scholarly journals Vertebrate ancient opsin photopigment spectra and the avian photoperiodic response

2011 ◽  
Vol 8 (2) ◽  
pp. 291-294 ◽  
Author(s):  
Wayne I. L. Davies ◽  
Michael Turton ◽  
Stuart N. Peirson ◽  
Brian K. Follett ◽  
Stephanie Halford ◽  
...  
Keyword(s):  
Ganglion Cells ◽  
Photoperiodic Response ◽  
Seasonal Reproduction ◽  
Retinal Ganglion ◽  
Functional Link ◽  
Deep Brain Photoreceptors ◽  
Deep Brain

In mammals, photoreception is restricted to cones, rods and a subset of retinal ganglion cells. By contrast, non-mammalian vertebrates possess many extraocular photoreceptors but in many cases the role of these photoreceptors and their underlying photopigments is unknown. In birds, deep brain photoreceptors have been shown to sense photic changes in daylength (photoperiod) and mediate seasonal reproduction. Nonetheless, the specific identity of the opsin photopigment ‘sensor’ involved has remained elusive. Previously, we showed that vertebrate ancient (VA) opsin is expressed in avian hypothalamic neurons and forms a photosensitive molecule. However, a direct functional link between VA opsin and the regulation of seasonal biology was absent. Here, we report the in vivo and in vitro absorption spectra ( λ max = ∼490 nm) for chicken VA photopigments. Furthermore, the spectral sensitivity of these photopigments match the peak absorbance of the avian photoperiodic response ( λ max = 492 nm) and permits maximum photon capture within the restricted light environment of the hypothalamus. Such a correspondence argues strongly that VA opsin plays a key role in regulating seasonal reproduction in birds.

scholarly journals Phosphorylation of DCC by Fyn mediates Netrin-1 signaling in growth cone guidance

2004 ◽  
Vol 167 (4) ◽  
pp. 687-698 ◽  
Author(s):  
Mayya Meriane ◽  
Joseph Tcherkezian ◽  
Christine A. Webber ◽  
Eric I. Danek ◽  
Ibtissem Triki ◽  
...  
Keyword(s):  
Molecular Mechanisms ◽  
Kinase Inhibitors ◽  
Ganglion Cells ◽  
Axon Outgrowth ◽  
Retinal Ganglion ◽  
Deleted In Colorectal Cancer ◽  
Commissural Neurons

Netrin-1 acts as a chemoattractant molecule to guide commissural neurons (CN) toward the floor plate by interacting with the receptor deleted in colorectal cancer (DCC). The molecular mechanisms underlying Netrin-1–DCC signaling are still poorly characterized. Here, we show that DCC is phosphorylated in vivo on tyrosine residues in response to Netrin-1 stimulation of CN and that the Src family kinase inhibitors PP2 and SU6656 block both Netrin-1–dependent phosphorylation of DCC and axon outgrowth. PP2 also blocks the reorientation of Xenopus laevis retinal ganglion cells that occurs in response to Netrin-1, which suggests an essential role of the Src kinases in Netrin-1–dependent orientation. Fyn, but not Src, is able to phosphorylate the intracellular domain of DCC in vitro, and we demonstrate that Y1418 is crucial for DCC axon outgrowth function. Both DCC phosphorylation and Netrin-1–induced axon outgrowth are impaired in Fyn−/− CN and spinal cord explants. We propose that DCC is regulated by tyrosine phosphorylation and that Fyn is essential for the response of axons to Netrin-1.

scholarly journals Neuroprotective Role of GLP-1 Analog for Retinal Ganglion Cells via PINK1/Parkin-Mediated Mitophagy in Diabetic Retinopathy

2021 ◽  
Vol 11 ◽  
Author(s):  
Huan-ran Zhou ◽  
Xue-fei Ma ◽  
Wen-jian Lin ◽  
Ming Hao ◽  
Xin-yang Yu ◽  
...  
Keyword(s):  
Diabetic Retinopathy ◽  
Retinal Ganglion Cells ◽  
Visual Information ◽  
Ganglion Cells ◽  
Neuroprotective Effect ◽  
Diabetic Rat ◽  
Retinal Ganglion

GLP-1 analogs have been widely used to treat patients with type 2 diabetes in recent years and studies have found that GLP-1 analogs have multiple organ benefits. However, the role of GLP-1 analogs in diabetic retinopathy (DR), a common complication of diabetes mellitus (DM), remains controversial. Retinal ganglion cells (RGCs) are the only afferent neurons responsible for transmitting visual information to the visual center and are vulnerable in the early stage of DR. Protection of RGC is vital for visual function. The incretin glucagon-like peptide-1 (GLP-1), which is secreted by L-cells after food ingestion, could lower blood glucose level through stimulating the release of insulin. In the present study, we evaluated the effects of GLP-1 analog on RGCs both in vitro and in vivo. We established diabetic rat models in vivo and applied an RGC-5 cell line in vitro. The results showed that in high glucose conditions, GLP-1 analog alleviated the damage of RGCs. In addition, GLP-1 analog prevented mitophagy through the PINK1/Parkin pathway. Here we demonstrated the neuroprotective effect of GLP-1 analog, which may be beneficial for retinal function, and we further elucidated a novel mechanism in GLP-1 analog-regulated protection of the retina. These findings may expand the multi-organ benefits of GLP-1 analogs and provide new insights for the prevention of DR.

scholarly journals Endothelin 1-induced retinal ganglion cell death is largely mediated by JUN activation

2020 ◽  
Vol 11 (9) ◽  
Author(s):  
Olivia J. Marola ◽  
Stephanie B. Syc-Mazurek ◽  
Gareth R. Howell ◽  
Richard T. Libby
Keyword(s):  
Transcription Factor ◽  
Molecular Mechanisms ◽  
Ganglion Cells ◽  
Retinal Vessel ◽  
Vessel Diameter ◽  
Retinal Ganglion ◽  
Retinal Ganglion Cell Death ◽  
Ganglion Cell Death

Abstract Glaucoma is a neurodegenerative disease characterized by loss of retinal ganglion cells (RGCs), the output neurons of the retina. Multiple lines of evidence show the endothelin (EDN, also known as ET) system is important in glaucomatous neurodegeneration. To date, the molecular mechanisms within RGCs driving EDN-induced RGC death have not been clarified. The pro-apoptotic transcription factor JUN (the canonical target of JNK signaling) and the endoplasmic reticulum stress effector and transcription factor DNA damage inducible transcript 3 (DDIT3, also known as CHOP) have been shown to act downstream of EDN receptors. Previous studies demonstrated that JUN and DDIT3 were important regulators of RGC death after glaucoma-relevant injures. Here, we characterized EDN insult in vivo and investigated the role of JUN and DDIT3 in EDN-induced RGC death. To accomplish this, EDN1 ligand was intravitreally injected into the eyes of wildtype, Six3-cre+Junfl/fl (Jun−/−), Ddit3 null (Ddit3−/−), and Ddit3−/−Jun−/− mice. Intravitreal EDN1 was sufficient to drive RGC death in vivo. EDN1 insult caused JUN activation in RGCs, and deletion of Jun from the neural retina attenuated RGC death after EDN insult. However, deletion of Ddit3 did not confer significant protection to RGCs after EDN1 insult. These results indicate that EDN caused RGC death via a JUN-dependent mechanism. In addition, EDN signaling is known to elicit potent vasoconstriction. JUN signaling was shown to drive neuronal death after ischemic insult. Therefore, the effects of intravitreal EDN1 on retinal vessel diameter and hypoxia were explored. Intravitreal EDN1 caused transient retinal vasoconstriction and regions of RGC and Müller glia hypoxia. Thus, it remains a possibility that EDN elicits a hypoxic insult to RGCs, causing apoptosis via JNK-JUN signaling. The importance of EDN-induced vasoconstriction and hypoxia in causing RGC death after EDN insult and in models of glaucoma requires further investigation.

Tafluprost protects rat retinal ganglion cells from apoptosis in vitro and in vivo

2009 ◽  
Vol 247 (10) ◽  
pp. 1353-1360 ◽  
Author(s):  
Akiyasu Kanamori ◽  
Maiko Naka ◽  
Masahide Fukuda ◽  
Makoto Nakamura ◽  
Akira Negi
Keyword(s):  
Retinal Ganglion Cells ◽  
Ganglion Cells ◽  
Retinal Ganglion

miR-223 induces retinal ganglion cells apoptosis and inflammation via decreasing HSP-70 in vitro and in vivo

2020 ◽  
Vol 104 ◽  
pp. 101747 ◽  
Author(s):  
Yun Ou-Yang ◽  
Zheng-Li Liu ◽  
Chun-Long Xu ◽  
Jia-Liang Wu ◽  
Jun Peng ◽  
...  
Keyword(s):  
Retinal Ganglion Cells ◽  
Ganglion Cells ◽  
Retinal Ganglion ◽  
Hsp 70 ◽  
Apoptosis And Inflammation

scholarly journals Role of Toxoplasma gondii Chloroquine Resistance Transporter in Bradyzoite Viability and Digestive Vacuole Maintenance

mBio ◽  
2019 ◽  
Vol 10 (4) ◽  
Author(s):  
Geetha Kannan ◽  
Manlio Di Cristina ◽  
Aric J. Schultz ◽  
My-Hang Huynh ◽  
Fengrong Wang ◽  
...  
Keyword(s):  
Toxoplasma Gondii ◽  
Chronic Infection ◽  
Chloroquine Resistance ◽  
Congenital Defects ◽  
Functional Link ◽  
Content Type ◽  
Chloroquine Resistance Transporter

ABSTRACT Toxoplasma gondii is a ubiquitous pathogen that can cause encephalitis, congenital defects, and ocular disease. T. gondii has also been implicated as a risk factor for mental illness in humans. The parasite persists in the brain as slow-growing bradyzoites contained within intracellular cysts. No treatments exist to eliminate this form of parasite. Although proteolytic degradation within the parasite lysosome-like vacuolar compartment (VAC) is critical for bradyzoite viability, whether other aspects of the VAC are important for parasite persistence remains unknown. An ortholog of Plasmodium falciparum chloroquine resistance transporter (CRT), TgCRT, has previously been identified in T. gondii. To interrogate the function of TgCRT in chronic-stage bradyzoites and its role in persistence, we knocked out TgCRT in a cystogenic strain and assessed VAC size, VAC digestion of host-derived proteins and parasite autophagosomes, and the viability of in vitro and in vivo bradyzoites. We found that whereas parasites deficient in TgCRT exhibit normal digestion within the VAC, they display a markedly distended VAC and their viability is compromised both in vitro and in vivo. Interestingly, impairing VAC proteolysis in TgCRT-deficient bradyzoites restored VAC size, consistent with a role for TgCRT as a transporter of products of digestion from the VAC. In conjunction with earlier studies, our current findings suggest a functional link between TgCRT and VAC proteolysis. This study provides further evidence of a crucial role for the VAC in bradyzoite persistence and a new potential VAC target to abate chronic Toxoplasma infection. IMPORTANCE Individuals chronically infected with the intracellular parasite Toxoplasma gondii are at risk of experiencing reactivated disease that can result in progressive loss of vision. No effective treatments exist for chronic toxoplasmosis due in part to a poor understanding of the biology underlying chronic infection and a lack of well-validated potential targets. We show here that a T. gondii transporter is functionally linked to protein digestion within the parasite lysosome-like organelle and that this transporter is necessary to sustain chronic infection in culture and in experimentally infected mice. Ablating the transporter results in severe bloating of the lysosome-like organelle. Together with earlier work, this study suggests the parasite’s lysosome-like organelle is vital for parasite survival, thus rendering it a potential target for diminishing infection and reducing the risk of reactivated disease.

scholarly journals Brazilian Green Propolis Protects against Retinal Damage In Vitro and In Vivo

2006 ◽  
Vol 3 (1) ◽  
pp. 71-77 ◽  
Author(s):  
Yuta Inokuchi ◽  
Masamitsu Shimazawa ◽  
Yoshimi Nakajima ◽  
Shinsuke Suemori ◽  
Satoshi Mishima ◽  
...  
Keyword(s):  
Oxidative Stress ◽  
Retinal Ganglion Cells ◽  
Ganglion Cells ◽  
Water Soluble ◽  
Retinal Damage ◽  
Retinal Ganglion ◽  
Neuroprotective Effects ◽  
Brazilian Green Propolis

Propolis, a honeybee product, has gained popularity as a food and alternative medicine. Its constituents have been shown to exert pharmacological (anticancer, antimicrobial and anti-inflammatory) effects. We investigated whether Brazilian green propolis exerts neuroprotective effects in the retinain vitroand/orin vivo.In vitro, retinal damage was induced by 24 h hydrogen peroxide (H2O2) exposure, and cell viability was measured by Hoechst 33342 and YO-PRO-1 staining or by a resazurin–reduction assay. Propolis inhibited the neurotoxicity and apoptosis induced in cultured retinal ganglion cells (RGC-5, a rat ganglion cell line transformed using E1A virus) by 24 h H2O2 exposure. Propolis also inhibited the neurotoxicity induced in RGC-5 cultures by staurosporine. Regarding the possible underlying mechanism, in pig retina homogenates propolis protected against oxidative stress (lipid peroxidation), as also did trolox (water-soluble vitamin E). In micein vivo, propolis (100 mg kg−1; intraperitoneally administered four times) reduced the retinal damage (decrease in retinal ganglion cells and in thickness of inner plexiform layer) induced by intravitrealin vivo N-methyl-d-aspartate injection. These findings indicate that Brazilian green propolis has neuroprotective effects against retinal damage bothin vitroandin vivo, and that a propolis-induced inhibition of oxidative stress may be partly responsible for these neuroprotective effects.

Latanoprost protects rat retinal ganglion cells from apoptosis in vitro and in vivo

2009 ◽  
Vol 88 (3) ◽  
pp. 535-541 ◽  
Author(s):  
Akiyasu Kanamori ◽  
Maiko Naka ◽  
Masahide Fukuda ◽  
Makoto Nakamura ◽  
Akira Negi
Keyword(s):  
Retinal Ganglion Cells ◽  
Ganglion Cells ◽  
Retinal Ganglion

scholarly journals Dexamethasone Provides Effective Immunosuppression for Improved Survival of Retinal Organoids after Epiretinal Transplantation

2019 ◽  
Vol 2019 ◽  
pp. 1-14 ◽  
Author(s):  
Bikun Xian ◽  
Ziming Luo ◽  
Kaijing Li ◽  
Kang Li ◽  
Mingjun Tang ◽  
...  
Keyword(s):  
Rhesus Monkey ◽  
Retinal Ganglion Cells ◽  
Ganglion Cells ◽  
Immunosuppressive Treatment ◽  
Retinal Ganglion ◽  
Chain Reaction ◽  
Immunological Rejection ◽  
Polymerase Chain

We investigated the efficacy of the immunosuppressants rapamycin (RAP) and dexamethasone (DEX) in improving the survival of retinal organoids after epiretinal transplantation. We first compared the immunosuppressive abilities of DEX and RAP in activated microglia in an in vitro setting. Following this, we used immunofluorescence, real-time polymerase chain reaction, and flow cytometry to investigate the effects of DEX and RAP on cells in the retinal organoids. Retinal organoids were then seeded onto poly(lactic-co-glycolic) acid (PLGA) scaffolds and implanted into rhesus monkey eyes (including a healthy individual and three monkeys with chronic ocular hypertension (OHT) induction) and subjected to different post-operative immunosuppressant treatments; 8 weeks after the experiment, histological examinations were carried out to assess the success of the different treatments. Our in vitro experiments indicated that both DEX and RAP treatments were equally effective in suppressing microglial activity. Although both immunosuppressants altered the morphologies of cells in the retinal organoids and caused a slight decrease in the differentiation of cells into retinal ganglion cells, the organoid cells retained their capacity to grow and differentiate into retinal tissues. Our in vivo experiments indicate that the retinal organoid can survive and differentiate into retinal tissues in a healthy rhesus monkey eye without immunosuppressive treatment. However, the survival and differentiation of these organoids in OHT eyes was successful only with the DEX treatment. RAP treatment was ineffective in preventing immunological rejection, and the retinal organoid failed to survive until the end of 8 weeks. DEX is likely a promising immunosuppressant to enhance the survival of epiretinal implants.

scholarly journals An alternative approach to produce versatile retinal organoids with accelerated ganglion cell development

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Philip E. Wagstaff ◽  
Anneloor L. M. A. ten Asbroek ◽  
Jacoline B. ten Brink ◽  
Nomdo M. Jansonius ◽  
Arthur A. B. Bergen
Keyword(s):  
Ganglion Cells ◽  
Cell Types ◽  
Retinal Cell ◽  
Specific Cell ◽  
Retinal Ganglion ◽  
In Vivo Models ◽  
Alternative Approach

AbstractGenetically complex ocular neuropathies, such as glaucoma, are a major cause of visual impairment worldwide. There is a growing need to generate suitable human representative in vitro and in vivo models, as there is no effective treatment available once damage has occured. Retinal organoids are increasingly being used for experimental gene therapy, stem cell replacement therapy and small molecule therapy. There are multiple protocols for the development of retinal organoids available, however, one potential drawback of the current methods is that the organoids can take between 6 weeks and 12 months on average to develop and mature, depending on the specific cell type wanted. Here, we describe and characterise a protocol focused on the generation of retinal ganglion cells within an accelerated four week timeframe without any external small molecules or growth factors. Subsequent long term cultures yield fully differentiated organoids displaying all major retinal cell types. RPE, Horizontal, Amacrine and Photoreceptors cells were generated using external factors to maintain lamination.

Sign in / Sign up

Export Citation Format

Share Document