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Scott EY, Woolard KD, Finno CJ, Murray JD. Cerebellar Abiotrophy Across Domestic Species. THE CEREBELLUM 2019; 17:372-379. [PMID: 29294214 DOI: 10.1007/s12311-017-0914-1] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/24/2023]
Abstract
Cerebellar abiotrophy (CA) is a neurodegenerative disorder affecting the cerebellum and occurs in multiple species. Although CA is well researched in humans and mice, domestic species such as the dog, cat, sheep, cow, and horse receive little recognition. This may be due to few studies addressing the mechanism of CA in these species. However, valuable information can still be extracted from these cases. A review of the clinicohistologic phenotype of CA in these species and determining the various etiologies of CA may aid in determining conserved and required pathways necessary for proper cerebellar development and function. This review outlines research approaches of studies of CA in domestic species, compared to the approaches used in mice, with the objective of comparing CA in domestic species while identifying areas for further research efforts.
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Affiliation(s)
- Erica Yuki Scott
- Department of Animal Science, University of California, Davis, Meyer Hall, 1 Shields Ave, Davis, CA, 95616, USA
| | - Kevin Douglas Woolard
- Department of Pathology, Microbiology & Immunology, University of California, Davis, Davis, CA, USA
| | - Carrie J Finno
- Department of Population Health and Reproduction, University of California, Davis, Davis, CA, USA
| | - James D Murray
- Department of Animal Science, University of California, Davis, Meyer Hall, 1 Shields Ave, Davis, CA, 95616, USA.
- Department of Population Health and Reproduction, University of California, Davis, Davis, CA, USA.
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52
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DeSmidt AA, Zou B, Grati M, Yan D, Mittal R, Yao Q, Richmond MT, Denyer S, Liu XZ, Lu Z. Zebrafish Model for Nonsyndromic X-Linked Sensorineural Deafness, DFNX1. Anat Rec (Hoboken) 2019; 303:544-555. [PMID: 30874365 DOI: 10.1002/ar.24115] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/15/2018] [Revised: 08/23/2018] [Accepted: 09/05/2018] [Indexed: 11/08/2022]
Abstract
Hereditary deafness is often a neurosensory disorder and affects the quality of life of humans. Only three X-linked genes (POU class 3 homeobox 4 (POU3F4), phosphoribosyl pyrophosphate synthetase 1 (PRPS1), and small muscle protein X-linked (SMPX)) are known to be involved in nonsyndromic hearing loss. Four PRPS1 missense mutations have been found to associate with X-linked nonsyndromic sensorineural deafness (DFNX1/DFN2) in humans. However, a causative relationship between PRPS1 mutations and hearing loss in humans has not been well studied in any animal model. Phosphoribosyl pyrophosphate synthetase 1 (PRS-I) is highly conserved in vertebrate taxa. In this study, we used the zebrafish as a model to investigate the auditory role of zebrafish orthologs (prps1a and prps1b) of the human PRPS1 gene with whole mount in situ hybridization, reverse transcription polymerase chain reaction, phenotypic screening, confocal imaging, and electrophysiological methods. We found that both prps1a and prps1b genes were expressed in the inner ear of zebrafish. Splice-blocking antisense morpholino oligonucleotides (MO1 and MO2) caused exon-2 skip and intron-2 retention of prps1a and exon-2 skip and intron-1 retention of prps1b to knock down functions of the genes, respectively. MO1 and MO2 morphants had smaller otic vesicles and otoliths, fewer inner ear hair cells, and lower microphonic response amplitude and sensitivity than control zebrafish. Therefore, knockdown of either prps1a or prps1b resulted in significant sensorineural hearing loss in zebrafish. We conclude that the prps1 genes are essential for hearing in zebrafish, which has the potential to help us understand the biology of human deafness DFNX1/DFN2. Anat Rec, 303:544-555, 2020. © 2019 American Association for Anatomy.
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Affiliation(s)
| | - Bing Zou
- Department of Biology, University of Miami, Coral Gables, Florida.,Department of Otolaryngology, University of Miami Miller School of Medicine, Miami, Florida
| | - M'hamed Grati
- Department of Otolaryngology, University of Miami Miller School of Medicine, Miami, Florida
| | - Denise Yan
- Department of Otolaryngology, University of Miami Miller School of Medicine, Miami, Florida
| | - Rahul Mittal
- Department of Otolaryngology, University of Miami Miller School of Medicine, Miami, Florida
| | - Qi Yao
- Department of Biology, University of Miami, Coral Gables, Florida.,Department of Otolaryngology, University of Miami Miller School of Medicine, Miami, Florida
| | | | - Steven Denyer
- Department of Biology, University of Miami, Coral Gables, Florida
| | - Xue Zhong Liu
- Department of Otolaryngology, University of Miami Miller School of Medicine, Miami, Florida.,Department of Otolaryngology, Xiangya Hospital, Central South University, Changsha, People's Republic of China
| | - Zhongmin Lu
- Department of Biology, University of Miami, Coral Gables, Florida.,Department of Otolaryngology, University of Miami Miller School of Medicine, Miami, Florida.,Neuroscience Program, University of Miami, Miami, Florida.,International Center for Marine Studies, Shanghai Ocean University, Shanghai, People's Republic of China
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53
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Disruption of Telomerase RNA Maturation Kinetics Precipitates Disease. Mol Cell 2019; 74:688-700.e3. [PMID: 30930056 DOI: 10.1016/j.molcel.2019.02.033] [Citation(s) in RCA: 39] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/14/2018] [Revised: 01/07/2019] [Accepted: 02/21/2019] [Indexed: 01/16/2023]
Abstract
Mutations in RNA-processing enzymes are increasingly linked to human disease. Telomerase RNA and related noncoding RNAs require 3' end-processing steps, including oligoadenylation. Germline mutations in poly(A)ribonuclease (PARN) cause accumulation of extended human telomerase RNA (hTR) species and precipitate dyskeratosis congenita and pulmonary fibrosis. Here, we develop nascent RNAend-seq to measure processing rates of RNA precursors. We find that mature hTR derives from extended precursors but that in PARN-mutant cells hTR maturation kinetically stalls and unprocessed precursors are degraded. Loss of poly(A)polymerase PAPD5 in PARN-mutant cells accelerates hTR maturation and restores hTR processing, indicating that oligoadenylation and deadenylation set rates of hTR maturation. The H/ACA domain mediates hTR maturation by precisely defining the 3' end, recruiting poly(A)polymerase activity, and conferring sensitivity to PARN regulation. These data reveal a feedforward circuit in which post-transcriptional oligoadenylation controls RNA maturation kinetics. Similar alterations in RNA processing rates may contribute to mechanisms of RNA-based human disease.
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Warkocki Z, Liudkovska V, Gewartowska O, Mroczek S, Dziembowski A. Terminal nucleotidyl transferases (TENTs) in mammalian RNA metabolism. Philos Trans R Soc Lond B Biol Sci 2018; 373:rstb.2018.0162. [PMID: 30397099 PMCID: PMC6232586 DOI: 10.1098/rstb.2018.0162] [Citation(s) in RCA: 36] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 10/01/2018] [Indexed: 12/15/2022] Open
Abstract
In eukaryotes, almost all RNA species are processed at their 3′ ends and most mRNAs are polyadenylated in the nucleus by canonical poly(A) polymerases. In recent years, several terminal nucleotidyl transferases (TENTs) including non-canonical poly(A) polymerases (ncPAPs) and terminal uridyl transferases (TUTases) have been discovered. In contrast to canonical polymerases, TENTs' functions are more diverse; some, especially TUTases, induce RNA decay while others, such as cytoplasmic ncPAPs, activate translationally dormant deadenylated mRNAs. The mammalian genome encodes 11 different TENTs. This review summarizes the current knowledge about the functions and mechanisms of action of these enzymes. This article is part of the theme issue ‘5′ and 3′ modifications controlling RNA degradation’.
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Affiliation(s)
- Zbigniew Warkocki
- Department of RNA Metabolism, Institute of Bioorganic Chemistry, Polish Academy of Sciences, Noskowskiego 12/14, Poznan, Poland
| | - Vladyslava Liudkovska
- Laboratory of RNA Biology and Functional Genomics, Institute of Biochemistry and Biophysics, Polish Academy of Sciences, Pawinskiego 5a, 02-106 Warsaw, Poland.,Institute of Genetics and Biotechnology, Faculty of Biology, University of Warsaw, Pawinskiego 5a, 02-106 Warsaw, Poland
| | - Olga Gewartowska
- Laboratory of RNA Biology and Functional Genomics, Institute of Biochemistry and Biophysics, Polish Academy of Sciences, Pawinskiego 5a, 02-106 Warsaw, Poland.,Institute of Genetics and Biotechnology, Faculty of Biology, University of Warsaw, Pawinskiego 5a, 02-106 Warsaw, Poland
| | - Seweryn Mroczek
- Laboratory of RNA Biology and Functional Genomics, Institute of Biochemistry and Biophysics, Polish Academy of Sciences, Pawinskiego 5a, 02-106 Warsaw, Poland.,Institute of Genetics and Biotechnology, Faculty of Biology, University of Warsaw, Pawinskiego 5a, 02-106 Warsaw, Poland
| | - Andrzej Dziembowski
- Laboratory of RNA Biology and Functional Genomics, Institute of Biochemistry and Biophysics, Polish Academy of Sciences, Pawinskiego 5a, 02-106 Warsaw, Poland .,Institute of Genetics and Biotechnology, Faculty of Biology, University of Warsaw, Pawinskiego 5a, 02-106 Warsaw, Poland
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55
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Hughes KL, Abshire ET, Goldstrohm AC. Regulatory roles of vertebrate Nocturnin: insights and remaining mysteries. RNA Biol 2018; 15:1255-1267. [PMID: 30257600 PMCID: PMC6284557 DOI: 10.1080/15476286.2018.1526541] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022] Open
Abstract
Post-transcriptional control of messenger RNA (mRNA) is an important layer of gene regulation that modulates mRNA decay, translation, and localization. Eukaryotic mRNA decay begins with the catalytic removal of the 3' poly-adenosine tail by deadenylase enzymes. Multiple deadenylases have been identified in vertebrates and are known to have distinct biological roles; among these proteins is Nocturnin, which has been linked to circadian biology, adipogenesis, osteogenesis, and obesity. Multiple studies have investigated Nocturnin's involvement in these processes; however, a full understanding of its molecular function remains elusive. Recent studies have provided new insights by identifying putative Nocturnin-regulated mRNAs in mice and by determining the structure and regulatory activities of human Nocturnin. This review seeks to integrate these new discoveries into our understanding of Nocturnin's regulatory functions and highlight the important remaining unanswered questions surrounding its regulation, biochemical activities, protein partners, and target mRNAs.
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Affiliation(s)
- Kelsey L Hughes
- a Department of Biochemistry, Molecular Biology and Biophysics , University of Minnesota , Minneapolis , MN , USA
| | - Elizabeth T Abshire
- a Department of Biochemistry, Molecular Biology and Biophysics , University of Minnesota , Minneapolis , MN , USA.,b Department of Biological Chemistry , University of Michigan , Ann Arbor , MI , USA
| | - Aaron C Goldstrohm
- a Department of Biochemistry, Molecular Biology and Biophysics , University of Minnesota , Minneapolis , MN , USA
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56
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Schaffer AE, Breuss MW, Caglayan AO, Al-Sanaa N, Al-Abdulwahed HY, Kaymakçalan H, Yılmaz C, Zaki MS, Rosti RO, Copeland B, Baek ST, Musaev D, Scott EC, Ben-Omran T, Kariminejad A, Kayserili H, Mojahedi F, Kara M, Cai N, Silhavy JL, Elsharif S, Fenercioglu E, Barshop BA, Kara B, Wang R, Stanley V, James KN, Nachnani R, Kalur A, Megahed H, Incecik F, Danda S, Alanay Y, Faqeih E, Melikishvili G, Mansour L, Miller I, Sukhudyan B, Chelly J, Dobyns WB, Bilguvar K, Jamra RA, Gunel M, Gleeson JG. Biallelic loss of human CTNNA2, encoding αN-catenin, leads to ARP2/3 complex overactivity and disordered cortical neuronal migration. Nat Genet 2018; 50:1093-1101. [PMID: 30013181 PMCID: PMC6072555 DOI: 10.1038/s41588-018-0166-0] [Citation(s) in RCA: 54] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/19/2017] [Accepted: 05/22/2018] [Indexed: 12/12/2022]
Abstract
Neuronal migration defects, including pachygyria, are among the most severe developmental brain defects in humans. Here, we identify biallelic truncating mutations in CTNNA2, encoding αN-catenin, in patients with a distinct recessive form of pachygyria. CTNNA2 was expressed in human cerebral cortex, and its loss in neurons led to defects in neurite stability and migration. The αN-catenin paralog, αE-catenin, acts as a switch regulating the balance between β-catenin and Arp2/3 actin filament activities1. Loss of αN-catenin did not affect β-catenin signaling, but recombinant αN-catenin interacted with purified actin and repressed ARP2/3 actin-branching activity. The actin-binding domain of αN-catenin or ARP2/3 inhibitors rescued the neuronal phenotype associated with CTNNA2 loss, suggesting ARP2/3 de-repression as a potential disease mechanism. Our findings identify CTNNA2 as the first catenin family member with biallelic mutations in humans, causing a new pachygyria syndrome linked to actin regulation, and uncover a key factor involved in ARP2/3 repression in neurons.
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Affiliation(s)
- Ashleigh E Schaffer
- Department of Neuroscience, Rady Children's Institute for Genomic Medicine, Howard Hughes Medical Institute, University of California, San Diego, San Diego, CA, USA.
- Department of Genetics and Genome Sciences, Case Western Reserve University, Cleveland, OH, USA.
| | - Martin W Breuss
- Department of Neuroscience, Rady Children's Institute for Genomic Medicine, Howard Hughes Medical Institute, University of California, San Diego, San Diego, CA, USA
| | - Ahmet Okay Caglayan
- Departments of Neurosurgery, Neurobiology, and Genetics, Yale University School of Medicine, New Haven, CT, USA
- Department of Medical Genetics, Istanbul Bilim University, Istanbul, Turkey
| | - Nouriya Al-Sanaa
- Department of Pediatrics, Johns Hopkins Aramco Healthcare, Dhahran, Saudi Arabia
| | - Hind Y Al-Abdulwahed
- Department of Pediatrics, Johns Hopkins Aramco Healthcare, Dhahran, Saudi Arabia
| | - Hande Kaymakçalan
- Department of Pediatrics, Istanbul Bilim University, Istanbul, Turkey
| | - Cahide Yılmaz
- Department of Pediatrics, Yıldırım Beyazıt University, Ankara, Turkey
| | - Maha S Zaki
- Clinical Genetics Department, Human Genetics and Genome Research Division, National Research Centre, Cairo, Egypt
| | - Rasim O Rosti
- Department of Neuroscience, Rady Children's Institute for Genomic Medicine, Howard Hughes Medical Institute, University of California, San Diego, San Diego, CA, USA
| | - Brett Copeland
- Department of Neuroscience, Rady Children's Institute for Genomic Medicine, Howard Hughes Medical Institute, University of California, San Diego, San Diego, CA, USA
| | - Seung Tae Baek
- Department of Neuroscience, Rady Children's Institute for Genomic Medicine, Howard Hughes Medical Institute, University of California, San Diego, San Diego, CA, USA
| | - Damir Musaev
- Department of Neuroscience, Rady Children's Institute for Genomic Medicine, Howard Hughes Medical Institute, University of California, San Diego, San Diego, CA, USA
| | - Eric C Scott
- Department of Neuroscience, Rady Children's Institute for Genomic Medicine, Howard Hughes Medical Institute, University of California, San Diego, San Diego, CA, USA
| | - Tawfeg Ben-Omran
- Clinical and Metabolic Genetics Section, Department of Pediatrics, Hamad Medical Corporation, Doha, Qatar
| | | | - Hulya Kayserili
- Department of Medical Genetics, Koç University School of Medicine, Istanbul, Turkey
| | | | - Majdi Kara
- University of Tripoli, Tripoli Children's Hospital, Tripoli, Libya
| | - Na Cai
- Department of Neuroscience, Rady Children's Institute for Genomic Medicine, Howard Hughes Medical Institute, University of California, San Diego, San Diego, CA, USA
| | - Jennifer L Silhavy
- Department of Neuroscience, Rady Children's Institute for Genomic Medicine, Howard Hughes Medical Institute, University of California, San Diego, San Diego, CA, USA
| | - Seham Elsharif
- University of Tripoli, Tripoli Children's Hospital, Tripoli, Libya
| | - Elif Fenercioglu
- L.E.S. Mikrogen Genetic Diseases Diagnosis Center, Istanbul, Turkey
| | - Bruce A Barshop
- Department of Pediatrics, Biochemical Genetics Program, University of California, San Diego, San Diego, CA, USA
| | - Bulent Kara
- Department of Pediatric Neurology, Kocaeli University, Kocaeli, Turkey
| | - Rengang Wang
- Department of Neuroscience, Rady Children's Institute for Genomic Medicine, Howard Hughes Medical Institute, University of California, San Diego, San Diego, CA, USA
| | - Valentina Stanley
- Department of Neuroscience, Rady Children's Institute for Genomic Medicine, Howard Hughes Medical Institute, University of California, San Diego, San Diego, CA, USA
| | - Kiely N James
- Department of Neuroscience, Rady Children's Institute for Genomic Medicine, Howard Hughes Medical Institute, University of California, San Diego, San Diego, CA, USA
| | - Rahul Nachnani
- Department of Neuroscience, Rady Children's Institute for Genomic Medicine, Howard Hughes Medical Institute, University of California, San Diego, San Diego, CA, USA
| | - Aneesha Kalur
- Department of Genetics and Genome Sciences, Case Western Reserve University, Cleveland, OH, USA
| | - Hisham Megahed
- Clinical Genetics Department, Human Genetics and Genome Research Division, National Research Centre, Cairo, Egypt
| | - Faruk Incecik
- Department of Pediatric Neurology, Cukurova University, Adana, Turkey
| | - Sumita Danda
- Department of Clinical Genetics, Christian Medical College and Hospital, Vellore, India
| | - Yasemin Alanay
- Pediatric Genetics Unit, Department of Pediatrics, Acibadem Mehmet Ali Aydinlar University, Istanbul, Turkey
| | - Eissa Faqeih
- Section of Medical Genetics, Department of Pediatrics, King Fahad Medical City, Children's Hospital, Riyadh, Saudi Arabia
| | | | - Lobna Mansour
- Pediatric Department, Neuropediatric Unit, Cairo University Children's Hospital, Cairo, Egypt
| | - Ian Miller
- Neurology Department, Nicklaus Children's Hospital, Miami, FL, USA
| | - Biayna Sukhudyan
- Arabkir Joint Medical Center and Institute of Child and Adolescent Health, Yerevan, Armenia
| | - Jamel Chelly
- Institut Cochin, Université Paris-Descartes, CNRS (UMR 8104), Paris, France
| | - William B Dobyns
- Departments of Pediatrics and Neurology, University of Washington, Seattle, WA, USA
| | - Kaya Bilguvar
- Departments of Neurosurgery, Neurobiology, and Genetics, Yale University School of Medicine, New Haven, CT, USA
| | - Rami Abou Jamra
- Institute of Human Genetics, University of Leipzig Hospitals and Clinics, Leipzig, Germany
| | - Murat Gunel
- Departments of Neurosurgery, Neurobiology, and Genetics, Yale University School of Medicine, New Haven, CT, USA
| | - Joseph G Gleeson
- Department of Neuroscience, Rady Children's Institute for Genomic Medicine, Howard Hughes Medical Institute, University of California, San Diego, San Diego, CA, USA.
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57
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van Dijk T, Baas F, Barth PG, Poll-The BT. What's new in pontocerebellar hypoplasia? An update on genes and subtypes. Orphanet J Rare Dis 2018; 13:92. [PMID: 29903031 PMCID: PMC6003036 DOI: 10.1186/s13023-018-0826-2] [Citation(s) in RCA: 88] [Impact Index Per Article: 14.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/29/2017] [Accepted: 05/16/2018] [Indexed: 12/25/2022] Open
Abstract
Background Pontocerebellar hypoplasia (PCH) describes a rare, heterogeneous group of neurodegenerative disorders mainly with a prenatal onset. Patients have severe hypoplasia or atrophy of cerebellum and pons, with variable involvement of supratentorial structures, motor and cognitive impairments. Based on distinct clinical features and genetic causes, current classification comprises 11 types of PCH. Main text In this review we describe the clinical, neuroradiological and genetic characteristics of the different PCH subtypes, summarize the differential diagnosis and reflect on potential disease mechanisms in PCH. Seventeen PCH-related genes are now listed in the OMIM database, most of them have a function in RNA processing or translation. It is unknown why defects in these apparently ubiquitous processes result in a brain-specific phenotype. Conclusions Many new PCH related genes and phenotypes have been described due to the appliance of next generation sequencing techniques. By including such a broad range of phenotypes, including non-degenerative and postnatal onset disorders, the current classification gives rise to confusion. Despite the discovery of new pathways involved in PCH, treatment is still symptomatic. However, correct diagnosis of PCH is important to provide suitable care and counseling regarding prognosis, and offer appropriate (prenatal) genetic testing to families.
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Affiliation(s)
- Tessa van Dijk
- Department of Clinical Genetics, Academic Medical Center, Amsterdam, The Netherlands.,Department of Clinical Genetics, Leiden University Medical Center, Leiden, The Netherlands
| | - Frank Baas
- Department of Clinical Genetics, Leiden University Medical Center, Leiden, The Netherlands
| | - Peter G Barth
- Department of Pediatric Neurology, Academic Medical Center, Amsterdam, The Netherlands
| | - Bwee Tien Poll-The
- Department of Pediatric Neurology, Academic Medical Center, Amsterdam, The Netherlands.
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58
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Burns DT, Donkervoort S, Müller JS, Knierim E, Bharucha-Goebel D, Faqeih EA, Bell SK, AlFaifi AY, Monies D, Millan F, Retterer K, Dyack S, MacKay S, Morales-Gonzalez S, Giunta M, Munro B, Hudson G, Scavina M, Baker L, Massini TC, Lek M, Hu Y, Ezzo D, AlKuraya FS, Kang PB, Griffin H, Foley AR, Schuelke M, Horvath R, Bönnemann CG. Variants in EXOSC9 Disrupt the RNA Exosome and Result in Cerebellar Atrophy with Spinal Motor Neuronopathy. Am J Hum Genet 2018; 102:858-873. [PMID: 29727687 PMCID: PMC5986733 DOI: 10.1016/j.ajhg.2018.03.011] [Citation(s) in RCA: 57] [Impact Index Per Article: 9.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2017] [Accepted: 03/06/2018] [Indexed: 12/30/2022] Open
Abstract
The exosome is a conserved multi-protein complex that is essential for correct RNA processing. Recessive variants in exosome components EXOSC3, EXOSC8, and RBM7 cause various constellations of pontocerebellar hypoplasia (PCH), spinal muscular atrophy (SMA), and central nervous system demyelination. Here, we report on four unrelated affected individuals with recessive variants in EXOSC9 and the effect of the variants on the function of the RNA exosome in vitro in affected individuals' fibroblasts and skeletal muscle and in vivo in zebrafish. The clinical presentation was severe, early-onset, progressive SMA-like motor neuronopathy, cerebellar atrophy, and in one affected individual, congenital fractures of the long bones. Three affected individuals of different ethnicity carried the homozygous c.41T>C (p.Leu14Pro) variant, whereas one affected individual was compound heterozygous for c.41T>C (p.Leu14Pro) and c.481C>T (p.Arg161∗). We detected reduced EXOSC9 in fibroblasts and skeletal muscle and observed a reduction of the whole multi-subunit exosome complex on blue-native polyacrylamide gel electrophoresis. RNA sequencing of fibroblasts and skeletal muscle detected significant >2-fold changes in genes involved in neuronal development and cerebellar and motor neuron degeneration, demonstrating the widespread effect of the variants. Morpholino oligonucleotide knockdown and CRISPR/Cas9-mediated mutagenesis of exosc9 in zebrafish recapitulated aspects of the human phenotype, as they have in other zebrafish models of exosomal disease. Specifically, portions of the cerebellum and hindbrain were absent, and motor neurons failed to develop and migrate properly. In summary, we show that variants in EXOSC9 result in a neurological syndrome combining cerebellar atrophy and spinal motoneuronopathy, thus expanding the list of human exosomopathies.
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59
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Clinical and genetic spectrum of AMPD2-related pontocerebellar hypoplasia type 9. Eur J Hum Genet 2018; 26:695-708. [PMID: 29463858 DOI: 10.1038/s41431-018-0098-2] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/21/2017] [Revised: 12/28/2017] [Accepted: 01/09/2018] [Indexed: 11/08/2022] Open
Abstract
Pontocerebellar hypoplasia (PCH) represents a group of autosomal-recessive progressive neurodegenerative disorders of prenatal onset. Eleven PCH subtypes are classified according to clinical, neuroimaging and genetic findings. Individuals with PCH type 9 (PCH9) have a unique combination of postnatal microcephaly, hypoplastic cerebellum and pons, and hypoplastic or absent corpus callosum. PCH9 is caused by biallelic variants in AMPD2 encoding adenosine monophosphate deaminase 2; however, a homozygous AMPD2 frameshift variant has recently been reported in two family members with spastic paraplegia type 63 (SPG63). We identified homozygous or compound heterozygous AMPD2 variants in eight PCH-affected individuals from six families. The eight variants likely affect function and comprise one frameshift, one nonsense and six missense variants; seven of which were novel. The main clinical manifestations in the eight new patients and 17 previously reported individuals with biallelic AMPD2 variants were postnatal microcephaly, severe global developmental delay, spasticity, and central visual impairment. Brain imaging data identified hypomyelination, hypoplasia of the cerebellum and pons, atrophy of the cerebral cortex, complete or partial agenesis of the corpus callosum and the "figure 8" shape of the hypoplastic midbrain as consistent features. We broaden the AMPD2-related clinical spectrum by describing one individual without microcephaly and absence of the characteristic "figure 8" shape of the midbrain. The existence of various AMPD2 isoforms with different functions possibly explains the variability in phenotypes associated with AMPD2 variants: variants leaving some of the isoforms intact may cause SPG63, while those affecting all isoforms may result in the severe and early-onset PCH9.
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60
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Small-molecule flunarizine increases SMN protein in nuclear Cajal bodies and motor function in a mouse model of spinal muscular atrophy. Sci Rep 2018; 8:2075. [PMID: 29391529 PMCID: PMC5794986 DOI: 10.1038/s41598-018-20219-1] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/06/2017] [Accepted: 01/16/2018] [Indexed: 02/07/2023] Open
Abstract
The hereditary neurodegenerative disorder spinal muscular atrophy (SMA) is characterized by the loss of spinal cord motor neurons and skeletal muscle atrophy. SMA is caused by mutations of the survival motor neuron (SMN) gene leading to a decrease in SMN protein levels. The SMN deficiency alters nuclear body formation and whether it can contribute to the disease remains unclear. Here we screen a series of small-molecules on SMA patient fibroblasts and identify flunarizine that accumulates SMN into Cajal bodies, the nuclear bodies important for the spliceosomal small nuclear RNA (snRNA)-ribonucleoprotein biogenesis. Using histochemistry, real-time RT-PCR and behavioural analyses in a mouse model of SMA, we show that along with the accumulation of SMN into Cajal bodies of spinal cord motor neurons, flunarizine treatment modulates the relative abundance of specific spliceosomal snRNAs in a tissue-dependent manner and can improve the synaptic connections and survival of spinal cord motor neurons. The treatment also protects skeletal muscles from cell death and atrophy, raises the neuromuscular junction maturation and prolongs life span by as much as 40 percent (p < 0.001). Our findings provide a functional link between flunarizine and SMA pathology, highlighting the potential benefits of flunarizine in a novel therapeutic perspective against neurodegenerative diseases.
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61
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PARN Modulates Y RNA Stability and Its 3'-End Formation. Mol Cell Biol 2017; 37:MCB.00264-17. [PMID: 28760775 DOI: 10.1128/mcb.00264-17] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/15/2017] [Accepted: 07/24/2017] [Indexed: 11/20/2022] Open
Abstract
Loss-of-function mutations in 3'-to-5' exoribonucleases have been implicated in hereditary human diseases. For example, PARN mutations cause a severe form of dyskeratosis congenita (DC), wherein PARN deficiency leads to human telomerase RNA instability. Since the DC phenotype in PARN patients is even more severe than that of loss-of-function alleles in telomerase components, we hypothesized that PARN would also be required for the stability of other RNAs. Here, we show that PARN depletion reduces the levels of abundant human Y RNAs, which might contribute to the severe phenotype of DC observed in patients. Depletion of PAPD5 or the cytoplasmic exonuclease DIS3L rescues the effect of PARN depletion on Y RNA levels, suggesting that PARN stabilizes Y RNAs by removing oligoadenylated tails added by PAPD5, which would otherwise recruit DIS3L for Y RNA degradation. Through deep sequencing of 3' ends, we provide evidence that PARN can also deadenylate the U6 and RMRP RNAs without affecting their levels. Moreover, we observed widespread posttranscriptional oligoadenylation, uridylation, and guanylation of U6 and Y RNA 3' ends, suggesting that in mammalian cells, the formation of a 3' end for noncoding RNAs can be a complex process governed by the activities of various 3'-end polymerases and exonucleases.
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Homozygous Mutations in TBC1D23 Lead to a Non-degenerative Form of Pontocerebellar Hypoplasia. Am J Hum Genet 2017; 101:441-450. [PMID: 28823706 DOI: 10.1016/j.ajhg.2017.07.015] [Citation(s) in RCA: 39] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/01/2017] [Accepted: 07/17/2017] [Indexed: 01/12/2023] Open
Abstract
Pontocerebellar hypoplasia (PCH) represents a group of recessive developmental disorders characterized by impaired growth of the pons and cerebellum, which frequently follows a degenerative course. Currently, there are 10 partially overlapping clinical subtypes and 13 genes known mutated in PCH. Here, we report biallelic TBC1D23 mutations in six individuals from four unrelated families manifesting a non-degenerative form of PCH. In addition to reduced volume of pons and cerebellum, affected individuals had microcephaly, psychomotor delay, and ataxia. In zebrafish, tbc1d23 morphants replicated the human phenotype showing hindbrain volume loss. TBC1D23 localized at the trans-Golgi and was regulated by the small GTPases Arl1 and Arl8, suggesting a role in trans-Golgi membrane trafficking. Altogether, this study provides a causative link between TBC1D23 mutations and PCH and suggests a less severe clinical course than other PCH subtypes.
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Adam MP, Vilain E. Emerging issues in disorders/differences of sex development (DSD). AMERICAN JOURNAL OF MEDICAL GENETICS PART C-SEMINARS IN MEDICAL GENETICS 2017; 175:249-252. [PMID: 28577349 DOI: 10.1002/ajmg.c.31564] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/29/2017] [Accepted: 05/01/2017] [Indexed: 11/10/2022]
Abstract
Disorders/Differences of Sex Development (DSD), as defined by the 2006 Consensus Statement, are "congenital conditions in which development of chromosomal, gonadal, or anatomic sex is atypical." They represent a spectrum of chronic medical conditions collectively affecting about 1% of the population and are associated with increased risk of infertility, cancer, and psychosocial distress. Clinical management in DSD is subject to multiple controversies about gender assignment, the timing and appropriateness of genital surgery and the approach to disclosure. There is dissent within and between stakeholders (healthcare providers, advocacy groups, families) regarding what constitutes optimal care. This special issue investigates the progress made as well as the uncertainties remaining a decade after the consensus statement and the gaps to be filled by future research and improved clinical practice. It discusses the increasing intricacy of genetic variant interpretation in the era of next-generation sequencing and the associated complexity of phenotypic variability. The issue tackles ethical dilemmas and the complicated decision-making process of assignment of sex of rearing at birth in cases of 5-alpha reductase type 2 deficiency, surveys delivery of clinical services in the United States, discusses challenges of interdisciplinary care and of educating patients and parents about DSD,and reviews the factors predisposing to gonadal tumor and their consequences on clinical management.
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Affiliation(s)
- Margaret P Adam
- Department of Pediatrics, University of Washington School of Medicine, Seattle, Washington
| | - Eric Vilain
- Departments of Human Genetics, Urology, and Pediatrics, David Geffen School of Medicine, University of California, Los Angeles, California
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Oegema R, Baillat D, Schot R, van Unen LM, Brooks A, Kia SK, Hoogeboom AJM, Xia Z, Li W, Cesaroni M, Lequin MH, van Slegtenhorst M, Dobyns WB, de Coo IFM, Verheijen FW, Kremer A, van der Spek PJ, Heijsman D, Wagner EJ, Fornerod M, Mancini GMS. Human mutations in integrator complex subunits link transcriptome integrity to brain development. PLoS Genet 2017; 13:e1006809. [PMID: 28542170 PMCID: PMC5466333 DOI: 10.1371/journal.pgen.1006809] [Citation(s) in RCA: 54] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/07/2016] [Revised: 06/09/2017] [Accepted: 05/09/2017] [Indexed: 02/06/2023] Open
Abstract
Integrator is an RNA polymerase II (RNAPII)-associated complex that was recently identified to have a broad role in both RNA processing and transcription regulation. Importantly, its role in human development and disease is so far largely unexplored. Here, we provide evidence that biallelic Integrator Complex Subunit 1 (INTS1) and Subunit 8 (INTS8) gene mutations are associated with rare recessive human neurodevelopmental syndromes. Three unrelated individuals of Dutch ancestry showed the same homozygous truncating INTS1 mutation. Three siblings harboured compound heterozygous INTS8 mutations. Shared features by these six individuals are severe neurodevelopmental delay and a distinctive appearance. The INTS8 family in addition presented with neuronal migration defects (periventricular nodular heterotopia). We show that the first INTS8 mutation, a nine base-pair deletion, leads to a protein that disrupts INT complex stability, while the second missense mutation introduces an alternative splice site leading to an unstable messenger. Cells from patients with INTS8 mutations show increased levels of unprocessed UsnRNA, compatible with the INT function in the 3’-end maturation of UsnRNA, and display significant disruptions in gene expression and RNA processing. Finally, the introduction of the INTS8 deletion mutation in P19 cells using genome editing alters gene expression throughout the course of retinoic acid-induced neural differentiation. Altogether, our results confirm the essential role of Integrator to transcriptome integrity and point to the requirement of the Integrator complex in human brain development. Neurodevelopmental disorders often have a genetic cause, however the genes and the underlying mechanisms that are involved are increasingly diverse, pointing to the complexity of brain development. For normal cell function and in general for normal development, mechanisms that regulate gene transcription into mRNA are of outermost importance as proper spatial and temporal expression of key developmentally regulated transcripts is essential. The Integrator complex was recently identified to have a broad role in both RNA processing and transcription regulation. This complex is assembled from at least 14 different subunits and several animal studies have pointed to an important role in development. Nevertheless, studies directly demonstrating the relevance of this complex in human health and development have been lacking until now. We show here that mutations in the Integrator Complex Subunit 1 gene (INTS1) and Subunit 8 gene (INTS8) cause a severe neurodevelopmental syndrome, characterized by profound intellectual disability, epilepsy, spasticity, facial and limb dysmorphism and subtle structural brain abnormalities. While the role of the Integrator complex in neuronal migration has recently been established, we provide evidence that INTS8 mutations lead in vitro to instability of the complex and impaired function. In patients cultured fibroblasts we found evidence for abnormalities in mRNA transcription and processing. In addition, introduction of INTS8 mutations in an in vitro model of retinoic acid-induced neuronal differentiation results also in transcription alterations. Altogether our results suggest an evolutionary conserved requirement of INTS1 and INTS8 in brain development.
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Affiliation(s)
- Renske Oegema
- Department of Clinical Genetics, Erasmus MC University Medical Center, Rotterdam, The Netherlands
| | - David Baillat
- Department of Biochemistry & Molecular Biology, University of Texas Medical Branch, Galveston TX, United States of America
| | - Rachel Schot
- Department of Clinical Genetics, Erasmus MC University Medical Center, Rotterdam, The Netherlands
| | - Leontine M. van Unen
- Department of Clinical Genetics, Erasmus MC University Medical Center, Rotterdam, The Netherlands
| | - Alice Brooks
- Department of Clinical Genetics, Erasmus MC University Medical Center, Rotterdam, The Netherlands
| | - Sima Kheradmand Kia
- Department of Clinical Genetics, Erasmus MC University Medical Center, Rotterdam, The Netherlands
| | | | - Zheng Xia
- Division of Biostatistics, Dan L Duncan Cancer Center, Baylor College of Medicine, Houston, TX, United States of America
- Department of Molecular and Cellular Biology, Baylor College of Medicine, Houston, TX, United States of America
| | - Wei Li
- Division of Biostatistics, Dan L Duncan Cancer Center, Baylor College of Medicine, Houston, TX, United States of America
- Department of Molecular and Cellular Biology, Baylor College of Medicine, Houston, TX, United States of America
| | - Matteo Cesaroni
- The Fels Institute, Temple University School of Medicine, Philadelphia, PA, United States of America
| | - Maarten H. Lequin
- Department of Pediatric Radiology, Erasmus MC- Sophia, University Medical Center Rotterdam, The Netherlands
| | - Marjon van Slegtenhorst
- Department of Clinical Genetics, Erasmus MC University Medical Center, Rotterdam, The Netherlands
| | - William B. Dobyns
- Center for Integrative Brain Research, Seattle Children's Research Institute, Seattle, Washington, United States of America
| | - Irenaeus F. M. de Coo
- Department of Neurology, Erasmus MC- Sophia, University Medical Center Rotterdam, The Netherlands
| | - Frans W. Verheijen
- Department of Clinical Genetics, Erasmus MC University Medical Center, Rotterdam, The Netherlands
| | - Andreas Kremer
- Department of Bioinformatics, Erasmus MC, University Medical Center Rotterdam, The Netherlands
| | - Peter J. van der Spek
- Department of Bioinformatics, Erasmus MC, University Medical Center Rotterdam, The Netherlands
| | - Daphne Heijsman
- Department of Clinical Genetics, Erasmus MC University Medical Center, Rotterdam, The Netherlands
- Department of Bioinformatics, Erasmus MC, University Medical Center Rotterdam, The Netherlands
| | - Eric J. Wagner
- Department of Biochemistry & Molecular Biology, University of Texas Medical Branch, Galveston TX, United States of America
- * E-mail: (GMSM); (EJW)
| | - Maarten Fornerod
- Department of Pediatric Oncology and Biochemistry, Erasmus MC, University Medical Center Rotterdam, The Netherlands
| | - Grazia M. S. Mancini
- Department of Clinical Genetics, Erasmus MC University Medical Center, Rotterdam, The Netherlands
- * E-mail: (GMSM); (EJW)
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