Ecotoxicological effects of polyethylene microplastics and lead (Pb) on the biomass, activity, and community diversity of soil microbes.

Microplastics and heavy metals are ubiquitous and persistent contaminants that are widely distributed worldwide, yet little is known about the effects of their interaction on soil ecosystems. A soil incubation experiment was conducted to investigate the individual and combined effects of polyethylene microplastics (PE-MPs) and lead (Pb) on soil enzymatic activities, microbial biomass, respiration rate, and community diversity. The results indicate that the presence of PE-MPs notably reduced soil pH and elevated soil Pb bioavailability, potentially exacerbated the combined toxicity on the biogeochemical cycles of soil nutrients, microbial biomass carbon and nitrogen, and the activities of soil urease, sucrase, and alkaline phosphatase. Soil CO2 emissions increased by 7.9% with PE-MPs alone, decreased by 46.3% with single Pb, and reduced by 69.4% with PE-MPs and Pb co-exposure, compared to uncontaminated soils. Specifically, the presence of PE-MPs and Pb, individually and in combination, facilitated the soil metabolic quotient, leading to reduced microbial metabolic efficiency. Moreover, the addition of Pb and PE-MPs modified the composition of the microbial community, leading to the enrichment of specific taxa. Tax4Fun analysis showed the effects of Pb, PE-MPs and their combination on the biogeochemical processes and ecological functions of microbes were mainly by altering amino acid metabolism, carbohydrate metabolism, membrane transport, and signal transduction. These findings offer valuable insights into the ecotoxicological effects of combined PE-MPs and Pb on soil microbial dynamics, reveals key assembly mechanisms and environmental drivers, and highlights the potential threat of MPs and heavy metals to the multifunctionality of soil ecosystems.

Metabolomics combined with physiology and transcriptomics reveal how Nicotiana tabacum leaves respond to cold stress.

Low temperature-induced cold stress is a major threat to plant growth, development and distribution. Unraveling the responses of temperature-sensitive crops to cold stress and the mechanisms of cold acclimation are critical for food demand. In this study, combined physiological, transcriptomic, and metabolomic analyses were conducted on Nicotiana tabacum suffering short-term 4 °C cold stress. Our results showed that cold stress destroyed cellular membrane stability, decreased the chlorophyll (Chl) and carotenoid contents, and closed stomata, resulting in lipid peroxidation and photosynthesis restriction. Chl fluorescence measurements revealed that primary photochemistry, photoelectrochemical quenching and photosynthetic electron transport in Nicotiana tabacum leaves were seriously suppressed upon exposer to cold stress. Enzymatic and nonenzymatic antioxidants, including superoxide dismutase, catalase, peroxidase, reduced glutathione, proline, and soluble sugar, were all profoundly increased to trigger the cold acclimation defense against oxidative damage. A total of 178 metabolites and 16,204 genes were differentially expressed in cold-stressed Nicotiana tabacum leaves. MEturquoise and MEblue modules identified by WGCNA were highly correlated with physiological indices, and the corresponding hub genes were significantly enriched in pathways related to photosynthesis - antenna proteins and flavonoid biosynthesis. Untargeted metabolomic analysis identified specific metabolites, including sucrose, phenylalanine, glutamine, glutamate, and proline, that enhance plant cold acclimation. Combined transcriptomics and metabolomic analysis highlight the vital roles of carbohydrate and amino acid metabolism in enhancing the cold tolerance of Nicotiana tabacum. Our comprehensive investigation provides novel insights for efforts to alleviate low temperature-induced oxidative damage to Nicotiana tabacum plants and proposes a breeding target for cold stress-tolerant cultivars.

Bioinformatic analysis of defective viral genomes in SARS-CoV-2 and its impact on population infection characteristics.

DVGs (Defective Viral Genomes) are prevalent in RNA virus infections. In this investigation, we conducted an analysis of high-throughput sequencing data and observed widespread presence of DVGs in SARS-CoV-2. Comparative analysis between SARS-CoV-2 and diverse DNA viruses revealed heightened susceptibility to damage and increased sequencing sample heterogeneity within the SARS-CoV-2 genome. Whole-genome sequencing depth variability analysis exhibited a higher coefficient of variation for SARS-CoV-2, while DVG analysis indicated a significant proportion of recombination sites, signifying notable genome heterogeneity and suggesting that a large proportion of assembled virus particles contain incomplete RNA sequences. Moreover, our investigation explored the sequencing depth and DVG content differences among various strains. Our findings revealed that as the virus evolves, there is a notable increase in the proportion of intact genomes within virus particles, as evidenced by third-generation sequencing data. Specifically, the proportion of intact genome in the Omicron strain surpassed that of the Delta and Alpha strains. This observation effectively elucidates the heightened infectiousness of the Omicron strain compared to the Delta and Alpha strains. We also postulate that this improvement in completeness stems from enhanced virus assembly capacity, as the Omicron strain can promptly facilitate the binding of RNA and capsid protein, thereby reducing the exposure time of vulnerable virus RNA in the host environment and significantly mitigating its degradation. Finally, employing mathematical modeling, we simulated the impact of DVG effects under varying environmental factors on infection characteristics and population evolution. Our findings provide an explanation for the close association between symptom severity and the extent of virus invasion, as well as the substantial disparity in population infection characteristics caused by the same strain under distinct environmental conditions. This study presents a novel approach for future virus research and vaccine development.

The Mathematical Modeling of the Host-Virus Interaction in Dengue Virus Infection: A Quantitative Study.

Infectious diseases, such as Dengue fever, pose a significant public health threat. Developing a reliable mathematical model plays a crucial role in quantitatively elucidating the kinetic characteristics of antibody-virus interactions. By integrating previous models and incorporating the antibody dynamic theory, we have constructed a novel and robust model that can accurately simulate the dynamics of antibodies and viruses based on a comprehensive understanding of immunology principles. It explicitly formulates the viral clearance effect of antibodies, along with the positive feedback stimulation of virus-antibody complexes on antibody regeneration. In addition to providing quantitative insights into the dynamics of antibodies and viruses, the model exhibits a high degree of accuracy in capturing the kinetics of viruses and antibodies in Dengue fever patients. This model offers a valuable solution to modeling the differences between primary and secondary Dengue infections concerning IgM/IgG antibodies. Furthermore, it demonstrates that a faster removal rate of antibody-virus complexes might lead to a higher peak viral loading and worse clinical symptom. Moreover, it provides a reasonable explanation for the antibody-dependent enhancement of heterogeneous Dengue infections. Ultimately, this model serves as a foundation for constructing an optimal mathematical model to combat various infectious diseases in the future.

EVLncRNAs 3.0: an updated comprehensive database for manually curated functional long non-coding RNAs validated by low-throughput experiments.

Long noncoding RNAs (lncRNAs) have emerged as crucial regulators across diverse biological processes and diseases. While high-throughput sequencing has enabled lncRNA discovery, functional characterization remains limited. The EVLncRNAs database is the first and exclusive repository for all experimentally validated functional lncRNAs from various species. After previous releases in 2018 and 2021, this update marks a major expansion through exhaustive manual curation of nearly 25 000 publications from 15 May 2020, to 15 May 2023. It incorporates substantial growth across all categories: a 154% increase in functional lncRNAs, 160% in associated diseases, 186% in lncRNA-disease associations, 235% in interactions, 138% in structures, 234% in circular RNAs, 235% in resistant lncRNAs and 4724% in exosomal lncRNAs. More importantly, it incorporated additional information include functional classifications, detailed interaction pathways, homologous lncRNAs, lncRNA locations, COVID-19, phase-separation and organoid-related lncRNAs. The web interface was substantially improved for browsing, visualization, and searching. ChatGPT was tested for information extraction and functional overview with its limitation noted. EVLncRNAs 3.0 represents the most extensive curated resource of experimentally validated functional lncRNAs and will serve as an indispensable platform for unravelling emerging lncRNA functions. The updated database is freely available at https://www.sdklab-biophysics-dzu.net/EVLncRNAs3/.

More or less deadly? A mathematical model that predicts SARS-CoV-2 evolutionary direction.

SARS-CoV-2 has caused tremendous deaths globally. It is of great value to predict the evolutionary direction of SARS-CoV-2. In this paper, we proposed a novel mathematical model that could predict the evolutionary trend of SARS-CoV-2. We focus on the mutational effects on viral assembly capacity. A robust coarse-grained mathematical model is constructed to simulate the virus dynamics in the host body. Both virulence and transmissibility can be quantified in this model. A delicate equilibrium point that optimizes the transmissibility can be numerically obtained. Based on this model, the virulence of SARS-CoV-2 might further decrease, accompanied by an enhancement of transmissibility. However, this trend is not continuous; its virulence will not disappear but remains at a relatively stable range. A virus assembly model which simulates the virus packing process is also proposed. It can be explained why a few mutations would lead to a significant divergence in clinical performance, both in the overall particle formation quantity and virulence. This research provides a novel mathematical attempt to elucidate the evolutionary driving force in RNA virus evolution.

OsWHY1 Interacts with OsTRX z and is Essential for Early Chloroplast Development in Rice.

WHIRLY (WHY) family proteins, a small family of single-stranded DNA (ssDNA) binding proteins, are widely found in plants and have multiple functions to regulate plant growth and development. However, WHY in rice has received less attention. In this study, we continued our previous study on OsTRX z that is important for chloroplast development. OsTRX z was discovered to interact with OsWHY1, which was confirmed using yeast two-hybrid, pull-down, and BiFC assays. Subsequently, the oswhy1 mutants were obtained by CRISPR/Cas9, which exhibited an albino phenotype and died after the three-leaf stage. Consistent with this albino phenotype, low amounts of Chl a, Chl b, and Car were detected in the oswhy1-1 mutant. Moreover, the oswhy1-1 mutant had chloroplasts with disrupted architecture and no stacked grana and thylakoid membranes. Subcellular localization showed that the OsWHY1-GFP fusion protein was targeted to the chloroplast. What's more, OsWHY1 was found to be preferentially expressed in young leaves and was involved in chloroplast RNA editing and splicing. Mutation of OsWHY1 significantly affected the expression of chloroplast and ribosome development-related and chlorophyll synthesis-related genes. In conclusion, OsWHY1 contributes to early chloroplast development and normal seedling survival in rice. These results will further elucidate the molecular mechanism of chloroplast development and expand our understanding of WHY1 functions.

A Chewing Gum Residue-Based Gel with Superior Mechanical Properties and Self-Healability for Flexible Wearable Sensor.

Chewing gum residue is hard to decompose and easy to cause pollution, which is highly desirable to realize recycling. In this paper, a chewing gum gel with enhanced mechanical properties and self-healing properties is prepared by using polyvinyl alcohol (PVA) as the backbone in chewing gum residue. The hydrogen bond and the borax ester bond are employed to construct reversible interaction to enhance the self-healing ability. The physical crosslinking is realized by further freeze-thaw treatment to improve its mechanical properties. The gel demonstrates high elongation at break of 610% and strength of 0.11 MPa, as well as excellent self-healing performance and recyclable properties. In particular, the gel with a fast signal response is successfully applied as a wearable strain sensor to monitor different types of human motion. The gel as a sensor exhibits self-healing properties suggesting superior safety and stability, and displays wide linear sensitivity (the gauge factor is 0.417 and 0.170). The gel can be further served to explore temperature changes, implying the application in temperature monitoring. This study develops a novel approach for the recycle and reuse of chewing gum residue. The obtained gel may be a promising candidate for the fabrication of flexible wearable sensor.

Identification of prognostic signature with seven LncRNAs for papillary thyroid carcinoma.

PURPOSE: With the increasing incidence of thyroid cancer (TC), the prognostic risk assessment of thyroid cancer has been becoming more and more important. The aim of this study was to screen TC-related biomarkers and identify key multi-long non coding RNA (lncRNA) signature for prognostic risk assessment of papillary TC. MATERIAL AND METHODS: The lncRNAs differentially expressed between TC tissue and adjacent normal tissue was identified by R language. Bioinformatics analysis was applied to screen the lncRNAs significantly associated with prognosis in TC patients and build the multi-lncRNA signature. The lncRNAs were annotated by co-expression and enrichment analysis to demonstrate the underlying mechanism of their effect on prognosis. RESULTS: 285 up-regulated and 174 down-regulated differently expressed lncRNAs were identified. Based on seven signature lncRNAs (AL591846.2, AC253536.3, AC004112.1, LINC00900, AC008555.1, TNRC6C-AS1, LINC01736) a prognostic risk assessment model was built. The model can segregate the patients into the high-risk and low-risk groups (P value <0.0001, CI: 0.02∼0.14). ROC analysis revealed that the area under the curve reached 0.86, indicating that this model had an excellent sensitivity and specificity. Also, the model could act as an independent prognostic indication (HR â€‹= â€‹2.90, P value â€‹= â€‹0.0094 with multivariate analysis). Annotation results further supported and enriched our understanding of the seven signature lncRNAs. Importantly, expression levels of three of the seven lncRNAs were confirmed in Gene Expression Omnibus (GEO) data. CONCLUSIONS: This study has provided a promising method for the prognostic risk assessment in patients with TC.

The effect of long-term cold acclimation on redox state and antioxidant defense in the high-altitude frog, Nanorana pleskei.

Cold hardiness is a key determinant of the distribution and abundance of ectothermic animals, and thermal acclimation can strongly influence stress tolerance phenotypes. However, the effect of cold acclimation on oxidative stress and antioxidant defenses is still not well understood. Here, we investigated the effects of long-term cold exposure (30 days at 4 °C in darkness versus 30 days at 20 °C in natural light) on the redox state and antioxidant defenses of the high-altitude frog, Nanorana pleskei, indigenous to the Tibetan plateau. We found that cold acclimation, under conditions mimicking winter, led to a significant increase in the ratio of oxidized glutathione (GSSG) to its reduced form (GSH) in liver and skeletal muscle tissues, suggesting that cold exposure induced oxidative stress in this species. Furthermore, malondialdehyde (MDA) contents were significantly augmented in heart, liver and muscle, indicating cold-related oxidative damage in these tissues. In the brain, GST activity, total antioxidant capacity (T-AOC), and vitamin C content showed a significant reduction after cold acclimation. In liver, an apparent decrease was also observed in the activities of SOD and GST, as well as T-AOC, whereas CAT and GPX activities showed a prominent increase in cold-acclimated groups. In kidney, there was a significant decrease in most antioxidant enzyme activities except for SOD and GST activity. In skeletal muscle, the activity of SOD, CAT, GR as well as T-AOC significantly decreased but GPX activity showed a significant increase in cold-acclimated frogs. These findings indicate that, in general, cold acclimation induces a suppression of the antioxidant defense system. Overall, our present study systematically describes the responses of antioxidant defenses to long-term cold acclimation and these findings contribute to extending the current understanding of the mechanisms of cold tolerance in high-altitude frogs.

Independent Evolution of the MYB Family in Brown Algae.

Myeloblastosis (MYB) proteins represent one of the largest families of eukaryotic transcription factors and regulate important processes in growth and development. Studies on MYBs have mainly focused on animals and plants; however, comprehensive analysis across other supergroups such as SAR (stramenopiles, alveolates, and rhizarians) is lacking. This study characterized the structure, evolution, and expression of MYBs in four brown algae, which comprise the biggest multicellular lineage of SAR. Subfamily 1R-MYB comprised heterogeneous proteins, with fewer conserved motifs found outside the MYB domain. Unlike the SHAQKY subgroup of plant 1R-MYB, THAQKY comprised the largest subgroup of brown algal 1R-MYBs. Unlike the expansion of 2R-MYBs in plants, brown algae harbored more 3R-MYBs than 2R-MYBs. At least ten 2R-MYBs, fifteen 3R-MYBs, and one 6R-MYB orthologs existed in the common ancestor of brown algae. Phylogenetic analysis showed that brown algal MYBs had ancient origins and a diverged evolution. They showed strong affinity with stramenopile species, while not with red algae, green algae, or animals, suggesting that brown algal MYBs did not come from the secondary endosymbiosis of red and green plastids. Sequence comparison among all repeats of the three types of MYB subfamilies revealed that the repeat of 1R-MYBs showed higher sequence identity with the R3 of 2R-MYBs and 3R-MYBs, which supports the idea that 1R-MYB was derived from loss of the first and second repeats of the ancestor MYB. Compared with other species of SAR, brown algal MYB proteins exhibited a higher proportion of intrinsic disordered regions, which might contribute to multicellular evolution. Expression analysis showed that many MYB genes are responsive to different stress conditions and developmental stages. The evolution and expression analyses provided a comprehensive analysis of the phylogeny and functions of MYBs in brown algae.

EVLncRNAs 2.0: an updated database of manually curated functional long non-coding RNAs validated by low-throughput experiments.

Long non-coding RNAs (lncRNAs) play important functional roles in many diverse biological processes. However, not all expressed lncRNAs are functional. Thus, it is necessary to manually collect all experimentally validated functional lncRNAs (EVlncRNA) with their sequences, structures, and functions annotated in a central database. The first release of such a database (EVLncRNAs) was made using the literature prior to 1 May 2016. Since then (till 15 May 2020), 19 245 articles related to lncRNAs have been published. In EVLncRNAs 2.0, these articles were manually examined for a major expansion of the data collected. Specifically, the number of annotated EVlncRNAs, associated diseases, lncRNA-disease associations, and interaction records were increased by 260%, 320%, 484% and 537%, respectively. Moreover, the database has added several new categories: 8 lncRNA structures, 33 exosomal lncRNAs, 188 circular RNAs, and 1079 drug-resistant, chemoresistant, and stress-resistant lncRNAs. All records have checked against known retraction and fake articles. This release also comes with a highly interactive visual interaction network that facilitates users to track the underlying relations among lncRNAs, miRNAs, proteins, genes and other functional elements. Furthermore, it provides links to four new bioinformatics tools with improved data browsing and searching functionality. EVLncRNAs 2.0 is freely available at https://www.sdklab-biophysics-dzu.net/EVLncRNAs2/.

Long non-coding RNA UCA1 upregulates KIF20A expression to promote cell proliferation and invasion via sponging miR-204 in cervical cancer.

Cervical cancer is a female cancer with the second highest motility over the world. It is urgent to find new therapeutic methods based on long-coding RNAs and microRNAs. UCA1 was proved to be related with many human cancer types, but limited researches have been performed for the inner associations between UCA1 and cervical cancer. Eighty females who were undergoing surgeries were recruited for study in our research. We took the cervical cancer tissues and cells from them. Massive experiments and analysis were conducted to investigate the gene expressions and protein expressions about UCA1, KIF20A, and miR-204 in normal cells and cancer cells. The techniques contain real-time PCR, migration/invasion assay, western blot, in vivo experiments, and so on.We found that UCA1 expression was greatly up-regulated in cervical cancer tissues and cell lines. Our in vitro assays revealed that the suppressing of UCA1 could reduce cervical cancer cells proliferation, migration, and invasion. In addition, we found that lncRNA UCA1 could sponge miR-204 and promote the proliferation and invasion of cervical cancer cells via the up-regulating of KIF20A expression. As a result, the inhibiting of UCA1 could lower cervical cancer (CC) cells growth rate in vivo.Our results identified that UCA1 could serve as an oncogene in cervical cancer cell progression through the modulating of miR-204/KIF20A axis. It gives novel insights to the searching of novel therapeutic methods for cervical cancer.

Anti-cervical cancer activity of secondary metabolites of endophytic fungi from Ginkgo biloba.

OBJECTIVES: The purpose of this study was to isolate the secondary metabolites of endophytic fungi from Ginkgo biloba (SMEFGB) and investigate their anti-cervical cancer activity. METHODS: SMEFGB were cultured. The secondary metabolites of endophytic fungi was extracted, purified and identified. The effects of secondary metabolites on proliferation, apoptosis and migration of human cervical cancer HeLa cells were determined. In addition, the effects of SMEFGB on growth of Hela implanted tumor in mice were investigated. RESULTS: In 9 stains of endophytic fungi successfully isolated from the leaves of Ginkgo biloba, the stain J-1, J-2 and J-3 could produce podophyllotoxin. These 3 stains were identified by molecular biology. The secondary metabolites of stain J-1, J-2 and J-3 markedly inhibited the proliferation of HeLa cells, promoted their apoptosis and blocked their migration. In addition, the secondary metabolites of stain J-1, J-2 and J-3 significantly attenuated the growth of HeLa implanted tumor in mice. CONCLUSIONS: Our results indicated that SMEFGB had obvious anti-cervical cancer activity in vitro and in vivo.

miR-29b-3p regulated osteoblast differentiation via regulating IGF-1 secretion of mechanically stimulated osteocytes.

BACKGROUND: Mechanical loading is an essential factor for bone formation. A previous study indicated that mechanical tensile strain of 2500 microstrain (µÎµ) at 0.5 Hz for 8 h promoted osteogenesis and corresponding mechanoresponsive microRNAs (miRs) were identified in osteoblasts. However, in osteocytes, it has not been identified which miRs respond to the mechanical strain, and it is not fully understood how the mechanoresponsive miRs regulate osteoblast differentiation. METHODS: Mouse MLO-Y4 osteocytes were applied to the same mechanical tensile strain in vitro. Using molecular and biochemical methods, IGF-1 (insulin-like growth factor-1), PGE2 (prostaglandin E2), OPG (osteoprotegerin) and NOS (nitric oxide synthase) activities of the cells were assayed. MiR microarray and reverse transcription-quantitative polymerase chain reaction (RT-qPCR) assays were applied to select and validate differentially expressed miRs, and the target genes of these miRs were then predicted. MC3T3-E1 osteoblasts were stimulated by the mechanical tensile strain, and the miR-29b-3p expression was detected with miR microarray and RT-qPCR. Additionally, the effect of miR-29b-3p on IFG-1 secretion of osteocytes and the influence of conditioned medium of osteocytes transfected with miR-29b-3p on osteoblast differentiation were investigated. RESULTS: The mechanical strain increased secretions of IGF-1 and PGE2, elevated OPG expression and NOS activities, and resulted in altered expression of the ten miRs, and possible target genes for these differentially expressed miRs were revealed through bioinformatics. Among the ten miRs, miR-29b-3p were down-regulated, and miR-29b-3p overexpression decreased the IGF-1 secretion of osteocytes. The mechanical strain did not change expression of osteoblasts' miR-29b-3p. In addition, the conditioned medium of mechanically strained osteocytes promoted osteoblast differentiation, and the conditioned medium of osteocytes transfected with miR-29b-3p mimic inhibited osteoblast differentiation. CONCLUSIONS: In osteocytes (but not osteoblasts), miR-29b-3p was responsive to the mechanical tensile strain and regulated osteoblast differentiation via regulating IGF-1 secretion of mechanically strained osteocytes.

Genome Sequence of Pseudomonas chlororaphis Lzh-T5, a Plant Growth-Promoting Rhizobacterium with Antimicrobial Activity.

Pseudomonas chlororaphis Lzh-T5 is a plant growth-promoting rhizobacterium (PGPR) with antimicrobial activity isolated from tomato rhizosphere in the city of Dezhou, Shandong Province, China. Here, the draft genome sequence of P. chlororaphis Lzh-T5 is reported, and several functional genes related to antifungal antibiotics and siderophore biosynthesis have been found in the genome.

Draft Genome Sequence of Bacillus velezensis Lzh-a42, a Plant Growth-Promoting Rhizobacterium Isolated from Tomato Rhizosphere.

The plant growth-promoting rhizobacterium Bacillus velezensis strain Lzh-a42, which has antimicrobial activity, was isolated from tomato rhizosphere. Here, we report its genome sequence, which includes several predicted functional genes related to secondary metabolite biosynthesis, antimicrobial activity, and biofilm synthesis.

Individual construction of freeform-fabricated polycaprolactone scaffolds for osteogenesis.

The construction of engineered bone mostly focuses on simulating the extracellular matrix (ECM) for proper biological activity. However, the complexity of architecture and the variability of the mechanical properties of natural bones are related to individual differences in age, nutritional state, mechanical loading and disease status. Defect substitutions should be normed with the host natural bone, balancing architectural and mechanical adaption, as well as biological activity. Using a freeform fabrication (FFF) method, we prepared polycaprolactone (PCL) scaffolds with different architectures. With simulation of structural and mechanical parameters of rabbit femur cancellous bone, individual defect substitution with the characteristics of the rabbit femur was obtained with high porosity and connectivity. Biological adaption in vitro was examined and osteoid formation in vivo was assessed by implantation in situ. Simulating the femur cancellous bone, 300-µm FFF PCL scaffolds had better architectural and mechanical properties. The protocol produced an architecturally, mechanically and biologically adaptive construction of an individual model for rapid-prototype PCL scaffolds. A guide system was developed to accurately reproduce virtually individual defect substitutions of the bone.

Mechanical Strain Affects Some Microrna Profiles in Pre-Oeteoblasts.

MicroRNAs (miRNAs) are important regulators of cell proliferation, differentiation and function. Mechanical strain is an essential factor for osteoblast proliferation and differentiation. A previous study revealed that a physiological mechanical tensile strain of 2500 microstrain (µÎµ) at 0.5 Hz applied once a day for 1 h over 3 consecutive days promoted osteoblast differentiation. However, the mechanoresponsive miRNAs of these osteoblasts were not identified. In this study, we applied the same mechanical tensile strain to in vitro cultivated mouse MC3T3-E1 pre-osteoblasts and identified the mechanoresponsive miRNAs. Using miRNA microarray and qRT-PCR assays, the expression patterns of miRNAs were evaluated and 5 of them were found to be significantly different between the mechanical loading group and the control group: miR-3077-5p, 3090-5p and 3103-5p were significantly upregulated and miR-466i-3p and 466h-3p were downregulated. Bioinformatics analysis revealed possible target genes for these differentially expressed miRNAs. Some target genes correlated with osteoblast differentiation. These findings indicated that the mechanical strain changed the expression levels of these miRNAs. This might be a potential regulator of osteoblast differentiation and responses to mechanical strain.

MicroRNA-218, microRNA-191*, microRNA-3070a and microRNA-33 are responsive to mechanical strain exerted on osteoblastic cells.

MicroRNA (miRNA) is an important regulator of cell differentiation and function. Mechanical strain is important in the growth and differentiation of osteoblasts. Therefore, mechanresponsive miRNA may be important in the response of osteoblasts to mechanical strain. The purpose of the present study was to select and identify the mechanoresponsive miRNAs of osteoblasts. Mouse osteoblastic MC3T3-E1 cells were cultured in cell culture dishes and stimulated with a mechanical tensile strain of 2,50 µÎµ at 0.5 Hz, and the activity of alkaline phosphatase (ALP), mRNA levels of ALP, osteocalcin (OCN), and collagen type I (Col I), and protein levels of bone morphogenetic proteins (BMPs) in the cell culture medium were assayed. Following miRNA microarray and reverse transcription-quantitative polymerase chain reaction analyses, differentially expressed miRNAs in the mechanically strained cells and unstrained cells were selected and identified. Using bioinformatics analysis, the target genes of the miRNAs were then predicted. The results revealed that the mechanical strain of 2,500 µÎµ increased the activity of ALP, the mRNA levels of ALP, OCN and Col I, and the protein levels of bone morphogenetic protein(BMP)-2 and BMP-4 Continuous mechanical stimulation for 8 h had the most marked stimulant effects. miR-218, miR-191*, miR-3070a and miR-33 were identified as differentially expressed miRNAs in the mechanically strained MC3T3-E1 cells. Certain target genes of these four miRNAs were involved in osteoblastic differentiation. These findings indicated that a mechanical strain of 2,500 µÎµ, particularly for a period of 8 h, promoted osteoblastic differentiation, and the four mechanoresponsive miRNAs identified may be a potential regulator of osteoblastic differentiation and their response to mechanical strain.