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Scala M, Tomati V, Ferla M, Lena M, Cohen JS, Fatemi A, Brokamp E, Bican A, Phillips JA, Koziura ME, Nicouleau M, Rio M, Siquier K, Boddaert N, Musante I, Tamburro S, Baldassari S, Iacomino M, Scudieri P, Rosenfeld JA, Bellus G, Reed S, Al Saif H, Russo RS, Walsh MB, Cantagrel V, Crunk A, Gustincich S, Ruggiero SM, Fitzgerald MP, Helbig I, Striano P, Severino M, Salpietro V, Pedemonte N, Zara F. De novo variants in DENND5B cause a neurodevelopmental disorder. Am J Hum Genet 2024; 111:529-543. [PMID: 38387458 PMCID: PMC10940048 DOI: 10.1016/j.ajhg.2024.02.001] [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: 08/31/2023] [Revised: 01/30/2024] [Accepted: 02/01/2024] [Indexed: 02/24/2024] Open
Abstract
The Rab family of guanosine triphosphatases (GTPases) includes key regulators of intracellular transport and membrane trafficking targeting specific steps in exocytic, endocytic, and recycling pathways. DENND5B (Rab6-interacting Protein 1B-like protein, R6IP1B) is the longest isoform of DENND5, an evolutionarily conserved DENN domain-containing guanine nucleotide exchange factor (GEF) that is highly expressed in the brain. Through exome sequencing and international matchmaking platforms, we identified five de novo variants in DENND5B in a cohort of five unrelated individuals with neurodevelopmental phenotypes featuring cognitive impairment, dysmorphism, abnormal behavior, variable epilepsy, white matter abnormalities, and cortical gyration defects. We used biochemical assays and confocal microscopy to assess the impact of DENND5B variants on protein accumulation and distribution. Then, exploiting fluorescent lipid cargoes coupled to high-content imaging and analysis in living cells, we investigated whether DENND5B variants affected the dynamics of vesicle-mediated intracellular transport of specific cargoes. We further generated an in silico model to investigate the consequences of DENND5B variants on the DENND5B-RAB39A interaction. Biochemical analysis showed decreased protein levels of DENND5B mutants in various cell types. Functional investigation of DENND5B variants revealed defective intracellular vesicle trafficking, with significant impairment of lipid uptake and distribution. Although none of the variants affected the DENND5B-RAB39A interface, all were predicted to disrupt protein folding. Overall, our findings indicate that DENND5B variants perturb intracellular membrane trafficking pathways and cause a complex neurodevelopmental syndrome with variable epilepsy and white matter involvement.
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Affiliation(s)
- Marcello Scala
- Department of Neurosciences, Rehabilitation, Ophthalmology, Genetics, Maternal and Child Health, University of Genoa, Genoa, Italy; Pediatric Neurology and Muscular Diseases Unit, IRCCS Istituto Giannina Gaslini, Genoa, Italy; UOC Genetica Medica, IRCCS Giannina Gaslini, Genoa, Italy
| | - Valeria Tomati
- UOC Genetica Medica, IRCCS Giannina Gaslini, Genoa, Italy
| | - Matteo Ferla
- Oxford Protein Informatics Group, Department of Statistics, University of Oxford, Oxford, UK
| | - Mariateresa Lena
- Department of Neurosciences, Rehabilitation, Ophthalmology, Genetics, Maternal and Child Health, University of Genoa, Genoa, Italy
| | - Julie S Cohen
- Department of Neurology and Developmental Medicine, Kennedy Krieger Institute, Baltimore, MD, USA; Department of Neurology, Johns Hopkins University School of Medicine, Baltimore, MD, USA
| | - Ali Fatemi
- Department of Neurology and Developmental Medicine, Kennedy Krieger Institute, Baltimore, MD, USA; Department of Neurology, Johns Hopkins University School of Medicine, Baltimore, MD, USA
| | - Elly Brokamp
- Department of Pediatrics, Vanderbilt University Medical Center, Nashville, TN, USA
| | - Anna Bican
- Department of Pediatrics, Vanderbilt University Medical Center, Nashville, TN, USA
| | - John A Phillips
- Department of Pediatrics, Vanderbilt University Medical Center, Nashville, TN, USA
| | - Mary E Koziura
- Department of Pediatrics, Vanderbilt University Medical Center, Nashville, TN, USA
| | - Michael Nicouleau
- Université Paris Cité, Imagine Institute, Developmental Brain Disorders Laboratory, INSERM UMR 1163, 75015 Paris, France
| | - Marlene Rio
- Université Paris Cité, Imagine Institute, Developmental Brain Disorders Laboratory, INSERM UMR 1163, 75015 Paris, France; Service de Génétique, Necker Enfants Malades University Hospital, Assistance Publique-Hôpitaux de Pairs, Paris, France
| | - Karine Siquier
- Université Paris Cité, Imagine Institute, Developmental Brain Disorders Laboratory, INSERM UMR 1163, 75015 Paris, France
| | - Nathalie Boddaert
- Département de Radiologie Pédiatrique, INSERM UMR 1163 and INSERM U1000, AP-HP, Hôpital Necker-Enfants Malades, Paris, France
| | - Ilaria Musante
- UOC Genetica Medica, IRCCS Giannina Gaslini, Genoa, Italy
| | | | | | | | - Paolo Scudieri
- UOC Genetica Medica, IRCCS Giannina Gaslini, Genoa, Italy
| | - Jill A Rosenfeld
- Department of Molecular & Human Genetics, Baylor College of Medicine, Houston, TX, USA; Baylor Genetics Laboratories, Houston, TX, USA
| | - Gary Bellus
- Clinical Genetics, Geisinger Medical Center, Danville, PA 17822, USA
| | - Sara Reed
- Clinical Genetics, Geisinger Medical Center, Danville, PA 17822, USA
| | - Hind Al Saif
- Department of Human and Molecular Genetics, Division of Clinical Genetics, Virginia Commonwealth University School of Medicine, Richmond, VA, USA
| | | | - Matthew B Walsh
- Department of Human Genetics, Emory University, Atlanta, GA 30322, USA
| | - Vincent Cantagrel
- Université Paris Cité, Imagine Institute, Developmental Brain Disorders Laboratory, INSERM UMR 1163, 75015 Paris, France
| | | | - Stefano Gustincich
- Department of Neuroscience and Brain Technologies, Istituto Italiano di Tecnologia, 16163 Genoa, Italy
| | - Sarah M Ruggiero
- Division of Neurology, Children's Hospital of Philadelphia, Philadelphia, PA 19104, USA; The Epilepsy NeuroGenetics Initiative (ENGIN), Children's Hospital of Philadelphia, Philadelphia, PA, USA
| | - Mark P Fitzgerald
- Division of Neurology, Children's Hospital of Philadelphia, Philadelphia, PA 19104, USA; The Epilepsy NeuroGenetics Initiative (ENGIN), Children's Hospital of Philadelphia, Philadelphia, PA, USA; Department of Neurology, University of Pennsylvania, Perelman School of Medicine, Philadelphia, PA 19104, USA
| | - Ingo Helbig
- Division of Neurology, Children's Hospital of Philadelphia, Philadelphia, PA 19104, USA; The Epilepsy NeuroGenetics Initiative (ENGIN), Children's Hospital of Philadelphia, Philadelphia, PA, USA; Department of Neurology, University of Pennsylvania, Perelman School of Medicine, Philadelphia, PA 19104, USA; Department of Biomedical and Health Informatics (DBHi), Children's Hospital of Philadelphia, Philadelphia, PA 19104, USA
| | - Pasquale Striano
- Department of Neurosciences, Rehabilitation, Ophthalmology, Genetics, Maternal and Child Health, University of Genoa, Genoa, Italy; Pediatric Neurology and Muscular Diseases Unit, IRCCS Istituto Giannina Gaslini, Genoa, Italy
| | | | - Vincenzo Salpietro
- Department of Neurosciences, Rehabilitation, Ophthalmology, Genetics, Maternal and Child Health, University of Genoa, Genoa, Italy; Pediatric Neurology and Muscular Diseases Unit, IRCCS Istituto Giannina Gaslini, Genoa, Italy.
| | | | - Federico Zara
- Department of Neurosciences, Rehabilitation, Ophthalmology, Genetics, Maternal and Child Health, University of Genoa, Genoa, Italy; UOC Genetica Medica, IRCCS Giannina Gaslini, Genoa, Italy
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Han C, Alkhater R, Froukh T, Minassian AG, Galati M, Liu RH, Fotouhi M, Sommerfeld J, Alfrook AJ, Marshall C, Walker S, Bauer P, Scherer SW, Riess O, Buchert R, Minassian BA, McPherson PS. Epileptic Encephalopathy Caused by Mutations in the Guanine Nucleotide Exchange Factor DENND5A. Am J Hum Genet 2016; 99:1359-1367. [PMID: 27866705 DOI: 10.1016/j.ajhg.2016.10.006] [Citation(s) in RCA: 25] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/11/2016] [Accepted: 10/10/2016] [Indexed: 12/21/2022] Open
Abstract
Epileptic encephalopathies are a catastrophic group of epilepsies characterized by refractory seizures and cognitive arrest, often resulting from abnormal brain development. Here, we have identified an epileptic encephalopathy additionally featuring cerebral calcifications and coarse facial features caused by recessive loss-of-function mutations in DENND5A. DENND5A contains a DENN domain, an evolutionarily ancient enzymatic module conferring guanine nucleotide exchange factor (GEF) activity to multiple proteins serving as GEFs for Rabs, which are key regulators of membrane trafficking. DENND5A is detected predominantly in neuronal tissues, and its highest levels occur during development. Knockdown of DENND5A leads to striking alterations in neuronal development. Mechanistically, these changes appear to result from upregulation of neurotrophin receptors, leading to enhanced downstream signaling. Thus, we have identified a link between a DENN domain protein and neuronal development, dysfunction of which is responsible for a form of epileptic encephalopathy.
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Affiliation(s)
- Chanshuai Han
- Department of Neurology and Neurosurgery, Montreal Neurological Institute, McGill University, Montreal, QC H3A 2B4, Canada
| | - Reem Alkhater
- Johns Hopkins Aramco Healthcare, Dhahran 34465, Saudi Arabia
| | - Tawfiq Froukh
- Department of Biotechnology and Genetic Engineering, Faculty of Science, Philadelphia University, Amman 11118, Jordan
| | - Arakel G Minassian
- Centre for Applied Genomics, Genetics, and Genome Biology, Hospital for Sick Children, Toronto, ON M5G 0A4, Canada
| | - Melissa Galati
- Department of Neurology and Neurosurgery, Montreal Neurological Institute, McGill University, Montreal, QC H3A 2B4, Canada
| | - Rui Han Liu
- Department of Neurology and Neurosurgery, Montreal Neurological Institute, McGill University, Montreal, QC H3A 2B4, Canada
| | - Maryam Fotouhi
- Department of Neurology and Neurosurgery, Montreal Neurological Institute, McGill University, Montreal, QC H3A 2B4, Canada
| | - Julia Sommerfeld
- Institute of Medical Genetics and Applied Genomics, Rare Disease Center, University of Tübingen, Tübingen 72076, Germany
| | | | - Christian Marshall
- Centre for Applied Genomics, Genetics, and Genome Biology, Hospital for Sick Children, Toronto, ON M5G 0A4, Canada
| | - Susan Walker
- Centre for Applied Genomics, Genetics, and Genome Biology, Hospital for Sick Children, Toronto, ON M5G 0A4, Canada
| | - Peter Bauer
- Institute of Medical Genetics and Applied Genomics, Rare Disease Center, University of Tübingen, Tübingen 72076, Germany
| | - Stephen W Scherer
- Centre for Applied Genomics, Genetics, and Genome Biology, Hospital for Sick Children, Toronto, ON M5G 0A4, Canada; Department of Molecular Genetics and McLaughlin Centre, University of Toronto, Toronto, ON M5G 0A4, Canada
| | - Olaf Riess
- Institute of Medical Genetics and Applied Genomics, Rare Disease Center, University of Tübingen, Tübingen 72076, Germany
| | - Rebecca Buchert
- Institute of Medical Genetics and Applied Genomics, Rare Disease Center, University of Tübingen, Tübingen 72076, Germany
| | - Berge A Minassian
- Program in Genetics and Genome Biology, Department of Pediatrics (Neurology), Hospital for Sick Children and University of Toronto, Toronto, ON M5G 0A4, Canada
| | - Peter S McPherson
- Department of Neurology and Neurosurgery, Montreal Neurological Institute, McGill University, Montreal, QC H3A 2B4, Canada.
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