c-Jun-mediated microRNA-302d-3p induces RPE dedifferentiation by targeting p21Waf1/Cip1

Microglial repopulation restricts ocular inflammation and choroidal neovascularization in mice

Introduction

Age-related macular degeneration (AMD) is a prevalent, chronic and progressive retinal degenerative disease characterized by an inflammatory response mediated by activated microglia accumulating in the retina. In this study, we demonstrate the therapeutically effects and the underlying mechanisms of microglial repopulation in the laser-induced choroidal neovascularization (CNV) model of exudative AMD.

Methods

The CSF1R inhibitor PLX3397 was used to establish a treatment paradigm for microglial repopulation in the retina. Neovascular leakage and neovascular area were examined by fundus fluorescein angiography (FFA) and immunostaining of whole-mount RPE-choroid-sclera complexes in CNV mice receiving PLX3397. Altered cellular senescence was measured by beta-galactosidase (SA-β-gal) activity and p16INK4a expression. The effect and mechanisms of repopulated microglia on leukocyte infiltration and the inflammatory response in CNV lesions were analyzed.

Results

We showed that ten days of the CSF1R inhibitor PLX3397 treatment followed by 11 days of drug withdrawal was sufficient to stimulate rapid repopulation of the retina with new microglia. Microglial repopulation attenuated pathological choroid neovascularization and dampened cellular senescence in CNV lesions. Repopulating microglia exhibited lower levels of activation markers, enhanced phagocytic function and produced fewer cytokines involved in the immune response, thereby ameliorating leukocyte infiltration and attenuating the inflammatory response in CNV lesions.

Discussion

The microglial repopulation described herein are therefore a promising strategy for restricting inflammation and choroidal neovascularization, which are important players in the pathophysiology of AMD.

The miR-302/367 cluster: Aging, inflammation, and cancer

MicroRNAs (miRNAs) are a class of noncoding RNAs that occupy a significant role in biological processes as important regulators of intracellular homeostasis. First, we will discuss the biological genesis and functions of the miR-302/367 cluster, including miR-302a, miR-302b, miR-302c, miR-302d, and miR-367, as well as their roles in physiologically healthy tissues. The second section of this study reviews the progress of the miR-302/367 cluster in the treatment of cancer, inflammation, and diseases associated with aging. This cluster's aberrant expression in cells and/or tissues exhibits similar or different effects in various diseases through molecular mechanisms such as proliferation, apoptosis, cycling, drug resistance, and invasion. This article also discusses the upstream and downstream regulatory networks of miR-302/367 clusters and their related mechanisms. Particularly because studies on the upstream regulatory molecules of miR-302/367 clusters, which include age-related macular degeneration, myocardial infarction, and cancer, have become more prevalent in recent years. MiR-302/367 cluster can be an important therapeutic target and the use of miRNAs in combination with other molecular markers may improve diagnostic or therapeutic capabilities, providing unique insights and a more dynamic view of various diseases. It is noted that miRNAs can be an important bio-diagnostic target and offer a promising method for illness diagnosis, prevention, and treatment.

DAPL1 prevents epithelial-mesenchymal transition in the retinal pigment epithelium and experimental proliferative vitreoretinopathy

Epithelial-mesenchymal transition (EMT) of the retinal pigment epithelium (RPE) is a hallmark of the pathogenesis of proliferative vitreoretinopathy (PVR) that can lead to severe vision loss. Nevertheless, the precise regulatory mechanisms underlying the pathogenesis of PVR remain largely unknown. Here, we show that the expression of death-associated protein-like 1 (DAPL1) is downregulated in PVR membranes and that DAPL1 deficiency promotes EMT in RPE cells in mice. In fact, adeno-associated virus (AAV)-mediated DAPL1 overexpression in RPE cells of Dapl1-deficient mice inhibited EMT in physiological and retinal-detachment states. In a rabbit model of PVR, ARPE-19 cells overexpressing DAPL1 showed reduced ability to induce experimental PVR, and AAV-mediated DAPL1 delivery attenuated the severity of experimental PVR. Furthermore, a mechanistic study revealed that DAPL1 promotes P21 phosphorylation and its stabilization partially through NFκB (RelA) in RPE cells, whereas the knockdown of P21 led to neutralizing effects on DAPL1-dependent EMT inhibition and enhanced the severity of experimental PVR. These results suggest that DAPL1 acts as a novel suppressor of RPE-EMT and has an important role in antagonizing the pathogenesis of experimental PVR. Hence, this finding has implications for understanding the mechanism of and potential therapeutic applications for PVR.

The Role of Dysregulated miRNAs in the Pathogenesis, Diagnosis and Treatment of Age-Related Macular Degeneration

Age-related macular degeneration (AMD) is an eye disease causing damage to the macular region of the retina where most of the photoreceptors responsible for central visual acuity are located. MicroRNAs (miRNAs) are small single-stranded non-coding RNA molecules that negatively regulate genes by silent post-transcriptional gene expressions. Previous studies have shown that changes in specific miRNAs are involved in the pathogenesis of eye diseases, including AMD. Altered expressions of miRNAs are related to disturbances of regulating oxidative stress, inflammation, angiogenesis, apoptosis and phagocytosis, which are known factors in the pathogenesis of AMD. Moreover, dysregulation of miRNA is involved in drusen formation. Thus, miRNAs may be used as potential molecular biomarkers for the disease and, furthermore, tailoring therapeutics to particular disturbances in miRNAs may, in the future, offer hope to prevent irreversible vision loss. In this review, we clarify the current state of knowledge about the influence of miRNA on the pathogenesis, diagnosis and treatment of AMD. Our study material consisted of publications, which were found in PubMed, Google Scholar and Embase databases using “Age-related macular degeneration”, “miRNA”, “AMD biomarkers”, “miRNA therapeutics” and “AMD pathogenesis” as keywords. Paper search was limited to articles published from 2011 to date. In the section “Retinal, circulating and vitreous body miRNAs found in human studies”, we limited the search to studies with patients published in 2016–2021.

MicroRNAs as Regulators of Phagocytosis

MicroRNAs (miRNAs) are short non-coding RNAs that regulate gene expression and thus act as important regulators of cellular phenotype and function. As their expression may be dysregulated in numerous diseases, they are of interest as biomarkers. What is more, attempts of modulation of some microRNAs for therapeutic reasons have been undertaken. In this review, we discuss the current knowledge regarding the influence of microRNAs on phagocytosis, which may be exerted on different levels, such as through macrophages polarization, phagosome maturation, reactive oxygen species production and cytokines synthesis. This phenomenon plays an important role in numerous pathological conditions.

MicroRNA regulation of critical retinal pigment epithelial functions

MicroRNAs are short, evolutionarily conserved noncoding RNAs that are critical for the control of normal cellular physiology. In the retina, photoreceptors are highly specialized neurons that transduce light into electrical signals. Photoreceptors, however, are unable to process visual stimuli without the support of the retinal pigment epithelium (RPE). The RPE performs numerous functions to aid the retina, including the generation of visual chromophore and metabolic support. Recent work has underscored how microRNAs enable vision through their contributions to RPE functions. This review focuses on the biogenesis and control of microRNAs in rodents and humans, the roles microRNAs play in RPE function and degeneration, and how microRNAs could serve as potential therapeutics and biomarkers for visual diseases.

The Impact of miRNAs in Health and Disease of Retinal Pigment Epithelium

MicroRNAs (miRNAs), a class of non-coding RNAs, are essential key players in the control of biological processes in both physiological and pathological conditions. miRNAs play important roles in fine tuning the expression of many genes, which often have roles in common molecular networks. miRNA dysregulation thus renders cells vulnerable to aberrant fluctuations in genes, resulting in degenerative diseases. The retinal pigment epithelium (RPE) is a monolayer of polarized pigmented epithelial cells that resides between the light-sensitive photoreceptors (PR) and the choriocapillaris. The demanding physiological functions of RPE cells require precise gene regulation for the maintenance of retinal homeostasis under stress conditions and the preservation of vision. Thus far, our understanding of how miRNAs function in the homeostasis and maintenance of the RPE has been poorly addressed, and advancing our knowledge is central to harnessing their potential as therapeutic agents to counteract visual impairment. This review focuses on the emerging roles of miRNAs in the function and health of the RPE and on the future exploration of miRNA-based therapeutic approaches to counteract blinding diseases.

A Multi-Omics Approach Identifies Key Regulatory Pathways Induced by Long-Term Zinc Supplementation in Human Primary Retinal Pigment Epithelium

In age-related macular degeneration (AMD), both systemic and local zinc levels decline. Elevation of zinc in clinical studies delayed the progression to end-stage AMD. However, the molecular pathways underpinning this beneficial effect are not yet identified. In this study, we used differentiated primary human fetal retinal pigment epithelium (RPE) cultures and long-term zinc supplementation to carry out a combined transcriptome, proteome and secretome analysis from three genetically different human donors. After combining significant differences, we identified the complex molecular networks using Database for Annotation, Visualization and Integrated Discovery (DAVID) and Ingenuity Pathway Analysis (IPA). The cell cultures from the three donors showed extensive pigmentation, development of microvilli and basal infoldings and responded to zinc supplementation with an increase in transepithelial electrical resistance (TEER) (apical supplementation: 443.2 ± 79.3%, basal supplementation: 424.9 ± 116.8%, compared to control: 317.5 ± 98.2%). Significant changes were observed in the expression of 1044 genes, 151 cellular proteins and 124 secreted proteins. Gene set enrichment analysis revealed changes in specific molecular pathways related to cell adhesion/polarity, extracellular matrix organization, protein processing/transport, and oxidative stress response by zinc and identified a key upstream regulator effect similar to that of TGFB1.

LINC00167 Regulates RPE Differentiation by Targeting the miR-203a-3p/SOCS3 Axis

Increasing evidence has indicated that long non-coding RNAs (lncRNAs) play significant roles in various diseases; however, their roles in age-related macular degeneration (AMD) remain unclear. Dedifferentiation and dysfunction of retinal pigment epithelium (RPE) cells have been shown to contribute to AMD etiology in several studies. Herein, we found that lncRNA LINC00167 was downregulated in RPE-choroid samples of AMD patients and dysfunctional RPE cells, and it was consistently upregulated along with RPE differentiation. In vitro study indicated that reduced endogenous LINC00167 expression resulted in RPE dedifferentiation, which was typified by attenuated expression of RPE markers, reduced vascular endothelial growth factor A secretion, accumulation of mitochondrial reactive oxygen species, and interrupted phagocytic ability. Mechanistically, LINC00167 functioned as a sponge for microRNA miR-203a-3p to restore the expression of the suppressor of cytokine signaling 3 (SOCS3), which further inhibited the Janus kinase (JAK)/signal transducer and activator of transcription (STAT) signaling pathway. Taken together, our study demonstrated that LINC00167 showed a protective role in AMD by maintaining RPE differentiation through the LINC00167/miR-203a-3p/SOCS3 axis and might be a potential therapeutic target for AMD.

Circular Noncoding RNA NR3C1 Acts as a miR-382-5p Sponge to Protect RPE Functions via Regulating PTEN/AKT/mTOR Signaling Pathway

Age-related macular degeneration (AMD) is a universal leading cause for irreversible blindness in the elderly population. Dedifferentiation of retinal pigment epithelium (RPE) cells initiates early pathological events in atrophic AMD. Herein, we aim to investigate effects of a circular RNA derived from the NR3C1 gene (circNR3C1) on regulating RPE function and AMD pathogenesis. circNR3C1 expression was consistently upregulated along with RPE differentiation and was downregulated in dysfunctional RPE and blood serum of AMD patients. Silencing of circNR3C1 reduced RPE characteristic transcripts and proteins, interrupted phagocytosis, accelerated intracellular reactive oxygen species (ROS) generation, and promoted RPE proliferation in vitro. circN3C1 silencing also decreased expressions of RPE characteristic markers and disturbed the ultrastructure of RPE in vivo, as shown by a thickened RPE with twisted basal infoldings and outer segments. Mechanistically, circNR3C1 acted as an endogenous microRNA-382-5p (miR-382-5p) sponge to sequester its activity, which increased phosphatase and tensin homolog on chromosome 10 (PTEN) expression and inhibited the protein kinase B/mammalian target of rapamycin (AKT/mTOR) pathway. miR-382-5p overexpression and PTEN silencing mimicked effects of circNR3C1 silencing on RPE phenotypes in vivo and in vitro. In conclusion, circNR3C1 prevents AMD progression and protects RPE by directly sponging miR-382-5p to block its interaction with PTEN and subsequently blocks the AKT/mTOR pathway. Pharmacological circNR3C1 supplementations are promising therapeutic options for atrophic AMD.

Cardiac Extracellular Vesicles (EVs) Released in the Presence or Absence of Inflammatory Cues Support Angiogenesis in Different Manners

Cells release extracellular vesicles (EVs) to communicate in a paracrine manner with other cells, and thereby influence processes, such as angiogenesis. The conditioned medium of human cardiac-derived adherent proliferating (CardAP) cells was recently shown to enhance angiogenesis. To elucidate whether their released EVs are involved, we isolated them by differential centrifugation from the conditioned medium derived either in the presence or absence of a pro-inflammatory cytokine cocktail. Murine recipient cells internalized CardAP-EVs as determined by an intracellular detection of human proteins, such as CD63, by a novel flow cytometry method for studying EV–cell interaction. Moreover, endothelial cells treated for 24 h with either unstimulated or cytokine stimulated CardAP-EVs exhibited a higher tube formation capability on Matrigel. Interestingly, unstimulated CardAP-EVs caused endothelial cells to release significantly more vascular endothelial growth factor and interleukin (IL)-6, while cytokine stimulated CardAP-EVs significantly enhanced the release of IL-6 and IL-8. By nCounter^® miRNA expression assay (NanoString Technologies) we identified microRNA 302d-3p to be enhanced in unstimulated CardAP-EVs compared to their cytokine stimulated counterparts, which was verified by quantitative polymerase chain reaction. This study demonstrates that both CardAP-EVs are pro-angiogenic by inducing different factors from endothelial cells. This would allow to select potent targets for a safe and efficient therapeutic application.

Interaction Of c-Jun And HOTAIR- Increased Expression Of p21 Converge In Polyphyllin I-Inhibited Growth Of Human Lung Cancer Cells

Background

Lung cancer is a leading cause of cancer-related death worldwide. Previously we demonstrated that polyphyllin I (PPI), a bioactive component extracted from Paris polyphylla, inhibited the growth of non-small cell lung cancer (NSCLC) cells through the SAPK/JNK-mediated suppressing p65, DNMT1 and EZH2 expressions. However, the molecular mechanism underlying anti-lung cancer effect by PPI still remain elusive.

Purpose

In this current study, we further explored the molecular mechanism underlying the anti-lung cancer effect of PPI.

Methods

MTT, Cell-Light^TM EdU DNA cell proliferation and colony formation assays were used to measure cell growth. Western blot were used to examine protein levels of c-Jun and p21. The expression level of long non-codingth RNA HOX transcript antisense RNA (HOTAIR) was measured by qRT-PCR. The p21 promoter activity was measured by Dual-Luciferase Reporter Assay System. The transient transfection experiments were used to silence and overexpression of c-Jun, p21 and HOTAIR. Tumor xenograft and bioluminescent imaging experiments were carried out to confirm the in vitro findings.

Results

 We showed that PPI suppressed growth of NSCLC cells. Mechanistically, we observed that PPI reduced expression of HOTAIR, while increased transcription factor c-Jun protein levels. Additionally, PPI also induced protein expression and promoter activity of p21, a cyclin-dependent kinase inhibitor. While exogenously expressed HOTAIR showed no effect on c-Jun levels, silencing of c-Jun significantly reversed the PPI-inhibited HOTAIR expression. Moreover, excessive expressed c-Jun further enhanced PPI-inhibited HOTAIR expression and PPI-induced p21 protein levels. Intriguingly, overexpression of HOTAIR and silencing of c-Jun overcame the PPI-induced p21 protein and promoter activity. Finally, silencing of p21 neutralized the PPI-inhibited cell proliferation. Similar results were also found in one xenograft mouse model.

Conclusion

 Our results demonstrate that PPI inhibits growth of NSCLC cells through regulation of HOTAIR and c-Jun expressions, which lead to induction of p21 gene. The interactions among HOTAIR, c-Jun and p21 regulatory axis converge in the overall anti-lung cancer effect of PPI. This study unveils an additional new mechanism for the anti-lung cancer role of PPI.