The role of FOXO1-mediated autophagy in the regulation of bone formation

Effects of chloroquine and hydroxychloroquine on bone health (Review)

Chloroquine (CQ) and hydroxychloroquine (HCQ), which were initially used to treat malaria, are now also used to treat autoimmune and inflammatory diseases, which have gained notoriety during the coronavirus‑19 pandemic. The emerging uses of CQ and HCQ in cancer therapy, metabolic syndrome and bone disorders highlight their broad clinical potential. Patients with autoimmune and inflammatory conditions have a higher risk of suboptimal bone health because of chronic inflammation, immune dysregulation and medication use. In the present review, the use of CQ and HCQ in bone research was explored, particularly in terms of their effectiveness and mechanism in modulating bone homeostasis. CQ and HCQ inhibit osteoblastic activity by suppressing autophagy, inducing oxidative stress and promoting osteoblast apoptosis. CQ suppresses osteoclastic activity by blocking the receptor activator of nuclear factor κ‑β/receptor activator of nuclear factor κ‑β ligand interaction, autophagy and inflammation. HCQ inhibits osteoclastogenesis by increasing the expression levels of osteoprotegerin, inducing osteoclast apoptosis and reducing cytokines without affecting autophagy. With regard to the molecular machineries, CQ and HCQ inhibit bone formation and bone resorption. Variations in dose, frequency and duration of CQ and HCQ treatment result in heterogenous outcomes. Further research is necessary to clarify the net effects of CQ and HCQ on bone through studies specifically designed to explore their direct impact as the primary objective. The use of these medications is broadening particularly in patients with autoimmune diseases who are at risk of skeletal disorders. However, their safety profiles, adverse effects and contraindications must be carefully monitored when administered for long‑term use and in combination.

Functions and Therapeutic Potentials of Long Noncoding RNA in Skeletal Muscle Atrophy and Dystrophy

Skeletal muscle is the most abundant tissue in the human body and is responsible for movement, metabolism, energy production and longevity. Muscle atrophy is a frequent complication of several diseases and occurs when protein degradation exceeds protein synthesis. Genetics, ageing, nerve injury, weightlessness, cancer, chronic diseases, the accumulation of metabolic byproducts and other stimuli can lead to muscle atrophy. Muscular dystrophy is a neuromuscular disorder, part of which is caused by the deficiency of dystrophin protein and is mostly related to genetics. Muscle atrophy and muscular dystrophy are accompanied by dynamic changes in transcriptomic, translational and epigenetic regulation. Multiple signalling pathways, such as the transforming growth factor-β (TGF-β) signalling pathway, the phosphatidylinositol 3-kinase (PI3K)/protein kinase B (AKT)/mechanistic target of rapamycin (mTOR) pathway, inflammatory signalling pathways, neuromechanical signalling pathways, endoplasmic reticulum stress and glucocorticoids signalling pathways, regulate muscle atrophy. A large number of long noncoding RNAs (lncRNAs) have been found to be abnormally expressed in atrophic muscles and dystrophic muscles and regulate the balance of muscle protein synthesis and degradation or dystrophin protein expression. These lncRNAs may serve as potential targets for treating muscle atrophy and muscular dystrophy. In this review, we summarized the known lncRNAs related to muscular dystrophy and muscle atrophy induced by denervation, ageing, weightlessness, cachexia and abnormal myogenesis, along with their molecular mechanisms. Finally, we explored the potential of using these lncRNAs as therapeutic targets for muscle atrophy and muscular dystrophy, including the methods of discovery and clinical application prospects for functional lncRNAs.

USP11 promotes autophagy to attenuate LPS-induced oxidative stress in lung epithelial cells by stabilizing FOXO1 levels

BACKGROUND

Acute lung injury (ALI) is a critical condition characterized by severe inflammation and oxidative stress, leading to high morbidity and mortality. Despite advances in understanding ALI pathophysiology, effective treatment options remain limited. The increasing global burden of ALI, driven by factors such as infections, trauma, and environmental pollutants, emphasizes the urgent need for new therapeutic strategies. This study investigates the role of ubiquitin-specific protease 11 (USP11) in modulating Forkhead box protein O1 (FOXO1) to promote autophagy and alleviate oxidative stress in lung epithelial cells, which could provide novel insights into ALI therapeutic strategies.

MATERIALS AND METHODS

Bioinformatics were utilized to analyze the expression pattern of USP11 and FOXO1 in ALI, and their functions were detected based on gain- and loss-of function studies in vitro and in vivo. Besides, the effects of USP11 on FOXO1 stability and autophagy were examined through Western blot, immunofluorescence, and co-immunoprecipitation assays.

RESULTS

USP11 was found to be significantly downregulated in ALI, and its over-expression stabilized FOXO1, enhancing autophagy in lung epithelial cells. USP11 over-expression reduced oxidative stress and inflammatory cytokine production in vitro and in vivo. These results highlight the protective role of the USP11-FOXO1 axis in mitigating ALI pathophysiology.

CONCLUSIONS

This study identifies USP11 as a key regulator of FOXO1 and autophagy in ALI. The stabilization of FOXO1 through USP11 represents a promising therapeutic strategy for reducing oxidative stress and inflammation in ALI, warranting further clinical investigation.

PIK3R3 regulates differentiation and senescence of periodontal ligament stem cells and mitigates age-related alveolar bone loss by modulating FOXO1 expression

INTRODUCTION

Periodontal diseases are prevalent among middle-aged and elderly individuals. There's still no satisfactory solution for tooth loss caused by periodontal diseases. Human periodontal ligament stem cells (hPDLSCs) is a distinctive subgroup of mesenchymal stem cells, which play a crucial role in periodontal supportive tissues, but their application value hasn't been fully explored yet. As a regulatory subunit of PI3K, PIK3R3's role in stem cell regulation remains poorly comprehended.

OBJECTIVES

This study aims to explore the regulatory effect of PIK3R3 on differentiation and senescence of hPDLSCs and the underlying mechanism, as well as whether overexpression of PIK3R3 mitigate alveolar bone loss in aged rats.

METHODS

Human PDLSC lines with both PIK3R3 knockdown and overexpression are established. Osteogenic, adipogenic, chondrogenic and senescent induction are used to test the effect of PIK3R3 on senescence in vitro. Model of alveolar bone loss in aged mice is used to reveal the effect of PIK3R3 in vivo. FOXO1 siRNA is used for mechanism exploration.

RESULTS

Knockdown of PIK3R3 inhibits the mRNA and protein expression of markers in osteogenic, adipogenic, and chondrogenic differentiation of hPDLSCs but promotes in vitro senescence of hPDLSCs, including senescence markers expression, telomerase density and reactive oxygen species. Overexpression of PIK3R3 has the opposite effect. Furthermore, the result of Micro-CT and tissue section shows that overexpression of PIK3R3 in elder rats mitigates alveolar bone loss. Mechanistically, PIK3R3 regulates senescence of hPDLSCs through modulating FOXO1 expression. Expression of FOXO1 is altered when PIK3R3 is knocked down or overexpressed in senescent medium. Knockdown of FOXO1 promotes senescence of hPDLSCs and the senescence promoting effect of knocking down PIK3R3 is weakened when FOXO1 is highly expressed.

CONCLUSION

These findings indicate that PIK3R3 modulates senescence of hPDLSCs by regulating FOXO1 expression and shows promise as a therapeutic target for mitigating age-related alveolar bone loss.

Acetylation of FOXO1 is involved in cadmium-induced rat kidney injury via mediating autophagosome-lysosome fusion blockade and autophagy inhibition

Cadmium (Cd), a potentially toxic elements, has the potential to cause harm to the kidneys. Studies has demonstrated that autophagosome-lysosome fusion blockade and consequent autophagy inhibition is related to Cd-induced kidney injury. Studies indicate that acetylation of forkhead box protein O1 (FOXO1) as a transcriptional factor of lysosomal and autophagy genes, but its roles in Cd-exposed kidney tissues remains unclear till now. Therefore, the present study was conducted to elucidate this issue. Data found that Cd enhances the acetylation level of FOXO1 and inhibits the expression level of silent information regulator 1 (Sirt1, deacetylase of FOXO1). Pharmacological activation of Sirt1 (SRT2104 treatment) decreases Cd-increased acetylation level of FOXO1, enhances Cd-inhibited transcription level of Ras-related protein 7 (Rab7), restores Cd-blocked fusion of autophagosome and lysosome, and alleviates Cd-induced autophagy inhibition. Moreover, data corroborated that inhibiting the acetylation level of FOXO1 is conductive to mitigating Cd-induced kidney injury. Collectively, these results demonstrate that acetylation of FOXO1 mediates the autophagosome-lysosome fusion blockade and autophagy inhibition during Cd-induced kidney injury, while regulating the acetylation level of FOXO1 may be a potential mechanism of treating nephrotoxicity after Cd exposure.

Lycopene Promotes Osteogenesis and Reduces Adipogenesis through Regulating FoxO1/PPARγ Signaling in Ovariectomized Rats and Bone Marrow Mesenchymal Stem Cells

Recent interest in preventing the development of osteoporosis has focused on the regulation of redox homeostasis. However, the action of lycopene (LYC), a strong natural antioxidant compound, on osteoporotic bone loss remains largely unknown. Here, we show that oral administration of LYC to OVX rats for 12 weeks reduced body weight gain, improved lipid metabolism, and preserved bone quality. In addition, LYC treatment inhibited ROS overgeneration in serum and bone marrow in OVX rats, and in BMSCs upon H2O2 stimulation, leading to inhibiting adipogenesis and promoting osteogenesis during bone remodeling. At the molecular level, LYC improved bone quality via an increase in the expressions of FoxO1 and Runx2 and a decrease in the expressions of PPARγ and C/EBPα in OVX rats and BMSCs. Collectively, these findings suggest that LYC attenuates osteoporotic bone loss through promoting osteogenesis and inhibiting adipogenesis via regulation of the FoxO1/PPARγ pathway driven by oxidative stress, presenting a novel strategy for osteoporosis management.

Insights on E1-like enzyme ATG7: functional regulation and relationships with aging-related diseases

Autophagy is a dynamic self-renovation biological process that maintains cell homeostasis and is responsible for the quality control of proteins, organelles, and energy metabolism. The E1-like ubiquitin-activating enzyme autophagy-related gene 7 (ATG7) is a critical factor that initiates classic autophagy reactions by promoting the formation and extension of autophagosome membranes. Recent studies have identified the key functions of ATG7 in regulating the cell cycle, apoptosis, and metabolism associated with the occurrence and development of multiple diseases. This review summarizes how ATG7 is precisely programmed by genetic, transcriptional, and epigenetic modifications in cells and the relationship between ATG7 and aging-related diseases.

Acne Transcriptomics: Fundamentals of Acne Pathogenesis and Isotretinoin Treatment

This review on acne transcriptomics allows for deeper insights into the pathogenesis of acne and isotretinoin's mode of action. Puberty-induced insulin-like growth factor 1 (IGF-1), insulin and androgen signaling activate the kinase AKT and mechanistic target of rapamycin complex 1 (mTORC1). A Western diet (hyperglycemic carbohydrates and milk/dairy products) also co-stimulates AKT/mTORC1 signaling. The AKT-mediated phosphorylation of nuclear FoxO1 and FoxO3 results in their extrusion into the cytoplasm, a critical switch which enhances the transactivation of lipogenic and proinflammatory transcription factors, including androgen receptor (AR), sterol regulatory element-binding transcription factor 1 (SREBF1), peroxisome proliferator-activated receptor γ (PPARγ) and signal transducer and activator of transcription 3 (STAT3), but reduces the FoxO1-dependent expression of GATA binding protein 6 (GATA6), the key transcription factor for infundibular keratinocyte homeostasis. The AKT-mediated phosphorylation of the p53-binding protein MDM2 promotes the degradation of p53. In contrast, isotretinoin enhances the expression of p53, FoxO1 and FoxO3 in the sebaceous glands of acne patients. The overexpression of these proapoptotic transcription factors explains isotretinoin's desirable sebum-suppressive effect via the induction of sebocyte apoptosis and the depletion of BLIMP1(+) sebocyte progenitor cells; it also explains its adverse effects, including teratogenicity (neural crest cell apoptosis), a reduced ovarian reserve (granulosa cell apoptosis), the risk of depression (the apoptosis of hypothalamic neurons), VLDL hyperlipidemia, intracranial hypertension and dry skin.

The role of non-coding RNAs in diabetes-induced osteoporosis

Diabetes mellitus (DM) and osteoporosis are two major health care problems worldwide. Emerging evidence suggests that DM poses a risk for osteoporosis and can contribute to the development of diabetes-induced osteoporosis (DOP). Interestingly, some epidemiological studies suggest that DOP may be at least partially distinct from those skeletal abnormalities associated with old age or postmenopausal osteoporosis. The increasing number of DM patients who also have DOP calls for a discussion of the pathogenesis of DOP and the investigation of drugs to treat DOP. Recently, non-coding RNAs (ncRNAs) have received more attention due to their significant role in cellular functions and bone formation. It is worth noting that ncRNAs have also been demonstrated to participate in the progression of DOP. Meanwhile, nano-delivery systems are considered a promising strategy to treat DOP because of their cellular targeting, sustained release, and controlled release characteristics. Additionally, the utilization of novel technologies such as the CRISPR system has expanded the scope of available options for treating DOP. Hence, this paper explores the functions and regulatory mechanisms of ncRNAs in DOP and highlights the advantages of employing nanoparticle-based drug delivery techniques to treat DOP. Finally, this paper also explores the potential of ncRNAs as diagnostic DOP biomarkers.