MicroRNA regulation of critical retinal pigment epithelial functions

hsa_circ_0087100/hsa-miR-6743-5p affects Th1 cell differentiation by regulating STAT1 in diabetic retinopathy

Objective: To elucidate the role of the competitive endogenous RNA (ceRNA) network in immune infiltration of diabetic retinopathy (DR). Methods: We obtained differentially expressed (DE) circRNAs, miRNAs and mRNAs from the Gene Expression Omnibus database. Then, we identified immune infiltration by CIBERSORT and single-sample gene set enrichment analysis and discovered co-expression genes by weighted gene co-expression network analysis. Furthermore, STAT1-mediated Th1 differentiation was determined in DR cell models, DR patients and DR mouse models. Results: hsa_circ_0087100/hsa-miR-6743-5p/STAT1 was involved in immune infiltration of Th1 cells. Aberrant expression of the ceRNA network and STAT1-mediated Th1 differentiation was thus verified in vitro and in vivo. Conclusion: hsa_circ_0087100/hsa-miR-6743-5p/STAT1 may affect Th1 cell differentiation in DR.

Hyperglycemia-induced miR182-5p drives glycolytic and angiogenic response in Proliferative Diabetic Retinopathy and RPE cells via depleting FoxO1

PURPOSE

Diabetic Retinopathy (DR) is associated with metabolic dysfunction in cells such as retinal pigmented epithelium (RPE). Small molecular weight microRNAs can simultaneously regulate multiple gene products thus having pivotal roles in disease pathogenesis. Since miR182-5p is involved in regulating glycolysis and angiogenesis, two pathologic processes of DR, we investigated its status in DR eyes and in high glucose model in vitro.

METHOD

ology: Total RNA was extracted from vitreous humor of PDR (n = 48) and macular hole (n = 22) subjects followed by quantification of miR182-5p and its target genes. ARPE-19 cells, cultured in DMEM under differential glucose conditions (5 mM and 25 mM) were used for metabolic and biochemical assays. Cells were transfected with miRNA182 mimic or antagomir to evaluate the gain and loss of function effects.

RESULTS

PDR patient eyes had high levels of miR182-5p levels (p < 0.05). RPE cells under high glucose stress elevated miR182-5p expression with altered glycolytic pathway drivers such as HK2, PFKP and PKM2 over extended durations. Additionally, RPE cells under high glucose conditions exhibited reduced FoxO1 and enhanced Akt activation. RPE cells transfected with miR182-5p mimic phenocopied the enhanced basal and compensatory glycolytic rates observed under high glucose conditions with increased VEGF secretion. Conversely, inhibiting miR182-5p reduced Akt activation, glycolytic pathway proteins, and VEGF while stabilizing FoxO1.

CONCLUSION

Glycolysis-associated proteins downstream of the FoxO1-Akt axis were regulated by miR182-5p. Further, miR182-5p increased expression of VEGFR2 and VEGF levels, likely via inhibition of ZNF24. Thus, the FoxO1-Akt-glycolysis/VEGF pathway driving metabolic dysfunction with concurrent angiogenic signaling in PDR may be potentially targeted for treatment via miR182-5p modulation.

Long Noncoding RNA MIAT Modulates Chronic Retinal Ischemia-Reperfusion Injury in Mice via the microRNA-203-3p/SNAI2 Axis

Retinal ischemia-reperfusion injury (RIRI) is a vital pathological process of multiple ocular diseases. This study aimed at investigating the effects of the MIAT/miR-203-3p/SNAI2 axis on RIRI. RIRI was produced by inducing an exceedingly high intraocular pressure (IOP) in mice. Mouse retinal ganglion cells (RGCs) were subjected to oxygen-glucose deprivation/reoxygenation (OGD/R) to mimic in vitro models. Relevant oligonucleotides or plasmids were transfected into OGD/R-induced RGCs in vitro or injected into RIRI mice models in vivo via a vitreous cavity. The findings of our paper indicated that MIAT and SNAI2 were highly expressed and miR-203-3p was lowly expressed in mouse RIRI tissues and OGD/R-induced RGCs. Interfering MIAT promoted the viability of OGD/R-induced RGCs, decreased apoptosis, and reduced oxidative stress in vitro. Silencing MIAT increased retinal neuronal cell numbers and decreased retinal neuronal cell apoptosis in mouse RIRI tissues in vivo. MIAT sponged miR-203-3p, and miR-203-3p targeted and inhibited SNAI2 expression. SNAI2 up-regulation or miR-203-3p down-regulation reversed the protective effects of MIAT down-regulation on RIRI in mice and OGD/R-induced RGCs. MIAT sponges miR-203-3p upregulated the expression of SNAI2, thereby promoting RIRI in mice. In summary, MIAT may be a therapeutic target for the treatment of chronic RIRI.

ERp29 Attenuates Nicotine-Induced Endoplasmic Reticulum Stress and Inhibits Choroidal Neovascularization

Nicotine-induced endoplasmic reticulum (ER) stress in retinal pigment epithelium (RPE) cells is thought to be one pathological mechanism underlying age-related macular degeneration (AMD). ERp29 attenuates tobacco extract-induced ER stress and mitigates tight junction damage in RPE cells. Herein, we aimed to further investigate the role of ERp29 in nicotine-induced ER stress and choroidal neovascularization (CNV). We found that the expression of ERp29 and GRP78 in ARPE-19 cells was increased in response to nicotine exposure. Overexpression of ERp29 decreased the levels of GRP78 and the C/EBP homologous protein (CHOP). Knockdown of ERp29 increased the levels of GRP78 and CHOP while reducing the viability of ARPE-19 cells under nicotine exposure conditions. In the ARPE-19 cell/macrophage coculture system, overexpression of ERp29 decreased the levels of M2 markers and increased the levels of M1 markers. The viability, migration and tube formation of human umbilical vein endothelial cells (HUVECs) were inhibited by conditioned medium from the ERp29-overexpressing group. Moreover, overexpression of ERp29 inhibits the activity and growth of CNV in mice exposed to nicotine in vivo. Taken together, our results revealed that ERp29 attenuated nicotine-induced ER stress, regulated macrophage polarization and inhibited CNV.

Recent advances of exosomes in age-related macular degeneration

Exosomes are 30-150 nm extracellular vesicles that are secreted by almost all types of cells. Exosomes contain a variety of biologically active substances, such as proteins, nucleic acids, and lipids, and are important in the intercellular communication of biological mediators involved in nerve injury and repair, vascular regeneration, immune response, fibrosis formation, and many other pathophysiological processes. Although it has been extensively studied in the field of cancer, the exploration of ocular diseases has only just begun. Here, we discuss the latest developments in exosomes for age-related macular degeneration (AMD), including the pathogenesis of exosomes in age-related macular degeneration, their potential as diagnostic markers, and therapeutic vectors of the disease. Finally, the study of exosomes in age-related macular degeneration is still relatively few, and more detailed basic research and clinical trials are needed to verify its application in treatment and diagnosis, so as to adopt more personalized diagnosis and treatment strategies to stop the progression of age-related macular degeneration.

O-GlcNAcylation regulates phagocytosis by promoting Ezrin localization at the cell cortex

O-GlcNAcylation is a post-translational modification that serves as a cellular nutrient sensor and participates in multiple physiological and pathological processes. However, it remains uncertain whether O-GlcNAcylation is involved in the regulation of phagocytosis. Here, we demonstrate a rapid increase in protein O-GlcNAcylation in response to phagocytotic stimuli. Knockout of O-GlcNAc transferase or pharmacological inhibition of O-GlcNAcylation dramatically blocks phagocytosis, resulting in the disruption of retinal structure and function. Mechanistic studies reveal that O-GlcNAc transferase interacts with Ezrin, a membrane-cytoskeleton linker protein, to catalyze its O-GlcNAcylation. Our data further show that Ezrin O-GlcNAcylation promotes its localization to the cell cortex, thereby stimulating the membrane-cytoskeleton interaction needed for efficient phagocytosis. These findings identify a previously unrecognized role for protein O-GlcNAcylation in phagocytosis with important implications in both health and diseases.

Autophagy in age-related macular degeneration

Age-related macular degeneration (AMD) is the leading cause of visual impairment in the aging population with limited understanding of its pathogenesis and a lack of effective treatment. The progression of AMD is initially characterized by atrophic alterations in the retinal pigment epithelium, as well as the formation of lysosomal lipofuscin and extracellular drusen deposits. Damage caused by chronic oxidative stress, protein aggregation and inflammatory processes may lead to geographic atrophy and/or choroidal neovascularization and fibrosis. The role of macroautophagy/autophagy in AMD pathology is steadily emerging. This review describes selective and secretory autophagy and their role in drusen biogenesis, senescence-associated secretory phenotype, inflammation and epithelial-mesenchymal transition in the pathogenesis of AMD.Abbreviations: Aβ: amyloid-beta; AMBRA1: autophagy and beclin 1 regulator 1; AMD: age-related macular degeneration; ATF6: activating transcription factor 6; ATG: autophagy related; BACE1: beta-secretase 1; BHLHE40: basic helix-loop-helix family member e40; BNIP3: BCL2 interacting protein 3; BNIP3L/NIX: BCL2 interacting protein 3 like; C: complement; CALCOCO2/NDP52: calcium binding and coiled-coil domain 2; CARD: caspase recruitment domain; CDKN2A/p16: cyclin dependent kinase inhibitor 2A; CFB: complement factor B; DELEC1/Dec1; deleted in esophageal cancer 1; EIF2AK3/PERK: eukaryotic translation initiation factor 2 alpha kinase 3; EMT: epithelial-mesenchymal transition; ER: endoplasmic reticulum; ERN1/IRE1: endoplasmic reticulum to nucleus signaling 1; FUNDC1: FUN14 domain containing 1; GABARAP: GABA type A receptor-associated protein; HMGB1: high mobility group box 1; IL: interleukin; KEAP1: kelch like ECH associated protein 1; LAP: LC3-associated phagocytosis; LAMP2: lysosomal associated membrane protein 2; LIR: LC3-interacting region; MAP1LC3/LC3: microtubule associated protein 1 light chain 3; MTOR: mechanistic target of rapamycin kinase; NFE2L2: NFE2 like bZIP transcription factor 2; NLRP3; NLR family pyrin domain containing 3; NFKB/NFκB: nuclear factor kappa B; OPTN: optineurin; PARL: presenilin associated rhomboid like; PGAM5: PGAM family member 5, mitochondrial serine/threonine protein phosphatase; PINK1: PTEN induced kinase 1; POS: photoreceptor outer segment; PPARGC1A: PPARG coactivator 1 alpha; PRKN: parkin RBR E3 ubiquitin protein ligase; PYCARD/ASC: PYD and CARD domain containing; ROS: reactive oxygen species; RPE: retinal pigment epithelium; SA: secretory autophagy; SASP: senescence-associated secretory phenotype; SEC22B: SEC22 homolog B, vesicle trafficking protein; SNAP: synaptosome associated protein; SNARE: soluble N-ethylmaleimide-sensitive factor attachment protein receptor; SQSTM1/p62: sequestosome 1; STX: syntaxin; TGFB2: transforming growth factor beta 2; TRIM16: tripartite motif containing 16; TWIST: twist family bHLH transcription factor; Ub: ubiquitin; ULK: unc-51 like autophagy activating kinase; UPR: unfolded protein response; UPS: ubiquitin-proteasome system; V-ATPase: vacuolar-type H+-translocating ATPase; VIM: vimentin.

Retinal Pigment Epithelium Cell Development: Extrapolating Basic Biology to Stem Cell Research

The retinal pigment epithelium (RPE) forms an important cellular monolayer, which contributes to the normal physiology of the eye. Damage to the RPE leads to the development of degenerative diseases, such as age-related macular degeneration (AMD). Apart from acting as a physical barrier between the retina and choroidal blood vessels, the RPE is crucial in maintaining photoreceptor (PR) and visual functions. Current clinical intervention to treat early stages of AMD includes stem cell-derived RPE transplantation, which is still in its early stages of evolution. Therefore, it becomes essential to derive RPEs which are functional and exhibit features as observed in native human RPE cells. The conventional strategy is to use the knowledge obtained from developmental studies using various animal models and stem cell-based exploratory studies to understand RPE biogenies and developmental trajectory. This article emphasises such studies and aims to present a comprehensive understanding of the basic biology, including the genetics and molecular pathways of RPE development. It encompasses basic developmental biology and stem cell-based developmental studies to uncover RPE differentiation. Knowledge of the in utero developmental cues provides an inclusive methodology required for deriving RPEs using stem cells.

Tissue engineering in growth plate cartilage regeneration: Mechanisms to therapeutic strategies

The repair of growth plate injuries is a highly complex process that involves precise spatiotemporal regulation of multiple cell types. While significant progress has been made in understanding the pathological mechanisms underlying growth plate injuries, effectively regulating this process to regenerate the injured growth plate cartilage remains a challenge. Tissue engineering technology has emerged as a promising therapeutic approach for achieving tissue regeneration through the use of functional biological materials, seed cells and biological factors, and it is now widely applied to the regeneration of bone and cartilage. However, due to the unique structure and function of growth plate cartilage, distinct strategies are required for effective regeneration. Thus, this review provides an overview of current research on the application of tissue engineering to promote growth plate regeneration. It aims to elucidates the underlying mechanisms by which tissue engineering promotes growth plate regeneration and to provide novel insights and therapeutic strategies for future research on the regeneration of growth plate.

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.

The Role of microRNA in the Inflammatory Response of Wound Healing

Wound healing, a highly complex pathophysiological response to injury, includes four overlapping phases of hemostasis, inflammation, proliferation, and remodeling. Initiation and resolution of the inflammatory response are the primary requirements for wound healing, and are also key events that determines wound quality and healing time. Currently, the number of patients with persistent chronic wounds has generally increased, which imposes health and economic burden on patients and society. Recent studies have found that microRNA(miRNA) plays an essential role in the inflammation involved in wound healing and may provide a new therapeutic direction for wound treatment. Therefore, this review focused on the role and significance of miRNA in the inflammation phase of wound healing.

MicroRNAs Are Key Molecules Involved in the Gene Regulation Network of Colorectal Cancer

Colorectal cancer (CRC) is one of the most common types of cancer and one of the leading causes of mortality worldwide. MicroRNAs (miRNAs) play central roles in normal cell maintenance, development, and other physiological processes. Growing evidence has illustrated that dysregulated miRNAs can participate in the initiation, progression, metastasis, and therapeutic resistance that confer miRNAs to serve as clinical biomarkers and therapeutic targets for CRC. Through binding to the 3′-untranslated region (3′-UTR) of target genes, miRNAs can lead to target mRNA degradation or inhibition at a post-transcriptional level. During the last decade, studies have found numerous miRNAs and their potential targets, but the complex network of miRNA/Targets in CRC remains unclear. In this review, we sought to summarize the complicated roles of the miRNA-target regulation network (Wnt, TGF-β, PI3K-AKT, MAPK, and EMT related pathways) in CRC with up-to-date, high-quality published data. In particular, we aimed to discuss the downstream miRNAs of specific pathways. We hope these data can be a potent supplement for the canonical miRNA-target regulation network.

Update of application of olfactory ensheathing cells and stem cells/exosomes in the treatment of retinal disorders

Age-related macular degeneration, diabetic retinopathy, retinitis pigmentosa and other retinal disorders are the main causes of visual impairment worldwide. In the past, these retinal diseases, especially dry age-related macular degeneration, proliferative diabetic retinopathy and retinitis pigmentosa, were treated with traditional surgery and drugs. However, the effect was moderate. In recent years, researchers have used embryonic stem cells, induced pluripotent stem cells, mesenchymal stem cells, olfactory ensheathing cells and other stem cells to conduct experiments and found that stem cells can inhibit inflammation, regulate immune response, secrete neurotrophic factors, and differentiate into retinal cells to replace and promote restoration of the damaged parts. These stem cells have the potential to treat retinal diseases. Whether it is in animal experiments or clinical trials, the increase in the number of retinal cells, maintenance of function and improvement of visual function all reflect the advanced of stem cells to treat retinal diseases, but its risk preserves the donor's hidden pathogenic genes, immune rejection and tumorigenicity. With the development of exosomes study, researchers have discovered that exosomes come from a wide range of sources and can be secreted by almost all types of cells. Using exosomes with stem cell to treat retinal diseases is more effective than using stem cells alone. This review article summarizes the recent advances in the application of olfactory ensheathing cells and stem cells/exosomes in the treatment of retinal disorders.