiqun G. Shellman
- Department of Dermatology, School of Medicine, University of Colorado Anschutz Medical Campus, Aurora, CO 80045, USA;
- Charles C. Gates Regenerative Medicine and Stem Cell Biology Institute, University of Colorado Anschutz Medical Campus, Aurora, CO 80045, USA
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8
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Paul MS, Michener SL, Pan H, Pfliger JM, Rosenfeld JA, Lerma VC, Tran A, Longley MA, Lewis RA, Weisz-Hubshman M, Bekheirnia MR, Bekheirnia N, Massingham L, Zech M, Wagner M, Engels H, Cremer K, Mangold E, Peters S, Trautmann J, Mester JL, Guillen Sacoto MJ, Person R, McDonnell PP, Cohen SR, Lusk L, Cohen ASA, Pichon JBL, Pastinen T, Zhou D, Engleman K, Racine C, Faivre L, Moutton S, Pichon ASD, Schuhmann S, Vasileiou G, Russ-Hall S, Scheffer IE, Carvill GL, Mefford H, Network UD, Bacino CA, Lee BH, Chao HT. Rare variants in PPFIA3 cause delayed development, intellectual disability, autism, and epilepsy. MEDRXIV : THE PREPRINT SERVER FOR HEALTH SCIENCES 2023:2023.03.27.23287689. [PMID: 37034625 PMCID: PMC10081396 DOI: 10.1101/2023.03.27.23287689] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/19/2023]
Abstract
PPFIA3 encodes the Protein-Tyrosine Phosphatase, Receptor-Type, F Polypeptide-Interacting Protein Alpha-3 (PPFIA3), which is a member of the LAR protein-tyrosine phosphatase-interacting protein (liprin) family involved in synaptic vesicle transport and presynaptic active zone assembly. The protein structure and function are well conserved in both invertebrates and vertebrates, but human diseases related to PPFIA3 dysfunction are not yet known. Here, we report 14 individuals with rare mono-allelic PPFIA3 variants presenting with features including developmental delay, intellectual disability, hypotonia, autism, and epilepsy. To determine the pathogenicity of PPFIA3 variants in vivo , we generated transgenic fruit flies expressing either human PPFIA3 wildtype (WT) or variant protein using GAL4-UAS targeted gene expression systems. Ubiquitous expression with Actin-GAL4 showed that the PPFIA3 variants had variable penetrance of pupal lethality, eclosion defects, and anatomical leg defects. Neuronal expression with elav-GAL4 showed that the PPFIA3 variants had seizure-like behaviors, motor defects, and bouton loss at the 3 rd instar larval neuromuscular junction (NMJ). Altogether, in the fly overexpression assays, we found that the PPFIA3 variants in the N-terminal coiled coil domain exhibited stronger phenotypes compared to those in the C-terminal region. In the loss-of-function fly assay, we show that the homozygous loss of fly Liprin- α leads to embryonic lethality. This lethality is partially rescued by the expression of human PPFIA3 WT, suggesting human PPFIA3 protein function is partially conserved in the fly. However, the PPFIA3 variants failed to rescue lethality. Altogether, the human and fruit fly data reveal that the rare PPFIA3 variants are dominant negative loss-of-function alleles that perturb multiple developmental processes and synapse formation.
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9
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Wang XY, Zhang LN. RNA binding protein SAMD4: current knowledge and future perspectives. Cell Biosci 2023; 13:21. [PMID: 36732864 PMCID: PMC9893680 DOI: 10.1186/s13578-023-00968-x] [Citation(s) in RCA: 5] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/09/2022] [Accepted: 01/22/2023] [Indexed: 02/04/2023] Open
Abstract
SAMD4 protein family is a class of novel RNA-binding proteins that can mediate post-transcriptional regulation and translation repression in eukaryotes, which are highly conserved from yeast to humans during evolution. In mammalian cells, SAMD4 protein family consists of two members including SAMD4A/Smaug1 and SAMD4B/Smaug2, both of which contain common SAM domain that can specifically bind to different target mRNAs through stem-loop structures, also known as Smaug recognition elements (SREs), and regulate the mRNA stability, degradation and translation. In addition, SAMD4 can form the cytoplasmic mRNA silencing foci and regulate the translation of SRE-containing mRNAs in neurons. SAMD4 also can form the cytosolic membrane-less organelles (MLOs), termed as Smaug1 bodies, and regulate mitochondrial function. Importantly, many studies have identified that SAMD4 family members are involved in various pathological processes including myopathy, bone development, neural development, and cancer occurrence and progression. In this review, we mainly summarize the structural characteristics, biological functions and molecular regulatory mechanisms of SAMD4 protein family members, which will provide a basis for further research and clinical application of SAMD4 protein family.
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Affiliation(s)
- Xin-Ya Wang
- grid.28703.3e0000 0000 9040 3743Beijing International Science and Technology Cooperation Base of Antivirus Drug, Faculty of Environment and Life, Beijing University of Technology, 100124 Beijing, People’s Republic of China
| | - Li-Na Zhang
- grid.28703.3e0000 0000 9040 3743Beijing International Science and Technology Cooperation Base of Antivirus Drug, Faculty of Environment and Life, Beijing University of Technology, 100124 Beijing, People’s Republic of China
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10
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Clements CM, Vögeli B, Shellman YG, Henen MA. SAM1 domain of SASH1 harbors distinctive structural heterogeneity. J Struct Biol 2022; 214:107914. [PMID: 36341956 PMCID: PMC9733425 DOI: 10.1016/j.jsb.2022.107914] [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: 07/24/2022] [Revised: 09/28/2022] [Accepted: 10/25/2022] [Indexed: 11/06/2022]
Abstract
The sterile alpha motif (SAM) domains are among the most versatile protein domains in biology, and the variety of the oligomerization states contribute to their diverse roles in many diseases. A better understanding of the structure and dynamics of various SAM domains will provide a scientific basis for drug development targeting them. Here, we used SEC-MALS, HPLC, NMR, and other biophysical techniques to characterize the structural features and dynamics of the SAM1 domain in SASH1. SASH1 is a scaffold protein belonging to the same family as SASH3. Unlike the dimerization seen in SASH3's SAM domain, our SEC-MALS and SE-HPLC showed that SAM1 exists primarily as a less compact monomer with a minor oligomer. NMR assignment, relaxation, and exchange experiments revealed the presence of both a disordered monomer and a more structured oligomer with multiple timescale exchange regimes in solution. Mutagenesis and SE-HPLC showed that D663A/T664K substitutions in SAM1 increased its oligomerization. In sum, this study is the first to characterize a disordered structure for a SAM domain, provides additional evidence and framework for the diversity of SAM domains, and identifies a region in SAM1 as a potential starting point to further characterize the structural mechanism of oligomerization of the domain.
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Affiliation(s)
- Christopher M Clements
- Department of Dermatology, School of Medicine, University of Colorado Anschutz Medical Campus, Aurora, CO, USA.
| | - Beat Vögeli
- Department of Biochemistry and Molecular Genetics, School of Medicine, University of Colorado Anschutz Medical Campus, Aurora, CO, USA.
| | - Yiqun G Shellman
- Department of Dermatology, School of Medicine, University of Colorado Anschutz Medical Campus, Aurora, CO, USA.
| | - Morkos A Henen
- Department of Biochemistry and Molecular Genetics, School of Medicine, University of Colorado Anschutz Medical Campus, Aurora, CO, USA.
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11
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Fernández-Alvarez AJ, Thomas MG, Pascual ML, Habif M, Pimentel J, Corbat AA, Pessoa JP, La Spina PE, Boscaglia L, Plessis A, Carmo-Fonseca M, Grecco HE, Casado M, Boccaccio GL. Smaug1 membrane-less organelles respond to AMPK/mTOR and affect mitochondrial function‡. J Cell Sci 2021; 135:273619. [PMID: 34859817 DOI: 10.1242/jcs.253591] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/09/2020] [Accepted: 11/15/2021] [Indexed: 11/20/2022] Open
Abstract
Smaug is a conserved translational regulator that binds numerous mRNAs, including nuclear transcripts that encode mitochondrial enzymes. Smaug orthologs form cytosolic membrane-less organelles (MLOs) in several organisms and cell types. We have performed single-molecule FISH assays that revealed that SDHB and UQCRC1 mRNAs associate with Smaug1 bodies in U2OS cells. Loss of function of Smaug1 and Smaug2 affected both mitochondrial respiration and morphology of the mitochondrial network. Phenotype rescue by Smaug1 transfection depends on the presence of its RNA binding domain. Moreover, we identified specific Smaug1 domains involved in MLO formation, and found that impaired Smaug1 MLO condensation correlates with mitochondrial defects. Mitochondrial Complex I inhibition by rotenone -but not strong mitochondrial uncoupling by CCCP- rapidly induced Smaug1 MLOs dissolution. Metformin and rapamycin elicited similar effects, which were blocked by pharmacological inhibition of AMPK. Finally, we found that Smaug1 MLO dissolution weakens the interaction with target mRNAs, thus enabling their release. We propose that mitochondrial respiration and the AMPK/mTOR balance controls the condensation and dissolution of Smaug1 MLOs, thus regulating nuclear mRNAs that encode key mitochondrial proteins.
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Affiliation(s)
- Ana J Fernández-Alvarez
- Fundación Instituto Leloir (FIL).,Instituto de Investigaciones Bioquímicas de Buenos Aires (IIBBA) - Consejo Nacional de Investigaciones Científicas y Tecnológicas (CONICET), C1405BWE Buenos Aires, Argentina
| | - María Gabriela Thomas
- Fundación Instituto Leloir (FIL).,Instituto de Investigaciones Bioquímicas de Buenos Aires (IIBBA) - Consejo Nacional de Investigaciones Científicas y Tecnológicas (CONICET), C1405BWE Buenos Aires, Argentina
| | - Malena L Pascual
- Fundación Instituto Leloir (FIL).,Instituto de Investigaciones Bioquímicas de Buenos Aires (IIBBA) - Consejo Nacional de Investigaciones Científicas y Tecnológicas (CONICET), C1405BWE Buenos Aires, Argentina
| | - Martín Habif
- Department of Physics, Facultad de Ciencias Exactas y Naturales (FCEN), University of Buenos Aires, and IFIBA, CONICET, C1428EHA Buenos Aires, Argentina
| | - Jerónimo Pimentel
- Fundación Instituto Leloir (FIL).,Instituto de Investigaciones Bioquímicas de Buenos Aires (IIBBA) - Consejo Nacional de Investigaciones Científicas y Tecnológicas (CONICET), C1405BWE Buenos Aires, Argentina
| | - Agustín A Corbat
- Department of Physics, Facultad de Ciencias Exactas y Naturales (FCEN), University of Buenos Aires, and IFIBA, CONICET, C1428EHA Buenos Aires, Argentina
| | - João P Pessoa
- Instituto de Medicina Molecular João Lobo Antunes, Faculdade de Medicina, Universidade de Lisboa, Lisboa, Portugal
| | - Pablo E La Spina
- Fundación Instituto Leloir (FIL).,Instituto de Investigaciones Bioquímicas de Buenos Aires (IIBBA) - Consejo Nacional de Investigaciones Científicas y Tecnológicas (CONICET), C1405BWE Buenos Aires, Argentina
| | | | - Anne Plessis
- Institut Jacques Monod, CNRS, UMR 7592, University Paris Diderot, Sorbonne Paris Cité, F-75205 Paris, France
| | - Maria Carmo-Fonseca
- Instituto de Medicina Molecular João Lobo Antunes, Faculdade de Medicina, Universidade de Lisboa, Lisboa, Portugal
| | - Hernán E Grecco
- Department of Physics, Facultad de Ciencias Exactas y Naturales (FCEN), University of Buenos Aires, and IFIBA, CONICET, C1428EHA Buenos Aires, Argentina
| | - Marta Casado
- Instituto de Biomedicina de Valencia, IBV-CSIC, Valencia 46010, Spain, and Centro de Investigación Biomédica en Red de Enfermedades Hepáticas y Digestivas (CIBERehd), Madrid 28029, Spain
| | - Graciela L Boccaccio
- Fundación Instituto Leloir (FIL).,Instituto de Investigaciones Bioquímicas de Buenos Aires (IIBBA) - Consejo Nacional de Investigaciones Científicas y Tecnológicas (CONICET), C1405BWE Buenos Aires, Argentina.,Department of Molecular and Cellular Biology and Physiology (FBMyC), Facultad de Ciencias Exactas y Naturales (FCEN), University of Buenos Aires, C1428EHA Buenos Aires, Argentina
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12
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Zhou M, Wang B, Li H, Han J, Li A, Lu W. RNA-binding protein SAMD4A inhibits breast tumor angiogenesis by modulating the balance of angiogenesis program. Cancer Sci 2021; 112:3835-3845. [PMID: 34219323 PMCID: PMC8409301 DOI: 10.1111/cas.15053] [Citation(s) in RCA: 12] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/11/2021] [Revised: 06/22/2021] [Accepted: 06/29/2021] [Indexed: 12/13/2022] Open
Abstract
Tumor-induced angiogenesis is important for further progression of solid tumors. The initiation of tumor angiogenesis is dictated by a shift in the balance between proangiogenic and antiangiogenic gene expression programs. However, the potential mechanism controlling the expression of angiogenesis-related genes in the tumor cells, especially the process mediated by RNA-binding protein (RBP) remains unclear. SAMD4A is a conserved RBP across fly to mammals, and is believed to play an important role in controlling gene translation and stability. In this study, we identified the potential role of SAMD4A in modulating angiogenesis-related gene expression and tumor progression in breast cancer. SAMD4A expression was repressed in breast cancer tissues and cells and low SAMD4A expression in human breast tumor samples was strongly associated with poor survival of patients. Overexpression of SAMD4A inhibited breast tumor angiogenesis and caner progression, whereas knockdown of SAMD4A demonstrated a reversed effect. Mechanistically, SAMD4A was found to specifically destabilize the proangiogenic gene transcripts, including C-X-C motif chemokine ligand 5 (CXCL5), endoglin (ENG), interleukin 1β (IL1β), and angiopoietin 1 (ANGPT1), by directly interacting with the stem-loop structure in the 3' untranslated region (3'UTR) of these mRNAs through its sterile alpha motif (SAM) domain, resulting in the imbalance of angiogenic genes expression. Collectively, our results suggest that SAMD4A is a novel breast tumor suppressor that inhibits tumor angiogenesis by specifically downregulating the expression of proangiogenic genes, which might be a potential antiangiogenic target for breast cancer therapy.
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Affiliation(s)
- Meicen Zhou
- Department of Endocrinology, Beijing Jishuitan Hospital, The 4th Clinical Medical College of Peking University, Beijing, China
| | - Bing Wang
- Institute of Microcirculation, Chinese Academy of Medical Sciences & Peking Union Medical College, Beijing, China
| | - Hongwei Li
- Institute of Microcirculation, Chinese Academy of Medical Sciences & Peking Union Medical College, Beijing, China
| | - Jianqun Han
- Institute of Microcirculation, Chinese Academy of Medical Sciences & Peking Union Medical College, Beijing, China
| | - Ailing Li
- Institute of Microcirculation, Chinese Academy of Medical Sciences & Peking Union Medical College, Beijing, China
| | - Wenbao Lu
- Institute of Microcirculation, Chinese Academy of Medical Sciences & Peking Union Medical College, Beijing, China
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13
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Avilés-Pagán EE, Hara M, Orr-Weaver TL. The GNU subunit of PNG kinase, the developmental regulator of mRNA translation, binds BIC-C to localize to RNP granules. eLife 2021; 10:67294. [PMID: 34250903 PMCID: PMC8313231 DOI: 10.7554/elife.67294] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/12/2021] [Accepted: 07/09/2021] [Indexed: 11/15/2022] Open
Abstract
Control of mRNA translation is a key mechanism by which the differentiated oocyte transitions to a totipotent embryo. In Drosophila, the PNG kinase complex regulates maternal mRNA translation at the oocyte-to-embryo transition. We previously showed that the GNU activating subunit is crucial in regulating PNG and timing its activity to the window between egg activation and early embryogenesis (Hara et al., 2017). In this study, we find associations between GNU and proteins of RNP granules and demonstrate that GNU localizes to cytoplasmic RNP granules in the mature oocyte, identifying GNU as a new component of a subset of RNP granules. Furthermore, we define roles for the domains of GNU. Interactions between GNU and the granule component BIC-C reveal potential conserved functions for translational regulation in metazoan development. We propose that by binding to BIC-C, upon egg activation GNU brings PNG to its initial targets, translational repressors in RNP granules.
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Affiliation(s)
- Emir E Avilés-Pagán
- Department of Biology, MIT, Cambridge, United States.,Whitehead Institute for Biomedical Research, Cambridge, United States
| | - Masatoshi Hara
- Whitehead Institute for Biomedical Research, Cambridge, United States
| | - Terry L Orr-Weaver
- Department of Biology, MIT, Cambridge, United States.,Whitehead Institute for Biomedical Research, Cambridge, United States
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14
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Grützner J, Billenkamp F, Spanka DT, Rick T, Monzon V, Förstner KU, Klug G. The small DUF1127 protein CcaF1 from Rhodobacter sphaeroides is an RNA-binding protein involved in sRNA maturation and RNA turnover. Nucleic Acids Res 2021; 49:3003-3019. [PMID: 33706375 PMCID: PMC8034643 DOI: 10.1093/nar/gkab146] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/17/2020] [Revised: 02/10/2021] [Accepted: 02/26/2021] [Indexed: 12/16/2022] Open
Abstract
Many different protein domains are conserved among numerous species, but their function remains obscure. Proteins with DUF1127 domains number >17 000 in current databases, but a biological function has not yet been assigned to any of them. They are mostly found in alpha- and gammaproteobacteria, some of them plant and animal pathogens, symbionts or species used in industrial applications. Bioinformatic analyses revealed similarity of the DUF1127 domain of bacterial proteins to the RNA binding domain of eukaryotic Smaug proteins that are involved in RNA turnover and have a role in development from Drosophila to mammals. This study demonstrates that the 71 amino acid DUF1127 protein CcaF1 from the alphaproteobacterium Rhodobacter sphaeroides participates in maturation of the CcsR sRNAs that are processed from the 3' UTR of the ccaF mRNA and have a role in the oxidative stress defense. CcaF1 binds to many cellular RNAs of different type, several mRNAs with a function in cysteine / methionine / sulfur metabolism. It affects the stability of the CcsR RNAs and other non-coding RNAs and mRNAs. Thus, the widely distributed DUF1127 domain can mediate RNA-binding, affect stability of its binding partners and consequently modulate the bacterial transcriptome, thereby influencing different physiological processes.
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Affiliation(s)
- Julian Grützner
- Institute of Microbiology and Molecular Biology, Justus Liebig University Giessen, IFZ, Heinrich-Buff-Ring 26–32, D-35292 Giessen, Germany
| | - Fabian Billenkamp
- Institute of Microbiology and Molecular Biology, Justus Liebig University Giessen, IFZ, Heinrich-Buff-Ring 26–32, D-35292 Giessen, Germany
- Institute of Animal Nutrition, Friedrich Loeffler Institute, Bundesalle 37, D-38116 Braunschweig, Germany
| | - Daniel-Timon Spanka
- Institute of Microbiology and Molecular Biology, Justus Liebig University Giessen, IFZ, Heinrich-Buff-Ring 26–32, D-35292 Giessen, Germany
| | - Tim Rick
- Institute of Microbiology and Molecular Biology, Justus Liebig University Giessen, IFZ, Heinrich-Buff-Ring 26–32, D-35292 Giessen, Germany
| | | | - Konrad U Förstner
- ZB MED-Information Center of Life Science, Germany
- Institute of Information Science, TH Köln, University of Applied Science, Gustav-Heinemann-Ufer 54, D-50968 Köln, Cologne, Germany
| | - Gabriele Klug
- Institute of Microbiology and Molecular Biology, Justus Liebig University Giessen, IFZ, Heinrich-Buff-Ring 26–32, D-35292 Giessen, Germany
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15
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Caudron-Herger M, Jansen RE, Wassmer E, Diederichs S. RBP2GO: a comprehensive pan-species database on RNA-binding proteins, their interactions and functions. Nucleic Acids Res 2021; 49:D425-D436. [PMID: 33196814 PMCID: PMC7778890 DOI: 10.1093/nar/gkaa1040] [Citation(s) in RCA: 44] [Impact Index Per Article: 14.7] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/14/2020] [Revised: 10/01/2020] [Accepted: 10/28/2020] [Indexed: 02/06/2023] Open
Abstract
RNA-protein complexes have emerged as central players in numerous key cellular processes with significant relevance in health and disease. To further deepen our knowledge of RNA-binding proteins (RBPs), multiple proteome-wide strategies have been developed to identify RBPs in different species leading to a large number of studies contributing experimentally identified as well as predicted RBP candidate catalogs. However, the rapid evolution of the field led to an accumulation of isolated datasets, hampering the access and comparison of their valuable content. Moreover, tools to link RBPs to cellular pathways and functions were lacking. Here, to facilitate the efficient screening of the RBP resources, we provide RBP2GO (https://RBP2GO.DKFZ.de), a comprehensive database of all currently available proteome-wide datasets for RBPs across 13 species from 53 studies including 105 datasets identifying altogether 22 552 RBP candidates. These are combined with the information on RBP interaction partners and on the related biological processes, molecular functions and cellular compartments. RBP2GO offers a user-friendly web interface with an RBP scoring system and powerful advanced search tools allowing forward and reverse searches connecting functions and RBPs to stimulate new research directions.
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Affiliation(s)
- Maiwen Caudron-Herger
- Division of RNA Biology & Cancer, German Cancer Research Center (DKFZ), 69120 Heidelberg, Germany
| | - Ralf E Jansen
- Division of RNA Biology & Cancer, German Cancer Research Center (DKFZ), 69120 Heidelberg, Germany
| | - Elsa Wassmer
- Division of RNA Biology & Cancer, German Cancer Research Center (DKFZ), 69120 Heidelberg, Germany
| | - Sven Diederichs
- Division of RNA Biology & Cancer, German Cancer Research Center (DKFZ), 69120 Heidelberg, Germany.,Division of Cancer Research, Department of Thoracic Surgery, Medical Center - University of Freiburg, Faculty of Medicine, University of Freiburg, German Cancer Consortium (DKTK) - Partner Site Freiburg, 79106 Freiburg, Germany
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16
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Tamura K, Chiu YW, Shiohara A, Hori Y, Tomita T. EphA4 regulates Aβ production via BACE1 expression in neurons. FASEB J 2020; 34:16383-16396. [PMID: 33090569 DOI: 10.1096/fj.202001510r] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/15/2020] [Revised: 08/28/2020] [Accepted: 10/02/2020] [Indexed: 01/05/2023]
Abstract
Several lines of evidence suggest that the aggregation and deposition of amyloid-β peptide (Aβ) initiate the pathology of Alzheimer's disease (AD). Recently, a genome-wide association study demonstrated that a single-nucleotide polymorphism proximal to the EPHA4 gene, which encodes a receptor tyrosine kinase, is associated with AD risk. However, the molecular mechanism of EphA4 in the pathogenesis of AD, particularly in Aβ production, remains unknown. Here, we performed several pharmacological and biological experiments both in vitro and in vivo and demonstrated that EphA4 is responsible for the regulation of Aβ production. Pharmacological inhibition of EphA4 signaling and knockdown of Epha4 led to increased Aβ levels accompanied by increased expression of β-site APP cleaving enzyme 1 (BACE1), which is an enzyme responsible for Aβ production. Moreover, EPHA4 overexpression and activation of EphA4 signaling via ephrin ligands decreased Aβ levels. In particular, the sterile-alpha motif domain of EphA4 was necessary for the regulation of Aβ production. Finally, EPHA4 mRNA levels were significantly reduced in the brains of AD patients, and negatively correlated with BACE1 mRNA levels. Our results indicate a novel mechanism of Aβ regulation by EphA4, which is involved in AD pathogenesis.
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Affiliation(s)
- Kensuke Tamura
- Laboratory of Neuropathology and Neuroscience, Graduate School of Pharmaceutical Sciences, The University of Tokyo, Tokyo, Japan
| | - Yung-Wen Chiu
- Laboratory of Neuropathology and Neuroscience, Graduate School of Pharmaceutical Sciences, The University of Tokyo, Tokyo, Japan
| | - Azusa Shiohara
- Laboratory of Neuropathology and Neuroscience, Graduate School of Pharmaceutical Sciences, The University of Tokyo, Tokyo, Japan
| | - Yukiko Hori
- Laboratory of Neuropathology and Neuroscience, Graduate School of Pharmaceutical Sciences, The University of Tokyo, Tokyo, Japan
| | - Taisuke Tomita
- Laboratory of Neuropathology and Neuroscience, Graduate School of Pharmaceutical Sciences, The University of Tokyo, Tokyo, Japan
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17
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Viral hijacking of the TENT4-ZCCHC14 complex protects viral RNAs via mixed tailing. Nat Struct Mol Biol 2020; 27:581-588. [PMID: 32451488 DOI: 10.1038/s41594-020-0427-3] [Citation(s) in RCA: 39] [Impact Index Per Article: 9.8] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/18/2019] [Accepted: 04/03/2020] [Indexed: 12/20/2022]
Abstract
TENT4 enzymes generate 'mixed tails' of diverse nucleotides at 3' ends of RNAs via nontemplated nucleotide addition to protect messenger RNAs from deadenylation. Here we discover extensive mixed tailing in transcripts of hepatitis B virus (HBV) and human cytomegalovirus (HCMV), generated via a similar mechanism exploiting the TENT4-ZCCHC14 complex. TAIL-seq on HBV and HCMV RNAs revealed that TENT4A and TENT4B are responsible for mixed tailing and protection of viral poly(A) tails. We find that the HBV post-transcriptional regulatory element (PRE), specifically the CNGGN-type pentaloop, is critical for TENT4-dependent regulation. HCMV uses a similar pentaloop, an interesting example of convergent evolution. This pentaloop is recognized by the sterile alpha motif domain-containing ZCCHC14 protein, which in turn recruits TENT4. Overall, our study reveals the mechanism of action of PRE, which has been widely used to enhance gene expression, and identifies the TENT4-ZCCHC14 complex as a potential target for antiviral therapeutics.
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18
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Bruzzone L, Argüelles C, Sanial M, Miled S, Alvisi G, Gonçalves-Antunes M, Qasrawi F, Holmgren RA, Smibert CA, Lipshitz HD, Boccaccio GL, Plessis A, Bécam I. Regulation of the RNA-binding protein Smaug by the GPCR Smoothened via the kinase Fused. EMBO Rep 2020; 21:e48425. [PMID: 32383557 DOI: 10.15252/embr.201948425] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/17/2019] [Revised: 03/17/2020] [Accepted: 04/14/2020] [Indexed: 12/13/2022] Open
Abstract
From fly to mammals, the Smaug/Samd4 family of prion-like RNA-binding proteins control gene expression by destabilizing and/or repressing the translation of numerous target transcripts. However, the regulation of its activity remains poorly understood. We show that Smaug's protein levels and mRNA repressive activity are downregulated by Hedgehog signaling in tissue culture cells. These effects rely on the interaction of Smaug with the G-protein coupled receptor Smoothened, which promotes the phosphorylation of Smaug by recruiting the kinase Fused. The activation of Fused and its binding to Smaug are sufficient to suppress its ability to form cytosolic bodies and to antagonize its negative effects on endogenous targets. Importantly, we demonstrate in vivo that HH reduces the levels of smaug mRNA and increases the level of several mRNAs downregulated by Smaug. Finally, we show that Smaug acts as a positive regulator of Hedgehog signaling during wing morphogenesis. These data constitute the first evidence for a post-translational regulation of Smaug and reveal that the fate of several mRNAs bound to Smaug is modulated by a major signaling pathway.
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Affiliation(s)
- Lucia Bruzzone
- CNRS, Institut Jacques Monod, Université de Paris, Paris, France
| | | | - Matthieu Sanial
- CNRS, Institut Jacques Monod, Université de Paris, Paris, France
| | - Samia Miled
- CNRS, Institut Jacques Monod, Université de Paris, Paris, France
| | - Giorgia Alvisi
- CNRS, Institut Jacques Monod, Université de Paris, Paris, France
| | | | - Fairouz Qasrawi
- CNRS, Institut Jacques Monod, Université de Paris, Paris, France
| | - Robert A Holmgren
- Department of Mol. Biosci., Northwestern University, Evanston, IL, USA
| | - Craig A Smibert
- Department of Biochemistry, University of Toronto, Toronto, ON, Canada.,Department of Molecular Genetics, University of Toronto, Toronto, ON, Canada
| | - Howard D Lipshitz
- Department of Molecular Genetics, University of Toronto, Toronto, ON, Canada
| | - Graciela L Boccaccio
- Fundación Instituto Leloir, Instituto de Investigaciones Bioquímicas Buenos Aires-Consejo Nacional de Investigaciones Científicas y Tecnológicas, Facultad de Ciencias Exactas y Naturales, University of Buenos Aires, Buenos Aires, Argentina
| | - Anne Plessis
- CNRS, Institut Jacques Monod, Université de Paris, Paris, France
| | - Isabelle Bécam
- CNRS, Institut Jacques Monod, Université de Paris, Paris, France
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19
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Palm D, Streit D, Shanmugam T, Weis BL, Ruprecht M, Simm S, Schleiff E. Plant-specific ribosome biogenesis factors in Arabidopsis thaliana with essential function in rRNA processing. Nucleic Acids Res 2019; 47:1880-1895. [PMID: 30576513 PMCID: PMC6393314 DOI: 10.1093/nar/gky1261] [Citation(s) in RCA: 36] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/22/2018] [Revised: 12/04/2018] [Accepted: 12/18/2018] [Indexed: 12/22/2022] Open
Abstract
rRNA processing and assembly of ribosomal proteins during maturation of ribosomes involve many ribosome biogenesis factors (RBFs). Recent studies identified differences in the set of RBFs in humans and yeast, and the existence of plant-specific RBFs has been proposed as well. To identify such plant-specific RBFs, we characterized T-DNA insertion mutants of 15 Arabidopsis thaliana genes encoding nuclear proteins with nucleotide binding properties that are not orthologues to yeast or human RBFs. Mutants of nine genes show an altered rRNA processing ranging from inhibition of initial 35S pre-rRNA cleavage to final maturation events like the 6S pre-rRNA processing. These phenotypes led to their annotation as 'involved in rRNA processing' - IRP. The irp mutants are either lethal or show developmental and stress related phenotypes. We identified IRPs for maturation of the plant-specific precursor 5'-5.8S and one affecting the pathway with ITS2 first cleavage of the 35S pre-rRNA transcript. Moreover, we realized that 5'-5.8S processing is essential, while a mutant causing 6S accumulation shows only a weak phenotype. Thus, we demonstrate the importance of the maturation of the plant-specific precursor 5'-5.8S for plant development as well as the occurrence of an ITS2 first cleavage pathway in fast dividing tissues.
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Affiliation(s)
- Denise Palm
- Institute for Molecular Biosciences, Goethe University Frankfurt, Max von Laue Str. 9, D-60438 Frankfurt, Germany
| | - Deniz Streit
- Institute for Molecular Biosciences, Goethe University Frankfurt, Max von Laue Str. 9, D-60438 Frankfurt, Germany
| | - Thiruvenkadam Shanmugam
- Institute for Molecular Biosciences, Goethe University Frankfurt, Max von Laue Str. 9, D-60438 Frankfurt, Germany
| | - Benjamin L Weis
- Institute for Molecular Biosciences, Goethe University Frankfurt, Max von Laue Str. 9, D-60438 Frankfurt, Germany
| | - Maike Ruprecht
- Institute for Molecular Biosciences, Goethe University Frankfurt, Max von Laue Str. 9, D-60438 Frankfurt, Germany
| | - Stefan Simm
- Institute for Molecular Biosciences, Goethe University Frankfurt, Max von Laue Str. 9, D-60438 Frankfurt, Germany
- Frankfurt Institute for Advanced Studies, D-60438 Frankfurt, Germany
| | - Enrico Schleiff
- Institute for Molecular Biosciences, Goethe University Frankfurt, Max von Laue Str. 9, D-60438 Frankfurt, Germany
- Frankfurt Institute for Advanced Studies, D-60438 Frankfurt, Germany
- Buchmann Institute for Molecular Life Sciences, Goethe University Frankfurt, D-60438 Frankfurt, Germany
- To whom correspondence should be addressed. Tel: +49 69 798 29285; Fax: +49 69 798 29286;
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20
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Kukuk L, Dingley AJ, Granzin J, Nagel-Steger L, Thiagarajan-Rosenkranz P, Ciupka D, Hänel K, Batra-Safferling R, Pacheco V, Stoldt M, Pfeffer K, Beer-Hammer S, Willbold D, Koenig BW. Structure of the SLy1 SAM homodimer reveals a new interface for SAM domain self-association. Sci Rep 2019; 9:54. [PMID: 30631134 PMCID: PMC6328559 DOI: 10.1038/s41598-018-37185-3] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2018] [Accepted: 11/30/2018] [Indexed: 11/08/2022] Open
Abstract
Sterile alpha motif (SAM) domains are protein interaction modules that are involved in a diverse range of biological functions such as transcriptional and translational regulation, cellular signalling, and regulation of developmental processes. SH3 domain-containing protein expressed in lymphocytes 1 (SLy1) is involved in immune regulation and contains a SAM domain of unknown function. In this report, the structure of the SLy1 SAM domain was solved and revealed that this SAM domain forms a symmetric homodimer through a novel interface. The interface consists primarily of the two long C-terminal helices, α5 and α5', of the domains packing against each other. The dimerization is characterized by a dissociation constant in the lower micromolar range. A SLy1 SAM domain construct with an extended N-terminus containing five additional amino acids of the SLy1 sequence further increases the stability of the homodimer, making the SLy1 SAM dimer two orders of magnitude more stable than previously studied SAM homodimers, suggesting that the SLy1 SAM dimerization is of functional significance. The SLy1 SAM homodimer contains an exposed mid-loop surface on each monomer, which may provide a scaffold for mediating interactions with other SAM domain-containing proteins via a typical mid-loop-end-helix interface.
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Affiliation(s)
- Laura Kukuk
- Institute of Complex Systems, Strukturbiochemie (ICS-6), Forschungszentrum Jülich, 52425, Jülich, Germany
- Institut für Physikalische Biologie, Heinrich-Heine-Universität Düsseldorf, Universitätsstraße 1, 40225, Düsseldorf, Germany
| | - Andrew J Dingley
- Institute of Complex Systems, Strukturbiochemie (ICS-6), Forschungszentrum Jülich, 52425, Jülich, Germany
- Institut für Physikalische Biologie, Heinrich-Heine-Universität Düsseldorf, Universitätsstraße 1, 40225, Düsseldorf, Germany
| | - Joachim Granzin
- Institute of Complex Systems, Strukturbiochemie (ICS-6), Forschungszentrum Jülich, 52425, Jülich, Germany
| | - Luitgard Nagel-Steger
- Institute of Complex Systems, Strukturbiochemie (ICS-6), Forschungszentrum Jülich, 52425, Jülich, Germany
- Institut für Physikalische Biologie, Heinrich-Heine-Universität Düsseldorf, Universitätsstraße 1, 40225, Düsseldorf, Germany
| | - Pallavi Thiagarajan-Rosenkranz
- Institute of Complex Systems, Strukturbiochemie (ICS-6), Forschungszentrum Jülich, 52425, Jülich, Germany
- Institut für Physikalische Biologie, Heinrich-Heine-Universität Düsseldorf, Universitätsstraße 1, 40225, Düsseldorf, Germany
| | - Daniel Ciupka
- Institut für Physikalische Biologie, Heinrich-Heine-Universität Düsseldorf, Universitätsstraße 1, 40225, Düsseldorf, Germany
| | - Karen Hänel
- Institute of Complex Systems, Strukturbiochemie (ICS-6), Forschungszentrum Jülich, 52425, Jülich, Germany
| | - Renu Batra-Safferling
- Institute of Complex Systems, Strukturbiochemie (ICS-6), Forschungszentrum Jülich, 52425, Jülich, Germany
| | - Victor Pacheco
- Institute of Complex Systems, Strukturbiochemie (ICS-6), Forschungszentrum Jülich, 52425, Jülich, Germany
- Institut für Makromolekulare Chemie, Albert-Ludwigs-Universität Freiburg, Stefan-Meier-Straße 31, 79104, Freiburg, Germany
| | - Matthias Stoldt
- Institut für Physikalische Biologie, Heinrich-Heine-Universität Düsseldorf, Universitätsstraße 1, 40225, Düsseldorf, Germany
| | - Klaus Pfeffer
- Institut für Medizinische Mikrobiologie und Krankenhaushygiene, Heinrich-Heine-Universität Düsseldorf, Universitätsstraße 1, 40225, Düsseldorf, Germany
| | - Sandra Beer-Hammer
- Institut für Medizinische Mikrobiologie und Krankenhaushygiene, Heinrich-Heine-Universität Düsseldorf, Universitätsstraße 1, 40225, Düsseldorf, Germany
- Institut für Experimentelle und Klinische Pharmakologie und Toxikologie, und Interfakultäres Zentrum für Pharmakogenomik und Arzneimittelforschung (ICePhA), Eberhard-Karls-Universität Tübingen, Wilhelmstraße 56, 72074, Tübingen, Germany
| | - Dieter Willbold
- Institute of Complex Systems, Strukturbiochemie (ICS-6), Forschungszentrum Jülich, 52425, Jülich, Germany.
- Institut für Physikalische Biologie, Heinrich-Heine-Universität Düsseldorf, Universitätsstraße 1, 40225, Düsseldorf, Germany.
| | - Bernd W Koenig
- Institute of Complex Systems, Strukturbiochemie (ICS-6), Forschungszentrum Jülich, 52425, Jülich, Germany.
- Institut für Physikalische Biologie, Heinrich-Heine-Universität Düsseldorf, Universitätsstraße 1, 40225, Düsseldorf, Germany.
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21
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Nørgaard S, Deng S, Cao W, Pocock R. Distinct CED-10/Rac1 domains confer context-specific functions in development. PLoS Genet 2018; 14:e1007670. [PMID: 30265669 PMCID: PMC6179291 DOI: 10.1371/journal.pgen.1007670] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/11/2018] [Revised: 10/10/2018] [Accepted: 08/30/2018] [Indexed: 11/18/2022] Open
Abstract
Rac GTPases act as master switches to coordinate multiple interweaved signaling pathways. A major function for Rac GTPases is to control neurite development by influencing downstream effector molecules and pathways. In Caenorhabditis elegans, the Rac proteins CED-10, RAC-2 and MIG-2 act in parallel to control axon outgrowth and guidance. Here, we have identified a single glycine residue in the CED-10/Rac1 Switch 1 region that confers a non-redundant function in axon outgrowth but not guidance. Mutation of this glycine to glutamic acid (G30E) reduces GTP binding and inhibits axon outgrowth but does not affect other canonical CED-10 functions. This demonstrates previously unappreciated domain-specific functions within the CED-10 protein. Further, we reveal that when CED-10 function is diminished, the adaptor protein NAB-1 (Neurabin) and its interacting partner SYD-1 (Rho-GAP-like protein) can act as inhibitors of axon outgrowth. Together, we reveal that specific domains and residues within Rac GTPases can confer context-dependent functions during animal development. Brain development requires that neurite outgrowth and guidance are precisely regulated. Previous studies have shown that molecular switch proteins called Rac GTPases perform redundant functions in controlling neurite development. Using a pair of bilateral neurons in the nematode Caenorhabditis elegans to model neurite development, we found that a single amino acid in a conserved domain of the Rac GTPase CED-10 is crucial for controlling neurite outgrowth in a partially non-redundant manner. Further, we revealed that lesions in discrete domains in the CED-10 protein lead to distinct developmental defects. Therefore, our in vivo study proposes that regulation of distinct signalling pathways through Rac GTPase protein domains can drive different developmental outcomes.
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Affiliation(s)
- Steffen Nørgaard
- Development and Stem Cells Program, Monash Biomedicine Discovery Institute and Department of Anatomy and Developmental Biology, Monash University, Melbourne, Victoria, Australia
- Biotech Research and Innovation Centre, University of Copenhagen, Copenhagen, Denmark
| | - Shuer Deng
- Development and Stem Cells Program, Monash Biomedicine Discovery Institute and Department of Anatomy and Developmental Biology, Monash University, Melbourne, Victoria, Australia
| | - Wei Cao
- Development and Stem Cells Program, Monash Biomedicine Discovery Institute and Department of Anatomy and Developmental Biology, Monash University, Melbourne, Victoria, Australia
| | - Roger Pocock
- Development and Stem Cells Program, Monash Biomedicine Discovery Institute and Department of Anatomy and Developmental Biology, Monash University, Melbourne, Victoria, Australia
- Biotech Research and Innovation Centre, University of Copenhagen, Copenhagen, Denmark
- * E-mail:
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22
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Denay G, Vachon G, Dumas R, Zubieta C, Parcy F. Plant SAM-Domain Proteins Start to Reveal Their Roles. TRENDS IN PLANT SCIENCE 2017; 22:718-725. [PMID: 28668510 DOI: 10.1016/j.tplants.2017.06.006] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/21/2017] [Revised: 06/02/2017] [Accepted: 06/05/2017] [Indexed: 06/07/2023]
Abstract
Proteins often act in complexes assembled via protein-protein interaction domains. The sterile alpha motif (SAM) domain is one of the most prominent interaction domains in animals and is present in proteins of diverse functions. This domain allows head-to-tail closed oligomerisation or polymer formation resulting in homo- and/or heterocomplexes that have been shown to be important for proper protein localisation and function. In plants this domain is also present but has been poorly studied except for recent studies on the LEAFY floral regulator and the tRNA import component (TRIC)1/2 proteins. Here we catalogue SAM domain-containing proteins from arabidopsis (Arabidopsis thaliana), compare plant and other eukaryotic SAM domains, and perform homology modelling to probe plant SAM domain interaction capabilities.
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Affiliation(s)
- Grégoire Denay
- LPCV, CEA, CNRS, INRA, Université Grenoble-Alpes, BIG, 38000 Grenoble, France; Institute for Developmental Genetics, Heinrich-Heine-Universität Düsseldorf, Universitätstraße, D-40225 Düsseldorf, Germany
| | - Gilles Vachon
- LPCV, CEA, CNRS, INRA, Université Grenoble-Alpes, BIG, 38000 Grenoble, France
| | - Renaud Dumas
- LPCV, CEA, CNRS, INRA, Université Grenoble-Alpes, BIG, 38000 Grenoble, France
| | - Chloe Zubieta
- LPCV, CEA, CNRS, INRA, Université Grenoble-Alpes, BIG, 38000 Grenoble, France
| | - François Parcy
- LPCV, CEA, CNRS, INRA, Université Grenoble-Alpes, BIG, 38000 Grenoble, France.
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23
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Abstract
Asymmetric localization of mRNAs is a widespread gene regulatory mechanism that is crucial for many cellular processes. The localization of a transcript involves multiple steps and requires several protein factors to mediate transport, anchoring and translational repression of the mRNA. Specific recognition of the localizing transcript is a key step that depends on linear or structured localization signals, which are bound by RNA-binding proteins. Genetic studies have identified many components involved in mRNA localization. However, mechanistic aspects of the pathway are still poorly understood. Here we provide an overview of structural studies that contributed to our understanding of the mechanisms underlying mRNA localization, highlighting open questions and future challenges.
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Affiliation(s)
| | - Fulvia Bono
- a Max Planck Institute for Developmental Biology , Tübingen , Germany
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24
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Cabukusta B, Kol M, Kneller L, Hilderink A, Bickert A, Mina JGM, Korneev S, Holthuis JCM. ER residency of the ceramide phosphoethanolamine synthase SMSr relies on homotypic oligomerization mediated by its SAM domain. Sci Rep 2017; 7:41290. [PMID: 28120887 PMCID: PMC5264588 DOI: 10.1038/srep41290] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/22/2016] [Accepted: 12/19/2016] [Indexed: 12/12/2022] Open
Abstract
SMSr/SAMD8 is an ER-resident ceramide phosphoethanolamine synthase with a critical role in controlling ER ceramides and suppressing ceramide-induced apoptosis in cultured cells. SMSr-mediated ceramide homeostasis relies on the enzyme's catalytic activity as well as on its N-terminal sterile α-motif or SAM domain. Here we report that SMSr-SAM is structurally and functionally related to the SAM domain of diacylglycerol kinase DGKδ, a central regulator of lipid signaling at the plasma membrane. Native gel electrophoresis indicates that both SAM domains form homotypic oligomers. Chemical crosslinking studies show that SMSr self-associates into ER-resident trimers and hexamers that resemble the helical oligomers formed by DGKδ-SAM. Residues critical for DGKδ-SAM oligomerization are conserved in SMSr-SAM and their substitution causes a dissociation of SMSr oligomers as well as a partial redistribution of the enzyme to the Golgi. Conversely, treatment of cells with curcumin, a drug disrupting ceramide and Ca2+ homeostasis in the ER, stabilizes SMSr oligomers and promotes retention of the enzyme in the ER. Our data provide first demonstration of a multi-pass membrane protein that undergoes homotypic oligomerization via its SAM domain and indicate that SAM-mediated self-assembly of SMSr is required for efficient retention of the enzyme in the ER.
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Affiliation(s)
- Birol Cabukusta
- Molecular Cell Biology Division, Faculty of Biology/Chemistry, University of Osnabrück, 49076 Osnabrück, Germany
| | - Matthijs Kol
- Molecular Cell Biology Division, Faculty of Biology/Chemistry, University of Osnabrück, 49076 Osnabrück, Germany
| | - Laura Kneller
- Molecular Cell Biology Division, Faculty of Biology/Chemistry, University of Osnabrück, 49076 Osnabrück, Germany
| | - Angelika Hilderink
- Molecular Cell Biology Division, Faculty of Biology/Chemistry, University of Osnabrück, 49076 Osnabrück, Germany
| | - Andreas Bickert
- Molecular Genetics, Life and Medical Sciences Institute, University of Bonn, 53115 Bonn, Germany
| | - John G. M. Mina
- Molecular Cell Biology Division, Faculty of Biology/Chemistry, University of Osnabrück, 49076 Osnabrück, Germany
| | - Sergei Korneev
- Molecular Cell Biology Division, Faculty of Biology/Chemistry, University of Osnabrück, 49076 Osnabrück, Germany
| | - Joost C. M. Holthuis
- Molecular Cell Biology Division, Faculty of Biology/Chemistry, University of Osnabrück, 49076 Osnabrück, Germany
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25
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Piggin CL, Roden DL, Gallego-Ortega D, Lee HJ, Oakes SR, Ormandy CJ. ELF5 isoform expression is tissue-specific and significantly altered in cancer. Breast Cancer Res 2016; 18:4. [PMID: 26738740 PMCID: PMC4704400 DOI: 10.1186/s13058-015-0666-0] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/06/2015] [Accepted: 12/16/2015] [Indexed: 12/14/2022] Open
Abstract
Background E74-like factor 5 (ELF5) is an epithelial-specific member of the E26 transforming sequence (ETS) transcription factor family and a critical regulator of cell fate in the placenta, pulmonary bronchi, and milk-producing alveoli of the mammary gland. ELF5 also plays key roles in malignancy, particularly in basal-like and endocrine-resistant forms of breast cancer. Almost all genes undergo alternative transcription or splicing, which increases the diversity of protein structure and function. Although ELF5 has multiple isoforms, this has not been considered in previous studies of ELF5 function. Methods RNA-sequencing data for 6757 samples from The Cancer Genome Atlas were analyzed to characterize ELF5 isoform expression in multiple normal tissues and cancers. Extensive in vitro analysis of ELF5 isoforms, including a 116-gene quantitative polymerase chain reaction panel, was performed in breast cancer cell lines. Results ELF5 isoform expression was found to be tissue-specific due to alternative promoter use but altered in multiple cancer types. The normal breast expressed one main isoform, while in breast cancer there were subtype-specific alterations in expression. Expression of other ETS factors was also significantly altered in breast cancer, with the basal-like subtype demonstrating a distinct ETS expression profile. In vitro inducible expression of the full-length isoforms 1 and 2, as well as isoform 3 (lacking the Pointed domain) had similar phenotypic and transcriptional effects. Conclusions Alternative promoter use, conferring differential regulatory responses, is the main mechanism governing ELF5 action rather than differential transcriptional activity of the isoforms. This understanding of expression and function at the isoform level is a vital first step in realizing the potential of transcription factors such as ELF5 as prognostic markers or therapeutic targets in cancer. Electronic supplementary material The online version of this article (doi:10.1186/s13058-015-0666-0) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Catherine L Piggin
- Cancer Division, Garvan Institute of Medical Research/The Kinghorn Cancer Centre, Sydney, NSW, 2010, Australia.
| | - Daniel L Roden
- Cancer Division, Garvan Institute of Medical Research/The Kinghorn Cancer Centre, Sydney, NSW, 2010, Australia.
| | - David Gallego-Ortega
- Cancer Division, Garvan Institute of Medical Research/The Kinghorn Cancer Centre, Sydney, NSW, 2010, Australia.
| | - Heather J Lee
- Cancer Division, Garvan Institute of Medical Research/The Kinghorn Cancer Centre, Sydney, NSW, 2010, Australia. .,Babraham Institute, Cambridge, CB22 3AT, UK.
| | - Samantha R Oakes
- Cancer Division, Garvan Institute of Medical Research/The Kinghorn Cancer Centre, Sydney, NSW, 2010, Australia.
| | - Christopher J Ormandy
- Cancer Division, Garvan Institute of Medical Research/The Kinghorn Cancer Centre, Sydney, NSW, 2010, Australia.
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26
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Anks3 interacts with nephronophthisis proteins and is required for normal renal development. Kidney Int 2015; 87:1191-200. [DOI: 10.1038/ki.2015.17] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/24/2014] [Revised: 11/10/2014] [Accepted: 12/05/2014] [Indexed: 12/19/2022]
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Chartier A, Klein P, Pierson S, Barbezier N, Gidaro T, Casas F, Carberry S, Dowling P, Maynadier L, Bellec M, Oloko M, Jardel C, Moritz B, Dickson G, Mouly V, Ohlendieck K, Butler-Browne G, Trollet C, Simonelig M. Mitochondrial dysfunction reveals the role of mRNA poly(A) tail regulation in oculopharyngeal muscular dystrophy pathogenesis. PLoS Genet 2015; 11:e1005092. [PMID: 25816335 PMCID: PMC4376527 DOI: 10.1371/journal.pgen.1005092] [Citation(s) in RCA: 41] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/17/2014] [Accepted: 02/23/2015] [Indexed: 01/25/2023] Open
Abstract
Oculopharyngeal muscular dystrophy (OPMD), a late-onset disorder characterized by progressive degeneration of specific muscles, results from the extension of a polyalanine tract in poly(A) binding protein nuclear 1 (PABPN1). While the roles of PABPN1 in nuclear polyadenylation and regulation of alternative poly(A) site choice are established, the molecular mechanisms behind OPMD remain undetermined. Here, we show, using Drosophila and mouse models, that OPMD pathogenesis depends on affected poly(A) tail lengths of specific mRNAs. We identify a set of mRNAs encoding mitochondrial proteins that are down-regulated starting at the earliest stages of OPMD progression. The down-regulation of these mRNAs correlates with their shortened poly(A) tails and partial rescue of their levels when deadenylation is genetically reduced improves muscle function. Genetic analysis of candidate genes encoding RNA binding proteins using the Drosophila OPMD model uncovers a potential role of a number of them. We focus on the deadenylation regulator Smaug and show that it is expressed in adult muscles and specifically binds to the down-regulated mRNAs. In addition, the first step of the cleavage and polyadenylation reaction, mRNA cleavage, is affected in muscles expressing alanine-expanded PABPN1. We propose that impaired cleavage during nuclear cleavage/polyadenylation is an early defect in OPMD. This defect followed by active deadenylation of specific mRNAs, involving Smaug and the CCR4-NOT deadenylation complex, leads to their destabilization and mitochondrial dysfunction. These results broaden our understanding of the role of mRNA regulation in pathologies and might help to understand the molecular mechanisms underlying neurodegenerative disorders that involve mitochondrial dysfunction. Oculopharyngeal muscular dystrophy is a genetic disease characterized by progressive degeneration of specific muscles, leading to ptosis (eyelid drooping), dysphagia (swallowing difficulties) and proximal limb weakness. The disease results from mutations in a nuclear protein called poly(A) binding protein nuclear 1 that is involved in polyadenylation of messenger RNAs (mRNAs) and poly(A) site selection. To address the molecular mechanisms involved in the disease, we have used two animal models (Drosophila and mouse) that recapitulate the features of this disorder. We show that oculopharyngeal muscular dystrophy pathogenesis depends on defects in poly(A) tail length regulation of specific mRNAs. Because poly(A) tails play an essential role in mRNA stability, these defects result in accelerated decay of these mRNAs. The affected mRNAs encode mitochondrial proteins, and mitochondrial activity is impaired in diseased muscles. These findings have important implications for the development of potential therapies for oculopharyngeal muscular dystrophy, and might be relevant to decipher the molecular mechanisms underlying other disorders that involve mitochondrial dysfunction.
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Affiliation(s)
- Aymeric Chartier
- mRNA Regulation and Development, Institut de Génétique Humaine, CNRS UPR1142, Montpellier, France
| | - Pierre Klein
- Sorbonne Universités, UPMC Univ Paris 06, UM76, INSERM UMRS974, CNRS FRE3617, Center for Research in Myology, Paris, France
| | - Stéphanie Pierson
- mRNA Regulation and Development, Institut de Génétique Humaine, CNRS UPR1142, Montpellier, France
| | - Nicolas Barbezier
- mRNA Regulation and Development, Institut de Génétique Humaine, CNRS UPR1142, Montpellier, France
| | - Teresa Gidaro
- Sorbonne Universités, UPMC Univ Paris 06, UM76, INSERM UMRS974, CNRS FRE3617, Center for Research in Myology, Paris, France
| | - François Casas
- INRA, UMR 866 Différenciation cellulaire et croissance, Montpellier, France
| | - Steven Carberry
- Department of Biology, National University of Ireland, Maynooth, Ireland
| | - Paul Dowling
- Department of Biology, National University of Ireland, Maynooth, Ireland
| | - Laurie Maynadier
- mRNA Regulation and Development, Institut de Génétique Humaine, CNRS UPR1142, Montpellier, France
| | - Maëlle Bellec
- mRNA Regulation and Development, Institut de Génétique Humaine, CNRS UPR1142, Montpellier, France
| | - Martine Oloko
- Sorbonne Universités, UPMC Univ Paris 06, UM76, INSERM UMRS974, CNRS FRE3617, Center for Research in Myology, Paris, France
| | - Claude Jardel
- Service de Biochimie Métabolique et Centre de Génétique moléculaire et chromosomique, INSERM U1016, Institut Cochin, CNRS UMR 8104, AP-HP, GHU Pitié-Salpêtrière, Paris, France
| | - Bodo Moritz
- Institute of Biochemistry and Biotechnology, Martin Luther University Halle-Wittenberg, Halle, Germany
| | - George Dickson
- School of Biological Sciences, Royal Holloway - University of London, Egham, Surrey, United Kingdom
| | - Vincent Mouly
- Sorbonne Universités, UPMC Univ Paris 06, UM76, INSERM UMRS974, CNRS FRE3617, Center for Research in Myology, Paris, France
| | - Kay Ohlendieck
- Department of Biology, National University of Ireland, Maynooth, Ireland
| | - Gillian Butler-Browne
- Sorbonne Universités, UPMC Univ Paris 06, UM76, INSERM UMRS974, CNRS FRE3617, Center for Research in Myology, Paris, France
| | - Capucine Trollet
- Sorbonne Universités, UPMC Univ Paris 06, UM76, INSERM UMRS974, CNRS FRE3617, Center for Research in Myology, Paris, France
| | - Martine Simonelig
- mRNA Regulation and Development, Institut de Génétique Humaine, CNRS UPR1142, Montpellier, France
- * E-mail:
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Thomas MG, Pascual ML, Maschi D, Luchelli L, Boccaccio GL. Synaptic control of local translation: the plot thickens with new characters. Cell Mol Life Sci 2014; 71:2219-39. [PMID: 24212248 PMCID: PMC11113725 DOI: 10.1007/s00018-013-1506-y] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/09/2013] [Revised: 10/11/2013] [Accepted: 10/21/2013] [Indexed: 12/18/2022]
Abstract
The production of proteins from mRNAs localized at the synapse ultimately controls the strength of synaptic transmission, thereby affecting behavior and cognitive functions. The regulated transcription, processing, and transport of mRNAs provide dynamic control of the dendritic transcriptome, which includes thousands of messengers encoding multiple cellular functions. Translation is locally modulated by synaptic activity through a complex network of RNA-binding proteins (RBPs) and various types of non-coding RNAs (ncRNAs) including BC-RNAs, microRNAs, piwi-interacting RNAs, and small interference RNAs. The RBPs FMRP and CPEB play a well-established role in synaptic translation, and additional regulatory factors are emerging. The mRNA repressors Smaug, Nanos, and Pumilio define a novel pathway for local translational control that affects dendritic branching and spines in both flies and mammals. Recent findings support a role for processing bodies and related synaptic mRNA-silencing foci (SyAS-foci) in the modulation of synaptic plasticity and memory formation. The SyAS-foci respond to different stimuli with changes in their integrity thus enabling regulated mRNA release followed by translation. CPEB, Pumilio, TDP-43, and FUS/TLS form multimers through low-complexity regions related to prion domains or polyQ expansions. The oligomerization of these repressor RBPs is mechanistically linked to the aggregation of abnormal proteins commonly associated with neurodegeneration. Here, we summarize the current knowledge on how specificity in mRNA translation is achieved through the concerted action of multiple pathways that involve regulatory ncRNAs and RBPs, the modification of translation factors, and mRNA-silencing foci dynamics.
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Affiliation(s)
- María Gabriela Thomas
- Instituto Leloir, Av. Patricias Argentinas 435, C1405BWE Buenos Aires, Argentina
- IIBBA-CONICET, C1405BWE Buenos Aires, Argentina
| | - Malena Lucía Pascual
- Instituto Leloir, Av. Patricias Argentinas 435, C1405BWE Buenos Aires, Argentina
- IIBBA-CONICET, C1405BWE Buenos Aires, Argentina
- Facultad de Ciencias Exactas y Naturales, University of Buenos Aires, Buenos Aires, Argentina
| | - Darío Maschi
- Instituto Leloir, Av. Patricias Argentinas 435, C1405BWE Buenos Aires, Argentina
- Present Address: Department of Cell Biology and Physiology, Washington University School of Medicine, St. Louis, MO USA
| | - Luciana Luchelli
- Instituto Leloir, Av. Patricias Argentinas 435, C1405BWE Buenos Aires, Argentina
- IIBBA-CONICET, C1405BWE Buenos Aires, Argentina
| | - Graciela Lidia Boccaccio
- Instituto Leloir, Av. Patricias Argentinas 435, C1405BWE Buenos Aires, Argentina
- IIBBA-CONICET, C1405BWE Buenos Aires, Argentina
- Facultad de Ciencias Exactas y Naturales, University of Buenos Aires, Buenos Aires, Argentina
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Mutation of mouse Samd4 causes leanness, myopathy, uncoupled mitochondrial respiration, and dysregulated mTORC1 signaling. Proc Natl Acad Sci U S A 2014; 111:7367-72. [PMID: 24799716 DOI: 10.1073/pnas.1406511111] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022] Open
Abstract
Sterile alpha motif domain containing protein 4 (Samd4) is an RNA binding protein that mediates translational repression. We identified a Samd4 missense mutation, designated supermodel, that caused leanness and kyphosis associated with myopathy and adipocyte defects in C57BL/6J mice. The supermodel mutation protected homozygous mice from high fat diet-induced obesity, likely by promoting enhanced energy expenditure through uncoupled mitochondrial respiration. Glucose tolerance was impaired due to diminished insulin release in homozygous mutant mice. The defects of metabolism in supermodel mice may be explained by dysregulated mechanistic target of rapamycin complex 1 (mTORC1) signaling, evidenced by hypophosphorylation of 4E-BP1 and S6 in muscle and adipose tissues of homozygous mice. Samd4 may interface with mTORC1 signaling through an interaction with 14-3-3 proteins and with Akt, which phosphorylates Samd4 in vitro.
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Chen L, Dumelie JG, Li X, Cheng MH, Yang Z, Laver JD, Siddiqui NU, Westwood JT, Morris Q, Lipshitz HD, Smibert CA. Global regulation of mRNA translation and stability in the early Drosophila embryo by the Smaug RNA-binding protein. Genome Biol 2014; 15:R4. [PMID: 24393533 PMCID: PMC4053848 DOI: 10.1186/gb-2014-15-1-r4] [Citation(s) in RCA: 74] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/22/2013] [Accepted: 01/07/2014] [Indexed: 12/12/2022] Open
Abstract
Background Smaug is an RNA-binding protein that induces the degradation and represses the translation of mRNAs in the early Drosophila embryo. Smaug has two identified direct target mRNAs that it differentially regulates: nanos and Hsp83. Smaug represses the translation of nanos mRNA but has only a modest effect on its stability, whereas it destabilizes Hsp83 mRNA but has no detectable effect on Hsp83 translation. Smaug is required to destabilize more than one thousand mRNAs in the early embryo, but whether these transcripts represent direct targets of Smaug is unclear and the extent of Smaug-mediated translational repression is unknown. Results To gain a panoramic view of Smaug function in the early embryo, we identified mRNAs that are bound to Smaug using RNA co-immunoprecipitation followed by hybridization to DNA microarrays. We also identified mRNAs that are translationally repressed by Smaug using polysome gradients and microarrays. Comparison of the bound mRNAs to those that are translationally repressed by Smaug and those that require Smaug for their degradation suggests that a large fraction of Smaug’s target mRNAs are both translationally repressed and degraded by Smaug. Smaug directly regulates components of the TRiC/CCT chaperonin, the proteasome regulatory particle and lipid droplets, as well as many metabolic enzymes, including several glycolytic enzymes. Conclusions Smaug plays a direct and global role in regulating the translation and stability of a large fraction of the mRNAs in the early Drosophila embryo, and has unanticipated functions in control of protein folding and degradation, lipid droplet function and metabolism.
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Hlawatsch J, Karlstetter M, Aslanidis A, Lückoff A, Walczak Y, Plank M, Böck J, Langmann T. Sterile alpha motif containing 7 (samd7) is a novel crx-regulated transcriptional repressor in the retina. PLoS One 2013; 8:e60633. [PMID: 23565263 PMCID: PMC3615016 DOI: 10.1371/journal.pone.0060633] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/18/2012] [Accepted: 03/01/2013] [Indexed: 11/18/2022] Open
Abstract
Inherited retinal diseases are mainly caused by mutations in genes that are highly expressed in photoreceptors of the retina. The majority of these genes is under the control of the transcription factor Cone rod homeobox (Crx), that acts as a master transcription factor in photoreceptors. Using a genome-wide chromatin immunoprecipitation dataset that highlights all potential in vivo targets of Crx, we have identified a novel sterile alpha motif (SAM) domain containing protein, Samd7. mRNA Expression of Samd7 was confined to the late postnatal and adult mouse retina as well as the pineal gland. Using immunohistochemistry and Western blot, we could detect Samd7 protein in the outer nuclear layer of adult mouse retina. Ectopic over-expression in HEK293 cells demonstrated that Samd7 resides in the cytoplasm as well as the nucleus. In vitro electroporation of fluorescent reporters into living mouse retinal cultures revealed that transcription of the Samd7 gene depends on evolutionary conserved Crx motifs located in the first intron enhancer. Moreover, Crx knock-down with shRNA strongly reduced Samd7 reporter activity and endogenous Samd7 protein, indicating that Crx is required for retinal expression of Samd7. Finally, using co-transfections in luciferase reporter assays we found that Samd7 interferes with Crx-dependent transcription. Samd7 suppressed luciferase activity from a reporter plasmid with five Crx consensus repeats in a dose dependent manner and reduced Crx-mediated transactivation of regulatory sequences in the retinoschisin gene and the Samd7 gene itself. Taken together, we have identified a novel retinal SAM domain protein, Samd7, which could act as a transcriptional repressor involved in fine-tuning of Crx-regulated gene expression.
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Affiliation(s)
- Julia Hlawatsch
- Institute of Human Genetics, University of Regensburg, Regensburg, Germany
| | - Marcus Karlstetter
- Institute of Human Genetics, University of Regensburg, Regensburg, Germany
- Department of Ophthalmology, University of Cologne, Cologne, Germany
| | - Alexander Aslanidis
- Institute of Human Genetics, University of Regensburg, Regensburg, Germany
- Department of Ophthalmology, University of Cologne, Cologne, Germany
| | - Anika Lückoff
- Department of Ophthalmology, University of Cologne, Cologne, Germany
| | - Yana Walczak
- Institute of Human Genetics, University of Regensburg, Regensburg, Germany
- Department of Ophthalmology, University of Cologne, Cologne, Germany
| | - Michael Plank
- Institute of Human Genetics, University of Regensburg, Regensburg, Germany
| | - Julia Böck
- Institute of Human Genetics, University of Regensburg, Regensburg, Germany
| | - Thomas Langmann
- Institute of Human Genetics, University of Regensburg, Regensburg, Germany
- Department of Ophthalmology, University of Cologne, Cologne, Germany
- * E-mail:
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Pinder BD, Smibert CA. Smaug: an unexpected journey into the mechanisms of post-transcriptional regulation. Fly (Austin) 2013; 7:142-5. [PMID: 23519205 DOI: 10.4161/fly.24336] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022] Open
Abstract
Drosophila Smaug is a sequence-specific RNA-binding protein that can repress the translation and induce the degradation of target mRNAs in the early Drosophila embryo. Our recent work has uncovered a new mechanism of Smaug-mediated translational repression whereby it interacts with and recruits the Argonaute 1 (Ago1) protein to an mRNA. Argonaute proteins are typically recruited to mRNAs through an associated small RNA, such as a microRNA (miRNA). Surprisingly, we found that Smaug is able to recruit Ago1 to an mRNA in a miRNA-independent manner. This work suggests that other RNA-binding proteins are likely to employ a similar mechanism of miRNA-independent Ago recruitment to control mRNA expression. Our work also adds yet another mechanism to the list that Smaug can use to regulate its targets and here we discuss some of the issues that are raised by Smaug's multi-functional nature.
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Affiliation(s)
- Benjamin D Pinder
- Department of Biochemistry; University of Toronto; Toronto, ON Canada
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Rendl LM, Bieman MA, Vari HK, Smibert CA. The eIF4E-binding protein Eap1p functions in Vts1p-mediated transcript decay. PLoS One 2012; 7:e47121. [PMID: 23071728 PMCID: PMC3468468 DOI: 10.1371/journal.pone.0047121] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/16/2012] [Accepted: 09/10/2012] [Indexed: 01/06/2023] Open
Abstract
Sequence-specific RNA binding proteins can induce the degradation of mRNAs through their ability to recruit proteins that trigger transcript destabilization. For example, Vts1p, the S. cerevisiae member of the Smaug family of RNA binding proteins, is thought to induce transcript decay by recruiting the Ccr4p-Pop2p-Not deadenylase complex to target mRNAs. The resulting deadenylation triggers transcript decapping followed by 5′-to-3′ exonucleolytic decay. Here we show that the eIF4E-binding protein, Eap1p, is required for efficient degradation of Vts1p target transcripts and that this role involves the ability of Eap1p to interact with eIF4E. Eap1p does not stimulate deadenylation of Vts1p target transcripts but is instead involved in decapping. Eap1p interacts with Vts1p and mediates an indirect interaction between Vts1p and eIF4E. Taken together these data suggest a model whereby the interaction of Vts1p with Eap1p at target mRNAs stimulates decapping.
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Affiliation(s)
- Laura M. Rendl
- Department of Biochemistry, University of Toronto, Toronto, Ontario, Canada
| | - Melissa A. Bieman
- Department of Biochemistry, University of Toronto, Toronto, Ontario, Canada
| | - Heli K. Vari
- Department of Biochemistry, University of Toronto, Toronto, Ontario, Canada
| | - Craig A. Smibert
- Department of Biochemistry, University of Toronto, Toronto, Ontario, Canada
- Department of Molecular Genetics, University of Toronto, Toronto, Ontario, Canada
- * E-mail:
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Gebauer F, Preiss T, Hentze MW. From cis-regulatory elements to complex RNPs and back. Cold Spring Harb Perspect Biol 2012; 4:a012245. [PMID: 22751153 DOI: 10.1101/cshperspect.a012245] [Citation(s) in RCA: 63] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
Abstract
Messenger RNAs (mRNAs), the templates for translation, have evolved to harbor abundant cis-acting sequences that affect their posttranscriptional fates. These elements are frequently located in the untranslated regions and serve as binding sites for trans-acting factors, RNA-binding proteins, and/or small non-coding RNAs. This article provides a systematic synopsis of cis-acting elements, trans-acting factors, and the mechanisms by which they affect translation. It also highlights recent technical advances that have ushered in the era of transcriptome-wide studies of the ribonucleoprotein complexes formed by mRNAs and their trans-acting factors.
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Affiliation(s)
- Fátima Gebauer
- Gene Regulation Programme, Centre for Genomic Regulation (CRG) and UPF, 08003-Barcelona, Spain.
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35
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Soundararajan R, Lu M, Pearce D. Organization of the ENaC-regulatory machinery. Crit Rev Biochem Mol Biol 2012; 47:349-59. [PMID: 22506713 DOI: 10.3109/10409238.2012.678285] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
The control of fluid and electrolyte homeostasis in vertebrates requires the integration of a diverse set of signaling inputs, which control epithelial Na(+) transport, the principal ionic component of extracellular fluid. The key site of regulation is a segment of the kidney tubules, frequently termed the aldosterone-sensitive distal nephron, wherein the epithelial Na(+) channel (or ENaC) mediates apical ion entry. Na(+) transport in this segment is strongly regulated by the salt-retaining hormone, aldosterone, which acts through the mineralocorticoid receptor (MR) to influence the expression of a selected set of target genes, most notably the serine-threonine kinase SGK1, which phosphorylates and inhibits the E3 ubiquitin ligase Nedd4-2. It has long been known that ENaC activity is tightly regulated in vertebrate epithelia. Recent evidence suggests that SGK1 and Nedd4-2, along with other ENaC-regulatory proteins, physically associate with each other and with ENaC in a multi-protein complex. The various components of the complex are regulated by diverse signaling networks, including steroid receptor-, PI3-kinase-, mTOR-, and Raf-MEK-ERK-dependent pathways. In this review, we focus on the organization of the targets of these pathways by multi-domain scaffold proteins and lipid platforms into a unified complex, thereby providing a molecular basis for signal integration in the control of ENaC.
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Affiliation(s)
- Rama Soundararajan
- Division of Nephrology, Department of Medicine, University of California San Francisco, San Francisco, CA 94143, USA
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36
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Inoue H, Baba T, Sato S, Ohtsuki R, Takemori A, Watanabe T, Tagaya M, Tani K. Roles of SAM and DDHD domains in mammalian intracellular phospholipase A1 KIAA0725p. BIOCHIMICA ET BIOPHYSICA ACTA-MOLECULAR CELL RESEARCH 2012; 1823:930-9. [DOI: 10.1016/j.bbamcr.2012.02.002] [Citation(s) in RCA: 51] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/27/2011] [Revised: 01/31/2012] [Accepted: 02/01/2012] [Indexed: 10/28/2022]
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Baez MV, Luchelli L, Maschi D, Habif M, Pascual M, Thomas MG, Boccaccio GL. Smaug1 mRNA-silencing foci respond to NMDA and modulate synapse formation. ACTA ACUST UNITED AC 2012; 195:1141-57. [PMID: 22201125 PMCID: PMC3246892 DOI: 10.1083/jcb.201108159] [Citation(s) in RCA: 43] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
S-foci, the first reported mRNA-silencing foci specific to neurons, may control local mRNA translation in response to NMDA receptor stimulation and synaptic plasticity. Mammalian Smaug1/Samd4A is a translational repressor. Here we show that Smaug1 forms mRNA-silencing foci located at postsynapses of hippocampal neurons. These structures, which we have named S-foci, are distinct from P-bodies, stress granules, or other neuronal RNA granules hitherto described, and are the first described mRNA-silencing foci specific to neurons. RNA binding was not required for aggregation, which indicates that S-foci formation is not a consequence of mRNA silencing. N-methyl-d-aspartic acid (NMDA) receptor stimulation provoked a rapid and reversible disassembly of S-foci, transiently releasing transcripts (the CaMKIIα mRNA among others) to allow their translation. Simultaneously, NMDA triggered global translational silencing, which suggests the specific activation of Smaug1-repressed transcripts. Smaug1 is expressed during synaptogenesis, and Smaug1 knockdown affected the number and size of synapses, and also provoked an impaired response to repetitive depolarizing stimuli, as indicated by a reduced induction of Arc/Arg3.1. Our results suggest that S-foci control local translation, specifically responding to NMDA receptor stimulation and affecting synaptic plasticity.
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Abstract
Translational regulation plays an essential role in many phases of the Drosophila life cycle. During embryogenesis, specification of the developing body pattern requires co-ordination of the translation of oskar, gurken and nanos mRNAs with their subcellular localization. In addition, dosage compensation is controlled by Sex-lethal-mediated translational regulation while dFMR1 (the Drosophila homologue of the fragile X mental retardation protein) controls translation of various mRNAs which function in the nervous system. Here we describe some of the mechanisms that are utilized to regulate these various processes. Our review highlights the complexity that can be involved with multiple factors employing different mechanisms to control the translation of a single mRNA.
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Affiliation(s)
- James E Wilhelm
- Department of Embryology, Carnegie Institution of Washington, Baltimore, MD 21210, USA
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39
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Rufini S, Lena AM, Cadot B, Mele S, Amelio I, Terrinoni A, Desideri A, Melino G, Candi E. The sterile alpha-motif (SAM) domain of p63 binds in vitro monoasialoganglioside (GM1) micelles. Biochem Pharmacol 2011; 82:1262-8. [DOI: 10.1016/j.bcp.2011.07.087] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/31/2011] [Revised: 07/20/2011] [Accepted: 07/20/2011] [Indexed: 10/17/2022]
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40
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Sathyamurthy A, Freund SMV, Johnson CM, Allen MD, Bycroft M. Structural basis of p63α SAM domain mutants involved in AEC syndrome. FEBS J 2011; 278:2680-8. [DOI: 10.1111/j.1742-4658.2011.08194.x] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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41
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Gorman MA, Uboldi AD, Walsh PJ, Tan KS, Hansen G, Huyton T, Ji H, Curtis J, Kedzierski L, Papenfuss AT, Dogovski C, Perugini MA, Simpson RJ, Handman E, Parker MW. Crystal structure of the Leishmania major MIX protein: a scaffold protein that mediates protein-protein interactions. Protein Sci 2011; 20:1060-8. [PMID: 21465610 PMCID: PMC3104235 DOI: 10.1002/pro.631] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/27/2011] [Revised: 03/15/2011] [Accepted: 03/22/2011] [Indexed: 01/07/2023]
Abstract
Infection by Leishmania and Trypanosoma causes severe disease and can be fatal. The reduced effectiveness of current treatments is largely due to drug resistance, hence the urgent need to develop new drugs, preferably against novel targets. We have recently identified a mitochondrial membrane-anchored protein, designated MIX, which occurs exclusively in these parasites and is essential for virulence. We have determined the crystal structure of Leishmania major MIX to a resolution of 2.4 Å. MIX forms an all α-helical fold comprising seven α-helices that fold into a single domain. The distribution of helices is similar to a number of scaffold proteins, namely HEAT repeats, 14-3-3, and tetratricopeptide repeat proteins, suggesting that MIX mediates protein-protein interactions. Accordingly, using copurification and mass spectroscopy we were able to identify several proteins that may interact with MIX in vivo. Being parasite specific, MIX is a promising new drug target and, thus, the structure and potential interacting partners provide a basis for structure-guided drug discovery.
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Affiliation(s)
- Michael A Gorman
- Biota Structural Biology Laboratory, St. Vincent's Institute of Medical ResearchVictoria 3065, Australia
| | - Alex D Uboldi
- Infection and Immunity Division, The Walter and Eliza Hall Institute of Medical ResearchVictoria 3052, Australia
| | - Peter J Walsh
- Biota Structural Biology Laboratory, St. Vincent's Institute of Medical ResearchVictoria 3065, Australia
| | - Kher Shing Tan
- Biota Structural Biology Laboratory, St. Vincent's Institute of Medical ResearchVictoria 3065, Australia
| | - Guido Hansen
- Biota Structural Biology Laboratory, St. Vincent's Institute of Medical ResearchVictoria 3065, Australia
| | - Trevor Huyton
- The Australia Synchrotron800 Blackburn Road, Victoria 3168, Australia
| | - Hong Ji
- Ludwig Institute for Cancer ResearchVictoria 3050, Australia
| | - Joan Curtis
- Infection and Immunity Division, The Walter and Eliza Hall Institute of Medical ResearchVictoria 3052, Australia
| | - Lukasz Kedzierski
- Infection and Immunity Division, The Walter and Eliza Hall Institute of Medical ResearchVictoria 3052, Australia
| | - Anthony T Papenfuss
- Bioinformatics Division, The Walter and Eliza Hall Institute of Medical ResearchVictoria 3052, Australia
| | - Con Dogovski
- Department of Biochemistry and Molecular Biology, Bio21 Molecular Science and Biotechnology Institute, The University of MelbourneVictoria 3010, Australia
| | - Matthew A Perugini
- Department of Biochemistry and Molecular Biology, Bio21 Molecular Science and Biotechnology Institute, The University of MelbourneVictoria 3010, Australia
| | | | - Emanuela Handman
- Infection and Immunity Division, The Walter and Eliza Hall Institute of Medical ResearchVictoria 3052, Australia
| | - Michael W Parker
- Biota Structural Biology Laboratory, St. Vincent's Institute of Medical ResearchVictoria 3065, Australia,Department of Biochemistry and Molecular Biology, Bio21 Molecular Science and Biotechnology Institute, The University of MelbourneVictoria 3010, Australia,*Correspondence to: Michael W. Parker, St. Vincent's Institute of Medical Research, 41 Victoria Parade, Fitzroy, Victoria 3065, Australia. E-mail:
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Fritz RD, Radziwill G. CNK1 and other scaffolds for Akt/FoxO signaling. BIOCHIMICA ET BIOPHYSICA ACTA-MOLECULAR CELL RESEARCH 2011; 1813:1971-7. [PMID: 21320536 DOI: 10.1016/j.bbamcr.2011.02.008] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/15/2010] [Revised: 02/01/2011] [Accepted: 02/05/2011] [Indexed: 11/28/2022]
Abstract
FoxO transcription factors mediate anti-proliferative and pro-apoptotic signals and act as tumor suppressors in cancer. Posttranslational modifications including phosphorylation and acetylation regulate FoxO activity by a cytoplasmic-nuclear shuttle mechanism. Scaffold proteins coordinating signaling pathways in time and space play a critical role in this process. CNK1 acts as a scaffold protein in several signaling pathways controlling the function of FoxO proteins. An understanding of CNK1 and other scaffolds in the FoxO signaling network will provide insights how to release the tumor suppressor function of FoxO as a possibility to block oncogenic pathways. This article is part of a Special Issue entitled: P13K-AKT-FoxO axis in cancer and aging.
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Affiliation(s)
- Rafael D Fritz
- Department of Biomedicine, Institute of Biochemistry and Genetics, University of Basel, Mattenstrasse 28, CH-4058 Basel, Switzerland.
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43
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Lee CH, Shin YK, Phung TTH, Bae JS, Kang YH, Nguyen TA, Kim JH, Kim DH, Kang MJ, Bae SH, Seo YS. Involvement of Vts1, a structure-specific RNA-binding protein, in Okazaki fragment processing in yeast. Nucleic Acids Res 2009; 38:1583-95. [PMID: 20007605 PMCID: PMC2836565 DOI: 10.1093/nar/gkp1135] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/21/2023] Open
Abstract
The non-essential VTS1 gene of Saccharomyces cerevisiae is highly conserved in eukaryotes and encodes a sequence- and structure-specific RNA-binding protein. The Vts1 protein has been implicated in post-transcriptional regulation of a specific set of mRNAs that contains its-binding site at their 3'-untranslated region. In this study, we identified VTS1 as a multi-copy suppressor of dna2-K1080E, a lethal mutant allele of DNA2 that lacks DNA helicase activity. The suppression was allele-specific, since overexpression of Vts1 did not suppress the temperature-dependent growth defects of dna2Delta405N devoid of the N-terminal 405-amino-acid residues. Purified recombinant Vts1 stimulated the endonuclease activity of wild-type Dna2, but not the endonuclease activity of Dna2Delta405N, indicating that the activation requires the N-terminal domain of Dna2. Stimulation of Dna2 endonuclease activity by Vts1 appeared to be the direct cause of suppression, since the multi-copy expression of Dna2-K1080E suppressed the lethality observed with its single-copy expression. We found that vts1Delta dna2Delta405N and vts1Deltadna2-7 double mutant cells displayed synergistic growth defects, in support of a functional interaction between two genes. Our results provide both in vivo and in vitro evidence that Vts1 is involved in lagging strand synthesis by modulating the Dna2 endonuclease activity that plays an essential role in Okazaki fragment processing.
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Affiliation(s)
- Chul-Hwan Lee
- Center for DNA Replication and Genome Instability, Department of Biological Sciences, Korea Advanced Institute of Science and Technology, Daejeon 305-701, Korea
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The importance of Src homology 2 domain-containing leukocyte phosphoprotein of 76 kilodaltons sterile-alpha motif domain in thymic selection and T-cell activation. Blood 2009; 114:74-84. [PMID: 19401562 DOI: 10.1182/blood-2008-09-177832] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022] Open
Abstract
The Src homology 2 domain-containing leukocyte phosphoprotein of 76 kilodaltons (SLP-76) is a cytosolic adaptor protein essential for thymocyte development and T-cell activation. It contains a sterile-alpha motif (SAM) domain, 3 phosphotyrosine motifs, a proline-rich region, and a Src homology 2 domain. Whereas the other domains have been extensively studied, the role of the SAM domain in SLP-76 function is not known. To understand the function of this domain, we generated SLP-76 knockin mice with the SAM domain deleted. Analysis of these mice showed that thymocyte development was partially blocked at the double-positive to single-positive transition. Positive and negative thymic selection was also impaired. In addition, we analyzed T-cell receptor (TCR)-mediated signaling in T cells from these mutant mice. TCR-mediated inositol 1,4,5-triphosphate production, calcium flux, and extracellular signal-regulated kinase activation were decreased, leading to defective interleukin-2 production and proliferation. Moreover, despite normal association between Gads and SLP-76, TCR-mediated formation of SLP-76 microclusters was impaired by the deletion of the SAM domain. Altogether, our data demonstrated that the SAM domain is indispensable for optimal SLP-76 signaling.
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Yang S, Noble CG, Yang D. Characterization of DLC1-SAM Equilibrium Unfolding at the Amino Acid Residue Level. Biochemistry 2009; 48:4040-9. [DOI: 10.1021/bi9000936] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Shuai Yang
- Department of Chemistry, 3 Science Drive 3, Faculty of Science, National University of Singapore, Singapore 117543
| | - Christian G. Noble
- Institute of Molecular and Cell Biology, 61 Biopolis Drive, Proteos, Singapore 138673
| | - Daiwen Yang
- Department of Biological Sciences, 14 Science Drive 4, Faculty of Science, National University of Singapore, Singapore 117543
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Bhunia A, Domadia PN, Mohanram H, Bhattacharjya S. NMR structural studies of the Ste11 SAM domain in the dodecyl phosphocholine micelle. Proteins 2009; 74:328-43. [PMID: 18618697 DOI: 10.1002/prot.22166] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Abstract
The sterile alpha-motif (SAM), a relatively small ( approximately 70 amino acids) interaction domain, is found in a variety of proteins involved in cell signaling, transcription regulation, and scaffolding. The Ste11 protein kinase from the mitogen activated protein kinase (MAPK) signaling cascades of the budding yeast is regulated by a SAM domain located at the N-terminus of full-length protein. In solution, the Ste11 SAM domain exists as a well-folded dimeric structure that is involved in interaction with the cognate SAM domain from an adaptor protein Ste50. In this work, we show that the Ste11 SAM domain has an intrinsic affinity towards the lipid membranes. The solution conformation of the Ste11 SAM determined in perdeuterated DPC micelle, using NMR spectroscopy, is defined by five helices of different lengths connected by a number of loops. In the micelle bound state, the non-polar and aromatic residues of the Ste11 SAM lack a native-like packing and are presumably engaged in interactions with the micelle. Using two different paramagnetic doxyl-lipids; we have mapped out localization of Ste11 SAM residues at the micelle surface. Most of the residues appear to localize at the interfacial region of the micelle. However, a number of non-polar residues from the central region of the domain are found to be located inside the core of the micelle including residues from the helix 4 and a loop between helix 2 and helix 3. Isothermal titration calorimetry studies demonstrate that a facile insertion of the Ste11 SAM into the DPC micelle is primarily driven by a large change in enthalpy, -50 kcal/mol with an apparent equilibrium association constant (Ka) of 7.86 x 10(6) M(-1). Interestingly, an interfacial mutant L60R of the Ste11 SAM lacking the dimeric structure does not show detectable interactions with the lipid micelle. The micelle-bound structure of the Ste11 SAM domain described in this work may have potential implications in the regulation of MAPK signaling whereby positioning of the Ste11 protein in close proximity to the membrane may facilitate efficient phosphorylation of the Ste11 kinase by the membrane attached upstream Ste20/pak kinase.
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Affiliation(s)
- Anirban Bhunia
- Biomolecular NMR and Drug Discovery Laboratory, Division of Structural and Computational Biology, School of Biological Sciences, Nanyang Technological University, Singapore
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Abstract
Sterile alpha motif (SAM) domains are common protein modules in eukaryotic cells. It has not been possible to assign functions to uncharacterized SAM domains because they have been found to participate in diverse functions ranging from protein-protein interactions to RNA binding. Here we computationally identify likely members of the subclass of SAM domains that form polymers. Sequences were virtually threaded onto known polymer structures and then evaluated for compatibility with the polymer. We find that known SAM polymers score better than the vast majority of known nonpolymers: 100% (7 of 7) of known polymers and only 8% of known nonpolymers (1 of 12) score above a defined threshold value. Of 2901 SAM family members, we find 694 that score above the threshold and are likely polymers, including SAM domains from the proteins Lethal Malignant Brain Tumor, Bicaudal-C, Liprin-beta, Adenylate Cyclase, and Atherin.
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Affiliation(s)
- Alejandro D Meruelo
- Medical Scientist Training Program, UCLA-DOE Institute for Genomics and Proteomics, Molecular Biology Institute, UCLA, Los Angeles, California 90095-1570, USA
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Rendl LM, Bieman MA, Smibert CA. S. cerevisiae Vts1p induces deadenylation-dependent transcript degradation and interacts with the Ccr4p-Pop2p-Not deadenylase complex. RNA (NEW YORK, N.Y.) 2008; 14:1328-36. [PMID: 18469165 PMCID: PMC2441989 DOI: 10.1261/rna.955508] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/09/2023]
Abstract
The Smaug family of sequence-specific RNA binding proteins regulates mRNA translation and degradation by binding to consensus stem-loop structures in target mRNAs. Vts1p is a member of the Smaug protein family that regulates the stability of target transcripts in Saccharomyces cerevisiae. Here we focus on the mechanism of Vts1p-mediated mRNA decay. Using RNA reporters that recapitulate Vts1p-mediated decay in vivo, we demonstrate that Vts1p stimulates mRNA degradation through deadenylation mediated by the Ccr4p-Pop2p-Not deadenylase complex. We also show that Vts1p interacts with the Ccr4p-Pop2p-Not complex suggesting that Vts1p recruits the Ccr4p-Pop2p-Not deadenylase complex to target mRNAs, resulting in transcript decay. Following deadenylation Vts1p target transcripts are decapped and subsequently degraded by the 5'-to-3' exonuclease Xrn1p. Decapping and 5'-to-3' decay is thought to occur in foci known as P-bodies, and we provide evidence that Vts1p function may involve P-bodies. Taken together with previous work, these data suggest that Smaug family members employ a conserved mechanism to induce transcript degradation that involves recruitment of the Ccr4-Pop2-Not deadenylase to target mRNAs.
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Affiliation(s)
- Laura M Rendl
- Department of Biochemistry, University of Toronto, Toronto, Ontario M5S 1A8, Canada
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Horvilleur E, Bauer M, Goldschneider D, Mergui X, de la Motte A, Bénard J, Douc-Rasy S, Cappellen D. p73alpha isoforms drive opposite transcriptional and post-transcriptional regulation of MYCN expression in neuroblastoma cells. Nucleic Acids Res 2008; 36:4222-32. [PMID: 18583365 PMCID: PMC2490757 DOI: 10.1093/nar/gkn394] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022] Open
Abstract
MYCN activation, mainly by gene amplification, is one of the most frequent molecular events in neuroblastoma (NB) oncogenesis, and is associated with increased malignancy and decreased neuronal differentiation propensity. The frequency of concomitant loss of heterozygosity at the 1p36.3 locus, which harbours the p53 anti-oncogene homologue TP73, indicates that MYCN and p73 alterations may cooperate in the pathogenesis of NB. We have previously shown that p73 isoforms are deregulated in NB tumours and that TAp73 co-operates synergistically with p53 for apoptosis of NB cells, whereas ΔNp73 activates the expression of neuronal differentiation genes such as BTG2. Herein, using both ectopic expression and RNA interference-mediated silencing of p73 in MYCN amplified NB cells, we show that p73α isoforms inhibit MYCN expression at both transcript and protein levels, in spite of transactivator effects on MYCN promoter. To explain this paradox, we found that TAp73α exerts negative post-transcriptional effects leading to reduced MYCN mRNA stability. RNA immunoprecipitation experiments suggest that this dominant inhibitory post-transcriptional effect could be due to an interaction between the p73 protein and MYCN mRNA, a hypothesis also raised for the regulation of certain genes by the p53 protein.
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Affiliation(s)
- Emilie Horvilleur
- Interactions Molécularies et Cancer, Unité Mixte de Recherche 8126, Centre National de Recherche Scientifique-Université Paris Sud-11, Institut de Cancérologie Gustave Roussy, 94805 Villejuif, France
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50
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CNK and HYP form a discrete dimer by their SAM domains to mediate RAF kinase signaling. Proc Natl Acad Sci U S A 2008; 105:2836-41. [PMID: 18287031 DOI: 10.1073/pnas.0709705105] [Citation(s) in RCA: 39] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
RAF kinase functions in the mitogen-activated protein kinase (MAPK) pathway to transmit growth signals to the downstream kinases MEK and ERK. Activation of RAF catalytic activity is facilitated by a regulatory complex comprising the proteins CNK (Connector enhancer of KSR), HYP (Hyphen), and KSR (Kinase Suppressor of Ras). The sterile alpha-motif (SAM) domain found in both CNK and HYP plays an essential role in complex formation. Here, we have determined the x-ray crystal structure of the SAM domain of CNK in complex with the SAM domain of HYP. The structure reveals a single-junction SAM domain dimer of 1:1 stoichiometry in which the binding mode is a variation of polymeric SAM domain interactions. Through in vitro and in vivo mutational analyses, we show that the specific mode of dimerization revealed by the crystal structure is essential for RAF signaling and facilitates the recruitment of KSR to form the CNK/HYP/KSR regulatory complex. We present two docking-site models to account for how SAM domain dimerization might influence the formation of a higher-order CNK/HYP/KSR complex.
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