scholarly journals Knockdown of Zebrafish Blood Vessel Epicardial Substance Results in Incomplete Retinal Lamination

2014 ◽  
Vol 2014 ◽  
pp. 1-9
Author(s):  
Yu-Ching Wu ◽  
Ruei-Feng Chen ◽  
Chia-Yang Liu ◽  
Fung Rong Hu ◽  
Chang-Jen Huang ◽  
...  
Keyword(s):  
Blood Vessel ◽  
Cell Polarity ◽  
Pigment Epithelium ◽  
Retinal Pigment ◽  
Photoreceptor Cells ◽  
Transgenic Zebrafish ◽  
Inner Plexiform Layer ◽  
Cellular Polarity ◽  
Apical Junctions ◽  
Retinal Lamination

Cell polarity during eye development determines the normal retinal lamination and differentiation of photoreceptor cells in the retina. In vertebrates, blood vessel epicardial substance (Bves) is known to play an important role in the formation and maintenance of the tight junctions essential for epithelial cell polarity. In the current study, we generated a transgenic zebrafish Bves (zbves) promoter-EGFP zebrafish line to investigate the expression pattern of Bves in the retina and to study the role ofzbvesin retinal lamination. Immunostaining with different specific antibodies from retinal cells and transmission electron microscopy were used to identify the morphological defects in normal and Bves knockdown zebrafish. In normal zebrafish, Bves is located at the apical junctions of embryonic retinal neuroepithelia during retinogenesis; later, it is strongly expressed around inner plexiform layer (IPL) and retinal pigment epithelium (RPE). In contrast, a loss of normal retinal lamination and cellular polarity was found with undifferentiated photoreceptor cells in Bves knockdown zebrafish. Herein, our results indicated that disruption of Bves will result in a loss of normal retinal lamination.

Multiple cell targets for melatonin action in Xenopus laevis retina: Distribution of melatonin receptor immunoreactivity

2001 ◽  
Vol 18 (5) ◽  
pp. 695-702 ◽  
Author(s):  
ALLAN F. WIECHMANN ◽  
CELESTE R. WIRSIG-WIECHMANN
Keyword(s):  
Xenopus Laevis ◽  
Direct Action ◽  
Pigment Epithelium ◽  
Retinal Pigment ◽  
Plexiform Layer ◽  
Amacrine Cells ◽  
Receptor Protein ◽  
Inner Plexiform Layer ◽  
Melatonin Receptor ◽  
Multiple Cell

In the retina of the African clawed frog (Xenopus laevis), melatonin is synthesized by the photoreceptors at night, and binds to receptors that likely mediate paracrine responses. Melatonin appears to alter the sensitivity of the retinal cells to light, and may play a key role in regulating important circadian events that occur in the eye. A polyclonal antibody was raised against a 13 amino acid peptide corresponding to a region of the third cytoplasmic loop of the Xenopus laevis Mel1c melatonin receptor. Western blot analysis revealed a major immunoreactive band of approximately 60 kD in neural retina and retinal pigment epithelium (RPE) membranes. Immunocytochemical labeling of sections of Xenopus eyes demonstrated intense melatonin receptor-like immunoreactivity in the inner plexiform layer (IPL). Immunolabeling with antibodies to glutamate decarboxylase (GAD) or tyrosine hydroxylase (TOH) appeared to co-localize with the melatonin receptor immunoreactivity in different sublaminas of the IPL. This suggests that both GABAergic and dopaminergic amacrine cells express melatonin receptor protein. There were also some melatonin receptor immunoreactive varicose fibers in the IPL that did not co-localize with either TOH or GAD, and may represent efferent fibers, since they could be followed into the optic nerve. Melatonin receptor immunoreactivity was also present on cell soma in the ganglion cell layer. Furthermore, a moderate level of melatonin receptor immunoreactivity was observed in the RPE and rod and cone photoreceptor cells. The presence of melatonin receptor immunoreactivity in these cells supports previous observations of melatonin receptor RNA expression in multiple cell types in the Xenopus retina. Expression of melatonin receptor protein in the photoreceptors suggests that melatonin may have a direct action on these cells.

Calcium gradients and light-evoked calcium changes outside rods in the intact cat retina

1994 ◽  
Vol 11 (4) ◽  
pp. 753-761 ◽  
Author(s):  
Ron P. Gallemore ◽  
Jian-Dong Li ◽  
Victor I. Govardovskii ◽  
Roy H. Steinberg
Keyword(s):  
Pigment Epithelium ◽  
Retinal Pigment ◽  
Plexiform Layer ◽  
Rapid Onset ◽  
Subretinal Space ◽  
Inner Plexiform Layer ◽  
Rod Outer Segments ◽  
Volume Increase ◽  
Cat Retina ◽  
Dependent Sources

AbstractWe have studied light-evoked changes in extracellular Ca2+ concentration in the intact cat eye using ion-sensitive double-barreled microelectrodes. Two prominent changes in Ca2+ concentration were observed that differed in retinal location. There was a light-evoked increase in accompanied by brief ON and OFF transients, which was maximal in the inner plexiform layer and was not further studied. There was an unexpected sustained light-evoked decrease in of relatively rapid onset and offset, which was maximal in the distalmost region of the subretinal space (SRS). in the SRS was 1.0 mM higher than in the vitreous humor during dark adaptation and this transretinal gradient disappeared during rod-saturating illumination. After correcting for the light-evoked increase in the volume of the SRS, an increase in the total Ca2+ content of the SRS during illumination was revealed, which presumably represents the Ca2+ released by rods. To explain the light-evoked changes, we used the diffusion model described in the accompanying paper (Li et al., 1994b), with the addition of light-dependent sources of Ca2+ at the retina/retinal pigment epithelium (RPE) border and rod outer segments. We conclude that a drop in around photoreceptors, which persists during illumination and reduces a transretinal Ca2+ gradient, is the combined effect of the light-evoked SRS volume increase, Ca2+ release from photoreceptors, and an unidentified mechanism(s), which is presumably Ca2+ transport by the RPE. The relatively rapid onset and offset of the decrease remains unexplained. These steady-state shifts in should have significant effects on photoreceptor function, especially adaptation.

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.

scholarly journals Phagocytosis of Retinal Rod and Cone Photoreceptors

Physiology ◽  
2010 ◽  
Vol 25 (1) ◽  
pp. 8-15 ◽  
Author(s):  
Brian M. Kevany ◽  
Krzysztof Palczewski
Keyword(s):  
Outer Segment ◽  
Photoreceptor Cell ◽  
Current Knowledge ◽  
Pigment Epithelium ◽  
Retinal Pigment ◽  
Photoreceptor Cells ◽  
Constant Length ◽  
Outer Segments ◽  
Retinal Rod ◽  
Rod And Cone Photoreceptors

Photoreceptor cells maintain a roughly constant length by continuously generating new outer segments from their base while simultaneously releasing mature outer segments engulfed by the retinal pigment epithelium (RPE). Thus postmitotic RPE cells phagocytose an immense amount of material over a lifetime, disposing of photoreceptor cell waste while retaining useful content. This review focuses on current knowledge of outer segment phagocytosis, discussing the steps involved along with their critical participants as well as how various perturbations in outer segment (OS) disposal can lead to retinopathies.

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 Role of retinal pigment epithelium-derived exosomes and autophagy in new blood vessel formation

2018 ◽  
Vol 22 (11) ◽  
pp. 5244-5256 ◽  
Author(s):  
Sandra Atienzar-Aroca ◽  
Gemma Serrano-Heras ◽  
Aida Freire Valls ◽  
Carmen Ruiz de Almodovar ◽  
Maria Muriach ◽  
...  
Keyword(s):  
Retinal Pigment Epithelium ◽  
Blood Vessel ◽  
Pigment Epithelium ◽  
Retinal Pigment ◽  
Blood Vessel Formation ◽  
Vessel Formation

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.

scholarly journals Vertebrate features revealed in the rudimentary eye of the Pacific hagfish (Eptatretus stoutii)

2020 ◽  
Author(s):  
Emily M. Dong ◽  
W. Ted Allison
Keyword(s):  
Ganglion Cells ◽  
Pigment Epithelium ◽  
Retinal Pigment ◽  
Photoreceptor Cells ◽  
List Type ◽  
Eye Evolution ◽  
The Pacific ◽  
Pigmented Epithelium ◽  
Cell Layers ◽  
Eptatretus Stoutii

SUMMARYHagfish eyes are markedly basic compared to the eyes of other vertebrates, lacking a pigmented epithelium, a lens, and a retinal architecture built of three cell layers – the photoreceptors, interneurons & ganglion cells. Concomitant with hagfish belonging to the earliest-branching vertebrate group (the jawless Agnathans), this lack of derived characters has prompted competing interpretations that hagfish eyes represent either a transitional form in the early evolution of vertebrate vision, or a regression from a previously elaborate organ. Here we show the hagfish retina is not extensively degenerating during its ontogeny, but instead grows throughout life via a recognizable Pax6+ ciliary marginal zone. The retina has a distinct layer of photoreceptor cells that appear to homogeneously express a single opsin of the rh1 rod opsin class. The epithelium that encompasses these photoreceptors is striking because it lacks the melanin pigment that is universally associated with animal vision; notwithstanding, we suggest this epithelium is a homolog of gnathosome Retinal Pigment Epithelium (RPE) based on its robust expression of RPE65 and its engulfment of photoreceptor outer segments. We infer that the hagfish retina is not entirely rudimentary in its wiring, despite lacking a morphologically distinct layer of interneurons: multiple populations of cells exist in the hagfish inner retina that differentially express markers of vertebrate retinal interneurons. Overall, these data clarify Agnathan retinal homologies, reveal characters that now appear to be ubiquitous across the eyes of vertebrates, and refine interpretations of early vertebrate visual system evolution.HIGHLIGHTSHagfish eyes are degenerate but not degenerating, i.e. rudimentary but growingRetinal interneurons discovered implying ancestral hagfish had derived retinas & visionDespite lacking pigment, a Retinal Pigmented Epithelium homolog functions in hagfishRevised synapomorphies illuminate the dimly lit origins of vertebrate eye evolutionGRAPHICAL ABSTRACT

scholarly journals Ultrastructural Circuitry in Retinal Cell Transplants to Rat Retina

1994 ◽  
Vol 5 (1) ◽  
pp. 17-29 ◽  
Author(s):  
Charles L. Zucker ◽  
Berndt Ehinger ◽  
Magdalene Seiler ◽  
Robert B. Aramant ◽  
Alan R. Adolph
Keyword(s):  
Bipolar Cell ◽  
Visual Information ◽  
Pigment Epithelium ◽  
Plexiform Layer ◽  
Photoreceptor Cells ◽  
Cell Types ◽  
Retinal Cell ◽  
Inner Plexiform Layer ◽  
Cell Transplants ◽  
Normal Differentiation

The development of five transplants of fetal retinal tissue to adult rat eyes was examined with the electron microscope. The transplants were of 9 to 10 weeks total age after conception in four cases and 20 weeks in one case. They were at stage E15 when transplanted. Transplants developed in both the epiretinal and subretinal spaces.The transplants were heterogeneously developed with some parts showing almost normal differentiation and others little. Subretinal transplants examined in this study were more developed than epiretinal grafts. Photoreceptor cells developed both inner and outer segments. Their synaptic terminals possessed output ribbon synapses with postsynaptic processes similar to those seen in normal retinas. In regions corresponding to the inner plexiform layer, the adult complement of synapses was seen, including advanced features such as serial synapses as well as reciprocal synapses at bipolar cell dyads. Incompletely differentiated synapses of both the amacrine and bipolar cell types were often observed, especially in the rat epiretinal transplants. Ganglion cell processes could not be identified with certainty.Although transplant cells were adjacent to host photoreceptor cells and pigment epithelium, obvious specializations or interactions were not observed. The experiments suggest that embryonic rat retinal cell transplants develop most or perhaps all of the structural components and neuronal circuitry necessary to transduce light and process some visual information.

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