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1.
Am J Pathol ; 193(11): 1706-1720, 2023 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-36328299

RESUMO

A pathologic feature of late-onset retinal degeneration caused by the S163R mutation in C1q-tumor necrosis factor-5 (C1QTNF5) is the presence of unusually thick deposits between the retinal pigmented epithelium (RPE) and the vascular choroid, considered a hallmark of this disease. Following its specific expression in mouse RPE, the S163R mutant exhibits a reversed polarized distribution relative to the apically secreted wild-type C1QTNF5, and forms widespread, prominent deposits that gradually increase in size with aging. The current study shows that S163R deposits expand to a considerable thickness through a progressive increase in the basolateral RPE membrane, substantially raising the total RPE height, and enabling their clear imaging as a distinct hyporeflective layer by noninvasive optical coherence tomography in advanced age animals. This phenotype bears a striking resemblance to ocular pathology previously documented in patients harboring the S163R mutation. Therefore, a similar viral vector-based gene delivery approach was used to also investigate the behavior of P188T and G216C, two novel pathogenic C1QTNF5 mutants recently reported in patients for which histopathologic data are lacking. Both mutants primarily impacted the RPE/photoreceptor interface and did not generate basal laminar deposits. Distinct distribution patterns and phenotypic consequences of C1QTNF5 mutants were observed in vivo, which suggested that multiple pathobiological mechanisms contribute to RPE dysfunction and vision loss in this disorder.


Assuntos
Degeneração Retiniana , Humanos , Camundongos , Animais , Degeneração Retiniana/patologia , Mutação , Epitélio Pigmentado da Retina/metabolismo , Fenótipo
2.
FASEB J ; 35(10): e21927, 2021 10.
Artigo em Inglês | MEDLINE | ID: mdl-34547123

RESUMO

Cone photoreceptors are responsible for the visual acuity and color vision of the human eye. Red/green cone opsin missense mutations N94K, W177R, P307L, R330Q, and G338E have been identified in subjects with congenital blue cone monochromacy or color-vision deficiency. Studies on disease mechanisms due to these cone opsin mutations have been previously carried out exclusively in vitro, and the reported impairments were not always consistent. Here we expressed these mutants via AAV specifically in vivo in M-opsin knockout mouse cones to investigate their subcellular localization, the pathogenic effects on cone structure, function, and cone viability. We show that these mutations alter the M-opsin structure, function, and localization. N94K and W177R mutants appeared to be misfolded since they localized exclusively in cone inner segments and endoplasmic reticulum. In contrast, P307L, R330Q, and G338E mutants were detected predominately in cone outer segments. Expression of R330Q and G338E, but not P307L opsins, also partially restored expression and correct localization of cone PDE6α' and cone transducin γ and resulted in partial rescue of M-cone-mediated light responses. Expression of W177R and P307L mutants significantly reduced cone viability, whereas N94K, R330Q, and G338E were only modestly toxic. We propose that although the underlying biochemical and cellular defects caused by these mutants are distinct, they all seem to exhibit a dominant phenotype, resembling autosomal dominant retinitis pigmentosa associated with the majority of rhodopsin missense mutations. The understanding of the molecular mechanisms associated with these cone opsin mutants is fundamental to developing targeted therapies for cone dystrophy/dysfunction.


Assuntos
Distrofia de Cones/genética , Opsinas dos Cones/genética , Genes Ligados ao Cromossomo X , Mutação de Sentido Incorreto/genética , Animais , Feminino , Humanos , Masculino , Camundongos , Retinose Pigmentar/genética , Rodopsina/genética , Opsinas de Bastonetes/genética
3.
Proc Natl Acad Sci U S A ; 116(10): 4496-4501, 2019 03 05.
Artigo em Inglês | MEDLINE | ID: mdl-30782832

RESUMO

Autosomal recessive genetic forms (DFNB) account for most cases of profound congenital deafness. Adeno-associated virus (AAV)-based gene therapy is a promising therapeutic option, but is limited by a potentially short therapeutic window and the constrained packaging capacity of the vector. We focus here on the otoferlin gene underlying DFNB9, one of the most frequent genetic forms of congenital deafness. We adopted a dual AAV approach using two different recombinant vectors, one containing the 5' and the other the 3' portions of otoferlin cDNA, which exceed the packaging capacity of the AAV when combined. A single delivery of the vector pair into the mature cochlea of Otof-/- mutant mice reconstituted the otoferlin cDNA coding sequence through recombination of the 5' and 3' cDNAs, leading to the durable restoration of otoferlin expression in transduced cells and a reversal of the deafness phenotype, raising hopes for future gene therapy trials in DFNB9 patients.


Assuntos
Surdez/terapia , Dependovirus/genética , Terapia Genética , Proteínas de Membrana/genética , Animais , Surdez/genética , Modelos Animais de Doenças , Vetores Genéticos , Humanos , Camundongos , Camundongos Endogâmicos C57BL , Camundongos Transgênicos
4.
J Pathol ; 250(2): 195-204, 2020 02.
Artigo em Inglês | MEDLINE | ID: mdl-31625146

RESUMO

Usher syndrome type 3 (USH3) is an autosomal recessively inherited disorder caused by mutations in the gene clarin-1 (CLRN1), leading to combined progressive hearing loss and retinal degeneration. The cellular distribution of CLRN1 in the retina remains uncertain, either because its expression levels are low or because its epitopes are masked. Indeed, in the adult mouse retina, Clrn1 mRNA is developmentally downregulated, detectable only by RT-PCR. In this study we used the highly sensitive RNAscope in situ hybridization assay and single-cell RNA-sequencing techniques to investigate the distribution of Clrn1 and CLRN1 in mouse and human retina, respectively. We found that Clrn1 transcripts in mouse tissue are localized to the inner retina during postnatal development and in adult stages. The pattern of Clrn1 mRNA cellular expression is similar in both mouse and human adult retina, with CLRN1 transcripts being localized in Müller glia, and not photoreceptors. We generated a novel knock-in mouse with a hemagglutinin (HA) epitope-tagged CLRN1 and showed that CLRN1 is expressed continuously at the protein level in the retina. Following enzymatic deglycosylation and immunoblotting analysis, we detected a single CLRN1-specific protein band in homogenates of mouse and human retina, consistent in size with the main CLRN1 isoform. Taken together, our results implicate Müller glia in USH3 pathology, placing this cell type to the center of future mechanistic and therapeutic studies to prevent vision loss in this disease. © 2019 The Authors. The Journal of Pathology published by John Wiley & Sons Ltd on behalf of Pathological Society of Great Britain and Ireland.


Assuntos
Células Ependimogliais/metabolismo , Proteínas de Membrana/biossíntese , Retina/metabolismo , Síndromes de Usher/metabolismo , Animais , Glicosilação , Humanos , Hibridização In Situ , Proteínas de Membrana/genética , Camundongos Endogâmicos C57BL , Neuroglia/metabolismo , RNA Mensageiro/genética , Síndromes de Usher/patologia
5.
Adv Exp Med Biol ; 1074: 61-66, 2018.
Artigo em Inglês | MEDLINE | ID: mdl-29721928

RESUMO

The pathogenic mutation S163R in C1QTNF5 causes a disorder known as autosomal dominant late-onset retinal degeneration (L-ORD), characterized by the presence of thick extracellular sub-RPE deposits, similar histopathologically to those found in AMD patients. We have previously shown that the S163R C1QTNF5 mutant forms globular aggregates within the RPE in vivo following its AAV-mediated expression in the RPE and exhibits a reversely polarized distribution, being routed toward the basal rather than apical RPE. We show here that when both wild-type and mutant S163R C1QTNF5 are simultaneously delivered subretinally to mouse RPE cells, the mutant impairs the wild-type protein secretion from the RPE, and both proteins are dispersed toward the basal and lateral RPE membrane. This result has mechanistic and therapeutic implications for L-ORD disorder.


Assuntos
Degeneração Macular/genética , Mutação de Sentido Incorreto , Mutação Puntual , Agregação Patológica de Proteínas/genética , Epitélio Pigmentado da Retina/metabolismo , Animais , Polaridade Celular , Colágeno/química , Colágeno/genética , Colágeno/metabolismo , Dependovirus/genética , Eletrorretinografia , Genes Dominantes , Vetores Genéticos , Humanos , Injeções Intraoculares , Degeneração Macular/metabolismo , Degeneração Macular/patologia , Camundongos , Camundongos Endogâmicos C57BL , Agregação Patológica de Proteínas/patologia , Proteínas Recombinantes/análise , Proteínas Recombinantes/metabolismo , Epitélio Pigmentado da Retina/ultraestrutura , Frações Subcelulares/química
6.
Hum Mol Genet ; 24(21): 6229-39, 2015 Nov 01.
Artigo em Inglês | MEDLINE | ID: mdl-26310623

RESUMO

Adeno-associated virus (AAV) effectively targets therapeutic genes to photoreceptors, pigment epithelia, Müller glia and ganglion cells of the retina. To date, no one has shown the ability to correct, with gene replacement, an inherent defect in bipolar cells (BCs), the excitatory interneurons of the retina. Targeting BCs with gene replacement has been difficult primarily due to the relative inaccessibility of BCs to standard AAV vectors. This approach would be useful for restoration of vision in patients with complete congenital stationary night blindness (CSNB1), where signaling through the ON BCs is eliminated due to mutations in their G-protein-coupled cascade genes. For example, the majority of CSNB1 patients carry a mutation in nyctalopin (NYX), which encodes a protein essential for proper localization of the TRPM1 cation channel required for ON BC light-evoked depolarization. As a group, CSNB1 patients have a normal electroretinogram (ERG) a-wave, indicative of photoreceptor function, but lack a b-wave due to defects in ON BC signaling. Despite retinal dysfunction, the retinas of CSNB1 patients do not degenerate. The Nyx(nob) mouse model of CSNB1 faithfully mimics this phenotype. Here, we show that intravitreally injected, rationally designed AAV2(quadY-F+T-V) containing a novel 'Ple155' promoter drives either GFP or YFP_Nyx in postnatal Nyx(nob) mice. In treated Nyx(nob) retina, robust and targeted Nyx transgene expression in ON BCs partially restored the ERG b-wave and, at the cellular level, signaling in ON BCs. Our results support the potential for gene delivery to BCs and gene replacement therapy in human CSNB1.


Assuntos
Dependovirus/genética , Oftalmopatias Hereditárias/genética , Doenças Genéticas Ligadas ao Cromossomo X/genética , Vetores Genéticos , Miopia/genética , Cegueira Noturna/genética , Proteoglicanas/genética , Células Bipolares da Retina/metabolismo , Animais , Modelos Animais de Doenças , Oftalmopatias Hereditárias/metabolismo , Doenças Genéticas Ligadas ao Cromossomo X/metabolismo , Humanos , Injeções Intravítreas , Camundongos , Camundongos Endogâmicos C57BL , Mutação , Miopia/metabolismo , Cegueira Noturna/metabolismo , Regiões Promotoras Genéticas , Retina/metabolismo , Transfecção , Transgenes , Visão Ocular
7.
Adv Exp Med Biol ; 801: 695-701, 2014.
Artigo em Inglês | MEDLINE | ID: mdl-24664760

RESUMO

Achromatopsia (ACHM) is caused by a progressive loss of cone photoreceptors leading to color blindness and poor visual acuity. Animal studies and human clinical trials have shown that gene replacement therapy with adeno-associate virus (AAV) is a viable treatment option for this disease. Although there have been successful attempts to optimize capsid proteins for increased specificity, it is simpler to restrict expression via the use of cell type-specific promoters. To target cone photoreceptors, a chimeric promoter consisting of an enhancer element of interphotoreceptor retinoid-binding protein promoter and a minimal sequence of the human transducin alpha-subunit promoter (IRBPe/GNAT2) was created. Additionally, a synthetic transducin alpha-subunit promoter (synGNAT2/GNAT2) containing conserved sequence blocks located downstream of the transcriptional start was created. The strength and specificity of these promoters were evaluated in murine retina by immunohistochemistry. The results showed that the chimeric, (IRBPe/GNAT2) promoter is more efficient and specific than the synthetic, synGNAT2/GNAT2 promoter. Additionally, IRBPe/GNAT2-mediated expression was found in all cone subtypes and it was improved over existing promoters currently used for gene therapy of achromatopsia.


Assuntos
Defeitos da Visão Cromática/genética , Defeitos da Visão Cromática/terapia , Terapia Genética/métodos , Regiões Promotoras Genéticas/genética , Células Fotorreceptoras Retinianas Cones/fisiologia , Transducina/genética , Animais , Defeitos da Visão Cromática/patologia , Dependovirus/genética , Cães , Proteínas do Olho/genética , Regulação da Expressão Gênica , Humanos , Camundongos , Ratos , Proteínas Recombinantes de Fusão/genética , Células Fotorreceptoras Retinianas Cones/patologia , Proteínas de Ligação ao Retinol/genética
8.
Front Neurosci ; 18: 1368089, 2024.
Artigo em Inglês | MEDLINE | ID: mdl-38410159

RESUMO

Long-and middle-wavelength cone photoreceptors, which are responsible for our visual acuity and color vision, comprise ~95% of our total cone population and are concentrated in the fovea of our retina. Previously, we characterized the disease mechanisms of the L/M-cone opsin missense mutations N94K, W177R, P307L, R330Q and G338E, all of which are associated with congenital blue cone monochromacy (BCM) or color-vision deficiency. Here, we used a similar viral vector-based gene delivery approach in M-opsin knockout mice to investigate the pathogenic consequences of the BCM or color-vision deficient associated L-cone opsin (OPN1LW) mutants K82E, P187S, and M273K. We investigated their subcellular localization, the pathogenic effects on cone structure, function, and cone viability. K82E mutants were detected predominately in cone outer segments, and its expression partially restored expression and correct localization of cone PDE6α' and cone transducin γ. As a result, K82E also demonstrated the ability to mediate cone light responses. In contrast, expression of P187S was minimally detected by either western blot or by immunohistochemistry, probably due to efficient degradation of the mutant protein. M273K cone opsin appeared to be misfolded as it was primarily localized to the cone inner segment and endoplasmic reticulum. Additionally, M273K did not restore the expression of cone PDE6α' and cone transducin γ in dorsal cone OS, presumably by its inability to bind 11-cis retinal. Consistent with the observed expression pattern, P187S and M273K cone opsin mutants were unable to mediate light responses. Moreover, expression of K82E, P187S, and M273K mutants reduced cone viability. Due to the distinct expression patterns and phenotypic differences of these mutants observed in vivo, we suggest that the pathobiological mechanisms of these mutants are distinct.

9.
Commun Biol ; 7(1): 1027, 2024 Aug 21.
Artigo em Inglês | MEDLINE | ID: mdl-39169121

RESUMO

The retina is light-sensitive neuronal tissue in the back of the eye. The phospholipid composition of the retina is unique and highly enriched in polyunsaturated fatty acids, including docosahexaenoic fatty acid (DHA). While it is generally accepted that a high DHA content is important for vision, surprisingly little is known about the mechanisms of DHA enrichment in the retina. Furthermore, the biological processes controlled by DHA in the eye remain poorly defined as well. Here, we combined genetic manipulations with lipidomic analysis in mice to demonstrate that acyl-CoA synthetase 6 (Acsl6) serves as a regulator of the unique composition of retinal membranes. Inactivation of Acsl6 reduced the levels of DHA-containing phospholipids, led to progressive loss of light-sensitive rod photoreceptor neurons, attenuated the light responses of these cells, and evoked distinct transcriptional response in the retina involving the Srebf1/2 (sterol regulatory element binding transcription factors 1/2) pathway. This study identifies one of the major enzymes responsible for DHA enrichment in the retinal membranes and introduces a model allowing an evaluation of rod functioning and pathology caused by impaired DHA incorporation/retention in the retina.


Assuntos
Coenzima A Ligases , Fosfolipídeos , Células Fotorreceptoras Retinianas Bastonetes , Animais , Camundongos , Coenzima A Ligases/metabolismo , Coenzima A Ligases/genética , Ácidos Docosa-Hexaenoicos/metabolismo , Camundongos Endogâmicos C57BL , Camundongos Knockout , Fosfolipídeos/metabolismo , Retina/metabolismo , Células Fotorreceptoras Retinianas Bastonetes/metabolismo
10.
Sci Adv ; 9(28): eadd5479, 2023 07 14.
Artigo em Inglês | MEDLINE | ID: mdl-37450596

RESUMO

Proteasomes are the central proteolytic machines that are critical for breaking down most of the damaged and abnormal proteins in human cells. Although universally applicable drugs are not yet available, the stimulation of proteasomal activity is being analyzed as a proof-of-principle strategy to increase cellular resistance to a broad range of proteotoxic stressors. These approaches have included the stimulation of proteasomes through the overexpression of individual proteasome subunits, phosphorylation, or conformational changes induced by small molecules or peptides. In contrast to these approaches, we evaluated a transcription-driven increase in the total proteasome pool to enhance the proteolytic capacity of degenerating retinal neurons. We show that overexpression of nuclear factor erythroid-2-like 1 (Nfe2l1) transcription factor stimulated proteasome biogenesis and activity, improved the clearance of the ubiquitin-proteasomal reporter, and delayed photoreceptor neuron loss in a preclinical mouse model of human blindness caused by misfolded proteins. The findings highlight Nfe2l1 as an emerging therapeutic target to treat neurodegenerative diseases linked to protein misfolding.


Assuntos
Complexo de Endopeptidases do Proteassoma , Fatores de Transcrição , Humanos , Camundongos , Animais , Complexo de Endopeptidases do Proteassoma/metabolismo , Proteólise , Fatores de Transcrição/metabolismo , Ubiquitina/metabolismo , Cegueira
11.
Hum Gene Ther ; 33(13-14): 695-707, 2022 07.
Artigo em Inglês | MEDLINE | ID: mdl-35081746

RESUMO

Glucose metabolism in the retina is carefully orchestrated, with glucose being delivered to photoreceptors from the choroidal circulation through the retinal pigmented epithelium (RPE). In photoreceptors, glucose is processed principally by aerobic glycolysis, from which the lactate byproduct is provided to the RPE and Müller glia for their energetic needs. In this study, we utilize a modified arrestin1 protein to enhance the glycolytic output of lactate from rod photoreceptors through disinhibition of enolase1 activity with the goal being to use this increased lactate production as a gene-agnostic approach to slowing retinal degeneration. Mouse arrestin1 with E362G/D363G amino acid substitutions (referred to as "ArrGG") was packaged into AAV and tested for safety and for efficacy in increasing retinal lactate production. Overexpression of ArrGG in C57BL/6J mice did not result in any detectable changes in either electroretinogram (ERG) function or photoreceptor survival as measured by outer nuclear layer (ONL) thickness. However, mouse retinas expressing ArrGG showed a ∼25% increase in the rate of lactate secretion. Therefore, AAV-ArrGG was delivered intravitreally to heterozygous P23H rhodopsin knockin mice (RhoP23H/+) to determine if enhancing glycolysis in photoreceptors can slow retinal degeneration in this animal model of retinitis pigmentosa. We found that the expression of ArrGG in these mice slowed the decline of both scotopic and photopic ERG function. Correspondingly, there was significant preservation of ONL thickness in RhoP23H/+ mice treated with ArrGG compared with controls. In conclusion, our studies show that expressing ArrGG in C57BL/6J mouse retina results in an increase in lactate production, consistent with an upregulation of glycolysis. In the P23H rhodopsin model of retinitis pigmentosa, the expression of ArrGG led to significant preservation of photoreceptor function and slowing of retinal degeneration. These findings suggest that enhancing glycolysis by targeting increased enolase1 activity with a modified arrestin1 in photoreceptors may offer a therapeutic approach to slowing retinal degeneration.


Assuntos
Degeneração Retiniana , Retinose Pigmentar , Animais , Arrestinas , Modelos Animais de Doenças , Eletrorretinografia , Glucose , Ácido Láctico , Camundongos , Camundongos Endogâmicos C57BL , Retina/metabolismo , Degeneração Retiniana/genética , Degeneração Retiniana/metabolismo , Degeneração Retiniana/terapia , Retinose Pigmentar/terapia , Rodopsina/genética
12.
Hum Gene Ther ; 33(13-14): 708-718, 2022 07.
Artigo em Inglês | MEDLINE | ID: mdl-35272502

RESUMO

Blue cone monochromacy (BCM) is a congenital vision disorder affecting both middle-wavelength (M) and long-wavelength (L) cone photoreceptors of the human retina. BCM results from abolished expression of green and red light-sensitive visual pigments expressed in M- and L-cones, respectively. Previously, we showed that gene augmentation therapy to deliver either human L- or M-opsin rescues dorsal M-opsin dominant cone photoreceptors structurally and functionally in treated M-opsin knockout (Opn1mw-/-) mice. Although Opn1mw-/- mice represent a disease model for BCM patients with deletion mutations, at the cellular level, dorsal cones of Opn1mw-/- mice still express low levels of S-opsin, which are different from L- and M-cones of BCM patients carrying a congenital opsin deletion. To determine whether BCM cones lacking complete opsin expression from birth would benefit from AAV-mediated gene therapy, we evaluated the outcome of gene therapy, and determined the therapeutic window and longevity of rescue in a mouse model lacking both M- and S-opsin (Opn1mw-/-/Opn1sw-/-). Our data show that cones of Opn1mw-/-/Opn1sw-/- mice are viable at younger ages but undergo rapid degeneration. AAV-mediated expression of human L-opsin promoted cone outer segment regeneration and rescued cone-mediated function when mice were injected subretinally at 2 months of age or younger. Cone-mediated function and visually guided behavior were maintained for at least 8 months post-treatment. However, when mice were treated at 5 and 7 months of age, the chance and effectiveness of rescue was significantly reduced, although cones were still present in the retina. Crossing Opn1mw-/-/Opn1sw-/- mice with proteasomal activity reporter mice (UbG76V-GFP) did not reveal GFP accumulation in Opn1mw-/-/Opn1sw-/- cones eliminating impaired degradation of ubiquitinated proteins as stress factor contributing to cone loss. Our results demonstrate that AAV-mediated gene augmentation therapy can rescue cone structure and function in a mouse model with a congenital opsin deletion, but also emphasize the importance that early intervention is crucial for successful therapy.


Assuntos
Defeitos da Visão Cromática , Animais , Defeitos da Visão Cromática/genética , Defeitos da Visão Cromática/terapia , Modelos Animais de Doenças , Terapia Genética/métodos , Humanos , Camundongos , Opsinas/genética , Opsinas/metabolismo , Células Fotorreceptoras Retinianas Cones/metabolismo , Opsinas de Bastonetes/genética , Deleção de Sequência
13.
Biochemistry ; 49(35): 7439-47, 2010 Sep 07.
Artigo em Inglês | MEDLINE | ID: mdl-20669900

RESUMO

RP2 is a ubiquitously expressed protein encoded by a gene associated with X-linked retinitis pigmentosa (XLRP), a retinal degenerative disease that causes severe vision loss. Previous in vitro studies have shown that RP2 binds to ADP ribosylation factor-like 3 (Arl3) and activates its intrinsic GTPase activity, but the function of RP2 in the retina, and in particular photoreceptor cells, remains unclear. To begin to define the role of RP2 in the retina and XLRP, we have conducted biochemical studies to identify proteins in retinal cell extracts that interact with RP2. Here, we show that RP2 interacts with N-ethylmaleimide sensitive factor (NSF) in retinal cells as well as cultured embryonic kidney (HEK293) cells by mass spectrometry-based proteomics and biochemical analysis. This interaction is mediated by the N-terminal domain of NSF. The E138G and DeltaI137 mutations of RP2 known to cause XLRP abolished the interaction of RP2 with the N-terminal domain of NSF. Immunofluorescence labeling studies further showed that RP2 colocalized with NSF in photoreceptors and other cells of the retina. Intense punctate staining of RP2 was observed close to the junction between the inner and outer segments beneath the connecting cilium, as well as within the synaptic region of rod and cone photoreceptors. Our studies indicate that RP2, in addition to serving as a regulator of Arl3, interacts with NSF, and this complex may play an important role in membrane protein trafficking in photoreceptors and other cells of the retina.


Assuntos
Proteínas do Olho/metabolismo , Peptídeos e Proteínas de Sinalização Intracelular/metabolismo , Proteínas de Membrana/metabolismo , Proteínas Sensíveis a N-Etilmaleimida/metabolismo , Células Fotorreceptoras de Vertebrados/metabolismo , Animais , Bovinos , Células Cultivadas , Cílios/metabolismo , Proteínas do Olho/análise , Imunofluorescência , Proteínas de Ligação ao GTP , Humanos , Peptídeos e Proteínas de Sinalização Intracelular/análise , Espectrometria de Massas , Proteínas de Membrana/análise , Camundongos , Proteínas Sensíveis a N-Etilmaleimida/análise , Retina/metabolismo , Retinose Pigmentar/metabolismo , Transfecção
14.
Hum Gene Ther ; 30(11): 1361-1370, 2019 11.
Artigo em Inglês | MEDLINE | ID: mdl-31418294

RESUMO

Autosomal recessive Stargardt disease is the most common inherited macular degeneration in humans. It is caused by mutations in the retina-specific ATP binding cassette transporter A4 (ABCA4) that is essential for the clearance of all-trans-retinal from photoreceptor cells. Loss of this function results in the accumulation of toxic bisretinoids in the outer segment disk membranes and their subsequent transfer into adjacent retinal pigment epithelium (RPE) cells. This ultimately leads to the Stargardt disease phenotype of increased retinal autofluorescence and progressive RPE and photoreceptor cell loss. Adeno-associated virus (AAV) vectors have been widely used in gene therapeutic applications, but their limited cDNA packaging capacity of ∼4.5 kb has impeded their use for transgenes exceeding this limit. AAV dual vectors were developed to overcome this size restriction. In this study, we have evaluated the in vitro expression of ABCA4 using three options: overlap, transplicing, and hybrid ABCA4 dual vector systems. The hybrid system was the most efficient of these dual vector alternatives and used to express the full-length ABCA4 in Abca4-/- mice. The full-length ABCA4 protein correctly localized to photoreceptor outer segments. Moreover, treatment of Abca4-/- mice with this ABCA4 hybrid dual vector system resulted in a reduced accumulation of the lipofuscin/N-retinylidene-N-retinylethanolamine (A2E) autofluorescence in vivo, and retinal A2E quantification supported these findings. These results show that the hybrid AAV dual vector option is both safe and therapeutic in mice, and the delivered ABCA4 transgene is functional and has a significant effect on reducing A2E accumulation in the Abca4-/- mouse model of Stargardt disease.


Assuntos
Transportadores de Cassetes de Ligação de ATP/genética , Transportadores de Cassetes de Ligação de ATP/uso terapêutico , Dependovirus/genética , Genes Recessivos , Vetores Genéticos/metabolismo , Retina/patologia , Doença de Stargardt/genética , Doença de Stargardt/terapia , Animais , Modelos Animais de Doenças , Fluorescência , Fundo de Olho , Células HEK293 , Humanos , Camundongos Endogâmicos C57BL , Retina/metabolismo , Retinoides/metabolismo
15.
Biochemistry ; 47(35): 9098-106, 2008 Sep 02.
Artigo em Inglês | MEDLINE | ID: mdl-18690710

RESUMO

RS1, also known as retinoschisin, is an extracellular discoidin domain-containing protein that has been implicated in maintaining the cellular organization and synaptic structure of the vertebrate retina. Mutations in the gene encoding RS1 are responsible for X-linked retinoschisis, a retinal degenerative disease characterized by the splitting of the retinal cell layers and visual impairment. To better understand the role of RS1 in retinal cell biology and X-linked retinoschisis, we have studied the interaction of wild-type and mutant RS1 with various carbohydrates coupled to agarose supports. RS1 bound efficiently to galactose-agarose and to a lesser extent lactose-agarose, but not agarose, N-acetylgalactosamine-agarose, N-acetylglucosamine-agarose, mannose-agarose, or heparin-agarose. RS1 cysteine mutants (C59S/C223S and C59S/C223S/C40S) which prevent disulfide-linked octamer formation exhibited little if any binding to galactose-agarose. The disease-causing R141H mutant bound galactose-agarose at levels similar to that of wild-type RS1, whereas the R141S mutant resulted in a marked reduction in the level of galactose-agarose binding. RS1 bound to galactose-agarose could be effectively displaced by incubation with isopropyl beta- d-1-thiogalactopyranoside (IPTG). This property was used as a basis to develop an efficient purification procedure. Anion exchange and galactose affinity chromatography was used to purify RS1 from the culture media of stably transformed Sf21 insect cells that express and secrete RS1. This cell expression and protein purification method should prove useful in the isolation of RS1 for detailed structure-function studies.


Assuntos
Proteínas do Olho/isolamento & purificação , Proteínas do Olho/metabolismo , Galactose/metabolismo , Lectinas/química , Proteínas de Protozoários/química , Animais , Sítios de Ligação , Células Cultivadas , Discoidinas , Proteínas do Olho/química , Humanos , Estrutura Terciária de Proteína
16.
Invest Ophthalmol Vis Sci ; 48(6): 2491-7, 2007 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-17525175

RESUMO

PURPOSE: X-linked retinoschisis (XLRS) is an early-onset retinal disease caused by mutations in retinoschisin (RS1), a multisubunit, extracellular protein implicated in retinal cell adhesion. Delivery of the normal RS1 gene to photoreceptors of retinoschisin-deficient mice results in prolonged protein expression and rescue of retinal structure and function. However, most persons with XLRS harbor a missense mutation in the RS1 gene leading to expression of a nonfunctional protein. The purpose of this study was to examine the effect that coexpression of wild-type RS1 with disease-causing mutants has on RS1 expression, oligomerization, and secretion to further evaluate gene therapy as a possible treatment for XLRS. METHODS: RS1 mutants (C59S, D158N, C142W, C142S, T185K, R141H, R141G) were individually expressed or coexpressed with myc-tagged wild-type RS1 (myc-RS1) in EBNA293 cells. Protein expression, secretion, and subunit assembly of wild-type and mutant RS1 were analyzed by Western blotting and coimmunoprecipitation. Immunofluorescence was used to examine the cellular distribution of RS1. RESULTS: Myc-RS1 was identical to untagged, wild-type RS1 with respect to cellular localization, disulfide-linked octamer formation, and secretion. In coexpression studies, myc-RS1 assembled into a disulfide-linked octameric complex and was secreted from cells independent of all disease-linked RS1 mutants studied except the R141H mutant. CONCLUSIONS: When wild-type RS1 is expressed in the same cells as disease-causing mutants, the wild-type protein undergoes protein folding, subunit assembly, and secretion independent of all disease-causing RS1 mutants studied except R141H. These studies suggest that gene therapy may be an effective treatment for most persons with XLRS.


Assuntos
Proteínas do Olho/genética , Expressão Gênica/fisiologia , Terapia Genética , Mutação de Sentido Incorreto , Retinosquise/genética , Animais , Western Blotting , Células COS , Técnicas de Cultura de Células , Chlorocebus aethiops , Antígenos Nucleares do Vírus Epstein-Barr/genética , Proteínas do Olho/metabolismo , Imunoprecipitação , Microscopia de Fluorescência , Mutagênese Sítio-Dirigida , Células Fotorreceptoras de Vertebrados/metabolismo , Dobramento de Proteína , Retinosquise/metabolismo , Transfecção
17.
Vision Res ; 46(22): 3845-52, 2006 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-16884758

RESUMO

A 52-year-old subject harboring an RS1 gene W112C mutation presented with a prominent and asymmetric tapetal-like retinal sheen. Transient ERG responses were smaller and slower in the eye with the more extensive sheen, an association that, to our knowledge, had not been previously reported. An ON-pathway dysfunction explained the abnormalities of the transient but not those of the flicker ERGs. Although in vitro studies showed that the W112C mutant retinoschisin is present only in the cellular fraction and is not secreted, disease expression was remarkably mild, consistent with the notion of the existence of genetic and/or epigenetic disease modifiers.


Assuntos
Proteínas do Olho/genética , Genes Ligados ao Cromossomo X/genética , Retinosquise/genética , Células Cultivadas , Eletrorretinografia/métodos , Angiofluoresceinografia/métodos , Humanos , Masculino , Pessoa de Meia-Idade , Mutação de Sentido Incorreto/genética , Fenótipo , Retina/patologia , Retina/fisiopatologia , Retinosquise/patologia , Retinosquise/fisiopatologia
18.
PLoS One ; 11(2): e0148874, 2016.
Artigo em Inglês | MEDLINE | ID: mdl-26881841

RESUMO

Usher syndrome type III (USH3A) is an autosomal recessive disorder caused by mutations in clarin-1 (CLRN1) gene, leading to progressive retinal degeneration and sensorineural deafness. Efforts to develop therapies for preventing photoreceptor cell loss are hampered by the lack of a retinal phenotype in the existing USH3 mouse models and by conflicting reports regarding the endogenous retinal localization of clarin-1, a transmembrane protein of unknown function. In this study, we used an AAV-based approach to express CLRN1 in the mouse retina in order to determine the pattern of its subcellular localization in different cell types. We found that all major classes of retinal cells express AAV-delivered CLRN1 driven by the ubiquitous, constitutive small chicken ß-actin promoter, which has important implications for the design of future USH3 gene therapy studies. Within photoreceptor cells, AAV-expressed CLRN1 is mainly localized at the inner segment region and outer plexiform layer, similar to the endogenous expression of other usher proteins. Subretinal delivery using a full strength viral titer led to significant loss of retinal function as evidenced by ERG analysis, suggesting that there is a critical limit for CLRN1 expression in photoreceptor cells. Taken together, these results suggest that CLRN1 expression is potentially supported by a variety of retinal cells, and the right combination of AAV vector dose, promoter, and delivery method needs to be selected to develop safe therapies for USH3 disorder.


Assuntos
Terapia Genética , Proteínas de Membrana/biossíntese , Degeneração Retiniana/genética , Síndromes de Usher/genética , Animais , Dependovirus/genética , Modelos Animais de Doenças , Regulação da Expressão Gênica , Humanos , Proteínas de Membrana/genética , Camundongos , Retina/metabolismo , Retina/patologia , Degeneração Retiniana/patologia , Degeneração Retiniana/terapia , Síndromes de Usher/patologia , Síndromes de Usher/terapia
19.
Invest Ophthalmol Vis Sci ; 56(11): 6971-80, 2015 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-26513502

RESUMO

PURPOSE: The mutation S163R in complement C1q tumor necrosis factor-related protein-5 (C1QTNF5) causes an autosomal dominant disorder known as late-onset retinal degeneration (L-ORD). In this study, our goal is to evaluate the consequences of mutant S163R C1QTNF5 expression in mouse RPE following its delivery using an adeno-associated viral (AAV) vector. METHODS: We generated AAV vectors containing either human wild-type C1QTNF5 or mutant S163R C1QTNF5 driven by an RPE-specific BEST1 promoter, and delivered them subretinally into one eye of adult C57BL/6 mice. Transgene expression was detected by immunohistochemistry. Retinal function was assessed by full-field ERG. Pathological changes were further examined by digital fundus imaging and spectral-domain optical coherence tomography (SD-OCT). RESULTS: We show that the AAV-expressed mutant S163R leads to pathological effects similar to some of those found in patients with advanced L-ORD, including RPE thinning, RPE cell loss, and retinal degeneration. In addition, we provide in vivo evidence that mutant S163R C1QTNF5 can form large, transparent, spherical intracellular aggregates throughout the RPE, which are detectable by light microscopy. In contrast to AAV-expressed wild-type C1QTNF5, which is secreted apically from the RPE toward the photoreceptor cells and the outer limiting membrane, the S163R mutant is primarily routed toward the basal side of RPE, where it forms thick, extracellular deposits over time. CONCLUSIONS: Adeno-associated viral-targeted expression of mutant S163R in the RPE represents a useful approach for quickly generating animal models that mimic pathological features of L-ORD and offers the potential to understand disease mechanisms and develop therapeutic strategies.


Assuntos
Proteínas de Membrana/genética , Epitélio Pigmentado da Retina/patologia , Animais , Bestrofinas , Western Blotting , Proteínas do Olho/genética , Fundo de Olho , Expressão Gênica , Canais Iônicos/genética , Proteínas de Membrana/fisiologia , Camundongos , Camundongos Endogâmicos C57BL , Camundongos Transgênicos , Microscopia Eletrônica de Transmissão , Mutação de Sentido Incorreto , Degeneração Retiniana/genética , Epitélio Pigmentado da Retina/metabolismo , Epitélio Pigmentado da Retina/ultraestrutura , Tomografia de Coerência Óptica
20.
Hum Gene Ther ; 26(9): 593-602, 2015 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-26076799

RESUMO

Our collaborative successful gene replacement therapy using AAV vectors expressing a variant of human RPGR-ORF15 in two canine models provided therapeutic proof of concept for translation into human treatment. The ORF15 sequence contained within this AAV vector, however, has ORF15 DNA sequence variations compared to the published sequence that are likely due to its unusual composition of repetitive purine nucleotides. This mutability is a concern for AAV vector production and safety when contemplating a human trial. In this study, we establish the safety profile of AAV-hIRBP-hRPGR and AAV-hGRK1-hRPGR vectors used in the initial canine proof-of-principle experiments by demonstrating hRPGR-ORF15 sequence stability during all phases of manipulation, from plasmid propagation to vector production to its stability in vivo after subretinal administration to animals. We also evaluate potential toxicity in vivo by investigating protein expression, retinal structure and function, and vector biodistribution. Expression of hRPGR is detected in the inner segments and synaptic terminals of photoreceptors and is restricted to the connecting cilium when the vector is further diluted. Treated eyes exhibit no toxicity as assessed by retinal histopathology, immunocytochemistry, optical coherence tomography, fundoscopy, electroretinogram, and vector biodistribution. Therefore, the hRPGR-ORF15 variant in our AAV vectors appears to be a more stable form than the endogenous hRPGR cDNA when propagated in vitro. Its safety profile presented here in combination with its proven efficacy supports future gene therapy clinical trials.


Assuntos
Dependovirus/genética , Proteínas do Olho/genética , Terapia Genética , Sequência de Aminoácidos , Animais , Sequência de Bases , Vetores Genéticos , Humanos , Masculino , Camundongos Endogâmicos C57BL , Dados de Sequência Molecular , Fases de Leitura Aberta , Retina/patologia
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