RESUMEN
Purpose: Mutations in the genes encoding type IV collagen alpha 1 (COL4A1) and alpha 2 (COL4A2) cause a multisystem disorder that includes ocular anterior segment dysgenesis (ASD) and glaucoma. We previously showed that transforming growth factor beta (TGFß) signaling was elevated in developing anterior segments from Col4a1 mutant mice and that reducing TGFß signaling ameliorated ASD, supporting a role for the TGFß pathway in disease pathogenesis. Here, we tested whether altered TGFß signaling also contributes to glaucoma-related phenotypes in Col4a1 mutant mice. Methods: To test the role of TGFß signaling in glaucoma-relevant phenotypes, we genetically reduced TGFß signaling using mice with mutated Tgfbr2, which encodes the common receptor for all TGFß ligands in Col4a1+/G1344D mice. We performed slit-lamp biomicroscopy and optical coherence tomography for qualitative and quantitative analyses of anterior and posterior ocular segments, histological analyses of ocular tissues and optic nerves, and intraocular pressure assessments using rebound tonometry. Results: Col4a1+/G1344D mice showed defects of the ocular drainage structures, including iridocorneal adhesions, and phenotypes consistent with glaucomatous neurodegeneration, including thinning of the nerve fiber layer, retinal ganglion cell loss, optic nerve head excavation, and optic nerve degeneration. We found that reducing TGFß receptor 2 (TGFBR2) was protective for ASD, ameliorated ocular drainage structure defects, and protected against glaucomatous neurodegeneration in Col4a1+/G1344D mice. Conclusions: Our results suggest that elevated TGFß signaling contributes to glaucomatous neurodegeneration in Col4a1 mutant mice.
Asunto(s)
Colágeno Tipo IV , Glaucoma , Receptor Tipo II de Factor de Crecimiento Transformador beta , Transducción de Señal , Factor de Crecimiento Transformador beta , Animales , Ratones , Segmento Anterior del Ojo/metabolismo , Segmento Anterior del Ojo/patología , Colágeno Tipo IV/metabolismo , Colágeno Tipo IV/genética , Modelos Animales de Enfermedad , Glaucoma/metabolismo , Glaucoma/genética , Glaucoma/patología , Presión Intraocular/fisiología , Ratones Endogámicos C57BL , Mutación , Nervio Óptico/patología , Nervio Óptico/metabolismo , Enfermedades del Nervio Óptico/metabolismo , Enfermedades del Nervio Óptico/genética , Fenotipo , Receptor Tipo II de Factor de Crecimiento Transformador beta/genética , Receptor Tipo II de Factor de Crecimiento Transformador beta/metabolismo , Células Ganglionares de la Retina/patología , Células Ganglionares de la Retina/metabolismo , Transducción de Señal/fisiología , Microscopía con Lámpara de Hendidura , Tomografía de Coherencia Óptica , Tonometría Ocular , Factor de Crecimiento Transformador beta/metabolismoRESUMEN
Programmed axon death is a druggable pathway of axon degeneration that has garnered considerable interest from pharmaceutical companies as a promising therapeutic target for various neurodegenerative disorders. In this review, we highlight mechanisms through which this pathway is activated in the retina and optic nerve, and discuss its potential significance for developing therapies for eye disorders and beyond. At the core of programmed axon death are two enzymes, NMNAT2 and SARM1, with pivotal roles in NAD metabolism. Extensive preclinical data in disease models consistently demonstrate remarkable, and in some instances, complete and enduring neuroprotection when this mechanism is targeted. Findings from animal studies are now being substantiated by genetic human data, propelling the field rapidly toward clinical translation. As we approach the clinical phase, the selection of suitable disorders for initial clinical trials targeting programmed axon death becomes crucial for their success. We delve into the multifaceted roles of programmed axon death and NAD metabolism in retinal and optic nerve disorders. We discuss the role of SARM1 beyond axon degeneration, including its potential involvement in neuronal soma death and photoreceptor degeneration. We also discuss genetic human data and environmental triggers of programmed axon death. Lastly, we touch upon potential therapeutic approaches targeting NMNATs and SARM1, as well as the nicotinamide trials for glaucoma. The extensive literature linking programmed axon death to eye disorders, along with the eye's suitability for drug delivery and visual assessments, makes retinal and optic nerve disorders strong contenders for early clinical trials targeting programmed axon death.
Asunto(s)
Proteínas del Dominio Armadillo , Axones , Nicotinamida-Nucleótido Adenililtransferasa , Enfermedades del Nervio Óptico , Humanos , Enfermedades del Nervio Óptico/tratamiento farmacológico , Enfermedades del Nervio Óptico/fisiopatología , Enfermedades del Nervio Óptico/metabolismo , Axones/fisiología , Nicotinamida-Nucleótido Adenililtransferasa/metabolismo , Animales , Proteínas del Dominio Armadillo/metabolismo , Proteínas del Citoesqueleto/metabolismo , Apoptosis/fisiología , Enfermedades de la Retina/tratamiento farmacológico , Enfermedades de la Retina/metabolismo , Enfermedades de la Retina/fisiopatología , NAD/metabolismoRESUMEN
Neuroprotection after injury or in neurodegenerative disease remains a major goal for basic and translational neuroscience. Retinal ganglion cells (RGCs), the projection neurons of the eye, degenerate in optic neuropathies after axon injury, and there are no clinical therapies to prevent their loss or restore their connectivity to targets in the brain. Here we demonstrate a profound neuroprotective effect of the exogenous expression of various Ca2+/calmodulin-dependent protein kinase II (CaMKII) isoforms in mice. A dramatic increase in RGC survival following the optic nerve trauma was elicited by the expression of constitutively active variants of multiple CaMKII isoforms in RGCs using adeno-associated viral (AAV) vectors across a 100-fold range of AAV dosing in vivo. Despite this neuroprotection, however, short-distance RGC axon sprouting was suppressed by CaMKII, and long-distance axon regeneration elicited by several pro-axon growth treatments was likewise inhibited even as CaMKII further enhanced RGC survival. Notably, in a dose-escalation study, AAV-expressed CaMKII was more potent for axon growth suppression than the promotion of survival. That diffuse overexpression of constitutively active CaMKII strongly promotes RGC survival after axon injury may be clinically valuable for neuroprotection per se. However, the associated strong suppression of the optic nerve axon regeneration demonstrates the need for understanding the intracellular domain- and target-specific CaMKII activities to the development of CaMKII signaling pathway-directed strategies for the treatment of optic neuropathies.
Asunto(s)
Enfermedades Neurodegenerativas , Enfermedades del Nervio Óptico , Traumatismos del Nervio Óptico , Ratones , Animales , Células Ganglionares de la Retina/metabolismo , Traumatismos del Nervio Óptico/metabolismo , Proteína Quinasa Tipo 2 Dependiente de Calcio Calmodulina/metabolismo , Axones/metabolismo , Enfermedades Neurodegenerativas/metabolismo , Regeneración Nerviosa/fisiología , Enfermedades del Nervio Óptico/metabolismo , Isoformas de Proteínas/metabolismo , Supervivencia Celular/fisiologíaRESUMEN
Retinal ganglion cells (RGCs) are essential for vision perception. In glaucoma and other optic neuropathies, RGCs and their optic axons undergo degenerative change and cell death; this can result in irreversible vision loss. Here we developed a rapid protocol for directly inducing RGC differentiation from human induced pluripotent stem cells (hiPSCs) by the overexpression of ATOH7, BRN3B, and SOX4. The hiPSC-derived RGC-like cells (iRGCs) show robust expression of various RGC-specific markers by whole transcriptome profiling. A functional assessment was also carried out and this demonstrated that these iRGCs display stimulus-induced neuronal activity, as well as spontaneous neuronal activity. Ethambutol (EMB), an effective first-line anti-tuberculosis agent, is known to cause serious visual impairment and irreversible vision loss due to the RGC degeneration in a significant number of treated patients. Using our iRGCs, EMB was found to induce significant dose-dependent and time-dependent increases in cell death and neurite degeneration. Western blot analysis revealed that the expression levels of p62 and LC3-II were upregulated, and further investigations revealed that EMB caused a blockade of lysosome-autophagosome fusion; this indicates that impairment of autophagic flux is one of the adverse effects of that EMB has on iRGCs. In addition, EMB was found to elevate intracellular reactive oxygen species (ROS) levels increasing apoptotic cell death. This could be partially rescued by the co-treatment with the ROS scavenger NAC. Taken together, our findings suggest that this iRGC model, which achieves both high yield and high purity, is suitable for investigating optic neuropathies, as well as being useful when searching for potential drugs for therapeutic treatment and/or disease prevention.
Asunto(s)
Células Madre Pluripotentes Inducidas , Enfermedades del Nervio Óptico , Humanos , Células Ganglionares de la Retina/metabolismo , Especies Reactivas de Oxígeno/metabolismo , Enfermedades del Nervio Óptico/metabolismo , Apoptosis , Etambutol/farmacología , Etambutol/metabolismo , Factores de Transcripción SOXC/metabolismoRESUMEN
Chronic neurodegeneration and acute injuries lead to neuron losses via diverse processes. We compared retinal ganglion cell (RGC) responses between chronic glaucomatous conditions and the acute injury model. Among major RGC subclasses, αRGCs and intrinsically photosensitive RGCs (ipRGCs) preferentially survive glaucomatous conditions, similar to findings in the retina subject to axotomy. Focusing on an αRGC intrinsic factor, Osteopontin (secreted phosphoprotein 1 [Spp1]), we found an ectopic neuronal expression of Osteopontin (Spp1) in other RGCs subject to glaucomatous conditions. This contrasted with the Spp1 downregulation subject to axotomy. αRGC-specific Spp1 elimination led to significant αRGC loss, diminishing their resiliency. Spp1 overexpression led to robust neuroprotection of susceptible RGC subclasses under glaucomatous conditions. In contrast, Spp1 overexpression did not significantly protect RGCs subject to axotomy. Additionally, SPP1 marked adult human RGC subsets with large somata and SPP1 expression in the aqueous humor correlated with glaucoma severity. Our study reveals Spp1's role in mediating neuronal resiliency in glaucoma.
Asunto(s)
Glaucoma , Enfermedades del Nervio Óptico , Humanos , Células Ganglionares de la Retina/metabolismo , Osteopontina , Nervio Óptico/metabolismo , Enfermedades del Nervio Óptico/metabolismoRESUMEN
Glaucomatous optic neuropathy (GON), a major cause of blindness, is characterized by the loss of retinal ganglion cells (RGCs) and the degeneration of their axons. Mitochondria are deeply involved in maintaining the health of RGCs and their axons. Therefore, lots of attempts have been made to develop diagnostic tools and therapies targeting mitochondria. Recently, we reported that mitochondria are uniformly distributed in the unmyelinated axons of RGCs, possibly owing to the ATP gradient. Thus, using transgenic mice expressing yellow fluorescent protein targeting mitochondria exclusively in RGCs within the retina, we assessed the alteration of mitochondrial distributions induced by optic nerve crush (ONC) via in vitro flat-mount retinal sections and in vivo fundus images captured with a confocal scanning ophthalmoscope. We observed that the mitochondrial distribution in the unmyelinated axons of survived RGCs after ONC remained uniform, although their density increased. Furthermore, via in vitro analysis, we discovered that the mitochondrial size is attenuated following ONC. These results suggest that ONC induces mitochondrial fission without disrupting the uniform mitochondrial distribution, possibly preventing axonal degeneration and apoptosis. The in vivo visualization system of axonal mitochondria in RGCs may be applicable in the detection of the progression of GON in animal studies and potentially in humans.
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Glaucoma , Enfermedades del Nervio Óptico , Traumatismos del Nervio Óptico , Ratones , Humanos , Animales , Células Ganglionares de la Retina/metabolismo , Traumatismos del Nervio Óptico/metabolismo , Dinámicas Mitocondriales , Glaucoma/metabolismo , Enfermedades del Nervio Óptico/metabolismo , Axones/metabolismo , Ratones Transgénicos , Modelos Animales de Enfermedad , Mitocondrias/metabolismoRESUMEN
Optic neuropathies refer to a group of ocular disorders with abnormalities or dysfunction of the optic nerve, sharing a common pathophysiology of retinal ganglion cell (RGC) death and axonal loss. RGCs, as the retinal neurons in the central nervous system, show limited capacity in regeneration or recovery upon diseases or after injuries. Critically, there is still no effective clinical treatment to cure most types of optic neuropathies. Recently, stem cell therapy was proposed as a potential treatment strategy for optic neuropathies. Adult stem cells, including mesenchymal stem cells and hematopoietic stem cells, have been applied in clinical trials based on their neuroprotective properties. In this article, the applications of adult stem cells on different types of optic neuropathies and the related mechanisms will be reviewed. Research updates on the strategies to enhance the neuroprotective effects of human adult stem cells will be summarized. This review article aims to enlighten the research scientists on the diversified functions of adult stem cells and consideration of adult stem cells as a potential treatment for optic neuropathies in future clinical practices.
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Células Madre Adultas , Fármacos Neuroprotectores , Enfermedades del Nervio Óptico , Traumatismos del Nervio Óptico , Humanos , Fármacos Neuroprotectores/uso terapéutico , Nervio Óptico , Enfermedades del Nervio Óptico/tratamiento farmacológico , Enfermedades del Nervio Óptico/metabolismo , Traumatismos del Nervio Óptico/tratamiento farmacológico , Células Ganglionares de la RetinaRESUMEN
Glutamate excitotoxicity may contribute to retinal ganglion cell (RGC) degeneration in glaucoma and other optic neuropathies, leading to irreversible blindness. Growing evidence has linked impaired mitochondrial quality control with RGCs degeneration, while parkin, an E3 ubiquitin ligase, has proved to be protective and promotes mitophagy in RGCs against excitotoxicity. The purpose of this study was to explore whether a small molecule S3 could modulate parkin-mediated mitophagy and has therapeutic potential for RGCs. The results showed that as an inhibitor of deubiquitinase USP30, S3 protected cultured RGCs and improved mitochondrial health against NMDA-induced excitotoxicity. Administration of S3 promoted the parkin expression and its downstream mitophagy-related proteins in RGCs. An upregulated ubiquitination level of Mfn2 and protein level of OPA1 were also observed in S3-treated RGCs, while parkin knockdown resulted in a major loss of the protective effect of S3 on RGCs under excitotoxicity. These findings demonstrated that S3 promoted RGC survival mainly through enhancing parkin-mediated mitophagy against excitotoxicity. The neuroprotective value of S3 in glaucoma and other optic neuropathies deserves further investigation.
Asunto(s)
Mitofagia , Fármacos Neuroprotectores , Células Ganglionares de la Retina , Ubiquitina-Proteína Ligasas , Glaucoma/tratamiento farmacológico , Glaucoma/metabolismo , Ácido Glutámico/metabolismo , Humanos , Proteínas Mitocondriales/antagonistas & inhibidores , Proteínas Mitocondriales/metabolismo , Mitofagia/efectos de los fármacos , Mitofagia/fisiología , Fármacos Neuroprotectores/farmacología , Fármacos Neuroprotectores/uso terapéutico , Neurotoxinas/metabolismo , Enfermedades del Nervio Óptico/tratamiento farmacológico , Enfermedades del Nervio Óptico/metabolismo , Células Ganglionares de la Retina/efectos de los fármacos , Células Ganglionares de la Retina/metabolismo , Tioléster Hidrolasas/antagonistas & inhibidores , Tioléster Hidrolasas/metabolismo , Ubiquitina-Proteína Ligasas/metabolismoRESUMEN
Glaucomatous optic neuropathy is the leading cause of irreversible blindness in the world. The chronic disease is characterized by optic nerve degeneration and vision field loss. The reduction of intraocular pressure remains the only proven glaucoma treatment, but it does not prevent further neurodegeneration. There are three major classes of cells in the human optic nerve head (ONH): lamina cribrosa (LC) cells, glial cells, and scleral fibroblasts. These cells provide support for the LC which is essential to maintain healthy retinal ganglion cell (RGC) axons. All these cells demonstrate responses to glaucomatous conditions through extracellular matrix remodeling. Therefore, investigations into alternative therapies that alter the characteristic remodeling response of the ONH to enhance the survival of RGC axons are prevalent. Understanding major remodeling pathways in the ONH may be key to developing targeted therapies that reduce deleterious remodeling.
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Glaucoma , Disco Óptico , Enfermedades del Nervio Óptico , Glaucoma/metabolismo , Glaucoma/terapia , Humanos , Presión Intraocular , Disco Óptico/metabolismo , Enfermedades del Nervio Óptico/metabolismo , Células Ganglionares de la RetinaRESUMEN
As in glaucoma and other optic neuropathies cellular dysfunction often precedes cell death, the assessment of retinal ganglion cell (RGC) function represents a key outcome measure for neuroprotective strategies aimed at targeting distressed but still viable cells. RGC dysfunction can be assessed with the pattern electroretinogram (PERG), a sensitive measure of electrical activity of RGCs that is recorded non-invasively in human subjects and mouse models. Here, we offer a conceptual framework based on an intuitive state-transition model used for disease management in patients to identify progressive, potentially reversible stages of RGC dysfunction leading to cell death in mouse models of glaucoma and other optic neuropathies. We provide mathematical equations to describe state-transitions with a set of modifiable parameters that alter the time course and severity of state-transitions, which can be used for hypothesis testing and fitting experimental PERG data. PERG dynamics as a function of physiological stimuli are also used to differentiate phenotypic and altered RGC response dynamics, to assess susceptibility to stressors and to assess reversible dysfunction upon pharmacological treatment.
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Modelos Neurológicos , Enfermedades del Nervio Óptico/metabolismo , Enfermedades del Nervio Óptico/fisiopatología , Células Ganglionares de la Retina/metabolismo , Animales , Modelos Animales de Enfermedad , Electrorretinografía , Humanos , Ratones , Enfermedades del Nervio Óptico/patología , Células Ganglionares de la Retina/patologíaRESUMEN
Astrocytes are intimately involved in the response to neurodegenerative stress and have become an attractive target for the development of neuroprotective therapies. However, studies often focus on astrocytes as single-cell units. Astrocytes are densely interconnected by gap junctions that are composed primarily of the protein connexin-43 (Cx43) and can function as a broader network of cells. Such networks contribute to a number of important processes, including metabolite distribution and extracellular ionic buffering, and are likely to play an important role in the progression of neurodegenerative disease. This review will focus on the pro-degenerative and pro-survival influence of astrocyte Cx43 in disease progression, with a focus on the roles of gap junctions and hemichannels in the spread of degenerative stress. Finally, we will highlight the specific evidence for targeting these networks in the treatment of glaucomatous neurodegeneration and other optic neuropathies.
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Astrocitos/metabolismo , Conexina 43/metabolismo , Uniones Comunicantes/metabolismo , Glaucoma/metabolismo , Enfermedades Neurodegenerativas/metabolismo , Enfermedades del Nervio Óptico/metabolismo , Astrocitos/patología , Uniones Comunicantes/patología , Glaucoma/patología , Humanos , Enfermedades Neurodegenerativas/patología , Enfermedades del Nervio Óptico/patologíaRESUMEN
AIMS: A previous study reported that intravitreal injection of αA-crystallin inhibits glial scar formation after optic nerve traumatic injury. The purpose of this study was to investigate the effect of αA-crystallin on optic nerve astrocytes induced by oxygen glucose deprivation (OGD) in vitro. MATERIALS AND METHODS: Optic nerve astrocytes from newborn Long Evans rats were cultured with αA-crystallin (10-4 g/l) to detect the effects of αA-crystallin on astrocytes. Using a scratch assay, the effect of αA-crystallin treatment on astrocyte migration was assessed. Astrocytes were exposed to OGD and glucose reintroduction/reoxygenation culture for 24 h and 48 h. The expression of glial fibrillary acidic protein (GFAP) and neurocan were subsequently evaluated via immunocytochemistry and western blot. BMP2/4, BMPRIa/Ib and Smad1/5/8 mRNA expression levels were detected by RT-PCR. KEY FINDINGS: The results showed that αA-crystallin slowed the migration of astrocytes in filling the scratch gaps. GFAP and neurocan expression in astrocytes was increased after OGD. However, after treatment with αA-crystallin, GFAP and neurocan expression levels clearly decreased. Furthermore, RT-PCR showed that BMP2 and BMP4 mRNA expression levels decreased significantly. SIGNIFICANCE: These results suggest that αA-crystallin inhibits the activation of astrocytes after OGD injury in vitro. Inhibition of the BMP/Smad signaling pathway might be the mechanism underlying this effect.
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Astrocitos/metabolismo , Proteína Ácida Fibrilar de la Glía/metabolismo , Glucosa/metabolismo , Nervio Óptico/metabolismo , Oxígeno/metabolismo , Cadena A de alfa-Cristalina/administración & dosificación , Animales , Proteína Morfogenética Ósea 2/metabolismo , Proteína Morfogenética Ósea 4/metabolismo , Proteoglicanos Tipo Condroitín Sulfato/metabolismo , Humanos , Técnicas In Vitro , Neurocano , Enfermedades del Nervio Óptico/metabolismo , Ratas , Ratas Long-Evans , Transducción de Señal , Proteínas Smad/metabolismoRESUMEN
PURPOSE OF REVIEW: This review explores metabolic syndrome (MetS) as a risk factor that accelerates aging in retinal neurons and may contribute to the neurodegeneration seen in glaucomatous optic neuropathy (GON) and age-related macular degeneration (AMD). RECENT FINDINGS: Both animal model experiments and epidemiologic studies suggest that metabolic stress may lead to aberrant regulation of a number of cellular pathways that ultimately lead to premature aging of the cell, including those of a neuronal lineage. SUMMARY: GON and AMD are each leading causes of irreversible blindness worldwide. Aging is a significant risk factor in the specific retinal neuron loss that is seen with each condition. Though aging at a cellular level is difficult to define, there are many mechanistic modifiers of aging. Metabolic-related stresses induce inflammation, oxidative stress, mitochondrial dysfunction, endoplasmic reticulum stress, alterations to the unfolded protein response, defects in autophagy, alterations to the microbiome, and deposition of advanced glycation end products that can all hasten the aging process. Due to the number of variables related to metabolic health, defining criteria to enable the study of risk factors at a population level is challenging. MetS is a definable constellation of related metabolic risk factors that includes enlarged waist circumference, dyslipidemia, systemic hypertension, and hyperglycemia. MetS has been associated with both GON and AMD and may contribute to disease onset and/or progression in each disease.
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Senescencia Celular/fisiología , Síndrome Metabólico/metabolismo , Retina/metabolismo , Animales , Glaucoma/metabolismo , Humanos , Degeneración Macular/metabolismo , Enfermedades del Nervio Óptico/metabolismo , Estrés OxidativoRESUMEN
Inherited optic neuropathies are the most common mitochondrial diseases, leading to neurodegeneration involving the irreversible loss of retinal ganglion cells, optic nerve degeneration and central visual loss. Importantly, properly regulated mitochondrial dynamics are critical for maintaining cellular homeostasis, and are further regulated by MIEF1 (mitochondrial elongation factor 1) which encodes for MID51 (mitochondrial dynamics protein 51), an outer mitochondrial membrane protein that acts as an adaptor protein to regulate mitochondrial fission. However, dominant mutations in MIEF1 have not been previously linked to any human disease. Using targeted sequencing of genes involved in mitochondrial dynamics, we report the first heterozygous variants in MIEF1 linked to disease, which cause an unusual form of late-onset progressive optic neuropathy characterized by the initial loss of peripheral visual fields. Pathogenic MIEF1 variants linked to optic neuropathy do not disrupt MID51's localization to the outer mitochondrial membrane or its oligomerization, but rather, significantly disrupt mitochondrial network dynamics compared to wild-type MID51 in high spatial and temporal resolution confocal microscopy live imaging studies. Together, our study identifies dominant MIEF1 mutations as a cause for optic neuropathy and further highlights the important role of properly regulated mitochondrial dynamics in neurodegeneration.
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Mitocondrias/metabolismo , Proteínas Mitocondriales/metabolismo , Enfermedades del Nervio Óptico/genética , Factores de Elongación de Péptidos/genética , Humanos , Proteínas de la Membrana/genética , Dinámicas Mitocondriales/genética , Dinámicas Mitocondriales/fisiología , Proteínas Mitocondriales/genética , Enfermedades del Nervio Óptico/metabolismo , Factores de Elongación de Péptidos/metabolismo , Células Ganglionares de la Retina/metabolismoRESUMEN
Inherited optic neuropathies share visual impairment due to the degeneration of retinal ganglion cells (RGCs) as the hallmark of the disease. This group of genetic disorders are caused by mutations in nuclear genes or in the mitochondrial DNA (mtDNA). An impaired mitochondrial function is the underlying mechanism of these diseases. Currently, optic neuropathies lack an effective treatment, and the implementation of induced pluripotent stem cell (iPSC) technology would entail a huge step forward. The generation of iPSC-derived RGCs would allow faithfully modeling these disorders, and these RGCs would represent an appealing platform for drug screening as well, paving the way for a proper therapy. Here, we review the ongoing two-dimensional (2D) and three-dimensional (3D) approaches based on iPSCs and their applications, taking into account the more innovative technologies, which include tissue engineering or microfluidics.
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Diferenciación Celular , ADN Mitocondrial , Enfermedades Genéticas Congénitas , Células Madre Pluripotentes Inducidas , Mitocondrias , Enfermedades del Nervio Óptico , ADN Mitocondrial/genética , ADN Mitocondrial/metabolismo , Enfermedades Genéticas Congénitas/genética , Enfermedades Genéticas Congénitas/metabolismo , Enfermedades Genéticas Congénitas/patología , Humanos , Células Madre Pluripotentes Inducidas/metabolismo , Células Madre Pluripotentes Inducidas/patología , Mitocondrias/genética , Mitocondrias/metabolismo , Enfermedades del Nervio Óptico/genética , Enfermedades del Nervio Óptico/metabolismo , Enfermedades del Nervio Óptico/patologíaRESUMEN
Glaucoma and other optic neuropathies are characterized by progressive dysfunction and loss of retinal ganglion cells and their axons. Given the high prevalence of glaucoma-related blindness and the availability of treatment options, improving the diagnosis and precise monitoring of progression in these conditions is paramount. Here we review recent progress in the development of novel biomarkers for glaucoma in the context of disease pathophysiology and we propose future steps for the field, including integration of exploratory biomarker outcomes into prospective therapeutic trials. We anticipate that, when validated, some of the novel glaucoma biomarkers discussed here will prove useful for clinical diagnosis and prediction of progression, as well as monitoring of clinical responses to standard and investigational therapies.
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Biomarcadores/metabolismo , Glaucoma/metabolismo , Enfermedades del Nervio Óptico/metabolismo , Animales , Axones/patología , Modelos Animales de Enfermedad , Glaucoma/fisiopatología , Humanos , Enfermedades del Nervio Óptico/fisiopatología , Células Ganglionares de la Retina/patologíaRESUMEN
Purpose: The lamina cribrosa (LC) is a key site of damage in glaucomatous optic neuropathy. We previously found that glaucoma LC cells have an increased profibrotic gene expression, with mitochondrial dysfunction in the form of decreased mitochondrial membrane potential. Altered cell bioenergetics have recently been reported in organ fibrosis and in cancer. In this study, we carried out a systematic mitochondrial bioenergetic assessment and measured markers of alternative sources of cellular energy in normal and glaucoma LC cells. Methods: LC cells from three glaucoma donors and three age-matched normal controls were assessed using VICTOR X4 Perkin Elmer (Waltham, MA) plate reader with different phosphorescent and luminescent probes. adenosine triphosphate levels, oxygen consumption rate, and extracellular acidification were measured and normalized to total protein content. RNA and protein expression levels of MCT1, MCT4, MTFHD2, and GLS2 were quantified using real-time RT-PCR and Western blotting. Results: Glaucoma LC cells contain significantly less adenosine triphosphate (P < .05) when supplied with either glucose or galactose. They also showed significantly diminished oxygen consumption in both basal and maximal respiration with more lactic acid contribution in ECA. Both mRNA and protein expression levels of MCT1, MCT4, MTHFD2, and GLS2 were significantly increased in glaucoma LC cells. Conclusions: We demonstrate evidence of metabolic reprogramming (The Warburg effect) in glaucoma LC cells. Expression of markers of glycolysis, glutamine, and one carbon metabolism are elevated in glaucoma cells at both the mRNA and protein levels. A better understanding of bioenergetics in glaucoma may help in the development of new therapeutics.
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Glaucoma de Ángulo Abierto/metabolismo , Glucólisis/fisiología , Enfermedades Mitocondriales/metabolismo , Disco Óptico/metabolismo , Enfermedades del Nervio Óptico/metabolismo , Fosforilación Oxidativa , Adenosina Trifosfato/metabolismo , Aminohidrolasas/genética , Aminohidrolasas/metabolismo , Biomarcadores , Western Blotting , Células Cultivadas , Perfilación de la Expresión Génica , Glaucoma de Ángulo Abierto/patología , Proteína Ácida Fibrilar de la Glía/metabolismo , Glutaminasa/genética , Glutaminasa/metabolismo , Humanos , Metilenotetrahidrofolato Deshidrogenasa (NADP)/genética , Metilenotetrahidrofolato Deshidrogenasa (NADP)/metabolismo , Enfermedades Mitocondriales/patología , Transportadores de Ácidos Monocarboxílicos/genética , Transportadores de Ácidos Monocarboxílicos/metabolismo , Enzimas Multifuncionales/genética , Enzimas Multifuncionales/metabolismo , Proteínas Musculares/genética , Proteínas Musculares/metabolismo , Disco Óptico/patología , Enfermedades del Nervio Óptico/patología , Consumo de Oxígeno/fisiología , ARN Mensajero/genética , Reacción en Cadena en Tiempo Real de la Polimerasa , Simportadores/genética , Simportadores/metabolismo , Donantes de TejidosRESUMEN
The main goal of this thematic issue was to bring both original research papers and reviews together to provide an insight into the rather broad topic of molecular biology of retinal ganglion cells (RGCs) [...].
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Biología Molecular , Enfermedades del Nervio Óptico/metabolismo , Células Ganglionares de la Retina/metabolismo , Humanos , InvestigaciónRESUMEN
Radiation-induced optic neuropathy (RION) is a devastating complication following external beam radiation therapy (EBRT) that leads to acute vision loss. To date, no efficient, available treatment for this complication, due partly to the lack of understanding regarding the developmental processes behind RION. Here, we report radiation caused changes in mitochondrial dynamics by regulating the mitochondrial fission proteins dynamin-related protein 1 (Drp1) and fission-1 (Fis1). Concurrent with an excessive production of reactive oxygen species (ROS), both neuronal injury and visual dysfunction resulted. Further, our findings delineate an important mechanism by which cyclin-dependent kinase 5 (Cdk5)-mediated phosphorylation of Drp1 (Ser616) regulates defects in mitochondrial dynamics associated with neuronal injury in the development of RION. Both the pharmacological inhibition of Cdk5 by roscovitine and the inhibition of Drp1 by mdivi-1 inhibited mitochondrial fission and the production of ROS associated with radiation-induced neuronal loss. Taken together, these findings may have clinical significance in preventing the development of RION.
Asunto(s)
Quinasa 5 Dependiente de la Ciclina/metabolismo , Dinaminas/metabolismo , Mitocondrias/efectos de la radiación , Enfermedades del Nervio Óptico/etiología , Animales , Apoptosis/efectos de la radiación , Quinasa 5 Dependiente de la Ciclina/antagonistas & inhibidores , Dinaminas/antagonistas & inhibidores , Humanos , Masculino , Ratones , Ratones Endogámicos BALB C , Mitocondrias/metabolismo , Dinámicas Mitocondriales/efectos de la radiación , Neuronas/metabolismo , Neuronas/patología , Neuronas/efectos de la radiación , Enfermedades del Nervio Óptico/sangre , Enfermedades del Nervio Óptico/metabolismo , Enfermedades del Nervio Óptico/patología , Fosforilación , Quinazolinonas/farmacología , Traumatismos Experimentales por Radiación/metabolismo , Radioterapia/efectos adversos , Ratas , Roscovitina/farmacologíaRESUMEN
In this work, we develop a robust, extensible tool to automatically and accurately count retinal ganglion cell axons in optic nerve (ON) tissue images from various animal models of glaucoma. We adapted deep learning to regress pixelwise axon count density estimates, which were then integrated over the image area to determine axon counts. The tool, termed AxoNet, was trained and evaluated using a dataset containing images of ON regions randomly selected from whole cross sections of both control and damaged rat ONs and manually annotated for axon count and location. This rat-trained network was then applied to a separate dataset of non-human primate (NHP) ON images. AxoNet was compared to two existing automated axon counting tools, AxonMaster and AxonJ, using both datasets. AxoNet outperformed the existing tools on both the rat and NHP ON datasets as judged by mean absolute error, R2 values when regressing automated vs. manual counts, and Bland-Altman analysis. AxoNet does not rely on hand-crafted image features for axon recognition and is robust to variations in the extent of ON tissue damage, image quality, and species of mammal. Therefore, AxoNet is not species-specific and can be extended to quantify additional ON characteristics in glaucoma and potentially other neurodegenerative diseases.