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Chattannavar G, Ger M, Balasubramanian J, Mandal S, Jalali S, Takkar B, Pisuchpen P, de Guimaraes TAC, Capasso JE, Kumar Padhy S, Levin AV. Bardet-Biedl syndrome with chorioretinal coloboma: a case series and review of literature. Ophthalmic Genet 2024:1-7. [PMID: 39402987 DOI: 10.1080/13816810.2024.2411257] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/11/2024] [Revised: 09/09/2024] [Accepted: 09/26/2024] [Indexed: 10/19/2024]
Abstract
INTRODUCTION Bardet-Biedl Syndrome (BBS) is a ciliopathy causing developmental defects and progressive retinal dystrophy, whereas choroidal coloboma is a developmental defect causing structural deficiency in the posterior retina. Both are rarely reported together. METHODS Here, we describe the phenotype and genotype of three unrelated patients with co-occurrence of Bardet-Biedl Syndrome and chorioretinal coloboma and review the pertinent literature. RESULTS We describe three unrelated patients, with variable clinical features of Bardet Biedl syndrome. None had family history of BBS or coloboma. Each carried biallelic variants in BBS1, BBS9 and TTC8 gene, respectively. Two had unilateral chorioretinal coloboma, while one had bilateral chorioretinal coloboma. DISCUSSION Although there may be other explanatory factors yet to be revealed, our data suggests that chorioretinal coloboma may be associated with BBS. The Hedgehog (Hh) signaling pathway, an intercellular communicator for development of the eye, is dependent on the primary cilia and plays a crucial role in the closure of the optic fissure. Both disorders therefore involve disruption of primary cilia function which may explain their association.
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Affiliation(s)
- Goura Chattannavar
- Flaum Eye Institute, Ocular Genetics, Golisano Children's Hospital, Rochester, New York, USA
- Jasti V. Ramanamma Children's Eye Care Centre, Child Sight Institute, L. V. Prasad Eye Institute, Hyderabad, India
| | - Marina Ger
- Anant Bajaj Retina Institute, L. V. Prasad eye Institute, Visakhapatnam, India
| | | | - Sohini Mandal
- Department of Ophthalmology, All India Institute of Medical Sciences, New Delhi, India
| | - Subhadra Jalali
- Jasti V. Ramanamma Children's Eye Care Centre, Child Sight Institute, L. V. Prasad Eye Institute, Hyderabad, India
- Srimati Kannuri Santhamma Centre for Vitreoretinal Diseases, Anant Bajaj Retina Institute, L. V. Prasad eye Institute, Hyderabad, India
| | - Brijesh Takkar
- Srimati Kannuri Santhamma Centre for Vitreoretinal Diseases, Anant Bajaj Retina Institute, L. V. Prasad eye Institute, Hyderabad, India
| | - Phattrawan Pisuchpen
- Department of Ophthalmology, Faculty of Medicine, Chulalongkorn University and King Chulalongkorn Memorial Hospital, Bangkok, Thailand
- Division of Academic Affairs, Faculty of Medicine, Chulalongkorn University, Bangkok, Thailand
| | - Thales A C de Guimaraes
- Institute of Ophthalmology, University College London, London, UK
- Department of Ophthalmology, Moorfields Eye Hospital NHS Foundation Trust, London, UK
| | - Jenina E Capasso
- Flaum Eye Institute, Ocular Genetics, Golisano Children's Hospital, Rochester, New York, USA
| | - Srikanta Kumar Padhy
- Vitreo-Retina, Anant Bajaj Retina Institute, L. V. Prasad Eye Institute, Bhubaneswar, India
| | - Alex V Levin
- Flaum Eye Institute, Ocular Genetics, Golisano Children's Hospital, Rochester, New York, USA
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Nishio Y, Kato K, Oishi H, Takahashi Y, Saitoh S. MYCN in human development and diseases. Front Oncol 2024; 14:1417607. [PMID: 38884091 PMCID: PMC11176553 DOI: 10.3389/fonc.2024.1417607] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/15/2024] [Accepted: 05/15/2024] [Indexed: 06/18/2024] Open
Abstract
Somatic mutations in MYCN have been identified across various tumors, playing pivotal roles in tumorigenesis, tumor progression, and unfavorable prognoses. Despite its established notoriety as an oncogenic driver, there is a growing interest in exploring the involvement of MYCN in human development. While MYCN variants have traditionally been associated with Feingold syndrome type 1, recent discoveries highlight gain-of-function variants, specifically p.(Thr58Met) and p.(Pro60Leu), as the cause for megalencephaly-polydactyly syndrome. The elucidation of cellular and murine analytical data from both loss-of-function (Feingold syndrome model) and gain-of-function models (megalencephaly-polydactyly syndrome model) is significantly contributing to a comprehensive understanding of the physiological role of MYCN in human development and pathogenesis. This review discusses the MYCN's functional implications for human development by reviewing the clinical characteristics of these distinct syndromes, Feingold syndrome, and megalencephaly-polydactyly syndrome, providing valuable insights into the understanding of pathophysiological backgrounds of other syndromes associated with the MYCN pathway and the overall comprehension of MYCN's role in human development.
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Affiliation(s)
- Yosuke Nishio
- Department of Pediatrics and Neonatology, Nagoya City University Graduate School of Medical Sciences, Nagoya, Japan
- Department of Pediatrics, Nagoya University Graduate School of Medicine, Nagoya, Japan
- Department of Genetics, Research Institute of Environmental Medicine, Nagoya University, Nagoya, Japan
| | - Kohji Kato
- Department of Pediatrics and Neonatology, Nagoya City University Graduate School of Medical Sciences, Nagoya, Japan
- Department of Pediatrics, Nagoya University Graduate School of Medicine, Nagoya, Japan
- Department of Genetics, Research Institute of Environmental Medicine, Nagoya University, Nagoya, Japan
| | - Hisashi Oishi
- Department of Comparative and Experimental Medicine, Nagoya City University Graduate School of Medical Sciences, Nagoya, Japan
| | - Yoshiyuki Takahashi
- Department of Pediatrics, Nagoya University Graduate School of Medicine, Nagoya, Japan
| | - Shinji Saitoh
- Department of Pediatrics and Neonatology, Nagoya City University Graduate School of Medical Sciences, Nagoya, Japan
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Casey MA, Lusk S, Kwan KM. Eye Morphogenesis in Vertebrates. Annu Rev Vis Sci 2023; 9:221-243. [PMID: 37040791 DOI: 10.1146/annurev-vision-100720-111125] [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] [Indexed: 04/13/2023]
Abstract
Proper eye structure is essential for visual function: Multiple essential eye tissues must take shape and assemble into a precise three-dimensional configuration. Accordingly, alterations to eye structure can lead to pathological conditions of visual impairment. Changes in eye shape can also be adaptive over evolutionary time. Eye structure is first established during development with the formation of the optic cup, which contains the neural retina, retinal pigment epithelium, and lens. This crucial yet deceptively simple hemispherical structure lays the foundation for all later elaborations of the eye. Building on descriptions of the embryonic eye that started with hand drawings and micrographs, the field is beginning to identify mechanisms driving dynamic changes in three-dimensional cell and tissue shape. A combination of molecular genetics, imaging, and pharmacological approaches is defining connections among transcription factors, signaling pathways, and the intracellular machinery governing the emergence of this crucial structure.
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Affiliation(s)
- Macaulie A Casey
- Department of Human Genetics, University of Utah, Salt Lake City, Utah, USA; , ,
| | - Sarah Lusk
- Department of Human Genetics, University of Utah, Salt Lake City, Utah, USA; , ,
| | - Kristen M Kwan
- Department of Human Genetics, University of Utah, Salt Lake City, Utah, USA; , ,
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Malta M, AlMutiri R, Martin CS, Srour M. Holoprosencephaly: Review of Embryology, Clinical Phenotypes, Etiology and Management. CHILDREN 2023; 10:children10040647. [PMID: 37189898 DOI: 10.3390/children10040647] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/15/2023] [Revised: 02/21/2023] [Accepted: 03/27/2023] [Indexed: 03/31/2023]
Abstract
Holoprosencephaly (HPE) is the most common malformation of the prosencephalon in humans. It is characterized by a continuum of structural brain anomalies resulting from the failure of midline cleavage of the prosencephalon. The three classic subtypes of HPE are alobar, semilobar and lobar, although a few additional categories have been added to this original classification. The severity of the clinical phenotype is broad and usually mirrors the radiologic and associated facial features. The etiology of HPE includes both environmental and genetic factors. Disruption of sonic hedgehog (SHH) signaling is the main pathophysiologic mechanism underlying HPE. Aneuploidies, chromosomal copy number variants and monogenic disorders are identified in a large proportion of HPE patients. Despite the high postnatal mortality and the invariable presence of developmental delay, recent advances in diagnostic methods and improvements in patient management over the years have helped to increase survival rates. In this review, we provide an overview of the current knowledge related to HPE, and discuss the classification, clinical features, genetic and environmental etiologies and management.
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Cardozo MJ, Sánchez-Bustamante E, Bovolenta P. Optic cup morphogenesis across species and related inborn human eye defects. Development 2023; 150:dev200399. [PMID: 36714981 PMCID: PMC10110496 DOI: 10.1242/dev.200399] [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] [Indexed: 01/31/2023]
Abstract
The vertebrate eye is shaped as a cup, a conformation that optimizes vision and is acquired early in development through a process known as optic cup morphogenesis. Imaging living, transparent teleost embryos and mammalian stem cell-derived organoids has provided insights into the rearrangements that eye progenitors undergo to adopt such a shape. Molecular and pharmacological interference with these rearrangements has further identified the underlying molecular machineries and the physical forces involved in this morphogenetic process. In this Review, we summarize the resulting scenarios and proposed models that include common and species-specific events. We further discuss how these studies and those in environmentally adapted blind species may shed light on human inborn eye malformations that result from failures in optic cup morphogenesis, including microphthalmia, anophthalmia and coloboma.
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Affiliation(s)
- Marcos J. Cardozo
- Centro de Biología Molecular Severo Ochoa, Consejo Superior de Investigaciones Científicas-Universidad Autónoma de Madrid, c/ Nicolás Cabrera 1, Cantoblanco, Madrid 28049, Spain
- Centro de Investigación Biomédica en Red de Enfermedades Raras (CIBERER), c/ Nicolás Cabrera 1, Cantoblanco, Madrid 28049, Spain
| | - Elena Sánchez-Bustamante
- Centro de Biología Molecular Severo Ochoa, Consejo Superior de Investigaciones Científicas-Universidad Autónoma de Madrid, c/ Nicolás Cabrera 1, Cantoblanco, Madrid 28049, Spain
- Centro de Investigación Biomédica en Red de Enfermedades Raras (CIBERER), c/ Nicolás Cabrera 1, Cantoblanco, Madrid 28049, Spain
| | - Paola Bovolenta
- Centro de Biología Molecular Severo Ochoa, Consejo Superior de Investigaciones Científicas-Universidad Autónoma de Madrid, c/ Nicolás Cabrera 1, Cantoblanco, Madrid 28049, Spain
- Centro de Investigación Biomédica en Red de Enfermedades Raras (CIBERER), c/ Nicolás Cabrera 1, Cantoblanco, Madrid 28049, Spain
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Molecular Bases of Human Malformation Syndromes Involving the SHH Pathway: GLIA/R Balance and Cardinal Phenotypes. Int J Mol Sci 2021; 22:ijms222313060. [PMID: 34884862 PMCID: PMC8657641 DOI: 10.3390/ijms222313060] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/13/2021] [Revised: 11/27/2021] [Accepted: 11/30/2021] [Indexed: 12/11/2022] Open
Abstract
Human hereditary malformation syndromes are caused by mutations in the genes of the signal transduction molecules involved in fetal development. Among them, the Sonic hedgehog (SHH) signaling pathway is the most important, and many syndromes result from its disruption. In this review, we summarize the molecular mechanisms and role in embryonic morphogenesis of the SHH pathway, then classify the phenotype of each malformation syndrome associated with mutations of major molecules in the pathway. The output of the SHH pathway is shown as GLI activity, which is generated by SHH in a concentration-dependent manner, i.e., the sum of activating form of GLI (GLIA) and repressive form of GLI (GLIR). Which gene is mutated and whether the mutation is loss-of-function or gain-of-function determine in which concentration range of SHH the imbalance occurs. In human malformation syndromes, too much or too little GLI activity produces symmetric phenotypes affecting brain size, craniofacial (midface) dysmorphism, and orientation of polydactyly with respect to the axis of the limb. The symptoms of each syndrome can be explained by the GLIA/R balance model.
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Kim SY, Lee SM, Shin J, Lee JE, Kim SJ. Two Cases of Ocular Manifestations in Patients with Microdeletion of the Chromosome 7 Long Arm. JOURNAL OF THE KOREAN OPHTHALMOLOGICAL SOCIETY 2021. [DOI: 10.3341/jkos.2021.62.7.1003] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
Abstract
Purpose: We report ocular manifestations in two patients with 7q microdeletion. Case summary: (Case 1) A 62-day-old male infant was admitted to the ophthalmology outpatient department for ocular examination after being diagnosed with microdeletion of chromosome seven (7q36.2q36.3 deletion) in DNA microarray comparative genomic hybridization (DNA microarray CGH) and fluorescence in situ hybridization (FISH) tests. Fundus examination showed optic disc hypoplasia in both eyes and retinopathy of prematurity, accompanied by retinal hemorrhage in his right eye. Around the age of 24 months, the patient was diagnosed with intermittent exotropia with anisometropia and was prescribed spectacles. (Case 2) A 3-year-old male infant was referred to the ophthalmology clinic to evaluate poor fixation, which was found during rehabilitation therapy for cerebral palsy and developmental delay. Fundus examination showed an increased cup/disc ratio bilaterally. A flash visual evoked potential test indicated a decrease in amplitude in his right eye. Intermittent exotropia of forty prism diopters was observed. DNA microarray CGH and FISH tests performed at another hospital revealed microdeletion of chromosome seven (7q35 microdeletion) and CNTNAP2 gene loss. Conclusions: When genetic anomalies associated with ocular development are identified, it is necessary to detect the ophthalmic abnormalities early and provide the appropriate treatment to allow for the development of normal visual function.
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Pande S, Radhakrishnan P, Shetty NM, Shukla A, Girisha KM. Hedgehog acyl-transferase-related multiple congenital anomalies: Report of an additional family and delineation of the syndrome. Am J Med Genet A 2021; 185:2756-2765. [PMID: 33749989 DOI: 10.1002/ajmg.a.62186] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/08/2020] [Revised: 02/19/2021] [Accepted: 03/09/2021] [Indexed: 11/11/2022]
Abstract
This study includes previous reports of four affected individuals from two unrelated families with hedgehog acyl-transferase (HHAT)-related multiple congenital anomaly syndrome. Microcephaly, small cerebellar vermis, holoprosencephaly, agenesis of corpus callosum, intellectual disability, short stature, skeletal dysplasia, microphthalmia-anophthalmia, and sex reversal constitute the phenotypic spectrum of this condition with variable expression. We report an additional family with three affected conceptuses: two abortuses and one living proband. We did proband-parents trio exome sequencing and identified a biallelic in-frame deletion c.365_367del; (p.Thr122del) in exon 5 of HHAT. With this report, we delineate the phenotype and allelic heterogeneity of the HHAT-related multiple congenital anomaly syndrome.
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Affiliation(s)
- Shruti Pande
- Department of Medical Genetics, Kasturba Medical College, Manipal, Manipal Academy of Higher Education, Manipal, India
| | - Periyasamy Radhakrishnan
- Department of Medical Genetics, Kasturba Medical College, Manipal, Manipal Academy of Higher Education, Manipal, India
| | | | - Anju Shukla
- Department of Medical Genetics, Kasturba Medical College, Manipal, Manipal Academy of Higher Education, Manipal, India
| | - Katta M Girisha
- Department of Medical Genetics, Kasturba Medical College, Manipal, Manipal Academy of Higher Education, Manipal, India
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A 300-kb microduplication of 7q36.3 in a patient with triphalangeal thumb-polysyndactyly syndrome combined with congenital heart disease and optic disc coloboma: a case report. BMC Med Genomics 2020; 13:175. [PMID: 33218365 PMCID: PMC7678048 DOI: 10.1186/s12920-020-00821-x] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/01/2020] [Accepted: 11/09/2020] [Indexed: 12/04/2022] Open
Abstract
Background Triphalangeal thumb-polysyndactyly syndrome (TPT-PS) is a rare well-defined autosomal dominant disorder characterized by long thumbs with three phalanges combined with pre- and postaxial polydactyly/syndactyly of limbs.
By now, the syndrome has been reported in several large families from different ethnic backgrounds, with a high degree of inter- and intrafamilial variability. The genome locus responsible for TPT-PS has been mapped to the 7q36.3 region harboring a long-range sonic hedgehog (SHH) regulatory sequence (ZRS). Both single-nucleotide variants and complete duplications of ZRS were shown to cause TPT-PS and similar limb phenotypes. TPT-PS usually forms as isolated limb pathology not associated with additional malformations, in particular, with cardiovascular abnormalities. Case presentation Here we report on a rare Russian neonatal case of TPT-PS combined with severe congenital heart disease, namely double outlet right ventricle, and microphthalmia with optic disc coloboma. Pedigree analysis revealed TPT-PS of various expressivity in 10 family members throughout five generations, while the cardiac defect and the eye pathology were detected only in the proband. To extend the knowledge on genotype–phenotype spectrum of TPT-PS, the careful clinical and genomic analysis of the family was performed. High-resolution array-based comparative genomic hybridization (array-CGH) revealed a ~ 300 kb microduplication of 7q36.3 locus (arr[GRCh37] 7q36.3(156385810_156684811) × 3) that co-segregated with TPT-PS in the proband and her mother. The duplication encompassed three genes including LMBR1, the intron 5 of which is known to harbor ZRS. Based on whole-exome sequencing data, no additional pathogenic mutations or variants of uncertain clinical significance were found in morbid cardiac genes or genes associated with a microphthalmia/anophthalmia/coloboma spectrum of ocular malformations. Conclusions The results support the previous data, indicating that complete ZRS duplication underlies TPT-PS, and suggest a broader phenotypic impact of the 7q36.3 microduplication. Potential involvement of the 7q36.3 microduplication in the patient’s cardiac and eye malformations is discussed. However, the contribution of some additional genetic/epigenetic factors to the complex patient`s phenotype cannot be excluded entirely. Further comprehensive functional studies are needed to prove the possible involvement of the 7q36.3 locus in congenital heart disease and eye pathology.
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Weigele J, Bohnsack BL. Genetics Underlying the Interactions between Neural Crest Cells and Eye Development. J Dev Biol 2020; 8:jdb8040026. [PMID: 33182738 PMCID: PMC7712190 DOI: 10.3390/jdb8040026] [Citation(s) in RCA: 20] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/16/2020] [Revised: 11/03/2020] [Accepted: 11/07/2020] [Indexed: 12/14/2022] Open
Abstract
The neural crest is a unique, transient stem cell population that is critical for craniofacial and ocular development. Understanding the genetics underlying the steps of neural crest development is essential for gaining insight into the pathogenesis of congenital eye diseases. The neural crest cells play an under-appreciated key role in patterning the neural epithelial-derived optic cup. These interactions between neural crest cells within the periocular mesenchyme and the optic cup, while not well-studied, are critical for optic cup morphogenesis and ocular fissure closure. As a result, microphthalmia and coloboma are common phenotypes in human disease and animal models in which neural crest cell specification and early migration are disrupted. In addition, neural crest cells directly contribute to numerous ocular structures including the cornea, iris, sclera, ciliary body, trabecular meshwork, and aqueous outflow tracts. Defects in later neural crest cell migration and differentiation cause a constellation of well-recognized ocular anterior segment anomalies such as Axenfeld–Rieger Syndrome and Peters Anomaly. This review will focus on the genetics of the neural crest cells within the context of how these complex processes specifically affect overall ocular development and can lead to congenital eye diseases.
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Affiliation(s)
- Jochen Weigele
- Division of Ophthalmology, Ann & Robert H. Lurie Children’s Hospital of Chicago, 225 E. Chicago Ave, Chicago, IL 60611, USA;
- Department of Ophthalmology, Northwestern University Feinberg School of Medicine, 645 N. Michigan Ave, Chicago, IL 60611, USA
| | - Brenda L. Bohnsack
- Division of Ophthalmology, Ann & Robert H. Lurie Children’s Hospital of Chicago, 225 E. Chicago Ave, Chicago, IL 60611, USA;
- Department of Ophthalmology, Northwestern University Feinberg School of Medicine, 645 N. Michigan Ave, Chicago, IL 60611, USA
- Correspondence: ; Tel.: +1-312-227-6180; Fax: +1-312-227-9411
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Reis LM, Basel D, McCarrier J, Weinberg DV, Semina EV. Compound heterozygous splicing CDON variants result in isolated ocular coloboma. Clin Genet 2020; 98:486-492. [PMID: 32729136 PMCID: PMC8341436 DOI: 10.1111/cge.13824] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/24/2020] [Revised: 07/23/2020] [Accepted: 07/25/2020] [Indexed: 12/20/2022]
Abstract
Ocular coloboma is caused by failure of optic fissure closure during development and recognized as part of the microphthalmia, anophthalmia, and coloboma (MAC) spectrum. While many genes are known to cause colobomatous microphthalmia, relatively few have been reported in coloboma with normal eye size. Genetic analysis including trio exome sequencing and Sanger sequencing was undertaken in a family with two siblings affected with bilateral coloboma of the iris, retina, and choroid. Pathogenic variants in MAC genes were excluded. Trio analysis identified compound heterozygous donor splice site variants in CDON, a cell-surface receptor known to function in the Sonic Hedgehog pathway, c.928 + 1G > A and c.2650 + 1G > T, in both affected individuals. Heterozygous missense and truncating CDON variants are associated with dominant holoprosencephaly (HPE) with incomplete penetrance and Cdon-/- mice display variable HPE and coloboma. A homozygous nonsense allele of uncertain significance was recently identified in a consanguineous patient with coloboma and a second molecular diagnosis. We report the first compound heterozygous variants in CDON as a cause of isolated coloboma. CDON is the first HPE gene identified to cause recessive coloboma. Given the phenotypic overlap, further examination of HPE genes in coloboma is indicated.
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Affiliation(s)
- Linda M Reis
- Department of Pediatrics, Children’s Research Institute, Medical College of Wisconsin and Children’s Wisconsin, Milwaukee, WI 53226
| | - Donald Basel
- Department of Pediatrics, Children’s Research Institute, Medical College of Wisconsin and Children’s Wisconsin, Milwaukee, WI 53226
| | - Julie McCarrier
- Department of Pediatrics, Children’s Research Institute, Medical College of Wisconsin and Children’s Wisconsin, Milwaukee, WI 53226
| | - David V Weinberg
- Department of Ophthalmology and Visual Sciences, Medical College of Wisconsin, Milwaukee, WI 53226
| | - Elena V Semina
- Department of Pediatrics, Children’s Research Institute, Medical College of Wisconsin and Children’s Wisconsin, Milwaukee, WI 53226
- Department of Ophthalmology and Visual Sciences, Medical College of Wisconsin, Milwaukee, WI 53226
- Department of Cell Biology, Neurobiology and Anatomy, Medical College of Wisconsin, Milwaukee, WI 53226
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Sinagoga KL, Larimer-Picciani AM, George SM, Spencer SA, Lister JA, Gross JM. Mitf-family transcription factor function is required within cranial neural crest cells to promote choroid fissure closure. Development 2020; 147:dev187047. [PMID: 32541011 PMCID: PMC7375471 DOI: 10.1242/dev.187047] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/08/2019] [Accepted: 05/29/2020] [Indexed: 12/13/2022]
Abstract
A crucial step in eye development is the closure of the choroid fissure (CF), a transient structure in the ventral optic cup through which vasculature enters the eye and ganglion cell axons exit. Although many factors have been identified that function during CF closure, the molecular and cellular mechanisms mediating this process remain poorly understood. Failure of CF closure results in colobomas. Recently, MITF was shown to be mutated in a subset of individuals with colobomas, but how MITF functions during CF closure is unknown. To address this issue, zebrafish with mutations in mitfa and tfec, two members of the Mitf family of transcription factors, were analyzed and their functions during CF closure determined. mitfa;tfec mutants possess severe colobomas and our data demonstrate that Mitf activity is required within cranial neural crest cells (cNCCs) during CF closure. In the absence of Mitf function, cNCC migration and localization in the optic cup are perturbed. These data shed light on the cellular mechanisms underlying colobomas in individuals with MITF mutations and identify a novel role for Mitf function in cNCCs during CF closure.
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Affiliation(s)
- Katie L Sinagoga
- Departments of Ophthalmology and Developmental Biology, Louis J. Fox Center for Vision Restoration, The University of Pittsburgh School of Medicine, Pittsburgh, PA 15213, USA
| | - Alessandra M Larimer-Picciani
- Departments of Ophthalmology and Developmental Biology, Louis J. Fox Center for Vision Restoration, The University of Pittsburgh School of Medicine, Pittsburgh, PA 15213, USA
| | - Stephanie M George
- Departments of Ophthalmology and Developmental Biology, Louis J. Fox Center for Vision Restoration, The University of Pittsburgh School of Medicine, Pittsburgh, PA 15213, USA
| | - Samantha A Spencer
- Department of Human and Molecular Genetics, Virginia Commonwealth University School of Medicine, Richmond, VA 23298, USA
| | - James A Lister
- Department of Human and Molecular Genetics, Virginia Commonwealth University School of Medicine, Richmond, VA 23298, USA
| | - Jeffrey M Gross
- Departments of Ophthalmology and Developmental Biology, Louis J. Fox Center for Vision Restoration, The University of Pittsburgh School of Medicine, Pittsburgh, PA 15213, USA
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Arribat Y, Mysiak KS, Lescouzères L, Boizot A, Ruiz M, Rossel M, Bomont P. Sonic Hedgehog repression underlies gigaxonin mutation-induced motor deficits in giant axonal neuropathy. J Clin Invest 2020; 129:5312-5326. [PMID: 31503551 DOI: 10.1172/jci129788] [Citation(s) in RCA: 17] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2019] [Accepted: 08/28/2019] [Indexed: 12/11/2022] Open
Abstract
Growing evidence shows that alterations occurring at early developmental stages contribute to symptoms manifested in adulthood in the setting of neurodegenerative diseases. Here, we studied the molecular mechanisms causing giant axonal neuropathy (GAN), a severe neurodegenerative disease due to loss-of-function of the gigaxonin-E3 ligase. We showed that gigaxonin governs Sonic Hedgehog (Shh) induction, the developmental pathway patterning the dorso-ventral axis of the neural tube and muscles, by controlling the degradation of the Shh-bound Patched receptor. Similar to Shh inhibition, repression of gigaxonin in zebrafish impaired motor neuron specification and somitogenesis and abolished neuromuscular junction formation and locomotion. Shh signaling was impaired in gigaxonin-null zebrafish and was corrected by both pharmacological activation of the Shh pathway and human gigaxonin, pointing to an evolutionary-conserved mechanism regulating Shh signaling. Gigaxonin-dependent inhibition of Shh activation was also demonstrated in primary fibroblasts from patients with GAN and in a Shh activity reporter line depleted in gigaxonin. Our findings establish gigaxonin as a key E3 ligase that positively controls the initiation of Shh transduction, and reveal the causal role of Shh dysfunction in motor deficits, thus highlighting the developmental origin of GAN.
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Affiliation(s)
- Yoan Arribat
- ATIP-Avenir team, INM, INSERM, University of Montpellier, Montpellier, France
| | - Karolina S Mysiak
- ATIP-Avenir team, INM, INSERM, University of Montpellier, Montpellier, France
| | - Léa Lescouzères
- ATIP-Avenir team, INM, INSERM, University of Montpellier, Montpellier, France
| | - Alexia Boizot
- ATIP-Avenir team, INM, INSERM, University of Montpellier, Montpellier, France
| | - Maxime Ruiz
- ATIP-Avenir team, INM, INSERM, University of Montpellier, Montpellier, France
| | - Mireille Rossel
- MMDN, University of Montpellier, EPHE, INSERM, U1198, PSL Research University, Montpellier, France
| | - Pascale Bomont
- ATIP-Avenir team, INM, INSERM, University of Montpellier, Montpellier, France
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14
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Lézot F, Corre I, Morice S, Rédini F, Verrecchia F. SHH Signaling Pathway Drives Pediatric Bone Sarcoma Progression. Cells 2020; 9:cells9030536. [PMID: 32110934 PMCID: PMC7140443 DOI: 10.3390/cells9030536] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2020] [Revised: 02/19/2020] [Accepted: 02/23/2020] [Indexed: 02/07/2023] Open
Abstract
Primary bone tumors can be divided into two classes, benign and malignant. Among the latter group, osteosarcoma and Ewing sarcoma are the most prevalent malignant primary bone tumors in children and adolescents. Despite intensive efforts to improve treatments, almost 40% of patients succumb to the disease. Specifically, the clinical outcome for metastatic osteosarcoma or Ewing sarcoma remains poor; less than 30% of patients who present metastases will survive 5 years after initial diagnosis. One common and specific point of these bone tumors is their ability to deregulate bone homeostasis and remodeling and divert them to their benefit. Over the past years, considerable interest in the Sonic Hedgehog (SHH) pathway has taken place within the cancer research community. The activation of this SHH cascade can be done through different ways and, schematically, two pathways can be described, the canonical and the non-canonical. This review discusses the current knowledge about the involvement of the SHH signaling pathway in skeletal development, pediatric bone sarcoma progression and the related therapeutic options that may be possible for these tumors.
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15
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George A, Cogliati T, Brooks BP. Genetics of syndromic ocular coloboma: CHARGE and COACH syndromes. Exp Eye Res 2020; 193:107940. [PMID: 32032630 DOI: 10.1016/j.exer.2020.107940] [Citation(s) in RCA: 18] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/12/2019] [Revised: 01/20/2020] [Accepted: 01/22/2020] [Indexed: 02/07/2023]
Abstract
Optic fissure closure defects result in uveal coloboma, a potentially blinding condition affecting between 0.5 and 2.6 per 10,000 births that may cause up to 10% of childhood blindness. Uveal coloboma is on a phenotypic continuum with microphthalmia (small eye) and anophthalmia (primordial/no ocular tissue), the so-called MAC spectrum. This review gives a brief overview of the developmental biology behind coloboma and its clinical presentation/spectrum. Special attention will be given to two prominent, syndromic forms of coloboma, namely, CHARGE (Coloboma, Heart defect, Atresia choanae, Retarded growth and development, Genital hypoplasia, and Ear anomalies/deafness) and COACH (Cerebellar vermis hypoplasia, Oligophrenia, Ataxia, Coloboma, and Hepatic fibrosis) syndromes. Approaches employed to identify genes involved in optic fissure closure in animal models and recent advances in live imaging of zebrafish eye development are also discussed.
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Affiliation(s)
- Aman George
- Ophthalmic Genetics and Visual Function Branch, National Eye Institute, National Institutes of Health. Bethesda, Maryland, 20892, USA
| | - Tiziana Cogliati
- Ophthalmic Genetics and Visual Function Branch, National Eye Institute, National Institutes of Health. Bethesda, Maryland, 20892, USA
| | - Brian P Brooks
- Ophthalmic Genetics and Visual Function Branch, National Eye Institute, National Institutes of Health. Bethesda, Maryland, 20892, USA.
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16
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Kalaskar VK, Alur RP, Li LK, Thomas JW, Sergeev YV, Blain D, Hufnagel RB, Cogliati T, Brooks BP. High-throughput custom capture sequencing identifies novel mutations in coloboma-associated genes: Mutation in DNA-binding domain of retinoic acid receptor beta affects nuclear localization causing ocular coloboma. Hum Mutat 2019; 41:678-695. [PMID: 31816153 PMCID: PMC7027867 DOI: 10.1002/humu.23954] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/16/2018] [Revised: 10/04/2019] [Accepted: 11/09/2019] [Indexed: 12/11/2022]
Abstract
Uveal coloboma is a potentially blinding congenital ocular malformation caused by the failure of optic fissure closure during the fifth week of human gestation. We performed custom capture high‐throughput screening of 38 known coloboma‐associated genes in 66 families. Suspected causative novel variants were identified in TFAP2A and CHD7, as well as two previously reported variants of uncertain significance in RARB and BMP7. The variant in RARB, unlike previously reported disease mutations in the ligand‐binding domain, was a missense change in the highly conserved DNA‐binding domain predicted to affect the protein's DNA‐binding ability. In vitro studies revealed lower steady‐state protein levels, reduced transcriptional activity, and incomplete nuclear localization of the mutant RARB protein compared with wild‐type. Zebrafish studies showed that human RARB messenger RNA partially reduced the ocular phenotype caused by morpholino knockdown of rarga gene, a zebrafish homolog of human RARB. Our study indicates that sequence alterations in known coloboma genes account for a small percentage of coloboma cases and that mutations in the RARB DNA‐binding domain could result in human disease.
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Affiliation(s)
- Vijay K Kalaskar
- Pediatric, Developmental & Genetic Ophthalmology Section, Ophthalmic Genetics and Visual Function Branch (OGVFB), National Eye Institute (NEI), National Institutes of Health (NIH), Bethesda, Maryland
| | - Ramakrishna P Alur
- Pediatric, Developmental & Genetic Ophthalmology Section, Ophthalmic Genetics and Visual Function Branch (OGVFB), National Eye Institute (NEI), National Institutes of Health (NIH), Bethesda, Maryland
| | - LeeAnn K Li
- Pediatric, Developmental & Genetic Ophthalmology Section, Ophthalmic Genetics and Visual Function Branch (OGVFB), National Eye Institute (NEI), National Institutes of Health (NIH), Bethesda, Maryland
| | - James W Thomas
- National Institutes of Health Intramural Sequencing Center, National Human Genome Research Institute, NIH, Bethesda, Maryland
| | - Yuri V Sergeev
- Protein Biochemistry and Molecular Modeling Group, OGVFB, NEI, NIH, Bethesda, Maryland
| | - Delphine Blain
- Ophthalmic Clinical Genetics Section, OGVFB, NEI, NIH, Bethesda, Maryland
| | - Robert B Hufnagel
- Medical Genetics and Ophthalmic Genomics Unit, OGVFB, NEI, NIH, Bethesda, Maryland
| | - Tiziana Cogliati
- Pediatric, Developmental & Genetic Ophthalmology Section, Ophthalmic Genetics and Visual Function Branch (OGVFB), National Eye Institute (NEI), National Institutes of Health (NIH), Bethesda, Maryland
| | - Brian P Brooks
- Pediatric, Developmental & Genetic Ophthalmology Section, Ophthalmic Genetics and Visual Function Branch (OGVFB), National Eye Institute (NEI), National Institutes of Health (NIH), Bethesda, Maryland.,Ophthalmic Clinical Genetics Section, OGVFB, NEI, NIH, Bethesda, Maryland
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17
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Harding P, Moosajee M. The Molecular Basis of Human Anophthalmia and Microphthalmia. J Dev Biol 2019; 7:jdb7030016. [PMID: 31416264 PMCID: PMC6787759 DOI: 10.3390/jdb7030016] [Citation(s) in RCA: 31] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/19/2019] [Revised: 08/08/2019] [Accepted: 08/08/2019] [Indexed: 12/16/2022] Open
Abstract
Human eye development is coordinated through an extensive network of genetic signalling pathways. Disruption of key regulatory genes in the early stages of eye development can result in aborted eye formation, resulting in an absent eye (anophthalmia) or a small underdeveloped eye (microphthalmia) phenotype. Anophthalmia and microphthalmia (AM) are part of the same clinical spectrum and have high genetic heterogeneity, with >90 identified associated genes. By understanding the roles of these genes in development, including their temporal expression, the phenotypic variation associated with AM can be better understood, improving diagnosis and management. This review describes the genetic and structural basis of eye development, focusing on the function of key genes known to be associated with AM. In addition, we highlight some promising avenues of research involving multiomic approaches and disease modelling with induced pluripotent stem cell (iPSC) technology, which will aid in developing novel therapies.
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Affiliation(s)
| | - Mariya Moosajee
- UCL Institute of Ophthalmology, London EC1V 9EL, UK.
- Moorfields Eye Hospital NHS Foundation Trust, London EC1V 2PD, UK.
- Great Ormond Street Hospital for Children NHS Foundation Trust, London WC1N 3JH, UK.
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18
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An update on the genetics of ocular coloboma. Hum Genet 2019; 138:865-880. [PMID: 31073883 DOI: 10.1007/s00439-019-02019-3] [Citation(s) in RCA: 20] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/09/2018] [Accepted: 04/19/2019] [Indexed: 01/04/2023]
Abstract
Ocular coloboma is an uncommon, but often severe, sight-threatening condition that can be identified from birth. This congenital anomaly is thought to be caused by maldevelopment of optic fissure closure during early eye morphogenesis. It has been causally linked to both inherited (genetic) and environmental influences. In particular, as a consequence of work to identify genetic causes of coloboma, new molecular pathways that control optic fissure closure have now been identified. Many more regulatory mechanisms still await better understanding to inform on the development of potential therapies for patients with this malformation. This review provides an update of known coloboma genes, the pathways they influence and how best to manage the condition. In the age of precision medicine, determining the underlying genetic cause in any given patient is of high importance.
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19
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Ohuchi H, Sato K, Habuta M, Fujita H, Bando T. Congenital eye anomalies: More mosaic than thought? Congenit Anom (Kyoto) 2019; 59:56-73. [PMID: 30039880 DOI: 10.1111/cga.12304] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/21/2018] [Revised: 07/16/2018] [Accepted: 07/17/2018] [Indexed: 12/13/2022]
Abstract
The eye is a sensory organ that primarily captures light and provides the sense of sight, as well as delivering non-visual light information involving biological rhythms and neurophysiological activities to the brain. Since the early 1990s, rapid advances in molecular biology have enabled the identification of developmental genes, genes responsible for human congenital diseases, and relevant genes of mutant animals with various anomalies. In this review, we first look at the development of the eye, and we highlight seminal reports regarding archetypal gene defects underlying three developmental ocular disorders in humans: (1) holoprosencephaly (HPE), with cyclopia being exhibited in the most severe cases; (2) microphthalmia, anophthalmia, and coloboma (MAC) phenotypes; and (3) anterior segment dysgenesis (ASDG), known as Peters anomaly and its related disorders. The recently developed methods, such as next-generation sequencing and genome editing techniques, have aided the discovery of gene mutations in congenital eye diseases and gene functions in normal eye development. Finally, we discuss Pax6-genome edited mosaic eyes and propose that somatic mosaicism in developmental gene mutations should be considered a causal factor for variable phenotypes, sporadic cases, and de novo mutations in human developmental disorders.
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Affiliation(s)
- Hideyo Ohuchi
- Department of Cytology and Histology, Okayama University Graduate School of Medicine, Dentistry and Pharmaceutical Sciences, Okayama, Japan
| | - Keita Sato
- Department of Cytology and Histology, Okayama University Graduate School of Medicine, Dentistry and Pharmaceutical Sciences, Okayama, Japan
| | - Munenori Habuta
- Department of Cytology and Histology, Okayama University Graduate School of Medicine, Dentistry and Pharmaceutical Sciences, Okayama, Japan
| | - Hirofumi Fujita
- Department of Cytology and Histology, Okayama University Graduate School of Medicine, Dentistry and Pharmaceutical Sciences, Okayama, Japan
| | - Tetsuya Bando
- Department of Cytology and Histology, Okayama University Graduate School of Medicine, Dentistry and Pharmaceutical Sciences, Okayama, Japan
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20
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Abdel-Salam GMH, Mazen I, Eid M, Ewida N, Shaheen R, Alkuraya FS. Biallelic novel missense HHAT variant causes syndromic microcephaly and cerebellar-vermis hypoplasia. Am J Med Genet A 2019; 179:1053-1057. [PMID: 30912300 DOI: 10.1002/ajmg.a.61133] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/06/2019] [Revised: 03/07/2019] [Accepted: 03/11/2019] [Indexed: 11/09/2022]
Abstract
We report two siblings with microcephaly, early infantile onset seizures, and cerebellar vermis hypoplasia, in whom whole exome sequencing revealed a novel homozygous missense (c.770T>C, p.[Leu257Pro]) variant in the hedgehog acyl-transferase gene (HHAT), encoding an enzyme required for the attachment of palmitoyl residues that are critical for multimerization and long and short range hedgehog signaling. There is a report of one family with Nivelon-Nivelon-Mabille syndrome in which HHAT was proposed as the likely candidate gene. The phenotypic overlap with the family we report herein provides further evidence implicating HHAT in cerebellar development and the pathogenesis of this rare spectrum.
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Affiliation(s)
- Ghada M H Abdel-Salam
- Clinical Genetics Department, Human Genetics and Genome Research Division, National Research Centre, Cairo, Egypt
| | - Inas Mazen
- Clinical Genetics Department, Human Genetics and Genome Research Division, National Research Centre, Cairo, Egypt
| | - Maha Eid
- Human Cytogenetics Department, Human Genetics and Genome Research Division, National Research Centre, Cairo, Egypt
| | - Nour Ewida
- Department of Genetics, King Faisal Specialist Hospital and Research Center, Riyadh, Saudi Arabia
| | - Ranad Shaheen
- Department of Genetics, King Faisal Specialist Hospital and Research Center, Riyadh, Saudi Arabia
| | - Fowzan S Alkuraya
- Department of Genetics, King Faisal Specialist Hospital and Research Center, Riyadh, Saudi Arabia.,Saudi Human Genome Program, King Abdulaziz City for Science and Technology, Riyadh, Saudi Arabia.,Department of Anatomy and Cell Biology, College of Medicine, Alfaisal University, Riyadh, Saudi Arabia
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21
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Gordon HB, Lusk S, Carney KR, Wirick EO, Murray BF, Kwan KM. Hedgehog signaling regulates cell motility and optic fissure and stalk formation during vertebrate eye morphogenesis. Development 2018; 145:dev.165068. [PMID: 30333214 PMCID: PMC6262791 DOI: 10.1242/dev.165068] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/26/2018] [Accepted: 10/08/2018] [Indexed: 12/18/2022]
Abstract
Establishment of precise three-dimensional tissue structure is vital for organ function. In the visual system, optic fissure and stalk morphogenesis is a crucial yet poorly understood process, disruptions of which can lead to coloboma, a birth defect causing visual impairment. Here, we use four-dimensional imaging, cell tracking, and molecular genetics in zebrafish to define the cell movements underlying normal optic fissure and stalk formation. We determine how these events are disrupted in a coloboma model in which the Hedgehog (Hh) receptor ptch2 is lost, resulting in overactive Hh signaling. In the ptch2 mutant, cells exhibit defective motile behaviors and morphology. Cells that should contribute to the fissure do not arrive at their correct position, and instead contribute to an ectopically large optic stalk. Our results suggest that overactive Hh signaling, through overexpression of downstream transcriptional targets, impairs cell motility underlying optic fissure and stalk formation, via non-cell-autonomous and cell-autonomous mechanisms. More broadly, our cell motility and morphology analyses provide a new framework for studying other coloboma-causing mutations that disrupt optic fissure or stalk formation. Summary: Multidimensional imaging of ptch2 mutant zebrafish uncovers a role for the Hh signaling pathway in regulating the cell and tissue dynamics underlying early eye morphogenesis.
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Affiliation(s)
- Hannah B Gordon
- Department of Human Genetics, University of Utah, Salt Lake City, UT 84112, USA
| | - Sarah Lusk
- Department of Human Genetics, University of Utah, Salt Lake City, UT 84112, USA
| | - Keith R Carney
- Department of Human Genetics, University of Utah, Salt Lake City, UT 84112, USA
| | - Emily O Wirick
- Department of Human Genetics, University of Utah, Salt Lake City, UT 84112, USA
| | | | - Kristen M Kwan
- Department of Human Genetics, University of Utah, Salt Lake City, UT 84112, USA
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22
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Slavotinek A. Genetics of anophthalmia and microphthalmia. Part 2: Syndromes associated with anophthalmia-microphthalmia. Hum Genet 2018; 138:831-846. [PMID: 30374660 DOI: 10.1007/s00439-018-1949-1] [Citation(s) in RCA: 38] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/10/2018] [Accepted: 10/20/2018] [Indexed: 12/12/2022]
Abstract
As new genes for A/M are identified in the genomic era, the number of syndromes associated with A/M has greatly expanded. In this review, we provide a brief synopsis of the clinical presentation and molecular genetic etiology of previously characterized pathways involved in A/M, including the Sex-determining region Y-box 2 (SOX2), Orthodenticle Homeobox 2 (OTX2) and Paired box protein-6 (PAX6) genes, and the Stimulated by retinoic acid gene 6 homolog (STRA6), Aldehyde Dehydrogenase 1 Family Member A3 (ALDH1A3), and RA Receptor Beta (RARβ) genes that are involved in retinoic acid synthesis. Less common genetic causes of A/M, including genes involved in BMP signaling [Bone Morphogenetic Protein 4 (BMP4), Bone Morphogenetic Protein 7 (BMP7) and SPARC-related modular calcium-binding protein 1 (SMOC1)], genes involved in the mitochondrial respiratory chain complex [Holocytochrome c-type synthase (HCCS), Cytochrome C Oxidase Subunit 7B (COX7B), and NADH:Ubiquinone Oxidoreductase subunit B11 (NDUFB11)], the BCL-6 corepressor gene (BCOR), Yes-Associated Protein 1 (YAP1) and Transcription Factor AP-2 Alpha (TFAP2α), are more briefly discussed. We also review several recently described genes and pathways associated with A/M, including Smoothened (SMO) that is involved in Sonic hedgehog (SHH) signaling, Structural maintenance of chromosomes flexible hinge domain containing 1 (SMCHD1) and Solute carrier family 25 member 24 (SLC25A24), emphasizing phenotype-genotype correlations and shared pathways where relevant.
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Affiliation(s)
- Anne Slavotinek
- Division of Genetics, Department of Pediatrics, University of California, San Francisco Room RH384C, 1550 4th St, San Francisco, CA, 94143-2711, USA.
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23
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Tanahashi H, Suzuki T. Deletion of Lrp4 increases the incidence of microphthalmia. Biochem Biophys Res Commun 2018; 506:478-484. [PMID: 30352686 DOI: 10.1016/j.bbrc.2018.10.062] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/18/2018] [Accepted: 10/09/2018] [Indexed: 10/28/2022]
Abstract
Microphthalmia is a malformation that reduces the size of the ocular globe. The etiologies of this anomaly are various, but the genetic background appears to have a predominant influence on its development through mutations of genes controlling ocular developmental processes. LRP4 is a type I single transmembrane protein that is essential for the formation of neuromuscular junctions. We created and experimented on homozygous Lrp4-deficient mice and found the microphthalmia phenotype in their eyes. The loss of Lrp4 resulted in an elevated incidence of microphthalmia and affected the mRNA expression of the members of bone morphogenetic protein, fibroblast growth factor, Sonic hedgehog, and WNT signaling pathways and of several pathogenic genes for microphthalmia. Moreover, the loss of Lrp4 enhanced the incidence of aberrant retinal folds, which appeared pleated and corrugated in the eyeball.
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Affiliation(s)
- Hiroshi Tanahashi
- Department of Neuroplasticity, School of Medicine, Shinshu University, 3-1-1 Asahi, Matsumoto, 390-8621, Japan.
| | - Tatsuo Suzuki
- Department of Molecular & Cellular Physiology, School of Medicine, Shinshu University, 3-1-1 Asahi, Matsumoto, 390-8621, Japan
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24
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Cavodeassi F, Creuzet S, Etchevers HC. The hedgehog pathway and ocular developmental anomalies. Hum Genet 2018; 138:917-936. [PMID: 30073412 PMCID: PMC6710239 DOI: 10.1007/s00439-018-1918-8] [Citation(s) in RCA: 37] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/16/2018] [Accepted: 07/24/2018] [Indexed: 12/18/2022]
Abstract
Mutations in effectors of the hedgehog signaling pathway are responsible for a wide variety of ocular developmental anomalies. These range from massive malformations of the brain and ocular primordia, not always compatible with postnatal life, to subtle but damaging functional effects on specific eye components. This review will concentrate on the effects and effectors of the major vertebrate hedgehog ligand for eye and brain formation, Sonic hedgehog (SHH), in tissues that constitute the eye directly and also in those tissues that exert indirect influence on eye formation. After a brief overview of human eye development, the many roles of the SHH signaling pathway during both early and later morphogenetic processes in the brain and then eye and periocular primordia will be evoked. Some of the unique molecular biology of this pathway in vertebrates, particularly ciliary signal transduction, will also be broached within this developmental cellular context.
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Affiliation(s)
- Florencia Cavodeassi
- Institute for Medical and Biomedical Education, St. George´s University of London, Cranmer Terrace, London, SW17 0RE, UK
| | - Sophie Creuzet
- Institut des Neurosciences Paris-Saclay (Neuro-PSI), UMR 9197, CNRS, Université Paris-Sud, 1 Avenue de la Terrasse, 91198, Gif-sur-Yvette Cedex, France
| | - Heather C Etchevers
- Aix-Marseille Univ, Marseille Medical Genetics (MMG), INSERM, Faculté de Médecine, 27 boulevard Jean Moulin, 13005, Marseille, France.
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25
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Bovolenta P, Martinez-Morales JR. Genetics of congenital eye malformations: insights from chick experimental embryology. Hum Genet 2018; 138:1001-1006. [PMID: 29980841 DOI: 10.1007/s00439-018-1900-5] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/10/2018] [Accepted: 06/26/2018] [Indexed: 12/27/2022]
Abstract
Embryological manipulations in chick embryos have been pivotal in our understanding of many aspects of vertebrate eye formation. This research was particularly important in uncovering the role of tissue interactions as drivers of eye morphogenesis and to dissect the function of critical genes. Here, we have highlighted a few of these past experiments to endorse their value in searching for hitherto unknown causes of rare congenital eye anomalies, such as microphthalmia, anophthalmia and coloboma. We have also highlighted a number of similarities between the chicken and human eye, which might be exploited to address other eye pathologies, including degenerative ocular diseases.
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Affiliation(s)
- Paola Bovolenta
- Centro de Biología Molecular "Severo Ochoa," (CSIC/UAM), 28049, Madrid, Spain.
- CIBERER, ISCIII, 28049, Madrid, Spain.
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26
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Elliott KH, Millington G, Brugmann SA. A novel role for cilia-dependent sonic hedgehog signaling during submandibular gland development. Dev Dyn 2018. [PMID: 29532549 DOI: 10.1002/dvdy.24627] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022] Open
Abstract
BACKGROUND Submandibular glands (SMGs) are specialized epithelial structures which generate saliva necessary for mastication and digestion. Loss of SMGs can lead to inflammation, oral lesions, fungal infections, problems with chewing/swallowing, and tooth decay. Understanding the development of the SMG is important for developing therapeutic options for patients with impaired SMG function. Recent studies have suggested Sonic hedgehog (Shh) signaling in the epithelium plays an integral role in SMG development; however, the mechanism by which Shh influences gland development remains nebulous. RESULTS Using the Kif3af/f ;Wnt1-Cre ciliopathic mouse model to prevent Shh signal transduction by means of the loss of primary cilia in neural crest cells, we report that mesenchymal Shh activity is necessary for gland development. Furthermore, using a variety of murine transgenic lines with aberrant mesenchymal Shh signal transduction, we determine that loss of Shh activity, by means of loss of the Gli activator, rather than gain of Gli repressor, is sufficient to cause the SMG aplasia. Finally, we determine that loss of the SMG correlates with reduced Neuregulin1 (Nrg1) expression and lack of innervation of the SMG epithelium. CONCLUSIONS Together, these data suggest a novel mechanistic role for mesenchymal Shh signaling during SMG development. Developmental Dynamics 247:818-831, 2018. © 2018 Wiley Periodicals, Inc.
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Affiliation(s)
- Kelsey H Elliott
- Division of Plastic Surgery, Department of Surgery, Cincinnati Children's Hospital Medical Center, Cincinnati, Ohio.,Division of Developmental Biology, Department of Pediatrics, Cincinnati Children's Hospital Medical Center, Cincinnati, Ohio
| | - Grethel Millington
- Division of Plastic Surgery, Department of Surgery, Cincinnati Children's Hospital Medical Center, Cincinnati, Ohio.,Division of Developmental Biology, Department of Pediatrics, Cincinnati Children's Hospital Medical Center, Cincinnati, Ohio
| | - Samantha A Brugmann
- Division of Plastic Surgery, Department of Surgery, Cincinnati Children's Hospital Medical Center, Cincinnati, Ohio.,Division of Developmental Biology, Department of Pediatrics, Cincinnati Children's Hospital Medical Center, Cincinnati, Ohio
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27
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Bruel AL, Thevenon J, Huet F, Jean-Marcais N, Odent S, Dubourg C, Lehalle D, Tran Mau-Them F, Philippe C, Moutton S, Houcinat N, Gay S, Guibaud L, Duffourd Y, Rivière JB, Faivre L, Thauvin-Robinet C. Unexpected diagnosis of a SHH nonsense variant causing a variable phenotype ranging from familial coloboma and Intellectual disability to isolated microcephaly. Clin Genet 2018; 94:182-184. [PMID: 29498412 DOI: 10.1111/cge.13211] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/03/2017] [Revised: 01/09/2018] [Accepted: 01/11/2018] [Indexed: 12/15/2022]
Affiliation(s)
- A-L Bruel
- Fédération Hospitalo-Universitaire Médecine Translationnelle et Anomalies du Développement (TRANSLAD), CHU, Dijon, France.,UMR 1231 GAD, Génétique des Anomalies du Développement, UBFC, Dijon, France
| | - J Thevenon
- Fédération Hospitalo-Universitaire Médecine Translationnelle et Anomalies du Développement (TRANSLAD), CHU, Dijon, France.,UMR 1231 GAD, Génétique des Anomalies du Développement, UBFC, Dijon, France.,Centre de Génétique et Centre de Référence Anomalies du Développement et Syndromes Malformatifs de l'Inter-région Est, CHU, Dijon, France
| | - F Huet
- Service Pédiatrie, CHU, Dijon, France
| | - N Jean-Marcais
- Fédération Hospitalo-Universitaire Médecine Translationnelle et Anomalies du Développement (TRANSLAD), CHU, Dijon, France.,UMR 1231 GAD, Génétique des Anomalies du Développement, UBFC, Dijon, France.,Centre de Génétique et Centre de Référence Anomalies du Développement et Syndromes Malformatifs de l'Inter-région Est, CHU, Dijon, France
| | - S Odent
- Service Génétique Clinique, CHU, Rennes, France.,CNRS UMR6290, IGDR, Université de Rennes 1, Rennes, France
| | - C Dubourg
- CNRS UMR6290, IGDR, Université de Rennes 1, Rennes, France.,Service Génétique Moléculaire et Génomique, CHU, Rennes, France
| | - D Lehalle
- Fédération Hospitalo-Universitaire Médecine Translationnelle et Anomalies du Développement (TRANSLAD), CHU, Dijon, France.,UMR 1231 GAD, Génétique des Anomalies du Développement, UBFC, Dijon, France.,Centre de Génétique et Centre de Référence Anomalies du Développement et Syndromes Malformatifs de l'Inter-région Est, CHU, Dijon, France
| | - F Tran Mau-Them
- Fédération Hospitalo-Universitaire Médecine Translationnelle et Anomalies du Développement (TRANSLAD), CHU, Dijon, France.,UMR 1231 GAD, Génétique des Anomalies du Développement, UBFC, Dijon, France
| | - C Philippe
- Fédération Hospitalo-Universitaire Médecine Translationnelle et Anomalies du Développement (TRANSLAD), CHU, Dijon, France.,UMR 1231 GAD, Génétique des Anomalies du Développement, UBFC, Dijon, France
| | - S Moutton
- Fédération Hospitalo-Universitaire Médecine Translationnelle et Anomalies du Développement (TRANSLAD), CHU, Dijon, France.,UMR 1231 GAD, Génétique des Anomalies du Développement, UBFC, Dijon, France.,Centre de Génétique et Centre de Référence Anomalies du Développement et Syndromes Malformatifs de l'Inter-région Est, CHU, Dijon, France
| | - N Houcinat
- Fédération Hospitalo-Universitaire Médecine Translationnelle et Anomalies du Développement (TRANSLAD), CHU, Dijon, France.,UMR 1231 GAD, Génétique des Anomalies du Développement, UBFC, Dijon, France.,Centre de Génétique et Centre de Référence Anomalies du Développement et Syndromes Malformatifs de l'Inter-région Est, CHU, Dijon, France
| | - S Gay
- Service Pédiatrie, CH, Chalon-sur Saône, France
| | - L Guibaud
- Service Radiologie, Hospices Civils de Lyon, Lyon, France
| | - Y Duffourd
- Fédération Hospitalo-Universitaire Médecine Translationnelle et Anomalies du Développement (TRANSLAD), CHU, Dijon, France.,UMR 1231 GAD, Génétique des Anomalies du Développement, UBFC, Dijon, France
| | - J-B Rivière
- Fédération Hospitalo-Universitaire Médecine Translationnelle et Anomalies du Développement (TRANSLAD), CHU, Dijon, France.,UMR 1231 GAD, Génétique des Anomalies du Développement, UBFC, Dijon, France
| | - L Faivre
- Fédération Hospitalo-Universitaire Médecine Translationnelle et Anomalies du Développement (TRANSLAD), CHU, Dijon, France.,UMR 1231 GAD, Génétique des Anomalies du Développement, UBFC, Dijon, France.,Centre de Génétique et Centre de Référence Anomalies du Développement et Syndromes Malformatifs de l'Inter-région Est, CHU, Dijon, France
| | - C Thauvin-Robinet
- Fédération Hospitalo-Universitaire Médecine Translationnelle et Anomalies du Développement (TRANSLAD), CHU, Dijon, France.,UMR 1231 GAD, Génétique des Anomalies du Développement, UBFC, Dijon, France.,Centre de Génétique et Centre de Référence Anomalies du Développement et Syndromes Malformatifs de l'Inter-région Est, CHU, Dijon, France
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Wheway G, Nazlamova L, Hancock JT. Signaling through the Primary Cilium. Front Cell Dev Biol 2018; 6:8. [PMID: 29473038 PMCID: PMC5809511 DOI: 10.3389/fcell.2018.00008] [Citation(s) in RCA: 305] [Impact Index Per Article: 50.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2017] [Accepted: 01/23/2018] [Indexed: 12/13/2022] Open
Abstract
The presence of single, non-motile “primary” cilia on the surface of epithelial cells has been well described since the 1960s. However, for decades these organelles were believed to be vestigial, with no remaining function, having lost their motility. It wasn't until 2003, with the discovery that proteins responsible for transport along the primary cilium are essential for hedgehog signaling in mice, that the fundamental importance of primary cilia in signal transduction was realized. Little more than a decade later, it is now clear that the vast majority of signaling pathways in vertebrates function through the primary cilium. This has led to the adoption of the term “the cells's antenna” as a description for the primary cilium. Primary cilia are particularly important during development, playing fundamental roles in embryonic patterning and organogenesis, with a suite of inherited developmental disorders known as the “ciliopathies” resulting from mutations in genes encoding cilia proteins. This review summarizes our current understanding of the role of these fascinating organelles in a wide range of signaling pathways.
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Affiliation(s)
- Gabrielle Wheway
- Department of Applied Science, Faculty of Health and Applied Sciences, Centre for Research in Biosciences, University of the West of England, Bristol, United Kingdom
| | - Liliya Nazlamova
- Department of Applied Science, Faculty of Health and Applied Sciences, Centre for Research in Biosciences, University of the West of England, Bristol, United Kingdom
| | - John T Hancock
- Department of Applied Science, Faculty of Health and Applied Sciences, Centre for Research in Biosciences, University of the West of England, Bristol, United Kingdom
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29
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Genes and pathways in optic fissure closure. Semin Cell Dev Biol 2017; 91:55-65. [PMID: 29198497 DOI: 10.1016/j.semcdb.2017.10.010] [Citation(s) in RCA: 34] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/22/2017] [Revised: 08/29/2017] [Accepted: 10/10/2017] [Indexed: 12/22/2022]
Abstract
Embryonic development of the vertebrate eye begins with the formation of an optic vesicle which folds inwards to form a double-layered optic cup with a fissure on the ventral surface, known as the optic fissure. Closure of the optic fissure is essential for subsequent growth and development of the eye. A defect in this process can leave a gap in the iris, retina or optic nerve, known as a coloboma, which can lead to severe visual impairment. This review brings together current information about genes and pathways regulating fissure closure from human coloboma patients and animal models. It focuses especially on current understanding of the morphological changes and processes of epithelial remodelling occurring at the fissure margins.
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30
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Sedykh I, Yoon B, Roberson L, Moskvin O, Dewey CN, Grinblat Y. Zebrafish zic2 controls formation of periocular neural crest and choroid fissure morphogenesis. Dev Biol 2017; 429:92-104. [PMID: 28689736 DOI: 10.1016/j.ydbio.2017.07.003] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/14/2017] [Revised: 05/30/2017] [Accepted: 07/06/2017] [Indexed: 12/31/2022]
Abstract
The vertebrate retina develops in close proximity to the forebrain and neural crest-derived cartilages of the face and jaw. Coloboma, a congenital eye malformation, is associated with aberrant forebrain development (holoprosencephaly) and with craniofacial defects (frontonasal dysplasia) in humans, suggesting a critical role for cross-lineage interactions during retinal morphogenesis. ZIC2, a zinc-finger transcription factor, is linked to human holoprosencephaly. We have previously used morpholino assays to show zebrafish zic2 functions in the developing forebrain, retina and craniofacial cartilage. We now report that zebrafish with genetic lesions in zebrafish zic2 orthologs, zic2a and zic2b, develop with retinal coloboma and craniofacial anomalies. We demonstrate a requirement for zic2 in restricting pax2a expression and show evidence that zic2 function limits Hh signaling. RNA-seq transcriptome analysis identified an early requirement for zic2 in periocular neural crest as an activator of alx1, a transcription factor with essential roles in craniofacial and ocular morphogenesis in human and zebrafish. Collectively, these data establish zic2 mutant zebrafish as a powerful new genetic model for in-depth dissection of cell interactions and genetic controls during craniofacial complex development.
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Affiliation(s)
- Irina Sedykh
- Department of Integrative Biology, University of Wisconsin, Madison, WI 53706, USA; Department of Neuroscience, University of Wisconsin, Madison, WI 53706, USA
| | - Baul Yoon
- Department of Integrative Biology, University of Wisconsin, Madison, WI 53706, USA; Department of Neuroscience, University of Wisconsin, Madison, WI 53706, USA; Genetics Ph. D. Training Program, University of Wisconsin, Madison, WI 53706, USA
| | - Laura Roberson
- Department of Integrative Biology, University of Wisconsin, Madison, WI 53706, USA; Department of Neuroscience, University of Wisconsin, Madison, WI 53706, USA
| | - Oleg Moskvin
- Primate Research Center, University of Wisconsin-Madison, Madison, WI 53706, USA
| | - Colin N Dewey
- Department of Biostatistics and Medical Informatics, University of Wisconsin-Madison, Madison, WI 53706, USA
| | - Yevgenya Grinblat
- Department of Integrative Biology, University of Wisconsin, Madison, WI 53706, USA; Department of Neuroscience, University of Wisconsin, Madison, WI 53706, USA; McPherson Eye Research Institute, University of Wisconsin, Madison, WI, 53706, USA.
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31
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Williams AL, Eason J, Chawla B, Bohnsack BL. Cyp1b1 Regulates Ocular Fissure Closure Through a Retinoic Acid-Independent Pathway. Invest Ophthalmol Vis Sci 2017; 58:1084-1097. [PMID: 28192799 PMCID: PMC5308778 DOI: 10.1167/iovs.16-20235] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022] Open
Abstract
Purpose Mutations in the CYP1B1 gene are the most commonly identified genetic causes of primary infantile-onset glaucoma. Despite this disease association, the role of CYP1B1 in eye development and its in vivo substrate remain unknown. In the present study, we used zebrafish to elucidate the mechanism by which cyp1b1 regulates eye development. Methods Zebrafish eye and neural crest development were analyzed using live imaging of transgenic zebrafish embryos, in situ hybridization, immunostaining, TUNEL assay, and methylacrylate sections. Cyp1b1 and retinoic acid (RA) levels were genetically (morpholino oligonucleotide antisense and mRNA) and pharmacologically manipulated to examine gene function. Results Using zebrafish, we observed that cyp1b1 was expressed in a specific spatiotemporal pattern in the ocular fissures of the developing zebrafish retina and regulated fissure patency. Decreased Cyp1b1 resulted in the premature breakdown of laminin in the ventral fissure and altered subsequent neural crest migration into the anterior segment. In contrast, cyp1b1 overexpression inhibited cell survival in the ventral ocular fissure and prevented fissure closure via an RA-independent pathway. Cyp1b1 overexpression also inhibited the ocular expression of vsx2, pax6a, and pax6b and increased the extraocular expression of shha. Importantly, embryos injected with human wild-type but not mutant CYP1B1 mRNA also showed colobomas, demonstrating the evolutionary and functional conservation of gene function between species. Conclusions Cyp1b1 regulation of ocular fissure closure indirectly affects neural crest migration and development through an RA-independent pathway. These studies provide insight into the role of Cyp1b1 in eye development and further elucidate the pathogenesis of primary infantile-onset glaucoma.
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Affiliation(s)
- Antionette L Williams
- Department of Ophthalmology and Visual Sciences, Kellogg Eye Center, University of Michigan, Ann Arbor, Michigan, United States
| | - Jessica Eason
- Department of Ophthalmology and Visual Sciences, Kellogg Eye Center, University of Michigan, Ann Arbor, Michigan, United States
| | - Bahaar Chawla
- Department of Ophthalmology and Visual Sciences, Kellogg Eye Center, University of Michigan, Ann Arbor, Michigan, United States
| | - Brenda L Bohnsack
- Department of Ophthalmology and Visual Sciences, Kellogg Eye Center, University of Michigan, Ann Arbor, Michigan, United States
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32
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Jackson CC, Lefèvre-Utile A, Guimier A, Malan V, Bruneau J, Gessain A, Cassar O, Amiel J, Cobat A, Rattina V, Abel L, Casanova JL, Blanche S. Kaposi sarcoma, oral malformations, mitral dysplasia, and scoliosis associated with 7q34-q36.3 heterozygous terminal deletion. Am J Med Genet A 2017; 173:1858-1865. [PMID: 28488400 DOI: 10.1002/ajmg.a.38275] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2016] [Accepted: 04/04/2017] [Indexed: 12/13/2022]
Abstract
Chromosome 7 germline macrodeletions have been implicated in human congenital malformations and developmental delays. We herein report a novel heterozygous macrodeletion of 7q34-q36.3 in a 16-year-old girl originally from West Indies. Similar to previously reported cases of germline chromosome 7q terminal deletions, our patient has dental malposition, and developmental (growth and intellectual) delay. Novel phenotypic features include endemic Kaposi sarcoma (KS), furrowed tongue, thoracolumbar scoliosis, and mild mitral valve dysplasia. The occurrence of human herpes virus 8-driven KS, in a child otherwise normally resistant to other infectious agents and without any other tumoral lesion, points to a very selective immunodeficiency. While defects in organogenesis have been described with such macrodeletions, this is the first report of immunodeficiency and cancer predisposition.
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Affiliation(s)
- Carolyn C Jackson
- St. Giles Laboratory of Human Genetics of Infectious Diseases, Rockefeller Branch, The Rockefeller University, New York, New York.,Department of Pediatrics, The Memorial Sloan Kettering Cancer Center, New York, New York.,Division of Pediatric Hematology/Oncology, Weill Cornell Medical Center, New York, New York
| | - Alain Lefèvre-Utile
- Pediatric Immunology-Hematology-Rheumatology Unit, Necker-Enfants Malades Hospital, Paris, France
| | - Anne Guimier
- Department of Genetics, Necker-Enfants Malades Hospital, AP-HP, Paris, France
| | - Valérie Malan
- Department of Genetics, Necker-Enfants Malades Hospital, AP-HP, Paris, France
| | - Julie Bruneau
- Unit of Pathology, Necker-Enfants Malades Hospital, Paris, France
| | - Antoine Gessain
- Unit of Epidemiology and Physiopathology of Oncogenic Viruses, Pasteur Institute, Paris, France
| | - Olivier Cassar
- Unit of Epidemiology and Physiopathology of Oncogenic Viruses, Pasteur Institute, Paris, France
| | - Jeanne Amiel
- Department of Genetics, Necker-Enfants Malades Hospital, AP-HP, Paris, France
| | - Aurélie Cobat
- Laboratory of Human Genetics of Infectious Diseases, Necker Branch, Necker-Enfants Malades Hospital, INSERM, Paris, France.,Paris Descartes University, Imagine Institute, Paris, France
| | - Vimel Rattina
- Laboratory of Human Genetics of Infectious Diseases, Necker Branch, Necker-Enfants Malades Hospital, INSERM, Paris, France.,Paris Descartes University, Imagine Institute, Paris, France
| | - Laurent Abel
- St. Giles Laboratory of Human Genetics of Infectious Diseases, Rockefeller Branch, The Rockefeller University, New York, New York.,Laboratory of Human Genetics of Infectious Diseases, Necker Branch, Necker-Enfants Malades Hospital, INSERM, Paris, France.,Paris Descartes University, Imagine Institute, Paris, France
| | - Jean-Laurent Casanova
- St. Giles Laboratory of Human Genetics of Infectious Diseases, Rockefeller Branch, The Rockefeller University, New York, New York.,Pediatric Immunology-Hematology-Rheumatology Unit, Necker-Enfants Malades Hospital, Paris, France.,Laboratory of Human Genetics of Infectious Diseases, Necker Branch, Necker-Enfants Malades Hospital, INSERM, Paris, France.,Paris Descartes University, Imagine Institute, Paris, France.,Howard Hughes Medical Institute, New York, New York
| | - Stéphane Blanche
- Pediatric Immunology-Hematology-Rheumatology Unit, Necker-Enfants Malades Hospital, Paris, France
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33
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Clinical utility gene card for: Non-Syndromic Microphthalmia Including Next-Generation Sequencing-Based Approaches. Eur J Hum Genet 2017; 25:ejhg2016201. [PMID: 28098148 DOI: 10.1038/ejhg.2016.201] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/09/2016] [Revised: 11/28/2016] [Accepted: 12/14/2016] [Indexed: 11/08/2022] Open
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34
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James A, Lee C, Williams AM, Angileri K, Lathrop KL, Gross JM. The hyaloid vasculature facilitates basement membrane breakdown during choroid fissure closure in the zebrafish eye. Dev Biol 2016; 419:262-272. [PMID: 27634568 DOI: 10.1016/j.ydbio.2016.09.008] [Citation(s) in RCA: 38] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/05/2016] [Revised: 09/09/2016] [Accepted: 09/09/2016] [Indexed: 12/22/2022]
Abstract
A critical aspect of vertebrate eye development is closure of the choroid fissure (CF). Defects in CF closure result in colobomas, which are a significant cause of childhood blindness worldwide. Despite the growing number of mutated loci associated with colobomas, we have a limited understanding of the cell biological underpinnings of CF closure. Here, we utilize the zebrafish embryo to identify key phases of CF closure and regulators of the process. Utilizing Laminin-111 as a marker for the basement membrane (BM) lining the CF, we determine the spatial and temporal patterns of BM breakdown in the CF, a prerequisite for CF closure. Similarly, utilizing a combination of in vivo time-lapse imaging, β-catenin immunohistochemistry and F-actin staining, we determine that tissue fusion, which serves to close the fissure, follows BM breakdown closely. Periocular mesenchyme (POM)-derived endothelial cells, which migrate through the CF to give rise to the hyaloid vasculature, possess distinct actin foci that correlate with regions of BM breakdown. Disruption of talin1, which encodes a regulator of the actin cytoskeleton, results in colobomas and these correlate with structural defects in the hyaloid vasculature and defects in BM breakdown. cloche mutants, which entirely lack a hyaloid vasculature, also possess defects in BM breakdown in the CF. Taken together, these data support a model in which the hyaloid vasculature and/or the POM-derived endothelial cells that give rise to the hyaloid vasculature contribute to BM breakdown during CF closure.
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Affiliation(s)
- Andrea James
- Department of Molecular Biosciences, Institute for Cellular and Molecular Biology, The University of Texas at Austin, Austin TX, 78712
- Department of Ophthalmology, Louis J. Fox Center for Vision Restoration, The University of Pittsburgh School of Medicine, Pittsburgh, PA 15213
| | - Chanjae Lee
- Department of Molecular Biosciences, Institute for Cellular and Molecular Biology, The University of Texas at Austin, Austin TX, 78712
| | - Andre M Williams
- Department of Molecular Biosciences, Institute for Cellular and Molecular Biology, The University of Texas at Austin, Austin TX, 78712
| | - Krista Angileri
- Department of Molecular Biosciences, Institute for Cellular and Molecular Biology, The University of Texas at Austin, Austin TX, 78712
- Department of Ophthalmology, Louis J. Fox Center for Vision Restoration, The University of Pittsburgh School of Medicine, Pittsburgh, PA 15213
| | - Kira L Lathrop
- Department of Ophthalmology, Louis J. Fox Center for Vision Restoration, The University of Pittsburgh School of Medicine, Pittsburgh, PA 15213
- Department of Bioengineering, University of Pittsburgh Swanson School of Engineering, Pittsburgh, PA 15213
| | - Jeffrey M Gross
- Department of Molecular Biosciences, Institute for Cellular and Molecular Biology, The University of Texas at Austin, Austin TX, 78712
- Department of Ophthalmology, Louis J. Fox Center for Vision Restoration, The University of Pittsburgh School of Medicine, Pittsburgh, PA 15213
- Department of Developmental Biology, The University of Pittsburgh School of Medicine, Pittsburgh, PA 15213
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35
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Dworkin S, Boglev Y, Owens H, Goldie SJ. The Role of Sonic Hedgehog in Craniofacial Patterning, Morphogenesis and Cranial Neural Crest Survival. J Dev Biol 2016; 4:jdb4030024. [PMID: 29615588 PMCID: PMC5831778 DOI: 10.3390/jdb4030024] [Citation(s) in RCA: 40] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/07/2016] [Revised: 07/20/2016] [Accepted: 07/26/2016] [Indexed: 01/01/2023] Open
Abstract
Craniofacial defects (CFD) are a significant healthcare problem worldwide. Understanding both the morphogenetic movements which underpin normal facial development, as well as the molecular factors which regulate these processes, forms the cornerstone of future diagnostic, and ultimately, preventative therapies. The soluble morphogen Sonic hedgehog (Shh), a vertebrate orthologue of Drosophila hedgehog, is a key signalling factor in the regulation of craniofacial skeleton development in vertebrates, operating within numerous tissue types in the craniofacial primordia to spatiotemporally regulate the formation of the face and jaws. This review will provide an overview of normal craniofacial skeleton development, and focus specifically on the known roles of Shh in regulating the development and progression of the first pharyngeal arch, which in turn gives rise to both the upper jaw (maxilla) and lower jaw (mandible).
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Affiliation(s)
- Sebastian Dworkin
- Department of Medicine, Monash University Central Clinical School, Prahran, Victoria 3004, Australia.
- Department of Physiology, Anatomy and Microbiology, La Trobe University, Melbourne, Victoria 3086, Australia.
| | - Yeliz Boglev
- Department of Biochemistry and Genetics, La Trobe Institute for Molecular Science, La Trobe University, Melbourne, Victoria 3086, Australia.
| | - Harley Owens
- Department of Medicine, Monash University Central Clinical School, Prahran, Victoria 3004, Australia.
| | - Stephen J Goldie
- Department of Medicine, Monash University Central Clinical School, Prahran, Victoria 3004, Australia.
- Department of Surgery, Monash University Central Clinical School, Prahran, Victoria 3004, Australia.
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36
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Abstract
Kabuki syndrome is a rare genetic malformation syndrome that is characterized by distinct facies, structural defects and intellectual disability. Kabuki syndrome may be caused by mutations in one of two histone methyltransferase genes: KMT2D and KDM6A. We describe a male child of nonconsanguineous Irish parents presenting with multiple malformations, including bilateral extreme microphthalmia; cleft palate; congenital diaphragmatic hernia; duplex kidney; as well as facial features of Kabuki syndrome, including interrupted eyebrows and lower lid ectropion. A de-novo germline mutation in KMT2D was identified. Whole-exome sequencing failed to reveal mutations in any of the known microphthalmia/anopthalmia genes. We also identified four other patients with Kabuki syndrome and microphthalmia. We postulate that Kabuki syndrome may produce this type of ocular phenotype as a result of extensive interaction between KMT2D, WAR complex proteins and PAXIP1. Children presenting with microphthalmia/anophthalmia should be examined closely for other signs of Kabuki syndrome, especially at an age where the facial gestalt might be less readily appreciable.
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37
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Prabhudesai S, Bensabeur FZ, Abdullah R, Basak I, Baez S, Alves G, Holtzman NG, Larsen JP, Møller SG. LRRK2 knockdown in zebrafish causes developmental defects, neuronal loss, and synuclein aggregation. J Neurosci Res 2016; 94:717-35. [PMID: 27265751 DOI: 10.1002/jnr.23754] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/29/2015] [Revised: 03/31/2016] [Accepted: 03/31/2016] [Indexed: 12/30/2022]
Abstract
Although mutations in the leucine-rich repeat kinase 2 (LRRK2) gene are the most common cause of genetic Parkinson's disease, their function is largely unknown. LRRK2 is pleiotropic in nature, shown to be involved in neurodegeneration and in more peripheral processes, including kidney functions, in rats and mice. Recent studies in zebrafish have shown conflicting evidence that removal of the LRRK2 WD40 domain may or may not affect dopaminergic neurons and/or locomotion. This study shows that ∼50% LRRK2 knockdown in zebrafish causes not only neuronal loss but also developmental perturbations such as axis curvature defects, ocular abnormalities, and edema in the eyes, lens, and otic vesicles. We further show that LRRK2 knockdown results in significant neuronal loss, including a reduction of dopaminergic neurons. Immunofluorescence demonstrates that endogenous LRRK2 is expressed in the lens, brain, heart, spinal cord, and kidney (pronephros), which mirror the LRRK2 morphant phenotypes observed. LRRK2 knockdown results further in the concomitant upregulation of β-synuclein, PARK13, and SOD1 and causes β-synuclein aggregation in the diencephalon, midbrain, hindbrain, and postoptic commissure. LRRK2 knockdown causes mislocalization of the Na(+) /K(+) ATPase protein in the pronephric ducts, suggesting that the edema might be linked to renal malfunction and that LRRK2 might be associated with pronephric duct epithelial cell differentiation. Combined, our study shows that LRRK2 has multifaceted roles in zebrafish and that zebrafish represent a complementary model to further our understanding of this central protein. © 2016 Wiley Periodicals, Inc.
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Affiliation(s)
| | | | - Rashed Abdullah
- Department of Biological Sciences, St. John's University, Queens, New York
| | - Indranil Basak
- Department of Biological Sciences, St. John's University, Queens, New York
| | - Solange Baez
- Department of Biological Sciences, St. John's University, Queens, New York
| | - Guido Alves
- The Norwegian Centre for Movement Disorders, Stavanger University Hospital, Stavanger, Norway
| | - Nathalia G Holtzman
- Department of Biology, Queens College and The Graduate Center, CUNY, Queens, New York
| | - Jan Petter Larsen
- The Norwegian Centre for Movement Disorders, Stavanger University Hospital, Stavanger, Norway
| | - Simon Geir Møller
- Department of Biological Sciences, St. John's University, Queens, New York.,The Norwegian Centre for Movement Disorders, Stavanger University Hospital, Stavanger, Norway
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38
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Liu C, Widen SA, Williamson KA, Ratnapriya R, Gerth-Kahlert C, Rainger J, Alur RP, Strachan E, Manjunath SH, Balakrishnan A, Floyd JA, Li T, Waskiewicz A, Brooks BP, Lehmann OJ, FitzPatrick DR, Swaroop A. A secreted WNT-ligand-binding domain of FZD5 generated by a frameshift mutation causes autosomal dominant coloboma. Hum Mol Genet 2016; 25:1382-91. [PMID: 26908622 DOI: 10.1093/hmg/ddw020] [Citation(s) in RCA: 34] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/29/2015] [Accepted: 01/18/2016] [Indexed: 12/15/2022] Open
Abstract
Ocular coloboma is a common eye malformation resulting from incomplete fusion of the optic fissure during development. Coloboma is often associated with microphthalmia and/or contralateral anophthalmia. Coloboma shows extensive locus heterogeneity associated with causative mutations identified in genes encoding developmental transcription factors or components of signaling pathways. We report an ultra-rare, heterozygous frameshift mutation in FZD5 (p.Ala219Glufs*49) that was identified independently in two branches of a large family with autosomal dominant non-syndromic coloboma. FZD5 has a single-coding exon and consequently a transcript with this frameshift variant is not a canonical substrate for nonsense-mediated decay. FZD5 encodes a transmembrane receptor with a conserved extracellular cysteine rich domain for ligand binding. The frameshift mutation results in the production of a truncated protein, which retains the Wingless-type MMTV integration site family member-ligand-binding domain, but lacks the transmembrane domain. The truncated protein was secreted from cells, and behaved as a dominant-negative FZD5 receptor, antagonizing both canonical and non-canonical WNT signaling. Expression of the resultant mutant protein caused coloboma and microphthalmia in zebrafish, and disruption of the apical junction of the retinal neural epithelium in mouse, mimicking the phenotype of Fz5/Fz8 compound conditional knockout mutants. Our studies have revealed a conserved role of Wnt-Frizzled (FZD) signaling in ocular development and directly implicate WNT-FZD signaling both in normal closure of the human optic fissure and pathogenesis of coloboma.
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Affiliation(s)
- Chunqiao Liu
- Neurobiology-Neurodegeneration and Repair Laboratory, National Eye Institute, National Institutes of Health, 6 Center Drive, Bethesda, MD 20892, USA, State Key Laboratory of Ophthalmology, Zhongshan Ophthalmic Center, Sun Yat-sen University, Guangzhou 510060, China
| | - Sonya A Widen
- Department of Biological Sciences, University of Alberta, Edmonton, AB, Canada T6G 2E9
| | - Kathleen A Williamson
- MRC Human Genetics Unit, Institute of Genetics and Molecular Medicine, University of Edinburgh, Edinburgh EH4 2XU, UK
| | - Rinki Ratnapriya
- Neurobiology-Neurodegeneration and Repair Laboratory, National Eye Institute, National Institutes of Health, 6 Center Drive, Bethesda, MD 20892, USA
| | - Christina Gerth-Kahlert
- Department of Ophthalmology, University Hospital Zurich, Frauenklinikstrasse 24, Zurich 8091, Switzerland
| | - Joe Rainger
- MRC Human Genetics Unit, Institute of Genetics and Molecular Medicine, University of Edinburgh, Edinburgh EH4 2XU, UK
| | - Ramakrishna P Alur
- Unit on Pediatric, Developmental, and Genetic Eye Disease, National Eye Institute, 10 Center Drive, Bethesda, MD 20892, USA
| | - Erin Strachan
- Department of Ophthalmology and Visual Sciences, University of Alberta, Edmonton, AB, Canada T6G 2H7
| | - Souparnika H Manjunath
- Neurobiology-Neurodegeneration and Repair Laboratory, National Eye Institute, National Institutes of Health, 6 Center Drive, Bethesda, MD 20892, USA
| | - Archana Balakrishnan
- Neurobiology-Neurodegeneration and Repair Laboratory, National Eye Institute, National Institutes of Health, 6 Center Drive, Bethesda, MD 20892, USA
| | - James A Floyd
- Welcome Trust Sanger Institute, Hinxton, Cambridge CB10 1HH, UK and
| | | | - Tiansen Li
- Neurobiology-Neurodegeneration and Repair Laboratory, National Eye Institute, National Institutes of Health, 6 Center Drive, Bethesda, MD 20892, USA
| | - Andrew Waskiewicz
- Department of Biological Sciences, University of Alberta, Edmonton, AB, Canada T6G 2E9,
| | - Brian P Brooks
- Unit on Pediatric, Developmental, and Genetic Eye Disease, National Eye Institute, 10 Center Drive, Bethesda, MD 20892, USA
| | - Ordan J Lehmann
- Department of Ophthalmology and Visual Sciences, University of Alberta, Edmonton, AB, Canada T6G 2H7, Department of Medical Genetics, University of Alberta, Edmonton, AB, Canada T6G 2H7
| | - David R FitzPatrick
- MRC Human Genetics Unit, Institute of Genetics and Molecular Medicine, University of Edinburgh, Edinburgh EH4 2XU, UK,
| | - Anand Swaroop
- Neurobiology-Neurodegeneration and Repair Laboratory, National Eye Institute, National Institutes of Health, 6 Center Drive, Bethesda, MD 20892, USA,
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Reis LM, Semina EV. Conserved genetic pathways associated with microphthalmia, anophthalmia, and coloboma. ACTA ACUST UNITED AC 2015; 105:96-113. [PMID: 26046913 DOI: 10.1002/bdrc.21097] [Citation(s) in RCA: 50] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/01/2015] [Accepted: 05/13/2015] [Indexed: 12/19/2022]
Abstract
The human eye is a complex organ whose development requires extraordinary coordination of developmental processes. The conservation of ocular developmental steps in vertebrates suggests possible common genetic mechanisms. Genetic diseases involving the eye represent a leading cause of blindness in children and adults. During the last decades, there has been an exponential increase in genetic studies of ocular disorders. In this review, we summarize current success in identification of genes responsible for microphthalmia, anophthalmia, and coloboma (MAC) phenotypes, which are associated with early defects in embryonic eye development. Studies in animal models for the orthologous genes identified overlapping phenotypes for most factors, confirming the conservation of their function in vertebrate development. These animal models allow for further investigation of the mechanisms of MAC, integration of various identified genes into common developmental pathways and finally, provide an avenue for the development and testing of therapeutic interventions.
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Affiliation(s)
- Linda M Reis
- Department of Pediatrics and Children's Research Institute, Medical College of Wisconsin, Milwaukee, Wisconsin
| | - Elena V Semina
- Department of Pediatrics and Children's Research Institute, Medical College of Wisconsin, Milwaukee, Wisconsin.,Department of Ophthalmology, Medical College of Wisconsin, Milwaukee, Wisconsin.,Department of Cell Biology Neurobiology, and Anatomy, Medical College of Wisconsin, Milwaukee, Wisconsin
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40
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Deml B, Kariminejad A, Borujerdi RHR, Muheisen S, Reis LM, Semina EV. Mutations in MAB21L2 result in ocular Coloboma, microcornea and cataracts. PLoS Genet 2015; 11:e1005002. [PMID: 25719200 PMCID: PMC4342166 DOI: 10.1371/journal.pgen.1005002] [Citation(s) in RCA: 41] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/09/2014] [Accepted: 01/14/2015] [Indexed: 12/12/2022] Open
Abstract
Ocular coloboma results from abnormal embryonic development and is often associated with additional ocular and systemic features. Coloboma is a highly heterogeneous disorder with many cases remaining unexplained. Whole exome sequencing from two cousins affected with dominant coloboma with microcornea, cataracts, and skeletal dysplasia identified a novel heterozygous allele in MAB21L2, c.151 C>G, p.(Arg51Gly); the mutation was present in all five family members with the disease and appeared de novo in the first affected generation of the three-generational pedigree. MAB21L2 encodes a protein similar to C. elegans mab-21 cell fate-determining factor; the molecular function of MAB21L2 is largely unknown. To further evaluate the role of MAB21L2, zebrafish mutants carrying a p.(Gln48Serfs*5) frameshift truncation (mab21l2Q48Sfs*5) and a p.(Arg51_Phe52del) in-frame deletion (mab21l2R51_F52del) were developed with TALEN technology. Homozygous zebrafish embryos from both lines developed variable lens and coloboma phenotypes: mab21l2Q48Sfs*5 embryos demonstrated severe lens and retinal defects with complete lethality while mab21l2R51_F52del mutants displayed a milder lens phenotype and severe coloboma with a small number of fish surviving to adulthood. Protein studies showed decreased stability for the human p.(Arg51Gly) and zebrafish p.(Arg51_Phe52del) mutant proteins and predicted a complete loss-of-function for the zebrafish p.(Gln48Serfs*5) frameshift truncation. Additionally, in contrast to wild-type human MAB21L2 transcript, mutant p.(Arg51Gly) mRNA failed to efficiently rescue the ocular phenotype when injected into mab21l2Q48Sfs*5 embryos, suggesting this allele is functionally deficient. Histology, immunohistochemistry, and in situ hybridization experiments identified retinal invagination defects, an increase in cell death, abnormal proliferation patterns, and altered expression of several ocular markers in the mab21l2 mutants. These findings support the identification of MAB21L2 as a novel factor involved in human coloboma and highlight the power of genome editing manipulation in model organisms for analysis of the effects of whole exome variation in humans.
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Affiliation(s)
- Brett Deml
- Department of Pediatrics and Children’s Research Institute at the Medical College of Wisconsin and Children’s Hospital of Wisconsin, Milwaukee, Wisconsin, United States of America
- Department of Cell Biology, Neurobiology and Anatomy, Medical College of Wisconsin, Milwaukee, Wisconsin, United States of America
| | | | | | - Sanaa Muheisen
- Department of Pediatrics and Children’s Research Institute at the Medical College of Wisconsin and Children’s Hospital of Wisconsin, Milwaukee, Wisconsin, United States of America
| | - Linda M. Reis
- Department of Pediatrics and Children’s Research Institute at the Medical College of Wisconsin and Children’s Hospital of Wisconsin, Milwaukee, Wisconsin, United States of America
| | - Elena V. Semina
- Department of Pediatrics and Children’s Research Institute at the Medical College of Wisconsin and Children’s Hospital of Wisconsin, Milwaukee, Wisconsin, United States of America
- Department of Cell Biology, Neurobiology and Anatomy, Medical College of Wisconsin, Milwaukee, Wisconsin, United States of America
- * E-mail:
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41
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Expanding the Phenotypic Expression of Sonic Hedgehog Mutations Beyond Holoprosencephaly. J Craniofac Surg 2015; 26:3-5. [DOI: 10.1097/scs.0000000000001377] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023] Open
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42
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Marcos S, González-Lázaro M, Beccari L, Carramolino L, Martin-Bermejo MJ, Amarie O, Martín DMS, Torroja C, Bogdanović O, Doohan R, Puk O, de Angelis MH, Graw J, Gomez-Skarmeta JL, Casares F, Torres M, Bovolenta P. Meis1 coordinates a network of genes implicated in eye development and microphthalmia. Development 2015; 142:3009-20. [DOI: 10.1242/dev.122176] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/15/2015] [Accepted: 07/17/2015] [Indexed: 01/08/2023]
Abstract
Microphthalmos is a rare congenital anomaly characterized by reduced eye size and visual deficits of variable degrees. Sporadic and hereditary microphthalmos has been associated to heterozygous mutations in genes fundamental for eye development. Yet, many cases are idiopathic or await the identification of molecular causes. Here we show that haploinsufficiency of Meis1, a transcription factor with an evolutionary conserved expression in the embryonic trunk, brain and sensory organs, including the eye, causes microphthalmic traits and visual impairment, in adult mice. By combining the analysis of Meis1 loss-of-function and conditional Meis1 functional rescue with ChIP-seq and RNA-seq approaches we show that, in contrast to Meis1 preferential association with Hox-Pbx binding sites in the trunk, Meis1 binds to Hox/Pbx-independent sites during optic cup development. In the eye primordium, Meis1 coordinates, in a dose-dependent manner, retinal proliferation and differentiation by regulating genes responsible for human microphthalmia and components the Notch signalling pathway. In addition, Meis1 is required for eye patterning by controlling a set of eye territory-specific transcription factors, so that in Meis1−/− embryos boundaries among the different eye territories are shifted or blurred. We thus propose that Meis1 is at the core of a genetic network implicated in eye patterning/microphthalmia, itself representing an additional candidate for syndromic cases of these ocular malformations.
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Affiliation(s)
- Séverine Marcos
- Centro de Biología Molecular “Severo Ochoa”, CSIC-UAM, c/ Nicolás Cabrera, 1, E-28049 Madrid, Spain
- CIBER de Enfermedades Raras (CIBERER), c/ Nicolás Cabrera, 1, E-28049 Madrid, Spain
| | - Monica González-Lázaro
- Departamento de Desarrollo y Reparación Cardiovascular, Centro Nacional de Investigaciones Cardiovasculares (CNIC), c/ Melchor Fernández Almagro, 3, E-28029 Madrid, Spain
| | - Leonardo Beccari
- Centro de Biología Molecular “Severo Ochoa”, CSIC-UAM, c/ Nicolás Cabrera, 1, E-28049 Madrid, Spain
- CIBER de Enfermedades Raras (CIBERER), c/ Nicolás Cabrera, 1, E-28049 Madrid, Spain
| | - Laura Carramolino
- Departamento de Desarrollo y Reparación Cardiovascular, Centro Nacional de Investigaciones Cardiovasculares (CNIC), c/ Melchor Fernández Almagro, 3, E-28029 Madrid, Spain
| | - Maria Jesus Martin-Bermejo
- Centro de Biología Molecular “Severo Ochoa”, CSIC-UAM, c/ Nicolás Cabrera, 1, E-28049 Madrid, Spain
- CIBER de Enfermedades Raras (CIBERER), c/ Nicolás Cabrera, 1, E-28049 Madrid, Spain
| | - Oana Amarie
- Institute of Developmental Genetics Helmholtz Center Munich; D-85764 Neuherberg, Germany
| | - Daniel Mateos-San Martín
- Departamento de Desarrollo y Reparación Cardiovascular, Centro Nacional de Investigaciones Cardiovasculares (CNIC), c/ Melchor Fernández Almagro, 3, E-28029 Madrid, Spain
| | - Carlos Torroja
- Bioinformatics Unit, Centro Nacional de Investigaciones Cardiovasculares (CNIC), c/ Melchor Fernández Almagro, 3, E-28029 Madrid, Spain
| | - Ozren Bogdanović
- Centro Andaluz de Biología del Desarrollo (CABD), CSIC-UPO, Carretera de Utrera Km1, E-41013 Sevilla, Spain
- ARC Center of Excellence in Plant Energy Biology, School of Chemistry and Biochemistry, Faculty of Science, The University of Western Australia, Perth, WA 6009, Australia
| | - Roisin Doohan
- Departamento de Desarrollo y Reparación Cardiovascular, Centro Nacional de Investigaciones Cardiovasculares (CNIC), c/ Melchor Fernández Almagro, 3, E-28029 Madrid, Spain
| | - Oliver Puk
- Institute of Developmental Genetics Helmholtz Center Munich; D-85764 Neuherberg, Germany
| | | | - Jochen Graw
- Institute of Developmental Genetics Helmholtz Center Munich; D-85764 Neuherberg, Germany
| | - Jose Luis Gomez-Skarmeta
- Centro Andaluz de Biología del Desarrollo (CABD), CSIC-UPO, Carretera de Utrera Km1, E-41013 Sevilla, Spain
| | - Fernando Casares
- Centro Andaluz de Biología del Desarrollo (CABD), CSIC-UPO, Carretera de Utrera Km1, E-41013 Sevilla, Spain
| | - Miguel Torres
- Departamento de Desarrollo y Reparación Cardiovascular, Centro Nacional de Investigaciones Cardiovasculares (CNIC), c/ Melchor Fernández Almagro, 3, E-28029 Madrid, Spain
| | - Paola Bovolenta
- Centro de Biología Molecular “Severo Ochoa”, CSIC-UAM, c/ Nicolás Cabrera, 1, E-28049 Madrid, Spain
- CIBER de Enfermedades Raras (CIBERER), c/ Nicolás Cabrera, 1, E-28049 Madrid, Spain
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Wen W, Pillai-Kastoori L, Wilson SG, Morris AC. Sox4 regulates choroid fissure closure by limiting Hedgehog signaling during ocular morphogenesis. Dev Biol 2014; 399:139-153. [PMID: 25557621 DOI: 10.1016/j.ydbio.2014.12.026] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/21/2014] [Revised: 12/15/2014] [Accepted: 12/22/2014] [Indexed: 01/20/2023]
Abstract
SoxC transcription factors play critical roles in many developmental processes, including neurogenesis, cardiac formation, and skeletal differentiation. In vitro and in vivo loss-of-function studies have suggested that SoxC genes are required for oculogenesis; however the mechanism was poorly understood. Here, we have explored the function of the SoxC factor Sox4 during zebrafish eye development. We show that sox4a and sox4b are expressed in the forebrain and periocular mesenchyme adjacent to the optic stalk during early eye development. Knockdown of sox4 in zebrafish resulted in coloboma, a structural malformation of the eye that is a significant cause of pediatric visual impairment in humans, in which the choroid fissure fails to close. Sox4 morphants displayed altered proximo-distal patterning of the optic vesicle, including expanded pax2 expression in the optic stalk, as well as ectopic cell proliferation in the retina. We show that the abnormal ocular morphogenesis observed in Sox4-deficient zebrafish is caused by elevated Hedgehog (Hh) signaling, and this is due to increased expression of the Hh pathway ligand Indian Hedgehog b (ihhb). Consistent with these results, coloboma in sox4 morphants could be rescued by pharmacological treatment with the Hh inhibitor cyclopamine, or by co-knockdown of ihhb. Conversely, overexpression of sox4 reduced Hh signaling and ihhb expression, resulting in cyclopia. Finally, we demonstrate that sox4 and sox11 have overlapping, but not completely redundant, functions in regulating ocular morphogenesis. Taken together, our data demonstrate that Sox4 is required to limit the extent of Hh signaling during eye development, and suggest that mutations in SoxC factors could contribute to the development of coloboma.
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Affiliation(s)
- Wen Wen
- Department of Biology, University of Kentucky, Lexington, KY 40506-0225, USA
| | | | - Stephen G Wilson
- Department of Biology, University of Kentucky, Lexington, KY 40506-0225, USA
| | - Ann C Morris
- Department of Biology, University of Kentucky, Lexington, KY 40506-0225, USA.
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44
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Celli J. Genetics of gastrointestinal atresias. Eur J Med Genet 2014; 57:424-39. [DOI: 10.1016/j.ejmg.2014.06.007] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/22/2014] [Accepted: 06/21/2014] [Indexed: 01/04/2023]
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45
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Pillai-Kastoori L, Wen W, Wilson SG, Strachan E, Lo-Castro A, Fichera M, Musumeci SA, Lehmann OJ, Morris AC. Sox11 is required to maintain proper levels of Hedgehog signaling during vertebrate ocular morphogenesis. PLoS Genet 2014; 10:e1004491. [PMID: 25010521 PMCID: PMC4091786 DOI: 10.1371/journal.pgen.1004491] [Citation(s) in RCA: 45] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/06/2013] [Accepted: 05/21/2014] [Indexed: 11/29/2022] Open
Abstract
Ocular coloboma is a sight-threatening malformation caused by failure of the choroid fissure to close during morphogenesis of the eye, and is frequently associated with additional anomalies, including microphthalmia and cataracts. Although Hedgehog signaling is known to play a critical role in choroid fissure closure, genetic regulation of this pathway remains poorly understood. Here, we show that the transcription factor Sox11 is required to maintain specific levels of Hedgehog signaling during ocular development. Sox11-deficient zebrafish embryos displayed delayed and abnormal lens formation, coloboma, and a specific reduction in rod photoreceptors, all of which could be rescued by treatment with the Hedgehog pathway inhibitor cyclopamine. We further demonstrate that the elevated Hedgehog signaling in Sox11-deficient zebrafish was caused by a large increase in shha transcription; indeed, suppressing Shha expression rescued the ocular phenotypes of sox11 morphants. Conversely, over-expression of sox11 induced cyclopia, a phenotype consistent with reduced levels of Sonic hedgehog. We screened DNA samples from 79 patients with microphthalmia, anophthalmia, or coloboma (MAC) and identified two novel heterozygous SOX11 variants in individuals with coloboma. In contrast to wild type human SOX11 mRNA, mRNA containing either variant failed to rescue the lens and coloboma phenotypes of Sox11-deficient zebrafish, and both exhibited significantly reduced transactivation ability in a luciferase reporter assay. Moreover, decreased gene dosage from a segmental deletion encompassing the SOX11 locus resulted in microphthalmia and related ocular phenotypes. Therefore, our study reveals a novel role for Sox11 in controlling Hedgehog signaling, and suggests that SOX11 variants contribute to pediatric eye disorders.
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Affiliation(s)
- Lakshmi Pillai-Kastoori
- Department of Biology, University of Kentucky, Lexington, Kentucky, United States of America
| | - Wen Wen
- Department of Biology, University of Kentucky, Lexington, Kentucky, United States of America
| | - Stephen G. Wilson
- Department of Biology, University of Kentucky, Lexington, Kentucky, United States of America
| | - Erin Strachan
- Departments of Ophthalmology and Medical Genetics, University of Alberta, Edmonton, Alberta, Canada
| | - Adriana Lo-Castro
- Department of Neuroscience, Pediatric Neurology Unit, “Tor Vergata” University of Rome, Rome, Italy
| | - Marco Fichera
- Laboratory of Medical Genetics, IRCCS Associazione Oasi Maria Santissima, Troina, Italy, and Medical Genetics, University of Catania, Catania, Italy
| | | | - Ordan J. Lehmann
- Departments of Ophthalmology and Medical Genetics, University of Alberta, Edmonton, Alberta, Canada
| | - Ann C. Morris
- Department of Biology, University of Kentucky, Lexington, Kentucky, United States of America
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46
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Callier P, Calvel P, Matevossian A, Makrythanasis P, Bernard P, Kurosaka H, Vannier A, Thauvin-Robinet C, Borel C, Mazaud-Guittot S, Rolland A, Desdoits-Lethimonier C, Guipponi M, Zimmermann C, Stévant I, Kuhne F, Conne B, Santoni F, Lambert S, Huet F, Mugneret F, Jaruzelska J, Faivre L, Wilhelm D, Jégou B, Trainor PA, Resh MD, Antonarakis SE, Nef S. Loss of function mutation in the palmitoyl-transferase HHAT leads to syndromic 46,XY disorder of sex development by impeding Hedgehog protein palmitoylation and signaling. PLoS Genet 2014; 10:e1004340. [PMID: 24784881 PMCID: PMC4006744 DOI: 10.1371/journal.pgen.1004340] [Citation(s) in RCA: 59] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/08/2013] [Accepted: 03/07/2014] [Indexed: 12/13/2022] Open
Abstract
The Hedgehog (Hh) family of secreted proteins act as morphogens to control embryonic patterning and development in a variety of organ systems. Post-translational covalent attachment of cholesterol and palmitate to Hh proteins are critical for multimerization and long range signaling potency. However, the biological impact of lipid modifications on Hh ligand distribution and signal reception in humans remains unclear. In the present study, we report a unique case of autosomal recessive syndromic 46,XY Disorder of Sex Development (DSD) with testicular dysgenesis and chondrodysplasia resulting from a homozygous G287V missense mutation in the hedgehog acyl-transferase (HHAT) gene. This mutation occurred in the conserved membrane bound O-acyltransferase (MBOAT) domain and experimentally disrupted the ability of HHAT to palmitoylate Hh proteins such as DHH and SHH. Consistent with the patient phenotype, HHAT was found to be expressed in the somatic cells of both XX and XY gonads at the time of sex determination, and Hhat loss of function in mice recapitulates most of the testicular, skeletal, neuronal and growth defects observed in humans. In the developing testis, HHAT is not required for Sertoli cell commitment but plays a role in proper testis cord formation and the differentiation of fetal Leydig cells. Altogether, these results shed new light on the mechanisms of action of Hh proteins. Furthermore, they provide the first clinical evidence of the essential role played by lipid modification of Hh proteins in human testicular organogenesis and embryonic development. Disorders of gonadal development represent a clinically and genetically heterogeneous class of DSD caused by defects in gonadal development and/or a failure of testis/ovarian differentiation. Unfortunately, in many cases the genetic aetiology of DSD is unknown, indicating that our knowledge of the factors mediating sex determination is limited. Using exome sequencing on a case of autosomal recessive syndromic 46,XY DSD with testicular dysgenesis and chondrodysplasia, we found a homozygous missense mutation (G287V) within the coding sequence of the O-acetyl-transferase HHAT gene. The HHAT gene encodes an enzyme required for the attachment of palmitoyl residues that are critical for multimerization and long range signaling potency of hedgehog secreted proteins. We found that HHAT is widely expressed in human organs during fetal development, including testes and ovaries around the time of sex determination. In vitro assays show that G287V mutation impairs HHAT palmitoyl-transferase activity and mice lacking functional Hhat exhibit testicular dysgenesis as well as other skeletal, neuronal and growth defects that recapitulate most aspects of the syndromic 46,XY DSD patient. These data provide the first clinical evidence of the essential role played by lipid modification of Hedgehog proteins in human testicular organogenesis and embryonic development.
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Affiliation(s)
- Patrick Callier
- Department of Genetic Medicine and Development, University of Geneva Medical School, Geneva, Switzerland; FHU-TRANSLAD, Département de Génétique, Hôpital Le Bocage, CHU, Dijon, France; EA 4271 GAD Génétique des Anomalies du Développement, Université de Bourgogne, Dijon, France
| | - Pierre Calvel
- Department of Genetic Medicine and Development, University of Geneva Medical School, Geneva, Switzerland
| | - Armine Matevossian
- Cell Biology Program, Memorial Sloan-Kettering Cancer Center, New York, New York, United States of America; Gerstner Sloan-Kettering Graduate School of Biomedical Sciences, Memorial Sloan-Kettering Cancer Center, New York, New York, United States of America; Graduate Program in Pharmacology, Weill Graduate School of Medical Sciences of Cornell University, New York, New York, United States of America
| | - Periklis Makrythanasis
- Department of Genetic Medicine and Development, University of Geneva Medical School, Geneva, Switzerland
| | - Pascal Bernard
- Department of Anatomy and Developmental Biology, Monash University, Clayton, Australia
| | - Hiroshi Kurosaka
- Stowers Institute for Medical Research, Kansas City, Missouri, United States of America
| | - Anne Vannier
- Department of Genetic Medicine and Development, University of Geneva Medical School, Geneva, Switzerland
| | - Christel Thauvin-Robinet
- FHU-TRANSLAD, Département de Génétique, Hôpital Le Bocage, CHU, Dijon, France; EA 4271 GAD Génétique des Anomalies du Développement, Université de Bourgogne, Dijon, France
| | - Christelle Borel
- Department of Genetic Medicine and Development, University of Geneva Medical School, Geneva, Switzerland
| | - Séverine Mazaud-Guittot
- Institut National de la Santé et de la Recherche Médicale (Inserm) U1085-IRSET, Université de Rennes 1, Structure Fédérative Recherche Biosit, Campus de Beaulieu, Rennes, France
| | - Antoine Rolland
- Institut National de la Santé et de la Recherche Médicale (Inserm) U1085-IRSET, Université de Rennes 1, Structure Fédérative Recherche Biosit, Campus de Beaulieu, Rennes, France
| | - Christèle Desdoits-Lethimonier
- Institut National de la Santé et de la Recherche Médicale (Inserm) U1085-IRSET, Université de Rennes 1, Structure Fédérative Recherche Biosit, Campus de Beaulieu, Rennes, France
| | - Michel Guipponi
- Department of Genetic Medicine and Development, University of Geneva Medical School, Geneva, Switzerland
| | - Céline Zimmermann
- Department of Genetic Medicine and Development, University of Geneva Medical School, Geneva, Switzerland
| | - Isabelle Stévant
- Department of Genetic Medicine and Development, University of Geneva Medical School, Geneva, Switzerland
| | - Françoise Kuhne
- Department of Genetic Medicine and Development, University of Geneva Medical School, Geneva, Switzerland
| | - Béatrice Conne
- Department of Genetic Medicine and Development, University of Geneva Medical School, Geneva, Switzerland
| | - Federico Santoni
- Department of Genetic Medicine and Development, University of Geneva Medical School, Geneva, Switzerland
| | - Sandy Lambert
- FHU-TRANSLAD, Département de Génétique, Hôpital Le Bocage, CHU, Dijon, France
| | - Frederic Huet
- FHU-TRANSLAD, Département de Génétique, Hôpital Le Bocage, CHU, Dijon, France; EA 4271 GAD Génétique des Anomalies du Développement, Université de Bourgogne, Dijon, France
| | - Francine Mugneret
- FHU-TRANSLAD, Département de Génétique, Hôpital Le Bocage, CHU, Dijon, France
| | | | - Laurence Faivre
- FHU-TRANSLAD, Département de Génétique, Hôpital Le Bocage, CHU, Dijon, France; EA 4271 GAD Génétique des Anomalies du Développement, Université de Bourgogne, Dijon, France
| | - Dagmar Wilhelm
- Department of Anatomy and Developmental Biology, Monash University, Clayton, Australia
| | - Bernard Jégou
- Institut National de la Santé et de la Recherche Médicale (Inserm) U1085-IRSET, Université de Rennes 1, Structure Fédérative Recherche Biosit, Campus de Beaulieu, Rennes, France; EHESP School of Public Health, Rennes, France
| | - Paul A Trainor
- Stowers Institute for Medical Research, Kansas City, Missouri, United States of America; Department of Anatomy and Cell Biology, University of Kansas Medical Center, Kansas City, Kansas, United States of America
| | - Marilyn D Resh
- Cell Biology Program, Memorial Sloan-Kettering Cancer Center, New York, New York, United States of America; Gerstner Sloan-Kettering Graduate School of Biomedical Sciences, Memorial Sloan-Kettering Cancer Center, New York, New York, United States of America; Graduate Program in Pharmacology, Weill Graduate School of Medical Sciences of Cornell University, New York, New York, United States of America
| | - Stylianos E Antonarakis
- Department of Genetic Medicine and Development, University of Geneva Medical School, Geneva, Switzerland; iGE3, Institute of Genetics and Genomics of Geneva, University of Geneva, Geneva, Switzerland
| | - Serge Nef
- Department of Genetic Medicine and Development, University of Geneva Medical School, Geneva, Switzerland; iGE3, Institute of Genetics and Genomics of Geneva, University of Geneva, Geneva, Switzerland
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47
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Williamson K, Rainger J, Floyd J, Ansari M, Meynert A, Aldridge K, Rainger J, Anderson C, Moore A, Hurles M, Clarke A, van Heyningen V, Verloes A, Taylor M, Wilkie A, FitzPatrick D, Fitzpatrick DR. Heterozygous loss-of-function mutations in YAP1 cause both isolated and syndromic optic fissure closure defects. Am J Hum Genet 2014; 94:295-302. [PMID: 24462371 DOI: 10.1016/j.ajhg.2014.01.001] [Citation(s) in RCA: 66] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/08/2013] [Accepted: 01/02/2014] [Indexed: 01/08/2023] Open
Abstract
Exome sequence analysis of affected individuals from two families with autosomal-dominant inheritance of coloboma identified two different cosegregating heterozygous nonsense mutations (c.370C>T [p.Arg124*] and c. 1066G>T [p.Glu356*]) in YAP1. The phenotypes of the affected families differed in that one included no extraocular features and the other manifested with highly variable multisystem involvement, including hearing loss, intellectual disability, hematuria, and orofacial clefting. A combined LOD score of 4.2 was obtained for the association between YAP1 loss-of-function mutations and the phenotype in these families. YAP1 encodes an effector of the HIPPO-pathway-induced growth response, and whole-mount in situ hybridization in mouse embryos has shown that Yap1 is strongly expressed in the eye, brain, and fusing facial processes. RT-PCR showed that an alternative transcription start site (TSS) in intron 1 of YAP1 and Yap1 is widely used in human and mouse development, respectively. Transcripts from the alternative TSS are predicted to initiate at codon Met179 relative to the canonical transcript (RefSeq NM_001130145). In these alternative transcripts, the c.370C>T mutation in family 1305 is within the 5' UTR and cannot result in nonsense-mediated decay (NMD). The c. 1066G>T mutation in family 132 should result in NMD in transcripts from either TSS. Amelioration of the phenotype by the alternative transcripts provides a plausible explanation for the phenotypic differences between the families.
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Affiliation(s)
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | - David R Fitzpatrick
- Medical Research Council Human Genetics Unit, Medical Research Council Institute of Genetics and Molecular Medicine, University of Edinburgh, Edinburgh EH4 2XU, UK.
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Schimmenti LA. Genetic and developmental basis of renal coloboma (papillorenal) syndrome. EXPERT REVIEW OF OPHTHALMOLOGY 2014. [DOI: 10.1586/eop.09.3] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
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Kelberman D, Islam L, Lakowski J, Bacchelli C, Chanudet E, Lescai F, Patel A, Stupka E, Buck A, Wolf S, Beales PL, Jacques TS, Bitner-Glindzicz M, Liasis A, Lehmann OJ, Kohlhase J, Nischal KK, Sowden JC. Mutation of SALL2 causes recessive ocular coloboma in humans and mice. Hum Mol Genet 2014; 23:2511-26. [PMID: 24412933 PMCID: PMC3990155 DOI: 10.1093/hmg/ddt643] [Citation(s) in RCA: 37] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/25/2023] Open
Abstract
Ocular coloboma is a congenital defect resulting from failure of normal closure of the optic fissure during embryonic eye development. This birth defect causes childhood blindness worldwide, yet the genetic etiology is poorly understood. Here, we identified a novel homozygous mutation in the SALL2 gene in members of a consanguineous family affected with non-syndromic ocular coloboma variably affecting the iris and retina. This mutation, c.85G>T, introduces a premature termination codon (p.Glu29*) predicted to truncate the SALL2 protein so that it lacks three clusters of zinc-finger motifs that are essential for DNA-binding activity. This discovery identifies SALL2 as the third member of the Drosophila homeotic Spalt-like family of developmental transcription factor genes implicated in human disease. SALL2 is expressed in the developing human retina at the time of, and subsequent to, optic fissure closure. Analysis of Sall2-deficient mouse embryos revealed delayed apposition of the optic fissure margins and the persistence of an anterior retinal coloboma phenotype after birth. Sall2-deficient embryos displayed correct posterior closure toward the optic nerve head, and upon contact of the fissure margins, dissolution of the basal lamina occurred and PAX2, known to be critical for this process, was expressed normally. Anterior closure was disrupted with the fissure margins failing to meet, or in some cases misaligning leading to a retinal lesion. These observations demonstrate, for the first time, a role for SALL2 in eye morphogenesis and that loss of function of the gene causes ocular coloboma in humans and mice.
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