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McDonnell AF, Plech M, Livesey BJ, Gerasimavicius L, Owen LJ, Hall HN, FitzPatrick DR, Marsh JA, Kudla G. Deep mutational scanning quantifies DNA binding and predicts clinical outcomes of PAX6 variants. Mol Syst Biol 2024; 20:825-844. [PMID: 38849565 PMCID: PMC11219921 DOI: 10.1038/s44320-024-00043-8] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/04/2023] [Revised: 04/05/2024] [Accepted: 05/14/2024] [Indexed: 06/09/2024] Open
Abstract
Nonsense and missense mutations in the transcription factor PAX6 cause a wide range of eye development defects, including aniridia, microphthalmia and coloboma. To understand how changes of PAX6:DNA binding cause these phenotypes, we combined saturation mutagenesis of the paired domain of PAX6 with a yeast one-hybrid (Y1H) assay in which expression of a PAX6-GAL4 fusion gene drives antibiotic resistance. We quantified binding of more than 2700 single amino-acid variants to two DNA sequence elements. Mutations in DNA-facing residues of the N-terminal subdomain and linker region were most detrimental, as were mutations to prolines and to negatively charged residues. Many variants caused sequence-specific molecular gain-of-function effects, including variants in position 71 that increased binding to the LE9 enhancer but decreased binding to a SELEX-derived binding site. In the absence of antibiotic selection, variants that retained DNA binding slowed yeast growth, likely because such variants perturbed the yeast transcriptome. Benchmarking against known patient variants and applying ACMG/AMP guidelines to variant classification, we obtained supporting-to-moderate evidence that 977 variants are likely pathogenic and 1306 are likely benign. Our analysis shows that most pathogenic mutations in the paired domain of PAX6 can be explained simply by the effects of these mutations on PAX6:DNA association, and establishes Y1H as a generalisable assay for the interpretation of variant effects in transcription factors.
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Affiliation(s)
- Alexander F McDonnell
- MRC Human Genetics Unit, Institute of Genetics and Cancer, University of Edinburgh, Edinburgh, EH4 2XU, UK
| | - Marcin Plech
- MRC Human Genetics Unit, Institute of Genetics and Cancer, University of Edinburgh, Edinburgh, EH4 2XU, UK
| | - Benjamin J Livesey
- MRC Human Genetics Unit, Institute of Genetics and Cancer, University of Edinburgh, Edinburgh, EH4 2XU, UK
| | - Lukas Gerasimavicius
- MRC Human Genetics Unit, Institute of Genetics and Cancer, University of Edinburgh, Edinburgh, EH4 2XU, UK
| | - Liusaidh J Owen
- MRC Human Genetics Unit, Institute of Genetics and Cancer, University of Edinburgh, Edinburgh, EH4 2XU, UK
| | - Hildegard Nikki Hall
- MRC Human Genetics Unit, Institute of Genetics and Cancer, University of Edinburgh, Edinburgh, EH4 2XU, UK
| | - David R FitzPatrick
- MRC Human Genetics Unit, Institute of Genetics and Cancer, University of Edinburgh, Edinburgh, EH4 2XU, UK
| | - Joseph A Marsh
- MRC Human Genetics Unit, Institute of Genetics and Cancer, University of Edinburgh, Edinburgh, EH4 2XU, UK
| | - Grzegorz Kudla
- MRC Human Genetics Unit, Institute of Genetics and Cancer, University of Edinburgh, Edinburgh, EH4 2XU, UK.
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Chandrasekaran P, Weiskirchen S, Weiskirchen R. Structure, Functions, and Implications of Selected Lipocalins in Human Disease. Int J Mol Sci 2024; 25:4290. [PMID: 38673873 PMCID: PMC11050150 DOI: 10.3390/ijms25084290] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/20/2024] [Revised: 04/07/2024] [Accepted: 04/10/2024] [Indexed: 04/28/2024] Open
Abstract
The lipocalin proteins are a large family of small extracellular proteins that demonstrate significant heterogeneity in sequence similarity and have highly conserved crystal structures. They have a variety of functions, including acting as carrier proteins, transporting retinol, participating in olfaction, and synthesizing prostaglandins. Importantly, they also play a critical role in human diseases, including cancer. Additionally, they are involved in regulating cellular homeostasis and immune response and dispensing various compounds. This comprehensive review provides information on the lipocalin family, including their structure, functions, and implications in various diseases. It focuses on selective important human lipocalin proteins, such as lipocalin 2 (LCN2), retinol binding protein 4 (RBP4), prostaglandin D2 synthase (PTGDS), and α1-microglobulin (A1M).
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Affiliation(s)
| | - Sabine Weiskirchen
- Institute of Molecular Pathobiochemistry, Experimental Gene Therapy and Clinical Chemistry (IFMPEGKC), Rheinisch-Westfälische Technische Hochschule (RWTH) University Hospital Aachen, D-52074 Aachen, Germany;
| | - Ralf Weiskirchen
- Institute of Molecular Pathobiochemistry, Experimental Gene Therapy and Clinical Chemistry (IFMPEGKC), Rheinisch-Westfälische Technische Hochschule (RWTH) University Hospital Aachen, D-52074 Aachen, Germany;
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Plaisancié J, Martinovic J, Chesneau B, Whalen S, Rodriguez D, Audebert-Bellanger S, Marzin P, Grotto S, Perthus I, Holt RJ, Bax DA, Ragge N, Chassaing N. Clinical, genetic and biochemical signatures of RBP4-related ocular malformations. J Med Genet 2023; 61:84-92. [PMID: 37586836 DOI: 10.1136/jmg-2023-109331] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/12/2023] [Accepted: 07/16/2023] [Indexed: 08/18/2023]
Abstract
BACKGROUND The retinoic acid (RA) pathway plays a crucial role in both eye morphogenesis and the visual cycle. Individuals with monoallelic and biallelic pathogenic variants in retinol-binding protein 4 (RBP4), encoding a serum retinol-specific transporter, display variable ocular phenotypes. Although few families have been reported worldwide, recessive inherited variants appear to be associated with retinal degeneration, while individuals with dominantly inherited variants manifest ocular development anomalies, mainly microphthalmia, anophthalmia and coloboma (MAC). METHODS We report here seven new families (13 patients) with isolated and syndromic MAC harbouring heterozygous RBP4 variants, of whom we performed biochemical analyses. RESULTS For the first time, malformations that overlap the clinical spectrum of vitamin A deficiency are reported, providing a link with other RA disorders. Our data support two distinct phenotypes, depending on the nature and mode of inheritance of the variants: dominantly inherited, almost exclusively missense, associated with ocular malformations, in contrast to recessive, mainly truncating, associated with retinal degeneration. Moreover, we also confirm the skewed inheritance and impact of maternal RBP4 genotypes on phenotypical expression in dominant forms, suggesting that maternal RBP4 genetic status and content of diet during pregnancy may modify MAC occurrence and severity. Furthermore, we demonstrate that retinol-binding protein blood dosage in patients could provide a biological signature crucial for classifying RBP4 variants. Finally, we propose a novel hypothesis to explain the mechanisms underlying the observed genotype-phenotype correlations in RBP4 mutational spectrum. CONCLUSION Dominant missense variants in RBP4 are associated with MAC of incomplete penetrance with maternal inheritance through a likely dominant-negative mechanism.
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Affiliation(s)
- Julie Plaisancié
- Laboratoire National de Référence (LBMR), Génétique des anomalies malformatives de l'œil, CHU Toulouse, Toulouse, France
- Unité ToNIC Inserm 1214, CHU Toulouse, Toulouse, France
- Centre de Référence pour les Affections Rares en Génétique Ophtalmologique (CARGO), CHU Toulouse, Toulouse, France
| | - Jelena Martinovic
- Département de Génétique, Unité de Fœtopathologie, Hopital Necker-Enfants Malades, Paris, France
| | - Bertrand Chesneau
- Laboratoire National de Référence (LBMR), Génétique des anomalies malformatives de l'œil, CHU Toulouse, Toulouse, France
- Centre de Référence pour les Affections Rares en Génétique Ophtalmologique (CARGO), CHU Toulouse, Toulouse, France
| | - Sandra Whalen
- Genetique Medicale, Hopital Armand-Trousseau, Paris, France
| | - Diana Rodriguez
- Département de Génétique, Hôpitaux Universitaires Paris Ile-de-France Ouest, Paris, France
| | | | - Pauline Marzin
- Fédération de Génétique et Médecine Génomique, Service de Médecine Génomique des Maladies Rares, Necker-Enfants Malades Hospitals, Paris, France
| | - Sarah Grotto
- Maternité Port-Royal, FHU PREMA, Hôpital Cochin, Paris, France
| | - Isabelle Perthus
- Centre d'Etude des Malformations Congénitales en Auvergne, Génétique Médicale, CHU Estaing, Clermont-Ferrand, France
| | - Richard James Holt
- Faculty of Health and Life Sciences, Oxford Brookes University, Oxford, UK
| | - Dorine A Bax
- Faculty of Health and Life Sciences, Oxford Brookes University, Oxford, UK
| | - Nicola Ragge
- Faculty of Health and Life Sciences, Oxford Brookes University, Oxford, UK
- West Midlands Regional Genetics Service, Birmingham Women's and Children's NHS Foundation Trust, Birmingham, UK
| | - Nicolas Chassaing
- Laboratoire National de Référence (LBMR), Génétique des anomalies malformatives de l'œil, CHU Toulouse, Toulouse, France
- Centre de Référence pour les Affections Rares en Génétique Ophtalmologique (CARGO), CHU Toulouse, Toulouse, France
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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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Seese SE, Muheisen S, Gath N, Gross JM, Semina EV. Identification of HSPA8 as an interacting partner of MAB21L2 and an important factor in eye development. Dev Dyn 2023; 252:510-526. [PMID: 36576422 PMCID: PMC10947772 DOI: 10.1002/dvdy.560] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/19/2022] [Revised: 11/04/2022] [Accepted: 11/18/2022] [Indexed: 12/29/2022] Open
Abstract
BACKGROUND Pathogenic variants in human MAB21L2 result in microphthalmia, anophthalmia, and coloboma. The exact molecular function of MAB21L2 is currently unknown. We conducted a series of yeast two-hybrid (Y2H) experiments to determine protein interactomes of normal human and zebrafish MAB21L2/mab21l2 as well as human disease-associated variant MAB21L2-p.(Arg51Gly) using human adult retina and zebrafish embryo libraries. RESULTS These screens identified klhl31, tnpo1, TNPO2/tnpo2, KLC2/klc2, and SPTBN1/sptbn1 as co-factors of MAB21L2/mab21l2. Several factors, including hspa8 and hspa5, were found to interact with MAB21L2-p.Arg51Gly but not wild-type MAB21L2/mab21l2 in Y2H screens. Further analyses via 1-by-1 Y2H assays, co-immunoprecipitation, and mass spectrometry revealed that both normal and variant MAB21L2 interact with HSPA5 and HSPA8. In situ hybridization detected co-expression of hspa5 and hspa8 with mab21l2 during eye development in zebrafish. Examination of zebrafish mutant hspa8hi138Tg identified reduced hspa8 expression associated with severe ocular developmental defects, including small eye, coloboma, and anterior segment dysgenesis. To investigate the effects of hspa8 deficiency on the mab21l2Arg51_Phe52del allele, corresponding zebrafish double mutants were generated and found to be more severely affected than single mutant lines. CONCLUSION This study identifies heat shock proteins as interacting partners of MAB21L2/mab21l2 and suggests a role for this interaction in vertebrate eye development.
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Affiliation(s)
- Sarah E. Seese
- Department of Pediatrics The Medical College of Wisconsin, Milwaukee, WI 53226, USA
- Cell Biology, Neurobiology and Anatomy, The Medical College of Wisconsin, Milwaukee, WI 53226, USA
| | - Sanaa Muheisen
- Department of Pediatrics The Medical College of Wisconsin, Milwaukee, WI 53226, USA
| | - Natalie Gath
- University of Pittsburgh School of Medicine, Pittsburgh, PA 15213, USA
| | - Jeffrey M. Gross
- University of Pittsburgh School of Medicine, Pittsburgh, PA 15213, USA
| | - Elena V. Semina
- Department of Pediatrics The Medical College of Wisconsin, Milwaukee, WI 53226, USA
- Cell Biology, Neurobiology and Anatomy, The Medical College of Wisconsin, Milwaukee, WI 53226, USA
- Department of Ophthalmology and Visual Sciences, Medical College of Wisconsin, Children’s of Wisconsin, Milwaukee, WI 53226, USA
- Children’s Research Institute, Medical College of Wisconsin, Children’s of Wisconsin, Milwaukee, WI 53226, USA
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Kaur A, Daniel R, Kumari S. Maternal transmission of RBP4 congenital eye disease: can Vitamin A help? Ophthalmic Genet 2023; 44:107-108. [PMID: 36342076 DOI: 10.1080/13816810.2022.2141793] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Affiliation(s)
- Anupriya Kaur
- Genetic and Metabolic Unit, Department of Paediatrics, PGIMER, Chandigarh, India
| | - Roshan Daniel
- Genetic and Metabolic Unit, Department of Paediatrics, PGIMER, Chandigarh, India
| | - Snigdha Kumari
- Genetic and Metabolic Unit, Department of Paediatrics, PGIMER, Chandigarh, India.,Department of Obstetrics and Gynecology, PGIMER, Chandigarh
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Kessel L, Bertelsen M, Grønskov K. RBP4-related eye disease in a Danish family with retinitis pigmentosa and congenital ocular malformations. Ophthalmic Genet 2022; 43:876-881. [PMID: 36317196 DOI: 10.1080/13816810.2022.2141789] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
PURPOSE Retinol binding protein (RBP4) is important for transport of vitamin A from liver to end organs. Variants in the RBP4 gene have been associated with a broad range of ocular phenotypes but only in a small number of patients. METHODS We describe the phenotypes in a multi-generation family with RPB4 variants. RESULTS A sibling pair was found to be homozygous for a novel pathogenic variant (c.112-2A>G) in RBP4. Both had presented with early-onset atypical retinitis pigmentosa and they had rheumatoid arthritis and acne. The female sibling became the mother of a child, heterozygote for the variant. The child was born with ocular malformations including corneal opacities, microcornea, posterior staphyloma including the optic nerves. The child did not demonstrate any signs of night blindness or progressive retinal dystrophy. In addition, two older family members were reported to be night blind and two distant relatives were born with spina bifida but were not available for genetic testing. DISCUSSION Homozygous variants were associated with severe retinal dystrophy, rheumatoid disease, and acne whereas malformations were likely associated with reduced intra-uterine vitamin A levels. It seems advisable to monitor and treat vitamin A deficiency in all patients carrying one or more variants in the RBP4 gene especially during pregnancy.
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Affiliation(s)
- Line Kessel
- Department of Ophthalmology, Rigshospitalet, Glostrup, Denmark.,Department of Clinical Medicine, University of Copenhagen, Copenhagen, Denmark
| | - Mette Bertelsen
- Department of Clinical Genetics, Rigshospitalet, Glostrup, Denmark
| | - Karen Grønskov
- Department of Clinical Genetics, Rigshospitalet, Glostrup, Denmark
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Montenegro D, Zhao J, Kim HJ, Shmarakov IO, Blaner WS, Sparrow JR. Products of the visual cycle are detected in mice lacking retinol binding protein 4, the only known vitamin A carrier in plasma. J Biol Chem 2022; 298:102722. [PMID: 36410431 PMCID: PMC9768380 DOI: 10.1016/j.jbc.2022.102722] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2022] [Revised: 11/01/2022] [Accepted: 11/14/2022] [Indexed: 11/21/2022] Open
Abstract
Efficient delivery of vitamin A to the retinal pigment epithelium is vital to the production of the light-sensitive visual chromophore 11-cis-retinal. Nevertheless, retinol binding protein 4 (RBP4) is the only known carrier of vitamin A in plasma. Here, we present new findings that further characterize the visual cycle in the presence of Rbp4 deficiency. In the face of impaired delivery of retinol in Rbp4-/- mice, we determined that 11-cis-retinaldehyde reached levels that were ∼60% of WT at 4 months of age and all-trans-retinyl ester was 18% of normal yet photoreceptor cell loss was apparent by 8 months of age. The lack of Rbp4 appeared to have a greater impact on scotopic rod-mediated responses than on cone function at early ages. Also, despite severely impaired delivery of retinol, bisretinoid lipofuscin that forms as a byproduct of the visual cycle was measurable by HPLC and by quantitative fundus autofluorescence. In mice carrying an Rpe65 amino acid variant that slows visual cycle kinetics, Rbp4 deficiency had a less pronounced effect on 11-cis-retinal levels. Finally, we found that ocular retinoids were not altered in mice expressing elevated adipose-derived total Rbp4 protein (hRBP4+/+AdiCre+/-). In conclusion, our findings are consistent with a model in which vitamin A can be delivered to the retina by Rbp4-independent pathways.
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Affiliation(s)
- Diego Montenegro
- Departments of Ophthalmology, Columbia University Medical Center, New York, New York, USA
| | - Jin Zhao
- Departments of Ophthalmology, Columbia University Medical Center, New York, New York, USA
| | - Hye Jin Kim
- Departments of Ophthalmology, Columbia University Medical Center, New York, New York, USA
| | - Igor O Shmarakov
- Departments of Medicine, Columbia University Medical Center, New York, New York, USA
| | - William S Blaner
- Departments of Medicine, Columbia University Medical Center, New York, New York, USA
| | - Janet R Sparrow
- Departments of Ophthalmology, Columbia University Medical Center, New York, New York, USA; Departments of Pathology and Cell Biology, Columbia University Medical Center, New York, New York, USA.
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Meng F, Li X, Zhang J, Gao Z, Yang X, Liu Z, Liu Y, Guo T, Wang L, Yang L, Wang Z. Single amino acid variation in MAB21L1 is dominantly associated with congenital eye defects. J Med Genet 2022:jmg-2022-108506. [DOI: 10.1136/jmg-2022-108506] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/14/2022] [Accepted: 10/19/2022] [Indexed: 11/30/2022]
Abstract
BackgroundDiagnosis of a genetic disease and determination of the causative molecular lesion rely on the availability of the disease-associated pedigrees. Microphthalmia is a congenital eye defect due to an insufficiently developed visual system; its prevalence is 1–3 in 10 000 live births.ObjectiveWe analysed a pedigree exhibiting autosomal dominant inheritance of microphthalmia to determine the genetic lesion; used AlphaFold2 to predict the changes in the protein’s 3-Dimensional structure; and compared wild-type and variant proteins in cultured cells or Drosophila model was used to explore the cellular or developmental function of the encoded product.ResultsWe identified a novel missense variation, F52L, in MAB21L1 that is absent in population databases and present exclusively in the individuals diagnosed with microphthalmia in this pedigree. Common structural changes were predicted for the disease-associated variants clustered at amino acids 49–52, and these variant products were also predominantly trapped in the cytoplasm of cultured human lens epithelia. To recapitulate its dominant effect in development, we expressed the Drosophila homologue corresponding to MAB21L1F52Land caused malformation of sensory organs.ConclusionMutations at the residues 49–52 of MAB21L1 compromise eye development. We recommend includingMAB21L1in the genetic testing panel for congenital eye disorders.
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Diacou R, Nandigrami P, Fiser A, Liu W, Ashery-Padan R, Cvekl A. Cell fate decisions, transcription factors and signaling during early retinal development. Prog Retin Eye Res 2022; 91:101093. [PMID: 35817658 PMCID: PMC9669153 DOI: 10.1016/j.preteyeres.2022.101093] [Citation(s) in RCA: 28] [Impact Index Per Article: 14.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/05/2022] [Revised: 06/02/2022] [Accepted: 06/03/2022] [Indexed: 12/30/2022]
Abstract
The development of the vertebrate eyes is a complex process starting from anterior-posterior and dorso-ventral patterning of the anterior neural tube, resulting in the formation of the eye field. Symmetrical separation of the eye field at the anterior neural plate is followed by two symmetrical evaginations to generate a pair of optic vesicles. Next, reciprocal invagination of the optic vesicles with surface ectoderm-derived lens placodes generates double-layered optic cups. The inner and outer layers of the optic cups develop into the neural retina and retinal pigment epithelium (RPE), respectively. In vitro produced retinal tissues, called retinal organoids, are formed from human pluripotent stem cells, mimicking major steps of retinal differentiation in vivo. This review article summarizes recent progress in our understanding of early eye development, focusing on the formation the eye field, optic vesicles, and early optic cups. Recent single-cell transcriptomic studies are integrated with classical in vivo genetic and functional studies to uncover a range of cellular mechanisms underlying early eye development. The functions of signal transduction pathways and lineage-specific DNA-binding transcription factors are dissected to explain cell-specific regulatory mechanisms underlying cell fate determination during early eye development. The functions of homeodomain (HD) transcription factors Otx2, Pax6, Lhx2, Six3 and Six6, which are required for early eye development, are discussed in detail. Comprehensive understanding of the mechanisms of early eye development provides insight into the molecular and cellular basis of developmental ocular anomalies, such as optic cup coloboma. Lastly, modeling human development and inherited retinal diseases using stem cell-derived retinal organoids generates opportunities to discover novel therapies for retinal diseases.
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Affiliation(s)
- Raven Diacou
- Department of Genetics, Albert Einstein College of Medicine, Bronx, NY, 10461, USA; Department of Ophthalmology and Visual Sciences, Albert Einstein College of Medicine, Bronx, NY, 10461, USA
| | - Prithviraj Nandigrami
- Department of Systems and Computational Biology, Albert Einstein College of Medicine, Bronx, NY, 10461, USA; Department of Biochemistry, Albert Einstein College of Medicine, Bronx, NY, 10461, USA
| | - Andras Fiser
- Department of Systems and Computational Biology, Albert Einstein College of Medicine, Bronx, NY, 10461, USA; Department of Biochemistry, Albert Einstein College of Medicine, Bronx, NY, 10461, USA
| | - Wei Liu
- Department of Genetics, Albert Einstein College of Medicine, Bronx, NY, 10461, USA; Department of Ophthalmology and Visual Sciences, Albert Einstein College of Medicine, Bronx, NY, 10461, USA
| | - Ruth Ashery-Padan
- Sackler School of Medicine, Tel Aviv University, Tel Aviv, 69978, Israel
| | - Ales Cvekl
- Department of Genetics, Albert Einstein College of Medicine, Bronx, NY, 10461, USA; Department of Ophthalmology and Visual Sciences, Albert Einstein College of Medicine, Bronx, NY, 10461, USA.
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Mice Lacking the Systemic Vitamin A Receptor RBPR2 Show Decreased Ocular Retinoids and Loss of Visual Function. Nutrients 2022; 14:nu14122371. [PMID: 35745101 PMCID: PMC9231411 DOI: 10.3390/nu14122371] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/22/2022] [Revised: 05/31/2022] [Accepted: 06/03/2022] [Indexed: 02/05/2023] Open
Abstract
Simple Summary This work represents an initial evaluation of the second RBP4-vitamin A receptor RBPR2 in a mammalian model. We provide evidence that the membrane localized RBPR2 protein, under variable conditions of dietary vitamin A intake, plays an important role for dietary vitamin A transport to the eye for ocular retinoid homeostasis and visual function. These findings are of general interest, as disturbances in blood and ocular vitamin A homeostasis are linked to retinal degenerative diseases, which are blinding diseases. The animal model described here could also serve as an in vivo tool to study mechanisms related to retinal cell degeneration that are associated with vitamin A deficiency. Abstract The systemic transport of dietary vitamin A/all-trans retinol bound to RBP4 into peripheral tissues for storage is an essential physiological process that continuously provides visual chromophore precursors to the retina under fasting conditions. This mechanism is critical for phototransduction, photoreceptor cell maintenance and survival, and in the support of visual function. While the membrane receptor STRA6 facilitates the blood transport of lipophilic vitamin A into the eye, it is not expressed in most peripheral organs, which are proposed to express a second membrane receptor for the uptake of vitamin A from circulating RBP4. The discovery of a novel vitamin A receptor, RBPR2, which is expressed in the liver and intestine, but not in the eye, alluded to this long-sort non-ocular membrane receptor for systemic RBP4-ROL uptake and transport. We have previously shown in zebrafish that the retinol-binding protein receptor 2 (Rbpr2) plays an important role in the transport of yolk vitamin A to the eye. Mutant rbpr2 zebrafish lines manifested in decreased ocular retinoid concentrations and retinal phenotypes. To investigate a physiological role for the second vitamin A receptor, RBPR2, in mammals and to analyze the metabolic basis of systemic vitamin A transport for retinoid homeostasis, we established a whole-body Rbpr2 knockout mouse (Rbpr2−/−) model. These mice were viable on both vitamin A-sufficient and -deficient diets. Rbpr2−/− mice that were fed a vitamin A-sufficient diet displayed lower ocular retinoid levels, decreased opsins, and manifested in decrease visual function, as measured by electroretinography. Interestingly, when Rbpr2−/− mice were fed a vitamin A-deficient diet, they additionally showed shorter photoreceptor outer segment phenotypes, altogether manifesting in a significant loss of visual function. Thus, under conditions replicating vitamin A sufficiency and deficiency, our analyses revealed that RBPR2-mediated systemic vitamin A transport is a regulated process that is important for vitamin A delivery to the eye when RBP4-bound ROL is the only transport pathway in the fasting condition or under vitamin A deficiency conditions.
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Steinhoff JS, Lass A, Schupp M. Retinoid Homeostasis and Beyond: How Retinol Binding Protein 4 Contributes to Health and Disease. Nutrients 2022; 14:1236. [PMID: 35334893 PMCID: PMC8951293 DOI: 10.3390/nu14061236] [Citation(s) in RCA: 11] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/24/2022] [Revised: 03/09/2022] [Accepted: 03/11/2022] [Indexed: 02/06/2023] Open
Abstract
Retinol binding protein 4 (RBP4) is the specific transport protein of the lipophilic vitamin A, retinol, in blood. Circulating RBP4 originates from the liver. It is secreted by hepatocytes after it has been loaded with retinol and binding to transthyretin (TTR). TTR association prevents renal filtration due to the formation of a higher molecular weight complex. In the circulation, RBP4 binds to specific membrane receptors, thereby delivering retinol to target cells, rendering liver-secreted RBP4 the major mechanism to distribute hepatic vitamin A stores to extrahepatic tissues. In particular, binding of RBP4 to 'stimulated by retinoic acid 6' (STRA6) is required to balance tissue retinoid responses in a highly homeostatic manner. Consequently, defects/mutations in RBP4 can cause a variety of conditions and diseases due to dysregulated retinoid homeostasis and cover embryonic development, vision, metabolism, and cardiovascular diseases. Aside from the effects related to retinol transport, non-canonical functions of RBP4 have also been reported. In this review, we summarize the current knowledge on the regulation and function of RBP4 in health and disease derived from murine models and human mutations.
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Affiliation(s)
- Julia S. Steinhoff
- Charité—Universitätsmedizin Berlin, Corporate Member of Freie Universität Berlin and Humboldt-Universität zu Berlin, Institute of Pharmacology, Cardiovascular Metabolic Renal (CMR)-Research Center, 10115 Berlin, Germany;
| | - Achim Lass
- Institute of Molecular Biosciences, NAWI Graz, University of Graz, Heinrichstraße 31/II, A-8010 Graz, Austria;
- Field of Excellence BioHealth, University of Graz, Heinrichstraße 31/II, A-8010 Graz, Austria
| | - Michael Schupp
- Charité—Universitätsmedizin Berlin, Corporate Member of Freie Universität Berlin and Humboldt-Universität zu Berlin, Institute of Pharmacology, Cardiovascular Metabolic Renal (CMR)-Research Center, 10115 Berlin, Germany;
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13
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The Role of Vitamin A in Retinal Diseases. Int J Mol Sci 2022; 23:ijms23031014. [PMID: 35162940 PMCID: PMC8835581 DOI: 10.3390/ijms23031014] [Citation(s) in RCA: 23] [Impact Index Per Article: 11.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/19/2021] [Revised: 01/12/2022] [Accepted: 01/13/2022] [Indexed: 12/24/2022] Open
Abstract
Vitamin A is an essential fat-soluble vitamin that occurs in various chemical forms. It is essential for several physiological processes. Either hyper- or hypovitaminosis can be harmful. One of the most important vitamin A functions is its involvement in visual phototransduction, where it serves as the crucial part of photopigment, the first molecule in the process of transforming photons of light into electrical signals. In this process, large quantities of vitamin A in the form of 11-cis-retinal are being isomerized to all-trans-retinal and then quickly recycled back to 11-cis-retinal. Complex machinery of transporters and enzymes is involved in this process (i.e., the visual cycle). Any fault in the machinery may not only reduce the efficiency of visual detection but also cause the accumulation of toxic chemicals in the retina. This review provides a comprehensive overview of diseases that are directly or indirectly connected with vitamin A pathways in the retina. It includes the pathophysiological background and clinical presentation of each disease and summarizes the already existing therapeutic and prospective interventions.
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14
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Selzer EB, Blain D, Hufnagel RB, Lupo PJ, Mitchell LE, Brooks BP. Review of Evidence for Environmental Causes of Uveal Coloboma. Surv Ophthalmol 2021; 67:1031-1047. [PMID: 34979194 DOI: 10.1016/j.survophthal.2021.12.008] [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: 04/19/2021] [Revised: 12/22/2021] [Accepted: 12/27/2021] [Indexed: 10/19/2022]
Abstract
Uveal coloboma is a condition defined by missing ocular tissues and is a significant cause of childhood blindness. It occurs from a failure of the optic fissure to close during embryonic development,and may lead to missing parts of the iris, ciliary body, retina, choroid, and optic nerve. Because there is no treatment for coloboma, efforts have focused on prevention. While several genetic causes of coloboma have been identified, little definitive research exists regarding the environmental causes of this condition. We review the current literature on environmental factors associated with coloboma in an effort to guide future research and preventative counseling related to this condition.
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Affiliation(s)
- Evan B Selzer
- Ophthalmic Genetics & Visual Function Branch, National Eye Institute, National Institutes of Health, Bethesda, MD
| | - Delphine Blain
- Ophthalmic Genetics & Visual Function Branch, National Eye Institute, National Institutes of Health, Bethesda, MD
| | - Robert B Hufnagel
- Ophthalmic Genetics & Visual Function Branch, National Eye Institute, National Institutes of Health, Bethesda, MD
| | - Philip J Lupo
- Department of Pediatrics, Section of Hematology-Oncology, Baylor College of Medicine, Houston, TX
| | - Laura E Mitchell
- Department of Epidemiology, Human Genetics and Environmental Sciences, UTHealth School of Public Health, Houston, TX
| | - Brian P Brooks
- Ophthalmic Genetics & Visual Function Branch, National Eye Institute, National Institutes of Health, Bethesda, MD.
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15
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Xu J, Zhang JN, Sun BH, Liu Q, Ma J, Zhang Q, Liu YX, Chen N, Chen F. The role of genotype and diet in shaping gut microbiome in a genetic vitamin A deficient mouse model. J Genet Genomics 2021; 49:155-164. [PMID: 34537414 DOI: 10.1016/j.jgg.2021.08.015] [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: 05/05/2021] [Revised: 08/25/2021] [Accepted: 08/26/2021] [Indexed: 12/26/2022]
Abstract
Multifactors have been reported to affect the gut microbiome, including genotype, age, diet, and nutrition. However, few reports have investigated the relative capacity of different factors to shape the gut microbiome in a single study. Our design used a genetic vitamin A-deficient mouse model, the Rbp4-/- mouse, feeding with the low vitamin A diets at different ages of initiation (4 or 7 weeks) for 28 days. Fecal samples were collected for bacterial profiling at seven time points after diet controlling. With RBP4 depletion, Akkermansia decreased and Bacteroides increased, whereas Desulfovibrio, Barnesiella, Clostridium_XlVa, and Lactobacillus fluctuated. The bacterial community swiftly adjusted with the vitamin A-deficient diet administration and gradually changed (e.g., decrease of Barnesiella and increase of Desulfovibrio). Age exerted a relatively weaker but long-last influence. At an earlier age to feed a vitamin A-deficient diet, a higher microbial dysbiosis index will be valued. Of note, the shaping effects of diet and age on the bacterial community varied with the difference of genotype, which might indicate a greater role of genotype than diet and age in shaping the gut microbiome.
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Affiliation(s)
- Jun Xu
- Department of Gastroenterology, Peking University People's Hospital, Beijing 100044, China; Clinical Center of Immune-Mediated Digestive Diseases, Peking University People's Hospital, Beijing 100044, China; Institute of Clinical Molecular Biology & Central Laboratory, Peking University People's Hospital, Beijing 100044, China
| | - Jie-Ni Zhang
- Department of Orthodontics, Peking University School of Stomatology, Beijing 100081, China
| | - Bo-Hui Sun
- Department of Orthodontics, Peking University School of Stomatology, Beijing 100081, China
| | - Qing Liu
- Department of Gastroenterology, Peking University People's Hospital, Beijing 100044, China; Clinical Center of Immune-Mediated Digestive Diseases, Peking University People's Hospital, Beijing 100044, China
| | - Juan Ma
- Department of Gastroenterology, Peking University People's Hospital, Beijing 100044, China; Clinical Center of Immune-Mediated Digestive Diseases, Peking University People's Hospital, Beijing 100044, China
| | - Qian Zhang
- Central Laboratory, Peking University School of Stomatology, Beijing 100081, China
| | - Yong-Xin Liu
- CAS Center for Excellence in Biotic Interactions, Chinese Academy of Sciences, Beijing 100049, China
| | - Ning Chen
- Department of Gastroenterology, Peking University People's Hospital, Beijing 100044, China; Clinical Center of Immune-Mediated Digestive Diseases, Peking University People's Hospital, Beijing 100044, China.
| | - Feng Chen
- Department of Orthodontics, Peking University School of Stomatology, Beijing 100081, China; Central Laboratory, Peking University School of Stomatology, Beijing 100081, China.
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16
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Dehghan Tezerjani M, Fathi Dizaji B, Metanat Z, Vahidi Mehrjardi MY. Incomplete penetrance of autosomal recessive anophthalmia in a large consanguineous family. Ophthalmic Genet 2021; 42:787-789. [PMID: 34287093 DOI: 10.1080/13816810.2021.1955276] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/20/2022]
Affiliation(s)
- Masoud Dehghan Tezerjani
- Abortion Research Centre, Yazd Reproductive Sciences Institute, Shahid Sadoughi University of Medical Science, Yazd, Iran
| | - Behdokht Fathi Dizaji
- Department of Medical Genetics, Faculty of Medicine, Mashhad University of Medical Sciences, Mashhad, Iran
| | - Zahra Metanat
- Provincial Clinical Genetic Counseling Center, Zahedan University of Medical Sciences, Zahedan, Iran
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Nono Nankam PA, Blüher M. Retinol-binding protein 4 in obesity and metabolic dysfunctions. Mol Cell Endocrinol 2021; 531:111312. [PMID: 33957191 DOI: 10.1016/j.mce.2021.111312] [Citation(s) in RCA: 36] [Impact Index Per Article: 12.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/02/2021] [Revised: 04/28/2021] [Accepted: 04/29/2021] [Indexed: 12/11/2022]
Abstract
Excessive increased adipose tissue mass in obesity is associated with numerous co-morbid disorders including increased risk of type 2 diabetes, fatty liver disease, hypertension, dyslipidemia, cardiovascular diseases, dementia, airway disease and some cancers. The causal mechanisms explaining these associations are not fully understood. Adipose tissue is an active endocrine organ that secretes many adipokines, cytokines and releases metabolites. These biomolecules referred to as adipocytokines play a significant role in the regulation of whole-body energy homeostasis and metabolism by influencing and altering target tissues function. Understanding the mechanisms of adipocytokine actions represents a hot topic in obesity research. Among several secreted bioactive signalling molecules from adipose tissue and liver, retinol-binding protein 4 (RBP4) has been associated with systemic insulin resistance, dyslipidemia, type 2 diabetes and other metabolic diseases. Here, we aim to review and discuss the current knowledge on RBP4 with a focus on its role in the pathogenesis of obesity comorbid diseases.
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Affiliation(s)
- Pamela A Nono Nankam
- Helmholtz Institute for Metabolic, Obesity and Vascular Research (HI-MAG) of the Helmholtz Zentrum München at the University of Leipzig and University Hospital Leipzig, Germany.
| | - Matthias Blüher
- Helmholtz Institute for Metabolic, Obesity and Vascular Research (HI-MAG) of the Helmholtz Zentrum München at the University of Leipzig and University Hospital Leipzig, Germany; Medical Department III - Endocrinology, Nephrology, Rheumatology, University of Leipzig Medical Center, Germany
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18
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Steinhoff JS, Lass A, Schupp M. Biological Functions of RBP4 and Its Relevance for Human Diseases. Front Physiol 2021; 12:659977. [PMID: 33790810 PMCID: PMC8006376 DOI: 10.3389/fphys.2021.659977] [Citation(s) in RCA: 65] [Impact Index Per Article: 21.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/28/2021] [Accepted: 02/22/2021] [Indexed: 12/13/2022] Open
Abstract
Retinol binding protein 4 (RBP4) is a member of the lipocalin family and the major transport protein of the hydrophobic molecule retinol, also known as vitamin A, in the circulation. Expression of RBP4 is highest in the liver, where most of the body’s vitamin A reserves are stored as retinyl esters. For the mobilization of vitamin A from the liver, retinyl esters are hydrolyzed to retinol, which then binds to RBP4 in the hepatocyte. After associating with transthyretin (TTR), the retinol/RBP4/TTR complex is released into the bloodstream and delivers retinol to tissues via binding to specific membrane receptors. So far, two distinct RBP4 receptors have been identified that mediate the uptake of retinol across the cell membrane and, under specific conditions, bi-directional retinol transport. Although most of RBP4’s actions depend on its role in retinoid homeostasis, functions independent of retinol transport have been described. In this review, we summarize and discuss the recent findings on the structure, regulation, and functions of RBP4 and lay out the biological relevance of this lipocalin for human diseases.
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Affiliation(s)
- Julia S Steinhoff
- Institute of Pharmacology, Charité-Universitätsmedizin Berlin, Corporate Member of Freie Universität Berlin, Humboldt-Universität zu Berlin, and Berlin Institute of Health, Berlin, Germany
| | - Achim Lass
- Institute of Molecular Biosciences, NAWI Graz, University of Graz, Graz, Austria.,BioTechMed-Graz, Graz, Austria
| | - Michael Schupp
- Institute of Pharmacology, Charité-Universitätsmedizin Berlin, Corporate Member of Freie Universität Berlin, Humboldt-Universität zu Berlin, and Berlin Institute of Health, Berlin, Germany
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19
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Patel A, Anderson G, Galea GL, Balys M, Sowden JC. A molecular and cellular analysis of human embryonic optic fissure closure related to the eye malformation coloboma. Development 2020; 147:dev193649. [PMID: 33158926 DOI: 10.1242/dev.193649] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/03/2020] [Accepted: 10/30/2020] [Indexed: 12/28/2022]
Abstract
Ocular coloboma is a congenital eye malformation, resulting from a failure in optic fissure closure (OFC) and causing visual impairment. There has been little study of the epithelial fusion process underlying closure in the human embryo and coloboma aetiology remains poorly understood. We performed RNAseq of cell populations isolated using laser capture microdissection to identify novel human OFC signature genes and probe the expression profile of known coloboma genes, along with a comparative murine analysis. Gene set enrichment patterns showed conservation between species. Expression of genes involved in epithelial-to-mesenchymal transition was transiently enriched in the human fissure margins during OFC at days 41-44. Electron microscopy and histological analyses showed that cells transiently delaminate at the point of closure, and produce cytoplasmic protrusions, before rearranging to form two continuous epithelial layers. Apoptosis was not observed in the human fissure margins. These analyses support a model of human OFC in which epithelial cells at the fissure margins undergo a transient epithelial-to-mesenchymal-like transition, facilitating cell rearrangement to form a complete optic cup.
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Affiliation(s)
- Aara Patel
- UCL Great Ormond Street Institute of Child Health, and NIHR Great Ormond Street Hospital Biomedical Research Centre, University College London, London WC1N 1EH, UK
| | - Glenn Anderson
- Department of Histopathology, Great Ormond Street Hospital for Children NHS Foundation Trust, London WC1N 3JH, UK
| | - Gabriel L Galea
- UCL Great Ormond Street Institute of Child Health, and NIHR Great Ormond Street Hospital Biomedical Research Centre, University College London, London WC1N 1EH, UK
| | - Monika Balys
- Department of Histopathology, Great Ormond Street Hospital for Children NHS Foundation Trust, London WC1N 3JH, UK
| | - Jane C Sowden
- UCL Great Ormond Street Institute of Child Health, and NIHR Great Ormond Street Hospital Biomedical Research Centre, University College London, London WC1N 1EH, UK
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20
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Kodeboyina SK, Lee TJ, Churchwell L, Ulrich L, Bollinger K, Bogorad D, Estes A, Zhi W, Sharma S, Sharma A. The Constitutive Proteome of Human Aqueous Humor and Race Specific Alterations. Proteomes 2020; 8:proteomes8040034. [PMID: 33217969 PMCID: PMC7709111 DOI: 10.3390/proteomes8040034] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/15/2020] [Revised: 11/11/2020] [Accepted: 11/13/2020] [Indexed: 12/29/2022] Open
Abstract
Aqueous humor (AH) is the fluid in the anterior and posterior chambers of the eye that contains proteins regulating ocular homeostasis. Analysis of aqueous humor proteome is challenging, mainly due to low sample volume and protein concentration. In this study, by utilizing state of the art technology, we performed Liquid-Chromatography Mass spectrometry (LC-MS/MS) analysis of 88 aqueous humor samples from subjects undergoing cataract surgery. A total of 2263 unique proteins were identified, which were sub-divided into four categories that were based on their detection in the number of samples: High (n = 152), Medium (n = 91), Low (n = 128), and Rare (n = 1892). A total of 243 proteins detected in at least 50% of the samples were considered as the constitutive proteome of human aqueous humor. The biological processes and pathways enriched in the AH proteins mainly include vesicle mediated transport, acute phase response signaling, LXR/RXR activation, complement system, and secretion. The enriched molecular functions are endopeptidase activity, and various binding functions, such as protein binding, lipid binding, and ion binding. Additionally, this study provides a novel insight into race specific differences in the AH proteome. A total of six proteins were upregulated, and five proteins were downregulated in African American subjects as compared to Caucasians.
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Affiliation(s)
- Sai Karthik Kodeboyina
- Center for Biotechnology and Genomic Medicine, Augusta University, Augusta, GA 30912, USA; (S.K.K.); (T.J.L.); (L.C.); (W.Z.); (S.S.)
| | - Tae Jin Lee
- Center for Biotechnology and Genomic Medicine, Augusta University, Augusta, GA 30912, USA; (S.K.K.); (T.J.L.); (L.C.); (W.Z.); (S.S.)
| | - Lara Churchwell
- Center for Biotechnology and Genomic Medicine, Augusta University, Augusta, GA 30912, USA; (S.K.K.); (T.J.L.); (L.C.); (W.Z.); (S.S.)
| | - Lane Ulrich
- Department of Ophthalmology, Augusta University, Augusta, GA 30912, USA; (L.U.); (K.B.); (D.B.); (A.E.)
| | - Kathryn Bollinger
- Department of Ophthalmology, Augusta University, Augusta, GA 30912, USA; (L.U.); (K.B.); (D.B.); (A.E.)
| | - David Bogorad
- Department of Ophthalmology, Augusta University, Augusta, GA 30912, USA; (L.U.); (K.B.); (D.B.); (A.E.)
| | - Amy Estes
- Department of Ophthalmology, Augusta University, Augusta, GA 30912, USA; (L.U.); (K.B.); (D.B.); (A.E.)
| | - Wenbo Zhi
- Center for Biotechnology and Genomic Medicine, Augusta University, Augusta, GA 30912, USA; (S.K.K.); (T.J.L.); (L.C.); (W.Z.); (S.S.)
| | - Shruti Sharma
- Center for Biotechnology and Genomic Medicine, Augusta University, Augusta, GA 30912, USA; (S.K.K.); (T.J.L.); (L.C.); (W.Z.); (S.S.)
- Department of Ophthalmology, Augusta University, Augusta, GA 30912, USA; (L.U.); (K.B.); (D.B.); (A.E.)
| | - Ashok Sharma
- Center for Biotechnology and Genomic Medicine, Augusta University, Augusta, GA 30912, USA; (S.K.K.); (T.J.L.); (L.C.); (W.Z.); (S.S.)
- Department of Ophthalmology, Augusta University, Augusta, GA 30912, USA; (L.U.); (K.B.); (D.B.); (A.E.)
- Department of Population Health Sciences, Augusta University, Augusta, GA 30912, USA
- Correspondence:
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21
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Sun N, Dou X, Tang Z, Zhang D, Ni N, Wang J, Gao H, Ju Y, Dai X, Zhao C, Gu P, Ji J, Feng C. Bio-inspired chiral self-assemblies promoted neuronal differentiation of retinal progenitor cells through activation of metabolic pathway. Bioact Mater 2020; 6:990-997. [PMID: 33102941 PMCID: PMC7560590 DOI: 10.1016/j.bioactmat.2020.09.027] [Citation(s) in RCA: 19] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/27/2020] [Revised: 09/22/2020] [Accepted: 09/27/2020] [Indexed: 12/30/2022] Open
Abstract
Retinal degeneration is a main class of ocular diseases. So far, retinal progenitor cell (RPC) transplantation has been the most potential therapy for it, in which promoting RPCs neuronal differentiation remains an unmet challenge. To address this issue, innovatively designed L/ d - phenylalanine based chiral nanofibers (LPG and DPG) are employed and it finds that chirality of fibers can efficiently regulate RPCs differentiation. qPCR, western blot, and immunofluorescence analysis show that right-handed helical DPG nanofibers significantly promote RPCs neuronal differentiation, whereas left-handed LPG nanofibers decrease this effect. These effects are mainly ascribed to the stereoselective interaction between chiral helical nanofibers and retinol-binding protein 4 (RBP4, a key protein in the retinoic acid (RA) metabolic pathway). The findings of chirality-dependent neuronal differentiation provide new strategies for treatment of neurodegenerative diseases via optimizing differentiation of transplanted stem cells on chiral nanofibers.
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Affiliation(s)
- Na Sun
- Shanghai Key Laboratory of Orbital Diseases and Ocular Oncology, Department of Ophthalmology, Ninth People's Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai, 200011, China
| | - Xiaoqiu Dou
- State Key Lab of Metal Matrix Composites, School of Materials Science and Engineering, Shanghai Jiaotong University, Dongchuan Road 800, 200240, Shanghai, China
| | - Zhimin Tang
- Shanghai Key Laboratory of Orbital Diseases and Ocular Oncology, Department of Ophthalmology, Ninth People's Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai, 200011, China
| | - Dandan Zhang
- Shanghai Key Laboratory of Orbital Diseases and Ocular Oncology, Department of Ophthalmology, Ninth People's Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai, 200011, China
| | - Ni Ni
- Shanghai Key Laboratory of Orbital Diseases and Ocular Oncology, Department of Ophthalmology, Ninth People's Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai, 200011, China
| | - Jiajing Wang
- Shanghai Key Laboratory of Orbital Diseases and Ocular Oncology, Department of Ophthalmology, Ninth People's Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai, 200011, China
| | - Huiqin Gao
- Shanghai Key Laboratory of Orbital Diseases and Ocular Oncology, Department of Ophthalmology, Ninth People's Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai, 200011, China
| | - Yahan Ju
- Shanghai Key Laboratory of Orbital Diseases and Ocular Oncology, Department of Ophthalmology, Ninth People's Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai, 200011, China
| | - Xiaochan Dai
- Shanghai Key Laboratory of Orbital Diseases and Ocular Oncology, Department of Ophthalmology, Ninth People's Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai, 200011, China
| | - Changli Zhao
- State Key Lab of Metal Matrix Composites, School of Materials Science and Engineering, Shanghai Jiaotong University, Dongchuan Road 800, 200240, Shanghai, China
| | - Ping Gu
- Shanghai Key Laboratory of Orbital Diseases and Ocular Oncology, Department of Ophthalmology, Ninth People's Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai, 200011, China
| | - Jing Ji
- Shanghai Key Laboratory of Orbital Diseases and Ocular Oncology, Department of Ophthalmology, Ninth People's Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai, 200011, China
| | - Chuanliang Feng
- State Key Lab of Metal Matrix Composites, School of Materials Science and Engineering, Shanghai Jiaotong University, Dongchuan Road 800, 200240, Shanghai, China
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Hufnagel RB, Walter MA, Arno G. Introduction to the special issue on Ophthalmic Genetics: Vision in 2020. AMERICAN JOURNAL OF MEDICAL GENETICS PART C-SEMINARS IN MEDICAL GENETICS 2020; 184:535-537. [PMID: 32864823 DOI: 10.1002/ajmg.c.31841] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/03/2020] [Accepted: 08/11/2020] [Indexed: 11/05/2022]
Abstract
In this special issue of the American Journal of Medical Genetics, Part C, we explore the ever-expanding field of Ophthalmic Genetics. The eye is unique among organs for its accessibility to physical examination, permitting exploration of every tissue by slit lamp microscopy, ophthalmoscopy, and imaging including color and autofluorescent photography, ultrasound, optical coherence tomography (OCT), electrophysiology, and adaptive optics confocal and scanning laser ophthalmoscopy. This accessibility permits a variety of surgical and nonsurgical treatments, including the first FDA-approved gene therapy, voretigene neparvovec-rzyl for RPE65-associated Leber Congenital Amaurosis. In this issue, we sought to provide a survey highlighting how heritable ophthalmic disorders are recognizable and accessible to clinical geneticists as well as ophthalmologists.
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Affiliation(s)
- Robert B Hufnagel
- National Eye Institute, National Institutes of Health, Bethesda, Maryland, USA
| | - Michael A Walter
- Department of Medical Genetics, University of Alberta, Edmonton, Alberta, Canada
| | - Gavin Arno
- University College London Institute of Ophthalmology, London, UK.,Moorfields Eye Hospital, London, UK
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23
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Cehajic-Kapetanovic J, Jasani KM, Shanks M, Clouston P, MacLaren RE. A novel homozygous c.67C>T variant in retinol binding protein 4 (RBP4) associated with retinitis pigmentosa and childhood acne vulgaris. Ophthalmic Genet 2020; 41:288-292. [PMID: 32323592 DOI: 10.1080/13816810.2020.1755985] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/25/2023]
Abstract
BACKGROUND The retinol binding protein 4 (RBP4) is essential in delivering retinol to the retinal pigment epithelium and normal functioning of the visual cycle. Homozygous mutations in the RBP4 gene lead to severe retinitis pigmentosa that is phenotypically indistinguishable from retinitis pigmentosa caused by other recessive mutations. METHODS Case Report. PURPOSE To report a novel homozygous RBP4 c.67 C > T variant in a case of retinitis pigmentosa associated with severe childhood acne vulgaris. RESULTS A 49-year old Caucasian man with a family history of retinitis pigmentosa, presented with low vision and night blindness from early childhood. Fundus examination showed findings typical of recessive retinitis pigmentosa. Next generation sequencing analysis revealed a novel homozygous RBP4 c.67 C > T variant. Examination of patient's back showed widespread scaring and hyperpigmentation secondary to severe childhood-onset acne vulgaris. Patient's affected brother, positive for the same homozygous variant, also had a history of severe acne vulgaris whereas the unaffected brother did not, confirming that mutations in RBP4 segregated with the acne vulgaris phenotype in this family. CONCLUSIONS We describe a case of retinitis pigmentosa associated with acne vulgaris and highlight the role of this systemic manifestation of retinol deficiency in confirming pathogenicity of the novel variant. Given the small size of the genomic RBP4 DNA (0.6kb), gene therapy using an adeno-associated viral vector with subretinal delivery has great potential to treat this severe childhood-onset blinding retinal disease. In addition, ubiquitous expression of RBP4 supports the development of in vitro functional assays to test the vector potency for clinical use.
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Affiliation(s)
- J Cehajic-Kapetanovic
- Oxford Eye Hospital, Oxford University Hospitals NHS Foundation Trust , Oxford, UK
- Nuffield Laboratory of Ophthalmology, Department of Clinical Neurosciences, Oxford University , Oxford, UK
| | - K M Jasani
- Oxford Eye Hospital, Oxford University Hospitals NHS Foundation Trust , Oxford, UK
| | - M Shanks
- Genetics Laboratories, Churchill Hospital, Oxford University Hospitals NHS Foundation Trust , Oxford, UK
| | - P Clouston
- Genetics Laboratories, Churchill Hospital, Oxford University Hospitals NHS Foundation Trust , Oxford, UK
| | - R E MacLaren
- Oxford Eye Hospital, Oxford University Hospitals NHS Foundation Trust , Oxford, UK
- Nuffield Laboratory of Ophthalmology, Department of Clinical Neurosciences, Oxford University , Oxford, UK
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von Lintig J, Moon J, Babino D. Molecular components affecting ocular carotenoid and retinoid homeostasis. Prog Retin Eye Res 2020; 80:100864. [PMID: 32339666 DOI: 10.1016/j.preteyeres.2020.100864] [Citation(s) in RCA: 30] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/25/2020] [Revised: 04/13/2020] [Accepted: 04/17/2020] [Indexed: 12/15/2022]
Abstract
The photochemistry of vision employs opsins and geometric isomerization of their covalently bound retinylidine chromophores. In different animal classes, these light receptors associate with distinct G proteins that either hyperpolarize or depolarize photoreceptor membranes. Vertebrates also use the acidic form of chromophore, retinoic acid, as the ligand of nuclear hormone receptors that orchestrate eye development. To establish and sustain these processes, animals must acquire carotenoids from the diet, transport them, and metabolize them to chromophore and retinoic acid. The understanding of carotenoid metabolism, however, lagged behind our knowledge about the biology of their receptor molecules. In the past decades, much progress has been made in identifying the genes encoding proteins that mediate the transport and enzymatic transformations of carotenoids and their retinoid metabolites. Comparative analysis in different animal classes revealed how evolutionary tinkering with a limited number of genes evolved different biochemical strategies to supply photoreceptors with chromophore. Mutations in these genes impair carotenoid metabolism and induce various ocular pathologies. This review summarizes this advancement and introduces the involved proteins, including the homeostatic regulation of their activities.
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Affiliation(s)
- Johannes von Lintig
- Department of Pharmacology, School of Medicine, Case Western Reserve University, Cleveland, OH, USA.
| | - Jean Moon
- Department of Pharmacology, School of Medicine, Case Western Reserve University, Cleveland, OH, USA
| | - Darwin Babino
- Department of Ophthalmology, School of Medicine, University of Washington, Seattle, WA, USA
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25
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Regulatory mechanism for the transmembrane receptor that mediates bidirectional vitamin A transport. Proc Natl Acad Sci U S A 2020; 117:9857-9864. [PMID: 32300017 DOI: 10.1073/pnas.1918540117] [Citation(s) in RCA: 20] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Vitamin A has diverse biological functions and is essential for human survival at every point from embryogenesis to adulthood. Vitamin A and its derivatives have been used to treat human diseases including vision diseases, skin diseases, and cancer. Both insufficient and excessive vitamin A uptake are detrimental, but how its transport is regulated is poorly understood. STRA6 is a multitransmembrane domain cell-surface receptor and mediates vitamin A uptake from plasma retinol binding protein (RBP). STRA6 can mediate both cellular vitamin A influx and efflux, but what regulates these opposing activities is unknown. To answer this question, we purified and identified STRA6-associated proteins in a native mammalian cell type that takes up vitamin A through STRA6 using mass spectrometry. We found that the major protein repeatedly identified as STRA6-associated protein is calmodulin, consistent with the cryogenic electron microscopy (cryo-EM) study of zebrafish STRA6 associated with calmodulin. Using radioactivity-based, high-performance liquid chromatography (HPLC)-based and real-time fluorescence techniques, we found that calmodulin profoundly affects STRA6's vitamin A transport activity. Increased calcium/calmodulin promotes cellular vitamin A efflux and suppresses vitamin A influx through STRA6. Further mechanistic studies revealed that calmodulin enhances the binding of apo-RBP to STRA6, and this enhancement is much more pronounced for apo-RBP than holo-RBP. This study revealed that calmodulin regulates STRA6's vitamin A influx or efflux activity by modulating its preferential interaction with apo-RBP or holo-RBP. This molecular mechanism of regulating vitamin A transport may point to new directions to treat human diseases associated with insufficient or excessive vitamin A uptake.
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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: 17] [Impact Index Per Article: 4.3] [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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Sirbu IO, Chiş AR, Moise AR. Role of carotenoids and retinoids during heart development. Biochim Biophys Acta Mol Cell Biol Lipids 2020; 1865:158636. [PMID: 31978553 DOI: 10.1016/j.bbalip.2020.158636] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/03/2019] [Revised: 01/15/2020] [Accepted: 01/16/2020] [Indexed: 02/08/2023]
Abstract
The nutritional requirements of the developing embryo are complex. In the case of dietary vitamin A (retinol, retinyl esters and provitamin A carotenoids), maternal derived nutrients serve as precursors to signaling molecules such as retinoic acid, which is required for embryonic patterning and organogenesis. Despite variations in the composition and levels of maternal vitamin A, embryonic tissues need to generate a precise amount of retinoic acid to avoid congenital malformations. Here, we summarize recent findings regarding the role and metabolism of vitamin A during heart development and we survey the association of genes known to affect retinoid metabolism or signaling with various inherited disorders. A better understanding of the roles of vitamin A in the heart and of the factors that affect retinoid metabolism and signaling can help design strategies to meet nutritional needs and to prevent birth defects and disorders associated with altered retinoid metabolism. This article is part of a Special Issue entitled Carotenoids recent advances in cell and molecular biology edited by Johannes von Lintig and Loredana Quadro.
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Affiliation(s)
- Ioan Ovidiu Sirbu
- Biochemistry Department, Victor Babes University of Medicine and Pharmacy, Eftimie Murgu Nr. 2, 300041 Timisoara, Romania; Timisoara Institute of Complex Systems, V. Lucaciu 18, 300044 Timisoara, Romania.
| | - Aimée Rodica Chiş
- Biochemistry Department, Victor Babes University of Medicine and Pharmacy, Eftimie Murgu Nr. 2, 300041 Timisoara, Romania
| | - Alexander Radu Moise
- Medical Sciences Division, Northern Ontario School of Medicine, Sudbury, ON P3E 2C6, Canada; Department of Chemistry and Biochemistry, Biology and Biomolecular Sciences Program, Laurentian University, Sudbury, ON P3E 2C6, Canada.
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Thompson B, Katsanis N, Apostolopoulos N, Thompson DC, Nebert DW, Vasiliou V. Genetics and functions of the retinoic acid pathway, with special emphasis on the eye. Hum Genomics 2019; 13:61. [PMID: 31796115 PMCID: PMC6892198 DOI: 10.1186/s40246-019-0248-9] [Citation(s) in RCA: 22] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/24/2019] [Accepted: 11/12/2019] [Indexed: 02/07/2023] Open
Abstract
Retinoic acid (RA) is a potent morphogen required for embryonic development. RA is formed in a multistep process from vitamin A (retinol); RA acts in a paracrine fashion to shape the developing eye and is essential for normal optic vesicle and anterior segment formation. Perturbation in RA-signaling can result in severe ocular developmental diseases—including microphthalmia, anophthalmia, and coloboma. RA-signaling is also essential for embryonic development and life, as indicated by the significant consequences of mutations in genes involved in RA-signaling. The requirement of RA-signaling for normal development is further supported by the manifestation of severe pathologies in animal models of RA deficiency—such as ventral lens rotation, failure of optic cup formation, and embryonic and postnatal lethality. In this review, we summarize RA-signaling, recent advances in our understanding of this pathway in eye development, and the requirement of RA-signaling for embryonic development (e.g., organogenesis and limb bud development) and life.
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Affiliation(s)
- Brian Thompson
- Department of Environmental Health Sciences, Yale School of Public Health, 60 College St, New Haven, CT, 06520, USA
| | - Nicholas Katsanis
- Stanley Manne Research Institute, Lurie Children's Hospital, Chicago, IL, 60611, USA.,Departments of Pediatrics, Northwestern University Feinberg School of Medicine, Chicago, IL, 60611, USA
| | - Nicholas Apostolopoulos
- Department of Environmental Health Sciences, Yale School of Public Health, 60 College St, New Haven, CT, 06520, USA
| | - David C Thompson
- Department of Clinical Pharmacy, Skaggs School of Pharmacy and Pharmaceutical Sciences, University of Colorado Denver, Aurora, CO, 80045, USA
| | - Daniel W Nebert
- Department of Environmental Health and Center for Environmental Genetics, University Cincinnati Medical Center, Cincinnati, OH, 45267-0056, USA
| | - Vasilis Vasiliou
- Department of Environmental Health Sciences, Yale School of Public Health, 60 College St, New Haven, CT, 06520, USA.
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29
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Carotenoid metabolism at the intestinal barrier. Biochim Biophys Acta Mol Cell Biol Lipids 2019; 1865:158580. [PMID: 31794861 DOI: 10.1016/j.bbalip.2019.158580] [Citation(s) in RCA: 47] [Impact Index Per Article: 9.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/23/2019] [Revised: 11/20/2019] [Accepted: 11/21/2019] [Indexed: 12/17/2022]
Abstract
Carotenoids exert a rich variety of physiological functions in mammals and are beneficial for human health. These lipids are acquired from the diet and metabolized to apocarotenoids, including retinoids (vitamin A and its metabolites). The small intestine is a major site for their absorption and bioconversion. From here, carotenoids and their metabolites are distributed within the body in triacylglycerol-rich lipoproteins to support retinoid signaling in peripheral tissues and photoreceptor function in the eyes. In recent years, much progress has been made in identifying carotenoid metabolizing enzymes, transporters, and binding proteins. A diet-responsive regulatory network controls the activity of these components and adapts carotenoid absorption and bioconversion to the bodily requirements of these lipids. Genetic variability in the genes encoding these components alters carotenoid homeostasis and is associated with pathologies. We here summarize the advanced state of knowledge about intestinal carotenoid metabolism and its impact on carotenoid and retinoid homeostasis of other organ systems, including the eyes, liver, and immune system. The implication of the findings for science-based intake recommendations for these essential dietary lipids is discussed. This article is part of a Special Issue entitled Carotenoids recent advances in cell and molecular biology edited by Johannes von Lintig and Loredana Quadro.
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Widjaja-Adhi MAK, Golczak M. The molecular aspects of absorption and metabolism of carotenoids and retinoids in vertebrates. Biochim Biophys Acta Mol Cell Biol Lipids 2019; 1865:158571. [PMID: 31770587 DOI: 10.1016/j.bbalip.2019.158571] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/08/2019] [Revised: 11/04/2019] [Accepted: 11/07/2019] [Indexed: 02/08/2023]
Abstract
Vitamin A is an essential nutrient necessary for numerous basic physiological functions, including reproduction and development, immune cell differentiation and communication, as well as the perception of light. To evade the dire consequences of vitamin A deficiency, vertebrates have evolved specialized metabolic pathways that enable the absorption, transport, and storage of vitamin A acquired from dietary sources as preformed retinoids or provitamin A carotenoids. This evolutionary advantage requires a complex interplay between numerous specialized retinoid-transport proteins, receptors, and enzymes. Recent advances in molecular and structural biology resulted in a rapid expansion of our understanding of these processes at the molecular level. This progress opened new avenues for the therapeutic manipulation of retinoid homeostasis. In this review, we summarize current research related to the biochemistry of carotenoid and retinoid-processing proteins with special emphasis on the structural aspects of their physiological actions. This article is part of a Special Issue entitled Carotenoids recent advances in cell and molecular biology edited by Johannes von Lintig and Loredana Quadro.
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Affiliation(s)
- Made Airanthi K Widjaja-Adhi
- Department of Pharmacology, School of Medicine, Case Western Reserve University, Cleveland, OH, United States of America
| | - Marcin Golczak
- Department of Pharmacology, School of Medicine, Case Western Reserve University, Cleveland, OH, United States of America; Cleveland Center for Membrane and Structural Biology, School of Medicine, Case Western Reserve University, Cleveland, OH, United States of America.
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Kaukonen M, Woods S, Ahonen S, Lemberg S, Hellman M, Hytönen MK, Permi P, Glaser T, Lohi H. Maternal Inheritance of a Recessive RBP4 Defect in Canine Congenital Eye Disease. Cell Rep 2019; 23:2643-2652. [PMID: 29847795 PMCID: PMC6546432 DOI: 10.1016/j.celrep.2018.04.118] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/09/2017] [Revised: 04/16/2018] [Accepted: 04/26/2018] [Indexed: 01/20/2023] Open
Abstract
Maternally skewed transmission of traits has been associated with genomic imprinting and oocyte-derived mRNA. We report canine congenital eye malformations, caused by an amino acid deletion (K12del) near the N terminus of retinol-binding protein (RBP4). The disease is only expressed when both dam and offspring are deletion homozygotes. RBP carries vitamin A (retinol) from hepatic stores to peripheral tissues, including the placenta and developing eye, where it is required to synthesize retinoic acid. Gestational vitamin A deficiency is a known risk factor for ocular birth defects. The K12del mutation disrupts RBP folding in vivo, decreasing its secretion from hepatocytes to serum. The maternal penetrance effect arises from an impairment in the sequential transfer of retinol across the placenta, via RBP encoded by maternal and fetal genomes. Our results demonstrate a mode of recessive maternal inheritance, with a physiological basis, and they extend previous observations on dominant-negative RBP4 alleles in humans.
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Affiliation(s)
- Maria Kaukonen
- Department of Veterinary Biosciences, University of Helsinki, 00014 Helsinki, Finland; Research Programs Unit, Molecular Neurology, University of Helsinki, 00014 Helsinki, Finland; The Folkhälsan Institute of Genetics, 00290 Helsinki, Finland
| | - Sean Woods
- Department of Cell Biology and Human Anatomy, University of California, Davis School of Medicine, Davis, CA 95616, USA
| | - Saija Ahonen
- Department of Veterinary Biosciences, University of Helsinki, 00014 Helsinki, Finland; Research Programs Unit, Molecular Neurology, University of Helsinki, 00014 Helsinki, Finland; The Folkhälsan Institute of Genetics, 00290 Helsinki, Finland
| | - Seppo Lemberg
- Department of Eye Diseases, Helsinki University Hospital, 00029 The Hospital District of Helsinki and Uusimaa, Finland
| | - Maarit Hellman
- Department of Chemistry, Nanoscience Center, University of Jyväskylä, 40014 Jyväskylä, Finland
| | - Marjo K Hytönen
- Department of Veterinary Biosciences, University of Helsinki, 00014 Helsinki, Finland; Research Programs Unit, Molecular Neurology, University of Helsinki, 00014 Helsinki, Finland; The Folkhälsan Institute of Genetics, 00290 Helsinki, Finland
| | - Perttu Permi
- Department of Chemistry, Nanoscience Center, University of Jyväskylä, 40014 Jyväskylä, Finland; Department of Biological and Environmental Science, Nanoscience Center, University of Jyväskylä, 40014 Jyväskylä, Finland
| | - Tom Glaser
- Department of Cell Biology and Human Anatomy, University of California, Davis School of Medicine, Davis, CA 95616, USA.
| | - Hannes Lohi
- Department of Veterinary Biosciences, University of Helsinki, 00014 Helsinki, Finland; Research Programs Unit, Molecular Neurology, University of Helsinki, 00014 Helsinki, Finland; The Folkhälsan Institute of Genetics, 00290 Helsinki, Finland.
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32
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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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33
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Nedelec B, Rozet JM, Fares Taie L. Genetic architecture of retinoic-acid signaling-associated ocular developmental defects. Hum Genet 2019; 138:937-955. [DOI: 10.1007/s00439-019-02052-2] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/09/2019] [Accepted: 07/23/2019] [Indexed: 12/14/2022]
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Wang S, Moise AR. Recent insights on the role and regulation of retinoic acid signaling during epicardial development. Genesis 2019; 57:e23303. [PMID: 31066193 PMCID: PMC6682438 DOI: 10.1002/dvg.23303] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/11/2019] [Revised: 04/23/2019] [Accepted: 04/24/2019] [Indexed: 12/18/2022]
Abstract
The vitamin A metabolite, retinoic acid, carries out essential and conserved roles in vertebrate heart development. Retinoic acid signals via retinoic acid receptors (RAR)/retinoid X receptors (RXRs) heterodimers to induce the expression of genes that control cell fate specification, proliferation, and differentiation. Alterations in retinoic acid levels are often associated with congenital heart defects. Therefore, embryonic levels of retinoic acid need to be carefully regulated through the activity of enzymes, binding proteins and transporters involved in vitamin A metabolism. Here, we review evidence of the complex mechanisms that control the fetal uptake and synthesis of retinoic acid from vitamin A precursors. Next, we highlight recent evidence of the role of retinoic acid in orchestrating myocardial compact zone growth and coronary vascular development.
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Affiliation(s)
- Suya Wang
- Department of Cardiology, Boston Children's Hospital, 300 Longwood Avenue, Boston, MA, 02115, USA
| | - Alexander R. Moise
- Medical Sciences Division, Northern Ontario School of Medicine, Sudbury, ON P3E 2C6, Canada
- Departments of Chemistry and Biochemistry, and Biology and Biomolecular Sciences Program, Laurentian University, Sudbury, ON, P3E 2C6 Canada
- Department of Pharmacology and Toxicology, School of Pharmacy, University of Kansas, Lawrence, KS, 66045, USA
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The Oculome Panel Test: Next-Generation Sequencing to Diagnose a Diverse Range of Genetic Developmental Eye Disorders. Ophthalmology 2019; 126:888-907. [PMID: 30653986 DOI: 10.1016/j.ophtha.2018.12.050] [Citation(s) in RCA: 55] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/03/2018] [Revised: 12/18/2018] [Accepted: 12/21/2018] [Indexed: 01/09/2023] Open
Abstract
PURPOSE To develop a comprehensive next-generation sequencing panel assay that screens genes known to cause developmental eye disorders and inherited eye disease and to evaluate its diagnostic yield in a pediatric cohort with malformations of the globe, anterior segment anomalies, childhood glaucoma, or a combination thereof. DESIGN Evaluation of diagnostic test. PARTICIPANTS Two hundred seventy-seven children, 0 to 16 years of age, diagnosed with nonsyndromic or syndromic developmental eye defects without a genetic diagnosis. METHODS We developed a new oculome panel using a custom-designed Agilent SureSelect QXT target capture method (Agilent Technologies, Santa Clara, CA) to capture and perform parallel high-throughput sequencing analysis of 429 genes associated with eye disorders. Bidirectional Sanger sequencing confirmed suspected pathogenic variants. MAIN OUTCOME MEASURES Collated clinical details and oculome molecular genetic results. RESULTS The oculome design covers 429 known eye disease genes; these are subdivided into 5 overlapping virtual subpanels for anterior segment developmental anomalies including glaucoma (ASDA; 59 genes), microphthalmia-anophthalmia-coloboma (MAC; 86 genes), congenital cataracts and lens-associated conditions (70 genes), retinal dystrophies (RET; 235 genes), and albinism (15 genes), as well as additional genes implicated in optic atrophy and complex strabismus (10 genes). Panel development and testing included analyzing 277 clinical samples and 3 positive control samples using Illumina sequencing platforms; more than 30× read depth was achieved for 99.5% of the targeted 1.77-Mb region. Bioinformatics analysis performed using a pipeline based on Freebayes and ExomeDepth to identify coding sequence and copy number variants, respectively, resulted in a definitive diagnosis in 68 of 277 samples, with variability in diagnostic yield between phenotypic subgroups: MAC, 8.2% (8 of 98 cases solved); ASDA, 24.8% (28 of 113 cases solved); other or syndromic, 37.5% (3 of 8 cases solved); RET, 42.8% (21 of 49 cases solved); and congenital cataracts and lens-associated conditions, 88.9% (8 of 9 cases solved). CONCLUSIONS The oculome test diagnoses a comprehensive range of genetic conditions affecting the development of the eye, potentially replacing protracted and costly multidisciplinary assessments and allowing for faster targeted management. The oculome enabled molecular diagnosis of a significant number of cases in our sample cohort of varied ocular birth defects.
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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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Silvaroli JA, Widjaja-Adhi MAK, Trischman T, Chelstowska S, Horwitz S, Banerjee S, Kiser PD, Blaner WS, Golczak M. Abnormal Cannabidiol Modulates Vitamin A Metabolism by Acting as a Competitive Inhibitor of CRBP1. ACS Chem Biol 2019; 14:434-448. [PMID: 30721022 DOI: 10.1021/acschembio.8b01070] [Citation(s) in RCA: 17] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023]
Abstract
Cellular retinol-binding proteins (CRBPs) facilitate the uptake and intracellular transport of vitamin A. They integrate retinoid metabolism, playing an important role in regulating the synthesis of bioactive vitamin A metabolites. Thus, CRBPs constitute potential pharmacological targets to modulate cellular retinoid status that in turn may have applications in the treatment of certain immunological, metabolic, and ocular disorders. Here we identify abnormal cannabidiol (abn-CBD) as a nonretinoid inhibitor of cellular retinol-binding protein 1 (CRBP1). X-ray crystal structures of CRBP1 in complex with abn-CBD and its derivatives revealed a distinctive mode of protein-ligand interaction and provided a molecular basis for the high affinity and selectivity of this compound. We demonstrated that abn-CBD modulates the flux of retinoids via the retinoid cycle in vivo. Furthermore, the biological activity of abn-CBD was evidenced by its ability to protect against light-induced retinal damage in Balb/cJ mice. Altogether, our findings indicate that targeting selected CRBPs with a small-molecule inhibitor can potentially lead to the development of new therapeutic agents to counteract diseases with etiologies involving imbalance in retinoid metabolism or signaling.
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Affiliation(s)
| | | | | | | | | | - Surajit Banerjee
- Department of Chemistry and Chemical Biology, Cornell University, Ithaca, NY, United States
- Northeastern Collaborative Access Team, Argonne National Laboratory, Argonne, IL, United States
| | - Philip D. Kiser
- Research Service, Louis Stokes Cleveland VA Medical Center, Cleveland, OH, United States
| | - William S. Blaner
- Department of Medicine, College of Physicians and Surgeons, Columbia University, New York, NY, United States
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Genetics of anophthalmia and microphthalmia. Part 1: Non-syndromic anophthalmia/microphthalmia. Hum Genet 2019; 138:799-830. [PMID: 30762128 DOI: 10.1007/s00439-019-01977-y] [Citation(s) in RCA: 50] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/19/2018] [Accepted: 01/30/2019] [Indexed: 12/22/2022]
Abstract
Eye formation is the result of coordinated induction and differentiation processes during embryogenesis. Disruption of any one of these events has the potential to cause ocular growth and structural defects, such as anophthalmia and microphthalmia (A/M). A/M can be isolated or occur with systemic anomalies, when they may form part of a recognizable syndrome. Their etiology includes genetic and environmental factors; several hundred genes involved in ocular development have been identified in humans or animal models. In humans, around 30 genes have been repeatedly implicated in A/M families, although many other genes have been described in single cases or families, and some genetic syndromes include eye anomalies occasionally as part of a wider phenotype. As a result of this broad genetic heterogeneity, with one or two notable exceptions, each gene explains only a small percentage of cases. Given the overlapping phenotypes, these genes can be most efficiently tested on panels or by whole exome/genome sequencing for the purposes of molecular diagnosis. However, despite whole exome/genome testing more than half of patients currently remain without a molecular diagnosis. The proportion of undiagnosed cases is even higher in those individuals with unilateral or milder phenotypes. Furthermore, even when a strong gene candidate is available for a patient, issues of incomplete penetrance and germinal mosaicism make diagnosis and genetic counseling challenging. In this review, we present the main genes implicated in non-syndromic human A/M phenotypes and, for practical purposes, classify them according to the most frequent or predominant phenotype each is associated with. Our intention is that this will allow clinicians to rank and prioritize their molecular analyses and interpretations according to the phenotypes of their patients.
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39
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Prospects and modalities for the treatment of genetic ocular anomalies. Hum Genet 2019; 138:1019-1026. [DOI: 10.1007/s00439-018-01968-5] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/03/2018] [Accepted: 12/24/2018] [Indexed: 12/13/2022]
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40
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Tarilonte M, Morín M, Ramos P, Galdós M, Blanco-Kelly F, Villaverde C, Rey-Zamora D, Rebolleda G, Muñoz-Negrete FJ, Tahsin-Swafiri S, Gener B, Moreno-Pelayo MA, Ayuso C, Villamar M, Corton M. Parental Mosaicism in PAX6 Causes Intra-Familial Variability: Implications for Genetic Counseling of Congenital Aniridia and Microphthalmia. Front Genet 2018; 9:479. [PMID: 30386378 PMCID: PMC6199369 DOI: 10.3389/fgene.2018.00479] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/10/2018] [Accepted: 09/26/2018] [Indexed: 11/17/2022] Open
Abstract
Mutations in PAX6 are involved in several developmental eye disorders. These disorders have considerable phenotypic variability, ranging from panocular forms of congenital aniridia and microphthalmia to isolated anomalies of the anterior or posterior segment. Here, we describe 3 families with variable inter-generational ocular expression of aniridia, iris coloboma, or microphthalmia, and an unusual transmission of PAX6 mutations from an unaffected or mildly affected parent; all of which raised suspicion of gonosomal mosaicism. We first identified two previously known nonsense mutations and one novel likely pathogenic missense variant in PAX6 in probands by means of targeted NGS. The subsequent segregation analysis by Sanger sequencing evidenced the presence of highly probable mosaic events in paternal blood samples. Mosaicism was further confirmed by droplet digital PCR analysis in several somatic tissues of mosaic fathers. Quantification of the mutant allele fraction in parental samples showed a marked deviation from 50%, with a range between 12 and 29% depending on cell type. Gonosomal mosaicsm was definitively confirmed in one of the families thanks to the availability of a sperm sample from the mosaic father. Thus, the recurrence risk in this family was estimated to be about one-third. This is the first report confirming parental PAX6 mosaicism as a cause of disease recurrence in aniridia and other related phenotypes. In addition, we demonstrated that post-zygotic mosaicism is a frequent and underestimated pathogenic mechanism in aniridia, explaining intra-familial phenotypic variability in many cases. Our findings may have substantial implications for genetic counseling in congenital aniridia. Thus, we also highlight the importance of comprehensive genetic screening of parents for new sporadic cases with aniridia or related developmental eye disease to more accurately assess recurrence risk. In conclusion, somatic and/or gonosomal mosaicism should be taken into consideration as a genetic factor to explain not only families with unaffected parents despite multiple affected children but also variable expressivity, apparent de novo cases, and even uncharacterized cases of aniridia and related developmental eye disorders, apparently lacking PAX6 mutations.
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Affiliation(s)
- María Tarilonte
- Department of Genetics and Genomics, Instituto de Investigación Sanitaria de la Fundación Jiménez Díaz, University Hospital - Universidad Autónoma de Madrid, Madrid, Spain
| | - Matías Morín
- Servicio de Genética, Instituto Ramón y Cajal de Investigación Sanitaria, Hospital Universitario Ramón y Cajal, Madrid, Spain.,Centre for Biomedical Network Research on Rare Diseases, Instituto de Salud Carlos III, Madrid, Spain
| | - Patricia Ramos
- Department of Genetics and Genomics, Instituto de Investigación Sanitaria de la Fundación Jiménez Díaz, University Hospital - Universidad Autónoma de Madrid, Madrid, Spain
| | - Marta Galdós
- Department of Ophthalmology, Cruces University Hospital, Bilbao, Spain
| | - Fiona Blanco-Kelly
- Department of Genetics and Genomics, Instituto de Investigación Sanitaria de la Fundación Jiménez Díaz, University Hospital - Universidad Autónoma de Madrid, Madrid, Spain.,Centre for Biomedical Network Research on Rare Diseases, Instituto de Salud Carlos III, Madrid, Spain
| | - Cristina Villaverde
- Department of Genetics and Genomics, Instituto de Investigación Sanitaria de la Fundación Jiménez Díaz, University Hospital - Universidad Autónoma de Madrid, Madrid, Spain.,Centre for Biomedical Network Research on Rare Diseases, Instituto de Salud Carlos III, Madrid, Spain
| | - Dolores Rey-Zamora
- Servicio de Genética, Instituto Ramón y Cajal de Investigación Sanitaria, Hospital Universitario Ramón y Cajal, Madrid, Spain
| | - Gema Rebolleda
- Department of Glaucoma, Instituto Ramón y Cajal de Investigación Sanitaria, Hospital Universitario Ramón y Cajal, Madrid, Spain
| | - Francisco J Muñoz-Negrete
- Department of Glaucoma, Instituto Ramón y Cajal de Investigación Sanitaria, Hospital Universitario Ramón y Cajal, Madrid, Spain
| | - Saoud Tahsin-Swafiri
- Department of Genetics and Genomics, Instituto de Investigación Sanitaria de la Fundación Jiménez Díaz, University Hospital - Universidad Autónoma de Madrid, Madrid, Spain.,Centre for Biomedical Network Research on Rare Diseases, Instituto de Salud Carlos III, Madrid, Spain
| | - Blanca Gener
- Centre for Biomedical Network Research on Rare Diseases, Instituto de Salud Carlos III, Madrid, Spain.,Department of Genetics, BioCruces Health Research Institute, Cruces University Hospital, Bilbao, Spain
| | - Miguel-Angel Moreno-Pelayo
- Servicio de Genética, Instituto Ramón y Cajal de Investigación Sanitaria, Hospital Universitario Ramón y Cajal, Madrid, Spain.,Centre for Biomedical Network Research on Rare Diseases, Instituto de Salud Carlos III, Madrid, Spain
| | - Carmen Ayuso
- Department of Genetics and Genomics, Instituto de Investigación Sanitaria de la Fundación Jiménez Díaz, University Hospital - Universidad Autónoma de Madrid, Madrid, Spain.,Centre for Biomedical Network Research on Rare Diseases, Instituto de Salud Carlos III, Madrid, Spain
| | - Manuela Villamar
- Servicio de Genética, Instituto Ramón y Cajal de Investigación Sanitaria, Hospital Universitario Ramón y Cajal, Madrid, Spain.,Centre for Biomedical Network Research on Rare Diseases, Instituto de Salud Carlos III, Madrid, Spain
| | - Marta Corton
- Department of Genetics and Genomics, Instituto de Investigación Sanitaria de la Fundación Jiménez Díaz, University Hospital - Universidad Autónoma de Madrid, Madrid, Spain.,Centre for Biomedical Network Research on Rare Diseases, Instituto de Salud Carlos III, Madrid, Spain
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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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Riera M, Wert A, Nieto I, Pomares E. Panel-based whole exome sequencing identifies novel mutations in microphthalmia and anophthalmia patients showing complex Mendelian inheritance patterns. Mol Genet Genomic Med 2017; 5:709-719. [PMID: 29178648 PMCID: PMC5702572 DOI: 10.1002/mgg3.329] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/31/2017] [Revised: 07/21/2017] [Accepted: 07/27/2017] [Indexed: 12/15/2022] Open
Abstract
Background Microphthalmia and anophthalmia (MA) are congenital eye abnormalities that show an extremely high clinical and genetic complexity. In this study, we evaluated the implementation of whole exome sequencing (WES) for the genetic analysis of MA patients. This approach was used to investigate three unrelated families in which previous single‐gene analyses failed to identify the molecular cause. Methods A total of 47 genes previously associated with nonsyndromic MA were included in our panel. WES was performed in one affected patient from each family using the AmpliSeqTM Exome technology and the Ion ProtonTM platform. Results A novel heterozygous OTX2 missense mutation was identified in a patient showing bilateral anophthalmia who inherited the variant from a parent who was a carrier, but showed no sign of the condition. We also describe a new PAX6 missense variant in an autosomal‐dominant pedigree affected by mild bilateral microphthalmia showing high intrafamiliar variability, with germline mosaicism determined to be the most plausible molecular cause of the disease. Finally, a heterozygous missense mutation in RBP4 was found to be responsible in an isolated case of bilateral complex microphthalmia. Conclusion This study highlights that panel‐based WES is a reliable and effective strategy for the genetic diagnosis of MA. Furthermore, using this technique, the mutational spectrum of these diseases was broadened, with novel variants identified in each of the OTX2,PAX6, and RBP4 genes. Moreover, we report new cases of reduced penetrance, mosaicism, and variable phenotypic expressivity associated with MA, further demonstrating the heterogeneity of such disorders.
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Affiliation(s)
- Marina Riera
- Departament de Genètica, Institut de Microcirurgia Ocular (IMO), Barcelona, Spain
| | - Ana Wert
- Departament d'Oftalmologia Pediàtrica, Estrabisme i Neuroftalmologia, Institut de Microcirurgia Ocular (IMO), Barcelona, Spain
| | - Isabel Nieto
- Departament de Còrnia, Cataracta i Cirurgia Refractiva, Institut de Microcirurgia Ocular (IMO), Barcelona, Spain
| | - Esther Pomares
- Departament de Genètica, Institut de Microcirurgia Ocular (IMO), Barcelona, Spain
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Pu P, Stone CE, Burdick JT, Murray JI, Sundaram MV. The Lipocalin LPR-1 Cooperates with LIN-3/EGF Signaling To Maintain Narrow Tube Integrity in Caenorhabditis elegans. Genetics 2017; 205:1247-1260. [PMID: 28040739 PMCID: PMC5340336 DOI: 10.1534/genetics.116.195156] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/23/2016] [Accepted: 12/21/2016] [Indexed: 11/18/2022] Open
Abstract
Lipocalins are secreted cup-shaped glycoproteins that bind sterols, fatty acids, and other lipophilic molecules. Lipocalins have been implicated in a wide array of processes related to lipophilic cargo transport, sequestration, and signaling, and several are used as biomarkers for human disease, but the functions of most lipocalins remain poorly understood. Here we show that the Caenorhabditis elegans lipocalin LPR-1 is required to maintain apical membrane integrity and a continuous lumen in two narrow unicellular tubes, the excretory duct and pore, during a period of rapid lumen elongation. LPR-1 fusion protein is expressed by the duct and pore and accumulates both intracellularly and in apical extracellular compartments, but it can also function cell nonautonomously when provided from outside of the excretory system. lpr-1 mutant defects can be rescued by increased signaling through the epidermal growth factor (EGF)-Ras-extracellular signal regulated kinase (ERK) pathway, which promotes the more elongated duct vs. less elongated pore tube fate. Spatial and temporal rescue experiments indicate that Ras signaling acts within the duct and pore tubes during or prior to cell fate determination to bypass the requirement for LPR-1 lpr-1 mutations did not disrupt LIN-3/EGF-dependent duct-fate specification, prevent functioning of any specific LIN-3/EGF isoform, or alter LET-23/EGFR localization, and reduced signaling did not phenocopy or enhance lpr-1 mutant defects. These data suggest that LPR-1 protects lumen integrity through a LIN-3/EGF-independent mechanism, but that increased signaling upregulates some target(s) that can compensate for lpr-1 absence.
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Affiliation(s)
- Pu Pu
- Department of Genetics, Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania 19104
| | - Craig E Stone
- Department of Genetics, Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania 19104
| | - Joshua T Burdick
- Department of Genetics, Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania 19104
| | - John I Murray
- Department of Genetics, Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania 19104
| | - Meera V Sundaram
- Department of Genetics, Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania 19104
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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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Nilsson O, Isoherranen N, Guo MH, Lui JC, Jee YH, Guttmann-Bauman I, Acerini C, Lee W, Allikmets R, Yanovski JA, Dauber A, Baron J. Accelerated Skeletal Maturation in Disorders of Retinoic Acid Metabolism: A Case Report and Focused Review of the Literature. Horm Metab Res 2016; 48:737-744. [PMID: 27589347 PMCID: PMC5534175 DOI: 10.1055/s-0042-114038] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
Nutritional excess of vitamin A, a precursor for retinoic acid (RA), causes premature epiphyseal fusion, craniosynostosis, and light-dependent retinopathy. Similarly, homozygous loss-of-function mutations in CYP26B1, one of the major RA-metabolizing enzymes, cause advanced bone age, premature epiphyseal fusion, and craniosynostosis. In this paper, a patient with markedly accelerated skeletal and dental development, retinal scarring, and autism-spectrum disease is presented and the role of retinoic acid in longitudinal bone growth and skeletal maturation is reviewed. Genetic studies were carried out using SNP array and exome sequencing. RA isomers were measured in the patient, family members, and in 18 age-matched healthy children using high-performance liquid chromatography coupled to tandem mass spectrometry. A genomic SNP array identified a novel 8.3 megabase microdeletion on chromosome 10q23.2-23.33. The 79 deleted genes included CYP26A1 and C1, both major RA-metabolizing enzymes. Exome sequencing did not detect any variants that were predicted to be deleterious in the remaining alleles of these genes or other known retinoic acid-metabolizing enzymes. The patient exhibited elevated plasma total RA (16.5 vs. 12.6±1.5 nM, mean±SD, subject vs. controls) and 13-cisRA (10.7 nM vs. 6.1±1.1). The findings support the hypothesis that elevated RA concentrations accelerate bone and dental maturation in humans. CYP26A1 and C1 haploinsufficiency may contribute to the elevated retinoic acid concentrations and clinical findings of the patient, although this phenotype has not been reported in other patients with similar deletions, suggesting that other unknown genetic or environmental factors may also contribute.
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Affiliation(s)
- Ola Nilsson
- Eunice Kennedy Shriver National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, MD, USA
- Center for Molecular Medicine and Pediatric Endocrinology Unit, Department of Women’s and Children’s Health, Karolinska Institutet and Karolinska University Hospital, Stockholm, Sweden
| | - Nina Isoherranen
- Department of Pharmaceutics School of Pharmacy, University of Washington, Seattle, WA, USA
| | - Michael H. Guo
- Program in Biological and Biomedical Sciences, Harvard Medical School, Boston, MA, USA
- Department of Genetics, Harvard Medical School, Boston, MA, USA
- Program in Medical and Population Genetics, Broad Institute, Cambridge, MA, USA
| | - Julian C. Lui
- Eunice Kennedy Shriver National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, MD, USA
| | - Youn Hee Jee
- Eunice Kennedy Shriver National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, MD, USA
| | - Ines Guttmann-Bauman
- Harold Schnitzer Diabetes Health Center, Oregon Health and Science University, Portland, OR, USA
| | - Carlo Acerini
- Department of Paediatrics, University of Cambridge, Cambridge, UK
| | - Winston Lee
- Department of Ophthalmology, Columbia University, New York, NY, USA
| | - Rando Allikmets
- Department of Ophthalmology, Columbia University, New York, NY, USA
- Department of Pathology and Cell Biology, Columbia University, New York, NY, USA
| | - Jack A. Yanovski
- Eunice Kennedy Shriver National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, MD, USA
| | - Andrew Dauber
- Cincinnati Center for Growth Disorders, Division of Endocrinology, Cincinnati Children’s Hospital Medical Center, Cincinnati, OH, USA
| | - Jeffrey Baron
- Eunice Kennedy Shriver National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, MD, USA
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Abstract
Recent progress in molecular understanding of the retinoid cycle in mammalian retina stems from painstaking biochemical reconstitution studies supported by natural or engineered animal models with known genetic lesions and studies of humans with specific genetic blinding diseases. Structural and membrane biology have been used to detect critical retinal enzymes and proteins and their substrates and ligands, placing them in a cellular context. These studies have been supplemented by analytical chemistry methods that have identified small molecules by their spectral characteristics, often in conjunction with the evaluation of models of animal retinal disease. It is from this background that rational therapeutic interventions to correct genetic defects or environmental insults are identified. Thus, most presently accepted modulators of the retinoid cycle already have demonstrated promising results in animal models of retinal degeneration. These encouraging signs indicate that some human blinding diseases can be alleviated by pharmacological interventions.
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Affiliation(s)
- Philip D Kiser
- Department of Pharmacology, Cleveland Center for Membrane and Structural Biology, School of Medicine, Case Western Reserve University, Cleveland, Ohio 44106 ; Louis Stokes Cleveland VA Medical Center, Cleveland, Ohio 44106
| | - Krzysztof Palczewski
- Department of Pharmacology, Cleveland Center for Membrane and Structural Biology, School of Medicine, Case Western Reserve University, Cleveland, Ohio 44106
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Kelly M, Widjaja-Adhi MAK, Palczewski G, von Lintig J. Transport of vitamin A across blood-tissue barriers is facilitated by STRA6. FASEB J 2016; 30:2985-95. [PMID: 27189978 DOI: 10.1096/fj.201600446r] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/21/2016] [Accepted: 05/02/2016] [Indexed: 12/31/2022]
Abstract
Vitamin A bound to retinol binding protein 4 (RBP4) constitutes the major transport mode for retinoids in fasting circulation. Emerging evidence suggests that membrane protein, STRA6 (stimulated by retinoic acid 6), is the RBP4 receptor and vitamin A channel; however, the role of STRA6 in vitamin A homeostasis remains to be defined in vivo We subjected Stra6-knockout mice to diets sufficient and insufficient for vitamin A and used heterozygous siblings as controls. We determined vitamin A levels of the eyes, brain, and testis, which highly express Stra6, as well as of tissues with low expression, such as lung and fat. We also studied the consequence of STRA6 deficiency on retinoid-dependent processes in tissues. Furthermore, we examined how STRA6 deficiency affected retinoid homeostasis of the aging mouse. The picture that emerged indicates a critical role for STRA6 in the transport of vitamin A across blood-tissue barriers in the eyes, brain, and testis. Concurrently, fat and lung rely on dietary vitamin A. In testis and brain, Stra6 expression was regulated by vitamin A. In controls, this regulation reduced vitamin A consumption when the dietary supply was limited, sequestering it for the eye. Thus, STRA6 is critical for vitamin A homeostasis and the adaption of this process to the fluctuating supply of the vitamin.-Kelly, M., Widjaja-Adhi, M. A. K., Palczewski, G., von Lintig, J. Transport of vitamin A across blood-tissue barriers is facilitated by STRA6.
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Affiliation(s)
- Mary Kelly
- Department of Pharmacology, Case Western Reserve University School of Medicine, Cleveland, Ohio, USA
| | - M Airanthi K Widjaja-Adhi
- Department of Pharmacology, Case Western Reserve University School of Medicine, Cleveland, Ohio, USA
| | - Grzegorz Palczewski
- Department of Pharmacology, Case Western Reserve University School of Medicine, Cleveland, Ohio, USA
| | - Johannes von Lintig
- Department of Pharmacology, Case Western Reserve University School of Medicine, Cleveland, Ohio, USA
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Vitamin A Transport Mechanism of the Multitransmembrane Cell-Surface Receptor STRA6. MEMBRANES 2015; 5:425-53. [PMID: 26343735 PMCID: PMC4584289 DOI: 10.3390/membranes5030425] [Citation(s) in RCA: 45] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 06/27/2015] [Accepted: 08/24/2015] [Indexed: 12/18/2022]
Abstract
Vitamin A has biological functions as diverse as sensing light for vision, regulating stem cell differentiation, maintaining epithelial integrity, promoting immune competency, regulating learning and memory, and acting as a key developmental morphogen. Vitamin A derivatives have also been used in treating human diseases. If vitamin A is considered a drug that everyone needs to take to survive, evolution has come up with a natural drug delivery system that combines sustained release with precise and controlled delivery to the cells or tissues that depend on it. This "drug delivery system" is mediated by plasma retinol binding protein (RBP), the principle and specific vitamin A carrier protein in the blood, and STRA6, the cell-surface receptor for RBP that mediates cellular vitamin A uptake. The mechanism by which the RBP receptor absorbs vitamin A from the blood is distinct from other known cellular uptake mechanisms. This review summarizes recent progress in elucidating the fundamental molecular mechanism mediated by the RBP receptor and multiple newly discovered catalytic activities of this receptor, and compares this transport system with retinoid transport independent of RBP/STRA6. How to target this new type of transmembrane receptor using small molecules in treating diseases is also discussed.
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49
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Abstract
Chou et al. discover a new mode of maternal inheritance by analyzing human mutations in plasma retinol binding protein (RBP). Mechanistically, these mutations simultaneously lower RBP's affinity for vitamin A and greatly increase its affinity for its cell-surface receptor, thus dominantly blocking the transmembrane transport of vitamin A.
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Affiliation(s)
- Ming Zhong
- Howard Hughes Medical Institute, Department of Physiology and Jules Stein Eye Institute, David Geffen School of Medicine, University of California, Los Angeles, CA 90095, U.S.A
| | - Hui Sun
- Howard Hughes Medical Institute, Department of Physiology and Jules Stein Eye Institute, David Geffen School of Medicine, University of California, Los Angeles, CA 90095, U.S.A.
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