Upregulation of SIRT1 inhibits H2O2‑induced osteoblast apoptosis via FoxO1/β‑catenin pathway

SIRT1 maintains bone homeostasis by regulating osteoblast glycolysis through GOT1

The silent information regulator T1 (SIRT1) is linked to longevity and is a crucial mediator of osteoblast function. We investigated the direct role of Sirt1 during bone modeling and remodeling stages in vivo using Tamoxifen-inducible osteoblast-specific Sirt1 conditional knockout (cKO) mice. cKO mice exhibited lower trabecular and cortical bone mass in the distal femur. These phenotypes were coupled with lower bone formation and bone resorption. Metabolomics analysis revealed that the metabolites involved in glycolysis were significantly decreased in cKO mice. Further analysis of the quantitative acetylome revealed 11 proteins with upregulated acetylation levels in both the femur and calvaria of cKO mice. Cross-analysis identified four proteins with the same upregulated lysine acetylation site in both the femur and calvaria of cKO mice. A combined analysis of the metabolome and acetylome, as well as immunoprecipitation, gene knockout, and site-mutation experiments, revealed that Sirt1 deletion inhibited glycolysis by directly binding to and increasing the acetylation level of Glutamine oxaloacetic transaminase 1 (GOT1). In conclusion, our study suggested that Sirt1 played a crucial role in regulating osteoblast metabolism to maintain bone homeostasis through its deacetylase activity on GOT1. These findings provided a novel insight into the potential targeting of osteoblast metabolism for the treatment of bone-related diseases.

Sirtuins in intervertebral disc degeneration: current understanding

BACKGROUND

Intervertebral disc degeneration (IVDD) is one of the etiologic factors of degenerative spinal diseases, which can lead to a variety of pathological spinal conditions such as disc herniation, spinal stenosis, and scoliosis. IVDD is a leading cause of lower back pain, the prevalence of which increases with age. Recently, Sirtuins/SIRTs and their related activators have received attention for their activity in the treatment of IVDD. In this paper, a comprehensive systematic review of the literature on the role of SIRTs and their activators on IVDD in recent years is presented. The molecular pathways involved in the regulation of IVDD by SIRTs are summarized, and the effects of SIRTs on senescence, inflammatory responses, oxidative stress, and mitochondrial dysfunction in myeloid cells are discussed with a view to suggesting possible solutions for the current treatment of IVDD.

PURPOSE

This paper focuses on the molecular mechanisms by which SIRTs and their activators act on IVDD.

METHODS

A literature search was conducted in Pubmed and Web of Science databases over a 13-year period from 2011 to 2024 for the terms "SIRT", "Sirtuin", "IVDD", "IDD", "IVD", "NP", "Intervertebral disc degeneration", "Intervertebral disc" and "Nucleus pulposus".

RESULTS

According to the results, SIRTs and a large number of activators showed positive effects against IVDD.SIRTs modulate autophagy, myeloid apoptosis, oxidative stress and extracellular matrix degradation. In addition, they attenuate inflammatory factor-induced disc damage and maintain homeostasis during disc degeneration. Several clinical studies have reported the protective effects of some SIRTs activators (e.g., resveratrol, melatonin, honokiol, and 1,4-dihydropyridine) against IVDD.

CONCLUSION

The fact that SIRTs and their activators play a hundred different roles in IVDD helps to better understand their potential to develop further treatments for IVDD.

NOVELTY

This review summarizes current information on the mechanisms of action of SIRTs in IVDD and the challenges and limitations of translating their basic research into therapy.

Icariin promotes osteogenic differentiation of human bone marrow mesenchymal stem cells by regulating USP47/SIRT1/Wnt/β-catenin

Icariin has been shown to promote osteogenic differentiation of bone marrow mesenchymal stem cells (BMSCs). However, the underlying molecular mechanism by which Icariin regulates osteogenic differentiation needs to be further revealed. The viability of BMSCs was assessed by cell counting kit 8 assay. BMSC osteogenic differentiation ability was evaluated by detecting alkaline phosphatase activity and performing alizarin red S staining. The protein levels of osteogenic differentiation-related markers, sirtuin 1 (SIRT1), ubiquitin-specific protease 47 (USP47), and Wnt/β-catenin-related markers were determined using western blot. SIRT1 mRNA level was measured using quantitative real-time PCR. The regulation of USP47 on SIRT1 was confirmed by ubiquitination detection and co-immunoprecipitation analysis. Icariin could promote BMSC osteogenic differentiation. SIRT1 expression was enhanced by Icariin, and its knockdown suppressed Icariin-induced BMSC osteogenic differentiation. Moreover, deubiquitinating enzyme USP47 could stabilize SIRT1 protein expression. Besides, SIRT1 overexpression reversed the inhibiting effect of USP47 knockdown on BMSC osteogenic differentiation, and USP47 knockdown also restrained Icariin-induced BMSC osteogenic differentiation. Additionally, Icariin enhanced the activity of the Wnt/β-catenin pathway by upregulating SIRT1. Icariin facilitated BMSC osteogenic differentiation via the USP47/SIRT1/Wnt/β-catenin pathway.

Exogenous hydrogen sulfide alleviates hepatic endoplasmic reticulum stress via SIRT1/FoxO1/PCSK9 pathway in NAFLD

High-fat-induced endoplasmic reticulum (ER) stress has been the main reason for the occurrence and development of nonalcoholic fatty liver disease (NAFLD). Hydrogen sulfide (H2 S) produces a marked effect on regulating lipid metabolism and antioxidation, whose effects on ER stress of NAFLD are still unclear. Here, we studied the influence of exogenous H2 S on NAFLD and its potential mechanism. In vivo, NAFLD model was induced by high-fat diet (HFD) for 12 weeks, followed by intraperitoneal injection of exogenous H2 S intervention for 4 weeks. HepG2 cells exposure to lipid mixture (LM) were used as vitro model to explore the potential mechanism. We found exogenous H2 S significantly inhibited the hepatic ER stress and improved the liver fat deposition of HFD-fed mice. These similar results were also observed in HepG2 cells dealt with LM after exogenous H2 S treatment. Further mechanism studies showed exogenous H2 S strengthened the combination of FoxO1 with the PCSK9 promoter gene through SIRT1-mediated deacetylation, thereby inhibiting the PCSK9 expression to relieve the hepatic ER stress. However, SIRT1 knockout eliminated the effects of exogenous H2 S on FoxO1 deacetylation, PCSK9 inhibition, and remission of hepatic ER stress and steatosis. In conclusion, exogenous H2 S improved NAFLD by inhibiting hepatic ER stress through SIRT1/FoxO1/PCSK9 pathway. Exogenous H2 S and ER stress may be potential drug and target for the treatment of NAFLD, respectively.

Adiponectin overexpression promotes fracture healing through regulating the osteogenesis and adipogenesis balance in osteoporotic mice

INTRODUCTION

Osteoporosis invariably manifests as loss of bone, which is replaced by adipose tissue; this can easily lead to fractures, accompanied by delayed and poor healing. Adiponectin (APN) balances osteogenesis and adipogenesis in bone marrow mesenchymal stem cells (BMSCs). Therefore, this study explored whether adiponectin promotes bone fracture healing by regulating the balance between osteogenesis and adipogenesis.

MATERIALS AND METHODS

We used adenovirus overexpression vectors carrying APN (Ad-APN-GFP) to treat ovariectomized (OVX) mouse BMSCs and osteoporotic bone fractures to investigate the role of APN in bone microenvironment metabolism in osteoporotic fractures. We subsequently established an OVX mice and bone fracture model using Ad-APN-GFP treatment to investigate whether APN could promote bone fracture healing in osteoporotic mice.

RESULTS

The experimental results showed that APN is a critical molecule in diverse differentiation directions in OVX mouse BMSCs, with pro-osteogenesis and anti-adipogenesis properties. Importantly, our study revealed that Ad-APN-GFP treatment facilitates bone generation and healing around the osteoporotic fracture ends. Moreover, we identified that Sirt1 and Wnt signaling were closely related to the pro-osteogenesis and anti-adipogenesis commitment of APN in OVX mouse BMSCs and femoral tissues.

CONCLUSION

We demonstrated that APN overexpression facilitates bone fracture healing in osteoporosis. Furthermore, APN overexpression promoted bone formation in OVX mouse BMSCs and bone fracture ends by regulating the balance between osteogenesis and adipogenesis both in vitro and in vivo.

Comprehensive analysis of epigenetics mechanisms in osteoporosis

Epigenetic modification pertains to the alteration of genetic-expression, which could be transferred to the next generations, without any alteration in the fundamental DNA sequence. Epigenetic modification could include various processes such as DNA methylation, histone alteration, non-coding RNAs (ncRNAs), and chromatin adjustment are among its primary operations. Osteoporosis is a metabolic disorder that bones become more fragile due to the decrease in mineral density, which could result in a higher risk of fracturing. Recently, as the investigation of the causal pathology of osteoporosis has been progressed, remarkable improvement has been made in epigenetic research. Recent literatures have illustrated that epigenetics is estimated to be one of the most contributing factors to the emergence and progression of osteoporosis. This dissertation primarily focuses on indicating the research progresses of epigenetic mechanisms and also the regulation of bone metabolism and the pathogenesis of osteoporosis in light of the significance of epigenetic mechanisms. In addition, it aims to provide new intelligence for the treatment of diseases related to bone metabolism.

Association between global biomarker of oxidative stress and quantitative ultrasound parameters in middle-aged and elderly adults: A cross-sectional study

Introduction

With the population aging, osteoporosis has become a major public health concern. Elevated oxidative stress is a vital detrimental factor for bone health. Compared to common oxidative stress-related biomarkers, Fluorescent Oxidation Products (FlOPs) reflect the global levels of oxidation from proteins, lipids, and DNA. Nevertheless, whether plasma FlOP levels are related to bone health measured by Quantitative ultrasound (QUS) is unclear. Thus, the present study examined the association between FlOPs and QUS parameters in middle-aged and elderly adults.

Methods

This community-based cross-sectional study was conducted in Changchun, northeast China. Plasma FlOPs were determined by a fluorescent microplate reader at a wavelength of 320/420 nm (excitation/emission). QUS parameters [speed of sound (SOS) and broadband ultrasound attenuation (BUA)] of the calcaneus were assessed by an ultrasound bone densitometer. We used multivariable linear regression to examine the association between FlOPs and QUS parameters.

Results

A total of 491 subjects were included in this study. Their average age was 65.2 years (standard deviation [SD]: 9.7 years). FlOPs were inversely associated with SOS (β for an increase of logarithmic interquartile range = -10.64; P = 0.018). Higher FlOP levels were marginally associated with lower SOS in females (β for an increase of logarithmic interquartile range = -9.68, P = 0.066), but not in males (β for an increase of logarithmic interquartile range = -11.84, P = 0.131). No significant relationship between FlOPs and BUA was observed.

Conclusions

Plasma FlOP levels were inversely associated with SOS, but not with BUA in middle-aged and elderly adults.

Inflammatory Modulation of miR-155 Inhibits Doxorubicin-Induced Testicular Dysfunction via SIRT1/FOXO1 Pathway: Insight into the Role of Acacetin and Bacillus cereus Protease

Doxorubicin (DOX) is a chemotherapeutic agent that can disrupt testicular function leading to male infertility. This study examined the protective role of natural flavone, acacetin (ACA), and a protease of Bacillus cereus bacteria (B. cereus) as well as the potential role of miR-155/SIRT1/FOXO1 network in DOX-induced testicular injury. Twenty-four male Wistar rats were randomly allocated into four groups and treated as follows: Control, DOX (1 mg/kg, i.p) every other day for 21 days with a total dose equal to 10 mg/kg throughout the experiment, and pre-treated groups that received ACA (5 mg/kg/day, p.o) or B. cereus protease (36 mg/kg/day, p.o) for a week prior to DOX administration. DOX challenge reduced the testis weight coefficient, serum testosterone, and testicular 17β-hydroxysteroid dehydrogenase (17β-HSD). DOX caused a significant increase in testicular oxidative stress, inflammatory, and apoptotic markers. Aberrant testicular miR-34c, a germ-specific miRNA, and miR-155 expressions were observed, along with decreased protein expression of sirtuin1 (SIRT1) dependent forkhead box 1 (FOXO1) acetylation which induces apoptosis. Besides, abnormal histopathological architecture and a marked reduction in the testicular expression of proliferating cell nuclear antigen (PCNA) were observed. ACA or protease administration significantly improved the histopathological and immunohistochemical pictures compared with DOX alone and renovated testicular functions. Interestingly, treatment with protease was more significant than treatment with ACA in ameliorating DOX-induced testicular injury. Taken together, this study reveals the prophylactic role of these two regimens on male fertility by exhibiting antioxidant, anti-inflammatory, and anti-apoptotic effects against DOX-elicited testicular damage, possibly via modulating miR-155/SIRT1/FOXO1 network.

Osteomyelitis, Oxidative Stress and Related Biomarkers

Bone is a very dynamic tissue, subject to continuous renewal to maintain homeostasis through bone remodeling, a process promoted by two cell types: osteoblasts, of mesenchymal derivation, are responsible for the deposition of new material, and osteoclasts, which are hematopoietic cells, responsible for bone resorption. Osteomyelitis (OM) is an invasive infectious process, with several etiological agents, the most common being Staphylococcus aureus, affecting bone or bone marrow, and severely impairing bone homeostasis, resulting in osteolysis. One of the characteristic features of OM is a strong state of oxidative stress (OS) with severe consequences on the delicate balance between osteoblastogenesis and osteoclastogenesis. Here we describe this, analyzing the effects of OS in bone remodeling and discussing the need for new, easy-to-measure and widely available OS biomarkers that will provide valid support in the management of the disease.

Effect of Sirtuin-1 and Wnt/β-Catenin Signaling Pathway in Rat Model of Spinal Cord Injury

Sirtuin-1 (SIRT1) has anti-inflammatory and antioxidant effects and has been reported to be involved in spinal cord injury (SCI). Wnt/β-catenin signal has been shown to play a critical role in the pathogenesis of chronic diseases, and it participated in the recovery of nerve function after SCI. However, the specific link between them in SCI is unclear. In addition, targeting posttraumatic astrocyte apoptosis is crucial for improving neural degeneration and locomotor function. Therefore, in this article, we studied the relationship of β-catenin and SIRT1 using in the SCI rat model and primary astrocyte treated with hydrogen peroxide (H2O2) or lithium chloride (LiCl). Results showed that after SCI, SCI area and motor function recover over time, and β-catenin is gradually increased to the seventh day and then in turn decreases until 4 weeks, positively correlated with cell apoptosis. The expression of SIRT1 and downstream FOXO4 gradually increased, and β-catenin is negatively correlated with SIRT1 expression. Moreover, treatment with H2O2 in primary cultured astrocyte significantly increased β-catenin and Caspase-3 expression, while decreased SIRT1 and Forkhead box O- (FOXO-) 4. The immunofluorescence results are consistent with this. Administration of LiCl further aggravates the above results. These findings suggest that SIRT1 is negatively correlated with β-catenin in SCI, which promotes the apoptosis of motor neuron cells, which may be related to the participation of FOXO4.

Protective Effect of Grape Seed Proanthocyanidins on Oxidative Damage of Chicken Follicular Granulosa Cells by Inhibiting FoxO1-Mediated Autophagy

A significant decrease in poultry egg production occurs due to ovarian aging and autophagy is one of the important factors of ovarian aging that is induced predominantly by oxidative stress. Increasing evidence showed potential roles of plant-derived grape seed proanthocyanidin (GSPs) in protecting ovarian granulosa cells (GCs) from oxidative damage, although the underlying mechanism is still unclear. Here we investigated the possible functions of autophagy involved in the preventive effect of GSPs on oxidative stress in the GCs of ovarian hierarchical follicles of laying chickens. The results showed that increased autophagy was observed in the aging hens (580-day-old, D580) compared with the peak-lay hens (D280). Treatment of GSPs significantly restored the elevated autophagy and decreased viability of cultured D280 chicken GCs that were elicited by hydrogen peroxide. GSPs also suppressed the increased autophagy in the natural aging hens. Similar to the effect of GSPs on GC viability, inhibition of autophagy also showed a protective effect on the decreased viability of GCs under oxidative damage. However, GSPs were not able to provide further protection in GCs that were pretreated with 3-methyladenine (an autophagy inhibitor). In addition to its promoting action on antioxidant capacity, treatment with GSPs increased survival of GCs from autophagy that was caused by oxidative stress through the FoxO1-related pathway. Inhibition of FoxO1 or activation of PI3K-Akt pathway by GSPs increased the confrontation of GCs to oxidative damage and decreased autophagy in GCs. In addition, activation of the SIRT1 signal inhibited the GCs autophagy that was caused by oxidative stress via GSPs-induced deacetylation of FoxO1. These results revealed a new mechanism of GSPs against oxidative stress of GCs via inhibiting FoxO1, which was probably a possible target for alleviating ovarian aging in laying poultry.

Uncovering Hidden Mechanisms of Different Prescriptions Treatment for Osteoporosis via Novel Bioinformatics Model and Experiment Validation

Osteoporosis (OP) is a systemic disease susceptible to fracture due to the decline of bone mineral density and bone mass, the destruction of bone tissue microstructure, and increased bone fragility. At present, the treatments of OP mainly include bisphosphonates, hormone therapy, and RANKL antibody therapy. However, these treatments have observable side effects and cannot fundamentally improve bone metabolism. Currently, the prescription of herbal medicine and their derived proprietary Chinese medicines are playing increasingly important roles in the treatment of OP due to their significant curative effects and few side effects. Among these prescriptions, Gushukang Granules (GSK), Xianling Gubao Capsules (XLGB), and Er-xian Decoction (EXD) are widely employed at the clinic on therapy of OP, which also is in line with the compatibility principle of “different treatments for the same disease” in herbal medicine. However, at present, the functional interpretation of “different treatments for the same disease” in herbal medicine still lacks systematic quantitative research, especially on the detection of key component groups and mechanisms. To solve this problem, we designed a new bioinformatics model based on random walk, optimized programming, and information gain to analyze the components and targets to figure out the Functional Response Motifs (FRMs) of different prescriptions for the therapy of OP. The distribution of high relevance score, the number of reported evidence, and coverage of enriched pathways were performed to verify the precision and reliability of FRMs. At the same time, the information gain and target influence of each component was calculated, and the key component groups in all FRMs of each prescription were screened to speculate the potential action mode of different prescriptions on the same disease. Results show that the relevance score and the number of reported evidence of high reliable genes in FRMs were higher than those of the pathogenic genes of OP. Furthermore, the gene enrichment pathways in FRMs could cover 79.6, 81, and 79.5% of the gene enrichment pathways in the component-target (C-T) network. Functional pathway enrichment analysis showed that GSK, XLGB, and EXD all treat OP through osteoclast differentiation (hsa04380), calcium signaling pathway (hsa04020), MAPK signaling pathway (hsa04010), and PI3K-Akt signaling pathway (hsa04151). Combined with experiments, the key component groups and the mechanism of “different treatments for the same disease” in the three prescriptions and proprietary Chinese medicines were verified. This study provides methodological references for the optimization and mechanism speculation of Chinese medicine prescriptions and proprietary Chinese medicines.

Genes and Longevity of Lifespan

Aging is a complex process indicated by low energy levels, declined physiological activity, stress induced loss of homeostasis leading to the risk of diseases and mortality. Recent developments in medical sciences and an increased availability of nutritional requirements has significantly increased the average human lifespan worldwide. Several environmental and physiological factors contribute to the aging process. However, about 40% human life expectancy is inherited among generations, many lifespan associated genes, genetic mechanisms and pathways have been demonstrated during last decades. In the present review, we have evaluated many human genes and their non-human orthologs established for their role in the regulation of lifespan. The study has included more than fifty genes reported in the literature for their contributions to the longevity of life. Intact genomic DNA is essential for the life activities at the level of cell, tissue, and organ. Nucleic acids are vulnerable to oxidative stress, chemotherapies, and exposure to radiations. Efficient DNA repair mechanisms are essential for the maintenance of genomic integrity, damaged DNA is not replicated and transferred to next generations rather the presence of deleterious DNA initiates signaling cascades leading to the cell cycle arrest or apoptosis. DNA modifications, DNA methylation, histone methylation, histone acetylation and DNA damage can eventually lead towards apoptosis. The importance of calorie restriction therapy in the extension of lifespan has also been discussed. The role of pathways involved in the regulation of lifespan such as DAF-16/FOXO (forkhead box protein O1), TOR and JNK pathways has also been particularized. The study provides an updated account of genetic factors associated with the extended lifespan and their interactive contributory role with cellular pathways.

Antioxidant Activity and the Potential Mechanism of the Fruit From Ailanthus altissima Swingle

The fruits of Ailanthus altissima Swingle (AS) possess a variety of pharmacological activities. Its antioxidant activity and the potential mode of action have not yet been investigated. In in vitro studies, AS revealed the strong reducing power and DPPH scavenging effect, but hydroxyl radical scavenging activity and ferrous ions-chelating ability were not strong. Meanwhile, the oxidative stress RAW264.7 cell injury model was established, the low and medium-doses of AS showed significant protective effects on the viability of H₂O₂-treated cells by CCK-8 method. Besides, three doses of AS all increased the activities of SOD, CAT, and GSH-Px and decreased the MDA level compared with the H₂O₂ group, suggesting it significantly relieved oxidative stress of cells. The active ingredients and related targets of AS were collected by HERB and Swiss Target Prediction database, the common targets of drugs and diseases database were conducted by GeneCards database platform and the Venny platform. We screened the core targets of AS like threonine kinase1 (AKT1), mitogen-activated protein kinase 1 (MAPK1), sirtuin-1 (SIRT1), mechanistic target of rapamycin kinase (MTOR) by STRING database, and the key pathways involved PI3K-AKT and FoxO signaling pathway by KEGG pathway enrichment analysis. Besides, qRT-PCR revealed AS preconditioning significantly up-regulated the expression level of AKT1, SIRT1, MAPK1, and MTOR in model cells, and the effect was related to the regulation of FoxO and PI3K/AKT signaling pathway. In summary, AS showed significant antioxidant activity and its potential mechanism was regulating FoxO and PI3K/AKT signaling pathway.

Up-regulation of SIRT1 induced by 17beta-estradiol promotes autophagy and inhibits apoptosis in osteoblasts

Osteoporosis is a common systemic skeletal metabolism disorder resulting in bone fragility and increased fracture risk. Silent information regulator factor 2 homolog 1 (SIRT1) is crucial in the regulation of several biological processes, including bone metabolism, autophagy, apoptosis, and aging. This study aimed to assess whether the up-regulation of SIRT1 induced by 17beta-estradiol (17β-E2) could promote autophagy and inhibit apoptosis in osteoblasts via the AMPK-mTOR and FOXO3a pathways, respectively. The study found that 17β-E2 (10^-6 M) administration induced the up-regulation of SIRT1 in osteoblasts. Up-regulation of SIRT1 induced by 17β-E2 increased the expression level of LC3, Beclin-1, Bcl-2, p-AMPK, FOXO3a but decreased caspase-3 and p-mTOR expression, and then promoted autophagy and inhibited apoptosis. More autophagosomes were observed under a transmission electron microscope (TEM) in 17β-E2 and SRT1720 (a selective SIRT1 activator) co-treated group. When Ex527 (a SIRT1-specific inhibitor) was pretreated, the reversed changes were observed. Taken together, our findings demonstrated that the up-regulation of SIRT1 induced by 17β-E2 could promote autophagy via the AMPK-mTOR pathway and inhibit apoptosis via the FOXO3a activation in osteoblasts, and SIRT1 might become a more significant target in osteoporosis treatment.

Organ-differential Roles of Akt/FoxOs Axis as a Key Metabolic Modulator during Aging

FoxOs and their post-translational modification by phosphorylation, acetylation, and methylation can affect epigenetic modifications and promote the expression of downstream target genes. Therefore, they ultimately affect cellular and biological functions during aging or occurrence of age-related diseases including cancer, diabetes, and kidney diseases. As known for its key role in aging, FoxOs play various biological roles in the aging process by regulating reactive oxygen species, lipid accumulation, and inflammation. FoxOs regulated by PI3K/Akt pathway modulate the expression of various target genes encoding MnSOD, catalases, PPARγ, and IL-1β during aging, which are associated with age-related diseases. This review highlights the age-dependent differential regulatory mechanism of Akt/FoxOs axis in metabolic and non-metabolic organs. We demonstrated that age-dependent suppression of Akt increases the activity of FoxOs (Akt/FoxOs axis upregulation) in metabolic organs such as liver and muscle. This Akt/FoxOs axis could be modulated and reversed by antiaging paradigm calorie restriction (CR). In contrast, hyperinsulinemia-mediated PI3K/Akt activation inhibited FoxOs activity (Akt/FoxOs axis downregulation) leading to decrease of antioxidant genes expression in non-metabolic organs such as kidneys and lungs during aging. These phenomena are reversed by CR. The results of studies on the process of aging and CR indicate that the Akt/FoxOs axis plays a critical role in regulating metabolic homeostasis, redox stress, and inflammation in various organs during aging process. The benefical actions of CR on the Akt/FoxOs axis in metabolic and non-metabolic organs provide further insights into the molecular mechanisms of organ-differential roles of Akt/FoxOs axis during aging.

Advances in the occurrence and biotherapy of osteoporosis

Osteoporosis (OP) is a bone metabolic disease, is characterized by degeneration of bone structure and decreased bone mass. It happens in more than 1/3 women and 1/5 men of over than 50 years old, which affects the health and lives of people. The main mechanism of OP is mainly that the dynamic balance between the bone formation and resorption is broken, so that bone resorption is more than bone formation. It is prone to result in bone metabolism disorder. There are many precipitating factor such as elder age, low hormone level, genetic factors and bad hobbies. At the same time, the occurrence of the OP and its complications has different degrees of impact on people's quality of life. Based on the current understanding of the OP, we summarized the etiology, current clinical drugs and potential targeting therapy for OP. Although the research have made many progress in explore what is the novel mechanism and how to improve the effect, there are still many problems in the treatment method that limit its application prospects and need to be solved. In this review, we mainly focus on the mechanism of OP and related research on the targeted treatment of OP. Hopefully, our summary will provide a reference to develop some novel strategies for the target therapy of OP.

Dexmedetomidine reversed hypoxia/reoxygenation injury-induced oxidative stress and endoplasmic reticulum stress-dependent apoptosis of cardiomyocytes via SIRT1/CHOP signaling pathway

We aimed to investigate the protective role and mechanism of dexmedetomidine (DEX) on H9c2 cardiomyocytes after hypoxia/reoxygenation (H/R) injury. Six experimental groups were designed as follows: normal control group (group C), H/R group, H/R + DEX group, H/R + gastrodin group, H/R + Ex527 (SIRT1 inhibitor) group, and H/R + DEX + Ex527 group. Lactate dehydrogenase (LDH) activity and the levels of oxidative stress-related enzymes such as malondialdehyde (MDA), superoxide dismutase (SOD), catalase (CAT) and glutathione (GSH) were measured using corresponding commercial kits. Cell counting kit (CCK)-8 assay was used to detect cell survival rate while flow cytometry and caspase 3/7 activity were used to determine cell apoptosis, respectively. Western blot was used to detect the expression of silent information regulator 1 (SIRT1), C/EBP homologous protein (CHOP), cleaved-caspase-12/3 and pro-caspase-12/3 in each group. From our findings, when compared with H/R, H/R + Ex527 and H/R + DEX + Ex527 groups, DEX pretreatment of cells in H/R + DEX group significantly increased cell survival rate, and simultaneously reduced LDH activity, oxidative stress and the apoptosis rate of H9c2 cells with H/R injury. Moreover, DEX up-regulated SIRT1 expression level and down-regulated the levels of endoplasmic reticulum (ER) stress-related markers such as CHOP, cleaved-caspase-12 and cleaved-caspase-3, respectively. Ex527 could completely block DEX-induced upregulated expression of SIRT1, and partially blocked the DEX-induced downregulated expression levels of CHOP, cleaved-caspase-12 and cleaved-caspase-3. These results proved that DEX reversed H/R injury-induced oxidative stress and ER stress-dependent apoptosis of cardiomyocytes via SIRT1/CHOP signaling pathway.

Role of sirtuins in bone biology: Potential implications for novel therapeutic strategies for osteoporosis

The decline in bone mass and bone strength and musculoskeletal problems associated with aging constitute a major challenge for affected individuals and the healthcare system globally. Sirtuins 1-7 (SIRT1-SIRT7) are a family of nicotinamide adenine dinucleotide-dependent deacetylases with remarkable abilities to promote longevity and counteract age-related diseases. Sirtuin knockout and transgenic models have provided novel insights into the function and signaling of these proteins in bone homeostasis. Studies have revealed that sirtuins play a critical role in normal skeletal development and homeostasis through their direct action on bone cells and that their dysregulation might contribute to different bone diseases. Preclinical studies have demonstrated that mice treated with sirtuin agonists show protection against age-related, postmenopausal, and immobilization-induced osteoporosis. These findings suggest that sirtuins could be potential targets for the modulation of the imbalance in bone remodeling and treatment of osteoporosis and other bone disorders. The aim of this review was to provide a comprehensive updated review of the current knowledge on sirtuin biology, focusing specifically on their roles in bone homeostasis and osteoporosis, and potential pharmacological interventions targeting sirtuins for the treatment of osteoporosis.

1α,25-Dihydroxyvitamin D3 ameliorates diabetes-induced bone loss by attenuating FoxO1-mediated autophagy

Autophagy is vital for maintaining cellular homeostasis through removing impaired organelles. It has recently been found to play pivotal roles in diabetes mellitus (DM), which is associated with increased bone fracture risk and loss of bone density. However, the mechanism whereby autophagy modulates DM-induced bone loss is not fully elucidated. Previous work has shown that 1α,25-Dihydroxyvitamin D3 (1,25D) exerts positive effects on autophagy, thus affecting bone metabolism. Here, we investigated whether autophagy was involved in the regulation of diabetic bone metabolism. Using Micro-CT, Elisa, histology, and histomorphometry analysis, we demonstrated that 1,25D rescues glucose metabolism dysfunction and ameliorates bone loss in diabetic mice. In vitro, 1,25D alleviated primary osteoblast dysfunction and intracellular oxidative stress through reducing prolonged high-glucose-mediated excessive autophagy in primary osteoblasts, reflected by decreased protein level of Beclin1 and LC3. Of note, the autophagy activator rapamycin (RAP) ablated the positive effects of 1,25D in diabetic environment, leading to a marked increase in autolysosomes and autophagosomes, examined by mRFP-GFP-LC3 fluorescence double labeling. The excessive autophagy induced by high glucose was deleterious to proliferation and differentiation of primary osteoblasts. Additionally, biochemical studies identified that PI3K/Akt signaling could be activated by 1,25D, resulting in the inhibition of FoxO1. We confirmed that FoxO1 deficiency alleviated high-glucose-induced autophagy and improved biological functions of primary osteoblasts. Together, our results suggest that the PI3K/Akt/FoxO1 signaling pathway is involved in the osteoprotective effect of 1,25D by attenuating autophagy in diabetes, providing a novel insight for the prevention and treatment of diabetes-caused bone loss.

MicroRNA-142 protects MC3T3-E1 cells against high glucose-induced apoptosis by targeting β-catenin

Osteoporosis, characterized by decreased mineral density and bone mass, is triggered by various detrimental factors and often causes further complications, including fractures. Aberrant expression of microRNAs (miRs) has been associated with the pathogenesis of osteoporosis. Recently, miR-142 was reported to be downregulated in osteoblasts; however, the underlying mechanism of miR-142 in mediating the development of osteoporosis remains unclear. In the present study, high glucose induced the downregulation of miR-142 mRNA expression and promoted the apoptosis of MC3T3-E1 cells. miR-142-mimics significantly protected against high glucose-induced apoptosis, upregulated the expression levels of B-cell lymphoma 2 (Bcl-2) and downregulated the protein expression levels of β-catenin, Bcl-2 associated X (Bax) and caspase-3. Furthermore, β-catenin was identified as a direct target of miR-142 using luciferase reporter assays. Similar to the effects of miR-142 inhibitors, overexpression of β-catenin aggravated the apoptosis of MC3T3-E1 cells, as demonstrated by the upregulation of Bax and caspase-3, and the downregulation of Bcl-2 expression levels. In conclusion, miR-142 protects MC3T3-E1 cells against high glucose-induced apoptosis by targeting β-catenin.

Cytoprotective effects of fermented oyster extracts against oxidative stress-induced DNA damage and apoptosis through activation of the Nrf2/HO-1 signaling pathway in MC3T3-E1 osteoblasts

Osteoblast damage by oxidative stress has been recognized as a cause of bone-related disease, including osteoporosis. Recently, we reported that fermented Pacific oyster (Crassostrea gigas) extracts (FO) inhibited osteoclastogenesis and osteoporosis, while promoting osteogenesis. However, since the beneficial potential of FO on osteoblasts is not well known, in the present study, we investigated the cytoprotective effect of FO against oxidative stress in MC3T3-E1 osteoblasts. Our results demonstrated that FO inhibited hydrogen peroxide (H2O2)-induced DNA damage and cytotoxicity through the rescue of mitochondrial function by blocking abnormal ROS accumulation. FO also prevented apoptosis by suppressing loss of mitochondrial membrane potential and cytosolic release of cytochrome c, decreasing the rate of Bax/Bcl-2 expression and reducing the activity of caspase-9 and caspase-3 in H2O2-stimulated MC3T3-E1 osteoblasts, suggesting that FO protected MC3T3-E1 osteoblasts from the induction of caspase dependent- and mitochondria-mediated apoptosis by oxidative stress. In addition, FO markedly promoted the activation of nuclear factor-erythroid-2-related factor 2 (Nrf2), which was associated with the enhanced expression of heme oxygenase-1 (HO-1). However, inhibiting the expression of HO-1 by artificially blocking the expression of Nrf2 using siRNA significantly eliminated the protective effect of FO, indicating that FO activates the Nrf2/HO-1 signaling pathway in MC3T3-E1 osteoblasts to protect against oxidative stress. Based on the present data, FO is thought to be useful as a potential therapeutic agent for the inhibition of oxidative stress in osteoblasts.

miRNA‑384‑5p regulates the progression of Parkinson's disease by targeting SIRT1 in mice and SH‑SY5Y cell

Parkinson's disease (PD) is the second most common neurodegenerative disorder. miR-384-5p expression has been shown to be increased in an in vitro model of PD; however, it remains unknown whether there are other molecules that can be regulated by miR-384-5p in in vivo and in vitro models of PD; thus, the present study aimed to elucidate this matter. Rotenone was applied for the establishment of in vitro and in vivo models of PD in the present study. Motor disability and equilibrium were determined by a swimming test and traction test, respectively. mRNA and protein levels were detected by reverse transcription-quantitative polymerase chain reaction (RT-qPCR) and western blot analysis, respectively. The association between miR-384-5p and Sirtuin 1 (SIRT1) expression was verified by dual luciferase reporter assay. The α-synuclein aggregation was evaluated by immunofluorescence. The results from the in vitro model of PD demonstrated that, the mice in the PD group exhibited decreased scores in the swimming test and traction test, which were accompanied by increased α-synuclein aggregation. In addition, the expression of miR-384-5p, which targeted the 3′untranslated region (3′UTR) of SIRT1, was verified to be increased in mice and SH-SY5Y cells in the PD group, whereas SIRT1 exhibited the opposite changes. Moreover, increased mRNA and protein levels of p53 and FOXO1 were observed in mice and SH-SY5Y cells in the PD group. In addition, the SH-SY5Y cells in the PD group exhibited a higher cell apoptotic rate. On the whole, the findings of this study demonstrate that miRNA-384-5p promotes the progression of PD by targeting SIRT1.

Blueberry juice protects osteocytes and bone precursor cells against oxidative stress partly through SIRT1

Oxidative stress and abnormal osteocyte apoptosis are often related to dysregulation of bone turnover and chronic bone loss, and so fruit and vegetables with high antioxidant potential may play an important role in the prevention and/or management of osteoporosis. Osteocytes are the main regulators of bone remodelling. For the first time, we demonstrate here that blueberry juice (BJ), obtained from Vaccinium myrtillus, rich in polyphenols, shows antioxidant and antiosteoclastogenic properties in MLO‐Y4 osteocytes. We report that BJ prevents oxidative stress‐induced apoptosis and reverses the increase in receptor activator of nuclear factor κB ligand and sclerostin expression, crucial factors for osteoclast activation and bone resorption. BJ is also able to prevent oxidative stress‐induced cell cytotoxicity in bone marrow mesenchymal stromal cells (MSCs), which are considered to be an important tool for cell therapy in bone disorders. No significant difference in preventing these events was observed between BJ and blueberry dry extract containing equal amounts of total soluble polyphenols. We have also shown that blueberry acts as both an antioxidant and an activator of sirtuin type 1, a class III histone deacetylase involved in cell death regulation and considered a molecular target for blocking bone resorption without affecting osteoclast survival. Overall, these novel data obtained in osteocytes and MSCs may help us clarify the mechanisms by which blueberry counteracts oxidative stress‐induced damage in bone remodelling and osteogenesis at the cellular and molecular level. Our findings are consistent with the reported beneficial effects of blueberry on bone tissue reported in animal studies, which suggest that blueberry may be a useful supplement for the prevention and/or management of osteoporosis and osteogenic process.

Protective Effect of Hydrogen on Sodium Iodate-Induced Age-Related Macular Degeneration in Mice

Oxidative stress is one of the main causes of AMD. Hydrogen has anti-oxidative stress and apoptotic effects on retinal injury. However, the effect of hydrogen on AMD is not clear. In this study, fundus radiography, OCT, and FFA demonstrated that HRW reduced the deposition of drusen-like structures in RPE layer, prevented retina from thinning and leakage of ocular fundus vasculature induced by NaIO₃. ERG analysis confirmed that HRW effectively reversed the decrease of a-wave and b-wave amplitude in NaIO₃-mice. Mechanistically, HRW greatly reduced the oxidative stress reaction through decreased MDA levels, increased SOD production, and decreased ROS content. The OGG1 expression was downregulated which is a marker of oxidative stress. Involvement of oxidative stress was confirmed using oxidative stress inhibitor ALCAR. Moreover, oxidative stress reaction was associated with expression of Sirt1 level and HRW significantly inhibited the downregulation of Sirt1 expression. This result was further confirmed with AICAR which restore Sirt1 expression and activity. In addition, NaIO₃-induced retinal damage was related to apoptosis via caspase 8 and caspase 9, but not the caspase 3 pathways, which led to upregulation of Bax and p53, downregulation of Bcl-2, and increase in Jc-1-positive cells in mice. However, HRW effectively reversed these effects that apoptosis induced. These results suggest that HRW protects retinal functions against oxidative stress injury through inhibiting downregulation of Sirt1 and reducing retinal apoptosis. Therefore, we speculated that hydrogen administration is a promising treatment for AMD therapy.