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Chehimi SN, Almeida VT, Nascimento AM, Zanardo ÉA, de Oliveira YG, Carvalho GFDS, Wolff BM, Montenegro MM, de Assunção NA, Kim CA, Kulikowski LD. Novel rearrangements between different chromosomes with direct impact on the diagnosis of 5p- syndrome. Clinics (Sao Paulo) 2022; 77:100045. [PMID: 35640457 PMCID: PMC9160337 DOI: 10.1016/j.clinsp.2022.100045] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/13/2021] [Accepted: 01/26/2022] [Indexed: 02/05/2023] Open
Abstract
OBJECTIVES Copy Number Variations (CNVs) in the human genome account for common populational variations but can also be responsible for genetic syndromes depending on the affected region. Although a deletion in 5p is responsible for a syndrome with highly recognizable phenotypical features, other chromosomal abnormalities might overlap phenotypes, especially considering that most studies in 5p use traditional cytogenetic techniques and not molecular techniques. METHODS The authors have investigated 29 patients with clinical suspicion of 5p- syndrome using Chromosomal Microarray (CMA), and have gathered information on previous tests, clinical signs, symptoms, and development of the patients. RESULTS The results showed 23 pure terminal deletions, one interstitial deletion, one deletion followed by a 3 Mb duplication in 5p, three cases of 5p deletion concomitant to duplications larger than 20 Mb in chromosomes 2, 9, and 18, and one 5p deletion with a chromosome Y deletion. CMA showed relevant CNVs not typically associated with 5p- that may have contributed to the final phenotype in these patients. CONCLUSIONS The authors have identified three novel rearrangements between chromosomes 5 and 2 (Patient 27), 5 and 18 (Patient 11), and 5 and Y (Patient 22), with breakpoints and overlapped phenotypes that were not previously described. The authors also highlight the need for further molecular investigation using CMA, in different chromosomes beyond chromosome 5 (since those cases did not show only the typical deletion expected for the 5p- syndrome) to explain discordant chromosomal features and overlapped phenotypes to unravel the cause of the syndrome in atypical cases.
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Affiliation(s)
- Samar Nasser Chehimi
- Laboratório de Citogenômica, Departmento de Patologia, Faculdade de Medicina, Universidade de São Paulo (FMUSP), São Paulo, SP, Brazil; Unidade de Genética, Departamento de Pediatria, Instituto da Criança, Hospital das Clínicas, Faculdade de Medicina, Universidade de São Paulo (HCFMUSP), São Paulo, SP, Brazil.
| | - Vanessa Tavares Almeida
- Laboratório de Citogenômica, Departmento de Patologia, Faculdade de Medicina, Universidade de São Paulo (FMUSP), São Paulo, SP, Brazil
| | - Amom Mendes Nascimento
- Laboratório de Citogenômica, Departmento de Patologia, Faculdade de Medicina, Universidade de São Paulo (FMUSP), São Paulo, SP, Brazil; Unidade de Genética, Departamento de Pediatria, Instituto da Criança, Hospital das Clínicas, Faculdade de Medicina, Universidade de São Paulo (HCFMUSP), São Paulo, SP, Brazil
| | - Évelin Aline Zanardo
- Laboratório de Citogenômica, Departmento de Patologia, Faculdade de Medicina, Universidade de São Paulo (FMUSP), São Paulo, SP, Brazil
| | - Yanca Gasparini de Oliveira
- Laboratório de Citogenômica, Departmento de Patologia, Faculdade de Medicina, Universidade de São Paulo (FMUSP), São Paulo, SP, Brazil
| | | | - Beatriz Martins Wolff
- Laboratório de Citogenômica, Departmento de Patologia, Faculdade de Medicina, Universidade de São Paulo (FMUSP), São Paulo, SP, Brazil
| | - Marilia Moreira Montenegro
- Laboratório de Citogenômica, Departmento de Patologia, Faculdade de Medicina, Universidade de São Paulo (FMUSP), São Paulo, SP, Brazil
| | - Nilson Antônio de Assunção
- Escola Paulista de Medicina, Universidade Federal de São Paulo, São Paulo, SP, Brazil; Departamento de Química, Instituto de Ciências Ambientais, Químicas e Farmacêuticas, Universidade Federal de São Paulo, Diadema, SP, Brazil
| | - Chong Ae Kim
- Unidade de Genética, Departamento de Pediatria, Instituto da Criança, Hospital das Clínicas, Faculdade de Medicina, Universidade de São Paulo (HCFMUSP), São Paulo, SP, Brazil
| | - Leslie Domenici Kulikowski
- Laboratório de Citogenômica, Departmento de Patologia, Faculdade de Medicina, Universidade de São Paulo (FMUSP), São Paulo, SP, Brazil; Unidade de Genética, Departamento de Pediatria, Instituto da Criança, Hospital das Clínicas, Faculdade de Medicina, Universidade de São Paulo (HCFMUSP), São Paulo, SP, Brazil
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Duman JG, Blanco FA, Cronkite CA, Ru Q, Erikson KC, Mulherkar S, Saifullah AB, Firozi K, Tolias KF. Rac-maninoff and Rho-vel: The symphony of Rho-GTPase signaling at excitatory synapses. Small GTPases 2022; 13:14-47. [PMID: 33955328 PMCID: PMC9707551 DOI: 10.1080/21541248.2021.1885264] [Citation(s) in RCA: 8] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/28/2020] [Revised: 01/22/2021] [Accepted: 01/28/2021] [Indexed: 01/15/2023] Open
Abstract
Synaptic connections between neurons are essential for every facet of human cognition and are thus regulated with extreme precision. Rho-family GTPases, molecular switches that cycle between an active GTP-bound state and an inactive GDP-bound state, comprise a critical feature of synaptic regulation. Rho-GTPases are exquisitely controlled by an extensive suite of activators (GEFs) and inhibitors (GAPs and GDIs) and interact with many different signalling pathways to fulfill their roles in orchestrating the development, maintenance, and plasticity of excitatory synapses of the central nervous system. Among the mechanisms that control Rho-GTPase activity and signalling are cell surface receptors, GEF/GAP complexes that tightly regulate single Rho-GTPase dynamics, GEF/GAP and GEF/GEF functional complexes that coordinate multiple Rho-family GTPase activities, effector positive feedback loops, and mutual antagonism of opposing Rho-GTPase pathways. These complex regulatory mechanisms are employed by the cells of the nervous system in almost every step of development, and prominently figure into the processes of synaptic plasticity that underlie learning and memory. Finally, misregulation of Rho-GTPases plays critical roles in responses to neuronal injury, such as traumatic brain injury and neuropathic pain, and in neurodevelopmental and neurodegenerative disorders, including intellectual disability, autism spectrum disorder, schizophrenia, and Alzheimer's Disease. Thus, decoding the mechanisms of Rho-GTPase regulation and function at excitatory synapses has great potential for combatting many of the biggest current challenges in mental health.
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Affiliation(s)
- Joseph G. Duman
- Department of Neuroscience, Baylor College of Medicine, Houston, TX, USA
| | - Francisco A. Blanco
- Department of Neuroscience, Baylor College of Medicine, Houston, TX, USA
- Integrative Molecular and Biomedical Science Graduate Program, Baylor College of Medicine, Houston, TX, USA
| | - Christopher A. Cronkite
- Verna and Marrs McLean Department of Biochemistry and Molecular Biology, Baylor College of Medicine, Houston, TX, USA
- Medical Scientist Training Program, Baylor College of Medicine, Houston, TX, USA
| | - Qin Ru
- Department of Neuroscience, Baylor College of Medicine, Houston, TX, USA
| | - Kelly C. Erikson
- Department of Neuroscience, Baylor College of Medicine, Houston, TX, USA
| | - Shalaka Mulherkar
- Department of Neuroscience, Baylor College of Medicine, Houston, TX, USA
| | - Ali Bin Saifullah
- Department of Neuroscience, Baylor College of Medicine, Houston, TX, USA
| | - Karen Firozi
- Department of Neuroscience, Baylor College of Medicine, Houston, TX, USA
| | - Kimberley F. Tolias
- Department of Neuroscience, Baylor College of Medicine, Houston, TX, USA
- Verna and Marrs McLean Department of Biochemistry and Molecular Biology, Baylor College of Medicine, Houston, TX, USA
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Wang J, Yuan L, Xu X, Zhang Z, Ma Y, Hong L, Ma J. Rho-GEF Trio regulates osteosarcoma progression and osteogenic differentiation through Rac1 and RhoA. Cell Death Dis 2021; 12:1148. [PMID: 34893584 PMCID: PMC8664940 DOI: 10.1038/s41419-021-04448-3] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/23/2021] [Revised: 11/23/2021] [Accepted: 12/02/2021] [Indexed: 11/08/2022]
Abstract
Osteosarcoma (OS) is the most common primary bone tumor. Its high mortality rate and metastasis rate seriously threaten human health. Currently, the treatment has reached a plateau, hence we urgently need to explore new therapeutic directions. In this paper, we found that Trio was highly expressed in osteosarcoma than normal tissues and promoted the proliferation, migration, and invasion of osteosarcoma cells. Furthermore, Trio inhibited osteosarcoma cells' osteogenic differentiation in vitro and accelerated the growth of osteosarcoma in vivo. Given Trio contains two GEF domains, which have been reported as the regulators of RhoGTPases, we further discovered that Trio could regulate osteosarcoma progression and osteogenic differentiation through activating RhoGTPases. In summary, all our preliminary results showed that Trio could be a potential target and prognostic marker of osteosarcoma.
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Affiliation(s)
- Junyi Wang
- Jiangsu Key Laboratory of Oral Diseases, Nanjing Medical University, 140 Hanzhong Road, 210029, Nanjing, China
| | - Lichan Yuan
- Jiangsu Key Laboratory of Oral Diseases, Nanjing Medical University, 140 Hanzhong Road, 210029, Nanjing, China
| | - Xiaohong Xu
- Jiangsu Key Laboratory of Oral Diseases, Nanjing Medical University, 140 Hanzhong Road, 210029, Nanjing, China
| | - Zhongyin Zhang
- Jiangsu Key Laboratory of Oral Diseases, Nanjing Medical University, 140 Hanzhong Road, 210029, Nanjing, China
| | - Yuhuan Ma
- Nanjing Foreign Language School, 210008, Nanjing, Jiangsu, China
| | - Leilei Hong
- Jiangsu Key Laboratory of Oral Diseases, Nanjing Medical University, 140 Hanzhong Road, 210029, Nanjing, China
| | - Junqing Ma
- Jiangsu Key Laboratory of Oral Diseases, Nanjing Medical University, 140 Hanzhong Road, 210029, Nanjing, China.
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Guo S, Meng L, Liu H, Yuan L, Zhao N, Ni J, Zhang Y, Ben J, Li YP, Ma J. Trio cooperates with Myh9 to regulate neural crest-derived craniofacial development. Am J Cancer Res 2021; 11:4316-4334. [PMID: 33754063 PMCID: PMC7977452 DOI: 10.7150/thno.51745] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/09/2020] [Accepted: 02/07/2021] [Indexed: 02/06/2023] Open
Abstract
Trio is a unique member of the Rho-GEF family that has three catalytic domains and is vital for various cellular processes in both physiological and developmental settings. TRIO mutations in humans are involved in craniofacial abnormalities, in which patients present with mandibular retrusion. However, little is known about the molecular mechanisms of Trio in neural crest cell (NCC)-derived craniofacial development, and there is still a lack of direct evidence to assign a functional role to Trio in NCC-induced craniofacial abnormalities. Methods: In vivo, we used zebrafish and NCC-specific knockout mouse models to investigate the phenotype and dynamics of NCC development in Trio morphants. In vitro, iTRAQ, GST pull-down assays, and proximity ligation assay (PLA) were used to explore the role of Trio and its potential downstream mediators in NCC migration and differentiation. Results: In zebrafish and mouse models, disruption of Trio elicited a migration deficit and impaired the differentiation of NCC derivatives, leading to craniofacial growth deficiency and mandibular retrusion. Moreover, Trio positively regulated Myh9 expression and directly interacted with Myh9 to coregulate downstream cellular signaling in NCCs. We further demonstrated that disruption of Trio or Myh9 inhibited Rac1 and Cdc42 activity, specifically affecting the nuclear export of β-catenin and NCC polarization. Remarkably, craniofacial abnormalities caused by trio deficiency in zebrafish could be partially rescued by the injection of mRNA encoding myh9, ca-Rac1, or ca-Cdc42. Conclusions: Here, we identified that Trio, interacting mostly with Myh9, acts as a key regulator of NCC migration and differentiation during craniofacial development. Our results indicate that trio morphant zebrafish and Wnt1-cre;Triofl/fl mice offer potential model systems to facilitate the study of the pathogenic mechanisms of Trio mutations causing craniofacial abnormalities.
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Schultz-Rogers L, Muthusamy K, Pinto E Vairo F, Klee EW, Lanpher B. Novel loss-of-function variants in TRIO are associated with neurodevelopmental disorder: case report. BMC MEDICAL GENETICS 2020; 21:219. [PMID: 33167890 PMCID: PMC7654171 DOI: 10.1186/s12881-020-01159-y] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 07/23/2020] [Accepted: 10/28/2020] [Indexed: 01/24/2023]
Abstract
Background Damaging variants in TRIO have been associated with moderate to severe neurodevelopmental disorders in humans. While recent work has delineated the positional effect of missense variation on the resulting phenotype, the clinical spectrum associated with loss-of-function variation has yet to be fully defined. Case presentation We report on two probands with novel loss-of-function variants in TRIO. Patient 1 presents with a severe neurodevelopmental disorder and macrocephaly. The TRIO variant is inherited from his affected mother. Patient 2 presents with moderate developmental delays, microcephaly, and cutis aplasia with a frameshift variant of unknown inheritance. Conclusions We describe two patients with neurodevelopmental disorder, macro/microcephaly, and cutis aplasia in one patient. Both patients have loss-of-function variants, helping to further characterize how these types of variants affect the phenotypic spectrum associated with TRIO. We also present the third reported case of autosomal dominant inheritance of a damaging variant in TRIO.
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Affiliation(s)
| | | | - Filippo Pinto E Vairo
- Center for Individualized Medicine, Mayo Clinic, Rochester, MN, USA.,Department of Clinical Genomics, Mayo Clinic, Rochester, MN, USA
| | - Eric W Klee
- Center for Individualized Medicine, Mayo Clinic, Rochester, MN, USA.,Department of Clinical Genomics, Mayo Clinic, Rochester, MN, USA
| | - Brendan Lanpher
- Department of Clinical Genomics, Mayo Clinic, Rochester, MN, USA.
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Gu J, Yang Z, Yuan L, Guo S, Wang D, Zhao N, Meng L, Liu H, Chen W, Ma J. Rho-GEF trio regulates osteoclast differentiation and function by Rac1/Cdc42. Exp Cell Res 2020; 396:112265. [PMID: 32898553 DOI: 10.1016/j.yexcr.2020.112265] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/06/2020] [Revised: 08/31/2020] [Accepted: 09/02/2020] [Indexed: 01/09/2023]
Abstract
Many bone diseases result from abnormal bone resorption by osteoclasts (OCs). Studying OC related regulatory genes is necessary for the development of new therapeutic strategies. Rho GTPases have been proven to regulate OC differentiation and function and only mature OCs can carry out bone resorption. Here we demonstrate that Rac1 and Cdc42 exchange factor Triple functional domain (Trio) is critical for bone resorption caused by OCs. In this study, we created LysM-Cre;Triofl/fl conditional knockout mice in which Trio was conditionally ablated in monocytes. LysM-Cre;Triofl/fl mice showed increased bone mass due to impaired bone resorption caused by OCs. Furthermore, our in vitro analysis indicated that Trio conditional deficiency significantly suppressed OC differentiation and function. At the molecular level, Trio deficiency significantly inhibited the expression of genes critical for osteoclastogenesis and OC function. Mechanistically, our researches suggested that perturbed Rac1/Cdc42-PAK1-ERK/p38 signaling could be used to explain the lower ability of bone resorption in CKO mice. Taken together, this study indicates that Trio is a regulator of OCs. Studying the role of Trio in OCs provides a potential new insight for the treatment of OC related bone diseases.
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Affiliation(s)
- Jiawen Gu
- Jiangsu Key Laboratory of Oral Diseases, Nanjing Medical University, 140 Hanzhong Road, Nanjing, 210029, China; Department of Orthodontics, Affiliated Hospital of Stomatology, Nanjing Medical University, 140 Hanzhong Road, Nanjing, 210029, China
| | - Zhiwen Yang
- Jiangsu Key Laboratory of Oral Diseases, Nanjing Medical University, 140 Hanzhong Road, Nanjing, 210029, China; Department of Orthodontics, Affiliated Hospital of Stomatology, Nanjing Medical University, 140 Hanzhong Road, Nanjing, 210029, China
| | - Lichan Yuan
- Jiangsu Key Laboratory of Oral Diseases, Nanjing Medical University, 140 Hanzhong Road, Nanjing, 210029, China; Department of Orthodontics, Affiliated Hospital of Stomatology, Nanjing Medical University, 140 Hanzhong Road, Nanjing, 210029, China
| | - Shuyu Guo
- Jiangsu Key Laboratory of Oral Diseases, Nanjing Medical University, 140 Hanzhong Road, Nanjing, 210029, China; Department of Orthodontics, Affiliated Hospital of Stomatology, Nanjing Medical University, 140 Hanzhong Road, Nanjing, 210029, China
| | - Dan Wang
- Department of Stomatatology, Lianshui County People's Hospital, Kangda College of Nanjing Medical University, Huai'an, 223400, China
| | - Na Zhao
- Jiangsu Key Laboratory of Oral Diseases, Nanjing Medical University, 140 Hanzhong Road, Nanjing, 210029, China; Department of Orthodontics, Affiliated Hospital of Stomatology, Nanjing Medical University, 140 Hanzhong Road, Nanjing, 210029, China
| | - Li Meng
- Jiangsu Key Laboratory of Oral Diseases, Nanjing Medical University, 140 Hanzhong Road, Nanjing, 210029, China; Department of Orthodontics, Affiliated Hospital of Stomatology, Nanjing Medical University, 140 Hanzhong Road, Nanjing, 210029, China
| | - Haojie Liu
- Jiangsu Key Laboratory of Oral Diseases, Nanjing Medical University, 140 Hanzhong Road, Nanjing, 210029, China; Department of Orthodontics, Affiliated Hospital of Stomatology, Nanjing Medical University, 140 Hanzhong Road, Nanjing, 210029, China
| | - Wenjing Chen
- Jiangsu Key Laboratory of Oral Diseases, Nanjing Medical University, 140 Hanzhong Road, Nanjing, 210029, China; Department of Orthodontics, Affiliated Hospital of Stomatology, Nanjing Medical University, 140 Hanzhong Road, Nanjing, 210029, China
| | - Junqing Ma
- Jiangsu Key Laboratory of Oral Diseases, Nanjing Medical University, 140 Hanzhong Road, Nanjing, 210029, China; Department of Orthodontics, Affiliated Hospital of Stomatology, Nanjing Medical University, 140 Hanzhong Road, Nanjing, 210029, China.
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Corrêa T, Poswar F, Feltes BC, Riegel M. Candidate Genes Associated With Neurological Findings in a Patient With Trisomy 4p16.3 and Monosomy 5p15.2. Front Genet 2020; 11:561. [PMID: 32625234 PMCID: PMC7311770 DOI: 10.3389/fgene.2020.00561] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/06/2019] [Accepted: 05/11/2020] [Indexed: 12/12/2022] Open
Abstract
In this report, we present a patient with brain alterations and dysmorphic features associated with chromosome duplication seen in 4p16.3 region and chromosomal deletion in a critical region responsible for Cri-du-chat syndrome (CdCS). Chromosomal microarray analysis (CMA) revealed a 41.1 Mb duplication encompassing the band region 4p16.3-p13, and a 14.7 Mb deletion located between the bands 5p15.33 and p15.1. The patient's clinical findings overlap with previously reported cases of chromosome 4p duplication syndrome and CdCS. The patient's symptoms are notably similar to those of CdCS patients as she presented with a weak, high-pitched voice and showed a similar pathogenicity observed in the brain MRI. These contiguous gene syndromes present with distinct clinical manifestations. However, the phenotypic and cytogenetic variability in affected individuals, such as the low frequency and the large genomic regions that can be altered, make it challenging to identify candidate genes that contribute to the pathogenesis of these syndromes. Therefore, systems biology and CMA techniques were used to investigate the extent of chromosome rearrangement on critical regions in our patient's phenotype. We identified the candidate genes PPARGC1A, CTBP1, TRIO, TERT, and CCT5 that are associated with the neuropsychomotor delay, microcephaly, and neurological alterations found in our patient. Through investigating pathways that associate with essential nodes in the protein interaction network, we discovered proteins involved in cellular differentiation and proliferation, as well as proteins involved in the formation and disposition of the cytoskeleton. The combination of our cytogenomic and bioinformatic analysis provided these possible explanations for the unique clinical phenotype, which has not yet been described in scientific literature.
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Affiliation(s)
- Thiago Corrêa
- Post-Graduate Program in Genetics and Molecular Biology, Genetics Department, Universidade Federal do Rio Grande do Sul, Porto Alegre, Brazil
| | - Fabiano Poswar
- Medical Genetics Service, Hospital de Clínicas de Porto Alegre, Porto Alegre, Brazil
| | - Bruno César Feltes
- Department of Theoritical Informatics, Institute of Informatics, Universidade Federal do Rio Grande do Sul, Porto Alegre, Brazil
| | - Mariluce Riegel
- Post-Graduate Program in Genetics and Molecular Biology, Genetics Department, Universidade Federal do Rio Grande do Sul, Porto Alegre, Brazil
- Medical Genetics Service, Hospital de Clínicas de Porto Alegre, Porto Alegre, Brazil
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Barbosa S, Greville-Heygate S, Bonnet M, Godwin A, Fagotto-Kaufmann C, Kajava AV, Laouteouet D, Mawby R, Wai HA, Dingemans AJ, Hehir-Kwa J, Willems M, Capri Y, Mehta SG, Cox H, Goudie D, Vansenne F, Turnpenny P, Vincent M, Cogné B, Lesca G, Hertecant J, Rodriguez D, Keren B, Burglen L, Gérard M, Putoux A, Cantagrel V, Siquier-Pernet K, Rio M, Banka S, Sarkar A, Steeves M, Parker M, Clement E, Moutton S, Tran Mau-Them F, Piton A, de Vries BB, Guille M, Debant A, Schmidt S, Baralle D, Baralle D. Opposite Modulation of RAC1 by Mutations in TRIO Is Associated with Distinct, Domain-Specific Neurodevelopmental Disorders. Am J Hum Genet 2020; 106:338-355. [PMID: 32109419 PMCID: PMC7058823 DOI: 10.1016/j.ajhg.2020.01.018] [Citation(s) in RCA: 49] [Impact Index Per Article: 12.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/11/2019] [Accepted: 01/27/2020] [Indexed: 12/13/2022] Open
Abstract
The Rho-guanine nucleotide exchange factor (RhoGEF) TRIO acts as a key regulator of neuronal migration, axonal outgrowth, axon guidance, and synaptogenesis by activating the GTPase RAC1 and modulating actin cytoskeleton remodeling. Pathogenic variants in TRIO are associated with neurodevelopmental diseases, including intellectual disability (ID) and autism spectrum disorders (ASD). Here, we report the largest international cohort of 24 individuals with confirmed pathogenic missense or nonsense variants in TRIO. The nonsense mutations are spread along the TRIO sequence, and affected individuals show variable neurodevelopmental phenotypes. In contrast, missense variants cluster into two mutational hotspots in the TRIO sequence, one in the seventh spectrin repeat and one in the RAC1-activating GEFD1. Although all individuals in this cohort present with developmental delay and a neuro-behavioral phenotype, individuals with a pathogenic variant in the seventh spectrin repeat have a more severe ID associated with macrocephaly than do most individuals with GEFD1 variants, who display milder ID and microcephaly. Functional studies show that the spectrin and GEFD1 variants cause a TRIO-mediated hyper- or hypo-activation of RAC1, respectively, and we observe a striking correlation between RAC1 activation levels and the head size of the affected individuals. In addition, truncations in TRIO GEFD1 in the vertebrate model X. tropicalis induce defects that are concordant with the human phenotype. This work demonstrates distinct clinical and molecular disorders clustering in the GEFD1 and seventh spectrin repeat domains and highlights the importance of tight control of TRIO-RAC1 signaling in neuronal development.
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Affiliation(s)
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | - Diana Baralle
- Wessex Clinical Genetics, University Hospital Southampton National Health Service Foundation Trust, Southampton SO16 5YA, UK; Human Development and Health, Faculty of Medicine, University of Southampton, Southampton SO16 6YD, UK.
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