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Yu X, Zhang M, Zhao H, Gao Y, Deng L, Shi Y, Fan Z. Nanophthalmos-Associated MYRF gene mutation facilitates intraocular inflammation in mice. Int Immunopharmacol 2024; 137:112519. [PMID: 38901241 DOI: 10.1016/j.intimp.2024.112519] [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: 05/22/2024] [Accepted: 06/16/2024] [Indexed: 06/22/2024]
Abstract
PURPOSE Patients with nanophthalmos might be prone to developing intraocular inflammation following an acute glaucoma attack. Here, we aimed to investigate the role of MYRF in intraocular inflammation by modeling the mutation in mice. METHODS Nanophthalmos frameshift mutation of Myrf was introduced into the mouse genome with the CRISPR-Cas9 system. Signaling pathways in eye tissues were delineated using RNA sequencing and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway enrichment analysis. Intraocular inflammation was induced by a lipopolysaccharide (LPS) intravitreal injection. Dexamethasone (DEX) was administered systemically and locally a week before the LPS injection. The anterior segment clinical scores of the mice were examined 24 h after the LPS injection. Infiltrating inflammatory cells were evaluated with histopathology and immunofluorescence. The mRNA levels of inflammatory cytokines were quantified with reverse transcription-quantitative PCR (RT-qPCR) and the corresponding protein concentrations using enzyme-linked immunosorbent assay (ELISA). RESULTS Many inflammation-associated signaling pathways were enriched in Myrf mut/+ mice ocular tissues. Clinical scores of Myrf mut/+ mice were significantly higher than those of Myrf +/+ mice 24 h after LPS administration. Histological examination demonstrated high inflammatory cell infiltration in the anterior and vitreous chambers in Myrf mut/+ mice, with numerous CD45+ and CD11b+ inflammatory cells. Moreover, enhanced expression of inflammatory cytokines MCP-1, TGF-β, and IL-1β in eyes and aqueous humor of Myrf mut/+ mice was detected. Remarkably, pretreating Myrf mut/+ mice with DEX relieved the intraocular inflammation. CONCLUSION Nanophthalmos-associated MYRF mutation renders mouse eyes more susceptible to inflammation. Dexamethasone treatment ameliorates the inflammatory response.
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Affiliation(s)
- Xiaowei Yu
- Beijing Tongren Eye Center Research Ward, Beijing Tongren Hospital, Beijing Institute of Ophthalmology, Beijing Ophthalmology & Visual Sciences Key Laboratory, Capital Medical University, Beijing, 100730, China
| | - Miao Zhang
- Beijing Tongren Eye Center Research Ward, Beijing Tongren Hospital, Beijing Institute of Ophthalmology, Beijing Ophthalmology & Visual Sciences Key Laboratory, Capital Medical University, Beijing, 100730, China
| | - Hanxue Zhao
- Beijing Tongren Eye Center Research Ward, Beijing Tongren Hospital, Beijing Institute of Ophthalmology, Beijing Ophthalmology & Visual Sciences Key Laboratory, Capital Medical University, Beijing, 100730, China
| | - Yan Gao
- Beijing Tongren Eye Center Research Ward, Beijing Tongren Hospital, Beijing Institute of Ophthalmology, Beijing Ophthalmology & Visual Sciences Key Laboratory, Capital Medical University, Beijing, 100730, China
| | - Lin Deng
- Beijing Tongren Eye Center Research Ward, Beijing Tongren Hospital, Beijing Institute of Ophthalmology, Beijing Ophthalmology & Visual Sciences Key Laboratory, Capital Medical University, Beijing, 100730, China
| | - Yan Shi
- Beijing Tongren Eye Center Research Ward, Beijing Tongren Hospital, Beijing Institute of Ophthalmology, Beijing Ophthalmology & Visual Sciences Key Laboratory, Capital Medical University, Beijing, 100730, China.
| | - Zhigang Fan
- Beijing Tongren Eye Center Research Ward, Beijing Tongren Hospital, Beijing Institute of Ophthalmology, Beijing Ophthalmology & Visual Sciences Key Laboratory, Capital Medical University, Beijing, 100730, China.
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2
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Jackson D, Moosajee M. The Genetic Determinants of Axial Length: From Microphthalmia to High Myopia in Childhood. Annu Rev Genomics Hum Genet 2023; 24:177-202. [PMID: 37624667 DOI: 10.1146/annurev-genom-102722-090617] [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: 08/27/2023]
Abstract
The axial length of the eye is critical for normal visual function by enabling light to precisely focus on the retina. The mean axial length of the adult human eye is 23.5 mm, but the molecular mechanisms regulating ocular axial length remain poorly understood. Underdevelopment can lead to microphthalmia (defined as a small eye with an axial length of less than 19 mm at 1 year of age or less than 21 mm in adulthood) within the first trimester of pregnancy. However, continued overgrowth can lead to axial high myopia (an enlarged eye with an axial length of 26.5 mm or more) at any age. Both conditions show high genetic and phenotypic heterogeneity associated with significant visual morbidity worldwide. More than 90 genes can contribute to microphthalmia, and several hundred genes are associated with myopia, yet diagnostic yields are low. Crucially, the genetic pathways underpinning the specification of eye size are only now being discovered, with evidence suggesting that shared molecular pathways regulate under- or overgrowth of the eye. Improving our mechanistic understanding of axial length determination will help better inform us of genotype-phenotype correlations in both microphthalmia and myopia, dissect gene-environment interactions in myopia, and develop postnatal therapies that may influence overall eye growth.
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Affiliation(s)
- Daniel Jackson
- Institute of Ophthalmology, University College London, London, United Kingdom;
| | - Mariya Moosajee
- Institute of Ophthalmology, University College London, London, United Kingdom;
- The Francis Crick Institute, London, United Kingdom
- Moorfields Eye Hospital NHS Foundation Trust, London, United Kingdom
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3
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Hassall MM, Javadiyan S, Klebe S, Awadalla MS, Sharma S, Qassim A, White M, Thomas PQ, Craig JE, Siggs OM. Phenotypic consequences of a nanophthalmos-associated TMEM98 variant in human and mouse. Sci Rep 2023; 13:11017. [PMID: 37419942 PMCID: PMC10328987 DOI: 10.1038/s41598-023-37855-x] [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: 04/03/2023] [Accepted: 06/28/2023] [Indexed: 07/09/2023] Open
Abstract
Nanophthalmos is characterised by shorter posterior and anterior segments of the eye, with a predisposition towards high hyperopia and primary angle-closure glaucoma. Variants in TMEM98 have been associated with autosomal dominant nanophthalmos in multiple kindreds, but definitive evidence for causation has been limited. Here we used CRISPR/Cas9 mutagenesis to recreate the human nanophthalmos-associated TMEM98 p.(Ala193Pro) variant in mice. The p.(Ala193Pro) variant was associated with ocular phenotypes in both mice and humans, with dominant inheritance in humans and recessive inheritance in mice. Unlike their human counterparts, p.(Ala193Pro) homozygous mutant mice had normal axial length, normal intraocular pressure, and structurally normal scleral collagen. However, in both homozygous mice and heterozygous humans, the p.(Ala193Pro) variant was associated with discrete white spots throughout the retinal fundus, with corresponding retinal folds on histology. This direct comparison of a TMEM98 variant in mouse and human suggests that certain nanophthalmos-associated phenotypes are not only a consequence of a smaller eye, but that TMEM98 may itself play a primary role in retinal and scleral structure and integrity.
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Affiliation(s)
- Mark M Hassall
- Department of Ophthalmology, Flinders University, Bedford Park, SA, Australia.
| | - Shari Javadiyan
- Department of Ophthalmology, Flinders University, Bedford Park, SA, Australia
| | - Sonja Klebe
- Department of Anatomical Pathology, Flinders University, Bedford Park, SA, Australia
| | - Mona S Awadalla
- Department of Ophthalmology, Flinders University, Bedford Park, SA, Australia
| | - Shiwani Sharma
- Department of Ophthalmology, Flinders University, Bedford Park, SA, Australia
| | - Ayub Qassim
- Department of Ophthalmology, Flinders University, Bedford Park, SA, Australia
| | - Melissa White
- Department of Molecular and Cellular Biology and Robinson Research Institute, University of Adelaide, Adelaide, Australia
| | - Paul Q Thomas
- Department of Molecular and Cellular Biology and Robinson Research Institute, University of Adelaide, Adelaide, Australia
| | - Jamie E Craig
- Department of Ophthalmology, Flinders University, Bedford Park, SA, Australia
| | - Owen M Siggs
- Department of Ophthalmology, Flinders University, Bedford Park, SA, Australia.
- Garvan Institute of Medical Research, Darlinghurst, NSW, Australia.
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4
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Myelin regulatory factor deficiency is associated with the retinal photoreceptor defects in mice. Vis Neurosci 2021; 38:E005. [PMID: 33934732 DOI: 10.1017/s0952523821000043] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
Previously, we reported the myelin regulatory factor (MYRF) as a candidate gene for nanophthalmos. We have also produced Myrf knockdown (Myrf+/-) mouse strain to investigate the cellular and molecular phenotypes of reduced MYRF expression in the retina. Myrf+/- mouse strain was generated using the CRISPR/Cas9 system. Optomotor response system, electroretinogram (ERG), spectral-domain optical coherence tomography (SD-OCT), histology, and immunohistochemistry were performed to evaluate retinal spatial vision, electrophysiological function, retinal thickness, and pathological changes in cone or rod photoreceptors, respectively. RNA sequencing (RNA-seq) was performed to investigate the underlying molecular mechanism linking Myrf deficiency with photoreceptor defects. The genotype and phenotype of CRISPR/Cas9-induced Myrf+/- mice and their offspring were comprehensively investigated. Photoreceptor defects were detected in the retinas of Myrf+/- mice. Visual acuity and ERG responses were decreased in Myrf+/- mice compared with the control mice (Myrf+/+). The loss of cone and rod neurons was proportional to the decreased outer nuclear layer (ONL) thickness. Moreover, RNA-seq revealed that phototransduction and estrogen signaling pathways played important roles in the Kyoto Encyclopedia of Genes and Genomes (KEGG) analysis. Myrf+/- mouse strain provides a good model to investigate the function of the MYRF gene. Photoreceptor defects with impaired functions of spatial vision and retinal electrophysiology indicate an important role played by MYRF in retinal development. Alterations in phototransduction and estrogen signaling pathways play important roles in linking Myrf deficiency with retinal photoreceptor defects.
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5
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Huang H, Zhou F, Zhou S, Qiu M. MYRF: A Mysterious Membrane-Bound Transcription Factor Involved in Myelin Development and Human Diseases. Neurosci Bull 2021; 37:881-884. [PMID: 33864620 DOI: 10.1007/s12264-021-00678-9] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/27/2020] [Accepted: 12/18/2020] [Indexed: 11/24/2022] Open
Affiliation(s)
- Hao Huang
- Institute of Life Sciences, Zhejiang Key Laboratory of Organ Development and Regeneration, College of Life and Environmental Sciences, Hangzhou Normal University, Hangzhou, 311121, China
| | - Fang Zhou
- Institute of Life Sciences, Zhejiang Key Laboratory of Organ Development and Regeneration, College of Life and Environmental Sciences, Hangzhou Normal University, Hangzhou, 311121, China
| | - Shiyou Zhou
- The State Key Laboratory of Ophthalmology, Zhongshan Ophthalmic Center at Sun Yat-sen University, Guangzhou, 510060, China
| | - Mengsheng Qiu
- Institute of Life Sciences, Zhejiang Key Laboratory of Organ Development and Regeneration, College of Life and Environmental Sciences, Hangzhou Normal University, Hangzhou, 311121, China.
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Koli S, Labelle-Dumais C, Zhao Y, Paylakhi S, Nair KS. Identification of MFRP and the secreted serine proteases PRSS56 and ADAMTS19 as part of a molecular network involved in ocular growth regulation. PLoS Genet 2021; 17:e1009458. [PMID: 33755662 PMCID: PMC8018652 DOI: 10.1371/journal.pgen.1009458] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/20/2020] [Revised: 04/02/2021] [Accepted: 03/01/2021] [Indexed: 12/24/2022] Open
Abstract
Precise regulation of ocular size is a critical determinant of normal visual acuity. Although it is generally accepted that ocular growth relies on a cascade of signaling events transmitted from the retina to the sclera, the factors and mechanism(s) involved are poorly understood. Recent studies have highlighted the importance of the retinal secreted serine protease PRSS56 and transmembrane glycoprotein MFRP, a factor predominantly expressed in the retinal pigment epithelium (RPE), in ocular size determination. Mutations in PRSS56 and MFRP constitute a major cause of nanophthalmos, a condition characterized by severe reduction in ocular axial length/extreme hyperopia. Interestingly, common variants of these genes have been implicated in myopia, a condition associated with ocular elongation. Consistent with these findings, mice with loss of function mutation in PRSS56 or MFRP exhibit a reduction in ocular axial length. However, the molecular network and cellular processes involved in PRSS56- and MFRP-mediated ocular axial growth remain elusive. Here, we show that Adamts19 expression is significantly upregulated in the retina of mice lacking either Prss56 or Mfrp. Importantly, using genetic mouse models, we demonstrate that while ADAMTS19 is not required for ocular growth during normal development, its inactivation exacerbates ocular axial length reduction in Prss56 and Mfrp mutant mice. These results suggest that the upregulation of retinal Adamts19 is part of an adaptive molecular response to counteract impaired ocular growth. Using a complementary genetic approach, we show that loss of PRSS56 or MFRP function prevents excessive ocular axial growth in a mouse model of early-onset myopia caused by a null mutation in Irbp, thus, demonstrating that PRSS56 and MFRP are also required for pathological ocular elongation. Collectively, our findings provide new insights into the molecular network involved in ocular axial growth and support a role for molecular crosstalk between the retina and RPE involved in refractive development. During ocular refractive development, the eye’s growth is modulated, such that the ocular axial length matches the optical power enabling the eyes to achieve optimal focus. Alterations in ocular growth mainly contribute to refractive errors. Mutations in human PRSS56 and MFRP are responsible for nanophthalmos that exhibit a severe reduction in ocular axial length, and high hyperopia. Importantly, mutant mouse models lacking either Müller glia expressed PRSS56, or retinal pigment epithelium (RPE) localized MFRP exhibit ocular axial length reduction. Here, we have identified Adamts19 as a factor whose levels were significantly upregulated in the retina of mice lacking either Prss56 or Mfrp. Importantly, utilizing Adamts19 knockout mice we demonstrate that upregulation of retinal Adamts19 expression constitutes a compensatory mechanism that provides partial protection against ocular axial reduction due to mutation in Prss56 and Mfrp. Next, utilizing a mouse model of early-onset myopia, we demonstrate that the mutant Irbp induced ocular axial elongation is completely dependent on Prss56 as well as Mfrp, suggesting an interplay between Müller glia and RPE in the regulation of ocular axial growth. Collectively, these findings suggest that ocular refractive development relies on complex interactions occurring between genetic factors in the retina and RPE.
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Affiliation(s)
- Swanand Koli
- Department of Ophthalmology, University of California, San Francisco, California, United States of America
| | - Cassandre Labelle-Dumais
- Department of Ophthalmology, University of California, San Francisco, California, United States of America
| | - Yin Zhao
- Department of Ophthalmology, University of California, San Francisco, California, United States of America
| | - Seyyedhassan Paylakhi
- Department of Ophthalmology, University of California, San Francisco, California, United States of America
| | - K. Saidas Nair
- Department of Ophthalmology, University of California, San Francisco, California, United States of America
- Department of Anatomy, University of California, San Francisco, California, United States of America
- * E-mail:
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7
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Yu X, Sun N, Yang X, Zhao Z, Su X, Zhang J, He Y, Lin Y, Ge J, Fan Z. Nanophthalmos-Associated MYRF Gene Mutation Causes Ciliary Zonule Defects in Mice. Invest Ophthalmol Vis Sci 2021; 62:1. [PMID: 33646289 PMCID: PMC7937999 DOI: 10.1167/iovs.62.3.1] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
Abstract
Purpose Patients with nanophthalmos who undergo intraocular surgery often present with abnormal ciliary zonules. In a previous study, we reported mutation in MYRF that is implicated in the pathogenesis of nanophthalmos. The aim of this study was to model the mutation in mice to explore the role of MYRF on zonule structure and its major molecular composition, including FBN1 and FBN2. Methods Human MYRF nanophthalmos frameshift mutation was generated in mouse using the CRISPR-Cas9 system. PCR and Sanger sequencing were used for genotype analysis of the mice model. Anterior chamber depth (ACD) was measured using hematoxylin and eosin–stained histology samples. Morphologic analysis of ciliary zonules was carried out using silver staining and immunofluorescence. Transcript and protein expression levels of MYRF, FBN1, and FBN2 in ciliary bodies were quantified using quantitative real-time PCR (qRT-PCR) and Western blot. Results A nanophthalmos frameshift mutation (c.789delC, p.N264fs) of MYRF in mice showed ocular phenotypes similar to those reported in patients with nanophthalmos. ACD was reduced in MYRF mutant mice (MYRFmut/+) compared with that in littermate control mice (MYRF+/+). In addition, the morphology of ciliary zonules showed reduced zonular fiber density and detectable structural dehiscence of zonular fibers. Furthermore, qRT-PCR analysis and Western blot showed a significant decrease in mRNA expression levels of MYRF, FBN1, and FBN2 in MYRFmut/+ mice. Conclusions Changes in the structure and major molecular composition of ciliary zonules accompanied with shallowing anterior chamber were detected in MYRFmut/+ mice. Therefore, MYRF mutant mice strain is a useful model for exploring pathogenesis of zonulopathy, which is almost elusive for basic researches due to lack of appropriate animal models.
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Affiliation(s)
- Xiaowei Yu
- State Key Laboratory of Ophthalmology, Department of Glaucoma, Zhongshan Ophthalmic Center, Sun Yat-sen University, Guangzhou, Guangdong, China
| | - Nannan Sun
- State Key Laboratory of Ophthalmology, Department of Glaucoma, Zhongshan Ophthalmic Center, Sun Yat-sen University, Guangzhou, Guangdong, China
| | - Xue Yang
- State Key Laboratory of Ophthalmology, Department of Glaucoma, Zhongshan Ophthalmic Center, Sun Yat-sen University, Guangzhou, Guangdong, China
| | - Zhenni Zhao
- State Key Laboratory of Ophthalmology, Department of Glaucoma, Zhongshan Ophthalmic Center, Sun Yat-sen University, Guangzhou, Guangdong, China
| | - Xiaoqian Su
- State Key Laboratory of Ophthalmology, Department of Glaucoma, Zhongshan Ophthalmic Center, Sun Yat-sen University, Guangzhou, Guangdong, China
| | - Jiamin Zhang
- State Key Laboratory of Ophthalmology, Department of Glaucoma, Zhongshan Ophthalmic Center, Sun Yat-sen University, Guangzhou, Guangdong, China
| | - Yuqing He
- State Key Laboratory of Ophthalmology, Department of Glaucoma, Zhongshan Ophthalmic Center, Sun Yat-sen University, Guangzhou, Guangdong, China
| | - Yixiu Lin
- State Key Laboratory of Ophthalmology, Department of Glaucoma, Zhongshan Ophthalmic Center, Sun Yat-sen University, Guangzhou, Guangdong, China
| | - Jian Ge
- State Key Laboratory of Ophthalmology, Department of Glaucoma, Zhongshan Ophthalmic Center, Sun Yat-sen University, Guangzhou, Guangdong, China
| | - Zhigang Fan
- State Key Laboratory of Ophthalmology, Department of Glaucoma, Zhongshan Ophthalmic Center, Sun Yat-sen University, Guangzhou, Guangdong, China
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8
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A novel proline substitution (Arg201Pro) in alpha helix 8 of TMEM98 causes autosomal dominant nanophthalmos-4, closed angle glaucoma and attenuated visual acuity. Exp Eye Res 2021; 205:108497. [PMID: 33596443 DOI: 10.1016/j.exer.2021.108497] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/09/2020] [Revised: 02/04/2021] [Accepted: 02/09/2021] [Indexed: 11/24/2022]
Abstract
Nanophthalmos-4 is a rare autosomal dominant disorder caused by two known variations in TMEM98. An Austrian Caucasian pedigree was identified suffering from nanophthalmos and late onset angle-closure glaucoma and premature loss of visual acuity. Whole exome sequencing identified segregation of a c.602G > C transversion in TMEM98 (p.Arg201Pro) as potentially causative. A protein homology model generated showed a TMEM98 structure comprising α4, α5/6, α7 and α8 antiparallel helix bundles and two predicted transmembrane domains in α1 and α7 that have been confirmed in vitro. Both p.Arg201Pro and the two missense variations representing proline insertions identified previously to cause nanophthalmos-4 (p.Ala193Pro and p.His196Pro) are located in the charge polarized helix α8 (p.183-p210). Stability of the C-terminal alpha helical structure of TMEM98 is therefore essential to prevent the development of human nanophthalmos-4. Precise molecular diagnosis could lead to the development of tailored therapies for patients with orphan ocular disease.
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9
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Kuchtey RW. Not too long, not too short: Goldilocks principle of eye size. PLoS Genet 2020; 16:e1008914. [PMID: 32667907 PMCID: PMC7363070 DOI: 10.1371/journal.pgen.1008914] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022] Open
Affiliation(s)
- Rachel W. Kuchtey
- Department of Ophthalmology and Visual Sciences, Vanderbilt University Medical Center, Nashville, Tennessee, United States of America
- Department of Molecular Physiology and Biophysics, Vanderbilt University, Nashville, Tennessee, United States of America
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10
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Cross SH, Mckie L, Hurd TW, Riley S, Wills J, Barnard AR, Young F, MacLaren RE, Jackson IJ. The nanophthalmos protein TMEM98 inhibits MYRF self-cleavage and is required for eye size specification. PLoS Genet 2020; 16:e1008583. [PMID: 32236127 PMCID: PMC7153906 DOI: 10.1371/journal.pgen.1008583] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2019] [Revised: 04/13/2020] [Accepted: 03/06/2020] [Indexed: 12/31/2022] Open
Abstract
The precise control of eye size is essential for normal vision. TMEM98 is a highly conserved and widely expressed gene which appears to be involved in eye size regulation. Mutations in human TMEM98 are found in patients with nanophthalmos (very small eyes) and variants near the gene are associated in population studies with myopia and increased eye size. As complete loss of function mutations in mouse Tmem98 result in perinatal lethality, we produced mice deficient for Tmem98 in the retinal pigment epithelium (RPE), where Tmem98 is highly expressed. These mice have greatly enlarged eyes that are very fragile with very thin retinas, compressed choroid and thin sclera. To gain insight into the mechanism of action we used a proximity labelling approach to discover interacting proteins and identified MYRF as an interacting partner. Mutations of MYRF are also associated with nanophthalmos. The protein is an endoplasmic reticulum-tethered transcription factor which undergoes autoproteolytic cleavage to liberate the N-terminal part which then translocates to the nucleus where it acts as a transcription factor. We find that TMEM98 inhibits the self-cleavage of MYRF, in a novel regulatory mechanism. In RPE lacking TMEM98, MYRF is ectopically activated and abnormally localised to the nuclei. Our findings highlight the importance of the interplay between TMEM98 and MYRF in determining the size of the eye.
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Affiliation(s)
- Sally H. Cross
- MRC Human Genetics Unit, MRC Institute of Genetics and Molecular Medicine, University of Edinburgh, Edinburgh, United Kingdom
- * E-mail:
| | - Lisa Mckie
- MRC Human Genetics Unit, MRC Institute of Genetics and Molecular Medicine, University of Edinburgh, Edinburgh, United Kingdom
| | - Toby W. Hurd
- MRC Human Genetics Unit, MRC Institute of Genetics and Molecular Medicine, University of Edinburgh, Edinburgh, United Kingdom
| | - Sam Riley
- MRC Human Genetics Unit, MRC Institute of Genetics and Molecular Medicine, University of Edinburgh, Edinburgh, United Kingdom
| | - Jimi Wills
- MRC Human Genetics Unit, MRC Institute of Genetics and Molecular Medicine, University of Edinburgh, Edinburgh, United Kingdom
| | - Alun R. Barnard
- Nuffield Laboratory of Ophthalmology, Nuffield Department of Clinical Neurosciences, University of Oxford, The John Radcliffe Hospital, Oxford, United Kingdom
| | - Fiona Young
- Electron Microscopy, Pathology, Western General Hospital, Edinburgh, United Kingdom
| | - Robert E. MacLaren
- Nuffield Laboratory of Ophthalmology, Nuffield Department of Clinical Neurosciences, University of Oxford, The John Radcliffe Hospital, Oxford, United Kingdom
| | - Ian J. Jackson
- MRC Human Genetics Unit, MRC Institute of Genetics and Molecular Medicine, University of Edinburgh, Edinburgh, United Kingdom
- Roslin Institute, University of Edinburgh, Easter Bush, Midlothian, United Kingdom
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11
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van der Wal T, Lambooij JP, van Amerongen R. TMEM98 is a negative regulator of FRAT mediated Wnt/ß-catenin signalling. PLoS One 2020; 15:e0227435. [PMID: 31961879 PMCID: PMC6974163 DOI: 10.1371/journal.pone.0227435] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/02/2019] [Accepted: 12/18/2019] [Indexed: 12/19/2022] Open
Abstract
Wnt/ß-catenin signalling is crucial for maintaining the balance between cell proliferation and differentiation, both during tissue morphogenesis and in tissue maintenance throughout postnatal life. Whereas the signalling activities of the core Wnt/ß-catenin pathway components are understood in great detail, far less is known about the precise role and regulation of the many different modulators of Wnt/ß-catenin signalling that have been identified to date. Here we describe TMEM98, a putative transmembrane protein of unknown function, as an interaction partner and regulator of the GSK3-binding protein FRAT2. We show that TMEM98 reduces FRAT2 protein levels and, accordingly, inhibits the FRAT2-mediated induction of ß-catenin/TCF signalling. We also characterize the intracellular trafficking of TMEM98 in more detail and show that it is recycled between the plasma membrane and the Golgi. Together, our findings not only reveal a new layer of regulation for Wnt/ß-catenin signalling, but also a new biological activity for TMEM98.
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Affiliation(s)
- Tanne van der Wal
- Section of Molecular Cytology, Swammerdam Institute for Life Sciences, University of Amsterdam, Amsterdam, the Netherlands
- Van Leeuwenhoek Centre for Advanced Microscopy, University of Amsterdam, Amsterdam, the Netherlands
| | - Jan-Paul Lambooij
- Division of Molecular Genetics, Netherlands Cancer Institute, Amsterdam, the Netherlands
| | - Renée van Amerongen
- Section of Molecular Cytology, Swammerdam Institute for Life Sciences, University of Amsterdam, Amsterdam, the Netherlands
- Van Leeuwenhoek Centre for Advanced Microscopy, University of Amsterdam, Amsterdam, the Netherlands
- * E-mail:
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12
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Siggs OM, Souzeau E, Breen J, Qassim A, Zhou T, Dubowsky A, Ruddle JB, Craig JE. Autosomal dominant nanophthalmos and high hyperopia associated with a C-terminal frameshift variant in MYRF. Mol Vis 2019; 25:527-534. [PMID: 31700225 PMCID: PMC6817736] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/23/2019] [Accepted: 09/19/2019] [Indexed: 10/27/2022] Open
Abstract
Purpose Nanophthalmos is a rare subtype of microphthalmia associated with high hyperopia and an increased risk of angle-closure glaucoma. We investigated the genetic cause of nanophthalmos and high hyperopia in an autosomal dominant kindred. Methods A proband with short axial length, high hyperopia, and dextrocardia was subjected to exome sequencing. Human and rodent gene expression data sets were used to investigate the expression of relevant genes. Results We identified a segregating heterozygous frameshift variant at the 3' end of the penultimate exon of MYRF. Using Myc-MYRF chromatin immunoprecipitation data from rat oligodendrocytes, MYRF was found to bind immediately upstream of the transcriptional start site of Tmem98, a gene that itself has been implicated in autosomal dominant nanophthalmos. MYRF and TMEM98 were found to be expressed in the human retina, with a similar pattern of expression across several dissected human eye tissues. Conclusions C-terminal variants in MYRF, which are expected to escape nonsense-mediated decay, represent a rare cause of autosomal dominant nanophthalmos with or without dextrocardia or congenital diaphragmatic hernia.
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Affiliation(s)
- Owen M. Siggs
- Department of Ophthalmology, Flinders University, Bedford Park, South Australia, Australia
| | - Emmanuelle Souzeau
- Department of Ophthalmology, Flinders University, Bedford Park, South Australia, Australia
| | - James Breen
- South Australian Health and Medical Research Institute, Adelaide, South Australia, Australia
| | - Ayub Qassim
- Department of Ophthalmology, Flinders University, Bedford Park, South Australia, Australia
| | - Tiger Zhou
- Department of Ophthalmology, Flinders University, Bedford Park, South Australia, Australia
| | | | - Jonathan B. Ruddle
- Department of Ophthalmology, University of Melbourne, Melbourne, Victoria, Australia
| | - Jamie E. Craig
- Department of Ophthalmology, Flinders University, Bedford Park, South Australia, Australia
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