scholarly journals Noninvasive two-photon imaging reveals retinyl ester storage structures in the eye

2004 ◽  
Vol 164 (3) ◽  
pp. 373-383 ◽  
Author(s):  
Yoshikazu Imanishi ◽  
Matthew L. Batten ◽  
David W. Piston ◽  
Wolfgang Baehr ◽  
Krzysztof Palczewski
Keyword(s):  
Pigment Epithelium ◽  
Retinal Pigment ◽  
Photoreceptor Cells ◽  
Retinyl Ester ◽  
Two Photon Microscopy ◽  
Two Photon ◽  
In Vivo Experiments ◽  
Essential Components ◽  
Intracellular Compartments

Visual sensation in vertebrates is triggered when light strikes retinal photoreceptor cells causing photoisomerization of the rhodopsin chromophore 11-cis-retinal to all-trans-retinal. The regeneration of preillumination conditions of the photoreceptor cells requires formation of 11-cis-retinal in the adjacent retinal pigment epithelium (RPE). Using the intrinsic fluorescence of all-trans-retinyl esters, noninvasive two-photon microscopy revealed previously uncharacterized structures (6.9 ± 1.1 μm in length and 0.8 ± 0.2 μm in diameter) distinct from other cellular organelles, termed the retinyl ester storage particles (RESTs), or retinosomes. These structures form autonomous all-trans-retinyl ester-rich intracellular compartments distinct from other organelles and colocalize with adipose differentiation-related protein. As demonstrated by in vivo experiments using wild-type mice, the RESTs participate in 11-cis-retinal formation. RESTs accumulate in Rpe65−/− mice incapable of carrying out the enzymatic isomerization, and correspondingly, are absent in the eyes of Lrat−/− mice deficient in retinyl ester synthesis. These results indicate that RESTs located close to the RPE plasma membrane are essential components in 11-cis-retinal production.

JAM-C maintains VEGR2 expression to promote retinal pigment epithelium cell survival under oxidative stress

2017 ◽  
Vol 117 (04) ◽  
pp. 750-757
Author(s):  
Xin Jia ◽  
Chen Zhao ◽  
Qishan Chen ◽  
Yuxiang Du ◽  
Lijuan Huang ◽  
...  
Keyword(s):  
Oxidative Stress ◽  
Retinal Pigment Epithelium ◽  
Cell Survival ◽  
Pigment Epithelium ◽  
Retinal Pigment ◽  
Retinal Pigment Epithelium Cell ◽  
Photoreceptor Cells ◽  
Rpe Cells

SummaryJunctional adhesion molecule-C (JAM-C) has been shown to play critical roles during development and in immune responses. However, its role in adult eyes under oxidative stress remains poorly understood. Here, we report that JAM-C is abundantly expressed in adult mouse retinae and choroids in vivo and in cultured retinal pigment epithelium (RPE) and photoreceptor cells in vitro. Importantly, both JAM-C expression and its membrane localisation are downregulated by H2O2-induced oxidative stress. Under H2O2-induced oxidative stress, JAM-C is critically required for the survival of human RPE cells. Indeed, loss of JAM-C by siRNA knockdown decreased RPE cell survival. Mechanistically, we show that JAM-C is required to maintain VEGFR2 expression in RPE cells, and VEGFR2 plays an important role in keeping the RPE cells viable since overexpression of VEGFR2 partially restored impaired RPE survival caused by JAM-C knockdown and increased RPE survival. We further show that JAM-C regulates VEGFR2 expression and, in turn, modulates p38 phosphorylation. Together, our data demonstrate that JAM-C plays an important role in maintaining VEGR2 expression to promote RPE cell survival under oxidative stress. Given the vital importance of RPE in the eye, approaches that can modulate JAM-C expression may have therapeutic values in treating diseases with impaired RPE survival.

The effects of intravitreally injected bevacizumab on the retina and retina pigment epithelium: experimental in-vivo electron microscopic study in intact versus vitrectomized eyes

Open Medicine ◽  
2010 ◽  
Vol 5 (6) ◽  
pp. 745-751 ◽  
Author(s):  
Nilufer Kocak ◽  
Candan Ozogul ◽  
Suleyman Kaynak ◽  
Ulker Sonmez ◽  
Mehmet Zengin ◽  
...  
Keyword(s):  
Pigment Epithelium ◽  
Retinal Pigment ◽  
Intravitreal Bevacizumab ◽  
Electron Microscopic Examination ◽  
Photoreceptor Cells ◽  
Control Group ◽  
Electron Microscopic ◽  
Tissue Samples ◽  
Electron Microscopes

AbstractTo analyze the retinal toxicity of bevacizumab at various doses both in vitrectomized and non-vitrectomized rabbit models. Twenty- eight rabbits were included in the study. Twenty- four rabbits were assigned to six groups, with 4 of the rabbits in the control group. The animals in Groups 1, 2 and 3 received bevacizumab at a dose of 0.3 mg, 0.5 mg and 1.5 mg /eye, respectively. The rabbits in Groups 4, 5 and 6 received intravitreal bevacizumab of 0.3 mg, 0.5 mg and 1.5mg/eye, respectively, after gas compression vitrectomy. Two weeks after the procedure, the rabbits were euthanized. Retina tissue samples were then obtained and examined with both light and electron microscopes. In Groups 1, 2 and 3 after bevacizumab injection, toxic degeneration in the photoreceptor and retinal pigment epithelium cells was observed via electron microscopic examination. The findings in Groups 4 and 5 were normal as compared to the control group. In Group 6, toxicity in the bipolar neurons and photoreceptor cells was noticed. Increased toxicity and retinal penetration were noticed in all administered doses of bevacizumab in the presence of vitreous. In addition, ocular toxicity occurred through the injection of the highest dose of bevacizumab after vitrectomy. It is possible that the bevacizumab dose and the, vitreous are as important as the drug half-life in the vitreous.

scholarly journals CRISPR-engineered mosaicism rapidly reveals that loss of Kcnj13 function in mice mimics human disease phenotypes

2015 ◽  
Vol 5 (1) ◽  
Author(s):  
Hua Zhong ◽  
Yiyun Chen ◽  
Yumei Li ◽  
Rui Chen ◽  
Graeme Mardon
Keyword(s):  
Gene Function ◽  
Pigment Epithelium ◽  
Retinal Pigment ◽  
Photoreceptor Cells ◽  
Mutant Mice ◽  
Wild Type ◽  
Cell Degeneration ◽  
Rpe Cells ◽  
Mosaic Expression

Abstract The era of genomics has demanded the development of more efficient and timesaving approaches to validate gene function in disease. Here, we utilized the CRISPR-Cas9 system to generate Kcnj13 mutant mice by zygote injection to verify the pathogenic role of human KCNJ13, mutations of which are thought to cause Leber congenital amaurosis (LCA), an early-onset form of blindness. We found that complete loss of Kcnj13 is likely postnatal lethal. Among surviving F0-generation mice examined, 80% show mosaic KCNJ13 expression in the retinal pigment epithelium (RPE). Mosaic expression correlates with decreased response to light and photoreceptor degeneration, indicating that Kcnj13 mutant mice mimic human KCNJ13-related LCA disease. Importantly, mosaic animals enable us to directly compare Kcnj13 mutant and wild-type RPE cells in the same eye. We found that RPE cells lacking KCNJ13 protein still survive but overlying photoreceptors exhibit cell degeneration. At the same time, wild-type RPE cells can rescue neighboring photoreceptor cells that overlie mutant RPE cells. These results suggest that KCNJ13 expression is required for RPE cells to maintain photoreceptor survival. Moreover, we show that CRISPR-Cas9 engineered mosaicism can be used to rapidly test candidate gene function in vivo.

scholarly journals Noninvasive two-photon microscopy imaging of mouse retina and retinal pigment epithelium through the pupil of the eye

2014 ◽  
Vol 20 (7) ◽  
pp. 785-789 ◽  
Author(s):  
Grazyna Palczewska ◽  
Zhiqian Dong ◽  
Marcin Golczak ◽  
Jennifer J Hunter ◽  
David R Williams ◽  
...  
Keyword(s):  
Retinal Pigment Epithelium ◽  
Pigment Epithelium ◽  
Retinal Pigment ◽  
Mouse Retina ◽  
Microscopy Imaging ◽  
Two Photon Microscopy ◽  
Two Photon

In vivo imaging of liver injury and regeneration by functional two-photon microscopy

2016 ◽  
Vol 54 (12) ◽  
pp. 1343-1404
Author(s):  
A Ghallab ◽  
R Reif ◽  
R Hassan ◽  
AS Seddek ◽  
JG Hengstler
Keyword(s):  
Liver Injury ◽  
In Vivo Imaging ◽  
Two Photon Microscopy ◽  
Two Photon

scholarly journals Ocular Toxoplasmosis: Mechanisms of Retinal Infection and Experimental Models

Parasitologia ◽  
2021 ◽  
Vol 1 (2) ◽  
pp. 50-60
Author(s):  
Veronica Rodriguez Fernandez ◽  
Giovanni Casini ◽  
Fabrizio Bruschi
Keyword(s):  
Ex Vivo ◽  
Cell Damage ◽  
Pigment Epithelium ◽  
Retinal Pigment ◽  
Treatment Strategies ◽  
Experimental Models ◽  
Ocular Toxoplasmosis ◽  
Cell Infection

Ocular toxoplasmosis (OT) is caused by the parasite Toxoplasma gondii and affects many individuals throughout the world. Infection may occur through congenital or acquired routes. The parasites enter the blood circulation and reach both the retina and the retinal pigment epithelium, where they may cause cell damage and cell death. Different routes of access are used by T. gondii to reach the retina through the retinal endothelium: by transmission inside leukocytes, as free parasites through a paracellular route, or after endothelial cell infection. A main feature of OT is the induction of an important inflammatory state, and the course of infection has been shown to be influenced by the host immunogenetics. On the other hand, there is evidence that the T. gondii phenotype also has an impact on the distribution of the pathology in different areas. Although considerable knowledge has been acquired on OT, a deeper knowledge of its mechanisms is necessary to provide new, more targeted treatment strategies. In particular, in addition to in vitro and in vivo experimental models, organotypic, ex vivo retinal explants may be useful in this direction.

scholarly journals OCT imaging of rod mitochondrial respiration in vivo

2021 ◽  
pp. 153537022110137
Author(s):  
Bruce A Berkowitz ◽  
Haohua Qian
Keyword(s):  
Signaling Pathway ◽  
Mitochondrial Respiration ◽  
Pigment Epithelium ◽  
Retinal Pigment ◽  
The Body ◽  
Subretinal Space ◽  
Outer Retina ◽  
Water Efflux ◽  
Resolution Imaging

There remains a need for high spatial resolution imaging indices of mitochondrial respiration in the outer retina that probe normal physiology and measure pathogenic and reversible conditions underlying loss of vision. Mitochondria are involved in a critical, but somewhat underappreciated, support system that maintains the health of the outer retina involving stimulus-evoked changes in subretinal space hydration. The subretinal space hydration light–dark response is important because it controls the distribution of vision-critical interphotoreceptor matrix components, including anti-oxidants, pro-survival factors, ions, and metabolites. The underlying signaling pathway controlling subretinal space water management has been worked out over the past 30 years and involves cGMP/mitochondria respiration/pH/RPE water efflux. This signaling pathway has also been shown to be modified by disease-generating conditions, such as hypoxia or oxidative stress. Here, we review recent advances in MRI and commercially available OCT technologies that can measure stimulus-evoked changes in subretinal space water content based on changes in the external limiting membrane-retinal pigment epithelium region. Each step within the above signaling pathway can also be interrogated with FDA-approved pharmaceuticals. A highlight of these studies is the demonstration of first-in-kind in vivo imaging of mitochondria respiration of any cell in the body. Future examinations of subretinal space hydration are expected to be useful for diagnosing threats to sight in aging and disease, and improving the success rate when translating treatments from bench-to-bedside.

The cytoskeletal elements of human retinal pigment epithelium: in vitro and in vivo

1988 ◽  
Vol 91 (2) ◽  
pp. 303-312
Author(s):  
N.M. McKechnie ◽  
M. Boulton ◽  
H.L. Robey ◽  
F.J. Savage ◽  
I. Grierson
Keyword(s):  
Retinal Pigment Epithelium ◽  
Pigment Epithelium ◽  
Retinal Pigment ◽  
Cytokeratin 18 ◽  
Rpe Cells ◽  
Human Retinal Pigment Epithelium ◽  
Cytoskeletal Elements

The cytoskeletal elements of normal (in situ) and cultured human retinal pigment epithelium (RPE) were studied by a variety of immunocytochemical techniques. Primary antibodies to vimentin and cytokeratins were used. Positive immunoreactivity for vimentin was obtained with in situ and cultured material. The pattern of reactivity obtained with antisera and monoclonals to cytokeratins was more complex. Cytokeratin immunoreactivity could be demonstrated in situ and in cultured cells. The pattern of cytokeratin expression was similar to that of simple or glandular epithelia. A monoclonal antibody that specifically recognizes cytokeratin 18 identified a population of cultured RPE cells that had particularly well-defined filamentous networks within their cytoplasm. Freshly isolated RPE was cytokeratin 18 negative by immunofluorescence, but upon culture cytokeratin 18 positive cells were identifiable. Cytokeratin 18 positive cells were identified in all RPE cultures (other than early primaries), regardless of passage number, age or sex of the donor. In post-confluent cultures cytokeratin 18 cells were identified growing over cytokeratin 18 negative cells, suggesting an association of cytokeratin 18 immunoreactivity with cell proliferation. Immunofluorescence studies of retinal scar tissue from two individuals revealed the presence of numerous cytokeratin 18 positive cells. These findings indicate that RPE cells can be identified by their cytokeratin immunoreactivity and that the overt expression of cytokeratin 18 may be associated with proliferation of human RPE both in vitro and in vivo.

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