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Báez-Flores J, Rodríguez-Martín M, Lacal J. The therapeutic potential of neurofibromin signaling pathways and binding partners. Commun Biol 2023; 6:436. [PMID: 37081086 PMCID: PMC10119308 DOI: 10.1038/s42003-023-04815-0] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/29/2022] [Accepted: 04/05/2023] [Indexed: 04/22/2023] Open
Abstract
Neurofibromin controls many cell processes, such as growth, learning, and memory. If neurofibromin is not working properly, it can lead to health problems, including issues with the nervous, skeletal, and cardiovascular systems and cancer. This review examines neurofibromin's binding partners, signaling pathways and potential therapeutic targets. In addition, it summarizes the different post-translational modifications that can affect neurofibromin's interactions with other molecules. It is essential to investigate the molecular mechanisms that underlie neurofibromin variants in order to provide with functional connections between neurofibromin and its associated proteins for possible therapeutic targets based on its biological function.
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Affiliation(s)
- Juan Báez-Flores
- Laboratory of Functional Genetics of Rare Diseases, Department of Microbiology and Genetics, University of Salamanca (USAL), 37007, Salamanca, Spain
- Institute of Biomedical Research of Salamanca (IBSAL), 37007, Salamanca, Spain
| | - Mario Rodríguez-Martín
- Laboratory of Functional Genetics of Rare Diseases, Department of Microbiology and Genetics, University of Salamanca (USAL), 37007, Salamanca, Spain
- Institute of Biomedical Research of Salamanca (IBSAL), 37007, Salamanca, Spain
| | - Jesus Lacal
- Laboratory of Functional Genetics of Rare Diseases, Department of Microbiology and Genetics, University of Salamanca (USAL), 37007, Salamanca, Spain.
- Institute of Biomedical Research of Salamanca (IBSAL), 37007, Salamanca, Spain.
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Functional Assays Combined with Pre-mRNA-Splicing Analysis Improve Variant Classification and Diagnostics for Individuals with Neurofibromatosis Type 1 and Legius Syndrome. Hum Mutat 2023. [DOI: 10.1155/2023/9628049] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/17/2023]
Abstract
Neurofibromatosis type 1 (NF1) and Legius syndrome (LS) are caused by inactivating variants in NF1 and SPRED1. NF1 encodes neurofibromin (NF), a GTPase-activating protein (GAP) for RAS that interacts with the SPRED1 product, Sprouty-related protein with an EVH (Ena/Vasp homology) domain 1 (SPRED1). Obtaining a clinical and molecular diagnosis of NF1 or LS can be challenging due to the phenotypic diversity, the size and complexity of the NF1 and SPRED1 loci, and uncertainty over the effects of some NF1 and SPRED1 variants on pre-mRNA splicing and/or protein expression and function. To improve NF1 and SPRED1 variant classification and establish pathogenicity for NF1 and SPRED1 variants identified in individuals with NF1 or LS, we analyzed patient RNA by RT-PCR and performed in vitro exon trap experiments and estimated NF and SPRED1 protein expression, RAS GAP activity, and interaction. We obtained evidence to support pathogenicity according to American College of Medical Genetics guidelines for 73/114 variants tested, demonstrating the utility of functional approaches for NF1 and SPRED1 variant classification and NF and LS diagnostics.
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Stella A, Lastella P, Viggiano L, Bagnulo R, Resta N. Clinical presentation and genetic analyses of neurofibromatosis type 1 in independent patients with monoallelic double de novo closely spaced mutations in the NF1 gene. Hum Mutat 2022; 43:1354-1360. [PMID: 35723633 PMCID: PMC9540858 DOI: 10.1002/humu.24423] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/04/2022] [Revised: 06/14/2022] [Accepted: 06/15/2022] [Indexed: 12/15/2022]
Abstract
Neurofibromatosis type 1 (NF1) belongs to RASopathies, a group of syndromes caused by germline mutations in Ras/MAPK pathway genes. Most NF1 patients exhibit single inactivating pathogenic variants within the NF1 gene. We performed extensive genetic analyses in two NF1 families disclosing the first two cases of double de novo monoallelic NF1 variants. Both index patients described in this study had classical NF1. Probands were born from fathers in their late 30s and presented closely spaced double mutations (<100 bp) in NF1 regions showing an excess of somatic mutations. Closely spaced multiple mutations have been reported in RAS/MAPK signaling genes but never in NF1. Mutagenesis is a quasi-random process in humans, therefore two causative variants in the same gene, moreover in the same allele are exceptional. Here, we discuss possible mechanisms for this ultrarare event. Our findings confirm the possibility of a higher risk of concurrent de novo variants in NF1.
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Affiliation(s)
- Alessandro Stella
- Department of Biomedical Sciences and Human OncologyLaboratory of Medical Genetics, Università di Bari Aldo MoroBariItaly
| | - Patrizia Lastella
- Rare Disease CenterInternal MedicineUnit ‘C. Frugoni’, AOU Policlinico di BariBariItaly
| | - Luigi Viggiano
- Department of BiologyUniversity of Bari Aldo MoroBariItaly
| | - Rosanna Bagnulo
- Department of Biomedical Sciences and Human OncologyLaboratory of Medical Genetics, Università di Bari Aldo MoroBariItaly
| | - Nicoletta Resta
- Department of Biomedical Sciences and Human OncologyLaboratory of Medical Genetics, Università di Bari Aldo MoroBariItaly
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Leier A, Moore M, Liu H, Daniel M, Hyde AM, Messiaen L, Korf BR, Selvakumaran J, Ciszewski L, Lambert L, Foote J, Wallace MR, Kesterson RA, Dickson G, Popplewell L, Wallis D. Targeted exon skipping of NF1 exon 17 as a therapeutic for neurofibromatosis type I. MOLECULAR THERAPY. NUCLEIC ACIDS 2022; 28:261-278. [PMID: 35433111 PMCID: PMC8983316 DOI: 10.1016/j.omtn.2022.03.011] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 07/28/2021] [Accepted: 03/12/2022] [Indexed: 12/14/2022]
Abstract
We investigated the feasibility of utilizing an exon-skipping approach as a genotype-dependent therapeutic for neurofibromatosis type 1 (NF1) by determining which NF1 exons might be skipped while maintaining neurofibromin protein expression and GTPase activating protein (GAP)-related domain (GRD) function. Initial in silico analysis predicted exons that can be skipped with minimal loss of neurofibromin function, which was confirmed by in vitro assessments utilizing an Nf1 cDNA-based functional screening system. Skipping of exons 17 or 52 fit our criteria, as minimal effects on protein expression and GRD activity were noted. Antisense phosphorodiamidate morpholino oligomers (PMOs) were utilized to skip exon 17 in human cell lines with patient-specific pathogenic variants in exon 17, c.1885G>A, and c.1929delG. PMOs restored functional neurofibromin expression. To determine the in vivo significance of exon 17 skipping, we generated a homozygous deletion of exon 17 in a novel mouse model. Mice were viable and exhibited a normal lifespan. Initial studies did not reveal the presence of tumor development; however, altered nesting behavior and systemic lymphoid hyperplasia was noted in peripheral lymphoid organs. Alterations in T and B cell frequencies in the thymus and spleen were identified. Hence, exon skipping should be further investigated as a therapeutic approach for NF1 patients with pathogenic variants in exon 17, as homozygous deletion of exon 17 is consistent with at least partial function of neurofibromin.
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Affiliation(s)
- André Leier
- Department of Genetics, University of Alabama at Birmingham, Birmingham, AL 35294, USA
| | - Marc Moore
- Centre of Biomedical Science, Department of Biological Sciences, Royal Holloway - University of London, Egham, Surrey TW20 0EX, UK
| | - Hui Liu
- Department of Genetics, University of Alabama at Birmingham, Birmingham, AL 35294, USA
| | - Michael Daniel
- Department of Genetics, University of Alabama at Birmingham, Birmingham, AL 35294, USA
| | - Alexis M. Hyde
- Department of Genetics, University of Alabama at Birmingham, Birmingham, AL 35294, USA
| | - Ludwine Messiaen
- Department of Genetics, University of Alabama at Birmingham, Birmingham, AL 35294, USA
| | - Bruce R. Korf
- Department of Genetics, University of Alabama at Birmingham, Birmingham, AL 35294, USA
| | - Jamuna Selvakumaran
- Centre of Biomedical Science, Department of Biological Sciences, Royal Holloway - University of London, Egham, Surrey TW20 0EX, UK
| | - Lukasz Ciszewski
- Centre of Biomedical Science, Department of Biological Sciences, Royal Holloway - University of London, Egham, Surrey TW20 0EX, UK
| | - Laura Lambert
- Department of Genetics, University of Alabama at Birmingham, Birmingham, AL 35294, USA
| | - Jeremy Foote
- Department of Microbiology, University of Alabama at Birmingham, Birmingham, AL 35294, USA
| | - Margaret R. Wallace
- Department of Molecular Genetics and Microbiology, and UF Health Cancer Center, University of Florida, Gainesville, FL 32611, USA
| | - Robert A. Kesterson
- Department of Genetics, University of Alabama at Birmingham, Birmingham, AL 35294, USA
| | - George Dickson
- Centre of Biomedical Science, Department of Biological Sciences, Royal Holloway - University of London, Egham, Surrey TW20 0EX, UK
| | - Linda Popplewell
- Centre of Biomedical Science, Department of Biological Sciences, Royal Holloway - University of London, Egham, Surrey TW20 0EX, UK
| | - Deeann Wallis
- Department of Genetics, University of Alabama at Birmingham, Birmingham, AL 35294, USA
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Awad EK, Moore M, Liu H, Ciszewski L, Lambert L, Korf BR, Popplewell L, Kesterson RA, Wallis D. Restoration of Normal NF1 Function with Antisense Morpholino Treatment of Recurrent Pathogenic Patient-Specific Variant c.1466A>G; p.Y489C. J Pers Med 2021; 11:jpm11121320. [PMID: 34945792 PMCID: PMC8705852 DOI: 10.3390/jpm11121320] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/07/2021] [Revised: 11/04/2021] [Accepted: 11/19/2021] [Indexed: 12/11/2022] Open
Abstract
Neurofibromatosis type 1 (NF1) is an autosomal dominant genetic disorder with almost 3000 different disease-causing variants within the NF1 gene identified. Up to 44% of these variants cause splicing errors to occur within pre-mRNA. A recurrent variant in exon 13, c.1466A>G; p.Y489C (Y489C) results in the creation of an intragenic cryptic splice site, aberrant splicing, a 62 base pair deletion from the mRNA, and subsequent frameshift. We investigated the ability of phosphorodiamidate morpholino oligomers (PMOs) to mask this variant on the RNA level, thus restoring normal splicing. To model this variant, we have developed a human iPS cell line homozygous for the variant using CRISPR/Cas9. PMOs were designed to be 25 base pairs long, and to cover the mutation site so it could not be read by splicing machinery. Results from our in vitro testing showed restoration of normal splicing in the RNA and restoration of full length neurofibromin protein. In addition, we observe the restoration of neurofibromin functionality through GTP-Ras and pERK/ERK testing. The results from this study demonstrate the ability of a PMO to correct splicing errors in NF1 variants at the RNA level, which could open the door for splicing corrections for other variants in this and a variety of diseases.
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Affiliation(s)
- Elias K. Awad
- Department of Genetics, University of Alabama at Birmingham, Birmingham, AL 35294, USA; (E.K.A.); (H.L.); (L.L.); (B.R.K.); (R.A.K.)
| | - Marc Moore
- Centre of Biomedical Sciences, Department of Biological Sciences, Royal Holloway, University of London, Egham, Surrey TW20 0EX, UK; (M.M.); (L.C.); (L.P.)
| | - Hui Liu
- Department of Genetics, University of Alabama at Birmingham, Birmingham, AL 35294, USA; (E.K.A.); (H.L.); (L.L.); (B.R.K.); (R.A.K.)
| | - Lukasz Ciszewski
- Centre of Biomedical Sciences, Department of Biological Sciences, Royal Holloway, University of London, Egham, Surrey TW20 0EX, UK; (M.M.); (L.C.); (L.P.)
| | - Laura Lambert
- Department of Genetics, University of Alabama at Birmingham, Birmingham, AL 35294, USA; (E.K.A.); (H.L.); (L.L.); (B.R.K.); (R.A.K.)
| | - Bruce R. Korf
- Department of Genetics, University of Alabama at Birmingham, Birmingham, AL 35294, USA; (E.K.A.); (H.L.); (L.L.); (B.R.K.); (R.A.K.)
| | - Linda Popplewell
- Centre of Biomedical Sciences, Department of Biological Sciences, Royal Holloway, University of London, Egham, Surrey TW20 0EX, UK; (M.M.); (L.C.); (L.P.)
| | - Robert A. Kesterson
- Department of Genetics, University of Alabama at Birmingham, Birmingham, AL 35294, USA; (E.K.A.); (H.L.); (L.L.); (B.R.K.); (R.A.K.)
| | - Deeann Wallis
- Department of Genetics, University of Alabama at Birmingham, Birmingham, AL 35294, USA; (E.K.A.); (H.L.); (L.L.); (B.R.K.); (R.A.K.)
- Correspondence: ; Tel.: +1-205-934-2794; Fax: +1-205-975-4418
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