UHRF2 promotes intestinal tumorigenesis through stabilization of TCF4 mediated Wnt/β-catenin signaling

TCF4 promotes apoptosis and Wnt/β-catenin signaling pathway in acute kidney injury via transcriptional regulation of COX7A2L

BACKGROUND

Acute kidney injury (AKI) is still a serious kidney illness with high morbidity and death rates, and it's crucial to comprehend the underlying molecular causes.

METHODS

Bioinformatics analysis was performed on GSE139061 and GSE30718 data sets, and COX7A2L was screened out. The role of COX7A2L in H/R-treated cells and its transcriptional regulation with TCF4 were assessed. In vitro experiments analyzed the regulation of COX7A2L and TCF4 on the proliferation, apoptosis, and Wnt/β-catenin signaling pathway of H/R-treated cells.

RESULTS

COX7A2L as a hub gene was downregulated in AKI samples. In H/R-treated cells, COX7A2L overexpression inhibited apoptosis and promoted cell proliferation, while COX7A2L knockdown promoted apoptosis and inhibited cell proliferation. Notably, TCF4 exhibited a significant positive correlation with COX7A2L. TCF4 overexpression-induced apoptosis was lessened and improved cell proliferation was countered by COX7A2L knockdown, according to rescue study findings. Besides, we discovered that TCF4 overexpression increased the expression of proteins linked to the Wnt/β-catenin signaling pathway (c-myc, β-catenin, and cyclin D1), while underexpression of COX7A2L counteracted this effect.

CONCLUSION

The study revealed the pivotal role of COX7A2L in AKI, which is regulated by TCF4 and modulates the Wnt/β-catenin signaling pathway, highlighting its potential as a therapeutic target.

SUMOylation at the crossroads of gut health: insights into physiology and pathology

SUMOylation, a post-translational modification involving the covalent attachment of small ubiquitin-like modifier (SUMO) proteins to target substrates, plays a pivotal role at the intersection of gut health and disease, influencing various aspects of intestinal physiology and pathology. This review provides a comprehensive examination of SUMOylation's diverse roles within the gut microenvironment. We examine its critical roles in maintaining epithelial barrier integrity, regulating immune responses, and mediating host-microbe interactions, thereby highlighting the complex molecular mechanisms that underpin gut homeostasis. Furthermore, we explore the impact of SUMOylation dysregulation in various intestinal disorders, including inflammatory bowel diseases and colorectal cancer, highlighting its implications as a potential diagnostic biomarker and therapeutic target. By integrating current research findings, this review offers valuable insights into the dynamic interplay between SUMOylation and gut health, paving the way for novel therapeutic strategies aimed at restoring intestinal equilibrium and combating associated pathologies.

The prognostic value of ubiquitin/ubiquitin-like-related genes along with immune cell infiltration and clinicopathological features in osteosarcoma

BACKGROUND

Ubiquitin/ubiquitin-like (Ub/UBL)-related genes have been reported to be associated with the survival of osteosarcoma patients but have not yet been systematically explored.

METHODS

The prognostic value of Ub/UBL-related genes, immune cell infiltration and clinicopathological features of patients were explored by Cox and LASSO regression analyses. A prognostic model was established and then validated in the GSE21257 dataset. The differential expression of hub genes in osteosarcoma was confirmed by qRT-PCR, western blotting and immunohistochemistry.

RESULTS

Tripartite Motif Containing 8 (TRIM8) and Ubiquitin Like With PHD And Ring Finger Domains 2 (UHRF2) were screened as genes with prognostic value in osteosarcoma. Kaplan-Meier analysis and scatter plots indicated that patients in the high gene significance score group tended to have a worse prognosis. The concordance index, calibration analysis and receiver operating characteristic analysis suggested that the model had good prediction accuracy and high sensitivity and specificity. Decision curve analysis revealed that patients could obtain greater net benefit from this model. Functional analyses of the differentially expressed genes indicated that they were involved in important functions and pathways. TRIM8 and UHRF2 were confirmed to be highly expressed in osteosarcoma cell lines and tissues.

CONCLUSIONS

TRIM8 and UHRF2 are potential prognostic genes in osteosarcoma, and these results provide insights into the roles of these genes and their implications for patient outcomes.

UHRF2 accumulates in early G1-phase after serum stimulation or mitotic exit to extend G1 and total cell cycle length

Ubiquitin like with PHD and ring finger domains 2 (UHRF2) regulates the cell cycle and epigenetics as a multi-domain protein sharing homology with UHRF1. UHRF1 functions with DNMT1 to coordinate daughter strand methylation during DNA replication, but UHRF2 can't perform this function, and its roles during cell cycle progression are not well defined. UHRF2 role as an oncogene vs. tumor suppressor differs in distinct cell types. UHRF2 interacts with E2F1 to control Cyclin E1 (CCNE1) transcription. UHRF2 also functions in a reciprocal loop with Cyclin E/CDK2 during G1, first as a direct target of CDK2 phosphorylation, but also as an E3-ligase with direct activity toward both Cyclin E and Cyclin D. In this study, we demonstrate that UHRF2 is expressed in early G1 following either serum stimulation out of quiescence or in cells transiting directly out of M-phase, where UHRF2 protein is lost. Further, UHRF2 depletion in G2/M is reversed with a CDK1 specific inhibitor. UHRF2 controls expression levels of cyclins and CDK inhibitors and controls its own transcription in a negative-feedback loop. Deletion of UHRF2 using CRISPR/Cas9 caused a delay in passage through each cell cycle phase. UHRF2 loss culminated in elevated levels of cyclins but also the CDK inhibitor p27KIP1, which regulates G1 passage, to reduce retinoblastoma phosphorylation and increase the amount of time required to reach G1/S passage. Our data indicate that UHRF2 is a central regulator of cell-cycle pacing through its complex regulation of cell cycle gene expression and protein stability.

Role of non-canonical post-translational modifications in gastrointestinal tumors

Post-translational modifications (PTMs) of proteins contribute to the occurrence and development of tumors. Previous studies have suggested that canonical PTMs such as ubiquitination, glycosylation, and phosphorylation are closely implicated in different aspects of gastrointestinal tumors. Recently, emerging evidence showed that non-canonical PTMs play an essential role in the carcinogenesis, metastasis and treatment of gastrointestinal tumors. Therefore, we summarized recent advances in sumoylation, neddylation, isoprenylation, succinylation and other non-canonical PTMs in gastrointestinal tumors, which comprehensively describe the mechanisms and functions of non-classical PTMs in gastrointestinal tumors. It is anticipated that targeting specific PTMs could benefit the treatment as well as improve the prognosis of gastrointestinal tumors.

SUMO1 degrader induces ER stress and ROS accumulation through deSUMOylation of TCF4 and inhibition of its transcription of StarD7 in colon cancer

Small molecule degraders of small ubiquitin-related modifier 1 (SUMO1) induce SUMO1 degradation in colon cancer cells and inhibits the cancer cell growth; however, it is unclear how SUMO1 degradation leads to the anticancer activity of the degraders. Genome-wide CRISPR-Cas9 knockout screen has identified StAR-related lipid transfer domain containing 7 (StarD7) as a critical gene for the degrader's anticancer activity. Here, we show that both StarD7 mRNA and protein are overexpressed in human colon cancer and its knockout significantly reduces colon cancer cell growth and xenograft progression. The treatment with the SUMO1 degrader lead compound HB007 reduces StarD7 mRNA and protein levels and increases endoplasmic reticulum (ER) stress and reactive oxygen species (ROS) production in colon cancer cells and three-dimensional (3D) organoids. The study further provides a novel mechanism of the compound anticancer activity that SUMO1 degrader-induced decrease of StarD7 occur through degradation of SUMO1, deSUMOylation and degradation of T cell-specific transcription 4 (TCF4) and thereby inhibition of its transcription of StarD7 in colon cancer cells, 3D organoids and patient-derived xenografts (PDX).

Natural and Synthetic Anticancer Epidrugs Targeting the Epigenetic Integrator UHRF1

Cancer is one of the leading causes of death worldwide, and its incidence and mortality are increasing each year. Improved therapeutic strategies against cancer have progressed, but remain insufficient to invert this trend. Along with several other risk factors, abnormal genetic and epigenetic regulations play a critical role in the initiation of cellular transformation, as well as tumorigenesis. The epigenetic regulator UHRF1 (ubiquitin-like, containing PHD and RING finger domains 1) is a multidomain protein with oncogenic abilities overexpressed in most cancers. Through the coordination of its multiple domains and other epigenetic key players, UHRF1 regulates DNA methylation and histone modifications. This well-coordinated dialogue leads to the silencing of tumor-suppressor genes (TSGs) and facilitates tumor cells' resistance toward anticancer drugs, ultimately promoting apoptosis escape and uncontrolled proliferation. Several studies have shown that the downregulation of UHRF1 with natural compounds in tumor cells induces the reactivation of various TSGs, inhibits cell growth, and promotes apoptosis. In this review, we discuss the underlying mechanisms and the potential of various natural and synthetic compounds that can inhibit/minimize UHRF1's oncogenic activities and/or its expression.

Impaired Repopulating Ability of Uhrf2-/- Hematopoietic Progenitor Cells in Mice

UHRF proteins catalyze the ubiquitination of target proteins and are involved in regulating gene expression. Some studies reported a reduced expression of UHRF2 in acute leukemia cells, but the role of UHRF2 in hematopoiesis remains unknown. Here, we generated Uhrf2-/- mice to clarify the role of UHRF2 deletion in hematopoiesis. Compared to Uhrf2+/+ mice, Uhrf2-/- mice showed no differences in complete blood counts, as well as bone marrow (BM) findings and spleen weights. Proportions of cells in progenitor fractions in BM were comparable between Uhrf2+/+ mice and Uhrf2-/- mice. However, in competitive repopulation assays with BM transplants (BMT), the proportions of Uhrf2-/- cells were decreased relative to Uhrf2+/+ cells in all lineages. After the second BMT, Uhrf2-/- neutrophils were few, while 20-30% of Uhrf2-/- T cells and B cells were still detected. RNA sequencing showed downregulation of some genes associated with stem-cell function in Uhrf2-/- hematopoietic stem/progenitor cells (HSPCs). Interestingly, trimethylated histone H3 lysine 9 was increased in Uhrf2-/- HSPCs in a cleavage under targets and tagmentation assay. While UHRF2 deletion did not cause hematologic malignancy or confer a growth advantage of HSPCs, our results suggest that UHRF2 may play a role in the regulation of hematopoiesis.

UHRF2 promotes the malignancy of hepatocellular carcinoma by PARP1 mediated autophagy

Autophagy have critical implications in the proliferation and metastasis of HCC. In the current study, we aimed to explore the underlying mechanisms of UHRF2 regulates HCC cell autophagy and HCC progression. We initially determined the relationship between UHRF2 and HCC autophagy, oncogenicity and patient survival through GSEA database and TCGA database. We mainly investigated the effect of UHRF2 on HCC development and autophagy through western blot, electron microscopy, and immunofluorescence. Functionally, UHRF2 was positively involved in the autophagy activation. Overexpression of UHRF2 reduced apoptosis in HCC cells, and promote the malignancy phenotype of HCC both in vitro and in vivo. Mechanistically, PRDX1 bound to UHRF2 and upregulated its protein expression to facilitate the biological function of UHRF2 in HCC. Meanwhile, UHRF2 bound to autophagy-related protein PARP1 and upregulated PARP1 protein level. The results showed that UHRF2 promoted autophagy and contributed to the malignant phenotype of hepatocellular carcinoma by regulating PARP1 levels. In summary, a novel interaction between PRDX1, UHRF2, and PARP1 was revealed, suggesting that UHRF2 could inspire a potential biomarker and potential therapeutic target for HCC.

The Role of RNA Methylation Modification Related Genes in Prognosis and Immunotherapy of Colorectal Cancer

Background

Researches showed RNA methylation genes can affect the prognosis of tumors. Thus, the study aimed to comprehensively analyze the effects of RNA methylation regulatory genes in prognosis and treatment of colorectal cancer (CRC).

Methods

Prognostic signature associated with CRCs were constructed by differential expression analysis, Cox and Least Absolute Shrinkage and Selection Operator (LASSO) analyses. Receiver operating characteristic (ROC) and Kaplan-Meier survival analyses were used to validate the reliability of the developed model. Gene Ontology (GO), Gene set variation analysis (GSVA), and the Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway analysis were performed for functional annotation. Finally, normal and cancerous tissue were collected to validate gene by quantitative real-time PCR (qRT-PCR).

Results

A prognostic risk model based on leucine rich pentatricopeptide repeat containing (LRPPRC) and ubiquitin-like with PHD and ring finger domains 2 (UHRF2) was constructed and relevant to the overall survival (OS) of CRC. Functional enrichment analysis revealed that collagen fibrous tissue, ion channel complex and other pathways were significantly enriched, which might help explain the underlying molecular mechanisms. There were significant differences in ImmuneScore, StromalScore, ESTIMATEScore between high- and low-risk groups (p < 0.05). Ultimately, qRT-PCR validation showed that a significant upregulation in the expression of LRPPRC and UHRF2 in cancerous tissue, which verified the effectiveness of our signature.

Conclusion

In conclusion, 2 prognostic genes (LRPPRC and UHRF2) related to RNA methylation were identified by bioinformatics analysis, which might supply a new insight into the treatment and evaluation of CRC.

Protein sumoylation in normal and cancer stem cells

Stem cells with the capacity of self-renewal and differentiation play pivotal roles in normal tissues and malignant tumors. Whereas stem cells are supposed to be genetically identical to their non-stem cell counterparts, cell stemness is deliberately regulated by a dynamic network of molecular mechanisms. Reversible post-translational protein modifications (PTMs) are rapid and reversible non-genetic processes that regulate essentially all physiological and pathological process. Numerous studies have reported the involvement of post-translational protein modifications in the acquirement and maintenance of cell stemness. Recent studies underscore the importance of protein sumoylation, i.e., the covalent attachment of the small ubiquitin-like modifiers (SUMO), as a critical post-translational protein modification in the stem cell populations in development and tumorigenesis. In this review, we summarize the functions of protein sumoylation in different kinds of normal and cancer stem cells. In addition, we describe the upstream regulators and the downstream effectors of protein sumoylation associated with cell stemness. We also introduce the translational studies aiming at sumoylation to target stem cells for disease treatment. Finally, we propose future directions for sumoylation studies in stem cells.

Integrative analysis of immune-related multi-omics profiles identifies distinct prognosis and tumor microenvironment patterns in osteosarcoma

Osteosarcoma (OS) is the most common primary malignancy of bone. Epigenetic regulation plays a pivotal role in cancer development in various aspects, including immune response. In this study, we studied the potential association of alterations in the DNA methylation and transcription of immune-related genes with changes in the tumor microenvironment (TME) and tumor prognosis of OS. We obtained multi-omics data for OS patients from the Therapeutically Applicable Research to Generate Effective Treatments (TARGET) and Gene Expression Omnibus (GEO) databases. By referring to curated immune signatures and using a consensus clustering method, we categorized patients based on immune-related DNA methylation patterns (IMPs), and evaluated prognosis and TME characteristics of the resulting patient subgroups. Subsequently, we used a machine-learning approach to construct an IMP-associated prognostic risk model incorporating the expression of a six-gene signature (MYC, COL13A1, UHRF2, MT1A, ACTB, and GBP1), which was then validated in an independent patient cohort. Furthermore, we evaluated TME patterns, transcriptional variation in biological pathways, somatic copy number alteration, anticancer drug sensitivity, and potential responsiveness to immune checkpoint inhibitor therapy with regard to our IMP-associated signature scoring model. By integrative IMP and transcriptomic analysis, we uncovered distinct prognosis and TME patterns in OS. Finally, we constructed a classifying model, which may aid in prognosis prediction and provide a potential rationale for targeted- and immune checkpoint inhibitor therapy in OS.

UHRF2 regulates cell cycle, epigenetics and gene expression to control the timing of retinal progenitor and ganglion cell differentiation

Ubiquitin-like, containing PHD and RING finger domains 2 (UHRF2) regulates cell cycle and binds 5-hydroxymethylcytosine (5hmC) to promote completion of DNA demethylation. Uhrf2-/- mice are without gross phenotypic defects; however, the cell cycle and epigenetic regulatory functions of Uhrf2 during retinal tissue development are unclear. Retinal progenitor cells (RPCs) produce all retinal neurons and Müller glia in a predictable sequence controlled by the complex interplay between extrinsic signaling, cell cycle, epigenetic changes and cell-specific transcription factor activation. In this study, we find that UHRF2 accumulates in RPCs, and its conditional deletion from mouse RPCs reduced 5hmC, altered gene expressions and disrupted retinal cell proliferation and differentiation. Retinal ganglion cells were overproduced in Uhrf2-deficient retinae at the expense of VSX2+ RPCs. Most other cell types were transiently delayed in differentiation. Expression of each member of the Tet3/Uhrf2/Tdg active demethylation pathway was reduced in Uhrf2-deficient retinae, consistent with locally reduced 5hmC in their gene bodies. This study highlights a novel role of UHRF2 in controlling the transition from RPCs to differentiated cell by regulating cell cycle, epigenetic and gene expression decisions.

MiR-196a promotes the proliferation and migration of esophageal cancer via the UHRF2/TET2 axis

The aim of this study was to investigate the functions and molecular mechanism of miR-196a in esophageal cancer (EC). miR-196a as well as UHRF2 and TET2 mRNA and protein levels in EC tissues and cells were detected using quantitative real-time PCR or western blot, respectively. Cell proliferation was evaluated via MTT assay. Transwell assays were used to detect cell migration. In addition, the targeted relationship between miR-196a and UHRF2 was assessed through a dual luciferase reporter assay. Enzyme-linked immunosorbent assay was performed to detect the levels of the cytosine intermediates 5-methylcytosine (5mC) and 5-hydroxymethylcytosine (5hmC). We found increased miR-196a expression in EC tissues and cells but decreased UHRF2 and TET2 expression. Next, functional experiments showed that knockdown of miR-196a or UHRF2 overexpression suppress EC cell proliferation and migration. miR-196a negatively regulates TET2 expression by directly targeting UHRF2. UHRF2 overexpression decreased 5mC levels but increased 5hmC levels. Furthermore, TET2 downregulation reversed the functions of miR-196a inhibition on EC cell proliferation and migration. Collectively, our study suggested that miR-196a was closely related to the progression of EC possibly by regulating the UHRF2/TET2 axis. Thus, miR-196a represents a potential new EC therapeutic target.

The UHRF protein family in epigenetics, development, and carcinogenesis

The UHRF protein family consists of multidomain regulatory proteins that sense modification status of DNA and/or proteins and catalyze the ubiquitylation of target proteins. Through their functional domains, they interact with other molecules and serve as a hub for regulatory networks of several important biological processes, including maintenance of DNA methylation and DNA damage repair. The UHRF family is conserved in vertebrates and plants but is missing from fungi and many nonvertebrate animals. Mammals commonly have UHRF1 and UHRF2, but, despite their high structural similarity, the two paralogues appear to have distinct functions. Furthermore, UHRF1 and UHRF2 show different expression patterns and different outcomes in gene knockout experiments. In this review, we summarize the current knowledge on the molecular function of the UHRF family in various biological pathways and discuss their roles in epigenetics, development, gametogenesis, and carcinogenesis, with a focus on the mammalian UHRF proteins.

Molecular investigation of the tandem Tudor domain and plant homeodomain histone binding domains of the epigenetic regulator UHRF2

Ubiquitin-like containing PHD and ring finger (UHRF)1 and UHRF2 are multidomain epigenetic proteins that play a critical role in bridging crosstalk between histone modifications and DNA methylation. Both proteins contain two histone reader domains, called tandem Tudor domain (TTD) and plant homeodomain (PHD), which read the modification status on histone H3 to regulate DNA methylation and gene expression. To shed light on the mechanism of histone binding by UHRF2, we have undergone a detailed molecular investigation with the TTD, PHD and TTD-PHD domains and compared the binding activity to its UHRF1 counterpart. We found that unlike UHRF1 where the PHD is the primary binding contributor, the TTD of UHRF2 has modestly higher affinity toward the H3 tail, while the PHD has a weaker binding interaction. We also demonstrated that like UHRF1, the aromatic amino acids within the TTD are important for binding to H3K9me3 and a conserved aspartic acid within the PHD forms an ionic interaction with R2 of H3. However, while the aromatic amino acids in the TTD of UHRF1 contribute to selectivity, the analogous residues in UHRF2 contribute to both selectivity and affinity. We also discovered that the PHD of UHRF2 contains a distinct asparagine in the H3R2 binding pocket that lowers the binding affinity of the PHD by reducing a potential electrostatic interaction with the H3 tail. Furthermore, we demonstrate the PHD and TTD of UHRF2 cooperate to interact with the H3 tail and that dual domain engagement with the H3 tail relies on specific amino acids. Lastly, our data indicate that the unique stretch region in the TTD of UHRF2 can decrease the melting temperature of the TTD-PHD and represents a disordered region. Thus, these subtle but important mechanistic differences are potential avenues for selectively targeting the histone binding interactions of UHRF1 and UHRF2 with small molecules.

UHRF2 promotes Hepatocellular Carcinoma Progression by Upregulating ErbB3/Ras/Raf Signaling Pathway

Emerging evidence revealed that UHRF2 was implicated in a variety of human diseases, especially in cancer. However, the biological function, clinical significance and underly mechanisms of UHRF2 in hepatocellular carcinoma (HCC) is largely unknown. We analyzed the expression of UHRF2 in 371 HCC tissues and 50 para-cancerous tissues of TCGA database. We found that UHRF2 was significantly upregulated in HCC tissues, which was further confirmed in HCC cells and tissues by western blot. More importantly, the level of UHRF2 was correlated with pathological grade and clinical stage, and the patients with high level of UHRF2 had lower overall survival, disease-free survival and higher recurrence rate than those with low UHRF2 level. Univariate and multivariate Cox regression analysis revealed that high level of UHRF2 might be an independent prognostic factor for HCC patients. Functional investigations suggested that ectopic expression of UHRF2 could promote the proliferation, migration and invasion of HCC cell lines, whereas knock down of UHRF2 exhibited an opposite effect. Additionally, gene set enrichment analysis indicated that ERBB signaling pathway was upregulated in patients with high level of UHRF2. Pearson correlation analysis indicated that the expression of UHRF2 was positively correlated with ErbB3 and its downstream targets SOS1, Ras and Raf-1. Furthermore, we found that overexpression of UHRF2 could upregulate the expression of ErbB3, SOS1, Ras and Raf-1. Our findings suggested that UHRF2 might accelerate HCC progression by upregulating ErbB3/Ras/Raf signaling pathway and it might serve as a diagnostic marker and therapeutic target for HCC patients.

HBx promotes hepatocarcinogenesis by enhancing phosphorylation and blocking ubiquitinylation of UHRF2

BACKGROUND AND AIMS

The major cause of Hepatocellular carcinoma (HCC) is acute or chronic infection caused by hepatotropic viruses and HBV infection is the main cause. UHRF2, a ubiquitin-protein ligase E3, is associated with cancer development. This study aimed to investigate the connection and mechanism between UHRF2 and HBV-associated HCC.

METHODS

The expression of UHRF2 in human HBV-positive HCC tissues and paracancerous tissues was detected by western blot and tissue microarray. The effects of UHRF2 on invasion, migration and proliferation were detected in HBV-positive hepatoma cell lines. Furthermore, western blot, immunofluorescence, Co-immunoprecipitation and ubiquitination assays were used to explore the relationship and mechanism between UHRF2 and HBV-associated HCC.

RESULTS

HBV-positive HCC tissues had higher UHRF2 expression levels than adjacent non-tumor tissues. The HBV-positive HCC patients with a low UHRF2 level in cancer tissues had longer overall and recurrence-free survival compared with those with a high UHRF2 level. UHRF2 induced invasion, migration and proliferation in human HBV-positive HCC cell lines HepG2.2.15 and Hep AD38(-). HBx, an encoding protein of HBV, maintained the stability of UHRF2 by blocking the ubiquitination of UHRF2. HBx up-regulated CDK2 expression through ETS1. UHRF2 bound to CDK2 directly and enhanced UHRF2 phosphorylation at serine 643.

CONCLUSIONS

These results suggest that HBx-ETS1-CDK2-UHRF2 pathway plays an important role in the pathogenesis of HBV-associated HCC and represents new therapeutic targets for human HCC.

CLINICAL TRIALS REGISTRATION

ChiCTR2000041416.

Down-Regulation of miR-181a-5p Prevents Cerebral Ischemic Injury by Upregulating En2 and Activating Wnt/β-catenin Pathway

PURPOSE

Cerebral ischemic injury contributes to severe dysfunction of the brain, which triggers extremely high mortality and disability. The role of microRNA (miR)-181a-5p is documented in cerebral ischemic injury. Therefore, this study intended to further figure out the mechanism of miR-181a-5p in cerebral ischemic injury.

METHODS

miR-181a-5p expression in middle cerebral artery occlusion (MCAO) mouse model, oxygen-glucose-deprivation/reoxygenation (OGD/R) N2a cell model, and serum from acute ischemic injury (ACI) patients was evaluated using reverse transcription quantitative polymerase chain reaction (RT-qPCR). Gain- and loss-of-function assays were implemented in MCAO mice and OGD/R-induced N2a cells. In mice, the cerebral infarction area was assessed with 2,3,5-triphenyltetrazolium chloride staining, the number of damaged neurons by Nissl staining, and apoptosis by TdT-mediated dUTP-biotin nick end-labeling staining. Moreover, N2a cell apoptosis and proliferation were determined with flow cytometry or 5-ethynyl-2'-deoxyuridine staining, respectively. The expression of En2 and Wnt/β-catenin pathway-related factors was determined with RT-qPCR and Western blot analysis. The targeting relationship between miR-181a-5p and En2 was evaluated by dual luciferase reporter gene assay.

RESULTS

miR-181a-5p was highly expressed in serum of ACI patients, MCAO mice, and OGD/R-induced N2a cells. En2, lowly expressed in MCAO mice, was targeted by miR-181a-5p, and miR-181a-5p down-regulation activated the Wnt/β-catenin pathway. Furthermore, miR-181a-5p inhibition or En2 overexpression reduced cerebral infarction area, the number of damaged neurons, and apoptosis in MCAO mice, and also diminished apoptosis and accelerated proliferation of OGD/R-induced N2a cells.

CONCLUSION

miR-181a-5p suppression activated Wnt/β-catenin pathway and sequentially attenuated cerebral ischemic injury by targeting En2.