A promising Artemisia capillaris Thunb. Leaf proteins with high nutrition, applicable function and excellent antioxidant activity.

The nutritional and functional properties of leaf proteins is a decisive factor for their use in food. This work was aimed to extract defatted Artemisia capillaris Thunb. (ACD) leaf proteins (ACLP), and assess ACLP nutritional quality, functional properties and in vitro antioxidant activity, as well characterize the structure. ACLP had a balanced amino acid profile and high bioavailability (protein digestibility corrected amino acid score (PDCAAS) 99.29 %). Solubility, foaming capacity and emulsifying ability of ACLP correlated positively with pH. Water and oil holding capacity were increased with temperature. Gel electrophoresis shown the protein molecular size was mainly ∼25 kDa, and random coil was the mainly secondary structure while ß-sheet was dominant regular conformation as indicated by circular dichroism (CD). ACLP performed in vitro antioxidant activity which was better after digestion. All data implied ACLP met the WHO/FAO protein quality expectations and had application potential in food.

[Analysis of Bacterial Communities and Antibiotic Resistance Genes in the Aquaculture Area of Changli County].

In order to understand the distribution of microorganisms and various antibiotic resistance genes in the aquaculture area of Changli County, Qinhuangdao, high-throughput sequencing technology was used in this study. We utilized 16S rDNA gene sequencing and metagenome sequencing methods to analyze the seawater, sediment, and gut contents of the local fish Synechogobius hasta in the aquaculture area in spring. The results showed that Proteobacteria, Firmicutes, and Bacteroidota were the dominant bacteria in seawater; and Proteobacteria, Crenarchaeota, Acidobacter, and Actinobaciota were rich in the sediment; whereas Proteobacteria, Cyanobacteria, Firmicutes, and Bacteroidota were in relatively high abundance in fish gut contents. The microbial diversity of sediment samples was the most abundant, followed by seawater samples, and the microbial diversity of fish intestinal contents was the lowest. Moreover, the microbial diversity of similar samples was relatively similar, and the microbial diversity of different types of samples was quite different. For samples at different sites, there were significant differences between seawater samples at each site, and there were small differences between sediment samples at each site, and some sediment sample groups did not have significant differences in microbial composition. In all sample groups, five ß-lactam antibiotic resistance genes (blaOXA-325, cepS, blaCARB-20, blaOXA-55, and blaTRU-1) and four aminoglycoside antibiotic resistance genes[aac(6')-IIb, amrA, aac(6')-Ie-aph(2″)-Ia, and aph(3')-Vc] were detected. There was also a certain correlation between antibiotic resistance genes and microbial communities.

The Extract of Pinellia Ternata-Induced Apoptosis of Leukemia Cells by Regulating the Expression of Bax, Bcl-2 and Caspase-3 Protein Expression in Mice.

The study aims to lessen the monetary burden on patients and society by decreasing the price of proprietary drugs used in leukemia therapy. Flow cytometry, reverse transcription polymerase chain reaction, western blot, and a patient-derived xenograft mouse model were used to confirm the therapeutic effect of Pinellia ternata extract on leukemia. Three types of leukemia cells (K562, HL-60, and C8166 cell lines) were found to undergo early apoptosis (P ≤ .05) after being exposed to P. ternata extract, as measured by flow cytometry. Reverse transcription polymerase chain reaction results showed that P. ternata extract at both middle (300 µg/mL) and high (500 µg/mL) concentrations was able to down-regulate Bcl-2 and upregulate mRNA expression of Bax and caspase-3. In the patient-derived xenograft mouse model formed by BALB/c-nu/nu nude mice, immunohistochemistry indicated that P. ternata extract effectively suppressed the proliferation of leukemia cells. Therefore, P. ternata extract at 300 µg/mL and 500 µg/mL could effectively inhibit myeloid and lymphocytic leukemia cell proliferation and promote leukemia cell apoptosis by regulating Bax/Bcl-2 and caspase-3.

Thermally Activated Delayed Fluorescence Coinage Metal Cluster Scintillator.

X-ray scintillators are widely used in medical imaging, industrial flaw detection, security inspection, and space exploration. However, traditional commercial scintillators are usually associated with a high use cost because of their substantial toxicity and easy deliquescence. In this work, an atomically precise Au-Cu cluster scintillator (1) with a thermally activated delayed fluorescence (TADF) property was facilely synthesized, which is environmentally friendly and highly stable to water and oxygen. The TADF property of 1 endows it with an ultrahigh exciton utilization rate. Combined with the effective absorption of X-ray caused by the heavy-atom effect and a limited nonradiative transition caused by close packing in the crystal state, 1 exhibits an excellent radioluminescence property. Moreover, 1 has good processability for fabricating a large, flexible thin-film device (10 cm × 10 cm) for high-resolution X-ray imaging, which can reach 40 µm (12.5 LP mm-1). The properties mentioned earlier make the coinage metal cluster promising for use as a substitute for traditional commercial scintillators.

Metformin reverses oxidative stress­induced mitochondrial dysfunction in pre­osteoblasts via the EGFR/GSK­3ß/calcium pathway.

Oxidative stress is one of the main causes of osteoblast apoptosis induced by post­menopausal osteoporosis. The authors previously found that metformin can reverse the loss of bone mass in post­menopausal osteoporosis. The present study aimed to further clarify the effects and mechanisms of action of metformin in post­menopausal osteoporosis under conditions of oxidative stress. Combined with an in­depth investigation using the transcriptome database, the association between oxidative stress and mitochondrial dysfunction in post­menopausal osteoporosis was confirmed. A pre­osteoblast model of oxidative stress was constructed, and the apoptotic rate following the addition of hydrogen peroxide and metformin was detected using CCK­8 assay and Annexin V­FITC/PI staining. Mitochondrial membrane potential was detected using the JC­1 dye, the intracellular calcium concentration was detected using Fluo­4 AM, the intracellular reactive oxygen species (ROS) level was observed using DCFH­DA, and the mitochondrial superoxide level was observed using MitoSOX Red. Bay K8644 was used to increase the level of intracellular calcium. siRNA was used to interfere with the expression of glycogen synthase kinase (GSK)­3ß. Western blot analysis was used to detect the expression of mitochondrial dysfunction­related proteins. The results revealed that oxidative stress decreased mitochondrial membrane potential and increased intracellular ROS, mitochondrial superoxide and cytoplasmic calcium levels in pre­osteoblasts; however, metformin improved mitochondrial dysfunction and reversed oxidative stress­induced injury. Metformin inhibited mitochondrial permeability transition pore opening, suppressed the cytoplasmic calcium influx and reversed pre­osteoblast apoptosis by promoting GSK­3ß phosphorylation. Moreover, it was found that EGFR was the cell membrane receptor of metformin in pre­osteoblasts, and the EGFR/GSK­3ß/calcium axis played a key role in metformin reversing the oxidative stress response of pre­osteoblasts in post­menopausal osteoporosis. On the whole, these findings provide a pharmacological basis for the use of metformin for the treatment of post­menopausal osteoporosis.

Stereoselective Construction of Chiral Linear [3]Catenanes and [2]Catenanes.

We have successfully constructed a chiral linear [3]catenane stereoselectively by coordination-driven self-assembly using a ditopic monodentate ligand containing l-valine residues with a binuclear half-sandwich organometallic rhodium(III) unit. Furthermore, by increasing the steric hindrance of the amino acid residues in the ligand, a chiral [2]catenane was obtained, which can be regarded as the factor catenane of the chiral linear [3]catenane from a topological viewpoint. Notably, the resulting molecular catenanes all exhibit complex coconformational mechanical helical chirality and planar chirality ascribed to the point chirality of the ligands. Linear [3]catenanes and [2]catenanes with the opposite chirality can be obtained by using ligands containing the corresponding d-amino acid residues, which have been confirmed by single-crystal X-ray diffraction, NMR, mass spectrometry, and circular dichroism spectroscopy.

The role of melatonin in the development of postmenopausal osteoporosis.

Melatonin is an important endogenous hormone that modulates homeostasis in the microenvironment. Recent studies have indicated that serum melatonin levels are closely associated with the occurrence and development of osteoporosis in postmenopausal women. Exogenous melatonin could also improve bone mass and increase skeletal strength. To determine the underlying mechanisms of melatonin in the prevention and treatment of postmenopausal osteoporosis, we performed this review to analyze the role of melatonin in bone metabolism according to its physiological functions. Serum melatonin is related to bone mass, the measurement of which is a potential method for the diagnosis of osteoporosis. Melatonin has a direct effect on bone remodeling by promoting osteogenesis and suppressing osteoclastogenesis. Melatonin also regulates the biological rhythm of bone tissue, which benefits its osteogenic effect. Additionally, melatonin participates in the modulation of the bone microenvironment. Melatonin attenuates the damage induced by oxidative stress and inflammation on osteoblasts and prevents osteolysis from reactive oxygen species and inflammatory factors. As an alternative drug for osteoporosis, melatonin can improve the gut ecology, remodel microbiota composition, regulate substance absorption and maintain metabolic balance, all of which are beneficial to the health of bone structure. In conclusion, our review systematically demonstrates the effects of melatonin on bone metabolism. Based on the evidence in this review, melatonin will play a more important role in the diagnosis, prevention and treatment of postmenopausal osteoporosis.

Trehalose improves palmitic acid-induced apoptosis of osteoblasts by regulating SIRT3-medicated autophagy via the AMPK/mTOR/ULK1 pathway.

Accumulation of lipid substances decreased the activity of osteoblasts. Trehalose is a typical stress metabolite to form a protective membrane on cell surface which has been demonstrated to regulate lipid metabolism. This activity of Trehalose indicates the potential effect of osteoporosis treatment. Our study aimed to determine the therapeutic effect of Trehalose in high fat-induced osteoporosis. We used palmitic acid (PA) to mimic the state of high fat and observed the apoptosis ratio of osteoblasts increased. After adding Trehalose, the apoptosis ratio decreased obviously. Autophagy is a regulatory means involved in the process of apoptosis. We detected the autophagy protein and found that the expression of Beclin-1, Atg5, and LC3 II increased, and p62 decreased after Trehalose treatment. When adding an autophagy inhibitor (3-MA), the expression of Beclin-1, Atg5, and LC3 II decreased, and p62 increased. These results indicated autophagy was an important factor involved in the preventive effect of Trehalose in PA-induced apoptosis. SIRT3 is a mitochondrial gene that can inhibit apoptosis, which has been reported to promote autophagy. We used SIRT3-siRNA to silence the expression of SIRT3 and found the effect of Trehalose was counteracted. The apoptosis ratio increased and the expression of Beclin-1, Atg5, and LC3 II decreased, p62 increased. Additionally, we also fed the mice with a high-fat diet (HFD) and intragastrical Trehalose. The results showed that Trehalose could inhibit the bone mass loss with HFD. Our study revealed the effect and mechanism of Trehalose in the treatment of osteoporosis.

Osteoporosis in Patients With Respiratory Diseases.

Climate change, environmental pollution, and virus epidemics have sharply increased the number of patients suffering from respiratory diseases in recent years. Prolonged periods of illness and drug use increase the occurrence of complications in these patients. Osteoporosis is the common bone metabolism disease with respiratory disturbance, which affects prognosis and increases mortality of patients. The problem of osteoporosis in patients with respiratory diseases needs more attention. In this review, we concluded the characteristics of osteoporosis in some respiratory diseases including COPD, asthma, COVID-19, tuberculosis, and lung cancer. We revealed that hypoxia was the common pathogenesis of osteoporosis secondary to respiratory diseases, with malnutrition and corticosteroid abuse driving the progression of osteoporosis. Hypoxia-induced ROS accumulation and activated HIF-1α lead to attenuated osteogenesis and enhanced osteoclastogenesis in patients with respiratory diseases. Tuberculosis and cancer also invaded bone tissue and reduced bone strength by direct infiltration. For the treatment of osteoporosis in respiratory patients, oral-optimized bisphosphonates were the best treatment modality. Vitamin D was a necessary supplement, both for calcium absorption in osteogenesis and for improvement of respiratory lesions. Reasonable adjustment of the dose and course of corticosteroids according to the etiology and condition of patients is beneficial to prevent the occurrence and development of osteoporosis. Additionally, HIF-1α was a potential target for the treatment of osteoporosis in respiratory patients, which could be activated under hypoxia condition and involved in the process of bone remodeling.

Melatonin Mediates Osteoblast Proliferation Through the STIM1/ORAI1 Pathway.

Based on the positive correlation between bone mineral density and melatonin levels in blood, this study confirmed that melatonin supplementation prevents postmenopausal osteoporosis. We further confirmed that melatonin promotes an increase in intracellular calcium concentrations through the STIM1/ORAI1 pathway, thereby inducing the proliferation of osteoblasts. Introduction: Osteoporosis (OP) is a progressive, systemic bone disease that is one of the main causes of disability and death in elderly female patients. As an amine hormone produced by the human pineal gland, melatonin plays an important role in regulating bone metabolism. This study intends to investigate the relationship between melatonin levels in human blood and bone density and to suggest the efficacy of melatonin in treating osteoporosis by performing in vivo and in vitro experiments. Methods: We used liquid chromatography-tandem mass spectrometry to determine the serum melatonin levels in postmenopausal women with osteoporosis and young women with a normal bone mass. The bone density, BV/TV, Tb.Th, Tb.Sp and other indicators of postmenopausal osteoporosis and mice with a normal bone mass were detected by measuring bone density and micro-CT. The intracellular calcium ion concentration was detected using fluorescence microscopy and a full-wavelength multifunctional microplate reader, and the expression of SOCE-related genes and STIM1/ORAI1 proteins was detected using PCR and WB. Results: This study confirmed that bone density positively correlates with the melatonin level in human blood. In the animal model, melatonin supplementation reverses postmenopausal osteoporosis. We explored the internal mechanism of melatonin treatment of osteoporosis. Melatonin promotes an increase in intracellular calcium ion concentrations through the STIM1/ORAI1 pathway to induce osteoblast proliferation. Conclusions: This study provides an important theoretical basis for the clinical application of melatonin in patients with osteoporosis and helps to optimize the diagnosis and treatment of postmenopausal osteoporosis.

Metformin Promotes Differentiation and Attenuates H2O2-Induced Oxidative Damage of Osteoblasts via the PI3K/AKT/Nrf2/HO-1 Pathway.

At present, the drug treatment of osteoporosis is mostly focused on inhibiting osteoclastogenesis, which has relatively poor effects. Metformin is a drug that can potentially promote osteogenic differentiation and improve bone mass in postmenopausal women. We aimed to detect the molecular mechanism underlying the osteogenic effect of metformin. Our study indicated that metformin obviously increased the Alkaline phosphatase activity and expression of osteogenic marker genes at the mRNA and protein levels. The PI3K/AKT signaling pathway was revealed to play an essential role in the metformin-induced osteogenic process, as shown by RNA sequencing. We added LY294002 to inhibit the PI3K/AKT pathway, and the results indicated that the osteogenic effect of metformin was also blocked. Additionally, the sequencing data also indicated oxidation-reduction reaction was involved in the osteogenic process of osteoblasts. We used H2O2 to mimic the oxidative damage of osteoblasts, but metformin could attenuate it. Antioxidative Nrf2/HO-1 pathway, regarded as the downstream of PI3K/AKT pathway, was modulated by metformin in the protective process. We also revealed that metformin could improve bone mass and oxidative level of OVX mice. In conclusion, our study revealed that metformin promoted osteogenic differentiation and H2O2-induced oxidative damage of osteoblasts via the PI3K/AKT/Nrf2/HO-1 pathway.

Epidemic spreading with migration in networked metapopulation.

Migration plays a crucial role in epidemic spreading, and its dynamic can be studied by metapopulation model. Instead of the uniform mixing hypothesis, we adopt networked metapopulation to build the model of the epidemic spreading and the individuals' migration. In these populations, individuals are connected by contact network and populations are coupled by individuals migration. With the network mean-field and the gravity law of migration, we establish the N-seat intertwined SIR model and obtain its basic reproduction number ℛ 0 . Meanwhile, we devise a non-markov Node-Search algorithm for model statistical simulations. Through the static network migration ansatz and ℛ 0 formula, we discover that migration will not directly increase the epidemic replication capacity. But when ℛ 0 > 1 , the migration will make the susceptive population evolve from metastable state (disease-free equilibrium) to stable state (endemic equilibrium), and then increase the influence area of epidemic. Re-evoluting the epidemic outbreak in Wuhan, top 94 cities empirical data validate the above mechanism. In addition, we estimate that the positive anti-epidemic measures taken by the Chinese government may have reduced 4 million cases at least during the first wave of COVID-19, which means those measures, such as the epidemiological investigation, nucleic acid detection in medium-high risk areas and isolation of confirmed cases, also play a significant role in preventing epidemic spreading after travel restriction between cities.

Erratum: MicroRNA-125b-1-3p mediates intervertebral disc degeneration in rats by targeting teashirt zinc finger homeobox 3.

[This corrects the article DOI: 10.3892/etm.2018.5715.].

[Corrigendum] Overexpression of septin­7 inhibits melatonin­induced cell apoptosis in human fetal osteoblastic cells via suppression of endoplasmic reticulum stress.

Subsequently to the publication of this paper, an interested reader drew to the authors' attention that Figs. 2 and 4, featured on p. 4820 and 4821 respectively, contained apparently matching control ß­actin western blots. The authors have consulted their original data, and realized that the control western blot images were inadvertently selected incorrectly for Fig. 2. The corrected version of Fig. 2, showing the relevant ß­actin bands for Fig. 2, is shown on the next page. Note that the errors in Fig. 2 did not significantly affect the results or the conclusions reported in this paper, and all the authors agree to this Corrigendum. The authors are grateful to the Editor of Molecular Medicine Reports for allowing them the opportunity to publish this corrigendum, and apologize to the readership for any inconvenience caused. [the original article was published in Molecular Medicine Reports 17: 4817­4822, 2018; DOI: 10.3892/mmr.2018.8449].

Alterations in the oral microbiome in HIV infection: causes, effects and potential interventions.

ABSTRACT: A massive depletion of CD4+ T lymphocytes has been described in early and acute human immunodeficiency virus (HIV) infection, leading to an imbalance between the human microbiome and immune responses. In recent years, a growing interest in the alterations in gut microbiota in HIV infection has led to many studies; however, only few studies have been conducted to explore the importance of oral microbiome in HIV-infected individuals. Evidence has indicated the dysbiosis of oral microbiota in people living with HIV (PLWH). Potential mechanisms might be related to the immunodeficiency in the oral cavity of HIV-infected individuals, including changes in secretory components such as reduced levels of enzymes and proteins in saliva and altered cellular components involved in the reduction and dysfunction of innate and adaptive immune cells. As a result, disrupted oral immunity in HIV-infected individuals leads to an imbalance between the oral microbiome and local immune responses, which may contribute to the development of HIV-related diseases and HIV-associated non-acquired immunodeficiency syndrome comorbidities. Although the introduction of antiretroviral therapy (ART) has led to a significant decrease in occurrence of the opportunistic oral infections in HIV-infected individuals, the dysbiosis in oral microbiome persists. Furthermore, several studies with the aim to investigate the ability of probiotics to regulate the dysbiosis of oral microbiota in HIV-infected individuals are ongoing. However, the effects of ART and probiotics on oral microbiome in HIV-infected individuals remain unclear. In this article, we review the composition of the oral microbiome in healthy and HIV-infected individuals and the possible effect of oral microbiome on HIV-associated oral diseases. We also discuss how ART and probiotics influence the oral microbiome in HIV infection. We believe that a deeper understanding of composition and function of the oral microbiome is critical for the development of effective preventive and therapeutic strategies for HIV infection.

Improved stabilization of coix seed oil in a nanocage-coating framework based on gliadin-carboxymethyl chitosan-Ca2.

Coix seed oil (CSO) is easily suffered functional-loss by oxidation and hydrothermal-treatment. The environmental stable nanocage-coating-CSO particles (OGC-Ca) by the frameworks consist of gliadins, carboxymethyl chitosan (CMCS) and Ca2+ were investigated. Results showed Ca2+ was the key controller for fabricating this nanocage-coating-frameworks, bridging macromolecule-chains with electrostatic interaction and hydrogen bonds, detected by FTIR, CD, DSC and XRD. SEM displayed new-formed velvet-like twigs after cross-linking CMCS to gliadins. Ca2+ assisted the nanocage-coating by significant down-sizing conversion OGC to OGC-Ca with consumption of twigs. OGC-Ca displayed a good stability towards heat (60-80 °C, 0-80 min), pH (3-8), NaCl (0-0.5 mM), storage (4/25 °C, 12 days), and a reduce of the pre-oxidation value of CSO in water and the improved controlled release of CSO in simulated GI tract. It illustrated GC-Ca frameworks would be a suitable delivery carrier for the CSO like pharmaceuticals and nutraceuticals for the food or medical use.

Alterations in the oral microbiome in HIV infection: causes, effects and potential interventions / 中华医学杂志(英文版)

A massive depletion of CD4+ T lymphocytes has been described in early and acute human immunodeficiency virus (HIV) infection, leading to an imbalance between the human microbiome and immune responses. In recent years, a growing interest in the alterations in gut microbiota in HIV infection has led to many studies; however, only few studies have been conducted to explore the importance of oral microbiome in HIV-infected individuals. Evidence has indicated the dysbiosis of oral microbiota in people living with HIV (PLWH). Potential mechanisms might be related to the immunodeficiency in the oral cavity of HIV-infected individuals, including changes in secretory components such as reduced levels of enzymes and proteins in saliva and altered cellular components involved in the reduction and dysfunction of innate and adaptive immune cells. As a result, disrupted oral immunity in HIV-infected individuals leads to an imbalance between the oral microbiome and local immune responses, which may contribute to the development of HIV-related diseases and HIV-associated non-acquired immunodeficiency syndrome comorbidities. Although the introduction of antiretroviral therapy (ART) has led to a significant decrease in occurrence of the opportunistic oral infections in HIV-infected individuals, the dysbiosis in oral microbiome persists. Furthermore, several studies with the aim to investigate the ability of probiotics to regulate the dysbiosis of oral microbiota in HIV-infected individuals are ongoing. However, the effects of ART and probiotics on oral microbiome in HIV-infected individuals remain unclear. In this article, we review the composition of the oral microbiome in healthy and HIV-infected individuals and the possible effect of oral microbiome on HIV-associated oral diseases. We also discuss how ART and probiotics influence the oral microbiome in HIV infection. We believe that a deeper understanding of composition and function of the oral microbiome is critical for the development of effective preventive and therapeutic strategies for HIV infection.

Metformin promotes cell proliferation and osteogenesis under high glucose condition by regulating the ROS­AKT­mTOR axis.

Metformin, a cost­effective and safe orally administered antidiabetic drug used by millions of patients, has exhibited great interest for its potential osteogenic­promoting properties in different types of cells, including mesenchymal stem cells (MSCs). Diabetic osteopathy is a common comorbidity of diabetes mellitus; however, the underlying molecular mechanisms of metformin on the physiological processes of MSCs, under high glucose condition, remain unknown. To determine the effects of metformin on the regulatory roles of proliferation and differentiation in MSCs, under high glucose conditions, osteogenesis after metformin treatment was detected with Alizarin Red S and ALP staining. The results demonstrated that high glucose levels significantly inhibited cell proliferation and osteogenic differentiation under high glucose conditions. Notably, addition of metformin reversed the inhibitory effects induced by high glucose levels on cell proliferation and osteogenesis. Furthermore, high glucose levels significantly decreased mitochondrial membrane potential (MMP), whereas treatment with metformin helped maintain MMP. Further analysis of mitochondrial function revealed that metformin significantly promoted ATP synthesis, mitochondrial DNA mass and mitochondrial transcriptional activity, which were inhibited by high glucose culture. Furthermore, metformin significantly scavenged reactive oxygen species (ROS) induced by high glucose levels, and regulated the ROS­AKT­mTOR axis inhibited by high glucose levels, suggesting the protective effects of metformin against high glucose levels via regulation of the ROS­AKT­mTOR axis. Taken together, the results of the present study demonstrated the protective role of metformin on the physiological processes of MSCs, under high glucose condition and highlighted the potential molecular mechanism underlying the effect of metformin in promoting cell proliferation and osteogenesis under high glucose condition.

Melatonin rescues glucocorticoid-induced inhibition of osteoblast differentiation in MC3T3-E1 cells via the PI3K/AKT and BMP/Smad signalling pathways.

AIMS: High-dose glucocorticoid (GC) administration causes osteoporosis. Many previous studies from our group and other groups have shown that melatonin participates in the regulation of osteoblast proliferation and differentiation, especially low concentrations of melatonin, which enhance osteoblast osteogenesis. However, the role of melatonin in glucocorticoid-induced osteoblast differentiation remains unknown. MATERIALS AND METHODS: An examination of the expression of osteoblast differentiation markers (ALP, OCN, COLL-1), as well as alkaline phosphatase staining and alkaline phosphatase enzymatic activity assay to measure osteoblast differentiation and quantifying Alizarin red S staining to measure mineralization, were performed to determine the effects of dexamethasone (Dex) and melatonin on the differentiation of MC3T3-E1 cells. We used immunofluorescence staining to detect the expression of Runx2 in melatonin-treated MC3T3-E1 cells. The expression of mRNA was determined by qRT-PCR, and protein levels were measured by western blotting. KEY FINDINGS: In the present study, we found that 100 µM Dex significantly reduced osteoblast differentiation and mineralization in MC3T3-E1 cells and that 1 µM melatonin attenuated these inhibitory effects. We found that only inhibition of PI3K/AKT (MK2206) and BMP/Smad (LDN193189) signalling abolished melatonin-induced differentiation and mineralization. Meanwhile, MK2206 decreased the expression of P-AKT and P-Smad1/5/9 and LDN193189 decreased the expression of P-Smad1/5/9 but had no obvious effect on P-AKT expression in melatonin-treated and Dex-induced MC3T3-E1 cells. SIGNIFICANCE: These findings suggest that melatonin rescues Dex-induced inhibition of osteoblast differentiation in MC3T3-E1 cells via the PI3K/AKT and BMP/Smad signalling pathways and that PI3K/AKT signalling may be the upstream signal of BMP/Smad signalling.