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Hizem S, Maamouri R, Zaouak A, Rejeb I, Karoui S, Sebai M, Jilani H, Elaribi Y, Fenniche S, Cheour M, Bilan F, Ben Jemaa L. Absent meibomian glands and cone dystrophy in ADULT syndrome: identification by whole exome sequencing of pathogenic variants in two causal genes TP63 and CNGB3. Ophthalmic Genet 2024; 45:84-94. [PMID: 37158316 DOI: 10.1080/13816810.2023.2206891] [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: 09/30/2022] [Accepted: 04/20/2023] [Indexed: 05/10/2023]
Abstract
BACKGROUND Ectrodactyly is a rare congenital limb malformation characterized by a deep median cleft of the hand and/or foot due to the absence of central rays. It could be isolated or depicts a part of diverse syndromic forms. Heterozygous pathogenic variants in the TP63 gene are responsible for at least four rare syndromic human disorders associated with ectrodactyly. Among them, ADULT (Acro-Dermato-Ungual-Lacrimal-Tooth) syndrome is characterized by ectodermal dysplasia, excessive freckling, nail dysplasia, and lacrimal duct obstruction, in addition to ectrodactyly and/or syndactyly. Ophthalmic findings are very common in TP63-related disorders, consisting mainly of lacrimal duct hypoplasia. Absent meibomian glands have also been well documented in EEC3 (Ectrodactyly Ectodermal dysplasia Cleft lip/palate) syndrome but not in ADULT syndrome. METHODS We report a case of syndromic ectrodactyly consistent with ADULT syndrome, with an additional ophthalmic manifestation of agenesis of meibomian glands. The proband, as well as her elder sister, presented with congenital cone dystrophy.The molecular investigation was performed in the proband using Whole Exome Sequencing. Family segregation of the identified variants was confirmed by Sanger sequencing. RESULTS Two clinically relevant variants were found in the proband: the novel de novo heterozygous missense c.931A > G (p.Ser311Gly) in the TP63 gene classified as pathogenic, and the homozygous nonsense pathogenic c.1810C > T (p.Arg604Ter) in the CNGB3 gene. The same homozygous CNGB3 variation was also found in the sister, explaining the cone dystrophy in both cases. CONCLUSIONS Whole Exome Sequencing allowed dual molecular diagnoses: de novo TP63-related syndromic ectrodactyly and familial CNGB3-related congenital cone dystrophy.
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Affiliation(s)
- Syrine Hizem
- Department of congenital and hereditary diseases, Mongi Slim hospital, La Marsa, Tunisia
- Human genetics laboratory, LR99ES10- Faculty of Medicine of Tunis, University of Tunis El Manar, Tunis, Tunisia
- Faculty of Medicine of Tunis, University of Tunis El Manar, Tunis, Tunisia
| | - Rym Maamouri
- Faculty of Medicine of Tunis, University of Tunis El Manar, Tunis, Tunisia
- Department of Ophthalmology, Habib Thameur hospital, Tunis, Tunisia
| | - Anissa Zaouak
- Faculty of Medicine of Tunis, University of Tunis El Manar, Tunis, Tunisia
- Department of Dermatology, Genodermatosis and Cancers Laboratory LR12SP03, Habib Thameur Hospital, Tunis, Tunisia
| | - Imen Rejeb
- Department of congenital and hereditary diseases, Mongi Slim hospital, La Marsa, Tunisia
- Maternal and Child health laboratory, LR22SP01- Mongi Slim Hospital, Tunis, Tunisia
| | - Sana Karoui
- Department of congenital and hereditary diseases, Mongi Slim hospital, La Marsa, Tunisia
- Faculty of Medicine of Tunis, University of Tunis El Manar, Tunis, Tunisia
- Maternal and Child health laboratory, LR22SP01- Mongi Slim Hospital, Tunis, Tunisia
| | - Molka Sebai
- Department of congenital and hereditary diseases, Mongi Slim hospital, La Marsa, Tunisia
- Human genetics laboratory, LR99ES10- Faculty of Medicine of Tunis, University of Tunis El Manar, Tunis, Tunisia
- Faculty of Medicine of Tunis, University of Tunis El Manar, Tunis, Tunisia
| | - Houweyda Jilani
- Department of congenital and hereditary diseases, Mongi Slim hospital, La Marsa, Tunisia
- Faculty of Medicine of Tunis, University of Tunis El Manar, Tunis, Tunisia
| | - Yasmina Elaribi
- Department of congenital and hereditary diseases, Mongi Slim hospital, La Marsa, Tunisia
- Faculty of Medicine of Tunis, University of Tunis El Manar, Tunis, Tunisia
| | - Sami Fenniche
- Faculty of Medicine of Tunis, University of Tunis El Manar, Tunis, Tunisia
- Department of Dermatology, Genodermatosis and Cancers Laboratory LR12SP03, Habib Thameur Hospital, Tunis, Tunisia
| | - Monia Cheour
- Faculty of Medicine of Tunis, University of Tunis El Manar, Tunis, Tunisia
- Department of Ophthalmology, Habib Thameur hospital, Tunis, Tunisia
| | - Frédéric Bilan
- Laboratoire de Génétique, Service de Génétique, CHU Poitiers, Poitiers, France
| | - Lamia Ben Jemaa
- Department of congenital and hereditary diseases, Mongi Slim hospital, La Marsa, Tunisia
- Faculty of Medicine of Tunis, University of Tunis El Manar, Tunis, Tunisia
- Maternal and Child health laboratory, LR22SP01- Mongi Slim Hospital, Tunis, Tunisia
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Biology, Pathobiology and Gene Therapy of CNG Channel-Related Retinopathies. Biomedicines 2023; 11:biomedicines11020269. [PMID: 36830806 PMCID: PMC9953513 DOI: 10.3390/biomedicines11020269] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/08/2023] [Revised: 01/16/2023] [Accepted: 01/17/2023] [Indexed: 01/21/2023] Open
Abstract
The visual process begins with the absorption of photons by photopigments of cone and rod photoreceptors in the retina. In this process, the signal is first amplified by a cyclic guanosine monophosphate (cGMP)-based signaling cascade and then converted into an electrical signal by cyclic nucleotide-gated (CNG) channels. CNG channels are purely ligand-gated channels whose activity can be controlled by cGMP, which induces a depolarizing Na+/Ca2+ current upon binding to the channel. Structurally, CNG channels belong to the superfamily of pore-loop cation channels and share structural similarities with hyperpolarization-activated cyclic nucleotide (HCN) and voltage-gated potassium (KCN) channels. Cone and rod photoreceptors express distinct CNG channels encoded by homologous genes. Mutations in the genes encoding the rod CNG channel (CNGA1 and CNGB1) result in retinitis-pigmentosa-type blindness. Mutations in the genes encoding the cone CNG channel (CNGA3 and CNGB3) lead to achromatopsia. Here, we review the molecular properties of CNG channels and describe their physiological and pathophysiological roles in the retina. Moreover, we summarize recent activities in the field of gene therapy aimed at developing the first gene therapies for CNG channelopathies.
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Naggert ASEN, Collin GB, Wang J, Krebs MP, Chang B. A mouse model of cone photoreceptor function loss (cpfl9) with degeneration due to a mutation in Gucy2e. Front Mol Neurosci 2023; 15:1080136. [PMID: 36698779 PMCID: PMC9868315 DOI: 10.3389/fnmol.2022.1080136] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/25/2022] [Accepted: 12/15/2022] [Indexed: 01/11/2023] Open
Abstract
During routine screening of mouse strains and stocks by the Eye Mutant Resource at The Jackson Laboratory for genetic mouse models of human ocular disorders, we identified cpfl9, a mouse model with cone photoreceptor function loss. The mice exhibited an early-onset phenotype that was easily recognized by the absence of a cone-mediated b-wave electroretinography response and by a reduction in rod-mediated photoresponses at four weeks of age. By genetic mapping and high-throughput sequencing of a whole exome capture library of cpfl9, a homozygous 25 bp deletion within exon 11 of the Gucy2e gene was identified, which is predicted to result in a frame shift leading to premature termination. The corresponding protein in human, retinal guanylate cyclase 1 (GUCY2D), plays an important role in rod and cone photoreceptor cell function. Loss-of-function mutations in human GUCY2D cause LCA1, one of the most common forms of Leber congenital amaurosis, which results in blindness at birth or in early childhood. The early loss of cone and reduced rod photoreceptor cell function in the cpfl9 mutant is accompanied by a later, progressive loss of cone and rod photoreceptor cells, which may be relevant to understanding disease pathology in a subset of LCA1 patients and in individuals with cone-rod dystrophy caused by recessive GUCY2D variants. cpfl9 mice will be useful for studying the role of Gucy2e in the retina.
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Dai X, Jin X, Ye Q, Huang H, Duo L, Lu C, Bao J, Chen H. Intraperitoneal chromophore injections delay early-onset and rapid retinal cone degeneration in a mouse model of Leber congenital amaurosis. Exp Eye Res 2021; 212:108776. [PMID: 34582935 DOI: 10.1016/j.exer.2021.108776] [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] [Received: 05/28/2021] [Revised: 09/04/2021] [Accepted: 09/23/2021] [Indexed: 10/20/2022]
Abstract
Highly expressed in the retinal pigment epithelium (RPE), the RPE-specific 65-kDa (RPE65) enzyme is indispensable to generate 11-cis-retinal (11cRAL), a chromophore for rhodopsin and cone photopigments. RPE65 deficiency can lead to Leber congenital amaurosis type 2 (LCA2), in which the isomerization of photobleached all-trans-retinal into photosensitive 11cRAL is blocked, ultimately causing severe retinal dysfunction and degeneration. The related mouse models, which are constructed through gene knockout or caused by spontaneous mutations, morphologically present with early-onset and rapid retinal cone cells degeneration, including loss of short-wavelength-sensitive cone opsins (S-opsins) and mislocalization of medium-wavelength-sensitive cone opsins (M-opsins). Studies have shown that routine Rpe65 gene replacement therapy, mediated by an adeno-associated virus (AAV) vector, can restore RPE65 protein. However, AAV transfection and Rpe65 transgene expression require at least one to two weeks, and the treatment cannot fully block the early-onset cone degeneration. To determine the feasibility of delaying cone degeneration before gene therapy, we investigated the impact of 11cRAL treatment in an early-age LCA2 retinal degeneration 12 (rd12) mouse model. Similar to human patients, the mouse model carries a spontaneous mutation in the Rpe65 gene, which results in disrupted endogenous 11cRAL regeneration. We found that RPE65 deficiency did not notably affect rodent retinal vessels. Under red light illumination, the rd12 mice were intraperitoneally injected with exogenous 11cRAL from postnatal day (P) 14 to P21. Three days after the last injection, a notable recovery of retinal function was observed using scotopic and photopic electroretinograms. Using optical coherence tomography and histological analyses of the deficient retinas, we found changes in the thickness of the photoreceptor outer segment (OS); this change could be rescued by early 11cRAL treatment. In addition, the treatment notably preserved M- and S-opsins, both of which maintained appropriate localization inside cone cells, as shown by the wild-type mice. In contrast, the age-matched untreated rd12 mice were characterized by retinal S-opsin loss and M-opsin mislocalization from the photoreceptor OS to the inner segment, outer nuclear layer, or outer plexiform layer. Notably, 11cRAL treatment could not maintain retinal function for a long time. Ten days after the last injection, the rod and M-cone electroretinograms significantly decreased, and S-cone responses almost extinguished. Our findings suggest that early 11cRAL treatment is useful for restoring retinal function and rescuing morphology in the rd12 mouse model, and the early-onset and rapid cone degeneration can be delayed before gene therapy.
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Affiliation(s)
- Xufeng Dai
- School of Ophthalmology and Optometry, The Eye Hospital, Wenzhou Medical University, Wenzhou, Zhejiang, 325027, China; State Key Laboratory of Ophthalmology, Optometry, and Visual Science, 270 Xueyuan Road, Wenzhou, Zhejiang, 325027, China
| | - Xumin Jin
- Laboratory Animal Centre, Wenzhou Medical University, Wenzhou, Zhejiang, 325035, China
| | - Qian Ye
- State Key Laboratory of Ophthalmology, Optometry, and Visual Science, 270 Xueyuan Road, Wenzhou, Zhejiang, 325027, China
| | - Haixiao Huang
- School of Ophthalmology and Optometry, The Eye Hospital, Wenzhou Medical University, Wenzhou, Zhejiang, 325027, China
| | - Lan Duo
- School of Ophthalmology and Optometry, The Eye Hospital, Wenzhou Medical University, Wenzhou, Zhejiang, 325027, China; State Key Laboratory of Ophthalmology, Optometry, and Visual Science, 270 Xueyuan Road, Wenzhou, Zhejiang, 325027, China
| | - Chunjie Lu
- School of Ophthalmology and Optometry, The Eye Hospital, Wenzhou Medical University, Wenzhou, Zhejiang, 325027, China
| | - Jinhua Bao
- School of Ophthalmology and Optometry, The Eye Hospital, Wenzhou Medical University, Wenzhou, Zhejiang, 325027, China; State Key Laboratory of Ophthalmology, Optometry, and Visual Science, 270 Xueyuan Road, Wenzhou, Zhejiang, 325027, China.
| | - Hao Chen
- School of Ophthalmology and Optometry, The Eye Hospital, Wenzhou Medical University, Wenzhou, Zhejiang, 325027, China; State Key Laboratory of Ophthalmology, Optometry, and Visual Science, 270 Xueyuan Road, Wenzhou, Zhejiang, 325027, China.
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Tekavčič Pompe M, Vrabič N, Volk M, Meglič A, Jarc-Vidmar M, Peterlin B, Hawlina M, Fakin A. Disease Progression in CNGA3 and CNGB3 Retinopathy; Characteristics of Slovenian Cohort and Proposed OCT Staging Based on Pooled Data from 126 Patients from 7 Studies. Curr Issues Mol Biol 2021; 43:941-957. [PMID: 34449556 PMCID: PMC8929018 DOI: 10.3390/cimb43020067] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/08/2021] [Revised: 08/02/2021] [Accepted: 08/05/2021] [Indexed: 11/20/2022] Open
Abstract
Achromatopsia has been proposed to be a morphologically predominately stable retinopathy with rare reports of progression of structural changes in the macula. A five-grade system of optical coherence tomography (OCT) features has been used for the classification of structural macular changes. However, their association with age remains questionable. We characterized the Slovenian cohort of 12 patients with pathogenic variants in CNGA3 or CNGB3 who had been followed up with OCT for up to 9 years. Based on observed structural changes in association with age, the following four-stage classification of retinal morphological changes was proposed: (I) preserved inner segment ellipsoid band (Ise), (II) disrupted ISe, (III) ISe loss and (IV) ISe and RPE loss. Data from six previously published studies reporting OCT morphology in CNGA3 and CNGB3 patients were additionally collected, forming the largest CNGA3/CNGB3 cohort to date, comprising 126 patients aged 1–71 years. Multiple regression analysis showed a significant correlation of OCT stage with age (p < 0.001) and no correlation with gene (p > 0.05). The median ages of patients with stages I–IV were 12 years, 23 years, 27 years and 48 years, respectively, and no patient older than 50 years had continuous ISe. Our findings suggest that achromatopsia presents with slowly but steadily progressive structural changes of the macular outer retinal layers. However, whether morphological changes in time follow the proposed four-stage linear pattern needs to be confirmed in a long-term study.
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Affiliation(s)
- Manca Tekavčič Pompe
- Eye Hospital, University Medical Centre Ljubljana, 1000 Ljubljana, Slovenia; (M.T.P.); (N.V.); (A.M.); (M.J.-V.); (M.H.)
| | - Nika Vrabič
- Eye Hospital, University Medical Centre Ljubljana, 1000 Ljubljana, Slovenia; (M.T.P.); (N.V.); (A.M.); (M.J.-V.); (M.H.)
| | - Marija Volk
- Clinical Institute of Genomic Medicine, University Medical Centre Ljubljana, 1000 Ljubljana, Slovenia; (M.V.); (B.P.)
| | - Andrej Meglič
- Eye Hospital, University Medical Centre Ljubljana, 1000 Ljubljana, Slovenia; (M.T.P.); (N.V.); (A.M.); (M.J.-V.); (M.H.)
| | - Martina Jarc-Vidmar
- Eye Hospital, University Medical Centre Ljubljana, 1000 Ljubljana, Slovenia; (M.T.P.); (N.V.); (A.M.); (M.J.-V.); (M.H.)
| | - Borut Peterlin
- Clinical Institute of Genomic Medicine, University Medical Centre Ljubljana, 1000 Ljubljana, Slovenia; (M.V.); (B.P.)
| | - Marko Hawlina
- Eye Hospital, University Medical Centre Ljubljana, 1000 Ljubljana, Slovenia; (M.T.P.); (N.V.); (A.M.); (M.J.-V.); (M.H.)
| | - Ana Fakin
- Eye Hospital, University Medical Centre Ljubljana, 1000 Ljubljana, Slovenia; (M.T.P.); (N.V.); (A.M.); (M.J.-V.); (M.H.)
- Correspondence:
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Wang NK, Liu PK, Kong Y, Levi SR, Huang WC, Hsu CW, Wang HH, Chen N, Tseng YJ, Quinn PMJ, Tai MH, Lin CS, Tsang SH. Mouse Models of Achromatopsia in Addressing Temporal "Point of No Return" in Gene-Therapy. Int J Mol Sci 2021; 22:8069. [PMID: 34360834 PMCID: PMC8347118 DOI: 10.3390/ijms22158069] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/29/2021] [Revised: 07/22/2021] [Accepted: 07/25/2021] [Indexed: 12/03/2022] Open
Abstract
Achromatopsia is characterized by amblyopia, photophobia, nystagmus, and color blindness. Previous animal models of achromatopsia have shown promising results using gene augmentation to restore cone function. However, the optimal therapeutic window to elicit recovery remains unknown. Here, we attempted two rounds of gene augmentation to generate recoverable mouse models of achromatopsia including a Cnga3 model with a knock-in stop cassette in intron 5 using Easi-CRISPR (Efficient additions with ssDNA inserts-CRISPR) and targeted embryonic stem (ES) cells. This model demonstrated that only 20% of CNGA3 levels in homozygotes derived from target ES cells remained, as compared to normal CNGA3 levels. Despite the low percentage of remaining protein, the knock-in mouse model continued to generate normal cone phototransduction. Our results showed that a small amount of normal CNGA3 protein is sufficient to form "functional" CNG channels and achieve physiological demand for proper cone phototransduction. Thus, it can be concluded that mutating the Cnga3 locus to disrupt the functional tetrameric CNG channels may ultimately require more potent STOP cassettes to generate a reversible achromatopsia mouse model. Our data also possess implications for future CNGA3-associated achromatopsia clinical trials, whereby restoration of only 20% functional CNGA3 protein may be sufficient to form functional CNG channels and thus rescue cone response.
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Affiliation(s)
- Nan-Kai Wang
- Department of Ophthalmology, Edward S. Harkness Eye Institute, Columbia University Irving Medical Center, New York, NY 10032, USA; (N.-K.W.); (P.-K.L.); (Y.K.); (S.R.L.); (W.-C.H.); (C.-W.H.); (H.-H.W.); (N.C.); (P.M.J.Q.)
| | - Pei-Kang Liu
- Department of Ophthalmology, Edward S. Harkness Eye Institute, Columbia University Irving Medical Center, New York, NY 10032, USA; (N.-K.W.); (P.-K.L.); (Y.K.); (S.R.L.); (W.-C.H.); (C.-W.H.); (H.-H.W.); (N.C.); (P.M.J.Q.)
- Department of Ophthalmology, Kaohsiung Medical University Hospital, Kaohsiung Medical University, Kaohsiung 80756, Taiwan
- School of Medicine, College of Medicine, Kaohsiung Medical University, Kaohsiung 80708, Taiwan
- Institute of Biomedical Sciences, National Sun Yat-sen University, Kaohsiung 80424, Taiwan
| | - Yang Kong
- Department of Ophthalmology, Edward S. Harkness Eye Institute, Columbia University Irving Medical Center, New York, NY 10032, USA; (N.-K.W.); (P.-K.L.); (Y.K.); (S.R.L.); (W.-C.H.); (C.-W.H.); (H.-H.W.); (N.C.); (P.M.J.Q.)
| | - Sarah R. Levi
- Department of Ophthalmology, Edward S. Harkness Eye Institute, Columbia University Irving Medical Center, New York, NY 10032, USA; (N.-K.W.); (P.-K.L.); (Y.K.); (S.R.L.); (W.-C.H.); (C.-W.H.); (H.-H.W.); (N.C.); (P.M.J.Q.)
| | - Wan-Chun Huang
- Department of Ophthalmology, Edward S. Harkness Eye Institute, Columbia University Irving Medical Center, New York, NY 10032, USA; (N.-K.W.); (P.-K.L.); (Y.K.); (S.R.L.); (W.-C.H.); (C.-W.H.); (H.-H.W.); (N.C.); (P.M.J.Q.)
| | - Chun-Wei Hsu
- Department of Ophthalmology, Edward S. Harkness Eye Institute, Columbia University Irving Medical Center, New York, NY 10032, USA; (N.-K.W.); (P.-K.L.); (Y.K.); (S.R.L.); (W.-C.H.); (C.-W.H.); (H.-H.W.); (N.C.); (P.M.J.Q.)
| | - Hung-Hsi Wang
- Department of Ophthalmology, Edward S. Harkness Eye Institute, Columbia University Irving Medical Center, New York, NY 10032, USA; (N.-K.W.); (P.-K.L.); (Y.K.); (S.R.L.); (W.-C.H.); (C.-W.H.); (H.-H.W.); (N.C.); (P.M.J.Q.)
| | - Nelson Chen
- Department of Ophthalmology, Edward S. Harkness Eye Institute, Columbia University Irving Medical Center, New York, NY 10032, USA; (N.-K.W.); (P.-K.L.); (Y.K.); (S.R.L.); (W.-C.H.); (C.-W.H.); (H.-H.W.); (N.C.); (P.M.J.Q.)
| | - Yun-Ju Tseng
- Department of Pathology & Cell Biology, Columbia University Irving Medical Center, New York, NY 10032, USA; (Y.-J.T.); (C.-S.L.)
- Herbert Irving Comprehensive Cancer Center, Columbia University Irving Medical Center, New York, NY 10032, USA
| | - Peter M. J. Quinn
- Department of Ophthalmology, Edward S. Harkness Eye Institute, Columbia University Irving Medical Center, New York, NY 10032, USA; (N.-K.W.); (P.-K.L.); (Y.K.); (S.R.L.); (W.-C.H.); (C.-W.H.); (H.-H.W.); (N.C.); (P.M.J.Q.)
| | - Ming-Hong Tai
- Institute of Biomedical Sciences, National Sun Yat-sen University, Kaohsiung 80424, Taiwan
- Center for Neuroscience, National Sun Yat-sen University, Kaohsiung 80424, Taiwan
- Graduate Program in Marine Biotechnology, National Sun Yat-sen University, Kaohsiung 80424, Taiwan
| | - Chyuan-Sheng Lin
- Department of Pathology & Cell Biology, Columbia University Irving Medical Center, New York, NY 10032, USA; (Y.-J.T.); (C.-S.L.)
- Herbert Irving Comprehensive Cancer Center, Columbia University Irving Medical Center, New York, NY 10032, USA
| | - Stephen H. Tsang
- Department of Ophthalmology, Edward S. Harkness Eye Institute, Columbia University Irving Medical Center, New York, NY 10032, USA; (N.-K.W.); (P.-K.L.); (Y.K.); (S.R.L.); (W.-C.H.); (C.-W.H.); (H.-H.W.); (N.C.); (P.M.J.Q.)
- Jonas Children’s Vision Care, and Bernard and Shirlee Brown Glaucoma Laboratory, Columbia Stem Cell Initiative, Departments of Ophthalmology, Pathology and Cell Biology, Institute of Human Nutrition, Vagelos College of Physicians and Surgeons, Columbia University, New York, NY 10032, USA
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Yang F, Ma H, Butler MR, Ding XQ. Preservation of endoplasmic reticulum (ER) Ca 2+ stores by deletion of inositol-1,4,5-trisphosphate receptor type 1 promotes ER retrotranslocation, proteostasis, and protein outer segment localization in cyclic nucleotide-gated channel-deficient cone photoreceptors. FASEB J 2021; 35:e21579. [PMID: 33960001 DOI: 10.1096/fj.202002711r] [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] [Received: 12/11/2020] [Revised: 03/03/2021] [Accepted: 03/25/2021] [Indexed: 11/11/2022]
Abstract
Endoplasmic reticulum (ER) Ca2+ homeostasis relies on an appropriate balance between efflux- and influx-channel activity responding to dynamic changes of intracellular Ca2+ levels. Dysregulation of this complex signaling network has been shown to contribute to neuronal and photoreceptor death in neuro- and retinal degenerative diseases, respectively. In mice with cone cyclic nucleotide-gated (CNG) channel deficiency, a model of achromatopsia/cone dystrophy, cones display early-onset ER stress-associated apoptosis and protein mislocalization. Cones in these mice also show reduced cytosolic Ca2+ level and subsequent elevation in the ER Ca2+ -efflux-channel activity, specifically the inositol-1,4,5-trisphosphate receptor type 1 (IP3 R1), and deletion of IP3 R1 results in preservation of cones. This work investigated how preservation of ER Ca2+ stores leads to cone protection. We examined the effects of cone specific deletion of IP3 R1 on ER stress responses/cone death, protein localization, and ER proteostasis/ER-associated degradation. We demonstrated that deletion of IP3 R1 improves trafficking of cone-specific proteins M-/S-opsin and phosphodiesterase 6C to cone outer segments and reduces localization to cone inner segments. Consistent with the improved protein localization, deletion of IP3 R1 results in increased ER retrotranslocation protein expression, reduced proteasome subunit expression, reduced ER stress/cone death, and reduced retinal remodeling. We also observed the enhanced ER retrotranslocation in mice that have been treated with a chemical chaperone, supporting the connection between improved ER retrotranslocation/proteostasis and alleviation of ER stress. Findings from this work demonstrate the importance of ER Ca2+ stores in ER proteostasis and protein trafficking/localization in photoreceptors, strengthen the link between dysregulation of ER Ca2+ homeostasis and ER stress/cone degeneration, and support an involvement of improved ER proteostasis in ER Ca2+ preservation-induced cone protection; thereby identifying IP3 R1 as a critical mediator of ER stress and protein mislocalization and as a potential target to preserve cones in CNG channel deficiency.
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Affiliation(s)
- Fan Yang
- Department of Cell Biology, University of Oklahoma Health Sciences Center, Oklahoma City, OK, USA
| | - Hongwei Ma
- Department of Cell Biology, University of Oklahoma Health Sciences Center, Oklahoma City, OK, USA
| | - Michael R Butler
- Department of Cell Biology, University of Oklahoma Health Sciences Center, Oklahoma City, OK, USA
| | - Xi-Qin Ding
- Department of Cell Biology, University of Oklahoma Health Sciences Center, Oklahoma City, OK, USA
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Bales KL, Bentley MR, Croyle MJ, Kesterson RA, Yoder BK, Gross AK. BBSome Component BBS5 Is Required for Cone Photoreceptor Protein Trafficking and Outer Segment Maintenance. Invest Ophthalmol Vis Sci 2020; 61:17. [PMID: 32776140 PMCID: PMC7441369 DOI: 10.1167/iovs.61.10.17] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/20/2020] [Accepted: 07/15/2020] [Indexed: 01/07/2023] Open
Abstract
Purpose To identify the role of the BBSome protein Bardet-Biedl syndrome 5 (BBS5) in photoreceptor function, protein trafficking, and structure using a congenital mutant mouse model. Methods Bbs5-/- mice (2 and 9 months old) were used to assess retinal function and morphology. Hematoxylin and eosin staining of retinal sections was performed to visualize histology. Electroretinography was used to analyze rod and cone photoreceptor function. Retinal protein localization was visualized using immunofluorescence (IF) within retinal cryosections. TUNEL staining was used to quantify cell death. Transmission electron microscopy (TEM) was used to examine retinal ultrastructure. Results In the Bbs5-/- retina, there was a significant loss of nuclei in the outer nuclear layer accompanied by an increase in cell death. Through electroretinography, Bbs5-/- mice showed complete loss of cone photoreceptor function. IF revealed mislocalization of the cone-specific proteins M- and S-opsins, arrestin-4, CNGA3, and GNAT2, as well as a light-dependent arrestin-1 mislocalization, although perpherin-2 was properly localized. TEM revealed abnormal outer segment disk orientation in Bbs5-/-. Conclusions Collectively, these data suggest that, although BBS5 is a core BBSome component expressed in all ciliated cells, its role within the retina mediates specific photoreceptor protein cargo transport. In the absence of BBS5, cone-specific protein mislocalization and a loss of cone photoreceptor function occur.
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Affiliation(s)
- Katie L. Bales
- Department of Optometry and Vision Sciences, University of Alabama at Birmingham, Birmingham, Alabama, United States
| | - Melissa R. Bentley
- Department of Cell, Developmental, and Integrative Biology, University of Alabama at Birmingham, Birmingham, Alabama, United States
| | - Mandy J. Croyle
- Department of Cell, Developmental, and Integrative Biology, University of Alabama at Birmingham, Birmingham, Alabama, United States
| | - Robert A. Kesterson
- Department of Genetics, University of Alabama at Birmingham, Birmingham, Alabama, United States
| | - Bradley K. Yoder
- Department of Cell, Developmental, and Integrative Biology, University of Alabama at Birmingham, Birmingham, Alabama, United States
| | - Alecia K. Gross
- Department of Optometry and Vision Sciences, University of Alabama at Birmingham, Birmingham, Alabama, United States
- Department of Cell, Developmental, and Integrative Biology, University of Alabama at Birmingham, Birmingham, Alabama, United States
- Department of Neurobiology, University of Alabama at Birmingham, Birmingham, Alabama, United States
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9
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Yang F, Ma H, Butler MR, Ding XQ. Potential contribution of ryanodine receptor 2 upregulation to cGMP/PKG signaling-induced cone degeneration in cyclic nucleotide-gated channel deficiency. FASEB J 2020; 34:6335-6350. [PMID: 32173907 PMCID: PMC7299158 DOI: 10.1096/fj.201901951rr] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/01/2019] [Revised: 02/01/2020] [Accepted: 03/01/2020] [Indexed: 12/28/2022]
Abstract
Photoreceptor cyclic nucleotide-gated (CNG) channels regulate Ca2+ influx in rod and cone photoreceptors. Mutations in cone CNG channel subunits CNGA3 and CNGB3 are associated with achromatopsia and cone dystrophies. Mice lacking functional cone CNG channel show endoplasmic reticulum (ER) stress-associated cone degeneration. The elevated cyclic guanosine monophosphate (cGMP)/cGMP-dependent protein kinase (PKG) signaling and upregulation of the ER Ca2+ channel ryanodine receptor 2 (RyR2) have been implicated in cone degeneration. This work investigates the potential contribution of RyR2 to cGMP/PKG signaling-induced ER stress and cone degeneration. We demonstrated that the expression and activity of RyR2 were highly regulated by cGMP/PKG signaling. Depletion of cGMP by deleting retinal guanylate cyclase 1 or inhibition of PKG using chemical inhibitors suppressed the upregulation of RyR2 in CNG channel deficiency. Depletion of cGMP or deletion of Ryr2 equivalently inhibited unfolded protein response/ER stress, activation of the CCAAT-enhancer-binding protein homologous protein, and activation of the cyclic adenosine monophosphate response element-binding protein, leading to early-onset cone protection. In addition, treatment with cGMP significantly enhanced Ryr2 expression in cultured photoreceptor-derived Weri-Rb1 cells. Findings from this work demonstrate the regulation of cGMP/PKG signaling on RyR2 in the retina and support the role of RyR2 upregulation in cGMP/PKG signaling-induced ER stress and photoreceptor degeneration.
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Affiliation(s)
- Fan Yang
- Department of Cell Biology, University of Oklahoma Health Sciences Center, Oklahoma City, Oklahoma
| | - Hongwei Ma
- Department of Cell Biology, University of Oklahoma Health Sciences Center, Oklahoma City, Oklahoma
| | - Michael R. Butler
- Department of Cell Biology, University of Oklahoma Health Sciences Center, Oklahoma City, Oklahoma
| | - Xi-Qin Ding
- Department of Cell Biology, University of Oklahoma Health Sciences Center, Oklahoma City, Oklahoma
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10
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Ma H, Yang F, Ding XQ. Inhibition of thyroid hormone signaling protects retinal pigment epithelium and photoreceptors from cell death in a mouse model of age-related macular degeneration. Cell Death Dis 2020; 11:24. [PMID: 31932580 PMCID: PMC6957507 DOI: 10.1038/s41419-019-2216-7] [Citation(s) in RCA: 32] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/19/2019] [Revised: 12/11/2019] [Accepted: 12/12/2019] [Indexed: 02/01/2023]
Abstract
Age-related macular degeneration (AMD) is the leading cause of blindness in the elderly. Dry AMD is characterized by a progressive macular degeneration of the retinal pigment epithelium (RPE) and photoreceptors, and the RPE oxidative damage/dystrophy is at the core of the disease. Recent population/patients-based studies have shown an association of high free serum thyroid hormone (TH) levels with increased risk of AMD. This work investigated the effects of TH signaling inhibition on RPE and photoreceptor damage/cell death in an oxidative stress-induced mouse model of AMD. TH signaling inhibition was achieved by anti-thyroid drug treatment and oxidative stress was induced by sodium iodate (NaIO3) administration. Mice treated with NaIO3 showed severe RPE and photoreceptor cell death/necroptosis, destruction, oxidative damage, retinal stress, and reduced retinal function. Treatment with anti-thyroid drug protected RPE and photoreceptors from damage/cell death induced by NaIO3, reduced oxidative damage of RPE and photoreceptors, and preserved retinal function. Gene expression analysis showed that the NaIO3-induced RPE/photoreceptor damage/cell death involves multiple mechanisms, including cellular oxidative stress responses, activation of necroptosis/apoptosis signaling, and inflammatory responses. Treatment with anti-thyroid drug abolished these cellular stress/death responses. The findings of this study demonstrate a role of TH signaling in RPE and photoreceptor cell death after oxidative stress challenge, and support a role of TH signaling in the pathogenesis of AMD.
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Affiliation(s)
- Hongwei Ma
- Department of Cell Biology, University of Oklahoma Health Sciences Center, Oklahoma City, OK, USA
| | - Fan Yang
- Department of Cell Biology, University of Oklahoma Health Sciences Center, Oklahoma City, OK, USA
| | - Xi-Qin Ding
- Department of Cell Biology, University of Oklahoma Health Sciences Center, Oklahoma City, OK, USA.
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11
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Ma H, Yang F, Butler MR, Rapp J, Le YZ, Ding XQ. Ryanodine Receptor 2 Contributes to Impaired Protein Localization in Cyclic Nucleotide-Gated Channel Deficiency. eNeuro 2019; 6:ENEURO.0119-19.2019. [PMID: 31182474 PMCID: PMC6597858 DOI: 10.1523/eneuro.0119-19.2019] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/27/2019] [Revised: 05/20/2019] [Accepted: 05/21/2019] [Indexed: 01/28/2023] Open
Abstract
The photoreceptor cyclic nucleotide-gated (CNG) channel plays a pivotal role in phototransduction and cellular calcium homeostasis. Mutations in the cone photoreceptor CNG channel subunits CNGA3 and CNGB3 are associated with achromatopsia and cone dystrophies. CNG channel deficiency leads to endoplasmic reticulum (ER) stress-associated cone apoptosis, protein mislocalization, and ER calcium dysregulation. This work investigated the potential mechanisms of protein mislocalization associated with ER calcium dysregulation using Cnga3-/- mice lacking ER Ca2+ channel ryanodine receptor 2 (RyR2) specifically in cones. Deletion of Ryr2 improved outer segment (OS) localization of the cone proteins M-opsin, S-opsin, and cone phosphodiesterase subunit α' (PDE6C) and decreased inner segment localization. One-month-old Cnga3-/- mice showed ∼30% of M-opsin, 55% of S-opsin, and 50% of PDE6C localized to the OS. Cnga3-/- mice with Ryr2 deletion at the same age showed almost 60% of M-opsin, 70% of S-opsin, and 70% of PDE6C localized to the OS. Deletion of Ryr2 nearly completely reversed elevations of the ER stress markers phospho-IRE1α and phospho-eIF2α and suppressed cone apoptosis. Consistent with the improved cone protein localization and reduced ER stress/cone apoptosis, cone survival was improved by deletion of Ryr2 The number of cones was increased by ∼28% in 2- to 4-month-old Cnga3-/- mice with Ryr2 deletion compared with age-matched Cnga3-/- mice. This work demonstrates a role of RyR2/ER calcium dysregulation in protein mislocalization, ER stress, and cone death. The findings provide novel insights into the mechanisms of photoreceptor degeneration and support strategies targeting ER calcium regulation to manage retinal degeneration.
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Affiliation(s)
- Hongwei Ma
- Department of Cell Biology, University of Oklahoma Health Sciences Center (OUHSC), Oklahoma City, Oklahoma 73104
| | - Fan Yang
- Department of Cell Biology, University of Oklahoma Health Sciences Center (OUHSC), Oklahoma City, Oklahoma 73104
| | - Michael R Butler
- Department of Cell Biology, University of Oklahoma Health Sciences Center (OUHSC), Oklahoma City, Oklahoma 73104
| | - Jacob Rapp
- Department of Cell Biology, University of Oklahoma Health Sciences Center (OUHSC), Oklahoma City, Oklahoma 73104
| | - Yun-Zheng Le
- Department of Cell Biology, University of Oklahoma Health Sciences Center (OUHSC), Oklahoma City, Oklahoma 73104
- Department of Medicine, University of Oklahoma Health Sciences Center (OUHSC), Oklahoma City, Oklahoma 73104
- Department of Ophthalmology, University of Oklahoma Health Sciences Center (OUHSC), Oklahoma City, Oklahoma 73104
- Harold Hamm Diabetes Center, University of Oklahoma Health Sciences Center (OUHSC), Oklahoma City, Oklahoma 73104
| | - Xi-Qin Ding
- Department of Cell Biology, University of Oklahoma Health Sciences Center (OUHSC), Oklahoma City, Oklahoma 73104
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12
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Burkard M, Kohl S, Krätzig T, Tanimoto N, Brennenstuhl C, Bausch AE, Junger K, Reuter P, Sothilingam V, Beck SC, Huber G, Ding XQ, Mayer AK, Baumann B, Weisschuh N, Zobor D, Hahn GA, Kellner U, Venturelli S, Becirovic E, Charbel Issa P, Koenekoop RK, Rudolph G, Heckenlively J, Sieving P, Weleber RG, Hamel C, Zong X, Biel M, Lukowski R, Seeliger MW, Michalakis S, Wissinger B, Ruth P. Accessory heterozygous mutations in cone photoreceptor CNGA3 exacerbate CNG channel-associated retinopathy. J Clin Invest 2018; 128:5663-5675. [PMID: 30418171 PMCID: PMC6264655 DOI: 10.1172/jci96098] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/10/2017] [Accepted: 10/02/2018] [Indexed: 01/01/2023] Open
Abstract
Mutations in CNGA3 and CNGB3, the genes encoding the subunits of the tetrameric cone photoreceptor cyclic nucleotide-gated ion channel, cause achromatopsia, a congenital retinal disorder characterized by loss of cone function. However, a small number of patients carrying the CNGB3/c.1208G>A;p.R403Q mutation present with a variable retinal phenotype ranging from complete and incomplete achromatopsia to moderate cone dysfunction or progressive cone dystrophy. By exploring a large patient cohort and published cases, we identified 16 unrelated individuals who were homozygous or (compound-)heterozygous for the CNGB3/c.1208G>A;p.R403Q mutation. In-depth genetic and clinical analysis revealed a co-occurrence of a mutant CNGA3 allele in a high proportion of these patients (10 of 16), likely contributing to the disease phenotype. To verify these findings, we generated a Cngb3R403Q/R403Q mouse model, which was crossbred with Cnga3-deficient (Cnga3-/-) mice to obtain triallelic Cnga3+/- Cngb3R403Q/R403Q mutants. As in human subjects, there was a striking genotype-phenotype correlation, since the presence of 1 Cnga3-null allele exacerbated the cone dystrophy phenotype in Cngb3R403Q/R403Q mice. These findings strongly suggest a digenic and triallelic inheritance pattern in a subset of patients with achromatopsia/severe cone dystrophy linked to the CNGB3/p.R403Q mutation, with important implications for diagnosis, prognosis, and genetic counseling.
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Affiliation(s)
- Markus Burkard
- Department of Pharmacology, Toxicology and Clinical Pharmacy, Institute of Pharmacy
- Department of Vegetative and Clinical Physiology
| | - Susanne Kohl
- Molecular Genetics Laboratory, Institute for Ophthalmic Research, and
| | - Timm Krätzig
- Department of Pharmacology, Toxicology and Clinical Pharmacy, Institute of Pharmacy
| | - Naoyuki Tanimoto
- Division of Ocular Neurodegeneration, Institute for Ophthalmic Research, Centre for Ophthalmology, University of Tübingen, Tübingen, Germany
| | | | - Anne E. Bausch
- Department of Pharmacology, Toxicology and Clinical Pharmacy, Institute of Pharmacy
| | - Katrin Junger
- Department of Pharmacology, Toxicology and Clinical Pharmacy, Institute of Pharmacy
| | - Peggy Reuter
- Molecular Genetics Laboratory, Institute for Ophthalmic Research, and
| | - Vithiyanjali Sothilingam
- Division of Ocular Neurodegeneration, Institute for Ophthalmic Research, Centre for Ophthalmology, University of Tübingen, Tübingen, Germany
| | - Susanne C. Beck
- Division of Ocular Neurodegeneration, Institute for Ophthalmic Research, Centre for Ophthalmology, University of Tübingen, Tübingen, Germany
| | - Gesine Huber
- Division of Ocular Neurodegeneration, Institute for Ophthalmic Research, Centre for Ophthalmology, University of Tübingen, Tübingen, Germany
| | - Xi-Qin Ding
- Department of Cell Biology, University of Oklahoma Health Sciences Center, Oklahoma City, Oklahoma, USA
| | - Anja K. Mayer
- Molecular Genetics Laboratory, Institute for Ophthalmic Research, and
| | - Britta Baumann
- Molecular Genetics Laboratory, Institute for Ophthalmic Research, and
| | - Nicole Weisschuh
- Molecular Genetics Laboratory, Institute for Ophthalmic Research, and
| | - Ditta Zobor
- Institute of Ophthalmic Research, Centre for Ophthalmology, University of Tübingen, Tübingen, Germany
| | - Gesa-Astrid Hahn
- Molecular Genetics Laboratory, Institute for Ophthalmic Research, and
| | - Ulrich Kellner
- Rare Retinal Disease Center, Augenzentrum Siegburg, MVZ ADTC Siegburg GmbH, Siegburg, Germany
| | | | - Elvir Becirovic
- Center for Integrated Protein Science Munich CiPSM and Department of Pharmacy–Center for Drug Research, Ludwig-Maximilians-Universität München, Munich, Germany
| | - Peter Charbel Issa
- Oxford Eye Hospital, OUH NHS Foundation Trust and the Nuffield Laboratory of Ophthalmology, Department of Clinical Neurosciences, University of Oxford, Oxford, United Kingdom
| | - Robert K. Koenekoop
- McGill Ocular Genetics Centre, McGill University Health Centre, Montreal, Quebec, Canada
| | | | | | - Paul Sieving
- The National Eye Institute, Bethesda, Maryland, USA
| | - Richard G. Weleber
- Casey Eye Institute, Department of Ophthalmogenetics, Portland, Oregon, USA
| | - Christian Hamel
- INSERM U583, Institut des Neurosciences, Montpellier, France
| | - Xiangang Zong
- Center for Integrated Protein Science Munich CiPSM and Department of Pharmacy–Center for Drug Research, Ludwig-Maximilians-Universität München, Munich, Germany
| | - Martin Biel
- Center for Integrated Protein Science Munich CiPSM and Department of Pharmacy–Center for Drug Research, Ludwig-Maximilians-Universität München, Munich, Germany
| | - Robert Lukowski
- Department of Pharmacology, Toxicology and Clinical Pharmacy, Institute of Pharmacy
| | - Matthias W. Seeliger
- Division of Ocular Neurodegeneration, Institute for Ophthalmic Research, Centre for Ophthalmology, University of Tübingen, Tübingen, Germany
| | - Stylianos Michalakis
- Center for Integrated Protein Science Munich CiPSM and Department of Pharmacy–Center for Drug Research, Ludwig-Maximilians-Universität München, Munich, Germany
| | - Bernd Wissinger
- Molecular Genetics Laboratory, Institute for Ophthalmic Research, and
| | - Peter Ruth
- Department of Pharmacology, Toxicology and Clinical Pharmacy, Institute of Pharmacy
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13
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Yang F, Ma H, Butler MR, Ding XQ. Deficiency of type 2 iodothyronine deiodinase reduces necroptosis activity and oxidative stress responses in retinas of Leber congenital amaurosis model mice. FASEB J 2018; 32:fj201800484RR. [PMID: 29874126 PMCID: PMC6181634 DOI: 10.1096/fj.201800484rr] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/12/2018] [Accepted: 05/14/2018] [Indexed: 02/06/2023]
Abstract
Thyroid hormone (TH) signaling has been shown to regulate cone photoreceptor viability. Suppression of TH signaling with antithyroid drug treatment or by targeting iodothyronine deiodinases and TH receptors preserves cones in mouse models of retinal degeneration, including the Leber congenital amaurosis Rpe65-deficient mice. This work investigates the cellular mechanisms underlying how suppressing TH signaling preserves cones in Rpe65-deficient mice, using mice deficient in type 2 iodothyronine deiodinase (Dio2), the enzyme that converts the prohormone thyroxine to the active hormone triiodothyronine (T3). Deficiency of Dio2 improved cone survival and function in Rpe65-/- and Rpe65-deficiency on a cone dominant background ( Rpe65-/-/ Nrl-/-) mice. Analysis of cell death pathways revealed that receptor-interacting serine/threonine-protein kinase (RIPK)/necroptosis activity was increased in Rpe65-/-/ Nrl-/- retinas, and Dio2 deficiency reversed the alterations. Cell-stress analysis showed that the cellular oxidative stress responses were increased in Rpe65-/-/ Nrl-/- retinas, and Dio2 deficiency abolished the elevations. Similarly, antithyroid drug treatment resulted in reduced RIPK/necroptosis activity and oxidative stress responses in Rpe65-/-/ Nrl-/- retinas. Moreover, treatment with T3 significantly induced RIPK/necroptosis activity and oxidative stress responses in the retina. This work shows that suppression of TH signaling reduces cellular RIPK/necroptosis activity and oxidative stress responses in degenerating retinas, suggesting a mechanism underlying the observed cone preservation.-Yang, F., Ma, H., Butler, M. R., Ding, X.-Q. Deficiency of type 2 iodothyronine deiodinase reduces necroptosis activity and oxidative stress responses in retinas of Leber congenital amaurosis model mice.
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Affiliation(s)
- Fan Yang
- Department of Cell Biology, University of Oklahoma Health Sciences Center, Oklahoma City, Oklahoma, USA
| | - Hongwei Ma
- Department of Cell Biology, University of Oklahoma Health Sciences Center, Oklahoma City, Oklahoma, USA
| | - Michael R. Butler
- Department of Cell Biology, University of Oklahoma Health Sciences Center, Oklahoma City, Oklahoma, USA
| | - Xi-Qin Ding
- Department of Cell Biology, University of Oklahoma Health Sciences Center, Oklahoma City, Oklahoma, USA
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14
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Abstract
The first step in vision is the absorption of photons by the photopigments in cone and rod photoreceptors. After initial amplification within the phototransduction cascade the signal is translated into an electrical signal by the action of cyclic nucleotide-gated (CNG) channels. CNG channels are ligand-gated ion channels that are activated by the binding of cyclic guanosine monophosphate (cGMP) or cyclic adenosine monophosphate (cAMP). Retinal CNG channels transduce changes in intracellular concentrations of cGMP into changes of the membrane potential and the Ca2+ concentration. Structurally, the CNG channels belong to the superfamily of pore-loop cation channels and share a common gross structure with hyperpolarization-activated cyclic nucleotide-gated (HCN) channels and voltage-gated potassium channels (KCN). In this review, we provide an overview on the molecular properties of CNG channels and describe their physiological role in the phototransduction pathways. We also discuss insights into the pathophysiological role of CNG channel proteins that have emerged from the analysis of CNG channel-deficient animal models and human CNG channelopathies. Finally, we summarize recent gene therapy activities and provide an outlook for future clinical application.
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Affiliation(s)
- Stylianos Michalakis
- Center for Integrated Protein Science Munich (CIPSM), Department of Pharmacy-Center for Drug Research, Ludwig-Maximilians-Universität München, Butenandtstr, 5-13, 81377 Munich, Germany.
| | - Elvir Becirovic
- Center for Integrated Protein Science Munich (CIPSM), Department of Pharmacy-Center for Drug Research, Ludwig-Maximilians-Universität München, Butenandtstr, 5-13, 81377 Munich, Germany.
| | - Martin Biel
- Center for Integrated Protein Science Munich (CIPSM), Department of Pharmacy-Center for Drug Research, Ludwig-Maximilians-Universität München, Butenandtstr, 5-13, 81377 Munich, Germany.
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15
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Michalakis S, Schön C, Becirovic E, Biel M. Gene therapy for achromatopsia. J Gene Med 2018; 19. [PMID: 28095637 DOI: 10.1002/jgm.2944] [Citation(s) in RCA: 28] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/23/2016] [Revised: 01/13/2017] [Accepted: 01/13/2017] [Indexed: 02/02/2023] Open
Abstract
The present review summarizes the current status of achromatopsia (ACHM) gene therapy-related research activities and provides an outlook for their clinical application. ACHM is an inherited eye disease characterized by a congenital absence of cone photoreceptor function. As a consequence, ACHM is associated with strongly impaired daylight vision, photophobia, nystagmus and a lack of color discrimination. Currently, six genes have been linked to ACHM. Up to 80% of the patients carry mutations in the genes CNGA3 and CNGB3 encoding the two subunits of the cone cyclic nucleotide-gated channel. Various animal models of the disease have been established and their characterization has helped to increase our understanding of the pathophysiology associated with ACHM. With the advent of adeno-associated virus vectors as valuable gene delivery tools for retinal photoreceptors, a number of promising gene supplementation therapy programs have been initiated. In recent years, huge progress has been made towards bringing a curative treatment for ACHM into clinics. The first clinical trials are ongoing or will be launched soon and are expected to contribute important data on the safety and efficacy of ACHM gene supplementation therapy.
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Affiliation(s)
- Stylianos Michalakis
- Center for Integrated Protein Science Munich CiPSM and Department of Pharmacy - Center for Drug Research, Ludwig-Maximilians-Universität München, Munich, Germany
| | - Christian Schön
- Center for Integrated Protein Science Munich CiPSM and Department of Pharmacy - Center for Drug Research, Ludwig-Maximilians-Universität München, Munich, Germany
| | - Elvir Becirovic
- Center for Integrated Protein Science Munich CiPSM and Department of Pharmacy - Center for Drug Research, Ludwig-Maximilians-Universität München, Munich, Germany
| | - Martin Biel
- Center for Integrated Protein Science Munich CiPSM and Department of Pharmacy - Center for Drug Research, Ludwig-Maximilians-Universität München, Munich, Germany
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16
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Singh RK, Mallela RK, Hayes A, Dunham NR, Hedden ME, Enke RA, Fariss RN, Sternberg H, West MD, Nasonkin IO. Dnmt1, Dnmt3a and Dnmt3b cooperate in photoreceptor and outer plexiform layer development in the mammalian retina. Exp Eye Res 2017; 159:132-146. [PMID: 27865785 DOI: 10.1016/j.exer.2016.11.014] [Citation(s) in RCA: 30] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/07/2016] [Revised: 10/21/2016] [Accepted: 11/14/2016] [Indexed: 11/18/2022]
Abstract
Characterizing the role of epigenetic regulation in the mammalian retina is critical for understanding fundamental mechanisms of retinal development and disease. DNA methylation, an epigenetic modifier of genomic DNA, plays an important role in modulating networks of tissue and cell-specific gene expression. However, the impact of DNA methylation on retinal development and homeostasis of retinal neurons remains unclear. Here, we have created a tissue-specific DNA methyltransferase (Dnmt) triple mutant mouse in an effort to characterize the impact of DNA methylation on retinal development and homeostasis. An Rx-Cre transgene was used to drive targeted mutation of all three murine Dnmt genes in the mouse retina encoding major DNA methylation enzymes DNMT1, DNMT3A and DNMT3B. The triple mutant mice represent a hypomorph model since Dnmt1 catalytic activity was still present and excision of Dnmt3a and Dnmt3b had only about 90% efficiency. Mutation of all three Dnmts resulted in global genomic hypomethylation and dramatic reorganization of the photoreceptor and synaptic layers within retina. Transcriptome and proteomic analyses demonstrated enrichment of dysregulated phototransduction and synaptic genes. The 5 mC signal in triple mutant retina was confined to the central heterochromatin but reduced in the peripheral heterochromatin region of photoreceptor nuclei. In addition, we found a reduction of the 5 mC signal in ganglion cell nuclei. Collectively, this data suggests cooperation of all three Dnmts in the formation and homeostasis of photoreceptors and other retinal neurons within the mammalian retina, and highlight the relevance of epigenetic regulation to sensory retinal disorders and vision loss.
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Affiliation(s)
- Ratnesh K Singh
- Department of Ophthalmology, University of Pittsburgh Medical School, USA.
| | - Ramya K Mallela
- Department of Ophthalmology, University of Pittsburgh Medical School, USA
| | - Abigail Hayes
- Department of Ophthalmology, West Virginia University, USA
| | | | | | - Raymond A Enke
- Department of Biology, James Madison University, USA; Center for Genome and Metagenome Studies, James Madison University, USA
| | - Robert N Fariss
- Biological Imaging Core, National Eye Institute, Bethesda, MD 20892, USA
| | - Hal Sternberg
- BioTime, 1010 Atlantic Avenue, Alameda, CA 94501, USA
| | | | - Igor O Nasonkin
- Department of Ophthalmology, University of Pittsburgh Medical School, USA.
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17
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Butler MR, Ma H, Yang F, Belcher J, Le YZ, Mikoshiba K, Biel M, Michalakis S, Iuso A, Križaj D, Ding XQ. Endoplasmic reticulum (ER) Ca 2+-channel activity contributes to ER stress and cone death in cyclic nucleotide-gated channel deficiency. J Biol Chem 2017; 292:11189-11205. [PMID: 28495882 DOI: 10.1074/jbc.m117.782326] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/21/2017] [Revised: 05/01/2017] [Indexed: 02/05/2023] Open
Abstract
Endoplasmic reticulum (ER) stress and mislocalization of improperly folded proteins have been shown to contribute to photoreceptor death in models of inherited retinal degenerative diseases. In particular, mice with cone cyclic nucleotide-gated (CNG) channel deficiency, a model for achromatopsia, display both early-onset ER stress and opsin mistrafficking. By 2 weeks of age, these mice show elevated signaling from all three arms of the ER-stress pathway, and by 1 month, cone opsin is improperly distributed away from its normal outer segment location to other retinal layers. This work investigated the role of Ca2+-release channels in ER stress, protein mislocalization, and cone death in a mouse model of CNG-channel deficiency. We examined whether preservation of luminal Ca2+ stores through pharmacological and genetic suppression of ER Ca2+ efflux protects cones by attenuating ER stress. We demonstrated that the inhibition of ER Ca2+-efflux channels reduced all three arms of ER-stress signaling while improving opsin trafficking to cone outer segments and decreasing cone death by 20-35%. Cone-specific gene deletion of the inositol-1,4,5-trisphosphate receptor type I (IP3R1) also significantly increased cone density in the CNG-channel-deficient mice, suggesting that IP3R1 signaling contributes to Ca2+ homeostasis and cone survival. Consistent with the important contribution of organellar Ca2+ signaling in this achromatopsia mouse model, significant differences in dynamic intraorganellar Ca2+ levels were detected in CNG-channel-deficient cones. These results thus identify a novel molecular link between Ca2+ homeostasis and cone degeneration, thereby revealing novel therapeutic targets to preserve cones in inherited retinal degenerative diseases.
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Affiliation(s)
| | | | - Fan Yang
- From the Departments of Cell Biology
| | | | - Yun-Zheng Le
- From the Departments of Cell Biology.,Internal Medicine, and.,Ophthalmology and.,the Harold Hamm Diabetes Center, University of Oklahoma Health Sciences Center, Oklahoma City, Oklahoma 73104
| | - Katsuhiko Mikoshiba
- the Laboratory for Developmental Neurobiology, RIKEN Brain Science Institute, Hirosawa Wako-shi, Saitama 351-0198, Japan
| | - Martin Biel
- the Center for Integrated Protein Science Munich (CIPSM) and Department of Pharmacy, Center for Drug Research, Ludwig-Maximilians-Universität München, 81377 Munich, Germany, and
| | - Stylianos Michalakis
- the Center for Integrated Protein Science Munich (CIPSM) and Department of Pharmacy, Center for Drug Research, Ludwig-Maximilians-Universität München, 81377 Munich, Germany, and
| | - Anthony Iuso
- the John A. Moran Eye Center, University of Utah, Salt Lake City, Utah 84132
| | - David Križaj
- the John A. Moran Eye Center, University of Utah, Salt Lake City, Utah 84132
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18
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Ma H, Yang F, Butler MR, Belcher J, Redmond TM, Placzek AT, Scanlan TS, Ding XQ. Inhibition of thyroid hormone receptor locally in the retina is a therapeutic strategy for retinal degeneration. FASEB J 2017; 31:3425-3438. [PMID: 28428265 DOI: 10.1096/fj.201601166rr] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/25/2016] [Accepted: 04/11/2017] [Indexed: 12/22/2022]
Abstract
Thyroid hormone (TH) signaling regulates cell proliferation, differentiation, and metabolism. Recent studies have implicated TH signaling in cone photoreceptor viability. Using mouse models of retinal degeneration, we demonstrated that antithyroid drug treatment and targeting iodothyronine deiodinases (DIOs) to suppress cellular tri-iodothyronine (T3) production or increase T3 degradation preserves cones. In this work, we investigated the effectiveness of inhibition of the TH receptor (TR). Two genes, THRA and THRB, encode TRs; THRB2 has been associated with cone viability. Using TR antagonists and Thrb2 deletion, we examined the effects of TR inhibition. Systemic and ocular treatment with the TR antagonists NH-3 and 1-850 increased cone density by 30-40% in the Rpe65-/- mouse model of Leber congenital amaurosis and reduced the number of TUNEL+ cells. Cone survival was significantly improved in Rpe65-/- and Cpfl1 (a model of achromatopsia with Pde6c defect) mice with Thrb2 deletion. Ventral cone density in Cpfl1/Thrb2-/- and Rpe65-/- /Thrb2-/- mice was increased by 1- to 4-fold, compared with age-matched controls. Moreover, the expression levels of TR were significantly higher in the cone-degeneration retinas, suggesting locally elevated TR signaling. This work shows that the effects of antithyroid treatment or targeting DIOs were likely mediated by TRs and that suppressing TR protects cones. Our findings support the view that inhibition of TR locally in the retina is a therapeutic strategy for retinal degeneration management.-Ma, H., Yang, F., Butler, M. R., Belcher, J., Redmond, T. M., Placzek, A. T., Scanlan, T. S., Ding, X.-Q. Inhibition of thyroid hormone receptor locally in the retina is a therapeutic strategy for retinal degeneration.
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Affiliation(s)
- Hongwei Ma
- Department of Cell Biology, University of Oklahoma Health Sciences Center, Oklahoma City, Oklahoma, USA
| | - Fan Yang
- Department of Cell Biology, University of Oklahoma Health Sciences Center, Oklahoma City, Oklahoma, USA
| | - Michael R Butler
- Department of Cell Biology, University of Oklahoma Health Sciences Center, Oklahoma City, Oklahoma, USA
| | - Joshua Belcher
- Department of Cell Biology, University of Oklahoma Health Sciences Center, Oklahoma City, Oklahoma, USA
| | - T Michael Redmond
- Laboratory of Retinal Cell and Molecular Biology, National Eye Institute, National Institutes of Health, Bethesda, Maryland, USA
| | - Andrew T Placzek
- Department of Physiology and Pharmacology, Oregon Health and Science University, Portland, Oregon, USA
| | - Thomas S Scanlan
- Department of Physiology and Pharmacology, Oregon Health and Science University, Portland, Oregon, USA
| | - Xi-Qin Ding
- Department of Cell Biology, University of Oklahoma Health Sciences Center, Oklahoma City, Oklahoma, USA;
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Yang F, Ma H, Belcher J, Butler MR, Redmond TM, Boye SL, Hauswirth WW, Ding XQ. Targeting iodothyronine deiodinases locally in the retina is a therapeutic strategy for retinal degeneration. FASEB J 2016; 30:4313-4325. [PMID: 27623928 DOI: 10.1096/fj.201600715r] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/28/2016] [Accepted: 09/01/2016] [Indexed: 12/21/2022]
Abstract
Recent studies have implicated thyroid hormone (TH) signaling in cone photoreceptor viability. Using mouse models of retinal degeneration, we found that antithyroid treatment preserves cones. This work investigates the significance of targeting intracellular TH components locally in the retina. The cellular TH level is mainly regulated by deiodinase iodothyronine (DIO)-2 and -3. DIO2 converts thyroxine (T4) to triiodothyronine (T3), which binds to the TH receptor, whereas DIO3 degrades T3 and T4. We examined cone survival after overexpression of DIO3 and inhibition of DIO2 and demonstrated the benefits of these manipulations. Subretinal delivery of AAV5-IRBP/GNAT2-DIO3, which directs expression of human DIO3 specifically in cones, increased cone density by 30-40% in a Rpe65-/- mouse model of Lebers congenital amaurosis (LCA) and in a Cpfl1 mouse with Pde6c defect model of achromatopsia, compared with their respective untreated controls. Intravitreal and topical delivery of the DIO2 inhibitor iopanoic acid also significantly improved cone survival in the LCA model mice. Moreover, the expression levels of DIO2 and Slc16a2 were significantly higher in the diseased retinas, suggesting locally elevated TH signaling. We show that targeting DIOs protects cones, and intracellular inhibition of TH components locally in the retina may represent a novel strategy for retinal degeneration management.-Yang, F., Ma, H., Belcher, J., Butler, M. R., Redmond, T. M., Boye, S. L., Hauswirth, W. W., Ding, X.-Q. Targeting iodothyronine deiodinases locally in the retina is a therapeutic strategy for retinal degeneration.
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Affiliation(s)
- Fan Yang
- Department of Cell Biology, University of Oklahoma Health Sciences Center, Oklahoma City, Oklahoma, USA
| | - Hongwei Ma
- Department of Cell Biology, University of Oklahoma Health Sciences Center, Oklahoma City, Oklahoma, USA
| | - Joshua Belcher
- Department of Cell Biology, University of Oklahoma Health Sciences Center, Oklahoma City, Oklahoma, USA
| | - Michael R Butler
- Department of Cell Biology, University of Oklahoma Health Sciences Center, Oklahoma City, Oklahoma, USA
| | - T Michael Redmond
- Laboratory of Retinal Cell and Molecular Biology, National Eye Institute, Bethesda, Maryland, USA
| | - Sanford L Boye
- Department of Ophthalmology, University of Florida, Gainesville, Florida, USA; and.,Department of Molecular Genetics and Microbiology, University of Florida, Gainesville, Florida, USA
| | - William W Hauswirth
- Department of Ophthalmology, University of Florida, Gainesville, Florida, USA; and.,Department of Molecular Genetics and Microbiology, University of Florida, Gainesville, Florida, USA
| | - Xi-Qin Ding
- Department of Cell Biology, University of Oklahoma Health Sciences Center, Oklahoma City, Oklahoma, USA;
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Ding XQ, Thapa A, Ma H, Xu J, Elliott MH, Rodgers KK, Smith ML, Wang JS, Pittler SJ, Kefalov VJ. The B3 Subunit of the Cone Cyclic Nucleotide-gated Channel Regulates the Light Responses of Cones and Contributes to the Channel Structural Flexibility. J Biol Chem 2016; 291:8721-34. [PMID: 26893377 DOI: 10.1074/jbc.m115.696138] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/03/2015] [Indexed: 11/06/2022] Open
Abstract
Cone photoreceptor cyclic nucleotide-gated (CNG) channels play a pivotal role in cone phototransduction, which is a process essential for daylight vision, color vision, and visual acuity. Mutations in the cone channel subunits CNGA3 and CNGB3 are associated with human cone diseases, including achromatopsia, cone dystrophies, and early onset macular degeneration. Mutations in CNGB3 alone account for 50% of reported cases of achromatopsia. This work investigated the role of CNGB3 in cone light response and cone channel structural stability. As cones comprise only 2-3% of the total photoreceptor population in the wild-type mouse retina, we used Cngb3(-/-)/Nrl(-/-) mice with CNGB3 deficiency on a cone-dominant background in our study. We found that, in the absence of CNGB3, CNGA3 was able to travel to the outer segments, co-localize with cone opsin, and form tetrameric complexes. Electroretinogram analyses revealed reduced cone light response amplitude/sensitivity and slower response recovery in Cngb3(-/-)/Nrl(-/-) mice compared with Nrl(-/-) mice. Absence of CNGB3 expression altered the adaptation capacity of cones and severely compromised function in bright light. Biochemical analysis demonstrated that CNGA3 channels lacking CNGB3 were more resilient to proteolysis than CNGA3/CNGB3 channels, suggesting a hindered structural flexibility. Thus, CNGB3 regulates cone light response kinetics and the channel structural flexibility. This work advances our understanding of the biochemical and functional role of CNGB3 in cone photoreceptors.
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Affiliation(s)
| | | | - Hongwei Ma
- From the Departments of Cell Biology and
| | - Jianhua Xu
- From the Departments of Cell Biology and
| | - Michael H Elliott
- Ophthalmology and Dean McGee Eye Institute, Oklahoma City, Oklahoma 73104
| | - Karla K Rodgers
- Biochemistry, University of Oklahoma Health Sciences Center and
| | - Marci L Smith
- Department of Vision Sciences, University of Alabama, Birmingham, Alabama 35924, and
| | - Jin-Shan Wang
- Department of Ophthalmology and Visual Sciences, Washington University School of Medicine, Saint Louis, Missouri 63110
| | - Steven J Pittler
- Department of Vision Sciences, University of Alabama, Birmingham, Alabama 35924, and
| | - Vladimir J Kefalov
- Department of Ophthalmology and Visual Sciences, Washington University School of Medicine, Saint Louis, Missouri 63110
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Marangoni D, Vijayasarathy C, Bush RA, Wei LL, Wen R, Sieving PA. Intravitreal Ciliary Neurotrophic Factor Transiently Improves Cone-Mediated Function in a CNGB3-/- Mouse Model of Achromatopsia. Invest Ophthalmol Vis Sci 2016; 56:6810-22. [PMID: 26567794 DOI: 10.1167/iovs.15-16866] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022] Open
Abstract
PURPOSE Ciliary neurotrophic factor (CNTF) was recently shown to augment cone function in CNGB3 mutant achromat dogs. However, testing CNTF-releasing implant in human CNGB3 achromats failed to show benefit. We evaluated the effects of CNTF protein on the retinal function in an additional achromatopsia model, the CNGB3-/- mouse. METHODS Fifty-nine CNGB3-/- mice (postnatal day [PD] ± SD = 30 ± 7) received a unilateral intravitreal injection of 1 or 2 μg CNTF protein, and 15 wild-type (WT) mice (PD = 34 ± 3) received 1 μg CNTF. Retinal function was evaluated by flash ERG and photopic flicker ERG (fERG) at 7 and 14 days after treatment. RESULTS Seven days post CNTF, the photopic b-wave Vmax was significantly increased in CNGB3-/- mice (P < 0.01), whereas it was reduced in WT mice (P < 0.05). Ciliary neurotrophic factor significantly increased the amplitude of photopic fERG and the photopic oscillatory potentials (OPs) in CNGB3-/- mice. Ciliary neurotrophic factor did not alter the scotopic a-wave in either CNGB3-/- or WT mice, but it increased the scotopic b-wave k (P < 0.01) in CNGB3-/- mice, indicating diminished scotopic sensitivity, and reduced the scotopic b-wave Vmax in WT mice (P < 0.05). No difference was found in ERG parameters between 1 or 2 μg CNTF. Fourteen days after CNTF injection the ERG changes in CNGB3-/- mice were lost. CONCLUSIONS Intravitreal bolus CNTF protein caused a small and transient improvement of cone-mediated function in CNGB3-/- mice, whereas it reduced rod-mediated function. The increase in photopic OPs and the lack of changes in scotopic a-wave suggest a CNTF effect on the inner retina.
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Affiliation(s)
- Dario Marangoni
- National Institute on Deafness and Other Communication Disorders, National Institutes of Health, Bethesda, Maryland, United States 3Department of Biotechnology and Applied Clinical Science, University of L'Aquila, L'Aquila, Italy
| | - Camasamudram Vijayasarathy
- National Institute on Deafness and Other Communication Disorders, National Institutes of Health, Bethesda, Maryland, United States
| | - Ronald A Bush
- National Institute on Deafness and Other Communication Disorders, National Institutes of Health, Bethesda, Maryland, United States
| | - Lisa L Wei
- National Eye Institute, National Institutes of Health, Bethesda, Maryland, United States
| | - Rong Wen
- Bascom Palmer Eye Institute, Department of Ophthalmology, University of Miami, Miller School of Medicine, Miami, Florida, United States
| | - Paul A Sieving
- National Institute on Deafness and Other Communication Disorders, National Institutes of Health, Bethesda, Maryland, United States 2National Eye Institute, National Institutes of Health, Bethesda, Maryland, United States
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22
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Understanding Cone Photoreceptor Cell Death in Achromatopsia. RETINAL DEGENERATIVE DISEASES 2016; 854:231-6. [DOI: 10.1007/978-3-319-17121-0_31] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
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23
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Giblin JP, Comes N, Strauss O, Gasull X. Ion Channels in the Eye: Involvement in Ocular Pathologies. ADVANCES IN PROTEIN CHEMISTRY AND STRUCTURAL BIOLOGY 2015; 104:157-231. [PMID: 27038375 DOI: 10.1016/bs.apcsb.2015.11.006] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
The eye is the sensory organ of vision. There, the retina transforms photons into electrical signals that are sent to higher brain areas to produce visual sensations. In the light path to the retina, different types of cells and tissues are involved in maintaining the transparency of avascular structures like the cornea or lens, while others, like the retinal pigment epithelium, have a critical role in the maintenance of photoreceptor function by regenerating the visual pigment. Here, we have reviewed the roles of different ion channels expressed in ocular tissues (cornea, conjunctiva and neurons innervating the ocular surface, lens, retina, retinal pigment epithelium, and the inflow and outflow systems of the aqueous humor) that are involved in ocular disease pathophysiologies and those whose deletion or pharmacological modulation leads to specific diseases of the eye. These include pathologies such as retinitis pigmentosa, macular degeneration, achromatopsia, glaucoma, cataracts, dry eye, or keratoconjunctivitis among others. Several disease-associated ion channels are potential targets for pharmacological intervention or other therapeutic approaches, thus highlighting the importance of these channels in ocular physiology and pathophysiology.
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Affiliation(s)
- Jonathan P Giblin
- Universitat de Barcelona, Barcelona, Spain; Institut d'Investigacions Biomèdiques August Pi i Sunyer (IDIBAPS), Barcelona, Spain
| | - Nuria Comes
- Universitat de Barcelona, Barcelona, Spain; Institut d'Investigacions Biomèdiques August Pi i Sunyer (IDIBAPS), Barcelona, Spain
| | | | - Xavier Gasull
- Universitat de Barcelona, Barcelona, Spain; Institut d'Investigacions Biomèdiques August Pi i Sunyer (IDIBAPS), Barcelona, Spain.
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24
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Vinberg F, Wang T, Molday RS, Chen J, Kefalov VJ. A new mouse model for stationary night blindness with mutant Slc24a1 explains the pathophysiology of the associated human disease. Hum Mol Genet 2015; 24:5915-29. [PMID: 26246500 DOI: 10.1093/hmg/ddv319] [Citation(s) in RCA: 28] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/05/2015] [Accepted: 07/31/2015] [Indexed: 11/12/2022] Open
Abstract
Mutations that affect calcium homeostasis (Ca(2+)) in rod photoreceptors are linked to retinal degeneration and visual disorders such as retinitis pigmentosa and congenital stationary night blindness (CSNB). It is thought that the concentration of Ca(2+) in rod outer segments is controlled by a dynamic balance between influx via cGMP-gated (CNG) channels and extrusion via Na(+)/Ca(2+), K(+) exchangers (NCKX1). The extrusion-driven lowering of rod [Ca(2+)]i following light exposure controls their light adaptation and response termination. Mutant NCKX1 has been linked to autosomal-recessive stationary night blindness. However, whether NCKX1 contributes to light adaptation has not been directly tested and the mechanisms by which human NCKX1 mutations cause night blindness are not understood. Here, we report that the deletion of NCKX1 in mice results in malformed outer segment disks, suppressed expression and function of rod CNG channels and a subsequent 100-fold reduction in rod responses, while preserving normal cone responses. The compensating loss of CNG channel function in the absence of NCKX1-mediated Ca(2+) extrusion may prevent toxic Ca(2+) buildup and provides an explanation for the stationary nature of the associated disorder in humans. Surprisingly, the lack of NCKX1 did not compromise rod background light adaptation, suggesting additional Ca(2+)-extruding mechanisms exist in these cells.
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Affiliation(s)
- Frans Vinberg
- Ophthalmology and Visual Sciences, Washington University School of Medicine, St. Louis, MO, USA
| | - Tian Wang
- Cell and Neurobiology, Zilkha Neurogenetic Institute, University of Southern California, Los Angeles, CA, USA and
| | - Robert S Molday
- Biochemistry/Molecular Biology, University of British Columbia, Vancouver, Canada
| | - Jeannie Chen
- Cell and Neurobiology, Zilkha Neurogenetic Institute, University of Southern California, Los Angeles, CA, USA and
| | - Vladimir J Kefalov
- Ophthalmology and Visual Sciences, Washington University School of Medicine, St. Louis, MO, USA,
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25
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Ma H, Butler MR, Thapa A, Belcher J, Yang F, Baehr W, Biel M, Michalakis S, Ding XQ. cGMP/Protein Kinase G Signaling Suppresses Inositol 1,4,5-Trisphosphate Receptor Phosphorylation and Promotes Endoplasmic Reticulum Stress in Photoreceptors of Cyclic Nucleotide-gated Channel-deficient Mice. J Biol Chem 2015; 290:20880-20892. [PMID: 26124274 DOI: 10.1074/jbc.m115.641159] [Citation(s) in RCA: 32] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/27/2015] [Indexed: 11/06/2022] Open
Abstract
Photoreceptor cyclic nucleotide-gated (CNG) channels play a pivotal role in phototransduction. Mutations in the cone CNG channel subunits CNGA3 and CNGB3 are associated with achromatopsia and cone dystrophies. We have shown endoplasmic reticulum (ER) stress-associated apoptotic cone death and increased phosphorylation of the ER Ca(2+) channel inositol 1,4,5-trisphosphate receptor 1 (IP3R1) in CNG channel-deficient mice. We also presented a remarkable elevation of cGMP and an increased activity of the cGMP-dependent protein kinase (protein kinase G, PKG) in CNG channel deficiency. This work investigated whether cGMP/PKG signaling regulates ER stress and IP3R1 phosphorylation in CNG channel-deficient cones. Treatment with PKG inhibitor and deletion of guanylate cyclase-1 (GC1), the enzyme producing cGMP in cones, were used to suppress cGMP/PKG signaling in cone-dominant Cnga3(-/-)/Nrl(-/-) mice. We found that treatment with PKG inhibitor or deletion of GC1 effectively reduced apoptotic cone death, increased expression levels of cone proteins, and decreased activation of Müller glial cells. Furthermore, we observed significantly increased phosphorylation of IP3R1 and reduced ER stress. Our findings demonstrate a role of cGMP/PKG signaling in ER stress and ER Ca(2+) channel regulation and provide insights into the mechanism of cone degeneration in CNG channel deficiency.
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Affiliation(s)
- Hongwei Ma
- Department of Cell Biology, University of Oklahoma Health Sciences Center, Oklahoma City, Oklahoma 73104
| | - Michael R Butler
- Department of Cell Biology, University of Oklahoma Health Sciences Center, Oklahoma City, Oklahoma 73104
| | - Arjun Thapa
- Department of Cell Biology, University of Oklahoma Health Sciences Center, Oklahoma City, Oklahoma 73104
| | - Josh Belcher
- Department of Cell Biology, University of Oklahoma Health Sciences Center, Oklahoma City, Oklahoma 73104
| | - Fan Yang
- Department of Cell Biology, University of Oklahoma Health Sciences Center, Oklahoma City, Oklahoma 73104
| | - Wolfgang Baehr
- John A. Moran Eye Center, University of Utah, Salt Lake City, Utah 84132
| | - Martin Biel
- Center for Integrated Protein Science Munich and Department of Pharmacy, Center for Drug Research, Ludwig-Maximilians-Universität München, 81377 Munich, Germany
| | - Stylianos Michalakis
- Center for Integrated Protein Science Munich and Department of Pharmacy, Center for Drug Research, Ludwig-Maximilians-Universität München, 81377 Munich, Germany
| | - Xi-Qin Ding
- Department of Cell Biology, University of Oklahoma Health Sciences Center, Oklahoma City, Oklahoma 73104.
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26
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Banin E, Gootwine E, Obolensky A, Ezra-Elia R, Ejzenberg A, Zelinger L, Honig H, Rosov A, Yamin E, Sharon D, Averbukh E, Hauswirth WW, Ofri R. Gene Augmentation Therapy Restores Retinal Function and Visual Behavior in a Sheep Model of CNGA3 Achromatopsia. Mol Ther 2015; 23:1423-33. [PMID: 26087757 DOI: 10.1038/mt.2015.114] [Citation(s) in RCA: 81] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/05/2015] [Accepted: 06/05/2015] [Indexed: 12/15/2022] Open
Abstract
Achromatopsia is a hereditary form of day blindness caused by cone photoreceptor dysfunction. Affected patients suffer from congenital color blindness, photosensitivity, and low visual acuity. Mutations in the CNGA3 gene are a major cause of achromatopsia, and a sheep model of this disease was recently characterized by our group. Here, we report that unilateral subretinal delivery of an adeno-associated virus serotype 5 (AAV5) vector carrying either the mouse or the human intact CNGA3 gene under the control of the red/green opsin promoter results in long-term recovery of visual function in CNGA3-mutant sheep. Treated animals demonstrated shorter maze passage times and a reduced number of collisions with obstacles compared with their pretreatment status, with values close to those of unaffected sheep. This effect was abolished when the treated eye was patched. Electroretinography (ERG) showed marked improvement in cone function. Retinal expression of the transfected human and mouse CNGA3 genes at the mRNA level was shown by polymerase chain reaction (PCR), and cone-specific expression of CNGA3 protein was demonstrated by immunohistochemisrty. The rescue effect has so far been maintained for over 3 years in the first-treated animals, with no obvious ocular or systemic side effects. The results support future application of subretinal AAV5-mediated gene-augmentation therapy in CNGA3 achromatopsia patients.
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Affiliation(s)
- Eyal Banin
- Department of Ophthalmology, Hadassah-Hebrew University Medical Center, Jerusalem, Israel
| | - Elisha Gootwine
- Agricultural Research Organization, The Volcani Center, Bet Dagan, Israel
| | - Alexey Obolensky
- Department of Ophthalmology, Hadassah-Hebrew University Medical Center, Jerusalem, Israel
| | - Raaya Ezra-Elia
- Koret School of Veterinary Medicine, Hebrew University of Jerusalem, Rehovot, Israel
| | - Ayala Ejzenberg
- Department of Ophthalmology, Hadassah-Hebrew University Medical Center, Jerusalem, Israel
| | - Lina Zelinger
- Department of Ophthalmology, Hadassah-Hebrew University Medical Center, Jerusalem, Israel
| | - Hen Honig
- Agricultural Research Organization, The Volcani Center, Bet Dagan, Israel
| | - Alexander Rosov
- Agricultural Research Organization, The Volcani Center, Bet Dagan, Israel
| | - Esther Yamin
- Department of Ophthalmology, Hadassah-Hebrew University Medical Center, Jerusalem, Israel
| | - Dror Sharon
- Department of Ophthalmology, Hadassah-Hebrew University Medical Center, Jerusalem, Israel
| | - Edward Averbukh
- Department of Ophthalmology, Hadassah-Hebrew University Medical Center, Jerusalem, Israel
| | - William W Hauswirth
- Department of Ophthalmology, University of Florida, Gainesville, Florida, USA
| | - Ron Ofri
- Koret School of Veterinary Medicine, Hebrew University of Jerusalem, Rehovot, Israel
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27
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Zein WM, Jeffrey BG, Wiley HE, Turriff AE, Tumminia SJ, Tao W, Bush RA, Marangoni D, Wen R, Wei LL, Sieving PA. CNGB3-achromatopsia clinical trial with CNTF: diminished rod pathway responses with no evidence of improvement in cone function. Invest Ophthalmol Vis Sci 2014; 55:6301-8. [PMID: 25205868 DOI: 10.1167/iovs.14-14860] [Citation(s) in RCA: 38] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022] Open
Abstract
PURPOSE Ciliary neurotrophic factor (CNTF) protects rod photoreceptors from retinal degenerative disease in multiple nonhuman models. Thus far, CNTF has failed to demonstrate rod protection in trials for human retinitis pigmentosa. Recently, CNTF was found to improve cone photoreceptor function in a canine CNGB3 achromatopsia model. This study explores whether this finding translates to humans with CNGB3 achromatopsia. METHODS A five-subject, open-label Phase I/II study was initiated by implanting intraocular microcapsules releasing CNTF (nominally 20 ng/d) into one eye each of CNGB3 achromat participants. Fellow eyes served as untreated controls. Subjects were followed for 1 year. RESULTS Pupil constriction in treated eyes gave evidence of intraocular CNTF release. Additionally, scotopic ERG responses were reduced, and dark-adapted psychophysical absolute thresholds were increased, attributable to diminished rod or rod pathway activity. Optical coherence tomography revealed that the cone-rich fovea underwent structural changes as the foveal hyporeflective zone (HRZ) became diminished in CNTF-treated eyes. No objectively measurable enhancement of cone function was found by assessments of visual acuity, mesopic increment sensitivity threshold, or the photopic ERG. Careful measurements of color hue discrimination showed no change. Nonetheless, subjects reported beneficial changes of visual function in the treated eyes, including reduced light sensitivity and aversion to bright light, which may trace to decreased effective ambient light from the pupillary constriction; further they noted slowed adaptation to darkness, consistent with CNTF action on rod photoreceptors. CONCLUSIONS Ciliary neurotrophic factor did not measurably enhance cone function, which reveals a species difference between human and canine CNGB3 cones in response to CNTF. (ClinicalTrials.gov number, NCT01648452.).
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Affiliation(s)
- Wadih M Zein
- National Eye Institute, National Institutes of Health, Bethesda, Maryland, United States
| | - Brett G Jeffrey
- National Eye Institute, National Institutes of Health, Bethesda, Maryland, United States
| | - Henry E Wiley
- National Eye Institute, National Institutes of Health, Bethesda, Maryland, United States
| | - Amy E Turriff
- National Eye Institute, National Institutes of Health, Bethesda, Maryland, United States
| | - Santa J Tumminia
- National Eye Institute, National Institutes of Health, Bethesda, Maryland, United States
| | - Weng Tao
- Neurotech Pharmaceuticals, Inc., Cumberland, Rhode Island, United States
| | - Ronald A Bush
- National Institute on Deafness and Other Communication Disorders, National Institutes of Health, Bethesda, Maryland, United States
| | - Dario Marangoni
- National Institute on Deafness and Other Communication Disorders, National Institutes of Health, Bethesda, Maryland, United States Department of Biotechnology and Applied Clinical Science, University of L'Aquila, L'Aquila, Italy
| | - Rong Wen
- Bascom Palmer Eye Institute, Department of Ophthalmology, University of Miami, Miller School of Medicine, Miami, Florida, United States
| | - Lisa L Wei
- National Eye Institute, National Institutes of Health, Bethesda, Maryland, United States
| | - Paul A Sieving
- National Eye Institute, National Institutes of Health, Bethesda, Maryland, United States National Institute on Deafness and Other Communication Disorders, National Institutes of Health, Bethesda, Maryland, United States
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Suppressing thyroid hormone signaling preserves cone photoreceptors in mouse models of retinal degeneration. Proc Natl Acad Sci U S A 2014; 111:3602-7. [PMID: 24550448 DOI: 10.1073/pnas.1317041111] [Citation(s) in RCA: 36] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022] Open
Abstract
Cone phototransduction and survival of cones in the human macula is essential for color vision and for visual acuity. Progressive cone degeneration in age-related macular degeneration, Stargardt disease, and recessive cone dystrophies is a major cause of blindness. Thyroid hormone (TH) signaling, which regulates cell proliferation, differentiation, and apoptosis, plays a central role in cone opsin expression and patterning in the retina. Here, we investigated whether TH signaling affects cone viability in inherited retinal degeneration mouse models. Retinol isomerase RPE65-deficient mice [a model of Leber congenital amaurosis (LCA) with rapid cone loss] and cone photoreceptor function loss type 1 mice (severe recessive achromatopsia) were used to determine whether suppressing TH signaling with antithyroid treatment reduces cone death. Further, cone cyclic nucleotide-gated channel B subunit-deficient mice (moderate achromatopsia) and guanylate cyclase 2e-deficient mice (LCA with slower cone loss) were used to determine whether triiodothyronine (T3) treatment (stimulating TH signaling) causes deterioration of cones. We found that cone density in retinol isomerase RPE65-deficient and cone photoreceptor function loss type 1 mice increased about sixfold following antithyroid treatment. Cone density in cone cyclic nucleotide-gated channel B subunit-deficient and guanylate cyclase 2e-deficient mice decreased about 40% following T3 treatment. The effect of TH signaling on cone viability appears to be independent of its regulation on cone opsin expression. This work demonstrates that suppressing TH signaling in retina dystrophy mouse models is protective of cones, providing insights into cone preservation and therapeutic interventions.
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29
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cGMP accumulation causes photoreceptor degeneration in CNG channel deficiency: evidence of cGMP cytotoxicity independently of enhanced CNG channel function. J Neurosci 2013; 33:14939-48. [PMID: 24027293 DOI: 10.1523/jneurosci.0909-13.2013] [Citation(s) in RCA: 57] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
Photoreceptor cyclic nucleotide-gated (CNG) channels regulate Ca(2+) influx in rod and cone photoreceptors. cGMP, the native ligand of the photoreceptor CNG channels, has been associated with cytotoxicity when its levels rise above normal due to defects in photoreceptor phosphodiesterase (PDE6) or regulation of retinal guanylyl cyclase (retGC). We found a massive accumulation of cGMP in CNGA3-deficient retina and investigated whether cGMP accumulation plays a role in cone degeneration in CNG channel deficiency. The time course study showed that the retinal cGMP level in Cnga3(-/-);Nrl(-/-) mice with CNGA3 deficiency on a cone-dominant background was sharply increased at postnatal day 8 (P8), peaked around P10-P15, remained high through P30-P60, and returned to near control level at P90. This elevation pattern correlated with photoreceptor apoptotic death, which peaked around P15-P20. In Cnga3(-/-);Gucy2e(-/-) mice lacking retGC1, cone density and expression levels of cone-specific proteins were significantly increased compared with Cnga3(-/-), consistent with a role of cGMP accumulation as the major contributor to cone death caused by CNG channel deficiency. The activity and expression levels of cGMP-dependent protein kinase G (PKG) were significantly increased in Cnga3(-/-);Nrl(-/-) retina compared with Nrl(-/-), suggesting an involvement of PKG regulation in cell death. Our results indicate that cGMP accumulation in photoreceptors can itself exert cytotoxic effect in cones, independently of CNG channel activity and Ca(2+) influx.
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Schön C, Biel M, Michalakis S. Gene replacement therapy for retinal CNG channelopathies. Mol Genet Genomics 2013; 288:459-67. [DOI: 10.1007/s00438-013-0766-4] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/28/2013] [Accepted: 06/25/2013] [Indexed: 12/20/2022]
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Ma H, Thapa A, Morris LM, Michalakis S, Biel M, Frank MB, Bebak M, Ding XQ. Loss of cone cyclic nucleotide-gated channel leads to alterations in light response modulating system and cellular stress response pathways: a gene expression profiling study. Hum Mol Genet 2013; 22:3906-19. [PMID: 23740940 DOI: 10.1093/hmg/ddt245] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/17/2023] Open
Abstract
The cone photoreceptor cyclic nucleotide-gated (CNG) channel is essential for central and color vision and visual acuity. Mutations in the channel subunits CNGA3 and CNGB3 are associated with achromatopsia and cone dystrophy. We investigated the gene expression profiles in mouse retina with CNG channel deficiency using whole genome expression microarrays. As cones comprise only 2 to 3% of the total photoreceptor population in the wild-type mouse retina, the mouse lines with CNG channel deficiency on a cone-dominant background, i.e. Cnga3-/-/Nrl-/- and Cngb3-/-/Nrl-/- mice, were used in our study. Comparative data analysis revealed a total of 105 genes altered in Cnga3-/-/Nrl-/- and 92 in Cngb3-/-/Nrl-/- retinas, relative to Nrl-/- retinas, with 27 genes changed in both genotypes. The differentially expressed genes primarily encode proteins associated with cell signaling, cellular function maintenance and gene expression. Ingenuity pathway analysis (IPA) identified 26 and 9 canonical pathways in Cnga3-/-/Nrl-/- and Cngb3-/-/Nrl-/- retinas, respectively, with 6 pathways being shared. The shared pathways include phototransduction, cAMP/PKA-mediated signaling, endothelin signaling, and EIF2/endoplasmic reticulum (ER) stress, whereas the IL-1, CREB, and purine metabolism signaling were found to specifically associate with Cnga3 deficiency. Thus, CNG channel deficiency differentially regulates genes that affect cell processes such as phototransduction, cellular survival and gene expression, and such regulations play a crucial role(s) in the retinal adaptation to impaired cone phototransduction. Though lack of Cnga3 and Cngb3 shares many common pathways, deficiency of Cnga3 causes more significant alterations in gene expression. This work provides insights into how cones respond to impaired phototransduction at the gene expression levels.
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Abstract
Mammalian cones respond to light by closing a cGMP-gated channel via a cascade that includes a heterotrimeric G-protein, cone transducin, comprising Gαt2, Gβ3 and Gγt2 subunits. The function of Gβγ in this cascade has not been examined. Here, we investigate the role of Gβ3 by assessing cone structure and function in Gβ3-null mouse (Gnb3(-/-)). We found that Gβ3 is required for the normal expression of its partners, because in the Gnb3(-/-) cone outer segments, the levels of Gαt2 and Gγt2 are reduced by fourfold to sixfold, whereas other components of the cascade remain unaltered. Surprisingly, Gnb3(-/-) cones produce stable responses with normal kinetics and saturating response amplitudes similar to that of the wild-type, suggesting that cone phototransduction can function efficiently without a Gβ subunit. However, light sensitivity was reduced by approximately fourfold in the knock-out cones. Because the reduction in sensitivity was similar in magnitude to the reduction in Gαt2 level in the cone outer segment, we conclude that activation of Gαt2 in Gnb3(-/-) cones proceeds at a rate approximately proportional to its outer segment concentration, and that activation of phosphodiesterase and downstream cascade components is normal. These results suggest that the main role of Gβ3 in cones is to establish optimal levels of transducin heteromer in the outer segment, thereby indirectly contributing to robust response properties.
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Pang JJ, Lei L, Dai X, Shi W, Liu X, Dinculescu A, McDowell JH. AAV-mediated gene therapy in mouse models of recessive retinal degeneration. Curr Mol Med 2012; 12:316-30. [PMID: 22300136 DOI: 10.2174/156652412799218877] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/28/2011] [Revised: 08/23/2011] [Accepted: 10/25/2011] [Indexed: 02/01/2023]
Abstract
In recent years, more and more mutant genes that cause retinal diseases have been detected. At the same time, many naturally occurring mouse models of retinal degeneration have also been found, which show similar changes to human retinal diseases. These, together with improved viral vector quality allow more and more traditionally incurable inherited retinal disorders to become potential candidates for gene therapy. Currently, the most common vehicle to deliver the therapeutic gene into target retinal cells is the adenoassociated viral vector (AAV). Following delivery to the immuno-privileged subretinal space, AAV-vectors can efficiently target both retinal pigment epithelium and photoreceptor cells, the origin of most retinal degenerations. This review focuses on the AAV-based gene therapy in mouse models of recessive retinal degenerations, especially those in which delivery of the correct copy of the wild-type gene has led to significant beneficial effects on visual function, as determined by morphological, biochemical, electroretinographic and behavioral analysis. The past studies in animal models and ongoing successful LCA2 clinical trials, predict a bright future for AAV gene replacement treatment for inherited recessive retinal diseases.
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Affiliation(s)
- J-J Pang
- Eye Hospital, School of Ophthalmology & Optometry, Wenzhou Medical College, China.
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Ji Y, Zhu CL, Grzywacz NM, Lee EJ. Rearrangement of the cone mosaic in the retina of the rat model of retinitis pigmentosa. J Comp Neurol 2012; 520:874-88. [PMID: 22102145 DOI: 10.1002/cne.22800] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Abstract
In retinitis pigmentosa (RP), the death of cones normally follows some time after the degeneration of rods. Recently, surviving cones in RP have been studied and reported in detail. These cones undergo extensive remodeling in their morphology. Here we report an extension of the remodeling study to consider possible modifications of spatial-distribution patterns. For this purpose we used S334ter-line-3 transgenic rats, a transgenic model developed to express a rhodopsin mutation causing RP. In this study, retinas were collected at postnatal (P) days P5-30, 90, 180, and P600. We then immunostained the retinas to examine the morphology and distribution of cones and to quantify the total cone numbers. Our results indicate that cones undergo extensive changes in their spatial distribution to give rise to a mosaic comprising an orderly array of rings. These rings first begin to appear at P15 at random regions of the retina and become ubiquitous throughout the entire tissue by P90. Such distribution pattern loses its clarity by P180 and mostly disappears at P600, at which time the cones are almost all dead. In contrast, the numbers of cones in RP and normal conditions do not show significant differences at stages as late as P180. Therefore, rings do not form by cell death at their centers, but by cone migration. We discuss its possible mechanisms and suggest a role for hot spots of rod death and the remodeling of Müller cell process into zones of low density of photoreceptors.
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Affiliation(s)
- Yerina Ji
- Neuroscience Graduate Program, University of Southern California, Los Angeles, California 90089-1111, USA
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Thapa A, Morris L, Xu J, Ma H, Michalakis S, Biel M, Ding XQ. Endoplasmic reticulum stress-associated cone photoreceptor degeneration in cyclic nucleotide-gated channel deficiency. J Biol Chem 2012; 287:18018-29. [PMID: 22493484 DOI: 10.1074/jbc.m112.342220] [Citation(s) in RCA: 44] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Cyclic nucleotide-gated (CNG) channels play a pivotal role in phototransduction. Mutations in the cone CNG channel subunits CNGA3 and CNGB3 account for >70% of all known cases of achromatopsia. Cones degenerate in achromatopsia patients and in CNGA3(-/-) and CNGB3(-/-) mice. This work investigates the molecular basis of cone degeneration in CNG channel deficiency. As cones comprise only 2-3% of the total photoreceptor population in the wild-type mouse retina, we generated mouse lines with CNG channel deficiency on a cone-dominant background, i.e. CNGA3(-/-)/Nrl(-/-) and CNGB3(-/-)/Nrl(-/-) mice. The retinal phenotype and potential cell death pathways were examined by functional, biochemical, and immunohistochemical approaches. CNGA3(-/-)/Nrl(-/-) and CNGB3(-/-)/Nrl(-/-) mice showed impaired cone function, opsin mislocalization, and cone degeneration similar to that in the single knock-out mice. The endoplasmic reticulum stress marker proteins, including Grp78/Bip, phospho-eIF2α, phospho-IP(3)R, and CCAAT/enhancer-binding protein homologous protein, were elevated significantly in CNGA3(-/-)/Nrl(-/-) and CNGB3(-/-)/Nrl(-/-) retinas, compared with the age-matched (postnatal 30 days) Nrl(-/-) controls. Along with these, up-regulation of the cysteine protease calpains and cleavage of caspase-12 and caspase-7 were found in the channel-deficient retinas, suggesting an endoplasmic reticulum stress-associated apoptosis. In addition, we observed a nuclear translocation of apoptosis-inducing factor (AIF) and endonuclease G in CNGA3(-/-)/Nrl(-/-) and CNGB3(-/-)/Nrl(-/-) retinas, implying a mitochondrial insult in the endoplasmic reticulum stress-activated cell death process. Taken together, our findings suggest a crucial role of endoplasmic reticulum stress in cone degeneration associated with CNG channel deficiency.
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Affiliation(s)
- Arjun Thapa
- Department of Cell Biology, University of Oklahoma Health Sciences Center, Oklahoma City, Oklahoma 73104, USA
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Xu J, Morris LM, Michalakis S, Biel M, Fliesler SJ, Sherry DM, Ding XQ. CNGA3 deficiency affects cone synaptic terminal structure and function and leads to secondary rod dysfunction and degeneration. Invest Ophthalmol Vis Sci 2012; 53:1117-29. [PMID: 22247469 DOI: 10.1167/iovs.11-8168] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022] Open
Abstract
PURPOSE To investigate rod function and survival after cone dysfunction and degeneration in a mouse model of cone cyclic nucleotide-gated (CNG) channel deficiency. METHODS Rod function and survival in mice with cone CNG channel subunit CNGA3 deficiency (CNGA3-/- mice) were evaluated by electroretinographic (ERG), morphometric, and Western blot analyses. The arrangement, integrity, and ultrastructure of photoreceptor terminals were investigated by immunohistochemistry and electron microscopy. RESULTS The authors found loss of cone function and cone death accompanied by impairment of rods and rod-driven signaling in CNGA3-/- mice. Scotopic ERG b-wave amplitudes were reduced by 15% at 1 month, 30% at 6 months, and 40% at 9 months and older, while scotopic a-wave amplitudes were decreased by 20% at 9 months, compared with ERGs of age-matched wild-type mice. Outer nuclear layer thickness in CNGA3-/- retina was reduced by 15% at 12 months compared with age-matched wild-type controls. This was accompanied by a 30%-40% reduction in expression of rod-specific proteins, including rhodopsin, rod transducin α-subunit, and glutamic acid-rich protein (GARP). Cone terminals in the CNGA3-/- retina showed a progressive loss of neurochemical and ultrastructural integrity. Abnormalities were observed as early as 1 month. Disorganized rod terminal ultrastructure was noted by 12 months. CONCLUSIONS These findings demonstrate secondary rod impairment and degeneration after cone degeneration in mice with cone CNG channel deficiency. Loss of cone phototransduction accompanies the compromised integrity of cone terminals. With time, rod synaptic structure, function, and viability also become compromised.
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Affiliation(s)
- Jianhua Xu
- Department of Cell Biology, The University of Oklahoma Health Sciences Center, Oklahoma City, OK 73104, USA
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Wen R, Tao W, Li Y, Sieving PA. CNTF and retina. Prog Retin Eye Res 2011; 31:136-51. [PMID: 22182585 DOI: 10.1016/j.preteyeres.2011.11.005] [Citation(s) in RCA: 156] [Impact Index Per Article: 12.0] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/02/2011] [Revised: 10/29/2011] [Accepted: 11/17/2011] [Indexed: 11/15/2022]
Abstract
Ciliary neurotrophic factor (CNTF) is one of the most studied neurotrophic factors for neuroprotection of the retina. A large body of evidence demonstrates that CNTF promotes rod photoreceptor survival in almost all animal models. Recent studies indicate that CNTF also promotes cone photoreceptor survival and cone outer segment regeneration in the degenerating retina and improves cone function in dogs with congenital achromotopsia. In addition, CNTF is a neuroprotective factor and an axogenesis factor for retinal ganglion cells (RGCs). This review focuses on the effects of exogenous CNTF on photoreceptors and RGCs in the mammalian retina and the potential clinical application of CNTF for retinal degenerative diseases.
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Affiliation(s)
- Rong Wen
- Bascom Palmer Eye Institute, University of Miami, Miller School of Medicine, Miami, FL 33136, USA.
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Carvalho LS, Xu J, Pearson RA, Smith AJ, Bainbridge JW, Morris LM, Fliesler SJ, Ding XQ, Ali RR. Long-term and age-dependent restoration of visual function in a mouse model of CNGB3-associated achromatopsia following gene therapy. Hum Mol Genet 2011; 20:3161-75. [PMID: 21576125 PMCID: PMC3140821 DOI: 10.1093/hmg/ddr218] [Citation(s) in RCA: 133] [Impact Index Per Article: 10.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022] Open
Abstract
Mutations in the CNGB3 gene account for >50% of all known cases of achromatopsia. Although of early onset, its stationary character and the potential for rapid assessment of restoration of retinal function following therapy renders achromatopsia a very attractive candidate for gene therapy. Here we tested the efficacy of an rAAV2/8 vector containing a human cone arrestin promoter and a human CNGB3 cDNA in CNGB3 deficient mice. Following subretinal delivery of the vector, CNGB3 was detected in both M- and S-cones and resulted in increased levels of CNGA3, increased cone density and survival, improved cone outer segment structure and normal subcellular compartmentalization of cone opsins. Therapy also resulted in long-term improvement of retinal function, with restoration of cone ERG amplitudes of up to 90% of wild-type and a significant improvement in visual acuity. Remarkably, successful restoration of cone function was observed even when treatment was initiated at 6 months of age; however, restoration of normal visual acuity was only possible in younger animals (e.g. 2–4 weeks old). This study represents achievement of the most substantial restoration of visual function reported to date in an animal model of achromatopsia using a human gene construct, which has the potential to be utilized in clinical trials.
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Affiliation(s)
- Livia S Carvalho
- The Department of Genetics, UCL Institute of Ophthalmology, London, UK
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