1
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Tello JA, Jiang L, Zohar Y, Restifo LL. Drosophila CASK regulates brain size and neuronal morphogenesis, providing a genetic model of postnatal microcephaly suitable for drug discovery. Neural Dev 2023; 18:6. [PMID: 37805506 PMCID: PMC10559581 DOI: 10.1186/s13064-023-00174-y] [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: 08/20/2023] [Accepted: 09/08/2023] [Indexed: 10/09/2023] Open
Abstract
BACKGROUND CASK-related neurodevelopmental disorders are untreatable. Affected children show variable severity, with microcephaly, intellectual disability (ID), and short stature as common features. X-linked human CASK shows dosage sensitivity with haploinsufficiency in females. CASK protein has multiple domains, binding partners, and proposed functions at synapses and in the nucleus. Human and Drosophila CASK show high amino-acid-sequence similarity in all functional domains. Flies homozygous for a hypomorphic CASK mutation (∆18) have motor and cognitive deficits. A Drosophila genetic model of CASK-related disorders could have great scientific and translational value. METHODS We assessed the effects of CASK loss of function on morphological phenotypes in Drosophila using established genetic, histological, and primary neuronal culture approaches. NeuronMetrics software was used to quantify neurite-arbor morphology. Standard nonparametric statistics methods were supplemented by linear mixed effects modeling in some cases. Microfluidic devices of varied dimensions were fabricated and numerous fluid-flow parameters were used to induce oscillatory stress fields on CNS tissue. Dissociation into viable neurons and neurite outgrowth in vitro were assessed. RESULTS We demonstrated that ∆18 homozygous flies have small brains, small heads, and short bodies. When neurons from developing CASK-mutant CNS were cultured in vitro, they grew small neurite arbors with a distinctive, quantifiable "bushy" morphology that was significantly rescued by transgenic CASK+. As in humans, the bushy phenotype showed dosage-sensitive severity. To overcome the limitations of manual tissue trituration for neuronal culture, we optimized the design and operation of a microfluidic system for standardized, automated dissociation of CNS tissue into individual viable neurons. Neurons from CASK-mutant CNS dissociated in the microfluidic system recapitulate the bushy morphology. Moreover, for any given genotype, device-dissociated neurons grew larger arbors than did manually dissociated neurons. This automated dissociation method is also effective for rodent CNS. CONCLUSIONS These biological and engineering advances set the stage for drug discovery using the Drosophila model of CASK-related disorders. The bushy phenotype provides a cell-based assay for compound screening. Nearly a dozen genes encoding CASK-binding proteins or transcriptional targets also have brain-development mutant phenotypes, including ID. Hence, drugs that improve CASK phenotypes might also benefit children with disorders due to mutant CASK partners.
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Affiliation(s)
- Judith A Tello
- Graduate Interdisciplinary Program in Neuroscience, University of Arizona, Tucson, AZ, 85721, USA
- Department of Neurology, University of Arizona Health Sciences, 1501 N. Campbell Ave, Tucson, AZ, 85724-5023, USA
- Present address: Department of Molecular Pathobiology, College of Dentistry, New York University, New York, NY, 10010, USA
| | - Linan Jiang
- Department of Aerospace and Mechanical Engineering, University of Arizona, Tucson, AZ, 85721, USA
| | - Yitshak Zohar
- Department of Aerospace and Mechanical Engineering, University of Arizona, Tucson, AZ, 85721, USA
- Department of Biomedical Engineering, University of Arizona, Tucson, AZ, 85721, USA
- BIO5 Interdisciplinary Research Institute, University of Arizona, Tucson, AZ, 85721, USA
| | - Linda L Restifo
- Graduate Interdisciplinary Program in Neuroscience, University of Arizona, Tucson, AZ, 85721, USA.
- Department of Neurology, University of Arizona Health Sciences, 1501 N. Campbell Ave, Tucson, AZ, 85724-5023, USA.
- BIO5 Interdisciplinary Research Institute, University of Arizona, Tucson, AZ, 85721, USA.
- Department of Cellular & Molecular Medicine, University of Arizona Health Sciences, Tucson, AZ, 85724, USA.
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2
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Mori T, Zhou M, Tabuchi K. Diverse Clinical Phenotypes of CASK-Related Disorders and Multiple Functional Domains of CASK Protein. Genes (Basel) 2023; 14:1656. [PMID: 37628707 PMCID: PMC10454856 DOI: 10.3390/genes14081656] [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: 08/07/2023] [Revised: 08/17/2023] [Accepted: 08/17/2023] [Indexed: 08/27/2023] Open
Abstract
CASK-related disorders are a form of rare X-linked neurological diseases and most of the patients are females. They are characterized by several symptoms, including microcephaly with pontine and cerebellar hypoplasia (MICPCH), epilepsy, congenital nystagmus, and neurodevelopmental disorders. Whole-genome sequencing has identified various mutations, including nonsense and missense mutations, from patients with CASK-related disorders, revealing correlations between specific mutations and clinical phenotypes. Notably, missense mutations associated with epilepsy and intellectual disability were found throughout the whole region of the CASK protein, while missense mutations related to microcephaly and MICPCH were restricted in certain domains. To investigate the pathophysiology of CASK-related disorders, research groups have employed diverse methods, including the generation of CASK knockout mice and the supplementation of CASK to rescue the phenotypes. These approaches have yielded valuable insights into the identification of functional domains of the CASK protein associated with a specific phenotype. Additionally, recent advancements in the AI-based prediction of protein structure, such as AlphaFold2, and the application of genome-editing techniques to generate CASK mutant mice carrying missense mutations from patients with CASK-related disorders, allow us to understand the pathophysiology of CASK-related disorders in more depth and to develop novel therapeutic methods for the fundamental treatment of CASK-related disorders.
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Affiliation(s)
- Takuma Mori
- Department of Neuroinnovation, Institute for Biomedical Sciences, Interdisciplinary Cluster for Cutting Edge Research, Shinshu University, Matsumoto 390-8621, Japan;
- Department of Molecular and Cellular Physiology, Shinshu University School of Medicine, Matsumoto 390-8621, Japan;
| | - Mengyun Zhou
- Department of Molecular and Cellular Physiology, Shinshu University School of Medicine, Matsumoto 390-8621, Japan;
| | - Katsuhiko Tabuchi
- Department of Neuroinnovation, Institute for Biomedical Sciences, Interdisciplinary Cluster for Cutting Edge Research, Shinshu University, Matsumoto 390-8621, Japan;
- Department of Molecular and Cellular Physiology, Shinshu University School of Medicine, Matsumoto 390-8621, Japan;
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3
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Guo Q, Kouyama-Suzuki E, Shirai Y, Cao X, Yanagawa T, Mori T, Tabuchi K. Structural Analysis Implicates CASK-Liprin-α2 Interaction in Cerebellar Granular Cell Death in MICPCH Syndrome. Cells 2023; 12:cells12081177. [PMID: 37190086 DOI: 10.3390/cells12081177] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/11/2022] [Revised: 04/06/2023] [Accepted: 04/10/2023] [Indexed: 05/17/2023] Open
Abstract
Microcephaly with pontine and cerebellar hypoplasia (MICPCH) syndrome is a neurodevelopmental disorder caused by the deficiency of the X-chromosomal gene CASK. However, the molecular mechanisms by which CASK deficiency causes cerebellar hypoplasia in this syndrome remain elusive. In this study, we used CASK knockout (KO) mice as models for MICPCH syndrome and investigated the effect of CASK mutants. Female CASK heterozygote KO mice replicate the progressive cerebellar hypoplasia observed in MICPCH syndrome. CASK KO cultured cerebellar granule (CG) cells show progressive cell death that can be rescued by co-infection with lentivirus expressing wild-type CASK. Rescue experiments with CASK deletion mutants identify that the CaMK, PDZ, and SH3, but not L27 and guanylate kinase domains of CASK are required for the survival of CG cells. We identify missense mutations in the CaMK domain of CASK derived from human patients that fail to rescue the cell death of cultured CASK KO CG cells. Machine learning-based structural analysis using AlphaFold 2.2 predicts that these mutations disrupt the structure of the binding interface with Liprin-α2. These results suggest that the interaction with Liprin-α2 via the CaMK domain of CASK may be involved in the pathophysiology of cerebellar hypoplasia in MICPCH syndrome.
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Affiliation(s)
- Qi Guo
- Department of Molecular and Cellular Physiology, Shinshu University School of Medicine, Matsumoto 390-8621, Japan
| | - Emi Kouyama-Suzuki
- Department of Molecular and Cellular Physiology, Shinshu University School of Medicine, Matsumoto 390-8621, Japan
| | - Yoshinori Shirai
- Department of Molecular and Cellular Physiology, Shinshu University School of Medicine, Matsumoto 390-8621, Japan
| | - Xueshan Cao
- College of Life Science and Oceanography, Shenzhen University, Shenzhen 518071, China
| | - Toru Yanagawa
- Department of Oral and Maxillofacial Surgery, Faculty of Medicine, University of Tsukuba, Tsukuba 305-8575, Japan
| | - Takuma Mori
- Department of Molecular and Cellular Physiology, Shinshu University School of Medicine, Matsumoto 390-8621, Japan
- Department of NeuroHealth Innovation, Institute for Biomedical Sciences, Interdisciplinary Cluster for Cutting Edge Research, Shinshu University, Matsumoto 390-8621, Japan
| | - Katsuhiko Tabuchi
- Department of Molecular and Cellular Physiology, Shinshu University School of Medicine, Matsumoto 390-8621, Japan
- Department of NeuroHealth Innovation, Institute for Biomedical Sciences, Interdisciplinary Cluster for Cutting Edge Research, Shinshu University, Matsumoto 390-8621, Japan
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4
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Gafner M, Boltshauser E, D'Abrusco F, Battini R, Romaniello R, D'Arrigo S, Zanni G, Leibovitz Z, Yosovich K, Lerman-Sagie T. Expanding the natural history of CASK-related disorders to the prenatal period. Dev Med Child Neurol 2023; 65:544-550. [PMID: 36175354 DOI: 10.1111/dmcn.15419] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/27/2022] [Revised: 08/24/2022] [Accepted: 08/24/2022] [Indexed: 11/30/2022]
Abstract
AIM To assess whether microcephaly with pontine and cerebellar hypoplasia (MICPCH) could manifest in the prenatal period in patients with calcium/calmodulin-dependent serine protein kinase (CASK) gene disorders. METHOD In this international multicentre retrospective study, we contacted a CASK parents' social media group and colleagues with expertise in cerebellar malformations and asked them to supply clinical and imaging information. Centiles and standard deviations (SD) were calculated according to age by nomograms. RESULTS The study consisted of 49 patients (44 females and 5 males). Information regarding prenatal head circumference was available in 19 patients; 11 out of 19 had a fetal head circumference below -2SD (range -4.1SD to -2.02SD, mean gestational age at diagnosis 20 weeks). Progressive prenatal deceleration of head circumference growth rate was observed in 15 out of 19. At birth, 20 out of 42 had a head circumference below -2SD. A total of 6 out of 15 fetuses had a TCD z-score below -2 (range -5.88 to -2.02). INTERPRETATION This study expands the natural history of CASK-related disorders to the prenatal period, showing evidence of progressive deceleration of head circumference growth rate, head circumference below -2SD, or small TCD. Most cases will not be diagnosed according to current recommendations for fetal central nervous system routine assessment. Consecutive measurements and genetic studies are advised in the presence of progressive deceleration of head circumference growth rates or small TCD. WHAT THIS PAPER ADDS Progressive deceleration of fetal head circumference growth rate can be observed. A small transcerebellar diameter is an additional important manifestation. Most cases will not be diagnosed according to current recommendations for fetal central nervous system routine assessment. Consecutive measurements are advised when measurements are within the low range of norm.
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Affiliation(s)
- Michal Gafner
- Department of Pediatrics B, Schneider Children's Medical Center of Israel, Petach Tikva, Israel
- Sackler Faculty of Medicine, Tel Aviv University, Tel Aviv, Israel
| | - Eugen Boltshauser
- Pediatric Neurology (Emeritus), Children's University Hospital, Zürich, Switzerland
| | - Fulvio D'Abrusco
- Department of Molecular Medicine, University of Pavia, Pavia, Italy
| | - Roberta Battini
- Department of Clinical and Experimental Medicine, University of Pisa, Pisa, Italy
- Department of Developmental Neuroscience, Istituto di Ricovero e Cura a Carattere Scientifico Fondazione Stella Maris, Pisa, Italy
| | - Romina Romaniello
- Neuropsychiatry and Neurorehabilitation Unit, Scientific Institute IRCCS, Italy
| | - Stefano D'Arrigo
- Department of Pediatric Neuroscience, Fondazione IRCCS Istituto Neurologico 'Carlo Besta', Milan, Italy
| | - Ginevra Zanni
- Unit of Muscular and Neurodegenerative Disorders Laboratory of Molecular Medicine, Department of Neurosciences, Bambino Gesù Children's Hospital, Rome, Italy
| | - Zvi Leibovitz
- Obstetrics and Gynaecology Ultrasound Unit, Bnai-Zion Medical Center, Haifa, Israel
- Rappaport Faculty of Medicine, Technion-Israel Institute of Technology, Haifa, Israel
- Fetal Neurology Clinic, Wolfson Medical Center, Holon, Israel
| | - Keren Yosovich
- Magen Center for Rare Diseases, Wolfson Medical Center, Holon, Israel
- Molecular Genetics Laboratory, Wolfson Medical Center, Holon, Israel
| | - Tally Lerman-Sagie
- Sackler Faculty of Medicine, Tel Aviv University, Tel Aviv, Israel
- Fetal Neurology Clinic, Wolfson Medical Center, Holon, Israel
- Magen Center for Rare Diseases, Wolfson Medical Center, Holon, Israel
- Pediatric Neurology Unit, Wolfson Medical Center, Holon, Israel
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5
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Dubbs H, Ortiz-Gonzalez X, Marsh ED. Pathogenic variants in CASK: Expanding the genotype-phenotype correlations. Am J Med Genet A 2022; 188:2617-2626. [PMID: 35670295 DOI: 10.1002/ajmg.a.62863] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/27/2021] [Revised: 05/04/2022] [Accepted: 05/16/2022] [Indexed: 01/24/2023]
Abstract
Pathogenic variants in CASK, an X-linked gene that plays a role in brain development and synaptic function, are the cause of both microcephaly with pontine and cerebellar hypoplasia (MICPCH), and X-linked intellectual disability (XLID) with or without nystagmus. MICPCH is caused by loss of function variants in CASK, typically affects females, and is associated with moderate-to-severe intellectual disability (ID). Additional findings, present in about one-third of individuals, include feeding difficulties, ophthalmologic issues, hypertonicity, epilepsy, and sensorineural hearing loss. Only a few affected males with MICPCH phenotype have been reported and most have had profound developmental disability and intractable epilepsy. The XLID phenotype is typically caused by missense variants and most often manifests in males; carrier females are mildly affected or unaffected. Nystagmus is often present. In total, over 175 patients have been reported in the literature. We now report an additional 11 patients with pathogenic variants in CASK that expand these phenotypes and reported genotype-phenotype correlations.
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Affiliation(s)
- Holly Dubbs
- Division of Neurology, Children's Hospital of Philadelphia, Philadelphia, Pennsylvania, USA
| | - Xilma Ortiz-Gonzalez
- Division of Neurology, Children's Hospital of Philadelphia, Philadelphia, Pennsylvania, USA.,Departments of Neurology and Pediatrics, Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania, USA
| | - Eric D Marsh
- Division of Neurology, Children's Hospital of Philadelphia, Philadelphia, Pennsylvania, USA.,Departments of Neurology and Pediatrics, Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania, USA
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6
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Wu S, Jiang C, Li J, Zhang G, Shen Y, Wang J. A novel missense variant in the CASK gene causes intellectual developmental disorder and microcephaly with pontine and cerebellar hypoplasia. BMC Med Genomics 2022; 15:127. [PMID: 35668446 PMCID: PMC9169347 DOI: 10.1186/s12920-022-01275-z] [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: 09/03/2021] [Accepted: 05/23/2022] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND Variants in the CASK gene result in a wide range of observed phenotypes in humans, such as FG Syndrome 4 and intellectual disabilities. Intellectual developmental disorder with microcephaly and pontine and cerebellar hypoplasia (MICPCH) is an X-linked disorder that affects females and is characterized by severely impaired intellectual development and variable degrees of pontocerebellar hypoplasia. Variants in CASK are the main genetic cause of MICPCH. Variants in CASK can explain most patients with MICPCH, but there are still some patients whose disease aetiology cannot be explained. CASE PRESENTATION An 11-month-old female diagnosed with MICPCH exhibited general developmental delays, microcephaly, and cerebellar hypoplasia. Whole-exome sequencing (WES) was used to find a novel heterozygous missense variant (NM_003688.3: c.638T>G) of CASK in this patient. Strikingly, this variant reduced the expression of CASK at the protein level but not at the mRNA level. By using protein structure prediction analysis, this study found that the amino acid change caused by the variant resulted in further changes in the stability of the protein structure, and these changes caused the downregulation of protein expression and loss of protein function. CONCLUSION In this study, we first reported a novel heterozygous pathogenic variant and a causative mechanism of MICPCH. The amino acid change cause by this variant led to changes in the protein structure and a decrease in its stability, which caused a loss of protein function. This study could be helpful to the genetic diagnosis of this disease.
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Affiliation(s)
- Sixian Wu
- Joint Laboratory of Reproductive Medicine, Gynaecology and Paediatric Diseases and Birth Defects of Ministry of Education, West China Second University Hospital, Sichuan University, Chengdu, 610041, People's Republic of China.,West China School of Pharmacy, Sichuan University, Chengdu, 610041, People's Republic of China
| | - Chuan Jiang
- Joint Laboratory of Reproductive Medicine, Gynaecology and Paediatric Diseases and Birth Defects of Ministry of Education, West China Second University Hospital, Sichuan University, Chengdu, 610041, People's Republic of China
| | - Jiaman Li
- West China School of Pharmacy, Sichuan University, Chengdu, 610041, People's Republic of China
| | - Guohui Zhang
- Joint Laboratory of Reproductive Medicine, Gynaecology and Paediatric Diseases and Birth Defects of Ministry of Education, West China Second University Hospital, Sichuan University, Chengdu, 610041, People's Republic of China
| | - Ying Shen
- Joint Laboratory of Reproductive Medicine, Gynaecology and Paediatric Diseases and Birth Defects of Ministry of Education, West China Second University Hospital, Sichuan University, Chengdu, 610041, People's Republic of China.
| | - Jing Wang
- Department of Obstetrics and Gynaecology, West China Second University Hospital of Sichuan University and Key Laboratory of Birth Defects and Related Diseases of Women and Children, Sichuan University, Ministry of Education, Chengdu, 610041, People's Republic of China.
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7
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Zhang Y, Nie Y, Mu Y, Zheng J, Xu X, Zhang F, Shu J, Liu Y. A de novo variant in CASK gene causing intellectual disability and brain hypoplasia: a case report and literature review. Ital J Pediatr 2022; 48:73. [PMID: 35550617 PMCID: PMC9097383 DOI: 10.1186/s13052-022-01248-z] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/10/2021] [Accepted: 03/17/2022] [Indexed: 12/02/2022] Open
Abstract
Background The pathogenic variation of CASK gene can cause CASK related mental disorders. The main clinical manifestations are microcephaly with pontine and cerebellar hypoplasia, X-linked mental disorders with or without nystagmus and FG syndrome. The main pathogenic mechanism is the loss of function of related protein caused by variant. We reported a Chinese male newborn with a de novo variant in CASK gene. Case presentation We present an 18-day-old baby with growth retardation and brain hypoplasia. Whole-exome sequencing was performed, which detected a hemizygous missense variant c.764G > A of CASK gene. The variant changed the 255th amino acid from Arg to His. Software based bioinformatics analyses were conducted to infer its functional effect. Conclusions In this paper, a de novo variant of CASK gene was reported. Moreover, a detailed description of all the cases described in the literature is reported. CASK variants cause a variety of clinical phenotypes. Its diagnosis is difficult due to the lack of typical clinical symptoms. Genetic testing should be performed as early as possible if this disease is suspected. This case provides an important reference for the diagnosis and treatment of future cases.
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Affiliation(s)
- Ying Zhang
- Department of Neonatology, Tianjin Children's Hospital (Tianjin University Children's Hospital), No. 238 Longyan Road, Beichen District, Tianjin, 300134, China.,Graduate College of Tianjin Medical University, Tianjin, China
| | - Yanyan Nie
- Department of Neonatology, Tianjin Children's Hospital (Tianjin University Children's Hospital), No. 238 Longyan Road, Beichen District, Tianjin, 300134, China
| | - Yu Mu
- Department of Neonatology, Tianjin Children's Hospital (Tianjin University Children's Hospital), No. 238 Longyan Road, Beichen District, Tianjin, 300134, China
| | - Jie Zheng
- Graduate College of Tianjin Medical University, Tianjin, China
| | - Xiaowei Xu
- Tianjin Key Laboratory of Birth Defects for Prevention and Treatment, Tianjin, China.,Tianjin Pediatric Research Institute, Tianjin Children's Hospital (Tianjin University Children's Hospital), No. 238 Longyan Road, Beichen District, Tianjin, 300134, China
| | - Fang Zhang
- Department of Neonatology, Tianjin Children's Hospital (Tianjin University Children's Hospital), No. 238 Longyan Road, Beichen District, Tianjin, 300134, China
| | - Jianbo Shu
- Tianjin Key Laboratory of Birth Defects for Prevention and Treatment, Tianjin, China. .,Tianjin Pediatric Research Institute, Tianjin Children's Hospital (Tianjin University Children's Hospital), No. 238 Longyan Road, Beichen District, Tianjin, 300134, China.
| | - Yang Liu
- Department of Neonatology, Tianjin Children's Hospital (Tianjin University Children's Hospital), No. 238 Longyan Road, Beichen District, Tianjin, 300134, China.
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8
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Mukherjee K, LaConte LEW, Srivastava S. The Non-Linear Path from Gene Dysfunction to Genetic Disease: Lessons from the MICPCH Mouse Model. Cells 2022; 11:1131. [PMID: 35406695 PMCID: PMC8997851 DOI: 10.3390/cells11071131] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/27/2022] [Revised: 03/09/2022] [Accepted: 03/24/2022] [Indexed: 11/17/2022] Open
Abstract
Most human disease manifests as a result of tissue pathology, due to an underlying disease process (pathogenesis), rather than the acute loss of specific molecular function(s). Successful therapeutic strategies thus may either target the correction of a specific molecular function or halt the disease process. For the vast majority of brain diseases, clear etiologic and pathogenic mechanisms are still elusive, impeding the discovery or design of effective disease-modifying drugs. The development of valid animal models and their proper characterization is thus critical for uncovering the molecular basis of the underlying pathobiological processes of brain disorders. MICPCH (microcephaly and pontocerebellar hypoplasia) is a monogenic condition that results from variants of an X-linked gene, CASK (calcium/calmodulin-dependent serine protein kinase). CASK variants are associated with a wide range of clinical presentations, from lethality and epileptic encephalopathies to intellectual disabilities, microcephaly, and autistic traits. We have examined CASK loss-of-function mutations in model organisms to simultaneously understand the pathogenesis of MICPCH and the molecular function/s of CASK. Our studies point to a highly complex relationship between the potential molecular function/s of CASK and the phenotypes observed in model organisms and humans. Here we discuss the implications of our observations from the pathogenesis of MICPCH as a cautionary narrative against oversimplifying molecular interpretations of data obtained from genetically modified animal models of human diseases.
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Affiliation(s)
- Konark Mukherjee
- Fralin Biomedical Research Institute at VTC, Roanoke, VA 24016, USA; (L.E.W.L.); (S.S.)
- Department of Psychiatry, Virginia Tech Carilion School of Medicine, Roanoke, VA 24016, USA
| | - Leslie E. W. LaConte
- Fralin Biomedical Research Institute at VTC, Roanoke, VA 24016, USA; (L.E.W.L.); (S.S.)
- Department of Basic Science Education, Virginia Tech Carilion School of Medicine, Roanoke, VA 24016, USA
| | - Sarika Srivastava
- Fralin Biomedical Research Institute at VTC, Roanoke, VA 24016, USA; (L.E.W.L.); (S.S.)
- Department of Internal Medicine, Virginia Tech Carilion School of Medicine, Roanoke, VA 24016, USA
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9
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Russ N, Schröder M, Berger BT, Mandel S, Aydogan Y, Mauer S, Pohl C, Drewry DH, Chaikuad A, Müller S, Knapp S. Design and Development of a Chemical Probe for Pseudokinase Ca 2+/calmodulin-Dependent Ser/Thr Kinase. J Med Chem 2021; 64:14358-14376. [PMID: 34543009 DOI: 10.1021/acs.jmedchem.1c00845] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
CASK (Ca2+/calmodulin-dependent Ser/Thr kinase) is a member of the MAGUK (membrane-associated guanylate kinase) family that functions as neurexin kinases with roles implicated in neuronal synapses and trafficking. The lack of a canonical DFG motif, which is altered to GFG in CASK, led to the classification as a pseudokinase. However, functional studies revealed that CASK can still phosphorylate substrates in the absence of divalent metals. CASK dysfunction has been linked to many diseases, including colorectal cancer, Parkinson's disease, and X-linked mental retardation, suggesting CASK as a potential drug target. Here, we exploited structure-based design for the development of highly potent and selective CASK inhibitors based on 2,4-diaminopyrimidine-5-carboxamides targeting an unusual pocket created by the GFG motif. The presented inhibitor design offers a more general strategy for the development of pseudokinase ligands that harbor unusual sequence motifs. It also provides a first chemical probe for studying the biological roles of CASK.
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Affiliation(s)
- Nadine Russ
- Structural Genomics Consortium (SGC), Buchmann Institute for Life Sciences (BMLS), Goethe University Frankfurt am Main, Max-von-Laue-Str. 15, Frankfurt am Main 60438, Germany.,Institut für Pharmazeutische Chemie, Goethe University Frankfurt am Main, Max-von-Laue-Str. 9, Frankfurt am Main 60438, Germany
| | - Martin Schröder
- Structural Genomics Consortium (SGC), Buchmann Institute for Life Sciences (BMLS), Goethe University Frankfurt am Main, Max-von-Laue-Str. 15, Frankfurt am Main 60438, Germany.,Institut für Pharmazeutische Chemie, Goethe University Frankfurt am Main, Max-von-Laue-Str. 9, Frankfurt am Main 60438, Germany
| | - Benedict-Tilman Berger
- Structural Genomics Consortium (SGC), Buchmann Institute for Life Sciences (BMLS), Goethe University Frankfurt am Main, Max-von-Laue-Str. 15, Frankfurt am Main 60438, Germany.,Institut für Pharmazeutische Chemie, Goethe University Frankfurt am Main, Max-von-Laue-Str. 9, Frankfurt am Main 60438, Germany
| | - Sebastian Mandel
- Structural Genomics Consortium (SGC), Buchmann Institute for Life Sciences (BMLS), Goethe University Frankfurt am Main, Max-von-Laue-Str. 15, Frankfurt am Main 60438, Germany.,Institut für Pharmazeutische Chemie, Goethe University Frankfurt am Main, Max-von-Laue-Str. 9, Frankfurt am Main 60438, Germany
| | - Yagmur Aydogan
- Structural Genomics Consortium (SGC), Buchmann Institute for Life Sciences (BMLS), Goethe University Frankfurt am Main, Max-von-Laue-Str. 15, Frankfurt am Main 60438, Germany.,Institut für Pharmazeutische Chemie, Goethe University Frankfurt am Main, Max-von-Laue-Str. 9, Frankfurt am Main 60438, Germany
| | - Sandy Mauer
- Buchman Institute for Molecular Life Science and Institute of Biochemistry II, Goethe University Frankfurt am Main, Max-von-Laue-Str. 15, Frankfurt am Main 60438, Germany
| | - Christian Pohl
- Buchman Institute for Molecular Life Science and Institute of Biochemistry II, Goethe University Frankfurt am Main, Max-von-Laue-Str. 15, Frankfurt am Main 60438, Germany
| | - David H Drewry
- Structural Genomics Consortium, UNC Eshelman School of Pharmacy, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599, United States.,UNC Lineberger Comprehensive Cancer Center, UNC Eshelman School of Pharmacy, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599, United States
| | - Apirat Chaikuad
- Structural Genomics Consortium (SGC), Buchmann Institute for Life Sciences (BMLS), Goethe University Frankfurt am Main, Max-von-Laue-Str. 15, Frankfurt am Main 60438, Germany.,Institut für Pharmazeutische Chemie, Goethe University Frankfurt am Main, Max-von-Laue-Str. 9, Frankfurt am Main 60438, Germany
| | - Susanne Müller
- Structural Genomics Consortium (SGC), Buchmann Institute for Life Sciences (BMLS), Goethe University Frankfurt am Main, Max-von-Laue-Str. 15, Frankfurt am Main 60438, Germany.,Institut für Pharmazeutische Chemie, Goethe University Frankfurt am Main, Max-von-Laue-Str. 9, Frankfurt am Main 60438, Germany
| | - Stefan Knapp
- Structural Genomics Consortium (SGC), Buchmann Institute for Life Sciences (BMLS), Goethe University Frankfurt am Main, Max-von-Laue-Str. 15, Frankfurt am Main 60438, Germany.,Institut für Pharmazeutische Chemie, Goethe University Frankfurt am Main, Max-von-Laue-Str. 9, Frankfurt am Main 60438, Germany.,German Cancer Network (DKTK) and Frankfurt Cancer Institute (FCI), Goethe University Frankfurt am Main, Frankfurt am Main 60438, Germany
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10
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Nuovo S, Micalizzi A, Romaniello R, Arrigoni F, Ginevrino M, Casella A, Serpieri V, D'Arrigo S, Briguglio M, Salerno GG, Rossato S, Sartori S, Leuzzi V, Battini R, Ben-Zeev B, Graziano C, Mirabelli Badenier M, Brankovic V, Nardocci N, Spiegel R, Petković Ramadža D, Vento G, Marti I, Simonati A, Dipresa S, Freri E, Mazza T, Bassi MT, Bosco L, Travaglini L, Zanni G, Bertini ES, Vanacore N, Borgatti R, Valente EM. Refining the mutational spectrum and gene-phenotype correlates in pontocerebellar hypoplasia: results of a multicentric study. J Med Genet 2021; 59:399-409. [PMID: 34085948 DOI: 10.1136/jmedgenet-2020-107497] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/05/2020] [Revised: 01/27/2021] [Accepted: 02/09/2021] [Indexed: 12/26/2022]
Abstract
BACKGROUND Pontocerebellar hypoplasias (PCH) comprise a group of genetically heterogeneous disorders characterised by concurrent hypoplasia of the pons and the cerebellum and variable clinical and imaging features. The current classification includes 13 subtypes, with ~20 known causative genes. Attempts have been made to delineate the phenotypic spectrum associated to specific PCH genes, yet clinical and neuroradiological features are not consistent across studies, making it difficult to define gene-specific outcomes. METHODS We performed deep clinical and imaging phenotyping in 56 probands with a neuroradiological diagnosis of PCH, who underwent NGS-based panel sequencing of PCH genes and MLPA for CASK rearrangements. Next, we conducted a phenotype-based unsupervised hierarchical cluster analysis to investigate associations between genes and specific phenotypic clusters. RESULTS A genetic diagnosis was obtained in 43 probands (77%). The most common causative gene was CASK, which accounted for nearly half cases (45%) and was mutated in females and occasionally in males. The European founder mutation p.Ala307Ser in TSEN54 and pathogenic variants in EXOSC3 accounted for 18% and 9% of cases, respectively. VLDLR, TOE1 and RARS2 were mutated in single patients. We were able to confirm only few previously reported associations, including jitteriness and clonus with TSEN54 and lower motor neuron signs with EXOSC3. When considering multiple features simultaneously, a clear association with a phenotypic cluster only emerged for EXOSC3. CONCLUSION CASK represents the major PCH causative gene in Italy. Phenotypic variability associated with the most common genetic causes of PCH is wider than previously thought, with marked overlap between CASK and TSEN54-associated disorders.
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Affiliation(s)
- Sara Nuovo
- Department of Human Neuroscience, Sapienza University of Rome, Roma, Italy
| | - Alessia Micalizzi
- Laboratory of Medical Genetics, IRCCS Bambino Gesù Children's Hospital, Roma, Italy
| | - Romina Romaniello
- Neuropsychiatry and Neurorehabilitation Unit, Scientific Institute IRCCS Eugenio Medea, Bosisio Parini, Lecco, Italy
| | - Filippo Arrigoni
- Neuroimaging Lab, Scientific Institute IRCCS Eugenio Medea, Bosisio Parini, Lecco, Italy
| | - Monia Ginevrino
- Laboratory of Medical Genetics, IRCCS Bambino Gesù Children's Hospital, Roma, Italy.,Istituto di Medicina Genomica, Università Cattolica del Sacro Cuore, Fondazione Policlinico Universitario "A. Gemelli" IRCCS, Roma, Italy
| | - Antonella Casella
- IRCCS Mondino Foundation, Pavia, Italy.,Department of Molecular Medicine, University of Pavia, Pavia, Italy
| | | | - Stefano D'Arrigo
- Department of Developmental Neurology, Fondazione IRCCS, Istituto Neurologico Carlo Besta, Milano, Italy
| | - Marilena Briguglio
- Interdepartmental Program "Autism 0-90", "G. Martino" University Hospital of Messina, Messina, Italy
| | - Grazia Gabriella Salerno
- Child Neurology Unit, Department of Paediatrics, Azienda USL-IRCCS di Reggio Emilia, Reggio Emilia, Italy
| | - Sara Rossato
- U.O.C. Pediatria, Ospedale San Bortolo, Vicenza, Italy
| | - Stefano Sartori
- Paediatric Neurology and Neurophysiology Unit, Department of Women's and Children's Health, University Hospital of Padova, Padova, Italy
| | - Vincenzo Leuzzi
- Department of Human Neuroscience, Sapienza University of Rome, Roma, Italy
| | - Roberta Battini
- Department of Clinical and Experimental Medicine, University of Pisa, Pisa, Italy.,Department of Developmental Neuroscience, IRCCS Stella Maris Foundation, Pisa, Italy
| | - Bruria Ben-Zeev
- Pediatric Neurology Department, The Edmond and Lilly Safra Pediatric Hospital, Sheba Medical Center, Tel Hashomer, Israel.,Sackler School of Medicine, Tel Aviv University, Tel Aviv, Israel
| | - Claudio Graziano
- Medical Genetics Unit, AOU Policlinico di S. Orsola, Bologna, Italy
| | - Marisol Mirabelli Badenier
- Fondazione Istituto David Chiossone Onlus, Genova, Italy.,Child Neuropsychiatry Unit, Department of Neurosciences and Rehabilitation, Istituto G. Gaslini, Genova, Italy
| | - Vesna Brankovic
- Clinic for Child Neurology and Psychiatry, University of Belgrade, Belgrade, Serbia
| | - Nardo Nardocci
- Department of Child Neurology, Fondazione IRCCS Istituto Neurologico Carlo Besta, Milano, Italy
| | - Ronen Spiegel
- Department of Pediatrics B, Emek Medical Center, Afula, Israel.,Rappaport School of Medicine, Technion, Haifa, Israel
| | | | - Giovanni Vento
- Division of Neonatology, Department of Woman and Child Health and Public Health, Child Health Area, Fondazione Policlinico Universitario A. Gemelli IRCCS-Università Cattolica del Sacro Cuore, Roma, Italy
| | - Itxaso Marti
- Pediatric Neurology, Hospital Universitario Donostia, Biodonostia, Universidad del País Vasco UPV-EHU, San Sebastian, Spain
| | - Alessandro Simonati
- Department of Surgery, Dentistry, Paediatrics and Gynaecology, University of Verona School of Medicine and Department of Clinical Neuroscience AOUI Verona, Verona, Italy
| | - Savina Dipresa
- Department of Medicine, Unit of Andrology and Reproductive Medicine, University of Padova, Padova, Italy
| | - Elena Freri
- Department of Child Neurology, Fondazione IRCCS Istituto Neurologico Carlo Besta, Milano, Italy
| | - Tommaso Mazza
- Bioinformatics Unit, IRCCS Casa Sollievo della Sofferenza, S. Giovanni Rotondo, Italy
| | - Maria Teresa Bassi
- Laboratory of Molecular Biology, Scientific Institute IRCCS Eugenio Medea, Bosisio Parini, Lecco, Italy
| | - Luca Bosco
- Unit of Neuromuscular and Neurodegenerative Diseases, Department of Neuroscience and Neurorehabilitation, IRCCS Bambino Gesù Children's Hospital, Roma, Italy
| | - Lorena Travaglini
- Unit of Neuromuscular and Neurodegenerative Diseases, Department of Neuroscience and Neurorehabilitation, IRCCS Bambino Gesù Children's Hospital, Roma, Italy
| | - Ginevra Zanni
- Unit of Neuromuscular and Neurodegenerative Diseases, Department of Neuroscience and Neurorehabilitation, IRCCS Bambino Gesù Children's Hospital, Roma, Italy
| | - Enrico Silvio Bertini
- Unit of Neuromuscular and Neurodegenerative Diseases, Department of Neuroscience and Neurorehabilitation, IRCCS Bambino Gesù Children's Hospital, Roma, Italy
| | - Nicola Vanacore
- National Center for Disease Prevention and Health Promotion, Italian National Institute of Health, Roma, Italy
| | - Renato Borgatti
- Child Neurology and Psychiatry Unit, IRCCS Mondino Foundation, Pavia, Italy.,Department of Brain and Behavioral Sciences, University of Pavia, Pavia, Italy
| | - Enza Maria Valente
- IRCCS Mondino Foundation, Pavia, Italy .,Department of Molecular Medicine, University of Pavia, Pavia, Italy
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11
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Nishio Y, Kidokoro H, Takeo T, Narita H, Sawamura F, Narita K, Kawano Y, Nakata T, Muramatsu H, Hara S, Kaname T, Natsume J. The eldest case of MICPCH with CASK mutation exhibiting gross motor regression. Brain Dev 2021; 43:459-463. [PMID: 33272775 DOI: 10.1016/j.braindev.2020.11.007] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/26/2020] [Revised: 11/02/2020] [Accepted: 11/15/2020] [Indexed: 11/28/2022]
Abstract
BACKGROUND MICPCH is manifested as microcephaly associated with pontocerebellar hypoplasia and global developmental delay but developmental regression has never been reported. We describe the detailed clinical history of a woman with intellectual disability and microcephaly with pontine and cerebellar hypoplasia (MICPCH) with a CASK mutation who exhibited gross motor regression after adolescence. CASE The patient experienced severe motor and intellectual developmental delay with microcephaly from infancy. The initial diagnosis was Rett syndrome based on her clinical features, including hand stereotypes and the absence of structural abnormality on magnetic resonance imaging (MRI) performed at the age of 5 years. Although gross motor abilities developed slowly and she could walk independently, she never acquired speech or understanding of languages. After adolescence, her motor ability gradually regressed so that she was unable to stand without support and moved with a wheelchair. At the age of 31 years, because of her atypical clinical course for Rett syndrome, whole exome sequencing was performed, which revealed a de novo heterozygous c.2068 + 1G > A mutation in the CASK gene (NM_001126055). Brain MRI revealed mild pontocerebellar hypoplasia compatible with the clinical phenotype of MICPCH. DISCUSSION This case suggests that MICPCH with a CASK mutation might cause developmental regression after adolescence and might be regarded as a neurodegenerative disorder.
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Affiliation(s)
- Yosuke Nishio
- Department of Pediatrics, Nagoya University Graduate School of Medicine, Nagoya, Japan; Department of Pediatrics, TOYOTA Memorial Hospital, Toyota, Japan
| | - Hiroyuki Kidokoro
- Department of Pediatrics, Nagoya University Graduate School of Medicine, Nagoya, Japan.
| | - Toshiki Takeo
- Department of Pediatrics, TOYOTA Memorial Hospital, Toyota, Japan
| | - Hajime Narita
- Department of Pediatrics, TOYOTA Memorial Hospital, Toyota, Japan
| | - Fumi Sawamura
- Department of Pediatrics, Nagoya University Graduate School of Medicine, Nagoya, Japan
| | - Kotaro Narita
- Department of Pediatrics, Nagoya University Graduate School of Medicine, Nagoya, Japan
| | - Yoshihiko Kawano
- Department of Pediatrics, TOYOTA Memorial Hospital, Toyota, Japan
| | - Tomohiko Nakata
- Department of Pediatrics, Nagoya University Graduate School of Medicine, Nagoya, Japan
| | - Hideki Muramatsu
- Department of Pediatrics, Nagoya University Graduate School of Medicine, Nagoya, Japan
| | - Shinya Hara
- Department of Pediatrics, TOYOTA Memorial Hospital, Toyota, Japan
| | - Tadashi Kaname
- Department of Genome Medicine, National Center for Child Health and Development, Tokyo, Japan
| | - Jun Natsume
- Department of Pediatrics, Nagoya University Graduate School of Medicine, Nagoya, Japan; Department of Disability Medicine, Nagoya University Graduate School of Medicine, Nagoya, Japan
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12
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Lee J, Park JE, Lee C, Kim AR, Kim BJ, Park WY, Ki CS, Lee J. Genomic Analysis of Korean Patient With Microcephaly. Front Genet 2021; 11:543528. [PMID: 33584783 PMCID: PMC7876370 DOI: 10.3389/fgene.2020.543528] [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: 03/17/2020] [Accepted: 12/30/2020] [Indexed: 12/17/2022] Open
Abstract
Microcephaly is a prevalent phenotype in patients with neurodevelopmental problems, often with genetic causes. We comprehensively investigated the clinical phenotypes and genetic background of microcephaly in 40 Korean patients. We analyzed their clinical phenotypes and radiologic images and conducted whole exome sequencing (WES) and analysis of copy number variation (CNV). Infantile hypotonia and developmental delay were present in all patients. Thirty-four patients (85%) showed primary microcephaly. The diagnostic yield from the WES and CNV analyses was 47.5%. With WES, we detected pathogenic or likely pathogenic variants that were previously associated with microcephaly in 12 patients (30%); nine of these were de novo variants with autosomal dominant inheritance. Two unrelated patients had mutations in the KMT2A gene. In 10 other patients, we found mutations in the GNB1, GNAO1, TCF4, ASXL1, SMC1A, VPS13B, ACTG1, EP300, and KMT2D genes. Seven patients (17.5%) were diagnosed with pathogenic CNVs. Korean patients with microcephaly show a genetic spectrum that is different from that of patients with microcephaly of other ethnicities. WES along with CNV analysis represents an effective approach for diagnosis of the underlying causes of microcephaly.
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Affiliation(s)
- Jiwon Lee
- Department of Pediatrics, Samsung Medical Center, Sungkyunkwan University School of Medicine, Seoul, South Korea
| | - Jong Eun Park
- Department of Laboratory Medicine and Genetics, Hanyang University Guri Hospital, Hanyang University College of Medicine, Guri, South Korea
| | - Chung Lee
- Samsung Genome Institute, Sungkyunkwan University School of Medicine, Seoul, South Korea
| | - Ah Reum Kim
- Samsung Genome Institute, Sungkyunkwan University School of Medicine, Seoul, South Korea
| | - Byung Joon Kim
- Department of Neurology, Samsung Medical Center, Sungkyunkwan University School of Medicine, Seoul, South Korea
| | - Woong-Yang Park
- Samsung Genome Institute, Sungkyunkwan University School of Medicine, Seoul, South Korea
| | | | - Jeehun Lee
- Department of Pediatrics, Samsung Medical Center, Sungkyunkwan University School of Medicine, Seoul, South Korea
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13
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Andrew DR, Moe ME, Chen D, Tello JA, Doser RL, Conner WE, Ghuman JK, Restifo LL. Spontaneous motor-behavior abnormalities in two Drosophila models of neurodevelopmental disorders. J Neurogenet 2020; 35:1-22. [PMID: 33164597 DOI: 10.1080/01677063.2020.1833005] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
Abstract
Mutations in hundreds of genes cause neurodevelopmental disorders with abnormal motor behavior alongside cognitive deficits. Boys with fragile X syndrome (FXS), a leading monogenic cause of intellectual disability, often display repetitive behaviors, a core feature of autism. By direct observation and manual analysis, we characterized spontaneous-motor-behavior phenotypes of Drosophila dfmr1 mutants, an established model for FXS. We recorded individual 1-day-old adult flies, with mature nervous systems and prior to the onset of aging, in small arenas. We scored behavior using open-source video-annotation software to generate continuous activity timelines, which were represented graphically and quantitatively. Young dfmr1 mutants spent excessive time grooming, with increased bout number and duration; both were rescued by transgenic wild-type dfmr1+. By two grooming-pattern measures, dfmr1-mutant flies showed elevated repetitions consistent with perseveration, which is common in FXS. In addition, the mutant flies display a preference for grooming posterior body structures, and an increased rate of grooming transitions from one site to another. We raise the possibility that courtship and circadian rhythm defects, previously reported for dfmr1 mutants, are complicated by excessive grooming. We also observed significantly increased grooming in CASK mutants, despite their dramatically decreased walking phenotype. The mutant flies, a model for human CASK-related neurodevelopmental disorders, displayed consistently elevated grooming indices throughout the assay, but transient locomotory activation immediately after placement in the arena. Based on published data identifying FMRP-target transcripts and functional analyses of mutations causing human genetic neurodevelopmental disorders, we propose the following proteins as candidate mediators of excessive repetitive behaviors in FXS: CaMKIIα, NMDA receptor subunits 2A and 2B, NLGN3, and SHANK3. Together, these fly-mutant phenotypes and mechanistic insights provide starting points for drug discovery to identify compounds that reduce dysfunctional repetitive behaviors.
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Affiliation(s)
- David R Andrew
- Department of Neurology, University of Arizona Health Sciences, Tucson, AZ, USA.,Center for Insect Science, University of Arizona, Tucson, AZ, USA.,Department of Biological Sciences, Lycoming College, Williamsport, PA, USA
| | - Mariah E Moe
- Department of Neurology, University of Arizona Health Sciences, Tucson, AZ, USA
| | - Dailu Chen
- Department of Neurology, University of Arizona Health Sciences, Tucson, AZ, USA
| | - Judith A Tello
- Department of Neurology, University of Arizona Health Sciences, Tucson, AZ, USA.,Graduate Interdisciplinary Program in Neuroscience, University of Arizona, Tucson, AZ, USA
| | - Rachel L Doser
- Department of Neurology, University of Arizona Health Sciences, Tucson, AZ, USA
| | - William E Conner
- Department of Biology, Wake Forest University, Winston-Salem, NC, USA
| | - Jaswinder K Ghuman
- Department of Psychiatry, University of Arizona Health Sciences, Tucson, AZ, USA
| | - Linda L Restifo
- Department of Neurology, University of Arizona Health Sciences, Tucson, AZ, USA.,Center for Insect Science, University of Arizona, Tucson, AZ, USA.,Graduate Interdisciplinary Program in Neuroscience, University of Arizona, Tucson, AZ, USA.,BIO5 Interdisciplinary Research Institute, University of Arizona, Tucson, AZ, USA
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14
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LaConte LEW, Chavan V, DeLuca S, Rubin K, Malc J, Berry S, Gail Summers C, Mukherjee K. An N-terminal heterozygous missense CASK mutation is associated with microcephaly and bilateral retinal dystrophy plus optic nerve atrophy. Am J Med Genet A 2018; 179:94-103. [PMID: 30549415 DOI: 10.1002/ajmg.a.60687] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/09/2018] [Revised: 09/26/2018] [Accepted: 10/17/2018] [Indexed: 11/08/2022]
Abstract
Heterozygous loss-of-function mutations in the X-linked gene CASK are associated with mental retardation and microcephaly with pontine and cerebellar hypoplasia (MICPCH) and ophthalmological disorders including optic nerve atrophy (ONA) and optic nerve hypoplasia (ONH). Recently, we have demonstrated that CASK(+/-) mice display ONH with 100% penetrance but exhibit no change in retinal lamination or structure. It is not clear if CASK loss-of-function predominantly affects retinal ganglion cells, or if other retinal cells like photoreceptors are also involved. Here, we report a heterozygous missense mutation in the N-terminal calcium/calmodulin-dependent kinase (CaMK) domain of the CASK protein in which a highly conserved leucine is mutated to the cyclic amino acid proline. In silico analysis suggests that the mutation may produce destabilizing structural changes. Experimentally, we observe pronounced misfolding and insolubility of the CASKL209P protein. Interestingly, the remaining soluble mutant protein fails to interact with Mint1, which specifically binds to CASK's CaMK domain, suggesting a mechanism for the phenotypes observed with the CASKL209P mutation. In addition to microcephaly, cerebellar hypoplasia and delayed development, the subject with the L209P mutation also presented with bilateral retinal dystrophy and ONA. Electroretinography indicated that rod photoreceptors are the most prominently affected cells. Our data suggest that the CASK interactions mediated by the CaMK domain may play a crucial role in retinal function, and thus, in addition to ONH, individuals with mutations in the CASK gene may exhibit other retinal disorders, depending on the nature of mutation.
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Affiliation(s)
| | - Vrushali Chavan
- Virginia Tech Carilion Research Institute, Roanoke, Virginia
| | | | - Karol Rubin
- Department of Genetics, Cell Biology & Development, University of Minnesota, Minneapolis, Minnesota
| | - Jessica Malc
- Virginia Tech Carilion Research Institute, Roanoke, Virginia
| | - Susan Berry
- Department of Pediatrics, University of Minnesota, Minneapolis, Minnesota.,Department of Genetics, Cell Biology & Development, University of Minnesota, Minneapolis, Minnesota
| | - C Gail Summers
- Department of Pediatrics, University of Minnesota, Minneapolis, Minnesota.,Department of Ophthalmology & Visual Neurosciences, University of Minnesota, Minneapolis, Minnesota
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