scholarly journals Autophagy activated via GRP78 to alleviate endoplasmic reticulum stress for cell survival in blue light-mediated damage of A2E-laden RPEs

2019 ◽  
Vol 19 (1) ◽  
Author(s):  
Jingyang Feng ◽  
Yuhong Chen ◽  
Bing Lu ◽  
Xiangjun Sun ◽  
Hong Zhu ◽  
...  
Keyword(s):  
Endoplasmic Reticulum ◽  
Er Stress ◽  
Signaling Pathway ◽  
Blue Light ◽  
Pigment Epithelium ◽  
Retinal Pigment ◽  
Degenerative Diseases ◽  
Caspase 12 ◽  
Age Related ◽  
Retinal Degenerative Diseases

Abstract Background Retinal pigment epithelium cells (RPEs) are critical for maintaining retinal homeostasis. Accumulation of age-related lipofuscin, N-retinylidene-N-retinylethanolamine (A2E), makes RPEs vulnerable to blue light-mediated damage, which represents an initial cause of some retinal degenerative diseases. This study investigated the activation of autophagy and the signaling pathway involved in glucose-related protein 78 (GRP78) induced autophagy in blue light-mediated damage of A2E-laden RPEs. In addition, we explored whether autophagy could play a protective role by alleviating endoplasmic reticulum (ER) stress to promote RPEs survival. Methods RPEs were incubated with 25 μM A2E for 2 h and exposed to blue light for 20 min. The expression of ER stress-related apoptotic proteins, CHOP and caspase-12, as well as autophagy marker LC3 were measured by western blot analysis. Autophagosomes were observed by both transmission electron microscopy and immunofluorescence assays. GRP78 interference performed by short hairpin RNA (shRNA) was used to identify the signaling pathway involved in GRP78 induced autophagy. Cell death was assessed using TUNEL analysis. Results Treatment with A2E and blue light markedly increased the expression of ER stress-related apoptotic molecules CHOP and caspase-12. The activation of autophagy was recognized by observing autophagosomes at ultrastructural level. Additionally, punctate distributions of LC3 immunofluorescence and enhanced conversions of LC3-I to LC3-II were found in A2E and blue light-treated RPEs. Moreover, GRP78 interference reduced AMPK phosphorylation and promoted mTOR activity, thereby downregulating autophagy. In addition, the inhibition of autophagy made RPEs vulnerable to A2E and blue light damage. In contrast, the autophagy inducer rapamycin alleviated ER stress to promote RPEs survival. Conclusions GRP78 activates autophagy via AMPK/mTOR in blue light-mediated damage of A2E-laden RPEs in vitro. Autophagy may be a vital endogenous cytoprotective process to alleviate stress for RPEs survival in retinal degenerative diseases.

Retinal Pigment Epithelium Regeneration by Induced Pluripotent Stem Cells; Therapeutic and Modelling Approaches on Retinal Degenerative Diseases

2021 ◽  
Vol 16 ◽  
Author(s):  
Shadi Setayeshi ◽  
Seyed Ahmad Rasoulinejad
Keyword(s):  
Retinal Pigment Epithelium ◽  
Disease Modeling ◽  
Pigment Epithelium ◽  
Retinal Pigment ◽  
Degenerative Diseases ◽  
Rpe Cells ◽  
Age Related ◽  
Retinal Degenerative Diseases ◽  
Epithelium Regeneration ◽  
Induced Pluripotent

Abstract: Retinal Degenerative Diseases [RDDs] are irreversible ocular damages categorized as retinopathies. RDDs affects about 0.05% of individuals worldwide. The degenerations of RPE cells are involved in inherited and age-related RDDs. After the invention of induced Pluripotent Stem Cell [iPSC] by Yamanaka, a promising window has been opened to regenerative medicine and disease modeling. Retinal pigment epithelium [RPE] degeneration related-RDDs are also affected by iPSCs. IPSC-derived RPE cells created a novel method for treating the RPE degeneration related-RDDs and retinal diseases modeling regarding finding a new therapeutic approach or drug development. There are various studies based on iPSC-derived RPE cells reporting the investigation of the role of a specific mutation, protein, signaling pathway, etc., responsible for a type of RDD. Furthermore, iPSC-based RPE therapy is expanded to include some clinical trials. Despite the incredible growth rate in iPSC-based studies in RPE-related diseases, there are some challenges, i.e., teratoma formation potential of iPSCs, the highly-cost procedure of iPSC-based regeneration of RPEs, lack of a universal protocol or cellular product applicable in all patients, etc. This article reviews the iPSC-based RPE generation and their therapeutic applications, studies on RPE-related molecular and cellular pathophysiologic features of RDD in the iPSC-based models, future perspectives, and the challenges ahead.

scholarly journals Resveratrol Modulates SIRT1 and DNMT Functions and Restores LINE-1 Methylation Levels in ARPE-19 Cells under Oxidative Stress and Inflammation

2018 ◽  
Vol 19 (7) ◽  
pp. 2118 ◽  
Author(s):  
Andrea Maugeri ◽  
Martina Barchitta ◽  
Maria Mazzone ◽  
Francesco Giuliano ◽  
Guido Basile ◽  
...  
Keyword(s):  
Oxidative Stress ◽  
Retinal Pigment ◽  
Sirtuin 1 ◽  
Age Related Macular Degeneration ◽  
Degenerative Diseases ◽  
P Values ◽  
Sirt1 Expression ◽  
Inflammatory Conditions ◽  
Age Related ◽  
Retinal Degenerative Diseases

The role of epigenetic alterations in the pathogenesis of retinal degenerative diseases, including age-related macular degeneration (AMD), has been pending so far. Our study investigated the effect of oxidative stress and inflammation on DNA methyltransferases (DNMTs) and Sirtuin 1 (SIRT1) functions, as well as on long interspersed nuclear element-1 (LINE-1) methylation, in human retinal pigment epithelial (ARPE-19) cells. Therefore, we evaluated whether treatment with resveratrol may modulate DNMT and SIRT1 functions and restore changes in LINE-1 methylation. Cells were treated with 25 mU/mL glucose oxidase (GOx) or 10 µg/mL lipopolysaccharide (LPS) to mimic oxidative or inflammatory conditions, respectively. Oxidative stress decreased DNMT1, DNMT3a, DNMT3b, and SIRT1 expression (p-values < 0.05), as well as total DNMTs (−28.5%; p < 0.0001) and SIRT1 (−29.0%; p < 0.0001) activities. Similarly, inflammatory condition decreased DNMT1 and SIRT1 expression (p-values < 0.05), as well as total DNMTs (−14.9%; p = 0.007) and SIRT1 (−20.1%; p < 0.002) activities. Interestingly, GOx- and LPS-treated cells exhibited lower LINE-1 methylation compared to controls (p-values < 0.001). We also demonstrated that treatment with 10 μM resveratrol for 24 h counteracted the detrimental effect on DNMT and SIRT1 functions, and LINE-1 methylation, in cells under oxidative and inflammatory conditions. However, further studies should explore the perspectives of resveratrol as a suitable strategy for the prevention and/or treatment of retinal degenerative diseases.

scholarly journals Embryonic stem cell microenvironment enhances proliferation of human retinal pigment epithelium cells by activating the PI3K signaling pathway

2020 ◽  
Vol 11 (1) ◽  
Author(s):  
Jiahui Liu ◽  
Liu Yang ◽  
Xiaoran Wang ◽  
Shoubi Wang ◽  
Zheqian Huang ◽  
...  
Keyword(s):  
Gene Expression ◽  
Stem Cell ◽  
Signaling Pathway ◽  
Pigment Epithelium ◽  
Retinal Pigment ◽  
Embryonic Stem ◽  
Age Related Macular Degeneration ◽  
Pi3k Signaling ◽  
Age Related ◽  
Pi3k Signaling Pathway

Abstract Background Retinal pigment epithelium (RPE) replacement has been proposed as an efficacious treatment for age-related macular degeneration (AMD), which is the primary cause of vision loss in the elderly worldwide. The embryonic stem cell (ESC) microenvironment has been demonstrated to enable mature cells to gain a powerful proliferative ability and even enhance the stem/progenitor phenotype via activation of the phosphoinositide 3-kinase (PI3K) signaling pathway. As the PI3K signaling pathway plays a pivotal role in proliferation and homeostasis of RPE, we hypothesize that the stemness and proliferative capability of RPE can be enhanced by the ESC microenvironment via activation of the PI3K signaling pathway. Methods To investigate whether the ESC microenvironment improves the stem cell phenotype and proliferation properties of human RPE (hRPE) cells by regulating the PI3K signaling pathway, primary hRPE cells were cocultured with either ESCs or human corneal epithelial cells (CECs) for 72 h, after which their proliferation, apoptosis, cell cycle progression, and colony formation were assayed to evaluate changes in their biological characteristics. Gene expression was detected by real-time PCR and protein levels were determined by western blotting or immunofluorescence. LY294002, an antagonist of the PI3K signaling pathway, was used to further confirm the mechanism involved. Results In comparison to hRPE cells cultured alone, hRPE cells cocultured with ESCs had an increased proliferative capacity, reduced apoptotic rate, and higher colony-forming efficiency. The expression of the stem cell-associated marker KLF4 and the differentiation marker CRALBP increased and decreased, respectively, in hRPE cells isolated from the ESC coculture. Furthermore, PI3K pathway-related genes were significantly upregulated in hRPE cells after exposure to ESCs. LY294002 reversed the pro-proliferative effect of ESCs on hRPE cells. In contrast, CECs did not share the ability of ESCs to influence the biological behavior and gene expression of hRPE cells. Conclusions Our findings indicate that the ESC microenvironment enhances stemness and proliferation of hRPE cells, partially via activation of the PI3K signaling pathway. This study may have a significant impact and clinical implication on cell therapy in regenerative medicine, specifically for age-related macular degeneration.

scholarly journals The HDAC/HSP90 Inhibitor G570 Attenuated Blue Light-Induced Cell Migration in RPE Cells and Neovascularization in Mice through Decreased VEGF Production

Molecules ◽  
2021 ◽  
Vol 26 (14) ◽  
pp. 4359
Author(s):  
Tai-Ju Hsu ◽  
Kunal Nepali ◽  
Chi-Hao Tsai ◽  
Zuha Imtiyaz ◽  
Fan-Li Lin ◽  
...  
Keyword(s):  
Cell Migration ◽  
Blue Light ◽  
Pigment Epithelium ◽  
Retinal Pigment ◽  
Hsp90 Inhibitor ◽  
Age Related Macular Degeneration ◽  
Rpe Cells ◽  
Age Related ◽  
Proven Efficacy ◽  
Wet Amd

Age-related macular degeneration (AMD) occurs due to an abnormality of retinal pigment epithelium (RPE) cells that leads to gradual degeneration of the macula. Currently, AMD drug pipelines are endowed with limited options, and anti-VEGF agents stand as the dominantly employed therapy. Despite the proven efficacy of such agents, the evidenced side effects associated with their use underscore the need to elucidate other mechanisms involved and identify additional molecular targets for the sake of therapy improvement. The previous literature provided us with a solid rationale to preliminarily explore the potential of selective HDAC6 and HSP90 inhibitors to treat wet AMD. Rather than furnishing single-target agents (either HDAC6 or HSP90 inhibitor), this study recruited scaffolds endowed with the ability to concomitantly modulate both targets (HDAC6 and HSP90) for exploration. This plan was anticipated to accomplish the important goal of extracting amplified benefits via dual inhibition (HDAC6/HSP90) in wet AMD. As a result, G570 (indoline-based hydroxamate), a dual selective HDAC6-HSP90 inhibitor exerting its effects at micromolar concentrations, was pinpointed in the present endeavor to attenuate blue light-induced cell migration and retinal neovascularization by inhibiting VEGF production. In addition to the identification of a potential chemical tool (G570), the outcome of this study validates the candidate HDAC6-HSP90 as a compelling target for the development of futuristic therapeutics for wet AMD.

scholarly journals Protective Mechanisms of the Mitochondrial-Derived Peptide Humanin in Oxidative and Endoplasmic Reticulum Stress in RPE Cells

2017 ◽  
Vol 2017 ◽  
pp. 1-11 ◽  
Author(s):  
Leonid Minasyan ◽  
Parameswaran G. Sreekumar ◽  
David R. Hinton ◽  
Ram Kannan
Keyword(s):  
Oxidative Stress ◽  
Endoplasmic Reticulum ◽  
Cell Death ◽  
Er Stress ◽  
Apoptotic Cell ◽  
Retinal Pigment ◽  
Age Related Macular Degeneration ◽  
Ros Generation ◽  
Rpe Cells ◽  
Age Related

Age-related macular degeneration (AMD) is the leading cause of severe and irreversible vision loss and is characterized by progressive degeneration of the retina resulting in loss of central vision. The retinal pigment epithelium (RPE) is a critical site of pathology of AMD. Mitochondria and the endoplasmic reticulum which lie in close anatomic proximity to each other are targets of oxidative stress and endoplasmic reticulum (ER) stress, respectively, and contribute to the progression of AMD. The two organelles exhibit close interactive function via various signaling mechanisms. Evidence for ER-mitochondrial crosstalk in RPE under ER stress and signaling pathways of apoptotic cell death is presented. The role of humanin (HN), a prominent member of a newly discovered family of mitochondrial-derived peptides (MDPs) expressed from an open reading frame of mitochondrial 16S rRNA, in modulation of ER and oxidative stress in RPE is discussed. HN protected RPE cells from oxidative and ER stress-induced cell death by upregulation of mitochondrial GSH, inhibition of ROS generation, and caspase 3 and 4 activation. The underlying mechanisms of ER-mitochondrial crosstalk and modulation by exogenous HN are discussed. The therapeutic use of HN and related MDPs could potentially prove to be a valuable approach for treatment of AMD.

scholarly journals FTO alleviates Aβ1-40 induced retinal pigment epithelium degeneration via PKA/CREB signaling pathway

2020 ◽  
Author(s):  
YiFan Hu ◽  
JieQiong Chen ◽  
JunRan Sun ◽  
YuWei Wang ◽  
PeiRong Huang ◽  
...  
Keyword(s):  
Retinal Pigment Epithelium ◽  
Signaling Pathway ◽  
Pigment Epithelium ◽  
Retinal Pigment ◽  
Amyloid Β ◽  
Age Related Macular Degeneration ◽  
Fundus Photography ◽  
Molecular Characteristics ◽  
Cell Degeneration ◽  
Age Related

Abstract Background Amyloid-β (Aβ), a component of age-related macular degeneration (AMD) hallmark drusen, induces retinal pigment epithelium (RPE) cell degeneration and promotes the progress of AMD. Evidence shows that epigenetics mechanism is involved in the regulation of AMD. In this study, we aimed to investigate the roles of N6-methyladenosine (m6A) and its demethylase the fat mass and obesity-associated gene (FTO) in Aβ-mediated degeneration. Methods The molecular characteristics and morphology of FTO were examined by quantitative Real-Time PCR (qRT-PCR), Western blot and immunofluorescence. Inhibition of FTO was conducted to analyze its function on cell survival. Ocular Coherence Tomography and Fundus Photography was performed to evaluate the fundus of animal models. m6A-mRNA Epi-transcriptomic microarray, bioinformatics analysis and experimental verification were used to explore the potential molecular mechanism and signaling pathway. Results We found overexpression of FTO in Aβ model and demonstrated that inhibition of FTO by the sodium form of Meclofenamic acid (MA1) aggravated RPE impairment. Mechanistically, we identified protein kinase A (PKA) as FTO’s mediating target and found that FTO epigenetically demethylated PKA mRNA and decreased PKA expression, leading to suppressed PKA/ cyclin AMP-responsive element binding (CREB) signaling pathway. Moreover, inhibition of FTO promoted PKA/CREB signaling pathway inducing greater RPE degeneration and death. Conclusions These data demonstrated the functional significance of FTO in Aβ-induced RPE degeneration and the regulatory mechanism of PKA/CREB signaling pathway, implying FTO as a potentially therapeutic target for AMD.

scholarly journals Mitochondrial Dysfunction and Endoplasmic Reticulum Stress in Age Related Macular Degeneration, Role in Pathophysiology, and Possible New Therapeutic Strategies

Antioxidants ◽  
2021 ◽  
Vol 10 (8) ◽  
pp. 1170
Author(s):  
Valentina Bilbao-Malavé ◽  
Jorge González-Zamora ◽  
Miriam de la Puente ◽  
Sergio Recalde ◽  
Patricia Fernandez-Robredo ◽  
...  
Keyword(s):  
Endoplasmic Reticulum ◽  
Endoplasmic Reticulum Stress ◽  
Mitochondrial Dysfunction ◽  
Macular Degeneration ◽  
Pigment Epithelium ◽  
Retinal Pigment ◽  
Developed Countries ◽  
Age Related Macular Degeneration ◽  
Age Related ◽  
Increased Risk

Age related macular degeneration (AMD) is the main cause of legal blindness in developed countries. It is a multifactorial disease in which a combination of genetic and environmental factors contributes to increased risk of developing this vision-incapacitating condition. Oxidative stress plays a central role in the pathophysiology of AMD and recent publications have highlighted the importance of mitochondrial dysfunction and endoplasmic reticulum stress in this disease. Although treatment with vascular endothelium growth factor inhibitors have decreased the risk of blindness in patients with the exudative form of AMD, the search for new therapeutic options continues to prevent the loss of photoreceptors and retinal pigment epithelium cells, characteristic of late stage AMD. In this review, we explain how mitochondrial dysfunction and endoplasmic reticulum stress participate in AMD pathogenesis. We also discuss a role of several antioxidants (bile acids, resveratrol, melatonin, humanin, and coenzyme Q10) in amelioration of AMD pathology.

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