RESUMEN
Autosomal dominant optic atrophy (DOA) is a progressive form of blindness caused by degeneration of retinal ganglion cells and their axons, mainly caused by mutations in the OPA1 mitochondrial dynamin like GTPase (OPA1) gene. OPA1 encodes a dynamin-like GTPase present in the mitochondrial inner membrane. When associated with OPA1 mutations, DOA can present not only ocular symptoms but also multi-organ symptoms (DOA plus). DOA plus often results from point mutations in the GTPase domain, which are assumed to have dominant-negative effects. However, the presence of mutations in the GTPase domain does not always result in DOA plus. Therefore, an experimental system to distinguish between DOA and DOA plus is needed. In this study, we found that loss-of-function mutations of the dOPA1 gene in Drosophila can imitate the pathology of optic nerve degeneration observed in DOA. We successfully rescued this degeneration by expressing the human OPA1 (hOPA1) gene, indicating that hOPA1 is functionally interchangeable with dOPA1 in the fly system. However, mutations previously identified did not ameliorate the dOPA1 deficiency phenotype. By expressing both WT and DOA plus mutant hOPA1 forms in the optic nerve of dOPA1 mutants, we observed that DOA plus mutations suppressed the rescue, facilitating the distinction between loss-of-function and dominant-negative mutations in hOPA1. This fly model aids in distinguishing DOA from DOA plus and guides initial hOPA1 mutation treatment strategies.
Asunto(s)
Modelos Animales de Enfermedad , Proteínas de Drosophila , GTP Fosfohidrolasas , Atrofia Óptica Autosómica Dominante , Animales , Atrofia Óptica Autosómica Dominante/genética , Atrofia Óptica Autosómica Dominante/metabolismo , Atrofia Óptica Autosómica Dominante/patología , GTP Fosfohidrolasas/genética , GTP Fosfohidrolasas/metabolismo , Proteínas de Drosophila/genética , Proteínas de Drosophila/metabolismo , Humanos , Drosophila melanogaster/genética , Drosophila melanogaster/metabolismo , Mutación , Drosophila/genética , Proteínas de la MembranaRESUMEN
Autosomal dominant optic atrophy (ADOA) is a rare progressive disease mainly caused by mutations in OPA1, a nuclear gene encoding for a mitochondrial protein that plays an essential role in mitochondrial dynamics, cell survival, oxidative phosphorylation, and mtDNA maintenance. ADOA is characterized by the degeneration of retinal ganglion cells (RGCs). This causes visual loss, which can lead to legal blindness in many cases. Nowadays, there is no effective treatment for ADOA. In this article, we have established an isogenic human RGC model for ADOA using iPSC technology and the genome editing tool CRISPR/Cas9 from a previously generated iPSC line of an ADOA plus patient harboring the pathogenic variant NM_015560.3: c.1861C>T (p.Gln621Ter) in heterozygosis in OPA1. To this end, a protocol based on supplementing the iPSC culture media with several small molecules and defined factors trying to mimic embryonic development has been employed. Subsequently, the created model was validated, confirming the presence of a defect of intergenomic communication, impaired mitochondrial respiration, and an increase in apoptosis and ROS generation. Finally, we propose the analysis of OPA1 expression by qPCR as an easy read-out method to carry out future drug screening studies using the created RGC model. In summary, this model provides a useful platform for further investigation of the underlying pathophysiological mechanisms of ADOA plus and for testing compounds with potential pharmacological action.
Asunto(s)
GTP Fosfohidrolasas , Células Madre Pluripotentes Inducidas , Atrofia Óptica Autosómica Dominante , Células Ganglionares de la Retina , Humanos , Atrofia Óptica Autosómica Dominante/genética , Atrofia Óptica Autosómica Dominante/patología , Atrofia Óptica Autosómica Dominante/metabolismo , Células Madre Pluripotentes Inducidas/metabolismo , GTP Fosfohidrolasas/genética , GTP Fosfohidrolasas/metabolismo , Células Ganglionares de la Retina/metabolismo , Células Ganglionares de la Retina/patología , Sistemas CRISPR-Cas , Edición Génica/métodos , Mutación , Apoptosis/genética , Especies Reactivas de Oxígeno/metabolismo , Mitocondrias/metabolismo , Mitocondrias/genéticaRESUMEN
Autosomal dominant optic atrophy plus (ADOA+) is characterized by primary optic nerve atrophy accompanied by a spectrum of degenerative neurological symptoms. Despite ongoing research, no effective treatments are currently available for this condition. Our study provided evidence for the pathogenicity of an unreported c.1780T>C variant in the OPA1 gene through patient-derived skin fibroblasts and an engineered HEK293T cell line with OPA1 downregulation. We demonstrate that OPA1 insufficiency promoted mitochondrial fragmentation and increased DRP1 expression, disrupting mitochondrial dynamics. Consequently, this disruption enhanced mitophagy and caused mitochondrial dysfunction, contributing to the ADOA+ phenotype. Notably, the Drp1 inhibitor, mitochondrial division inhibitor-1 (Mdivi-1), effectively mitigated the adverse effects of OPA1 impairment. These effects included reduced Drp1 phosphorylation, decreased mitochondrial fragmentation, and balanced mitophagy. Thus, we propose that intervening in DRP1 with Mdivi-1 could correct mitochondrial abnormalities, offering a promising therapeutic approach for managing ADOA+.
Asunto(s)
Dinaminas , Fibroblastos , GTP Fosfohidrolasas , Mitocondrias , Mitofagia , Atrofia Óptica Autosómica Dominante , Quinazolinonas , Humanos , Dinaminas/genética , Dinaminas/metabolismo , Dinaminas/antagonistas & inhibidores , Quinazolinonas/farmacología , Quinazolinonas/uso terapéutico , Atrofia Óptica Autosómica Dominante/genética , Atrofia Óptica Autosómica Dominante/patología , Atrofia Óptica Autosómica Dominante/tratamiento farmacológico , Atrofia Óptica Autosómica Dominante/metabolismo , Mitocondrias/metabolismo , Mitocondrias/efectos de los fármacos , Mitocondrias/patología , GTP Fosfohidrolasas/genética , GTP Fosfohidrolasas/metabolismo , Mitofagia/efectos de los fármacos , Células HEK293 , Fibroblastos/metabolismo , Fibroblastos/efectos de los fármacos , Dinámicas Mitocondriales/efectos de los fármacos , Masculino , FemeninoRESUMEN
Autosomal dominant optic atrophy (ADOA), mostly caused by heterozygous OPA1 mutations and characterized by retinal ganglion cell (RGC) loss and optic nerve degeneration, is one of the most common types of inherited optic neuropathies. Previous work using a two-dimensional (2D) differentiation model of induced pluripotent stem cells (iPSCs) has investigated ADOA pathogenesis but failed to agree on the effect of OPA1 mutations on RGC differentiation. Here, we use 3D retinal organoids capable of mimicking in vivo retinal development to resolve the issue. We generated isogenic iPSCs carrying the hotspot OPA1 c.2708_2711delTTAG mutation and found that the mutant variant caused defective initial and terminal differentiation and abnormal electrophysiological properties of organoid-derived RGCs. Moreover, this variant inhibits progenitor proliferation and results in mitochondrial dysfunction. These data demonstrate that retinal organoids coupled with gene editing serve as a powerful tool to definitively identify disease-related phenotypes and provide valuable resources to further investigate ADOA pathogenesis and screen for ADOA therapeutics.
Asunto(s)
Atrofia Óptica Autosómica Dominante , Células Ganglionares de la Retina , Humanos , Células Ganglionares de la Retina/metabolismo , Retina/metabolismo , Atrofia Óptica Autosómica Dominante/genética , Atrofia Óptica Autosómica Dominante/metabolismo , Atrofia Óptica Autosómica Dominante/patología , Mutación , Diferenciación Celular/genética , GTP Fosfohidrolasas/genética , GTP Fosfohidrolasas/metabolismoRESUMEN
Inner mitochondrial membrane fusion and cristae shape depend on optic atrophy protein 1, OPA1. Mutations in OPA1 lead to autosomal dominant optic atrophy (ADOA), an important cause of inherited blindness. The Guanosin Triphosphatase (GTPase) and GTPase effector domains (GEDs) of OPA1 are essential for mitochondrial fusion; yet, their specific roles remain elusive. Intriguingly, patients carrying OPA1 GTPase mutations have a higher risk of developing more severe multisystemic symptoms in addition to optic atrophy, suggesting pathogenic contributions for the GTPase and GED domains, respectively. We studied OPA1 GTPase and GED mutations to understand their domain-specific contribution to protein function by analyzing patient-derived cells and gain-of-function paradigms. Mitochondria from OPA1 GTPase (c.870+5G>A and c.889C>T) and GED (c.2713C>T and c.2818+5G>A) mutants display distinct aberrant cristae ultrastructure. While all OPA1 mutants inhibited mitochondrial fusion, some GTPase mutants resulted in elongated mitochondria, suggesting fission inhibition. We show that the GED is dispensable for fusion and OPA1 oligomer formation but necessary for GTPase activity. Finally, splicing defect mutants displayed a posttranslational haploinsufficiency-like phenotype but retained domain-specific dysfunctions. Thus, OPA1 domain-specific mutants result in distinct impairments in mitochondrial dynamics, providing insight into OPA1 function and its contribution to ADOA pathogenesis and severity.
Asunto(s)
Mitocondrias , Atrofia Óptica Autosómica Dominante , Humanos , Mitocondrias/metabolismo , Membranas Mitocondriales/metabolismo , GTP Fosfohidrolasas/genética , GTP Fosfohidrolasas/metabolismo , Atrofia Óptica Autosómica Dominante/genética , Atrofia Óptica Autosómica Dominante/metabolismo , Atrofia Óptica Autosómica Dominante/patología , MutaciónRESUMEN
Hereditary optic neuropathies are caused by the degeneration of retinal ganglion cells whose axons form the optic nerves, with a consistent genetic heterogeneity. As part of our diagnostic activity, we retrospectively evaluated the combination of Leber hereditary optic neuropathy mutations testing with the exon sequencing of 87 nuclear genes on 2186 patients referred for suspected hereditary optic neuropathies. The positive diagnosis rate in individuals referred for Leber hereditary optic neuropathy testing was 18% (199/1126 index cases), with 92% (184/199) carrying one of the three main pathogenic variants of mitochondrial DNA (m.11778G>A, 66.5%; m.3460G>A, 15% and m.14484T>C, 11%). The positive diagnosis rate in individuals referred for autosomal dominant or recessive optic neuropathies was 27% (451/1680 index cases), with 10 genes accounting together for 96% of this cohort. This represents an overall positive diagnostic rate of 30%. The identified top 10 nuclear genes included OPA1, WFS1, ACO2, SPG7, MFN2, AFG3L2, RTN4IP1, TMEM126A, NR2F1 and FDXR. Eleven additional genes, each accounting for less than 1% of cases, were identified in 17 individuals. Our results show that 10 major genes account for more than 96% of the cases diagnosed with our nuclear gene panel.
Asunto(s)
Atrofia Óptica Autosómica Dominante , Atrofia Óptica Hereditaria de Leber , Enfermedades del Nervio Óptico , Humanos , Atrofia Óptica Hereditaria de Leber/genética , Estudios Retrospectivos , Atrofia Óptica Autosómica Dominante/genética , Atrofia Óptica Autosómica Dominante/patología , Enfermedades del Nervio Óptico/genética , Mutación/genética , ADN Mitocondrial/genética , ATPasas Asociadas con Actividades Celulares Diversas/genética , Proteasas ATP-Dependientes/genética , Proteínas Portadoras/genética , Proteínas Mitocondriales/genética , Proteínas de la Membrana/genéticaRESUMEN
BACKGROUND: Single-stranded DNA-binding protein 1 (SSBP1) plays an essential role in mitochondrial DNA (mtDNA) replication and maintenance, as well as development of retina. Here, we describe the clinical findings and genetic basis of a family with two members affected with bilateral optic atrophy. MATERIALS AND METHODS: Clinical data were retrospectively collected from an electronic medical record system. Genetic results were obtained using exome sequencing (ES) and genome sequencing (GS). RESULTS: A 36-year-old man presented with low vision in both eyes since early childhood, with a best-corrected visual acuity of 20/500 in both eyes. He exhibited generalized optic atrophy and diffuse retinal nerve fiber layer thinning without retinal degeneration in both eyes. The family history was consistent with autosomal dominant traits. ES was performed; however, we did not identify any pathogenic variants in the known dominant optic atrophy genes. Subsequently, GS was performed, and it revealed a novel heterozygous c.364A>G p.(Lys122Glu) variant in SSBP1. In silico prediction supported it as deleterious, while segregation analysis detected it in his affected mother and his unaffected sister. No foveopathy or retinal degeneration was observed in the patient's family members. CONCLUSIONS: We report a novel pathogenic heterozygous SSBP1 variant in a family with autosomal dominant optic atrophy and incomplete penetrance. Furthermore, we demonstrated that GS is advantageous over ES even for the discovery of coding variants, providing uniform coverage. Therefore, GS should be emphasized to improve the molecular diagnostic rate of inherited optic neuropathy.
Asunto(s)
Atrofia Óptica Autosómica Dominante , Atrofia Óptica , Degeneración Retiniana , Preescolar , Masculino , Humanos , Adulto , Degeneración Retiniana/diagnóstico , Degeneración Retiniana/genética , Secuenciación del Exoma , Estudios Retrospectivos , Atrofia Óptica Autosómica Dominante/patología , Proteínas de Unión al ADN/genética , Atrofia Óptica/genética , ADN Mitocondrial/genética , Proteínas Mitocondriales/genéticaRESUMEN
Pathogenic variants of OPA1 have been associated with autosomal dominant optic atrophy (DOA), leading to optic, auditory, and other sensorineural neuropathies and myopathies. Using the Sendai virus delivery system, we generated induced pluripotent stem cells from the peripheral blood mononuclear cells of a female patient with the OPA1 pathogenic variant c.1468T>C (p.Cys490Arg). The resulting induced pluripotent stem cells exhibited a normal karyotype and pluripotency, as confirmed using immunofluorescence staining, and differentiated into three germ layers in vivo. This cellular model is a useful platform for investigating the pathogenic mechanisms of both blindness and deafness related to OPA1 variants.
Asunto(s)
Pérdida Auditiva , Células Madre Pluripotentes Inducidas , Atrofia Óptica Autosómica Dominante , Humanos , Femenino , Células Madre Pluripotentes Inducidas/patología , Leucocitos Mononucleares/patología , Mutación , Atrofia Óptica Autosómica Dominante/genética , Atrofia Óptica Autosómica Dominante/patología , Pérdida Auditiva/genética , GTP Fosfohidrolasas/genéticaRESUMEN
Dominant Optic Atrophy (DOA) is one of the most common inherited mitochondrial diseases, leading to blindness. It is caused by the chronic degeneration of the retinal ganglion cells (RGCs) and their axons forming the optic nerve. Until now, DOA has been mainly associated with genes encoding proteins involved in mitochondrial network dynamics. Using next-generation and exome sequencing, we identified for the first time heterozygous PMPCA variants having a causative role in the pathology of late-onset primary DOA in five patients. PMPCA encodes an α subunit of the mitochondrial peptidase (MPP), responsible for the cleavage and maturation of the mitochondrial precursor proteins imported from the cytoplasm into mitochondria. Recently, PMPCA has been identified as the gene responsible for Autosomal Recessive Cerebellar Ataxia type 2 (SCAR2) and another severe recessive mitochondrial disease. In this study, four PMPCA variants were identified, two are frameshifts (c.309delA and c.820delG) classified as pathogenic and two are missenses (c.1363G>A and c.1547G>A) classified with uncertain pathological significance. Functional assays on patients' fibroblasts show a hyperconnection of the mitochondrial network and revealed that frameshift variants reduced α-MPP levels, while not significantly affecting the respiratory machinery. These results suggest that alterations in mitochondrial peptidase function can affect the fusion-fission balance, a key element in maintaining the physiology of retinal ganglion cells, and consequently lead to their progressive degeneration.
Asunto(s)
Enfermedades Mitocondriales , Atrofia Óptica Autosómica Dominante , Humanos , Secuenciación de Nucleótidos de Alto Rendimiento , Proteínas Mitocondriales/genética , Atrofia Óptica Autosómica Dominante/genética , Atrofia Óptica Autosómica Dominante/metabolismo , Atrofia Óptica Autosómica Dominante/patología , Péptido Hidrolasas , Peptidasa de Procesamiento MitocondrialRESUMEN
PURPOSE: To describe the genetic and clinical features of nineteen patients from eleven unrelated Chinese pedigrees with OPA1-related autosomal dominant optic atrophy (ADOA) and define the phenotype-genotype correlations. METHODS: Detailed ophthalmic examinations were performed. Targeted next-generation sequencing (NGS) was conducted in the eleven probands using a custom designed panel PS400. Sanger sequencing and cosegregation were used to verify the identified variants. The pathogenicity of gene variants was evaluated according to American College of Medical Genetics and Genomics (ACMG) guidelines. RESULTS: Nineteen patients from the eleven unrelated Chinese ADOA pedigrees had impaired vision and optic disc pallor. Optical coherence tomography showed significant thinning of the retinal nerve fiber layer. The visual field showed varying degrees of central or paracentral scotoma. The onset of symptoms occurred between 3 and 24 years of age (median age 6 years). Eleven variants in OPA1 were identified in the cohort, and nine novel variants were identified. Among the novel variants, two splicing variants c.984 + 1_984 + 2delGT, c.1194 + 2 T > C, two stop-gain variants c.1937C > G, c.2830G > T, and one frameshift variant c.2787_2794del8, were determined to be pathogenic based on ACMG. A novel splicing variant c.1316-10 T > G was determined to be likely pathogenic. In addition, a novel missense c.1283A > C (p.N428T) and two novel splicing variants c.2496G > A and c.1065 + 5G > C were of uncertain significance. CONCLUSIONS: Six novel pathogenic variants were identified. The findings will facilitate genetic counselling by expanding the pathogenic mutation spectrum of OPA1.
Asunto(s)
Atrofia Óptica Autosómica Dominante , GTP Fosfohidrolasas/genética , Estudios de Asociación Genética , Humanos , Mutación , Atrofia Óptica Autosómica Dominante/genética , Atrofia Óptica Autosómica Dominante/patología , LinajeRESUMEN
Dominant optic atrophy (DOA), MIM # 605290, is the most common hereditary optic neuropathy inherited in an autosomal dominant pattern. Clinically, it presents a progressive decrease in vision, central visual field defects, and retinal ganglion cell loss. A biallelic mode of inheritance causes syndromic DOA or Behr phenotype, MIM # 605290. This case report details a family with Biallelic Optic Atrophy 1 (OPA1). The proband is a child with a severe phenotype and two variants in the OPA1 gene. He presented with congenital nystagmus, progressive vision loss, and optic atrophy, as well as progressive ataxia, and was found to have two likely pathogenic variants in his OPA1 gene: c.2287del (p.Ser763Valfs*15) maternally inherited and c.1311A>G (p.lIle437Met) paternally inherited. The first variant is predicted to be pathogenic and likely to cause DOA. In contrast, the second is considered asymptomatic by itself but has been reported in patients with DOA phenotype and is presumed to act as a phenotypic modifier. On follow-up, he developed profound vision impairment, intractable seizures, and metabolic strokes. A literature review of reported biallelic OPA1-related Behr syndrome was performed. Twenty-one cases have been previously reported. All share an early-onset, severe ocular phenotype and systemic features, which seem to be the hallmark of the disease.
Asunto(s)
Atrofia Óptica Autosómica Dominante , Atrofia Óptica , GTP Fosfohidrolasas/genética , Humanos , Masculino , Mutación , Atrofia Óptica/genética , Atrofia Óptica Autosómica Dominante/genética , Atrofia Óptica Autosómica Dominante/patología , LinajeRESUMEN
Autosomal dominant optic atrophy (DOA) is an inherited optic neuropathy that results in progressive, bilateral visual acuity loss and field defects. OPA1 is the causative gene in around 60% of cases of DOA. The majority of patients have a pure ocular phenotype, but 20% have extra-ocular features (DOA +). We report on a patient with DOA + manifesting as bilateral optic atrophy, spastic paraparesis, urinary incontinence and white matter changes in the central nervous system associated with a novel heterozygous splice variant NM_015560.2(OPA1):c.2356-1 G > T. Further characterisation, which was performed using fibroblasts obtained from a skin biopsy, demonstrated that this variant altered mRNA splicing of the OPA1 transcript, specifically a 21 base pair deletion at the start of exon 24, NM_015560.2(OPA1):p.Cys786_Lys792del. The majority of variant transcripts were shown to escape nonsense-mediated decay and modelling of the predicted protein structure suggests that the in-frame 7 amino acid deletion may affect OPA1 oligomerisation. Fibroblasts carrying the c.2356-1 G > T variant demonstrated impaired mitochondrial bioenergetics, membrane potential, increased cell death, and disrupted and fragmented mitochondrial networks in comparison to WT cells. This study suggests that the c.2356-1 G > T OPA1 splice site variant leads to a cryptic splice site activation and may manifest in a dominant-negative manner, which could account for the patient's severe syndromic phenotype.
Asunto(s)
Atrofia Óptica Autosómica Dominante , Sitios de Empalme de ARN , GTP Fosfohidrolasas/genética , Humanos , Mitocondrias/genética , Mitocondrias/patología , Mutación , Atrofia Óptica Autosómica Dominante/genética , Atrofia Óptica Autosómica Dominante/patologíaRESUMEN
PURPOSE: To describe the clinical phenotype of a cohort of patients with Wolfram syndrome (WS), focusing on the pattern of optic atrophy correlated with brain magnetic resonance imaging (MRI) measurements, as compared with patients with OPA1-related dominant optic atrophy (DOA). DESIGN: Retrospective, comparative cohort study. METHODS: We reviewed 25 patients with WS and 33 age-matched patients affected by OPA1-related DOA. Ophthalmologic, neurologic, endocrinologic, and MRI data from patients with WS were retrospectively retrieved. Ophthalmologic data were compared with data from patients with OPA1-related DOA and further analyzed for age dependency dividing patients in age quartiles. In a subgroup of patients with WS, we correlated the structural damage assessed by optical coherence tomography (OCT) with brain MRI morphologic measurements. Visual acuity (VA), visual field mean defect (MD), retinal nerve fiber layer (RNFL), and ganglion cell layer (GCL) thickness were assessed by OCT and MRI morphologic measurements of anterior and posterior visual pathways. RESULTS: Optic atrophy was present in 100% of patients with WS. VA, MD, and RNFL thickness loss were worse in patients with WS with a faster decline since early age as compared with patients with DOA, who displayed a more stable visual function over the years. Conversely, GCL sectors were overall thinner in patients with DOA since early age compared to patients with WS, in which GCL thickness started to decline later in life. The neuroradiologic subanalysis on 11 patients with WS exhibited bilateral thinning of the anterior optic pathway, especially the prechiasmatic optic nerves and optic tracts. Optic tract thinning was significantly correlated with GCL thickness but not with RNFL parameters. CONCLUSIONS: Our results showed a generally more severe and diffuse degeneration of both anterior and posterior visual pathways in patients with WS, with fast deterioration of visual function and structural OCT parameters since early age. The pattern observed with OCT suggests that retinal ganglion cell axonal degeneration (ie, RNFL) precedes cellular body atrophy (ie, GCL) by about a decade. This differs substantially from DOA, in which a more stable visual function is evident with predominant early loss of GCL, indirectly supporting the lack of a primary mitochondrial dysfunction in patients with WS.
Asunto(s)
Atrofia Óptica Autosómica Dominante , Enfermedades del Nervio Óptico , Síndrome de Wolfram , Estudios de Cohortes , Humanos , Mitocondrias/patología , Atrofia Óptica Autosómica Dominante/diagnóstico , Atrofia Óptica Autosómica Dominante/genética , Atrofia Óptica Autosómica Dominante/patología , Enfermedades del Nervio Óptico/patología , Células Ganglionares de la Retina/patología , Estudios Retrospectivos , Tomografía de Coherencia Óptica/métodos , Trastornos de la Visión , Síndrome de Wolfram/diagnósticoRESUMEN
OBJECTIVE: To investigate the effects of Bax inhibitor 1 (BI- 1) and optic atrophy protein 1 (OPA1) on vascular calcification (VC). METHODS: Mouse models of VC were established in ApoE-deficient (ApoE-/-) diabetic mice by high-fat diet feeding for 12 weeks followed by intraperitoneal injections with Nε-carboxymethyl-lysine for 16 weeks. ApoE-/- mice (control group), ApoE-/- diabetic mice (VC group), ApoE-/- diabetic mice with BI-1 overexpression (VC + BI-1TG group), and ApoE-/- diabetic mice with BI-1 overexpression and OPA1 knockout (VC+BI-1TG+OPA1-/- group) were obtained for examination of the degree of aortic calcification using von Kossa staining. The changes in calcium content in the aorta were analyzed using ELISA. The expressions of Runt-related transcription factor 2 (RUNX2) and bone morphogenetic protein 2 (BMP-2) were detected using immunohistochemistry, and the expression of cleaved caspase-3 was determined using Western blotting. Cultured mouse aortic smooth muscle cells were treated with 10 mmol/L ß-glycerophosphate for 14 days to induce calcification, and the changes in BI-1 and OPA1 protein expressions were examined using Western blotting and cell apoptosis was detected using TUNEL staining. RESULTS: ApoE-/- mice with VC showed significantly decreased expressions of BI-1 and OPA1 proteins in the aorta (P=0.0044) with obviously increased calcium deposition and expressions of RUNX2, BMP-2 and cleaved caspase-3 (P= 0.0041). Overexpression of BI-1 significantly promoted OPA1 protein expression and reduced calcium deposition and expressions of RUNX2, BMP-2 and cleaved caspase-3 (P=0.0006). OPA1 knockdown significantly increased calcium deposition and expressions of RUNX2, BMP-2 and cleaved caspase-3 in the aorta (P=0.0007). CONCLUSION: BI-1 inhibits VC possibly by promoting the expression of OPA1, reducing calcium deposition and inhibiting osteogenic differentiation and apoptosis of the vascular smooth muscle cells.
Asunto(s)
Diabetes Mellitus Experimental , GTP Fosfohidrolasas , Proteínas de la Membrana , Atrofia Óptica Autosómica Dominante , Calcificación Vascular , Animales , Apolipoproteínas E/metabolismo , Calcio/metabolismo , Caspasa 3/metabolismo , Células Cultivadas , Subunidad alfa 1 del Factor de Unión al Sitio Principal/metabolismo , Diabetes Mellitus Experimental/metabolismo , Diabetes Mellitus Experimental/patología , GTP Fosfohidrolasas/biosíntesis , GTP Fosfohidrolasas/genética , GTP Fosfohidrolasas/metabolismo , Proteínas de la Membrana/metabolismo , Ratones , Ratones Noqueados , Músculo Liso Vascular/metabolismo , Músculo Liso Vascular/patología , Miocitos del Músculo Liso/metabolismo , Miocitos del Músculo Liso/patología , Atrofia Óptica Autosómica Dominante/metabolismo , Atrofia Óptica Autosómica Dominante/patología , Osteogénesis , Calcificación Vascular/metabolismo , Calcificación Vascular/patología , Proteína X Asociada a bcl-2/metabolismoRESUMEN
Optic atrophy 1 (MIM #165500) is caused by pathogenic variants in the gene OPA1 (OPA1 MITOCHONDRIAL DYNAMIN-LIKE GTPase, MIM *605290) and is inherited in an autosomal dominant manner. We describe a 6-year-old male patient with severe early onset manifestation of optic atrophy, whose parents are subjectively asymptomatic. OPA1-sequence analysis revealed the heterozygous missense variant NM_015560.3:c.806C>T, p.(Ser269Phe) in the patient. Segregation analysis of the parents showed that the mother carried a low-grade postzygotic mosaic of this variant, which apparently also involves germline cells. In line with this, ophthalmological investigation of the mother showed subclinical manifestation of optic atrophy 1. This is the first report of an OPA1 postzygotic mosaic that was inherited to offspring.
Asunto(s)
Atrofia Óptica Autosómica Dominante , Atrofia Óptica , Niño , Dinaminas/genética , GTP Fosfohidrolasas/genética , Humanos , Masculino , Mutación Missense , Atrofia Óptica/patología , Atrofia Óptica Autosómica Dominante/genética , Atrofia Óptica Autosómica Dominante/patologíaRESUMEN
The purpose of this study was to evaluate the neuroprotective effects of omega-3 polyunsaturated fatty acid (ω3-PUFA) supplementation in a mouse model of OPA1-associated autosomal dominant optic atrophy (ADOA). The blood level of arachidonic acid (AA) and eicosapentaenoic acid (EPA) served to adjust the treatment dosage (AA/EPA = 1.0-1.5). Eight-month-old mice were allocated to four groups (n = 20/group): the ω3-PUFA-treated Opa1enu/+, untreated Opa1enu/+, ω3-PUFA-treated wild-type and untreated wild-type groups. Treated mice received the ω3-PUFAs, EPA and docosahexaenoic acid (DHA; 5:1 ratio) by daily gavage for 4 months based on the measured AA/EPA ratio. Blood, retina and optic nerve (ON) fatty acid levels were determined by gas chromatography, and the retina and ON were histologically examined. Western blotting and/or immunohistochemistry was performed to analyse retinal mediators involved in Opa1-mutation-mediated apoptosis, inflammation and oxidative stress. Increased EPA and reduced AA levels were primarily observed predominantly in the blood and retinal tissues, and a similarly high EPA level tended to be observed in the ONs of ω3-PUFA-treated mice. Retinal ganglion cell and ON axonal densities were higher in both mouse strains upon ω3-PUFA treatment than in the corresponding untreated groups. Caspase-3 expression analysis showed fewer apoptotic retinal cells in both groups of treated mice. Decreases in inflammatory microglia and astrocytes activation and proapoptotic Bcl-2-associated X protein (Bax) expression were noted in the treated groups, with no difference in the antioxidant superoxide dismutase-2 expression. ω3-PUFA supplementation had neuroprotective effects on the retinas of Opa1enu/+ and wild-type mice via blockade of microglia and astrocytes activation and suppression of Bax and caspase-3. Our findings indicated that inhibition of oxidative stress may not be involved in ω3-PUFA-mediated neuroprotection. These novel findings support the use of ω3-PUFAs as a beneficial therapy in the occurrence of ADOA, posing the basis for future clinical trials to confirm these observations.
Asunto(s)
Ácidos Grasos Omega-3 , Neuroglía , Fármacos Neuroprotectores , Atrofia Óptica Autosómica Dominante , Animales , Apoptosis , Ácido Araquidónico/metabolismo , Caspasa 3/metabolismo , Modelos Animales de Enfermedad , Ácidos Docosahexaenoicos/farmacología , Ácido Eicosapentaenoico/farmacología , Ácidos Grasos Omega-3/farmacología , GTP Fosfohidrolasas/metabolismo , Ratones , Neuroglía/metabolismo , Neuroglía/patología , Neuroprotección , Fármacos Neuroprotectores/farmacología , Atrofia Óptica Autosómica Dominante/tratamiento farmacológico , Atrofia Óptica Autosómica Dominante/genética , Atrofia Óptica Autosómica Dominante/metabolismo , Atrofia Óptica Autosómica Dominante/patología , Retina/metabolismo , Proteína X Asociada a bcl-2/metabolismoRESUMEN
Exonic (i.e. coding) variants in genes associated with disease can exert pathogenic effects both at the protein and mRNA level, either by altering the amino acid sequence or by affecting pre-mRNA splicing. The latter is often neglected due to the lack of RNA analyses in genetic diagnostic testing. In this study we considered both pathomechanisms and performed a comprehensive analysis of nine exonic nucleotide changes in OPA1, which is the major gene underlying autosomal dominant optic atrophy (DOA) and is characterized by pronounced allelic heterogeneity. We focused on the GTPase-encoding domain of OPA1, which harbors most of the missense variants associated with DOA. Given that the consensus splice sites extend into the exons, we chose a split codon, namely codon 438, for our analyses. Variants at this codon are the second most common cause of disease in our large cohort of DOA patients harboring disease-causing variants in OPA1. In silico splice predictions, heterologous splice assays, analysis of patient's RNA when available, and protein modeling revealed different molecular outcomes for variants at codon 438. The wildtype aspartate residue at amino acid position 438 is directly involved in the dimerization of OPA1 monomers. We found that six amino acid substitutions at codon 438 (i.e. all substitutions of the first and second nucleotide of the codon) destabilized dimerization while only substitutions of the first nucleotide of the codon caused exon skipping. Our study highlights the value of combining RNA analysis and protein modeling approaches to accurately assign patients to future precision therapies.
Asunto(s)
Atrofia Óptica Autosómica Dominante , Codón/genética , Análisis Mutacional de ADN , GTP Fosfohidrolasas/genética , Humanos , Mutación , Nucleótidos , Atrofia Óptica Autosómica Dominante/genética , Atrofia Óptica Autosómica Dominante/patología , LinajeRESUMEN
OBJECTIVE@#To investigate the effects of Bax inhibitor 1 (BI- 1) and optic atrophy protein 1 (OPA1) on vascular calcification (VC).@*METHODS@#Mouse models of VC were established in ApoE-deficient (ApoE-/-) diabetic mice by high-fat diet feeding for 12 weeks followed by intraperitoneal injections with Nε-carboxymethyl-lysine for 16 weeks. ApoE-/- mice (control group), ApoE-/- diabetic mice (VC group), ApoE-/- diabetic mice with BI-1 overexpression (VC + BI-1TG group), and ApoE-/- diabetic mice with BI-1 overexpression and OPA1 knockout (VC+BI-1TG+OPA1-/- group) were obtained for examination of the degree of aortic calcification using von Kossa staining. The changes in calcium content in the aorta were analyzed using ELISA. The expressions of Runt-related transcription factor 2 (RUNX2) and bone morphogenetic protein 2 (BMP-2) were detected using immunohistochemistry, and the expression of cleaved caspase-3 was determined using Western blotting. Cultured mouse aortic smooth muscle cells were treated with 10 mmol/L β-glycerophosphate for 14 days to induce calcification, and the changes in BI-1 and OPA1 protein expressions were examined using Western blotting and cell apoptosis was detected using TUNEL staining.@*RESULTS@#ApoE-/- mice with VC showed significantly decreased expressions of BI-1 and OPA1 proteins in the aorta (P=0.0044) with obviously increased calcium deposition and expressions of RUNX2, BMP-2 and cleaved caspase-3 (P= 0.0041). Overexpression of BI-1 significantly promoted OPA1 protein expression and reduced calcium deposition and expressions of RUNX2, BMP-2 and cleaved caspase-3 (P=0.0006). OPA1 knockdown significantly increased calcium deposition and expressions of RUNX2, BMP-2 and cleaved caspase-3 in the aorta (P=0.0007).@*CONCLUSION@#BI-1 inhibits VC possibly by promoting the expression of OPA1, reducing calcium deposition and inhibiting osteogenic differentiation and apoptosis of the vascular smooth muscle cells.
Asunto(s)
Animales , Ratones , Apolipoproteínas E/metabolismo , Calcio/metabolismo , Caspasa 3/metabolismo , Células Cultivadas , Subunidad alfa 1 del Factor de Unión al Sitio Principal/metabolismo , Diabetes Mellitus Experimental/patología , GTP Fosfohidrolasas/metabolismo , Proteínas de la Membrana/metabolismo , Ratones Noqueados , Músculo Liso Vascular/patología , Miocitos del Músculo Liso/patología , Atrofia Óptica Autosómica Dominante/patología , Osteogénesis , Calcificación Vascular/patología , Proteína X Asociada a bcl-2/metabolismoRESUMEN
Retinal ganglion cells (RGCs) undergo dendritic pruning in a variety of neurodegenerative diseases, including glaucoma and autosomal dominant optic atrophy (ADOA). Axotomising RGCs by severing the optic nerve generates an acute model of RGC dendropathy, which can be utilized to assess the therapeutic potential of treatments for RGC degeneration. Photobiomodulation (PBM) with red light provided neuroprotection to RGCs when administered ex vivo to wild-type retinal explants. In the current study, we used aged (13-15-month-old) wild-type and heterozygous B6;C3-Opa1Q285STOP (Opa1+/-) mice, a model of ADOA exhibiting RGC dendropathy. These mice were pre-treated with 4 J/cm2 of 670 nm light for five consecutive days before the eyes were enucleated and the retinas flat-mounted into explant cultures for 0-, 8- or 16-h ex vivo. RGCs were imaged by confocal microscopy, and their dendritic architecture was quantified by Sholl analysis. In vivo 670 nm light pretreatment inhibited the RGC dendropathy observed in untreated wild-type retinas over 16 h ex vivo and inhibited dendropathy in ON-center RGCs in wild-type but not Opa1+/- retinas. Immunohistochemistry revealed that aged Opa1+/- RGCs exhibited increased nitrosative damage alongside significantly lower activation of NF-κB and upregulation of DJ-1. PBM restored NF-κB activation in Opa1+/- RGCs and enhanced DJ-1 expression in both genotypes, indicating a potential molecular mechanism priming the retina to resist future oxidative insult. These data support the potential of PBM as a treatment for diseases involving RGC degeneration.
Asunto(s)
Atrofia Óptica Autosómica Dominante/terapia , Fototerapia , Proteína Desglicasa DJ-1/análisis , Células Ganglionares de la Retina/patología , Células Ganglionares de la Retina/efectos de la radiación , Animales , Modelos Animales de Enfermedad , Luz , Ratones , Neuroprotección/efectos de la radiación , Atrofia Óptica Autosómica Dominante/patología , Degeneración Retiniana , Células Ganglionares de la Retina/citología , Regulación hacia Arriba/efectos de la radiaciónRESUMEN
Autosomal dominant optic atrophy (ADOA) is an important cause of irreversible visual impairment in children and adolescents. About 60-90% of ADOA is caused by the pathogenic variants of OPA1 gene. By evaluating the pathogenicity of OPA1 variants and summarizing the relationship between the genotype and phenotype, this study aimed to provide a reference for clinical genetic test involving OPA1. Variants in OPA1 were selected from the exome sequencing results in 7092 cases of hereditary eye diseases and control groups from our in-house data. At the same time, the urine cells of some optic atrophy patients with OPA1 variants as well as their family members were collected and oxygen consumption rates (OCR) were measured in these cells to evaluate the pathogenicity of variants. As a result, 97 variants were detected, including 94 rare variants and 3 polymorphisms. And the 94 rare variants were classified into three groups: pathogenic (33), variants of uncertain significance (19), and likely benign (42). Our results indicated that the frameshift variants at the 3' terminus might be pathogenic, while the variants in exon 7 and intron 4 might be benign. The penetrance of the missense variants was higher than that of truncation variants. The OCR of cells with pathogenic OPA1 variants were significantly lower than those without pathogenic variants. In conclusion, some variants might be benign although predicted pathogenic in previous studies while some might have unknown pathogenesis. Measuring the OCR in urine cells could be used as a method to evaluate the pathogenicity of some OPA1 variants.