Comparative analysis of codon usage patterns in the chloroplast genomes of nine forage legumes.

Leguminosae is one of the three largest families of angiosperms after Compositae and Orchidaceae. It is widely distributed and grows in a variety of environments, including plains, mountains, deserts, forests, grasslands, and even waters where almost all legumes can be found. It is one of the most important sources of starch, protein and oil in the food of mankind and also an important source of high-quality forage material for animals, which has important economic significance. In our study, the codon usage patterns and variation sources of the chloroplast genome of nine important forage legumes were systematically analyzed. Meanwhile, we also constructed a phylogenetic tree based on the whole chloroplast genomes and protein coding sequences of these nine forage legumes. Our results showed that the chloroplast genomes of nine forage legumes end with A/T bases, and seven identical high-frequency (HF) codons were detected among the nine forage legumes. ENC-GC3s mapping, PR2 analysis, and neutral analysis showed that the codon bias of nine forage legumes was influenced by many factors, among which natural selection was the main influencing factor. The codon usage frequency showed that the Nicotiana tabacum and Saccharomyces cerevisiae can be considered as receptors for the exogenous expression of chloroplast genes of these nine forage legumes. The phylogenetic relationships of the chloroplast genomes and protein coding genes were highly similar, and the nine forage legumes were divided into three major clades. Among the clades Melilotus officinalis was more closely related to Medicago sativa, and Galega officinalis was more closely related to Galega orientalis. This study provides a scientific basis for the molecular markers research, species identification and phylogenetic studies of forage legumes. Supplementary Information: The online version contains supplementary material available at 10.1007/s12298-024-01421-0.

Identification of Key Ubiquitination-Related Genes and Their Association with Immune Infiltration in Osteoarthritis Based on the mRNA-miRNA Network.

Osteoarthritis (OA) is a prevalent degenerative joint disease that is closely associated with functions of ubiquitination and immune cells, yet the mechanism remains ambiguous. This study aimed to find core ubiquitination-related genes and their correlative immune infiltration in OA using weighted gene co-expression network analysis (WGCNA). The ubiquitination-related genes, datasets GSE55235 and GSE143514 were obtained from open databases. WGCNA got used to investigate key co-expressed genes. Then, we screened differentially expressed miRNAs by "limma" package in R, and constructed mRNA-miRNA network. We conducted function enrichment analysis on the identified genes. CIBERSORT was then utilized to analyze the relevance between immune infiltration and genes. Lastly, RT-qPCR was further used to verify the prediction of bioinformatics. A sum of 144 ubiquitination-related genes in OA were acquired. Enrichment analysis indicated that obtained genes obviously involved in mTOR pathway to regulate the OA development. GRB2 and SEH1L and L-arginine synergistically regulate the mTOR signaling pathway in OA. Moreover, GRB2 and SEH1L were remarkably bound up with immune cell infiltration. Additionally, GRB2 expression was upregulated and SEH1L level was downregulated in the OA development by RT-qPCR experiment. The present study identified GRB2 and SEH1L as key ubiquitination-related genes which were involved in immune infiltration in OA patients, thereby providing new drug targets for OA.

Effect of In Situ NbC-Cr7C3@graphene/Fe Nanocomposite Inoculant Modification and Refinement on the Microstructure and Properties of W18Cr4V High-Speed Steel.

A novel graphene-coated nanocrystalline ceramic particle, iron-based composite inoculant was developed in this study to optimize the as-cast microstructure and mechanical properties of W18Cr4V high-speed steel (HSS). The effects of the composite inoculant on the microstructure, crystal structure, and mechanical properties of HSS were analyzed using transmission electron microscopy, scanning electron microscopy, energy dispersive spectroscopy, and X-ray diffraction. The (002-) and (020) crystal planes of the Fe3C and Cr7C3 phases, respectively, were collinear at two points in the reciprocal space, indicating a coherent relationship between the Fe3C and Cr7C3 phases in the tempered modified HSS. This contributed to an improved non-uniform nucleation rate and refining of the HSS grains. The mechanical properties of the modified steel exhibited a general improvement. Specifically, the modification treatment enhanced the hardness of HSS from HRC 63.2 to 66.4 and the impact toughness by 48.3%.

A tungsten phosphide cocatalyst enhanced bismuth tungstate photoanode with the robust built-in electric field towards highly efficient photoelectrochemical water splitting.

The use of low-cost and effective cocatalyst is a potential strategy to optimize the effectiveness of photoelectrochemical (PEC) water splitting. In this study, tungsten phosphide (WP) is introduced as a remarkably active cocatalyst to enhance the PEC efficiency of a Bi2WO6 photoanode. The onset potential of Bi2WO6/WP demonstrates a negative shift, while the photocurrent density demonstrates a significant 5.5-fold increase compared to that of unmodified Bi2WO6 at 1.23 VRHE (reversible hydrogen electrode). The loading of WP cocatalyst facilitates the rapid transfer of holes, increasing the range of visible light absorption, the water adsorption ability as well as promoting the separation of photogenerated electrons and holes via the built-in electric field between Bi2WO6 and WP. This study proposes a strategy to hinder the recombination of electron-hole pairs by using WP cocatalyst as a hole capture agent, improve the photoelectric conversion efficiency, and enhance the overall photoelectrochemical properties of Bi2WO6 photoanode.

Knockdown of angiopoietin-like 4 suppresses sepsis-induced acute lung injury by blocking the NF-κB pathway activation and hindering macrophage M1 polarization and pyroptosis.

OBJECTIVE: Sepsis-induced acute lung injury (ALI) is a life-threatening disease. Macrophage pyroptosis has been reported to exert function in ALI. We aimed to investigate the mechanisms of ANGPTL4-mediated cell pyroptosis in sepsis-induced ALI, thus providing new insights into the pathogenesis and prevention and treatment measures of sepsis-induced ALI. METHODS: In vivo animal models and in vitro cell models were established by cecal ligation and puncture (CLP) method and lipopolysaccharide-induced macrophages RAW264.7. ANGPTL4 was silenced in CLP mice or macrophages, followed by the determination of ANGPTL4 expression in bronchoalveolar lavage fluid (BALF) or macrophages. Lung histopathology was observed by H&E staining, with pathological injury scores evaluated and lung wet and dry weight ratio recorded. M1/M2 macrophage marker levels (iNOS/CD86/Arg1), inflammatory factor (TNF-α/IL-6/IL-1ß/iNOS) expression in BALF, cell death and pyroptosis, NLRP3 inflammasome, cell pyroptosis-related protein (NLRP3/Cleaved-caspase-1/caspase-1/GSDMD-N) levels, NF-κB pathway activation were assessed by RT-qPCR/ELISA/flow cytometry/Western blot, respectively. RESULTS: ANGPTL4 was highly expressed in mice with sepsis-induced ALI, and ANGPTL4 silencing ameliorated sepsis-induced ALI in mice. In vivo, ANGPTL4 silencing repressed M1 macrophage polarization and macrophage pyroptosis in mice with sepsis-induced ALI. In vitro, ANGPTL4 knockout impeded LPS-induced activation and pyroptosis of M1 macrophages and hindered LPS-induced activation of the NF-κB pathway in macrophages. CONCLUSION: Knockdown of ANGPTL4 blocks the NF-κB pathway activation, hinders macrophage M1 polarization and pyroptosis, thereby suppressing sepsis-induced ALI.

A Study on the Psychological Experience and Influential Factors of Pregnant Women Who Decided Elective Caesarean Section After Public Health Emergencies - A Cross-Sectional Survey.

Background: The COVID-19 pandemic used to be a major public health emergency which affected people worldwide, and it affected individuals' body, mood, work and lifestyle to some extent. The pregnant woman affected by the unstable hormone will be more sensitive than normal ones. Long-term depression and anxiety could feedback on their body and lead to a host of pregnancy complications. Because pregnant women who choose cesarean section are awake during the perioperative period, to ensure safety, the degree of cooperation about psychology and behavior is relatively high, so we should know the psychological state of such a group of people. Objective: This study aims to explore psychological experience and influential factors of pregnant women who decided elective caesarean section after the COVID-19 pandemic. Methods: This is a cross-sectional study carried out in a hospital in Shanghai, according to the inclusion and exclusion criteria, we selected pregnant women who selected elective cesarean section as the study objects, all participants provided informed consent and completed questionnaires, including sociodemographic questionnaire, Generalized Anxiety Disorder scale (GAD-7) and General Well-Being Schedule (GWBS). Software SPSS 23.0 was used to analyze and explore the influencing factors. Results: Eligible 595 questionnaires were included in the study, the mean score of GAD-7 was 4.855 ± 3.254 and 90.699 ± 13.807 of GWBS. Generalized linear regression analysis revealed several factors that were statistically significant with the two scales, including birthplace, average monthly income, number of abortion and pregnancy complication (p < 0.01). Conclusion: The COVID-19 infection status and symptoms around infection have no statistical difference in anxiety level and general well-being after they experience the COVID-19 pandemic. However, through this study, we found some influencing factors that worth further exploration. In the future, we will expand the sample size to explore the different situation of multi-center, and we hope provide psychological nursing interventions based on existing results to offer a better delivery experience.

Interaction of air pollution and meteorological factors on IVF outcomes: A multicenter study in China.

BACKGROUND: Previous studies revealed associations between air-pollutant exposure and in vitro fertilization (IVF) outcomes. However, modification effects of air pollution on IVF outcomes by meteorological conditions remain elusive. METHODS: This multicenter retrospective cohort study included 15,217 women from five northern Chinese cities during 2015-2020. Daily average concentrations of air pollutants (PM2.5, PM10, O3, NO2, SO2, and CO) and meteorological factors (temperature, relative humidity, wind speed, and sunshine duration) during different exposure windows were calculated as individual approximate exposure. Generalized estimating equations models and stratified analyses were conducted to assess the associations of air pollution and meteorological conditions with IVF outcomes and estimate potential interactions. RESULTS: Positive associations of wind speed and sunshine duration with pregnancy outcomes were detected. In addition, we observed that embryo transfer in spring and summer had a higher likelihood to achieve a live birth compared with winter. Exposure to PM2.5, SO2, and O3 was adversely correlated with pregnancy outcomes in fresh IVF cycles, and the associations were modified by air temperature, relative humidity, and wind speed. The inverse associations of PM2.5 and SO2 exposure with biochemical pregnancy were stronger at lower temperatures and humidity. Negative associations of PM2.5 with clinical pregnancy were only significant at lower temperatures and wind speeds. Moreover, the effects of O3 on live birth were enhanced by higher wind speed. CONCLUSIONS: Our results suggested that the associations between air-pollutant exposure and IVF outcomes were modified by meteorological conditions, especially temperature and wind speed. Women undergoing IVF treatment should be advised to reduce outdoor time when the air quality was poor, particularly at lower temperatures.

EZH2 controls epicardial cell migration during heart development.

Enhancer of zeste homolog 2 (EZH2) is an important transcriptional regulator in development that catalyzes H3K27me3. The role of EZH2 in epicardial development is still unknown. In this study, we show that EZH2 is expressed in epicardial cells during both human and mouse heart development. Ezh2 epicardial deletion resulted in impaired epicardial cell migration, myocardial hypoplasia, and defective coronary plexus development, leading to embryonic lethality. By using RNA sequencing, we identified that EZH2 controls the transcription of tissue inhibitor of metalloproteinase 3 (TIMP3) in epicardial cells during heart development. Loss-of-function studies revealed that EZH2 promotes epicardial cell migration by suppressing TIMP3 expression. We also found that epicardial Ezh2 deficiency-induced TIMP3 up-regulation leads to extracellular matrix reconstruction in the embryonic myocardium by mass spectrometry. In conclusion, our results demonstrate that EZH2 is required for epicardial cell migration because it blocks Timp3 transcription, which is vital for heart development. Our study provides new insight into the function of EZH2 in cell migration and epicardial development.

The longevity protein p66Shc is required for neonatal heart regeneration.

The longevity protein p66Shc is essential for the senescence signaling that is involved in heart regeneration and remodeling. However, the exact role of p66Shc in heart regeneration is unknown. In this study, we found that p66Shc deficiency decreased neonatal mouse cardiomyocyte (CM) proliferation and impeded neonatal heart regeneration after apical resection injury. RNA sequencing and functional verification demonstrated that p66Shc regulated CM proliferation by activating ß-catenin signaling. These findings reveal the critical role of p66Shc in neonatal heart regeneration and provide new insights into senescence signaling in heart regeneration.

Effects of the genetic knockout of the ß-1,3-galactosyltransferase 2 on spatial learning and neurons in the adult mouse hippocampus and somatosensory cortex.

OBJECTIVE: Glycosyltransferases contribute to the biosynthesis of glycoproteins, proteoglycans and glycolipids and play essential roles in various processes in the brain, such as learning and memory, brain development, neuronal survival and neurodegeneration. ß-1,3-galactosyltransferase 2 (B3galt2) belongs to the ß-1,3-galactosyltransferase gene family and is highly expressed in the brain. Recent studies have indicated that B3galt2 plays a vital role in ischemic stroke through several signaling pathways in a mouse model. However, the function of B3galt2 in the brain remains poorly understood. METHODS: The genotypes of mice were determined by PCR. To verify B3galt2 expression in an adult mouse brain, X-gal staining was performed in 6-month-old B3galt2 heterozygous (B3galt2+/-) mice. Using adult B3galt2 homozygous (B3galt2-/-), heterozygous and wild-type (WT) littermates, spatial learning and memory were determined by the Morris Water Maze test, and neurotoxicity and synaptic plasticity were examined by immunofluorescence. RESULTS: B3galt2 was highly expressed in the adult mouse hippocampus and cortex, especially in the hippocampal dentate gyrus. Compared to that of WT mice, the spatial learning ability of adult B3galt2-/- mice was impaired. B3galt2 mutations also caused neuronal loss and synaptic dysfunction in the hippocampus and somatosensory cortex, and these changes were more obvious in B3galt2-/- mice than in B3galt2+/- mice. CONCLUSIONS: The findings indicate that B3galt2 plays an important role in cognitive function, neuronal maintenance and synaptic plasticity in the adult mouse brain. This study suggests that genetic and/or pharmacological manipulation of glycosyltransferases may be a novel strategy for elucidating the mechanism of and managing various brain disorders.

Boosted charge transfer in ReS2/Nb2O5 heterostructure by dual-electric field: Toward superior electrochemical reversibility for lithium-ion storage.

Heterostructures with the electric field effect can excite the charge transfer kinetics of materials due to the driving force of the electric field. Herein, we report a new ReS2/Nb2O5 heterostructure of rhenium disulfide coupled to niobium oxide with a mutually compatible band structure and enriched oxygen vacancies. The unique heterostructure can facilitate the redistribution of charges to induce built-in electric fields and microlocalized electric fields. As expected, the ReS2/Nb2O5 heterostructure shows a superior lithium-ion reversible capacity of 805 mAh g-1 after 2400 h at 0.10 A g-1, and 414 mAh g-1 at 2.00 A g-1. In addition, in situ X-ray diffraction and ex situ X-ray photoelectron spectroscopy analysis reveal the phase transition process of the ReS2/Nb2O5 heterostructure during the electrochemical reaction. This provides deeper insights into the construction of high-performance lithium-ion storage materials based on heterostructures with dual-electric field-driven charge transfer.

A DFT prediction of two-dimensional MB3 (M = V, Nb, and Ta) monolayers as excellent anode materials for lithium-ion batteries.

Transition metal borides (MBenes) have recently drawn great attention due to their excellent electrochemical performance as anode materials for lithium-ion batteries (LIBs). Using the structural search code and first-principles calculations, we identify a group of the MB3 monolayers (M = V, Nb and Ta) consisting of multiple MB4 units interpenetrating with each other. The MB3 monolayers with non-chemically active surfaces are stable and have metal-like conduction. As the anode materials for Li-ion storage, the low diffusion barrier, high theoretical capacity, and suitable average open circuit voltage indicate that the MB3 monolayers have excellent electrochemical performance, due to the B3 chain exposed on the surface improving the Li atoms' direct adsorption. In addition, the adsorbed Li-ions are in an ordered hierarchical arrangement and the substrate structure remains intact at room temperature, which ensures excellent cycling performance. This work provides a novel idea for designing high-performance anode materials for LIBs.

Triflumizole Induces Developmental Toxicity, Liver Damage, Oxidative Stress, Heat Shock Response, Inflammation, and Lipid Synthesis in Zebrafish.

Triflumizole (TFZ) toxicity must be investigated in the aquatic environment to understand the potential risks to aquatic species. Accordingly, the adverse effects of TFZ exposure in zebrafish were investigated. Results demonstrate that, after TFZ exposure, the lethal concentration 50 (LC50) in 3 d post-fertilization (dpf) embryos and 6 dpf larvae were 4.872 and 2.580 mg/L, respectively. The development (including pericardium edema, yolk sac retention, and liver degeneration) was apparently affected in 3 dpf embryos. Furthermore, the alanine aminotransferase (ALT) activity, superoxide dismutase (SOD) activity, catalase (CAT) activity, and malondialdehyde (MDA) content in 6 dpf larvae were significantly increased. Additionally, the expression of heat shock response genes (including hsp70, grp78, hsp90, and grp94), inflammatory genes (including p65-nfκb, il-1ß, and cox2a), and lipid synthetic genes (including srebp1, fas, acc, and ppar-γ) in 3 dpf embryos was significantly increased, which was also partially observed in the intestinal cell line form Pampus argenteus. Taken together, TFZ could affect the development of zebrafish, accompanied by disturbances of oxidative stress, heat shock response, inflammation, and lipid synthesis. Our findings provide an original insight into the potential risks of TFZ to the aquatic ecosystem.

Contractility detection of isolated mouse papillary muscle using myotronic Myostation-Intact device.

BACKGROUND: To understand the relationship between myocardial contractility and external stimuli, detecting ex vivo myocardial contractility is necessary. METHODS: We elaborated a method for contractility detection of isolated C57 mouse papillary muscle using Myostation-Intact system under different frequencies, voltages, and calcium concentrations. RESULTS: The results indicated that the basal contractility of the papillary muscle was 0.27 ± 0.03 mN at 10 V, 500-ms pulse duration, and 1 Hz. From 0.1 to 1.0 Hz, contractility decreased with an increase in frequency (0.45 ± 0.11-0.10 ± 0.02 mN). The voltage-initiated muscle contractility varied from 3 to 6 V, and the contractility gradually increased as the voltage increased from 6 to 10 V (0.14 ± 0.02-0.28 ± 0.03 mN). Moreover, the muscle contractility increased when the calcium concentration was increased from 1.5 to 3 mM (0.45 ± 0.17-1.11 ± 0.05 mN); however, the contractility stopped increasing even when the concentration was increased to 7.5 mM (1.02 ± 0.23 mN). CONCLUSIONS: Our method guaranteed the survivability of papillary muscle ex vivo and provided instructions for Myostation-Intact users for isolated muscle contractility investigations.

An Outbreak of Severe Neonatal Pneumonia Caused by Human Respiratory Syncytial Virus BA9 in a Postpartum Care Centre in Shenyang, China.

Human respiratory syncytial virus (HRSV) is a major pathogen of lower respiratory tract infections in children (<5 years) and older individuals, with outbreaks mainly reported among infants in hospital pediatric departments and intensive care units (ICUs). An outbreak of severe neonatal pneumonia occurred in a postpartum center in Shenyang city, China, from January to February 2021. In total, 34 respiratory samples were collected from 21 neonates and 13 nursing staff. The samples were screened for 27 pathogens using a TaqMan low-density array, and 20 samples tested positive for HRSV, including 16 neonates and 4 nursing staff samples. Among the 16 hospitalized neonates, seven were admitted to an ICU and nine to general wards. Four of the nursing staff had asymptomatic infections. To investigate the genetic characteristics of the HRSV responsible for this outbreak, the second hypervariable region (HVR2) sequences of the G gene were obtained from six neonates and two nursing staff. Phylogenetic analyses revealed that all eight sequences (SY strains) were identical, belonging to the HRSV BA9 genotype. Our findings highlight the necessity for strict hygiene and disease control measures so as to prevent cross-infection and further avoid potential outbreaks of severe infectious respiratory diseases. IMPORTANCE Human respiratory syncytial virus (HRSV) is one of the leading causes of acute lower respiratory infections (ALRI) worldwide. In this study, we first reported an outbreak of severe neonatal pneumonia caused by HRSVB BA9 at a postpartum care center in mainland China. Among 20 confirmed cases, 16 were hospitalized neonates with 7 in the ICU ward, and the other four were nursing staff with asymptomatic infections. Our findings highlighted the importance of preventing cross-infection in such postpartum centers.

Poor ovarian response is associated with air pollutants: A multicentre study in China.

BACKGROUND: Human evidence on the association between air pollution and ovarian response is scarce. Poor ovarian response (POR) with an incidence of 5-35% is a tricky problem in IVF treatment. METHODS: In this large-scale multicentre study, we included 2186 women with POR (< 4 oocytes retrieved) and 7033 women with a normal ovarian response (10-15 oocytes retrieved), who underwent their first in vitro fertilization treatment in five cities in northern China during 2015-2020. Average concentrations of six air pollutants (PM2.5, PM10, O3, NO2, CO, and SO2) during different exposure windows (5 days, 1, 3, 6, and 12 months) before oocyte pick up (OPU) were calculated using data from the air monitoring station nearest to the residential site as approximate individual exposure. Logistic regression models were employed to assess the association between exposure to air pollutants and the risk of POR. Stratification analyses were conducted based on female age. Sensitivity analyses were performed in poor responders identified by Bologna criteria and women with unexpected POR. FINDINGS: We detected that increased SO2 exposure during all exposure windows before OPU was associated with a higher risk of POR, especially for women ≤ 30 years old. In the stratified analysis, the effect sizes were larger for the unexpected poor ovarian response. INTERPRETATION: The findings provide human evidence for adverse effects of exposure to ambient air pollutants on ovarian response and underscore the need to reduce ambient air pollution exposure in women of reproductive age to protect human fertility. FUNDING: This study was granted from the National Key Research and Development Program (2018YFC1004203), the Major Special Construction Plan for Discipline Construction Project of China Medical University (3110118033), the Shengjing Freelance Researcher Plan of Shengjing Hospital of China Medical University, and the National Natural Science Foundation of China (82071601), the Central Government Special Fund for Local Science and Technology Development (2020JH6/10500006).

Exploration of the Visual Function after the Implantation of Continuous Visual Range Human Cocrystal Micromonocular Vision in Both Eyes of the Patient.

Eye diseases such as myopia, hyperopia, astigmatism, and cataract are have affected most people at home and abroad for many years. With the development of science and technology, people who wear glasses are now younger, and they are on the rise over time. This paper is to explore the visual function after the implantation of continuous visual range human cocrystal micromonocular vision in both eyes of the patient. On this basis, the latest visual sensor technology is used to conduct clinical research on the operation, a case-control study is performed on the patient's eyes, followed by intraocular lens insertion surgery, one eye is hemitrope and the other eye has a certain degree of intraocular lens inserted, and it is recorded within a period of time after the operation. According to the analysis of the experimental results, the patient's naked eye and corrected distance vision is (t = 2.102, P = 0.049), middle distance vision (t = 1.403, P = 0.200), and near vision (t = 1.463, P = 0.216). After the operation, the ratio of patients taking off glasses 91.8%. After the continuous visual range intraocular lens micromonocular vision design, it can well correct the patient's near and far vision of the naked eye of both eyes.

Proteogenomics Integrating Reveal a Complex Network, Alternative Splicing, Hub Genes Regulating Heart Maturation.

Heart maturation is an essentially biological process for neonatal heart transition to adult heart, thus illustrating the mechanism of heart maturation may be helpful to explore postnatal heart development and cardiac cardiomyopathy. This study combined proteomic analysis based on isobaric tags for relative and absolute quantitation (iTRAQ) and transcriptome analysis based on RNA sequencing to detect the proteins and genes associated with heart maturation in mice. The proteogenomics integrating analysis identified 254 genes/proteins as commonly differentially expressed between neonatal and adult hearts. Functional and pathway analysis demonstrated that these identified genes/proteins contribute to heart maturation mainly by regulating mRNA processing and energy metabolism. Genome-wide alternative splicing (AS) analysis showed that some important sarcomere and energy-associated genes undergo different AS events. Through the Cytoscape plug-in CytoHubba, a total of 23 hub genes were found and further confirmed by RT-qPCR. Next, we verified that the most up-regulated hub gene, Ogdhl, plays an essential role in heart maturation by detecting energy metabolism phenotype changes in the Ogdhl-interfering cardiomyocytes. Together, we revealed a complex gene network, AS genes and patterns, and candidate hub genes controlling heart maturation by proteome and transcriptome combination analysis.

miR-302a-3p suppresses melanoma cell progression via targeting METTL3.

The miRNA-302 family plays a critical role in carcinogenesis. As an enzyme that regulates the N6-methyladenosine modification, methyltransferase-like 3 (METTL3) plays important roles in the development and progression of various tumours. However, the upstream regulatory mechanisms of METTL3 in melanoma have not yet been fully investigated. Herein, we investigated the functions of miR-302a-3p and its target RNA METTL3 on proliferation, apoptosis, and invasion of melanoma. Quantitative real-time PCR and immunofluorescence staining were used to measure the expression of METTL3 mRNA and protein level after transfection. miR-302a-3p expression was determined by quantitative reverse transcription-PCR. The cell proliferation, cell cycle progression, apoptosis, colony formation, migration, and cell invasion ability were determined using MTT assay, propidium iodide (PI) staining, Annexin V/PI flow cytometry, plate clone assay, and Transwell migration and invasion assays, respectively. Melanoma cell metastasis was also evaluated using an in vivo model. The effect of METTL3 on the phosphorylation of PI3K and AKT was measured with western blot analysis. Our results showed that miR-302a-3p was significantly downregulated in melanoma and exerted a tumour suppressive role against melanoma progression. We identified METTL3 as a direct target of miR-302a-3p in melanoma cells using bioinformatics analysis and luciferase assay. Furthermore, the enforced overexpression of METTL3 promoted the proliferation, cell cycle progression, cell invasion, migration, expression of epithelial-to-mesenchymal transition markers, and the PI3K-AKT signalling pathway as well as suppressed the apoptosis of melanoma cells. Meanwhile, silencing the expression of METTL3 with specific shRNA demonstrated reverse outcomes of the above phenotypes in melanoma cells. By rescue experiments, we found that the restoration of METTL3 expression in miR-302a-3p-overexpressing melanoma cells successfully recovered the miR-302a-3p-mediated melanoma suppression. The in vivo results also showed that miR-302a-3p substantially inhibited melanoma cell growth and metastasis. In summary, this study demonstrated that miR-302a-3p targets METTL3 and plays tumour suppressive roles in the proliferation, apoptosis, invasion, and migration of melanoma cells.