Circular RNA circZNF292 regulates H2 O2 -induced injury in human lens epithelial HLE-B3 cells depending on the regulation of the miR-222-3p/E2F3 axis

Deciphering the role of circular RNAs in cancer progression under hypoxic conditions

Hypoxia, characterized by reduced oxygen levels, plays a pivotal role in cancer progression, profoundly influencing tumor behavior and therapeutic responses. A hallmark of solid tumors, hypoxia drives significant metabolic adaptations in cancer cells, primarily mediated by hypoxia-inducible factor-1α (HIF-1α), a key transcription factor activated in low-oxygen conditions. This hypoxic environment promotes epithelial-mesenchymal transition (EMT), enhancing cancer cell migration, metastasis, and the development of cancer stem cell-like properties, which contribute to therapy resistance. Moreover, hypoxia modulates the expression of circular RNAs (circRNAs), leading to their accumulation in the tumor microenvironment. These hypoxia-responsive circRNAs regulate gene expression and cellular processes critical for cancer progression, making them promising candidates for diagnostic and prognostic biomarkers in various cancers. This review delves into the intricate interplay between hypoxic circRNAs, microRNAs, and RNA-binding proteins, emphasizing their role as molecular sponges that modulate gene expression and signaling pathways involved in cell proliferation, apoptosis, and metastasis. It also explores the relationship between circRNAs and the tumor microenvironment, particularly how hypoxia influences their expression and functional dynamics. Additionally, the review highlights the potential of circRNAs as diagnostic and prognostic tools, as well as their therapeutic applications in innovative cancer treatments. By consolidating current knowledge, this review underscores the critical role of circRNAs in cancer biology and paves the way for future research aimed at harnessing their unique properties for clinical advancements. Specifically, this review examines the biogenesis, expression patterns, and mechanistic actions of hypoxic circRNAs, focusing on their ability to act as molecular sponges for microRNAs and their interactions with RNA-binding proteins. These interactions impact key signaling pathways related to tumor growth, metastasis, and drug resistance, offering new insights into the complex regulatory networks governed by circRNAs under hypoxic stress.

The Hsa_circ_0105558/miR-182-5p/ATF6 Cascade Affects H2O2-Triggered Oxidative Damage and Apoptosis of Human Lens Epithelial Cells

Age-related cataract (ARC) is the prevalent cause of useful vision loss. Circular RNAs are related to ARC pathogenesis partly through their competing endogenous RNA (ceRNA) activity. Herein, we defined the action of hsa_circ_0105558 in hydrogen peroxide (H2O2)-driven apoptosis and oxidative damage in human lens epithelial SRA01/04 cells. Hsa_circ_0105558, microRNA (miR)-182-5p and activating transcription factor 6 (ATF6) were evaluated by a qRT-PCR or immunoblotting method. The hsa_circ_0105558/miR-182-5p and miR-182-5p/ATF6 relationships were predicted by bioinformatics analysis and confirmed by dual-luciferase reporter assay. Reactive oxygen species level, glutathione peroxidase level, superoxide dismutase activity, and malondialdehyde level were measured using the matched assay kits. Hsa_circ_0105558 was upregulated in human ARC lens and H2O2-exposed SRA01/04 cells. Suppression of hsa_circ_0105558 attenuated H2O2-driven SRA01/04 cell apoptosis and oxidative damage. Hsa_circ_0105558 targeted miR-182-5p, and reduced miR-182-5p expression reversed the influence of hsa_circ_0105558 depletion on H2O2-driven oxidative damage and apoptosis. ATF6 was a target of miR-182-5p, and miR-182-5p-driven downregulation of ATF6 regulated cell oxidative damage and apoptosis under H2O2 insult. Moreover, hsa_circ_0105558 functioned as a ceRNA to post-transcriptionally control ATF6 expression through miR-182-5p competition. Our study demonstrates that hsa_circ_0105558 modulates SRA01/04 cell oxidative damage and apoptosis under H2O2 insult through the miR-182-5p/ATF6 cascade.

The evolution and functional characterization of transcription factors E2Fs in lamprey, Lethenteron reissneri

The E2 promoter binding factors (E2Fs) are a group of transcriptional regulators that govern the cell cycle and play crucial roles in various cellular physiological processes, including proliferation and embryonic development. In this study, we identified four homologous genes-Lr-E2F3, Lr-E2F4, Lr-E2F5, and Lr-E2F8-from the lamprey (Lethenteron reissneri) genome database. Phylogenetic tree analysis was conducted to elucidate the evolutionary relationships within the E2F family across different species. Furthermore, analyses of motifs, domains, gene structures, and 3D structures reinforced the conservation of the E2F family. Notably, synteny analysis revealed that the neighboring genes of the Lr-E2Fs exhibited greater diversity compared to those in jawed vertebrates. Activity assays indicated that Lr-E2Fs may be involved in lamprey innate immunity mediated by NF-кB. Additionally, morphological observations of embryos microinjected with Cas9/sgRNA demonstrated that E2F-deficient lamprey embryos displayed embryonic lethality, suggesting that Lr-E2Fs play a significant role in lamprey embryonic development. In summary, our research not only provides new insights into the evolution of Lr-E2Fs but also offers valuable clues regarding their functional roles.

A comprehensive investigation of identifying miRNA biomarkers and their potential role in age-related cataract by meta-analysis and bioinformatics analysis

PURPOSE

Age-related cataract (ARC) remains one of the leading causes of blindness globally. Despite the satisfactory outcomes of surgical interventions, significant disparities in access to medical care prevent many patients from receiving effective treatment. Thus, identifying reliable biomarkers and therapeutic targets to expand treatment options for ARC is essential. Recent evidence indicates that microRNAs (miRNAs) play a role in the development of cataracts and may serve as promising biomarkers. Consequently, this study aims to investigate miRNAs' levels and potential functions in ARC.

METHODS

We conducted a meta-analysis following the PRISMA guidelines by searching three databases from inception to March 31, 2023. The quality of the articles was assessed using the NOS. Subsequently, the targets of the miRNAs identified in the meta-analysis were predicted using six databases, and their GO functions and KEGG pathway enrichment information were analyzed via DAVID.

RESULTS

An initial search yielded 225 publications, from which 22 miRNAs across 37 studies were selected for our meta-analysis. We identified eight differentially expressed miRNAs (DEmiRNAs) in ARC, comprising two up-regulated miRNAs (miR-124 and miR-125a) and six down-regulated miRNAs (miR-15a, miR-23b, miR-34a, miR-221, miR-222, and miR-378a). A total of 972 targets for these miRNAs have been confirmed, and subsequent bioinformatics analysis has revealed their potential functions and pathways in various ARC-related processes.

CONCLUSIONS

This study indicates that eight differentially expressed miRNAs (miRNA-15a, miRNA-23b, miRNA-34a, miRNA-124, miRNA-125a, miRNA-221, miRNA-222, and miRNA-378a) may serve as biomarkers for ARC. Bioinformatics analyses suggest varied potential roles for each miRNA, providing a framework for future research in ARC. This systematic evaluation represents the initial depiction of the miRNA-biomarker landscape in ARC.

KEY MESSAGES

What is known MicroRNAs(miRNAs) could serve as biomarkers for age-related cataract(ARC) since their abundances are associated with ARC and can play a role in cataractogenesis. However, existing studies have reported inconsistent results regarding the miRNA level in ARC. Therefore, achieving a consensus on the role of miRNAs in ARC is essential to clarify their involvement. What is new This study suggested that eight differentially expressed miRNAs (miRNA-15a, miRNA-23b, miRNA-34a, miRNA-124, miRNA-125a, miRNA-221, miRNA-222, and miRNA-378a) may serve as biomarkers for ARC. Our bioinformatics analysis identified various potential roles for each miRNA, which could guide future research on ARC.

Oxidative Stress-Associated Alteration of circRNA and Their ceRNA Network in Differentiating Neuroblasts

Oxidative stress from environmental exposures is thought to play a role in neurodevelopmental disorders; therefore, understanding the underlying molecular regulatory network is essential for mitigating its impacts. In this study, we analysed the competitive endogenous RNA (ceRNA) network mediated by circRNAs, a novel class of regulatory molecules, in an SH-SY5Y cell model of oxidative stress, both prior to and during neural differentiation, using RNA sequencing and in silico analysis. We identified 146 differentially expressed circRNAs, including 93 upregulated and 53 downregulated circRNAs, many of which were significantly co-expressed with mRNAs that potentially interact with miRNAs. We constructed a circRNA-miRNA-mRNA network and identified 15 circRNAs serving as hubs within the regulatory axes, with target genes enriched in stress- and neuron-related pathways, such as signaling by VEGF, axon guidance, signaling by FGFR, and the RAF/MAP kinase cascade. These findings provide insights into the role of the circRNA-mediated ceRNA network in oxidative stress during neuronal differentiation, which may help explain the regulatory mechanisms underlying neurodevelopmental disorders associated with oxidative stress.

Chitosan/PLGA-based tissue engineered nerve grafts with SKP-SC-EVs enhance sciatic nerve regeneration in dogs through miR-30b-5p-mediated regulation of axon growth

Extracellular vesicles from skin-derived precursor Schwann cells (SKP-SC-EVs) promote neurite outgrowth in culture and enhance peripheral nerve regeneration in rats. This study aimed at expanding the application of SKP-SC-EVs in nerve grafting by creating a chitosan/PLGA-based, SKP-SC-EVs-containing tissue engineered nerve graft (TENG) to bridge a 40-mm long sciatic nerve defect in dogs. SKP-SC-EVs contained in TENGs significantly accelerated the recovery of hind limb motor and electrophysiological functions, supported the outgrowth and myelination of regenerated axons, and alleviated the denervation-induced atrophy of target muscles in dogs. To clarify the underlying molecular mechanism, we observed that SKP-SC-EVs were rich in a variety of miRNAs linked to the axon growth of neurons, and miR-30b-5p was the most important among others. We further noted that miR-30b-5p contained within SKP-SC-EVs exerted nerve regeneration-promoting effects by targeting the Sin3a/HDAC complex and activating the phosphorylation of ERK, STAT3 or CREB. Our findings suggested that SKP-SC-EVs-incorporating TENGs represent a novel type of bioactive material with potential application for peripheral nerve repair in the clinic.

Expression of microRNAs related to apoptosis in the aqueous humor and lens capsule of patients with glaucoma

Background

The aim of this study is to investigate the expression profiles of microRNAs (miRNAs) related to apoptosis in the aqueous humor (AH) and lens capsule (LC) of patients with glaucoma.

Methods

AH and LC samples were collected from patients with open-angle glaucoma and control participants who were scheduled for cataract surgery. A miRNA PCR array comprising 84 miRNAs was used to analyze the AH (glaucoma, n = 3; control, n = 3) and LC samples (glaucoma, n = 3; control, n = 4). Additionally, the AH and LC samples (glaucoma, n = 3; control, n = 4) were subjected to quantitative real-time PCR to validate the differentially expressed miRNAs determined using the PCR array. Bioinformatics analysis was performed to identify the interactions between miRNAs and diseases. Additionally, the differential expression of these miRNAs and the target gene was validated through in vitro experiments using a retinal ganglion cell (RGC) model.

Results

Expression levels of 19 and 3 miRNAs were significantly upregulated in the AH and LC samples of the glaucoma group, respectively (p < 0.05). Of these, the expression levels of hsa-miR-193a-5p and hsa-miR-222-3p showed significant differences in both AH and LC samples. Bioinformatics analysis showed experimentally validated 8 miRNA:gene pairs. Among them, PTEN was selected to analyze the expression level in AH and LC from separate cohort (glaucoma, n = 5; control, n = 4). The result showed downregulation of PTEN concurrent with upregulation of the two miRNAs in LC samples of glaucoma group. In vitro experiments validated that the expression levels of hsa-miR-193a-5p and hsa-miR-222-3p were significantly upregulated, and that of PTEN was significantly downregulated in the H2O2-treated RGC, while the level of PTEN was recovered through co-treatment with miR-193a inhibitor or miR-222 inhibitor.

Conclusion

This is the first study to investigate the differential expression of apoptosis-related miRNAs in the AH and LC of patients with glaucoma. Hsa-miR-193a-5p and hsa-miR-222-3p, which were upregulated in both AH and LC, may be considered potential biomarkers for glaucoma.

Circ-CARD6 inhibits oxidative stress-induced apoptosis and autophagy in ARPE-19 cells via the miR-29b-3p/PRDX6/PI3K/Akt axis

BACKGROUND

Oxidative stress-induced damage and dysfunction of retinal pigment epithelium (RPE) cells are important pathogenetic factors of age-related macular degeneration (AMD) and hereditary retinopathy diseases (HRDs). This study aimed to elucidate the roles and mechanisms of circ-CARD6 and miR-29b-3p in oxidative stress-induced RPE and provide new ideas for the diagnosis and treatment of retinopathy disease (RD).

METHODS

A model of oxidative stress-induced RPE (ARPE-19) was established, and the level of malondialdehyde (MDA) and concentration of reactive oxygen species (ROS) were detected by a DCFH-DA fluorescent probe and MDA kit. The cell viability was measured by a CCK-8 assay. The expression of PRDX6/PI3K/Akt axis genes and proteins related to apoptosis and autophagy were determined by RT‒qPCR and Western blot analyses. The dual-luciferase reporter system confirmed the targeting relationship between miR-29b-3p and circ-CARD6 and between miR-29b-3p and PRDX6.

RESULTS

In H2O2-treated ARPE-19 cells, the expression of circ-CARD6 and PRDX6 was decreased, while the expression of miR-29b-3p was increased. The overexpression of circ-CARD6 inhibits oxidative stress-induced increases in ROS, apoptosis and autophagy in ARPE-19 cells. circ-CARD6 targets miR-29b-3p, miR-29b-3p targets PRDX6, and circ-CARD6 regulates PRDX6 via miR-29b-3p. Further studies showed that circ-CARD6 acts as a competitive endogenous RNA of miR-29b-3p to affect the expression of PRDX6, thereby inhibiting autophagy and apoptosis in ARPE-19 cells.

CONCLUSION

circ-CARD6 can inhibit oxidative stress and apoptosis by regulating the miR-29b-3p/PRDX6/PI3K/Akt axis.

Role of Increased miR-222-3p Expression in Peripheral Blood and Wound Marginal Tissues of Type 2 Diabetes Mellitus Patients with Diabetic Foot Ulcer

Purpose

To study the correlations of miR-222-3p expression in the peripheral blood and wound marginal tissues of type 2 diabetes mellitus (T2DM) patients with the onset of diabetic foot ulcer (DFU), as well as explore the clinical value possessed by miR-222-3p in the diagnosis and treatment outcomes of DFU.

Methods

The study included 70 T2DM patients who did not suffer foot ulcers (T2DM group), 146 T2DM patients who suffered foot ulcers (DFU group), as well as 70 normal controls (NC group). Quantitative real-time PCR determined the MiR-222-3p relative expression. Clinical features and risk factors regarding DFU were assessed. Multiple stepwise logistic regression analysis assisted in confirming whether miR-222-3p expression could serve for independently predicting the risk factors for DFU. ROC curve analysis evaluated the diagnostic value exhibited by miR-222-3p level against DFU.

Results

T2DM group exhibited an obviously higher MiR-222-3p expression relative to NC group [1.98 (0.98, 3.62) vs 0.92 (0.61, 1.87)] (P < 0.01), but DFU group exhibited an obviously higher miR-222-3p expression relative to T2DM group [5.61 (1.98, 10.24) vs 1.98 (0.98, 3.62)] (P < 0.01). Besides, miR-222-3p expression presented a negative correlation with DFU healing rate (P < 0.05). According to Kaplan-Meier survival curve analysis, the group with high miR-222-3p expression showed higher unhealed DFU cumulative rate relative to the group with low expression (log-rank, P = 0.011, 0.001, respectively). Multivariate logistic regression analysis confirmed that high miR-222-3p expressions could independently predict DFU risk (OR=3.85, 95% CI 1.18~12.37, P = 0.008). According to the ROC curve analysis, the AUC of miR-222-3p specific to DFU diagnosis reached 0.803, with the best sensitivity of 95.93% and best specificity of 96.27%.

Conclusion

The increased expression of miR-222-3p in the peripheral blood of T2DM patients is closely related to the occurrence of DFU. MiR-222-3p is a biomarker with potential clinical value in diagnosing and evaluating the prognosis of DFU.

CircMAP3K4 protects human lens epithelial cells from H2O2-induced dysfunction by targeting miR-193a-3p/PLCD3 axis in age-related cataract

Circular RNAs (circRNAs) have shown pivotal regulatory roles in multiple human ocular diseases, including age-related cataract (ARC). Here, we explored the role of circRNA mitogen-activated protein kinase kinase kinase 4 (circMAP3K4, hsa_circ_0078619) in ARC pathology and its associated mechanism. The expression of RNAs and proteins was examined by reverse transcription-quantitative polymerase chain reaction (RT-qPCR) and western blot assay. Cell viability, senescence, proliferation, and apoptosis were analyzed by 3-(4,5-Dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay, senescence-associated-β-galactosidase (SA-β-Gal) staining, 5-ethynyl-20-deoxyuridine (EdU) assay, and flow cytometry. The oxidative stress status of SRA01/04 cells was analyzed using the commercial kits. The interaction between microRNA-193a-3p (miR-193a-3p) and circMAP3K4 or phospholipase C delta 3 (PLCD3) was verified by dual-luciferase reporter assay, RNA immunoprecipitation (RIP) assay, and RNA-pull down assay. CircMAP3K4 was significantly down-regulated in ARC patients and H2O2-induced SRA01/04 cells. H2O2 treatment restrained the viability and proliferation and promoted the senescence, apoptosis, and oxidative stress of SRA01/04 cells, and circMAP3K4 overexpression protected SRA01/04 cells from H2O2-induced dysfunction. MiR-193a-3p was a direct target of circMAP3K4, and circMAP3K4 overexpression-mediated protective effects in H2O2-induced SRA01/04 cells were largely reversed by the accumulation of miR-193a-3p. MiR-193a-3p interacted with the 3' untranslated region (3'UTR) of PLCD3, and PLCD3 knockdown largely overturned miR-193a-3p silencing-induced protective effects in H2O2-induced SRA01/04 cells. CircMAP3K4 up-regulated the expression of PLCD3 via sponging miR-193a-3p in SRA01/04 cells. In conclusion, circMAP3K4 protected SRA01/04 cells from H2O2-induced dysfunction in ARC through mediating miR-193a-3p/PLCD3 axis.

Suppression of microRNA-222-3p ameliorates ulcerative colitis and colitis-associated colorectal cancer to protect against oxidative stress via targeting BRG1 to activate Nrf2/HO-1 signaling pathway

Oxidative stress is an important pathogenic factor in ulcerative colitis (UC) and colitis-associated colorectal cancer (CAC), further impairing the entire colon. Intestinal epithelial cells (IECs) are crucial components of innate immunity and play an important role in maintaining intestinal barrier function. Recent studies have indicated that microRNA-222-3p (miR-222-3p) is increased in colon of UC and colorectal cancer (CRC) patients, and miR-222-3p is a crucial regulator of oxidative stress. However, whether miR-222-3p influences IEC oxidative stress in UC and CAC remains unknown. This study investigated the effect of miR-222-3p on the regulation of IEC oxidative stress in UC and CAC. An in vitro inflammation model was established in NCM460 colonic cells, mouse UC and CAC models were established in vivo, and IECs were isolated. The biological role and mechanism of miR-222-3p-mediated oxidative stress in UC and CAC were determined. We demonstrated that miR-222-3p expression was notably increased in dextran sulfate sodium (DSS)-induced NCM460 cells and IECs from UC and CAC mice. In vitro, these results showed that the downregulation of miR-222-3p reduced oxidative stress, caspase-3 activity, IL-1β and TNF-α in DSS-induced NCM460 cells. We further identified BRG1 as the target gene of miR-222-3p, and downregulating miR-222-3p alleviated DSS-induced oxidative injury via promoting BRG1-mediated activation Nrf2/HO-1 signaling in NCM460 cells. The in vivo results demonstrated that inhibiting miR-222-3p in IECs significantly relieved oxidative stress and inflammation in the damaged colons of UC and CAC mice, as evidenced by decreases in ROS, MDA, IL-1β and TNF-α levels and increases in GSH-Px levels. Our study further demonstrated that inhibiting miR-222-3p in IECs attenuated oxidative damage by targeting BRG1 to activate the Nrf2/HO-1 signaling. In summary, inhibiting miR-222-3p in IECs attenuates oxidative stress by targeting BRG1 to activate the Nrf2/HO-1 signaling, thereby reducing colonic inflammation and tumorigenesis.

The Differential Expression of Circular RNAs and the Role of circAFF1 in Lens Epithelial Cells of High-Myopic Cataract

High-myopic cataract (HMC) is a complex cataract with earlier onset and more rapid progress than age-related cataract (ARC). Circular RNAs (circRNAs) have been implicated in many diseases. However, their involvement in HMC remain largely unexplored. To investigate the role of dysregulated circRNAs in HMC, lens epithelium samples from 24 HMC and 24 ARC patients were used for whole transcriptome sequencing. Compared with ARC, HMC had 3687 uniquely expressed circRNAs and 1163 significantly differentially expressed circRNAs (DEcRs) (|log₂FC| > 1, p < 0.05). A putative circRNA-miRNA-mRNA network was constructed based on correlation analysis. We validated the differential expression of 3 DEcRs by quantitative polymerase chain reaction (qPCR) using different sets of samples. We further investigated the role of circAFF1 in cultured lens epithelial cells (LECs) and found that the overexpression of circAFF1 promoted cell proliferation, migration and inhibited apoptosis. We also showed that circAFF1 upregulated Tropomyosin 1 (TPM1) expression by sponging miR-760, which was consistent with the network prediction. Collectively, our study suggested the involvement of circRNAs in the pathogenesis of HMC and provide a resource for further study on this topic.

METTL3-mediated m6A modification of has_circ_0007905 promotes age-related cataract progression through miR-6749-3p/EIF4EBP1

Many cases of blindness are caused by age-related cataracts (ARCs). N6-methyladenosine (m6A)-modified circRNA widely participates in disease progression. However, the role of m6A modification of circRNA in ARC is unclear. We mined and elucidated the functions and mechanisms of key circRNAs with m6A modification involved in ARC progression. The GSE153722 dataset was used to mine m6A-mediated key circRNA. Loss-of-function assays and rescue assays were used to explore the effect and mechanism of circRNA on ARC cell proliferation and apoptosis. Has_circ_0007905 was a hypermethylated and upregulated expression in the ARC group relative to the control group both in vivo and in vitro. Silencing of has_circ_0007905 promoted proliferation and inhibited the apoptosis of HLE-B3 cells. METTL3 was upregulated in HLE-B3 cells after ARC modeling and had four binding sites with has_circ_0007905 and a mediated m6A modification of has_circ_0007905. Proliferation was significantly inhibited and apoptosis of HLE-B3 cells was facilitated by METTL3 overexpression, whereas these effects were prevented by has_circ_0007905 silencing. Silencing of has_circ_0007905 led to an alteration in the transcriptome landscape. Differentially expressed genes were mainly involved in immune-related processes and pathways. EIF4EBP1 overexpression promoted apoptosis and suppressed proliferation, and also significantly reversed effects of has_circ_0007905 silencing. Moreover, miR-6749-3p significantly decreased the luciferase activities of wild type plasmids with both of has_circ_0007905 and EIF4EBP1. MiR-6749-3p inhibitor blocked elevation in proliferation and reduced EIF4EBP1 expression and apoptosis conferred by has_circ_0007905 silencing. We reveal for the first time that the commitment of ARC progression is guided by METTL3/has_circ_0007905/miR-6749-3p/EIF4EBP1 axis, and the results provide new insights into ARC pathology.

Noncoding RNAs in cataract formation: star molecules emerge in an endless stream

For decades, research on the pathological mechanism of cataracts has usually focused on the abnormal protein changes caused by a series of risk factors. However, an entire class of molecules, termed non-coding RNA (ncRNA), was discovered in recent years and proven to be heavily involved in cataract formation. Recent studies have recognized the key regulatory roles of ncRNAs in cataracts by shaping cellular activities such as proliferation, apoptosis, migration and epithelial-mesenchymal transition (EMT). This review summarizes our current insight into the biogenesis, properties and functions of ncRNAs and then discusses the development of research on ncRNAs in cataracts. Considering the significant role of ncRNA in cataract formation, research on novel associated regulatory mechanisms is urgently needed, and the development of therapeutic alternatives for the treatment of cataracts seems promising.

XRCC5 downregulated by TRIM25 is susceptible for lens epithelial cell apoptosis

Exposure of the lens to UVB can lead to oxidative stress, which would result in age-related cataract (ARC) formation. In this study, we investigate the regulatory mechanism of tripartite motif containing 25 (TRIM25) in ARC. The protein level of TRIM25 was elevated in ARC specimens and UVB-exposed SRA01/04 cells. Bioinformatic analysis indicated that X-ray repair cross complementing 5 (XRCC5) might interact with TRIM25, and the interaction was validated via immunoprecipitation. TRIM25 interacted with XRCC5 and ubiquitinated it for degradation. Further studies showed that XRCC5 overexpression notably repressed UVB-induced apoptosis, while XRCC5 knockdown promoted apoptosis. Of note, ubiquitination of XRCC5 mediated by TRIM25 overexpression facilitated apoptosis. Attenuation of XRCC5 ubiquitination by mutant with substitution of lysine residues with arginine residues rescued its anti-apoptosis effect. Moreover, we observed that TRIM25-mediated XRCC5 degradation was reversed by proteasome inhibitor MG-132 or lysosome inhibitor 3-MA. In conclusion, TRIM25 mediates ubiquitination of XRCC5 to regulate the function and degradation of XRCC5, suggesting that interventions targeting TRIM25 might be a promising therapeutic strategy for ARC.

Circular RNA erythrocyte membrane protein band 4.1 assuages ultraviolet irradiation-induced apoptosis of lens epithelial cells by stimulating 5'-bisphosphate nucleotidase 1 in a miR-24-3p-dependent manner

Apoptosis of lens epithelial cells contributed to the formation of age-related cataract (ARC), and previous data revealed that circular RNA (circRNA) was responsible for the underneath mechanism. The study was organized to explore the role of circular RNA erythrocyte membrane protein band 4.1 (circ_EPB41) in ultraviolet (UV) irradiation-induced apoptosis of lens epithelial cells. SRA01/04 cells were irradiated with UV to mimic the ARC cell model. The RNA levels of circ_EPB41, microRNA-24-3p (miR-24-3p), and 3ʹ(2ʹ), 5ʹ-bisphosphate nucleotidase 1 (BPNT1) were detected by quantitative real-time polymerase chain reaction. Protein expression was checked by western blot. 5-Ethynyl-29-deoxyuridine, 3-(4,5-Dimethylthazol-2-yl)-2,5-diphenyltetrazolium bromide and DNA content quantitation assays were performed to investigate cell proliferation. Flow cytometry was conducted to analyze cell apoptosis. Dual-luciferase reporter assay was implemented to confirm the interaction among circ_EPB41, miR-24-3p, and BPNT1. Our data showed that circ_EPB41 and BPNT1 expression were downregulated in ARC tissues and UV-irradiated SRA01/04 cells as compared with normal anterior lens capsules and untreated SRA01/04 cells. Circ_EPB41 overexpression ameliorated the effects of UV irradiation on the proliferation and apoptosis of SRA01/04 cells. Besides, miR-24-3p, a target miRNA of circ_EPB41, attenuated circ_EPB41 introduction-mediated proliferation, and apoptosis of UV-irradiated SRA01/04 cells. MiR-24-3p regulated UV irradiation-induced effects by targeting BPNT1. Importantly, it was found that circ_EPB41 stimulated BPNT1 production by miR-24-3p. Taken together, the enforced expression of circ_EPB41 ameliorated UV irradiation-induced apoptosis of lens epithelial cells by miR-24-3p/BPNT1 pathway, providing us with a potential target for the therapy of UV-caused ARC.

Circ_0122396 Protects Human Lens Epithelial Cells from Hydrogen Peroxide-induced Injury by Binding to miR-15a-5p to Stimulate FGF1 Expression

BACKGROUND

Circular_0122396 (circ_0122396) has been reported to be downregulated in age-related cataract (ARC); however, the underlying mechanism remains unknown. The study aimed to reveal the role of circ_0122396 in ARC progression and underneath mechanism.

METHODS

Hydrogen peroxide (H₂O₂) was employed to induce lens epithelial cells (SRA01/04) injury. The RNA expression of circ_0122396, microRNA-15a-5p (miR-15a-5p) and fibroblast growth factor 1 (FGF1) was detected by quantitative real-time polymerase chain reaction. Protein expression was checked by western blot. Cell viability, proliferation and apoptosis were investigated by 3-(4,5-Dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide, 5-Ethynyl-29-deoxyuridine and flow cytometry analysis, respectively. Oxidative stress was evaluated by superoxide dismutase and catalase activity assay kits and lipid peroxidation malondialdehyde assay kit. Online databases and mechanism assays were used to predict and identify the relationship between miR-15a-5p and circ_0122396 or FGF1.

RESULTS

Circ_0122396 and FGF1 expression were significantly downregulated, but miR-15a-5p expression was upregulated in ARC tissues or/and H₂O₂-treated SRA01/04 cells in comparison with control groups. H₂O₂ treatment repressed cell proliferation and induced cell apoptosis and oxidative stress, which was attenuated after circ_0122396 overexpression. MiR-15a-5p, a target mRNA of circ_0122396, was found to participate in H₂O₂-triggered cell damage by interacting with circ_0122396. Additionally, FGF1 silencing attenuated miR-15a-5p inhibitors-mediated action. Importantly, circ_0122396 regulated FGF1 expression by interaction with miR-15a-5p in H₂O₂-treated SRA01/04 cells.

CONCLUSION

Circ_0122396 ameliorated H₂O₂-triggered cell injury by inducing FGF1 through sponging miR-15a-5p, providing a potential target for ARC therapy.