Objective To construct a dual-luciferase reporter gene vector and validate the targeting relation ship between miR-299 and the COL4A3 gene,laying a foundation for the study on the effect of miR-299 in the chondrogenic differentiation of stem cells by regulating the COL4A3 gene.Methods This study was made from March,2018 to December,2018.Firstly,the potential binding sites between miR-299 and COL4A3-3'UTR were pre dicted using bioinformatics.Then,the wild and mutant COL4A3-3'UTR sequences were amplified by PCR and cloned into psiCHECK-2 plasmid to construct corresponding recombinant vectors.The vectors were validated by enzyme digestion and gene sequencing.Finally,the cells were resuscitated,amplified,transfected and divided into 4 groups:COL4A3-WT+miR-299/NC group,COL4A3-WT+miR-299-inhibitor/NC-inhibitor group,COL4A3-MUT+miR-299/NC group and COL4A3-MUT+miR-299-inhibitor/NC-inhibitor group.Each group contains 3 holes,respectively.Luciferase activity in each group was determined using a dual-luciferase assay kit.The statistical analysis was conducted and differences between groups were compared by t test.Probabilities lower than 5％(P＜0.05) were considered statistically significant.Results Enzyme digestion and DNA sequencing showed that the dual-luciferase reporter gene vector of psiCHECK-2-COL4A3 was constructed successfully.Luciferase assay demonstrated that in wild COL4A3 gene,luciferase activity reduced in the miR-299 transfection group (The average R/F value was 59.38％) compared with the NC group (The average R/F value was 100.00％),with a statistical significant difference (P＜0.05).In wild COL4A3 gene treated with inhibitor,luciferase activity increased in the miR-299-inhibitor group (The average R/F value was 153.98％) compared with the NC-inhibitor group (The average R/F value was 100.00％),with a statistical significant difference (P＜0.05).In mutant COL4A3 gene treated with inhibitor,no obvious statistical differences in luciferase activity were found between miR-299 transfection group (The average R/F value was 102.09％),miR-299-inhibitor group (The average R/F value was 108.51％) and NC group (The average R/F value was 104.70％),NC-inhibitor group (The average R/F value was 105.13％) and/9＞0.05.Conclusion The dual-luciferase reporter gene vector of the 3'UTR of the COL4A3 gene is constructed successfully.In addition,dual-luciferase assay further verifies the authenticity of miR-299 directly targeting the 3'UTR of the COL4A3 gene.

BACKGROUND:m6A modification has been confirmed to play an important role in the occurrence and development of osteonecrosis of the femoral head;however,the role of m6A modification patterns in steroid-induced osteonecrosis of the femoral head remains unknown. OBJECTIVE:Bioinformatics analysis was performed based on the Gene Expression Omnibus(GEO)database to analyze the differential expression of the m6A gene in steroid-induced osteonecrosis of the femoral head,predict the downstream targeted miRNAs,and investigate the potential pathogenesis. METHODS:Expressing profiles of mRNA data of steroid-induced osteonecrosis of the femoral head were downloaded from GEO database(GSE123568).Differentially expressed genes(DEGs),Gene Ontology(GO)and Kyoto Encyclopedia of Genes and Genomes(KEGG)pathway enrichment analysis were performed using the R software.After obtaining these differentially methylated m6A genes(m6A-DEGs),we analyzed GO function and KEGG pathway enrichment and compared the correlation among the m6A-DEGs typing according to gene expression.The protein-protein interaction network and core gene subnetwork of m6A-DEGs were constructed using Cytoscape software.The m6A-DEGs-associated potential miRNAs were predicted using the TargetScan,miRTarBase,and miRBD databases.Simultaneously,ChIPBase and hTFtarget databases were used to predict potential transcription factors of seven core genes,then m6A-miRNA and transcription factor-m6A regulatory networks were constructed separately.Finally,the expression levels of the seven core m6A-DEGs were verified by using the GSE74089 dataset. RESULTS AND CONCLUSION:(1)A total of 2 460 common DEGs were screened out from datasets,among which 1 455 genes were upregulated and 1 005 genes were downregulated.(2)A total of 14 m6A-DEGs were identified in the datasets.Among them,11 m6A-DEGs were up-regulated and 3 m6A-DEGs were down-regulated.Differential gene expression was considered significant for m6A-DEGs in steroid-induced osteonecrosis of the femoral head(P<0.05).Spearman correlation analysis showed a significant correlation between m6A-DEGs.(3)GO and KEGG enrichment analysis showed that m6A-DEGs were mainly enriched in myeloid cell differentiation and development,immune and cytokine receptor activity,osteoclast differentiation,AMPK signaling pathway and interleukin-17 signaling pathway.(4)The seven core genes of m6A-DEGs contained YTHDF3,YTHDF1,YTHDF2,ALKBH5,METTL3,HNRNPA2B1,and HNRNPC.A total of 44 miRNAs overlapping were detected in the miRTarBase,miRDB,and TargetScan databases.Totally 79 transcription factors overlapping were found in the ChIPBase and hTFtarget databases.(5)The expression levels of six core m6A-DEGs in the GSE74089 dataset were consistent with those in the GSE123568 dataset.(6)These findings confirm that the seven m6A-DEGs identified through bioinformatics techniques play a regulatory role in the expression of various miRNAs,transcription factors,AMPK,and interleukin-17 signaling pathways,and these genes have a significant impact on the differentiation and development of bone marrow cells as well as osteoclast differentiation in steroid-induced osteonecrosis of the femoral head.Consequently,these findings offer data support and establish a research direction for future investigations into the pathogenesis and targeted therapeutic strategies for steroid-induced osteonecrosis of the femoral head.

Objective To investigate the potential of ginkgolide B(GB)in mitigating vascular endothelial injury by antagonizing endoplasmic reticulum stress(ERS)and elucidate its underlying molecular mechanism.Methods An injury model of human bone marrow-derived endothelial progenitor cells(EPCs)induced by tunica-mycin(TM)was established.Cell proliferation was assessed using MTS assay,while cell viability was determined through Calcein-AM/EthD-I double staining.Transwell assay was employed to evaluate cell migration ability.DCFH-DA staining was utilized to measure intracellular ROS levels,and NADPH activity was quantified via ELISA.JC-1 and DiOC6 staining were performed for qualitative and quantitative assessment of mitochondrial membrane potential respectively.Qrt-pcr analysis was conducted to determine mRNA expression levels,whereas western blot analysis enabled detection of protein expression levels in the cells.Results GB dose-dependently attenuated tunicamycin-induced ERS-mediated endothelial injury in hEPCs,as evidenced by decreased cell viability,impaired cell migration,and angiogenesis inhibition(P<0.01).Furthermore,GB treatment significantly reduced ROS production and NADPH levels within the cells(P<0.01),while also inhibiting ERS-mediated decline in mitochondrial membrane potential concentration-dependently(P<0.01).Additionally,GB inhibited the expression of ERS-related proteins such as GRP78,ATF4,CHOP etc.,regulated apoptosis-related protein Bcl-xl,Bax cleaved caspase-4 cytochrome c;thereby effectively counteracting endoplasmic reticulum stress-induced cellular damage.Conclusions GB exerts a protective effect on vascular endothelium by antagonizing endoplasmic reticulum stress;this mechanism may be attributed to its ability to reduce intracellular reactive oxygen species levels.It also suppresses the expression of ERS-related proteins(CHOP78 and ATF4),and modulates apoptosis-associated proteins(Bcl-xl,Bax,cleaved caspase-4,and cytochrome c).

Objective To explore the effectiveness of a PBL-CBL teaching model oriented towards competency evaluation after the introduction of standardized patients in orthopedic clinical internship teaching.Methods Eighty-nine medical students undergoing orthopedic internships at our hospital from 2022 to 2023 were divided into an S-PC teaching group and a PC teaching group.Based on Milestones 2.0,a competency evaluation model for orthopedic interns was established,including six primary in-dicators:patient care,clinical knowledge and skills,interpersonal communication,and more.After the course,students were as-sessed according to the established model.Results The S-PC group showed statistically significant differences in scores for pa-tient care,clinical knowledge and skills,interpersonal communication,system-based practice,and practice-based learning com-pared to the PC group(P＜0.05),with all scores in the S-PC group being higher than those in the PC group.Conclusion In-troducing standardized patients into the PBL-CBL teaching model in clinical education significantly enhances the competency of orthopedic interns.