Roles of miR-204 in retinal development and maintenance

Update in the molecular mechanism and biomarkers of diabetic retinopathy

Diabetic retinopathy (DR) is a serious complication of diabetes caused by long-term hyperglycemia that leads to microvascular and neuronal damage in the retina. The molecular mechanisms of DR involve oxidative stress, inflammatory responses, neurodegenerative changes, and vascular dysfunction triggered by hyperglycemia. Oxidative stress activates multiple metabolic pathways, such as the polyol, hexosamine, and protein kinase C (PKC) pathways, resulting in the production of, which in turn promote the formation of advanced glycation end products (AGEs). These pathways exacerbate vascular endothelial damage and the release of inflammatory factors, activating inflammatory signaling pathways such as the NF-κB pathway, leading to retinal cell damage and apoptosis. Additionally, DR involves neurodegenerative changes, including the activation of glial cells, neuronal dysfunction, and cell death. Research on the multiomics molecular markers of DR has revealed complex mechanisms at the genetic, epigenetic, and transcriptional levels. Genome-wide association studies (GWASs) have identified multiple genetic loci associated with DR that are involved in metabolic and inflammatory pathways. Noncoding RNAs, such as miRNAs, circRNAs, and lncRNAs, participate in the development of DR by regulating gene expression. Proteomic, metabolomic and lipidomic analyses have revealed specific proteins, metabolites and lipid changes associated with DR, providing potential biomarkers for the early diagnosis and treatment of this disease. This review provides a comprehensive perspective for understanding the molecular network of DR and facilitates the exploration of innovative therapeutic approaches.

Mechanistic and therapeutic perspectives of non-coding RNA-modulated apoptotic signaling in diabetic retinopathy

Diabetic retinopathy (DR), a significant and vision-endangering complication associated with diabetes mellitus, constitutes a substantial portion of acquired instances of preventable blindness. The progression of DR appears to prominently feature the loss of retinal cells, encompassing neural retinal cells, pericytes, and endothelial cells. Therefore, mitigating the apoptosis of retinal cells in DR could potentially enhance the therapeutic approach for managing the condition by suppressing retinal vascular leakage. Recent advancements have highlighted the crucial regulatory roles played by non-coding RNAs (ncRNAs) in diverse biological processes. Recent advancements have highlighted that non-coding RNAs (ncRNAs), including microRNAs (miRNAs), circular RNAs (circRNAs), and long non-coding RNAs (lncRNAs), act as central regulators in a wide array of biogenesis and biological functions, exerting control over gene expression associated with histogenesis and cellular differentiation within ocular tissues. Abnormal expression and activity of ncRNAs has been linked to the regulation of diverse cellular functions such as apoptosis, and proliferation. This implies a potential involvement of ncRNAs in the development of DR. Notably, ncRNAs and apoptosis exhibit reciprocal regulatory interactions, jointly influencing the destiny of retinal cells. Consequently, a thorough investigation into the complex relationship between apoptosis and ncRNAs is crucial for developing effective therapeutic and preventative strategies for DR. This review provides a fundamental comprehension of the apoptotic signaling pathways associated with DR. It then delves into the mutual relationship between apoptosis and ncRNAs in the context of DR pathogenesis. This study advances our understanding of the pathophysiology of DR and paves the way for the development of novel therapeutic strategies.

Retinitis pigmentosa with iris coloboma due to miR-204 gene variant in a Chinese family

PURPOSE

To characterize the phenotype and genotype of a Chinese family with autosomal-dominant retinitis pigmentosa (RP) accompanied by iris coloboma.

METHODS

The proband, a 34-year-old male, was examined with his family by using fundus photography, optical coherence tomography (OCT), autofluorescence, and full-field electroretinography (ffERG). Genetic analyses were conducted through whole-exome sequencing (WES) to screen for variations.

RESULTS

Three members of this Chinese family were shown to be bilateral iris coloboma. The male proband and his mother exhibited typical RP feature. The proband's late grandfather had been documented manifestation of iris coloboma. The mode of inheritance was confirmed to be autosomal dominance. Through linkage analysis and WES, a heterozygous variation in the miR-204 gene (n.37C>T), a noncoding RNA gene, was identified in these three members.

CONCLUSIONS

In this third independent and the first Asian family, the existence of a miR-204 variant associated with RP accompanied by iris coloboma was confirmed. Our findings reinforce the significance of miR-204 as an important factor influencing visual function in the retina. When phenotypes like RP accompanied by iris coloboma in an autosomal-dominant pattern, including in Chinese patients, miR-204 aberrations should be considered.

miR-204 suppresses cancer stemness and enhances osimertinib sensitivity in non-small cell lung cancer by targeting CD44

Osimertinib is an effective treatment option for patients with advanced non-small cell lung cancer (NSCLC) with EGFR activation or T790M resistance mutations; however, acquired resistance to osimertinib can still develop. This study explored novel miRNA-mRNA regulatory mechanisms that contribute to osimertinib resistance in lung cancer. We found that miR-204 expression in osimertinib-resistant lung cancer cells was markedly reduced compared to that in osimertinib-sensitive parental cells. miR-204 expression levels in cancer cells isolated from treatment-naive pleural effusions were significantly higher than those in cells with acquired resistance to osimertinib. miR-204 enhanced the sensitivity of lung cancer cells to osimertinib and suppressed spheroid formation, migration, and invasion of lung cancer cells. Increased miR-204 expression in osimertinib-resistant cells reversed resistance to osimertinib and enhanced osimertinib-induced apoptosis by upregulating BIM expression levels and activating caspases. Restoration of CD44 (the direct downstream target gene of miR-204) expression reversed the effects of miR-204 on osimertinib sensitivity, recovered cancer stem cell and mesenchymal markers, and suppressed E-cadherin expression. The study demonstrates that miR-204 reduced cancer stemness and epithelial-to-mesenchymal transition, thus overcoming osimertinib resistance in lung cancer by inhibiting the CD44 signaling pathway.

Molecular mechanism underlying miR-204-5p regulation of adipose-derived stem cells differentiation into cells from three germ layers

The limited differentiation ability of adipose-derived stem cells (ADSCs) limits their application in stem cell therapy and regenerative medicine. Here, we explore the molecular mechanism by which miR-204-5p regulates ADSCs differentiation into cells derived from the three germ layers (i.e., adipocytes, neurocytes, and hepatocytes). Although miR-204-5p overexpression inhibited ADSCs differentiation into adipocytes, neurocyte and hepatocyte differentiation were promoted. Mechanistically, miR-204-5p inhibited the expression of PPARG by regulating the AMPK signaling pathway, thereby inhibiting ADSCs differentiation into adipocytes. Further, miR-204-5p regulated JAG1/NOTCH3 axis for the inhibition of differentiation into adipocytes and promotion of differentiation into neurocytes. miR-204-5p might also promote ADSCs differentiation into hepatocytes by upregulating E2F8. The findings of this study provide novel insights into the regulatory mechanisms underlying early embryonic development and will help to facilitate the application of ADSCs in stem cell therapy and regenerative medicine.

Advances in Research Related to MicroRNA for Diabetic Retinopathy

Diabetic retinopathy (DR) is a severe microvascular complication of diabetes and is one of the primary causes of blindness in the working-age population in Europe and the United States. At present, no cure is available for DR, but early detection and timely intervention can prevent the rapid progression of the disease. Several treatments for DR are known, primarily ophthalmic treatment based on glycemia, blood pressure, and lipid control, which includes laser photocoagulation, glucocorticoids, vitrectomy, and antivascular endothelial growth factor (anti-VEGF) medications. Despite the clinical efficacy of the aforementioned therapies, none of them can entirely shorten the clinical course of DR or reverse retinopathy. MicroRNAs (miRNAs) are vital regulators of gene expression and participate in cell growth, differentiation, development, and apoptosis. MicroRNAs have been shown to play a significant role in DR, particularly in the molecular mechanisms of inflammation, oxidative stress, and neurodegeneration. The aim of this review is to systematically summarize the signaling pathways and molecular mechanisms of miRNAs involved in the occurrence and development of DR, mainly from the pathogenesis of oxidative stress, inflammation, and neovascularization. Meanwhile, this article also discusses the research progress and application of miRNA-specific therapies for DR.

Shared Molecular Pathways in Glaucoma and Other Neurodegenerative Diseases: Insights from RNA-Seq Analysis and miRNA Regulation for Promising Therapeutic Avenues

Advances in RNA-sequencing technologies have led to the identification of molecular biomarkers for several diseases, including neurodegenerative diseases, such as Alzheimer's, Parkinson's, Huntington's diseases and Amyotrophic Lateral Sclerosis. Despite the nature of glaucoma as a neurodegenerative disorder with several similarities with the other above-mentioned diseases, transcriptional data about this disease are still scarce. microRNAs are small molecules (~17-25 nucleotides) that have been found to be specifically expressed in the CNS as major components of the system regulating the development signatures of neurodegenerative diseases and the homeostasis of the brain. In this review, we sought to identify similarities between the functional mechanisms and the activated pathways of the most common neurodegenerative diseases, as well as to discuss how those mechanisms are regulated by miRNAs, using RNA-Seq as an approach to compare them. We also discuss therapeutically suitable applications for these disease hallmarks in clinical future studies.

Unraveling the Roles of miR-204-5p and HMGA2 in Papillary Thyroid Cancer Tumorigenesis

Thyroid cancer is the most common endocrine malignant tumor with an increasing incidence rate. Although differentiated types of thyroid cancer generally present good clinical outcomes, some dedifferentiate into aggressive and lethal forms. However, the molecular mechanisms governing aggressiveness and dedifferentiation are still poorly understood. Aberrant expression of miRNAs is often correlated to tumor development, and miR-204-5p has previously been identified in papillary thyroid carcinoma as downregulated and associated with aggressiveness. This study aimed to explore its role in thyroid tumorigenesis. To address this, gain-of-function experiments were performed by transiently transfecting miR-204-5p in thyroid cancer cell lines. Then, the clinical relevance of our data was evaluated in vivo. We prove that this miRNA inhibits cell invasion by regulating several targets associated with an epithelial-mesenchymal transition, such as SNAI2, TGFBR2, SOX4 and HMGA2. HMGA2 expression is regulated by the MAPK pathway but not by the PI3K, IGF1R or TGFβ pathways, and the inhibition of cell invasion by miR-204-5p involves direct binding and repression of HMGA2. Finally, we confirmed in vivo the relationship between miR-204-5p and HMGA2 in human PTC and a corresponding mouse model. Our data suggest that HMGA2 inhibition offers promising perspectives for thyroid cancer treatment.

MicroRNAs in the Mouse Developing Retina

The retina is among the highest organized tissues of the central nervous system. To achieve such organization, a finely tuned regulation of developmental processes is required to form the retinal layers that contain the specialized neurons and supporting glial cells to allow precise phototransduction. MicroRNAs are a class of small RNAs with undoubtful roles in fundamental biological processes, including neurodevelopment of the brain and the retina. This review provides a short overview of the most important findings regarding microRNAs in the regulation of retinal development, from the developmental-dependent rearrangement of the microRNA expression program to the key roles of particular microRNAs in the differentiation and maintenance of retinal cell subtypes.

Exosomal MicroRNA Profiling in Vitreous Humor Derived From Pathological Myopia Patients

Purpose

Pathologic myopia (PM) is one of the primary causes of blindness. This study aims to explore the possible relations between the composition of microRNA in vitreous exosomes of patients with PM and the progression of myopic maculopathy.

Methods

Vitreous humor (VH) samples were collected from patients undergoing retinal surgery. A total of 15 and 12 VH samples were obtained from patients with PM and control, respectively. The PM group was divided into PM-L (G2) and PM-H groups (G3 and G4) in order to explore differentially expressed microRNAs (DEMs) that account for the relatively poor prognosis in G3 and G4 myopic maculopathy. A Weighted Gene Co-Expression Network Analysis (WGCNA) was conducted to find the persistently altered key microRNAs in myopic maculopathy progression. The Gene Ontology (GO) enrichment analysis and Kyoto Encyclopedia of Genes and Genome (KEGG) pathway enrichment analysis were used.

Results

High purity exosomes were extracted from the vitreous fluid of patients with PM and control. The top five downregulated DEMs of PM-H versus PM-L can reflect the tendency of deterioration of PM-H myopic maculopathy. MiR-143-3p and miR-145-5p, which were found in WGCNA, may participate in the development of myopic maculopathy. These microRNAs all relate to the insulin resistance pathway.

Conclusions

This is the first study to explore the relations between the progression of myopic maculopathy and vitreous exosomal microRNAs. Vitreous exosomal miR-143-3p and miR-145-5p can be considered biomarkers for patients with PM, and the vitreous exosomal DEM associated with PM-H may represent alarming signals of myopic maculopathy deterioration.

Induced pluripotent stem cells: Generation methods and a new perspective in COVID-19 research

Induced pluripotent stem cells (iPSCs) exhibit an unlimited ability to self-renew and produce various differentiated cell types, thereby creating high hopes for both scientists and patients as a great tool for basic research as well as for regenerative medicine purposes. The availability and safety of iPSCs for therapeutic purposes require safe and highly efficient methods for production of these cells. Different methods have been used to produce iPSCs, each of which has advantages and disadvantages. Studying these methods would be very helpful in developing an easy, safe, and efficient method for the generation of iPSCs. Since iPSCs can be generated from somatic cells, they can be considered as valuable cellular resources available for important research needs and various therapeutic purposes. Coronavirus disease 2019 (COVID-19) is a disease that has endangered numerous human lives worldwide and currently has no definitive cure. Therefore, researchers have been rigorously studying and examining all aspects of COVID-19 and potential treatment modalities and various drugs in order to enable the treatment, control, and prevention of COVID-19. iPSCs have become one of the most attractive and promising tools in this field by providing the ability to study COVID-19 and the effectiveness of drugs on this disease outside the human body. In this study, we discuss the different methods of generation of iPSCs as well as their respective advantages and disadvantages. We also present recent applications of iPSCs in the study and treatment of COVID-19.

miR-204-5p Inhibits the Proliferation and Differentiation of Fetal Neural Stem Cells by Targeting Wingless-Related MMTV Integration Site 2 to Regulate the Ephrin-A2/EphA7 Pathway

Neonatal hypoxic ischemic encephalopathy (HIE) is mainly resulted from perinatal asphyxia, which can be repaired by NSCs. miR-204-5p is claimed to impact the activity NSCs. Our research will probe the miR-204-5p function in oxygen-glucose deprivation (OGD)-treated NSCs. miR-204-5p level was enhanced and WNT2 level was reduced in HIE rats. Rat NSCs were stimulated with OGD condition under the managing of mimic or inhibitor of miR-204-5p. The declined cell viability, enhanced apoptosis, downregulated Tuj1 and GFAP levels, and shortened total neurite length were observed in OGD-treated NSCs, which were further aggravated by the mimic and rescued by the inhibitor of miR-204-5p. Furthermore, the inactivated WNT2 and Ephrin-A2/EphA7 signaling pathway in OGD-stimulated NSCs was further repressed by the mimic and rescued by the inhibitor of miR-204-5p. In addition, WNT2 was confirmed as the targeting of miR-204-5p. Lastly, the function of miR-204-5p mimic on the proliferation, apoptosis, differentiation, WNT2 and Ephrin-A2/EphA7 signaling pathway in OGD-stimulated NSCs was abolished by HLY78, an activator of Wnt signaling. Collectively, miR-204-5p repressed the growth and differentiation of fetal NSCs by targeting WNT2 to regulate the Ephrin-A2/EphA7 pathway.

The role of the mTOR pathway in diabetic retinopathy

The retina, the part of the eye, translates the light signal into an electric current that can be sent to the brain as visual information. To achieve this, the retina requires fine-tuned vascularization for its energy supply. Diabetic retinopathy (DR) causes alterations in the eye vascularization that reduce the oxygen supply with consequent retinal neurodegeneration. During DR, the mammalian target of rapamycin (mTOR) pathway seems to coordinate retinal neurodegeneration with multiple anabolic and catabolic processes, such as autophagy, oxidative stress, cell death, and the release of pro-inflammatory cytokines, which are closely related to chronic hyperglycemia. This review outlines the normal anatomy of the retina and how hyperglycemia can be involved in the neurodegeneration underlying this disease through over activation or inhibition of the mTOR pathway.

circKMT2E Protect Retina from Early Diabetic Retinopathy through SIRT1 Signaling Pathway via Sponging miR-204-5p

Objective

To explore the changes of circRNAs in the retina of diabetic patients without diabetic retinopathy (DR) to screen latent protective factor.

Methods

The sequencing data of the retina from three diabetic donors that possess no noticeable pathological feature of the retina at ultimate eye inspection and three healthy donative samples were involved in this study. Herein, we carried out bioinformatics analysis to disclose the expression pattern and characteristics of circRNAs on the basis of Gene Ontology as well as KEGG pathway analyses. Then, sequencing data were applied to infer the interaction between selected circRNAs and miR-204-5p. The potential miRNA response elements for the annotated circRNAs and their target gene were speculated using TargetScan as well as miRanda.

Results

RNA sequencing detected 28,978 alternative circRNAs. Thereinto, 1063 were expressed with significant difference. circKMT2E was upregulated more than two folds in alloxan-induced diabetic retinal tissues compared with normal retinal tissues, exhibiting an expression trend opposite to miR-204-5p. Bioinformatics analysis showed that circKMT2E have four seed sequences on hsa-miR-204-5p. Thus, circKMT2E was speculated to have function on the basis of sponging miR-204-5p in order to participate in the pathogenetic process of DR. Besides, miR-204-5p was speculated to be able to bind SIRT1, which can interact with its target proteins, and adjusts various cell functions including cellular inflammatory responses, proliferation, as well as apoptosis.

Conclusion

The upregulation of circKMT2E in the early stage of DR may be involved in its pathogenesis and may activate the SIRT1 signaling pathway to protect the retina by the sponge function to miR-204-5p.

Investigation of Key Signaling Pathways Associating miR-204 and Common Retinopathies

MicroRNAs are a large group of small noncoding RNAs that work in multiple cellular pathways. miR-204, as one of the key axes in the development, maintenance, and pathogenesis of the retina, plays several roles by modulating its target genes. This study was aimed at evaluating the target genes of miR-204 involved in the development and progression of common retinopathies such as glaucoma, retinoblastoma, and age-related macular degeneration. In this study, three datasets related to retinopathies (GSE50195, GSE27276, and GSE97508) were selected from Gene Expression Omnibus. miR-204 target genes were isolated from TargeScan. The shares between retinopathy and miR-204 target genes were then categorized. Using Enrichr and STRING, we highlighted the signaling pathways and the relationships between the proteins. SHC1 events in ERBB2, adherent junction's interactions, NGF signaling via TRKA from the plasma membrane, IRF3-mediated activation of type 1 IFN, pathways in upregulated genes and G0 and early G1, RORA-activated gene expression, PERK-regulated gene expression, adherent junction's interactions, and CREB phosphorylation pathways in downregulated genes were identified in glaucoma, retinoblastoma, and age-related macular degeneration. WEE1, SMC2, HMGB1, RRM2, and POLA1 proteins were also observed to be involved in the progression and invasion of retinoblastoma; SLC24A2 and DTX4 in age-related macular degeneration; and EPHB6, EFNB3, and SHC1 in glaucoma. Continuous bioinformatics analysis has shown that miR-204 has a significant presence and expression in retinal tissue, and approximately 293 genes are controlled and regulated by miR-204 in this tissue; also, target genes of miR-204 have the potential to develop various retinopathies; thus, a study of related target genes can provide appropriate treatment strategies in the future.

Study on Serum miR-204 Expression Levels in Patients with Severe Pneumonia and Patients with Primary Bronchial Lung Cancer and Its Diagnostic Value

Objective. To analyze the expression and clinical significance of miR-204 in the serum of patients with severe pneumonia (SP) and primary bronchial lung cancer (LC). Methods. 65 SP patients and 43 primary bronchial LC patients who were treated in the hospital from January 2017 to December 2018 were randomly selected as the SP group and LC group. At the same time, healthy patients from the physical examination department of the hospital were selected. 65 cases were the control group. QRT-PCR detected serum miR-204 expression and compared the differences between groups. The pathological data of patients were collected, and the relationship between serum miR-204 and the patient’s pathological data was compared; the area under the ROC curve and Kaplan–Meier curve were used to evaluate the diagnostic value of serum miR-204 for the two conditions and to explore the relationship between serum miR-204 and prognosis. Results. The serum miR-204 of the SP group was (0.43 ± 0.09), the serum miR-204 of the LC group was (0.40 ± 0.10), the serum miR-204 of the control group was (1.00 ± 0.09), and the miR-204 level of was significantly higher than that of the control group, and the difference between the groups was statistically significant ( $P$  < 0.05). There was no significant difference in serum miR-204 levels between the SP group and the LC group ( $P$  > 0.05). Serum miR-204 levels in SP patients with cumulative organs ≥3 were higher than those with cumulative organs <3, and the difference was statistically significant ( $P$  < 0.001). In the LC group, in patients with stage III to IV and low and undifferentiated patients, the level of miR-204 was higher than that of stage I∼II and high and moderately differentiated patients, and the difference was statistically significant ( $P$  < 0.001). The level of miR-204 in the two groups of patients (0.89 ± 0.10, 0.83 ± 0.13) who died of illness was significantly higher than that of the surviving patients (1.00 ± 0.11, 1.00 ± 0.10), and the difference was statistically significant ( $P$  < 0.05); the survival rate of patients with high expression of miR-204 was higher than that of patients with low expression. The AUC of serum miR-204 level to SP and LC was 0.766 and 0.818, respectively. Conclusion. The level of miR-204 in the serum of SP patients and patients with primary bronchial LC was significantly lower than that of healthy people, and patients who died were lower than those who survived; the miR-204 in serum has a good diagnostic value for SP and LC and is related to the survival and prognosis of patients.