RESUMO
Glaucoma is a multifactorial neurodegenerative disease, characterized by degeneration of the retinal ganglion cells (RGCs). There has been little progress in developing efficient strategies for neuroprotection in glaucoma. We profiled the retina transcriptome of Lister Hooded rats at 2 weeks after optic nerve crush (ONC) and analyzed the data from the genomic fabric paradigm (GFP) to bring additional insights into the molecular mechanisms of the retinal remodeling after induction of RGC degeneration. GFP considers three independent characteristics for the expression of each gene: level, variability, and correlation with each other gene. Thus, the 17,657 quantified genes in our study generated a total of 155,911,310 values to analyze. This represents 8830x more data per condition than a traditional transcriptomic analysis. ONC led to a 57% reduction in RGC numbers as detected by retrograde labeling with 1,1'-dioctadecyl-3,3,3,3'-tetramethylindocarbocyanine perchlorate (DiI). We observed a higher relative expression variability after ONC. Gene expression stability was used as a measure of transcription control and disclosed a robust reduction in the number of very stably expressed genes. Predicted protein-protein interaction (PPI) analysis with STRING revealed axon and neuron projection as mostly decreased processes, consistent with RGC degeneration. Conversely, immune response PPIs were found among upregulated genes. Enrichment analysis showed that complement cascade and Notch signaling pathway, as well as oxidative stress and kit receptor pathway were affected after ONC. To expand our studies of altered molecular pathways, we examined the pairwise coordination of gene expressions within each pathway and within the entire transcriptome using Pearson correlations. ONC increased the number of synergistically coordinated pairs of genes and the number of similar profiles mainly in complement cascade and Notch signaling pathway. This deep bioinformatic study provided novel insights beyond the regulation of individual gene expression and disclosed changes in the control of expression of complement cascade and Notch signaling functional pathways that may be relevant for both RGC degeneration and remodeling of the retinal tissue after ONC.
Assuntos
Glaucoma , Traumatismos do Nervo Óptico , Nervo Óptico , Células Ganglionares da Retina , Transcriptoma , Animais , Feminino , Glaucoma/genética , Glaucoma/metabolismo , Glaucoma/patologia , Nervo Óptico/metabolismo , Nervo Óptico/patologia , Traumatismos do Nervo Óptico/genética , Traumatismos do Nervo Óptico/metabolismo , Traumatismos do Nervo Óptico/patologia , Ratos , Células Ganglionares da Retina/metabolismo , Células Ganglionares da Retina/patologiaRESUMO
Axonal damage is an early step in traumatic and neurodegenerative disorders of the central nervous system (CNS). Damaged axons are not able to regenerate sufficiently in the adult mammalian CNS, leading to permanent neurological deficits. Recently, we showed that inhibition of the autophagic protein ULK1 promotes neuroprotection in different models of neurodegeneration. Moreover, we demonstrated previously that axonal protection improves regeneration of lesioned axons. However, whether axonal protection mediated by ULK1 inhibition could also improve axonal regeneration is unknown. Here, we used an adeno-associated viral (AAV) vector to express a dominant-negative form of ULK1 (AAV.ULK1.DN) and investigated its effects on axonal regeneration in the CNS. We show that AAV.ULK1.DN fosters axonal regeneration and enhances neurite outgrowth in vitro. In addition, AAV.ULK1.DN increases neuronal survival and enhances axonal regeneration after optic nerve lesion, and promotes long-term axonal protection after spinal cord injury (SCI) in vivo. Interestingly, AAV.ULK1.DN also increases serotonergic and dopaminergic axon sprouting after SCI. Mechanistically, AAV.ULK1.DN leads to increased ERK1 activation and reduced expression of RhoA and ROCK2. Our findings outline ULK1 as a key regulator of axonal degeneration and regeneration, and define ULK1 as a promising target to promote neuroprotection and regeneration in the CNS.
Assuntos
Proteína Homóloga à Proteína-1 Relacionada à Autofagia/metabolismo , Axônios/metabolismo , Dependovirus/genética , Técnicas de Transferência de Genes , Vetores Genéticos , Regeneração Nervosa , Traumatismos do Nervo Óptico/terapia , Nervo Óptico/metabolismo , Traumatismos da Medula Espinal/terapia , Medula Espinal/metabolismo , Animais , Proteína Homóloga à Proteína-1 Relacionada à Autofagia/genética , Axônios/patologia , Células Cultivadas , Modelos Animais de Doenças , Neurônios Dopaminérgicos/metabolismo , Neurônios Dopaminérgicos/patologia , Regulação para Baixo , Feminino , Proteína Quinase 3 Ativada por Mitógeno/metabolismo , Crescimento Neuronal , Nervo Óptico/patologia , Traumatismos do Nervo Óptico/genética , Traumatismos do Nervo Óptico/metabolismo , Traumatismos do Nervo Óptico/patologia , Ratos Wistar , Neurônios Serotoninérgicos/metabolismo , Neurônios Serotoninérgicos/patologia , Medula Espinal/patologia , Traumatismos da Medula Espinal/genética , Traumatismos da Medula Espinal/metabolismo , Traumatismos da Medula Espinal/patologia , Fatores de Tempo , Proteínas rho de Ligação ao GTP/metabolismo , Quinases Associadas a rho/metabolismoRESUMO
Ocular and periocular traumatisms may result in loss of vision. Hypothermia provides a beneficial intervention for brain and heart conditions and, here, we study whether hypothermia can prevent retinal damage caused by traumatic neuropathy. Intraorbital optic nerve crush (IONC) or sham manipulation was applied to male rats. Some animals were subjected to hypothermia (8 °C) for 3 h following surgery. Thirty days later, animals were subjected to electroretinography and behavioral tests. IONC treatment resulted in amplitude reduction of the b-wave and oscillatory potentials of the electroretinogram, whereas the hypothermic treatment significantly (p < 0.05) reversed this process. Using a descending method of limits in a two-choice visual task apparatus, we demonstrated that hypothermia significantly (p < 0.001) preserved visual acuity. Furthermore, IONC-treated rats had a lower (p < 0.0001) number of retinal ganglion cells and a higher (p < 0.0001) number of TUNEL-positive cells than sham-operated controls. These numbers were significantly (p < 0.0001) corrected by hypothermic treatment. There was a significant (p < 0.001) increase of RNA-binding motif protein 3 (RBM3) and of BCL2 (p < 0.01) mRNA expression in the eyes exposed to hypothermia. In conclusion, hypothermia constitutes an efficacious treatment for traumatic vision-impairing conditions, and the cold-shock protein pathway may be involved in mediating the beneficial effects shown in the retina.
Assuntos
Hipotermia Induzida/métodos , Traumatismos do Nervo Óptico/terapia , Proteínas Proto-Oncogênicas c-bcl-2/genética , Proteínas de Ligação a RNA/genética , Doenças Retinianas/prevenção & controle , Animais , Modelos Animais de Doenças , Eletrorretinografia , Perfilação da Expressão Gênica , Masculino , Traumatismos do Nervo Óptico/complicações , Traumatismos do Nervo Óptico/genética , Traumatismos do Nervo Óptico/patologia , Ratos , Doenças Retinianas/etiologia , Doenças Retinianas/genética , Doenças Retinianas/patologia , Regulação para Cima , Acuidade VisualRESUMO
Elevated intraocular pressure is recognized as the principal risk factor for development of optic nerve head (ONH) injury. Lamina cribrosa (LC) cells and astrocytes are two types of cells in the ONH. We attempted to identify more target genes and predict their underlying molecular mechanisms. In this study, we performed meta-analysis of the data from two microarray sets containing samples from LC cells and astrocytes each. Our analysis indicated that 47 differentially expressed genes (DEGs) had been identified, and 24 of them were used to construct a bibliometric network with other related genes, including GSTT1 ENO2, CPE, PTN, PTGDS, IL6, MMP1, and EGFR. Further, our results predicted these genes might be involved in glaucoma development through Toll-like receptor signaling pathway, ErbB signaling pathway, and glioma and other cancer-related pathways. Therefore our study provides potential target genes and pathways for future therapeutic studies of glaucoma.
Assuntos
Astrócitos/metabolismo , Regulação da Expressão Gênica , Glaucoma/genética , Traumatismos do Nervo Óptico/genética , Astrócitos/patologia , Bibliometria , Redes Reguladoras de Genes , Glaucoma/patologia , Humanos , Disco Óptico/metabolismo , Disco Óptico/patologia , Traumatismos do Nervo Óptico/patologia , ProteômicaRESUMO
Spinal cord injury (SCI) releases a cascade of events that leads to the onset of an inhibitory milieu for axonal regeneration. Some of these changes result from the presence of repulsive factors that may restrict axonal outgrowth after trauma. The Eph receptor tyrosine kinase (RTK) family has emerged as a key repellent cue known to be involved in neurite outgrowth, synapse formation, and axonal pathfinding during development. Given the nonpermissive environment for axonal regeneration after SCI, we questioned whether re-expression of one of these molecules occurs during regenerative failure. We examined the expression profile of EphA3 at the mRNA and protein levels after SCI, using the NYU contusion model. There is a differential distribution of this molecule in the adult spinal cord and EphA3 showed an increase in expression after several injury models like optic nerve and brain injury. Standardized semi-quantitative RT-PCR analysis demonstrated a time-dependent change in EphA3 mRNA levels, without alterations in beta-actin levels. The basal level of EphA3 mRNA in the adult spinal cord is low and its expression was induced 2 days after trauma (the earliest time point analyzed) and this upregulation persisted for 28 days post-injury (the latest time point examined). These results were corroborated at the protein level by immunohistochemical analysis and the cell phenotype identified by double labeling studies. In control animals, EphA3 immunoreactivity was observed in motor neurons of the ventral horn but not in lesioned animals. In addition, GFAP-positive cells were visualized in the ventral region of injured white matter. These results suggest that upregulation of EphA3 in reactive astrocytes may contribute to the repulsive environment for neurite outgrowth and may be involved in the pathophysiology generated after SCI.