Patterns of Distribution of Oxygen-Binding Globins, Neuroglobin and Cytoglobin in Human Retina

Abstract

Objective:To determine the distribution of 2 intracellular oxygen-carrying molecules, neuroglobin (NGB) and cytoglobin (CYGB), in specific retinal cell types of human retinas.Methods: Specific antibodies against NGB and CYGB were used in immunohistochemical studies to examine their distribution patterns in human retinal sections. Double-labeling studies were performed with the anti-NGB and anti-CYGB antibodies along with antibodies against neuronal (microtubule-associated protein 2, class III ␤-tubulin [TUJ1], protein kinase C alpha, calretinin) and glial (vimentin, glial fibrillary acid protein) markers. Confocal microscopy was used to examine the retinal sections.Results: Immunohistochemical analysis of human retinal tissue showed NGB and CYGB immunoreactivity in the ganglion cell layer, inner nuclear layer, inner and outer plexiform layers, and retinal pigment epithelium. Neuroglobin immunoreactivity was also present in the outer nuclear layer and photoreceptor inner segments. Neuroglobin and CYGB were coexpressed in the neurons in the ganglion cell layer and inner nuclear layer but not within glial cells.Conclusion: Neuroglobin and CYGB are colocalized within human retinal neurons and retinal pigment epithelium but not within glial cells.Clinical Relevance: Our results suggest that NGB and CYGB may serve a neuroprotective role as scavengers of reactive oxygen species and therefore should be considered when developing therapeutic strategies for treatment of hypoxia-related ocular diseases. Ophthalmol. 2008;126(11):1530-1536 Arch METHODS HUMAN TISSUEArchived eyes from 7 subjects (aged 1.5, 6, and 9 months and 6, 47, 58, and 60 years) were retrieved from the archives of the

Neuroglobin Is an Endogenous Neuroprotectant for Retinal Ganglion Cells against Glaucomatous Damage

“…Consistent with other reports, 8,[13][14][15] we detected moderate expression of NGB in the ganglion cell layer (GCL), inner plexiform layer (IPL), outer plexiform layer (OPL), and photoreceptor inner segment in retinal sections of adult mice using immunofluorescence labeling ( Figure 1, A-C). Taking advantage of our newly developed mouse model of glaucoma, we also examined the expression of NGB in the mouse retina under a diseased condition.…”

“…Our detection of expression of NGB in the GCL, IPL, and OPL of a normal mouse retina is consistent with reports of others. [13][14][15]50 In the present study, we used multiple methods to demonstrate that NGB levels are up-regulated in RGCs in vivo under a diseased condition involving oxidative stress and mitochondria dysfunction, suggesting its involvement in stress or in ocular hypertension.…”

“…8,9 NGB has been shown to act as an endogenous neuroprotective molecule that enhances neuronal survival under hypoxic-ischemic insults in the brain 10 -12 ; however, its physiological functions and molecular mode of actions are not fully understood. Of note, NGB is present at a 100-fold greater concentration in the retina than in the brain, 8,[13][14][15] suggesting that the retina may be its most important site of function; however, among the many unknown roles of NGB, functional significance of NGB expression in the retina has been largely unexplored. …”

Neuroglobin and Cytoglobin Distribution in the Anterior Eye Segment

“…Mouse monoclonal anti-Ngb antibody and the human recombinant Ngb protein used to produce this antibody were kindly provided by BioVendor (Candler, NC). Antibody specificity was verified using Western blot analysis on recombinant proteins, canine tissue samples (Ostojic et al 2006), and human retinal tissue samples (Ostojic et al in press). Anti-Ngb Abs detected recombinant Ngb protein at ?17 kDa, and a band of similar molecular mass was detected in protein samples from dog (Ostojic et al 2006) and human retinas (Ostojic et al in press).…”

Effect of light on global gene expression in the neuroglobin-deficient mouse retina

“…A number of studies have reported high levels of Ngb in the retina and adverse effects of Ngb knockdown on neuronal survival, leading the hypothesis that Ngb is important for retinal oxygen homeostasis and neuronal survival (7)(8)(9)(10)(11)(12)(13)(14)(30)(31)(32). Recently, Chan et al (13) found that transgenic overexpression of Ngb conferred protection against retinal ischemia via a decrease in oxidative stress levels.…”