In JoVE (1)
Other Publications (8)
- Brain Research. Developmental Brain Research
- The Journal of Neuroscience : the Official Journal of the Society for Neuroscience
- Investigative Ophthalmology & Visual Science
- The Journal of Biological Chemistry
- Investigative Ophthalmology & Visual Science
- The Journal of Comparative Neurology
- PloS One
- Disease Models & Mechanisms
Articles by Alejandra Bosco in JoVE
En Vivo Dynamique de la rétine microglial activation cours neurodégénérescence: confocale ophtalmoscopique Imaging and Cell Morphometry dans Souris glaucome Alejandra Bosco1, Cesar O. Romero1, Balamurali K. Ambati2, Monica L. Vetter1 1Department of Neurobiology & Anatomy, University of Utah, 2Department of Ophthalmology & Visual Sciences, University of Utah activation de cellules microgliales et microgliose sont des réponses clés à la neurodégénérescence chronique. Ici, nous présentons les méthodes pour in vivo, la visualisation à long terme de la rétine CX3CR1-GFP + cellules microgliales par ophtalmoscopie confocale, et pour le seuil et analyses morphométriques d'identifier et de quantifier leur activation. Nous surveillons changements microgliales durant les premiers stades de glaucome liée à l'âge.
Other articles by Alejandra Bosco on PubMed
Cell Death in the Inner Nuclear Layer of the Retina is Modulated by BDNF Brain Research. Developmental Brain Research. Dec, 2002 | Pubmed ID: 12480149 Developing amacrine cells in the vertebrate retina undergo naturally-occurring cell death which is accentuated by the early removal of retinal ganglion cells. We show that providing BDNF or decreasing endogenous BDNF via competitive binding with soluble TrkB receptors in a whole-retina culture assay modulates the frequency of dying cells in the amacrine cell layer. Ganglion cells synthesize BDNF, and amacrine cells express TrkB receptors, suggesting a likely signaling mechanism.
Gap Junctions Mediate Bystander Cell Death in Developing Retina The Journal of Neuroscience : the Official Journal of the Society for Neuroscience. Jul, 2003 | Pubmed ID: 12878681 During development of the retina, programmed cell death helps to establish the final size and distribution of various cell classes in distinct layers of the tissue. Here we show that dying cells in the developing ganglion and inner nuclear layers are clustered spatially and that gap junction inhibitors decrease the clustering of dying cells. To confirm the role of gap junctions in cell death, we induced targeted cell death via intracellular cytochrome c (Cc) and examined the induced cells and their neighbors for apoptotic morphology or caspase-3 cleavage. These studies indicate that bystander killing extends to coupled cells. Quantitative studies of bystander killing were performed by scrape-loading retinas with Cc in the presence of rhodamine dextran (RD; to identify Cc-loaded cells) and by counting pyknotic cells in cryosections. Although only 1.5% of control scrape-loaded cells (RD alone) showed apoptotic morphology, 97% of Cc scrape-loaded cells were pyknotic. Moreover, bystander killing extended to neighboring cells, not labeled with RD, and was reduced significantly by the gap junction inhibitors octanol and carbenoxolone. We hypothesize that dying cells in the retina generate a gap junction-permeant apoptotic signal that mediates bystander killing. This novel finding of naturally occurring bystander cell death may have important implications in the histogenesis and pathology of the nervous system.
A Developmental Switch in the Expression of Aquaporin-4 and Kir4.1 from Horizontal to Müller Cells in Mouse Retina Investigative Ophthalmology & Visual Science. Oct, 2005 | Pubmed ID: 16186376 In adult retina, aquaporin-4 (AQP4) and inwardly rectifying K(+) (Kir4.1) channels localize to astrocyte and Müller cell membranes facing vascular and vitreous compartments, optimizing clearance of extracellular K(+) and water from the synaptic layers. However, it is unknown whether these channels are expressed at early developmental stages, before gliogenesis or angiogenesis take place in the neural retina. This study was conducted to determine the presence of AQP4 and Kir4.1 proteins in the developing mouse retina.
The Gap Junction Protein Connexin32 Interacts with the Src Homology 3/hook Domain of Discs Large Homolog 1 The Journal of Biological Chemistry. Mar, 2007 | Pubmed ID: 17284442 Scaffolding of membrane proteins is a common strategy for forming complexes of proteins, including some connexins, within membrane microdomains. Here we describe studies indicating that Cx32 interacts with a PDZ-containing scaffolding protein, Dlgh1 (Discs Large homolog 1). Initial screens of liver lysates using antibody arrays indicated an interaction between Cx32 and Dlgh1 that was confirmed using coimmunoprecipitation studies. Yeast two-hybrid complementation determined that the Cx32 bound via interaction with the SH3/Hook domain of Dlgh1. Confocal microscopy of liver sections revealed that Cx32 and Dlgh1 could colocalize in hepatocyte membranes in wild type mice. Examination of levels and localization of Dlgh1 in livers from Cx32 null mice indicate that, in the absence of Cx32, Dlgh1 was decreased, and the remainder was translocated from the hepatocyte membrane to the nucleus with some remaining in cytoplasmic compartments. This translocation was confirmed by Western blots comparing Dlgh1 levels in nuclear extracts from wild type and Cx32 null murine livers. Using SKHep cells stably transfected with Cx32 under the control of a tet-off promoter, we found that acute removal of Cx32 led to a decrease of membrane-localized Dlgh1 and an increase in the nuclear localization of this tumor suppressor protein. Together, these results suggest that loss of Cx32 alters the levels, localization, and interactions of the tumor suppressor protein Dlgh1, events known in other systems to alter cell cycle and increase tumorigenicity.
Reduced Retina Microglial Activation and Improved Optic Nerve Integrity with Minocycline Treatment in the DBA/2J Mouse Model of Glaucoma Investigative Ophthalmology & Visual Science. Apr, 2008 | Pubmed ID: 18385061 In the context of the retinal ganglion cell (RGC) axon degeneration in the optic nerve that occurs in glaucoma, microglia become activated, then phagocytic, and redistribute in the optic nerve head. The authors investigated the potential contribution of retinal microglia activation to glaucoma progression in the DBA/2J chronic mouse glaucoma model.
Early Microglia Activation in a Mouse Model of Chronic Glaucoma The Journal of Comparative Neurology. Mar, 2011 | Pubmed ID: 21246546 Changes in microglial cell activation and distribution are associated with neuronal decline in the central nervous system (CNS), particularly under pathological conditions. Activated microglia converge on the initial site of axonal degeneration in human glaucoma, yet their part in its pathophysiology remains unresolved. To begin with, it is unknown whether microglia activation precedes or is a late consequence of retinal ganglion cell (RGC) neurodegeneration. Here we address this critical element in DBA/2J (D2) mice, an established model of chronic inherited glaucoma, using as a control the congenic substrain DBA/2J Gpnmb(+/SjJ) (D2G), which is not affected by glaucoma. We analyzed the spatial distribution and timecourse of microglial changes in the retina, as well as within the proximal optic nerve prior to and throughout ages when neurodegeneration has been reported. Exclusively in D2 mice, we detected early microglia clustering in the inner central retina and unmyelinated optic nerve regions, with microglia activation peaking by 3 months of age. Between 5 and 8 months of age, activated microglia persisted and concentrated in the optic disc, but also localized to the retinal periphery. Collectively, our findings suggest microglia activation is an early alteration in the retina and optic nerve in D2 glaucoma, potentially contributing to disease onset or progression. Ultimately, detection of microglial activation may have value in early disease diagnosis, while modulation of microglial responses may alter disease progression.
Réduction Rapide De L'activation Des Microglies Par Irradiation Dans Un Modèle De Glaucome Chronique PloS One. 2012 | Pubmed ID: 22952717 Le glaucome est une maladie neurodégénérative qui entraîne le déclin progressif et de la mort ultime des cellules ganglionnaires rétiniennes (CGR). Alors que plusieurs facteurs de risque sont associés avec le glaucome, les mécanismes qui conduisent à l'apparition et la progression de la maladie restent inconnues. Analyse moléculaire dans divers modèles de glaucome a révélé l'implication des populations de cellules non neuronales, y compris les astrocytes, cellules gliales Mueller et la microglie, aux premiers stades du glaucome. Irradiation de haut-dose a été signalée pour avoir un effet protecteur à long terme significatif dans le modèle de souris DBA/2J (D2) de glaucome, bien que les bases cellulaires et moléculaires pour cet effet reste incertaine. En particulier, les effets aigus de l'irradiation sur les populations cellule spécifique, y compris les cellules non neuronales, dans la rétine de D2 et du système nerveux n'ont pas été évaluées. Nous rapportons ici que l'irradiation induit une réduction transitoire dans la prolifération des microglies dans la tête du nerf optique et glial limbe dans la première post-irradiation semaine. Cela s'est accompagné d'activation microgliale réduite, sans effet sur la gliose astrocytaire dans ces régions. À un stade ultérieur, nous confirmons que l'irradiation fortes doses au début des résultats tête souris dans l'amélioration de l'intégrité structurale axonale et la fonction de transport antérograde, sans réduction de la pression intraoculaire. Activation microgliale réduite induite par l'irradiation à des stades précoces est donc associée à la réduction de nerf optique et neurodégénérescence rétinienne chez la souris D2 du glaucome.
Neurodegeneration Severity is Anticipated by Early Microglia Alterations Monitored in Vivo in a Mouse Model of Chronic Glaucoma Disease Models & Mechanisms. Mar, 2015 | Pubmed ID: 25755083 Microglia serve key homeostatic roles, and respond to neuronal perturbation and decline with high spatiotemporal resolution. The course of all chronic CNS pathologies is thus paralleled by local microgliosis and microglia activation beginning at early stages. However, the possibility of using live monitoring of microglia during early disease progression to predict the severity of neurodegeneration has not been unexplored. Since the retina allows live tracking of fluorescent microglia in their intact niche, here we investigated their early changes in relation to later optic nerve neurodegeneration. Thus, we used the DBA/2J mouse model of inherited glaucoma, which develops progressive retinal ganglion cell degeneration of variable severity during aging, and thus represents a useful model to study pathogenic mechanisms of retinal ganglion cell decline similar to human glaucoma. We imaged CX3CR1(+/GFP) microglial cells in vivo at ages ranging from 1 to 5 months by confocal scanning laser ophthalmoscopy (cSLO) and quantified cell density and morphological activation. We detected early microgliosis at the optic nerve head (ONH), where axonopathy first manifests, and could track attenuation of this microgliosis induced by minocycline. We also observed heterogeneous and dynamic patterns of early microglia activation in the retina. When the same animals were aged and analyzed for the severity of optic nerve pathology at 10 months of age, we found a strong correlation with the levels of ONH microgliosis at 3 to 4 months. Our findings indicate that live imaging and monitoring the time course and levels of early retinal microgliosis and microglia activation in glaucoma could serve as indicators of future neurodegeneration severity.