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Onnée M, Bénézit A, Bastu S, Nadaj-Pakleza A, Lannes B, Ader F, Thèze C, Cintas P, Cances C, Carlier RY, Metay C, Cossée M, Malfatti E. The FLNC Ala1186Val Variant Linked to Cytoplasmic Body Myopathy and Cardiomyopathy Causes Protein Instability. Biomedicines 2024; 12:322. [PMID: 38397924 PMCID: PMC10887408 DOI: 10.3390/biomedicines12020322] [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: 12/29/2023] [Revised: 01/18/2024] [Accepted: 01/22/2024] [Indexed: 02/25/2024] Open
Abstract
Filamin C-related disorders include myopathies and cardiomyopathies linked to variants in the FLNC gene. Filamin C belongs to a family of actin-binding proteins involved in sarcomere stability. This study investigates the pathogenic impact of the FLNC c.3557C > T (p.Ala1186Val) pathogenic variant associated with an early-onset cytoplasmic body myopathy and cardiomyopathy in three unrelated patients. We performed clinical imaging and myopathologic and genetic characterization of three patients with an early-onset myopathy and cardiomyopathy. Bioinformatics analysis, variant interpretation, and protein structure analysis were performed to validate and assess the effects of the filamin C variant. All patients presented with a homogeneous clinical phenotype marked by a severe contractural myopathy, leading to loss of gait. There was prominent respiratory involvement and restrictive or hypertrophic cardiomyopathies. The Ala1186Val variant is located in the interstrand loop involved in intradomain stabilization and/or interdomain interactions with neighbor Ig-like domains. 3D modeling highlights local structural changes involving nearby residues and probably impacts the protein stability, causing protein aggregation in the form of cytoplasmic bodies. Myopathologic studies have disclosed the prominent aggregation and upregulation of the aggrephagy-associated proteins LC3B and p62. As a whole, the Ala1186Val variant in the FLNC gene provokes a severe myopathy with contractures, respiratory involvement, and cardiomyopathy due to protein aggregation in patients' muscles.
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Affiliation(s)
- Marion Onnée
- Institut Mondor de Recherche Biomédicale, Université Paris Est Créteil, Institut National de la Santé et de la Recherche Médicale U955, 94010 Créteil, France; (M.O.); (S.B.)
| | - Audrey Bénézit
- Neurologie et Réanimation Pédiatrique, Assistance Publique–Hôpitaux de Paris, Université Paris Saclay, Département Médico-Universitaire Santé de l’Enfant et de l’Adolescent, Hôpital Raymond Poincaré, 92380 Garches, France;
| | - Sultan Bastu
- Institut Mondor de Recherche Biomédicale, Université Paris Est Créteil, Institut National de la Santé et de la Recherche Médicale U955, 94010 Créteil, France; (M.O.); (S.B.)
| | - Aleksandra Nadaj-Pakleza
- Centre de Référence des Maladies Neuromusculaires Nord Est Ile-de-France, Service de Neurologie, Hôpitaux Universitaires de Strasbourg, 67200 Strasbourg, France;
- European Reference Network, EURO-NMD, Neuromuscular Centre at Hautepierre Hospital, Hôpitaux Universitaires de Strasbourg, 67200 Strasbourg, France
| | - Béatrice Lannes
- Département de Pathologie, Hôpitaux Universitaires de Strasbourg, 67091 Strasbourg, France;
| | - Flavie Ader
- Assistance Publique–Hôpitaux de Paris, Sorbonne Université, Département Médico-Universitaire BioGem, Unité Fonctionnelle de Cardiogénétique et Myogénétique Moléculaire et Cellulaire, 75013 Paris, France;
- Institut National de la Santé et de la Recherche Médicale UMRS1166, Université Paris Cité, 75006 Paris, France
| | - Corinne Thèze
- Laboratoire de Génétique Moléculaire, Centre Hospitalier Universitaire de Montpellier, Université de Montpellier, 34095 Montpellier, France;
| | - Pascal Cintas
- Centre de Référence des Maladies Neuromusculaires AOC (Atlantique-Occitanie-Caraïbes), Département de Neurologie, Hôpital Pierre-Paul Riquet, Centre Hospitalier Universitaire de Toulouse, 31059 Toulouse, France; (P.C.); (M.C.)
| | - Claude Cances
- Centre de Référence des Maladies Neuromusculaires AOC (Atlantique-Occitanie-Caraïbes), Unité de Neurologie Pédiatrique, Hôpital des Enfants, Centre Hospitalier Universitaire de Toulouse, 31059 Toulouse, France;
| | - Robert-Yves Carlier
- Assistance Publique–Hôpitaux de Paris, Groupe Hospitalier Universitaire Paris Saclay, Département Médico-Universitaire Smart Imaging, Service d’Imagerie Médicale, Institut National de la Santé et de la Recherche Médicale UMR1179, Hôpital Raymond Poincaré, 92380 Garches, France;
| | - Corinne Metay
- Unité Fonctionnelle de Cardiogénétique et Myogénétique Moléculaire et Cellulaire, Centre de Génétique Moléculaire et Chromosomique, Sorbonne Université, Institut National de la Santé et de la Recherche Médicale, Institut de Myologie, Groupe Hospitalier La Pitié-Salpêtrière, 75013 Paris, France;
| | - Mireille Cossée
- Centre de Référence des Maladies Neuromusculaires AOC (Atlantique-Occitanie-Caraïbes), Département de Neurologie, Hôpital Pierre-Paul Riquet, Centre Hospitalier Universitaire de Toulouse, 31059 Toulouse, France; (P.C.); (M.C.)
- PhyMedExp, Université de Montpellier, Institut National de la Santé et de la Recherche Médicale, Centre National de la Recherche Scientifique, 34295 Montpellier, France
| | - Edoardo Malfatti
- Institut Mondor de Recherche Biomédicale, Université Paris Est Créteil, Institut National de la Santé et de la Recherche Médicale U955, 94010 Créteil, France; (M.O.); (S.B.)
- Assistance Publique–Hôpitaux de Paris, Centre de Référence de Pathologie Neuromusculaire Nord-Est-Ile-de-France, Hôpital Henri Mondor, 94000 Créteil, France
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Lu YL, Wang Q, Wang M, Chang SH, He JQ, Xiang R, Tang JY, Jin JY. Identification of A Novel Variant of Filamin A Destroying the Attraction Between Benzene Rings and Sulfhydryl in Developmental Dysplasia of the Hip. DNA Cell Biol 2023; 42:638-644. [PMID: 37851024 DOI: 10.1089/dna.2023.0159] [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] [Indexed: 10/19/2023] Open
Abstract
Developmental dysplasia of the hip (DDH), characterized by acetabular deformity that manifests from loose ligaments to complete dislocation of the hip, can cause notable pain and dysfunction and lead to hip dislocation, secondary fractures, scoliosis, and osteoarthritis of hip. Variants in FLNA may produce a spectrum of malformations in multiple organs, especially the skeleton. This study aimed to identify the genetic etiologies of DDH patients and provide genetic testing information for further diagnosis and treatment of DDH. We recruited a Chinese woman with DDH and her family members. Whole-exome sequencing was used to identify the patient's genetic etiologies. Protein models were used to analyze the pathogenic mechanism of the identified variants. A novel variant (c.3493T>G, p.C1165G) of FLNA was detected. The structural models of the mutant FLNA protein indicated that the variant would lose its sulfhydryl side chain and destroy the attraction between benzene rings and sulfhydryl. We reported a novel variant (c.3493T>G, p.C1165G) of FLNA in a Chinese woman with DDH. Our research outcome enriches the gene pool for hip dysplasia and emphasizes the pathogenicity of sulfhydryl side chain disruption in FLNA.
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Affiliation(s)
- Yi-Lei Lu
- Department of Orthopaedics, Xiangya Hospital of Central South University, Changsha, China
- Microsurgery and Reconstruction Research Center, and Xiangya Hospital of Central South University, Changsha, China
- National Clinical Research Center for Geriatric Disorders, Xiangya Hospital of Central South University, Changsha, China
| | - Qin Wang
- National Clinical Research Center for Geriatric Disorders, Xiangya Hospital of Central South University, Changsha, China
- School of Life Sciences, Central South University, Changsha, China
- Department of Nephrology and Xiangya Hospital of Central South University, Changsha, China
| | - Min Wang
- National Clinical Research Center for Geriatric Disorders, Xiangya Hospital of Central South University, Changsha, China
- Department of Endocrinology, Xiangya Hospital of Central South University, Changsha, China
| | - Si-Hua Chang
- School of Life Sciences, Central South University, Changsha, China
| | - Ji-Qiang He
- Department of Orthopaedics, Xiangya Hospital of Central South University, Changsha, China
- Microsurgery and Reconstruction Research Center, and Xiangya Hospital of Central South University, Changsha, China
- National Clinical Research Center for Geriatric Disorders, Xiangya Hospital of Central South University, Changsha, China
| | - Rong Xiang
- Department of Orthopaedics, Xiangya Hospital of Central South University, Changsha, China
- School of Life Sciences, Central South University, Changsha, China
| | - Ju-Yu Tang
- Department of Orthopaedics, Xiangya Hospital of Central South University, Changsha, China
- Microsurgery and Reconstruction Research Center, and Xiangya Hospital of Central South University, Changsha, China
- National Clinical Research Center for Geriatric Disorders, Xiangya Hospital of Central South University, Changsha, China
| | - Jie-Yuan Jin
- Department of Orthopaedics, Xiangya Hospital of Central South University, Changsha, China
- Microsurgery and Reconstruction Research Center, and Xiangya Hospital of Central South University, Changsha, China
- National Clinical Research Center for Geriatric Disorders, Xiangya Hospital of Central South University, Changsha, China
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Bowman RL, Hennessey RC, Weiss TJ, Tallman DA, Crawford ER, Murphy BM, Webb A, Zhang S, La Perle KM, Burd CJ, Levine RL, Shain AH, Burd CE. UVB mutagenesis differs in Nras- and Braf-mutant mouse models of melanoma. Life Sci Alliance 2021; 4:e202101135. [PMID: 34210801 PMCID: PMC8321651 DOI: 10.26508/lsa.202101135] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/14/2021] [Revised: 06/22/2021] [Accepted: 06/22/2021] [Indexed: 12/14/2022] Open
Abstract
BRAF-mutant melanomas are more likely than NRAS-mutant melanomas to arise in anatomical locations protected from chronic sun damage. We hypothesized that this discrepancy in tumor location is a consequence of the differential sensitivity of BRAF and NRAS-mutant melanocytes to ultraviolet light (UV)-mediated carcinogenesis. We tested this hypothesis by comparing the mutagenic consequences of a single neonatal, ultraviolet-AI (UVA; 340-400 nm) or ultraviolet-B (UVB; 280-390 nm) exposure in mouse models heterozygous for mutant Braf or homozygous for mutant Nras Tumor onset was accelerated by UVB, but not UVA, and the resulting melanomas contained recurrent mutations affecting the RING domain of MAP3K1 and Actin-binding domain of Filamin A. Melanomas from UVB-irradiated, Braf-mutant mice averaged twice as many single-nucleotide variants and five times as many dipyrimidine variants than tumors from similarly irradiated Nras-mutant mice. A mutational signature discovered in UVB-accelerated tumors mirrored COSMIC signatures associated with human skin cancer and was more prominent in Braf- than Nras-mutant murine melanomas. These data show that a single UVB exposure yields a greater burden of mutations in murine tumors driven by oncogenic Braf.
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Affiliation(s)
- Robert L Bowman
- Human Oncology and Pathogenesis Program, Memorial Sloan Kettering Cancer Center, New York, NY, USA
| | - Rebecca C Hennessey
- Department of Cancer Biology and Genetics, The Ohio State University, Columbus, OH, USA
| | - Tirzah J Weiss
- Department of Cancer Biology and Genetics, The Ohio State University, Columbus, OH, USA
| | - David A Tallman
- Department of Cancer Biology and Genetics, The Ohio State University, Columbus, OH, USA
| | - Emma R Crawford
- Department of Molecular Genetics, The Ohio State University, Columbus, OH, USA
| | - Brandon M Murphy
- Department of Cancer Biology and Genetics, The Ohio State University, Columbus, OH, USA
| | - Amy Webb
- Department of Biomedical Informatics, The Ohio State University, Columbus, OH, USA
| | - Souhui Zhang
- Department of Cancer Biology and Genetics, The Ohio State University, Columbus, OH, USA
| | - Krista Md La Perle
- Department of Veterinary Biosciences, The Ohio State University, Columbus, OH, USA
| | - Craig J Burd
- Department of Molecular Genetics, The Ohio State University, Columbus, OH, USA
| | - Ross L Levine
- Human Oncology and Pathogenesis Program, Memorial Sloan Kettering Cancer Center, New York, NY, USA
| | - A Hunter Shain
- Department of Dermatology, Helen Diller Family Comprehensive Cancer Center, University of California, San Francisco, San Francisco, CA, USA
| | - Christin E Burd
- Department of Cancer Biology and Genetics, The Ohio State University, Columbus, OH, USA
- Department of Molecular Genetics, The Ohio State University, Columbus, OH, USA
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Zhou J, Kang X, An H, Lv Y, Liu X. The function and pathogenic mechanism of filamin A. Gene 2021; 784:145575. [PMID: 33737122 DOI: 10.1016/j.gene.2021.145575] [Citation(s) in RCA: 37] [Impact Index Per Article: 12.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/11/2020] [Revised: 03/04/2021] [Accepted: 03/08/2021] [Indexed: 12/13/2022]
Abstract
Filamin A(FLNa) is an actin-binding protein, which participates in the formation of the cytoskeleton, anchors a variety of proteins in the cytoskeleton and regulates cell adhesion and migration. It is involved in signal transduction, cell proliferation and differentiation, pseudopodia formation, vesicle transport, tumor resistance and genetic diseases by binding with interacting proteins. In order to fully elucidate the structure, function and pathogenesis of FLNa, we summarized all substances which directly or indirectly act on FLNa so far, upstream and downstream targets which having effect on it, signaling pathways and their functions. It also recorded the expression and effect of FLNa in different diseases, including hereditary disease and tumors.
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Affiliation(s)
- Jie Zhou
- Department of Oncology, Xiang'an Hospital of Xiamen University, School of Medicine, Xiamen University, Xiamen 361000, Fujian, China.
| | - Xinmei Kang
- Department of Oncology, Xiang'an Hospital of Xiamen University, School of Medicine, Xiamen University, Xiamen 361000, Fujian, China.
| | - Hanxiang An
- Department of Oncology, Xiang'an Hospital of Xiamen University, School of Medicine, Xiamen University, Xiamen 361000, Fujian, China.
| | - Yun Lv
- Department of Oncology, Xiang'an Hospital of Xiamen University, School of Medicine, Xiamen University, Xiamen 361000, Fujian, China.
| | - Xin Liu
- Department of Oncology, Xiang'an Hospital of Xiamen University, School of Medicine, Xiamen University, Xiamen 361000, Fujian, China.
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Iqbal NS, Jascur TA, Harrison SM, Edwards AB, Smith LT, Choi ES, Arevalo MK, Chen C, Zhang S, Kern AJ, Scheuerle AE, Sanchez EJ, Xing C, Baker LA. Prune belly syndrome in surviving males can be caused by Hemizygous missense mutations in the X-linked Filamin A gene. BMC MEDICAL GENETICS 2020; 21:38. [PMID: 32085749 PMCID: PMC7035669 DOI: 10.1186/s12881-020-0973-x] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 03/27/2019] [Accepted: 02/12/2020] [Indexed: 12/12/2022]
Abstract
Background Prune belly syndrome (PBS) is a rare, multi-system congenital myopathy primarily affecting males that is poorly described genetically. Phenotypically, its morbidity spans from mild to lethal, however, all isolated PBS cases manifest three cardinal pathological features: 1) wrinkled flaccid ventral abdominal wall with skeletal muscle deficiency, 2) urinary tract dilation with poorly contractile smooth muscle, and 3) intra-abdominal undescended testes. Despite evidence for a genetic basis, previously reported PBS autosomal candidate genes only account for one consanguineous family and single cases. Methods We performed whole exome sequencing (WES) of two maternal adult half-brothers with syndromic PBS (PBS + Otopalatodigital spectrum disorder [OPDSD]) and two unrelated sporadic individuals with isolated PBS and further functionally validated the identified mutations. Results We identified three unreported hemizygous missense point mutations in the X-chromosome gene Filamin A (FLNA) (c.4952 C > T (p.A1448V), c.6727C > T (p.C2160R), c.5966 G > A (p.G2236E)) in two related cases and two unrelated sporadic individuals. Two of the three PBS mutations map to the highly regulatory, stretch-sensing Ig19–21 region of FLNA and enhance binding to intracellular tails of the transmembrane receptor β-integrin 1 (ITGβ1). Conclusions FLNA is a regulatory actin-crosslinking protein that functions in smooth muscle cells as a mechanosensing molecular scaffold, transmitting force signals from the actin-myosin motor units and cytoskeleton via binding partners to the extracellular matrix. This is the first evidence for an X-linked cause of PBS in multiple unrelated individuals and expands the phenotypic spectrum associated with FLNA in males surviving even into adulthood.
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Affiliation(s)
- Nida S Iqbal
- Department of Urology, University of Texas Southwestern Medical Center, 5323 Harry Hines Blvd, Dallas, TX, 75390, USA.
| | - Thomas A Jascur
- Department of Urology, University of Texas Southwestern Medical Center, 5323 Harry Hines Blvd, Dallas, TX, 75390, USA
| | - Steven M Harrison
- Department of Urology, University of Texas Southwestern Medical Center, 5323 Harry Hines Blvd, Dallas, TX, 75390, USA.,Broad Institute of MIT and Harvard, Cambridge, MA, USA
| | - Angelena B Edwards
- Department of Urology, University of Texas Southwestern Medical Center, 5323 Harry Hines Blvd, Dallas, TX, 75390, USA
| | - Luke T Smith
- Department of Urology, University of Texas Southwestern Medical Center, 5323 Harry Hines Blvd, Dallas, TX, 75390, USA
| | - Erin S Choi
- Department of Urology, University of Texas Southwestern Medical Center, 5323 Harry Hines Blvd, Dallas, TX, 75390, USA
| | - Michelle K Arevalo
- Department of Urology, University of Texas Southwestern Medical Center, 5323 Harry Hines Blvd, Dallas, TX, 75390, USA
| | - Catherine Chen
- Department of Urology, University of Texas Southwestern Medical Center, 5323 Harry Hines Blvd, Dallas, TX, 75390, USA
| | - Shaohua Zhang
- Department of Urology, University of Texas Southwestern Medical Center, 5323 Harry Hines Blvd, Dallas, TX, 75390, USA
| | - Adam J Kern
- Department of Urology, University of Texas Southwestern Medical Center, 5323 Harry Hines Blvd, Dallas, TX, 75390, USA
| | - Angela E Scheuerle
- Department of Pediatrics, University of Texas Southwestern Medical Center, 5323 Harry Hines Blvd, Dallas, TX, 75390, USA.,McDermott Center for Human Growth and Development, Department of Bioinformatics, Department of Clinical Sciences, University of Texas Southwestern Medical Center, 5323 Harry Hines Blvd, Dallas, TX, 75390, USA
| | - Emma J Sanchez
- Department of Urology, University of Texas Southwestern Medical Center, 5323 Harry Hines Blvd, Dallas, TX, 75390, USA.,Children's Health Dallas, 2350 N. Stemmons Freeway, Suite F4300, Dallas, TX, 75207, USA
| | - Chao Xing
- McDermott Center for Human Growth and Development, Department of Bioinformatics, Department of Clinical Sciences, University of Texas Southwestern Medical Center, 5323 Harry Hines Blvd, Dallas, TX, 75390, USA
| | - Linda A Baker
- Department of Urology, University of Texas Southwestern Medical Center, 5323 Harry Hines Blvd, Dallas, TX, 75390, USA. .,Children's Health Dallas, 2350 N. Stemmons Freeway, Suite F4300, Dallas, TX, 75207, USA.
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Filamin A: key actor in platelet biology. Blood 2020; 134:1279-1288. [PMID: 31471375 DOI: 10.1182/blood.2019000014] [Citation(s) in RCA: 62] [Impact Index Per Article: 15.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/04/2019] [Accepted: 08/13/2019] [Indexed: 12/19/2022] Open
Abstract
Filamins (FLNs) are large dimeric actin-binding proteins that regulate actin cytoskeleton remodeling. In addition, FLNs serve as scaffolds for signaling proteins, such as tyrosine kinases, GTPases, or phosphatases, as well as for adhesive receptors, such as integrins. Thus, they connect adhesive receptors to signaling pathways and to cytoskeleton. There are 3 isoforms of FLN (filamin a [FLNa], FLNb, FLNc) that originate from 3 homologous genes. FLNa has been the recent focus of attention because its mutations are responsible for a wide spectrum of defects called filaminopathies A, affecting brain (peri-ventricular nodular heterotopia), heart (valve defect), skeleton, gastrointestinal tract, and, more recently, the megakaryocytic lineage. This review will focus on the physiological and pathological roles of FLNa in platelets. Indeed, FLNa mutations alter platelet production from their bone marrow precursors, the megakaryocytes, yielding giant platelets in reduced numbers (macrothrombocytopenia). In platelets per se, FLNa mutations may lead to impaired αIIbβ3 integrin activation or in contrast, increased αIIbβ3 activation, potentially enhancing the risk of thrombosis. Experimental work delineating the interaction of FLNa with its platelet partners, including αIIbβ3, the von Willebrand factor receptor GPIb-IX-V, the tyrosine kinase Syk, and the signaling pathway of the collagen receptor GPVI, will also be reviewed.
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Thieu T, Milman T, Bhatti TR, Eagle RC. Anterior Segment Dysgenesis With Accessory Iris Membranes in an Infant With Otopalatodigital Spectrum Disorder and Mutation in the FLNA Gene. J Pediatr Ophthalmol Strabismus 2020; 57:e8-e11. [PMID: 31978233 DOI: 10.3928/01913913-20191230-02] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/04/2019] [Accepted: 11/05/2019] [Indexed: 11/20/2022]
Abstract
A 4-month-old male infant with frontometaphyseal dysplasia and de novo FLNA gene mutation died of complications of disease. Post-mortem examination revealed accessory iris membranes. This is the first report in the literature of accessory iris membranes in a confirmed case of FLNA mutation and phenotypic anomalies consistent with frontometaphyseal dysplasia. [J Pediatr Ophthalmol Strabismus. 2020;57:e8-e11.].
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Joo S, Kim S, Seo H, Kim KJ. Crystal Structure of Amylomaltase from Corynebacterium glutamicum. JOURNAL OF AGRICULTURAL AND FOOD CHEMISTRY 2016; 64:5662-5670. [PMID: 27366969 DOI: 10.1021/acs.jafc.6b02296] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/06/2023]
Abstract
Amylomaltase is an essential enzyme in maltose utilization and maltodextrin metabolism, and it has been industrially used for the production of cyclodextrin and modification of starch. We determined the crystal structure of amylomaltase from Corynebacterium glutamicum (CgAM) at a resolution of 1.7 Å. Although CgAM forms a dimer without NaCl, it exists as a monomer in physiological concentration of NaCl. CgAM is composed of N- and C-terminal domains, which can be further divided into two and four subdomains, respectively. It exhibits a unique structural feature at the functionally unknown N-domain and also shows two striking differences at the C-domain compared to other amylomaltases. These differences at extended edge of the substrate-binding site might affect substrate specificity for large cyclodextrin formation. The bis-tris methane and sulfate molecules bound at the substrate-binding site of our current structure mimic the binding of the hydroxyl groups of glucose bound at subsites -1 and -2, respectively.
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Affiliation(s)
- Seongjoon Joo
- Structural and Molecular Biology Laboratory, School of Life Sciences and Biotechnology, Kyungpook National University , Daehak-ro 80, Buk-ku, Daegu 702-701, Republic of Korea
| | - Sangwoo Kim
- Structural and Molecular Biology Laboratory, School of Life Sciences and Biotechnology, Kyungpook National University , Daehak-ro 80, Buk-ku, Daegu 702-701, Republic of Korea
- School of Nano-Bioscience and Chemical Engineering, Ulsan National Institute of Science and Technology (UNIST) , Ulsan, 689-798, Republic of Korea
| | - Hogyun Seo
- Structural and Molecular Biology Laboratory, School of Life Sciences and Biotechnology, Kyungpook National University , Daehak-ro 80, Buk-ku, Daegu 702-701, Republic of Korea
| | - Kyung-Jin Kim
- Structural and Molecular Biology Laboratory, School of Life Sciences and Biotechnology, Kyungpook National University , Daehak-ro 80, Buk-ku, Daegu 702-701, Republic of Korea
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Filamin A interaction with the CXCR4 third intracellular loop regulates endocytosis and signaling of WT and WHIM-like receptors. Blood 2014; 125:1116-25. [PMID: 25355818 DOI: 10.1182/blood-2014-09-601807] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022] Open
Abstract
Warts, hypogammaglobulinemia, infections, and myelokathexis (WHIM) syndrome is a rare congenital immunodeficiency often caused by mutations in the last 10 to 19 C-terminal amino acids of CXCR4. These mutations impair CXCR4 internalization and increase responsiveness to CXCL12. The CXCR4 C-terminal domain (C-tail) also has a binding site for the actin-binding protein filamin A (FLNA); it is not known whether FLNA binds to WHIM CXCR4 mutants or whether this interaction is implicated in the hyperfunction of these receptors. Here we show that, in addition to interacting with the CXCR4 C-tail, FLNA interacted with a region in the receptor third intracellular loop (ICL3) spanning amino acids 238 to 246. This interaction involved specific FLNA repeats and was sensitive to Rho kinase inhibition. Deletion of the 238-246 motif accelerated CXCL12-induced wild-type (WT) receptor endocytosis but enabled CXCL12-mediated endocytosis and normalized signaling by the WHIM-associated receptor CXCR4(R334X). CXCL12 stimulation triggered CXCR4(R334X) internalization in FLNA-deficient M2 cells but not in the FLNA-expressing M2 subclone A7; this suggests a role for FLNA in stabilization of WHIM-like CXCR4 at the cell surface. FLNA increased β-arrestin2 binding to CXCR4(R334X) in vivo, which provides a molecular basis for FLNA-mediated hyperactivation of WHIM receptor signaling. We propose that FLNA interaction with ICL3 is central for endocytosis and signaling of WT and WHIM-like CXCR4 receptors.
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Morikawa K, Gouttenoire J, Hernandez C, Dao Thi VL, Tran HTL, Lange CM, Dill MT, Heim MH, Donzé O, Penin F, Quadroni M, Moradpour D. Quantitative proteomics identifies the membrane-associated peroxidase GPx8 as a cellular substrate of the hepatitis C virus NS3-4A protease. Hepatology 2014; 59:423-33. [PMID: 23929719 DOI: 10.1002/hep.26671] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/23/2013] [Accepted: 07/30/2013] [Indexed: 12/31/2022]
Abstract
UNLABELLED The hepatitis C virus (HCV) NS3-4A protease is not only an essential component of the viral replication complex and a prime target for antiviral intervention but also a key player in the persistence and pathogenesis of HCV. It cleaves and thereby inactivates two crucial adaptor proteins in viral RNA sensing and innate immunity, mitochondrial antiviral signaling protein (MAVS) and TRIF, a phosphatase involved in growth factor signaling, T-cell protein tyrosine phosphatase (TC-PTP), and the E3 ubiquitin ligase component UV-damaged DNA-binding protein 1 (DDB1). Here we explored quantitative proteomics to identify novel cellular substrates of the NS3-4A protease. Cell lines inducibly expressing the NS3-4A protease were analyzed by stable isotopic labeling using amino acids in cell culture (SILAC) coupled with protein separation and mass spectrometry. This approach identified the membrane-associated peroxidase GPx8 as a bona fide cellular substrate of the HCV NS3-4A protease. Cleavage by NS3-4A occurs at Cys 11, removing the cytosolic tip of GPx8, and was observed in different experimental systems as well as in liver biopsies from patients with chronic HCV. Overexpression and RNA silencing studies revealed that GPx8 is involved in viral particle production but not in HCV entry or RNA replication. CONCLUSION We provide proof-of-concept for the use of quantitative proteomics to identify cellular substrates of a viral protease and describe GPx8 as a novel proviral host factor targeted by the HCV NS3-4A protease.
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Affiliation(s)
- Kenichi Morikawa
- From the Division of Gastroenterology and Hepatology, Centre Hospitalier Universitaire Vaudois, Lausanne, Switzerland
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Suphamungmee W, Nakamura F, Hartwig JH, Lehman W. Electron microscopy and 3D reconstruction reveals filamin Ig domain binding to F-actin. J Mol Biol 2012; 424:248-56. [PMID: 23041423 DOI: 10.1016/j.jmb.2012.09.025] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/14/2012] [Revised: 09/24/2012] [Accepted: 09/28/2012] [Indexed: 11/24/2022]
Abstract
Filamin A (FLNa) is an actin-binding protein that cross-links F-actin into networks of orthogonally branched filaments. FLNa also directs the networks to integrins while responding to mechanochemical signaling pathways. Flexible, 160-nm-long FLNa molecules are tail-to-tail dimers, each subunit of which contains an N-terminal calponin homology (CH)/actin-binding domain connected by a series of 24 immunoglobulin (Ig) repeats to a dimerization site at their C-terminal end. Whereas the contribution of the CH domains to F-actin affinity is weak (apparent K(a)~10(5)), the binding of the intact protein to F-actin is strong (apparent K(a)~10(8)), suggesting involvement of additional parts of the molecule in this association. Indeed, previous results indicate that Ig repeats along FLNa contribute significantly to the strength of the actin filament interaction. In the current study, we used electron microscopy and three-dimensional reconstruction to elucidate the structural basis of the Ig repeat-F-actin binding. We find that FLNa density is clearly delineated in reconstructions of F-actin complexed either with a four-Ig-repeat segment of FLNa containing Ig repeat 10 or with immunoglobulin-like filamin A repeat (IgFLNa)10 alone. The mass attributable to IgFLNa10 lies peripherally along the actin helix over the N-terminus of actin subdomain 1. The IgFLNa10 interaction appears to be specific, since no other individual Ig repeat or fragment of the FLNa molecule examined, besides ones with IgFLNa10 or CH domains, decorated F-actin filaments or were detected in reconstructions. We conclude that the combined interactions of CH domains and the IgFLNa10 repeat provide the binding strength of the whole FLNa molecule and propose a model for the association of IgFLNa10 on actin filaments.
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Affiliation(s)
- Worawit Suphamungmee
- Department of Physiology and Biophysics, Boston University School of Medicine, Boston, MA 02118, USA
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Sawyer GM, Sutherland-Smith AJ. Crystal structure of the filamin N-terminal region reveals a hinge between the actin binding and first repeat domains. J Mol Biol 2012; 424:240-7. [PMID: 23036857 DOI: 10.1016/j.jmb.2012.09.016] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/24/2012] [Accepted: 09/20/2012] [Indexed: 11/15/2022]
Abstract
The filamin proteins cross-link F-actin and interact with protein partners to integrate both extracellular and intracellular signalling events with the cytoskeleton and to provide mechanoprotection and sensing to cells. The filamins are large, flexible, multi-domain homodimers with the interactions between domains important for protein function. The crystal structure of the N-terminal region of filamin B, containing the actin binding domain (ABD) and the first filamin repeat (FR1) domain, reveals an extended two-domain conformation with no interaction between the ABD and FR1 other than the connecting linker region. The two FLNB347 structures in the crystallographic asymmetric unit exhibit differing relative domain orientations providing the first high-resolution structural characterisation of a filamin inter-domain conformational change. The structure reveals a new hinge in the linker region between ABD and FR1 that is ideally positioned to orient the ABD for actin binding and adds to the previously described hinge regions, hinge 1 (between repeats 15 and 16) and hinge 2 (repeats 23 and 24), providing an additional mechanism by which filamin can exhibit inter-domain flexibility. The extended structure, with the absence of interactions between the domains, implies that any conformational rearrangements required for actin binding by the ABD, as observed for homologous proteins, can freely occur without being influenced by FR1. The ABD retains its previously observed compact conformation. FR1 exhibits a filamin immunoglobulin-like domain fold with a closed C-D β-strand groove, in contrast to filamin repeats that bind protein partners with this region of the domain surface.
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Affiliation(s)
- Gregory M Sawyer
- Institute of Molecular Biosciences, Massey University, Private Bag 11222, Palmerston North 4442, New Zealand
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