SIRT1 Protects Against Oxidative Stress-Induced Endothelial Progenitor Cells Apoptosis by Inhibiting FOXO3a via FOXO3a Ubiquitination and Degradation

Relationship between arginine methylation and vascular calcification

In patients on maintenance hemodialysis (MHD), vascular calcification (VC) is an independent predictor of cardiovascular disease (CVD), which is the primary cause of death in chronic kidney disease (CKD). The main component of VC in CKD is the vascular smooth muscle cells (VSMCs). VC is an ordered, dynamic activity. Under the stresses of oxidative stress and calcium-‑phosphorus imbalance, VSMCs undergo osteogenic phenotypic transdifferentiation, which promotes the formation of VC. In addition to traditional epigenetics like RNA and DNA control, post-translational modifications have been discovered to be involved in the regulation of VC in recent years. It has been reported that the process of osteoblast differentiation is impacted by catalytic histone or non-histone arginine methylation. Its function in the osteogenic process is comparable to that of VC. Thus, we propose that arginine methylation regulates VC via many signaling pathways, including as NF-B, WNT, AKT/PI3K, TGF-/BMP/SMAD, and IL-6/STAT3. It might also regulate the VC-related calcification regulatory factors, oxidative stress, and endoplasmic reticulum stress. Consequently, we propose that arginine methylation regulates the calcification of the arteries and outline the regulatory mechanisms involved.

Exosomal hsa_circ_0093884 derived from endothelial progenitor cells promotes therapeutic neovascularization via miR-145/SIRT1 pathway

Therapeutic neovascularization is a strategy to promote blood vessel growth and improve blood flow, which is critical to tissue repair and regeneration in ischemic diseases. Here, we investigated the role of endothelial progenitor cell - derived exosomes (EPC-Exos) in therapeutic neovascularization and clarified the mechanism of hsa_circ_0093884 in EPC-Exos mediated neovascularization. Injection of EPC-Exos improved mouse ischemic hindlimb perfusion, promoted angiogenesis in Matrigel plugs and mouse skin wound healing. In vitro coculture with EPC-Exos improved HUVEC proliferation, angiogenic and migration ability, while alleviated hypoxia-induced apoptosis. hsa_circ_0093884 was identified from eleven types of circRNA derived from SIRT1 and proved to be enriched in EPC-Exos. Overexpression of hsa_circ_0093884 in EPC-Exos further enhanced the angiogenic capacity, while knockdown of hsa_circ_0093884 abolished the benefits. Mechanistically, EPC-Exos mediated shuttling of hsa_circ_0093884 induced cytoplasmic sponge of miR-145, thereby releasing repression of SIRT1. In vitro co-transfection indicated silence of miR-145 further strengthened the angiogenic effect of hsa_circ_0093884, while overexpression of miR-145 inhibited hsa_circ_0093884 mediated angiogenesis and abolished the beneficial effect of EPC-Exos. Furthermore, in vivo experiments using endothelial specific SIRT1 conditional knockout mice indicated hsa_circ_0093884 overexpressing EPC-Exos failed to promote therapeutic neovascularization in SIRT1cKO mice. Collectively, our results demonstrated that EPC-Exos promoted therapeutic neovascularization through hsa_circ_0093884/miR-145/SIRT1 axis.

Resveratrol Improves the Frozen-Thawed Ram Sperm Quality

Cryopreservation generates a substantial quantity of ROS in semen, leading to a decline in sperm quality and fertilization capacity. The objective of this study was to investigate the effects of resveratrol and its optimal concentration on ram sperm quality after cryopreservation. Ram semen was diluted with a freezing medium containing different concentrations of resveratrol (0, 25, 50, 75, and 100 μM). After thawing, various sperm parameters such as total motility, progressive motility, acrosome integrity, plasma membrane integrity, mitochondrial membrane potential, glutathione (GSH) content, glutathione synthase (GPx) activity, superoxide dismutase (SOD) activity, catalase (CAT) activity, lipid peroxidation (LPO) content, malondialdehyde (MDA) content, ROS level, SIRT1 level, DNA oxidative damage, and AMPK phosphorylation level were assessed. In addition, post-thaw sperm apoptosis was evaluated. Comparatively, the addition of resveratrol up to 75 μM significantly improved the sperm motility and sperm parameters of cryopreserved ram sperm. Specifically, 50 μM resveratrol demonstrated a notable enhancement in acrosome and plasma membrane integrity, antioxidant capacity, mitochondrial membrane potential, adenosine triphosphate (ATP) content, SIRT1 level, and AMPK phosphorylation levels compared to the control group (p < 0.05). It also significantly (p < 0.05) reduced the oxidative damage to sperm DNA. However, detrimental effects of resveratrol were observed at a concentration of 100 μM resveratrol. In conclusion, the addition of 50 μM resveratrol to the cryopreservation solution is optimal for enhancing the quality of cryopreserved ram sperm.

Further insights into the impact of rebamipide on gentamicin-induced nephrotoxicity in rats: modulation of SIRT1 and β-catenin/cyclin D1 pathways

Gentamicin (GM) is an effective antibiotic administered to treat acute Gram-negative infections. Nevertheless, its clinical application is limited due to nephrotoxicity. Therefore, our research aimed to investigate the potential renoprotective impact of rebamipide (RBM), a gastroprotective drug, on GM-induced kidney damage in rats, as well as putative nephroprotective pathways. RBM was orally administered (100 mg/kg/d for 14 d) commencing 7 d before the administration of GM (100 mg/kg/d, intraperitoneally). Nephrotoxicity was elucidated, and the silent information regulator 1 (SIRT1) and β-catenin/cyclin D1 pathways were assessed. GM induced a significant elevation in the serum levels of creatinine, blood urea nitrogen (BUN), and kidney injury molecule-1 (KIM-1), as well as the relative kidney index. In addition, GM increased lipid peroxidation and lowered total antioxidant capacity (TAC) level and superoxide dismutase (SOD) activity. GM administration also demonstrated a significant amplification in tumor necrosis factor-alpha (TNF-α), interleukin-1 beta (IL-1β), nuclear factor-κappa B p65 (NF-κB p65), p38 mitogen-activated protein kinase (p38 MAPK), and caspase-3 kidney levels, as well as B-cell lymphoma 2 (Bcl-2)-associated X protein (Bax)/Bcl-2 ratio. Notably, RBM treatment amended all these changes induced by GM. Furthermore, the potential role of SIRT1 and β-catenin-dependent signaling pathways in GM-induced renal injury was assessed. Our findings showed that GM-treated rats demonstrated a substantial decrease in SIRT1, nuclear factor E2-related factor 2 (Nrf2), and heme oxygenase-1 (HO-1) along with an increase in β-catenin, forkhead box O-3a (FOXO-3a), and cyclin D1 protein expressions. RMB treatment markedly attenuated the deterioration caused by GM on these pathways. Additionally, RBM alleviated the GM-induced deleterious kidney tissue histopathology. In conclusion, our findings have verified that RBM can halt GM-induced renal injury by partly modulating SIRT1 and β-catenin pathways.

Mitochondria in health, disease, and aging

Mitochondria are well known as organelles responsible for the maintenance of cellular bioenergetics through the production of ATP. Although oxidative phosphorylation may be their most important function, mitochondria are also integral for the synthesis of metabolic precursors, calcium regulation, the production of reactive oxygen species, immune signaling, and apoptosis. Considering the breadth of their responsibilities, mitochondria are fundamental for cellular metabolism and homeostasis. Appreciating this significance, translational medicine has begun to investigate how mitochondrial dysfunction can represent a harbinger of disease. In this review, we provide a detailed overview of mitochondrial metabolism, cellular bioenergetics, mitochondrial dynamics, autophagy, mitochondrial damage-associated molecular patterns, mitochondria-mediated cell death pathways, and how mitochondrial dysfunction at any of these levels is associated with disease pathogenesis. Mitochondria-dependent pathways may thereby represent an attractive therapeutic target for ameliorating human disease.

The cardioprotective effects of secoisolariciresinol diglucoside (flaxseed lignan) against cafeteria diet-induced cardiac fibrosis and vascular injury in rats: an insight into apelin/AMPK/FOXO3a signaling pathways

Introduction: Fast food is a major risk factor for atherosclerosis, a leading cause of morbidity and mortality in the Western world. Apelin, the endogenous adipokine, can protect against cardiovascular disease via activating its receptor, APJ. Concurrently, secoisolariciresinol diglucoside (SDG), a flaxseed lignan extract (FLE), showed a therapeutic impact on atherosclerosis. The current study aimed to examine the effect of SDG on cafeteria diet (CAFD)-induced vascular injury and cardiac fibrosis via tracking the involvement of the apelin/APJ pathway. Methods: Thirty male rats were allocated into control, FLE-, CAFD-, CAFD/FLE-, and CAFD/FLE/F13A-treated rats, where F13A is an APJ blocker. All treatments lasted for 12 weeks. Results and discussion: The CAFD-induced cardiovascular injury was evidenced by histological distortions, dyslipidemia, elevated atherogenic indices, cardiac troponin I, collagen percentage, glycogen content, and apoptotic markers. CAFD increased both the gene and protein expression levels of cardiac APJ, apelin, and FOXO3a, in addition to increasing endothelin-1, VCAM1, and plasminogen activator inhibitor-1 serum levels and upregulating cardiac MMP-9 gene expression. Moreover, CAFD reduced serum paraoxonase 1 and nitric oxide levels, cardiac AMPK, and nuclear Nrf2 expression. FLE attenuated CAFD-induced cardiovascular injury. Such effect was reduced in rats receiving the APJ blocker, implicating the involvement of apelin/APJ in FLE protective mechanisms. Conclusion: FLE supplementation abrogated CAFD-induced cardiac injury and endothelial dysfunction in an apelin/APJ-dependent manner.

The role of chromatin-modifying enzymes and histone modifications in the modulation of p16 gene in fumonisin B1-induced toxicity in human kidney cells

Fumonisin B₁ (FB₁) poses a risk to animal and human health. Although the effects of FB₁ on sphingolipid metabolism are well documented, there are limited studies covering the epigenetic modifications and early molecular alterations associated with carcinogenesis pathways caused by FB₁ nephrotoxicity. The present study investigates the effects of FB₁ on global DNA methylation, chromatin-modifying enzymes, and histone modification levels of the p16 gene in human kidney cells (HK-2) after 24 h exposure. An increase (2.23-fold) in the levels of 5-methylcytosine (5-mC) at 100 µmol/L was observed, a change independent from the decrease in gene expression levels of DNA methyltransferase 1 (DNMT1) at 50 and 100 µmol/L; however, DNMT3a and DNMT3b were significantly upregulated at 100 µmol/L of FB₁. Dose-dependent downregulation of chromatin-modifying genes was observed after FB₁ exposure. In addition, chromatin immunoprecipitation results showed that 10 µmol/L of FB₁ induced a significant decrease in H3K9ac, H3K9me3 and H3K27me3 modifications of p16, while 100 µmol/L of FB₁ caused a significant increase in H3K27me3 levels of p16. Taken together, the results suggest that epigenetic mechanisms might play a role in FB₁ carcinogenesis through DNA methylation, and histone and chromatin modifications.

Luteolin inhibits triple-negative breast cancer by inducing apoptosis and autophagy through SGK1-FOXO3a-BNIP3 signaling

Background: Triple-negative breast cancer (TNBC) is one of the most prominent neoplasm disorders and lacks efficacious treatments yet. Luteolin (3',4',5,7-tetrahydroxyflavone), a natural flavonoid commonly presented in plants, has been reported to delay the progression of TNBC. However, the precise mechanism is still elusive. We aimed to elucidate the inhibition and molecular regulation mechanism of luteolin on TNBC. Methods: The effects of luteolin on the biological functions of TNBC cells were first evaluated using the corresponding assays for cell counting kit-8 assay, flow cytometry, wound-healing assay, and transwell migration assay, respectively. The mechanism of luteolin on TNBC cells was then analyzed by RNA sequencing and verified by RT-qPCR, Western blot, transmission electron microscopy, etc. Finally, in vivo mouse tumor models were constructed to further confirm the effects of luteolin on TNBC. Results: Luteolin dramatically suppressed cell proliferation, invasion, and migration while favoring cell apoptosis in a dose- and time-dependent manner. In TNBC cells treated with luteolin, SGK1 and AKT3 were significantly downregulated while their downstream gene BNIP3 was upregulated. According to the results of 3D modeling, the direct binding of luteolin to SGK1 was superior to that of AKT3. The inhibition of SGK1 promoted FOXO3a translocation into the nucleus and led to the transcription of BNIP3 both in vitro and in vivo, eventually facilitating the interaction between BNIP3 and apoptosis and autophagy protein. Furthermore, the upregulation of SGK1, induced by luteolin, attenuated the apoptosis and autophagy of the TNBC. Conclusion: Luteolin inhibits TNBC by inducing apoptosis and autophagy through SGK1-FOXO3a-BNIP3 signaling.

Acute valproate exposure affects proneural factor expression by increasing FOXO3 in the hippocampus of juvenile mice with a sex-based difference

Valproic acid (VPA), an anticonvulsant and mood stabilizer, may affect Notch signaling and mitochondrial function. In a previous study, acute VPA exposure induced increased expression of FOXO3, a transcription factor that shares common targets with pro-neuronal ASCL1. In this study, intraperitoneal acute VPA (400 mg/kg) administration in 4-week-old mice increased and decreased FOXO3 and ASCL1 expression, respectively, in the hippocampus, associated with sex-based differences. Treatment of Foxo3 siRNA increased the mRNA expression levels of Ascl1, Ngn2, Hes6, and Notch1 in PC12 cells. Furthermore, VPA exposure induced significant expression changes of mitochondria-related genes, including COX4 and SIRT1, in hippocampal tissues, associated with sex-based differences. This study suggests that acute VPA exposure differently affects proneural gene expression via FOXO3 induction in the hippocampus based on sex.

Contribution of microRNA-30d to the prevention of the thyroid cancer occurrence and progression: mechanism and implications

Thyroid cancer is a major endocrine tumor and represents an emerging health problem worldwide. MicroRNAs (miRNAs) have been addressed to participate in the pathogenesis and progression of thyroid cancer. However, it remains largely unknown what functions miR-30d may exert on thyroid cancer. This study, herein, aimed to identify the functional significance and machinery of miR-30d in the progression of thyroid cancer. MiR-30b presented aberrant low expression and ubiquitin-specific protease 22 (USP22) exhibited aberrant high expression in thyroid cancer tissues and cells. The current study proposed the possible machinery that miR-30d could target and negatively regulate USP22. Additionally, USP22 could enhance the stability of SIRT1 by inducing deubiquitination which consequently contributed to FOXO3a deacetylation-induced PUMA repression. Responding to the gain- or loss-of-function of miR-30d and/or USP22, behaviors of thyroid cancer cells were altered. Accordingly, miR-30d inhibited proliferation and promoted apoptosis of thyroid cancer cells by suppressing USP22 through SIRT1/FOXO3a/PUMA axis. The effects of miR-30d and USP22-mediated SIRT1/FOXO3a/PUMA axis on thyroid tumorigenesis were finally validated in murine models. We ultimately confirmed the anti-proliferative and pro-apoptotic effect of miR-30d via suppressing USP22 through in vivo findings. Conclusively, our findings highlight that the occurrence and progression of thyroid cancer can be suppressed by miR-30d-mediated inhibition of USP22 via the SIRT1/FOXO3a/PUMA axis, which provides a attractive therapeutic target for thyroid cancer treatment.

Regulation of radiation-induced liver damage by modulation of SIRT-1 activity: In vivo rat model

Silent information regulator 1 (SIRT-1), a nicotinamide adenine dinucleotide-dependent deacetylase, was found to regulate cell apoptosis, inflammation, and oxidative stress response in living organisms. Therefore, the role of SIRT-1 in regulating forkhead box O/poly ADP-ribose polymerase-1 (FOXO-1/PARP-1) signaling could provide the necessary validation for developing new pharmacological targets for the promotion or inhibition of SIRT-1 activity toward radiation sensitivity. In the present study, the SIRT-1 signaling pathway is being investigated to study the possible modulatory effect of resveratrol (RSV, SIRT-1 activator) versus nicotinamide (NAM, SIRT-1 inhibitor) in case of liver damage induced by whole-body gamma irradiation. Rats were exposed to 6 Gy gamma radiation after being pretreated with either RSV (10 mg/kg/day) or NAM (100 mg/kg/day) for 5 days, and subsequent examining hepatic morphological changes and apoptotic markers were assessed. The expression of SIRT-1, FOXO-1, and cleaved PARP-1 in the liver was analyzed. RSV improved radiation-induced apoptosis, mitochondrial dysfunction, and inflammation signified by low expression of caspase-3, lactate dehydrogenase, complex-I activity, myeloperoxidase, and total nitric oxide content. RSV increased the expression of SIRT-1, whereas cleaved PARP-1 and FOXO-1 were suppressed. These protective effects were suppressed by inhibition of SIRT-1 activity using NAM. These findings suggest that RSV can attenuate radiation-induced hepatic injury by reducing apoptosis and inflammation via SIRT-1 activity modulation.

Combination of EPC-EXs and NPC-EXs with miR-126 and miR-210 overexpression produces better therapeutic effects on ischemic stroke by protecting neurons through the Nox2/ROS and BDNF/TrkB pathways

BACKGROUNDS/AIMS

Neural progenitor cells (NPCs) and endothelial progenitor cell (EPCs) exhibit synergistical effects on protecting endothelial cell functions. MiR-126 and miR-210 can protect cell activities by regulating brain-derived neurotrophic factor (BDNF) and reactive oxygen species (ROS) production. Exosomes (EXs) mediate the beneficial effects of stem cells via delivering microRNAs (miRs). Here, we investigated the combination effects of EXs from EPCs (EPC-EXs) and NPCs (NPC-EXs), and determined whether these EXs with miR-126 (EPC-EXs^miR-126) and miR-210 overexpression (NPC-EXs^miR-210) had better effects on hypoxia/reoxygenation (H/R)-injured neurons and ischemic stroke (IS).

METHODS

Cultured neurons were subjected to hypoxia for 6 h and then co-cultured with culture medium, NPC-EXs, EPC-EXs, NPC-EXs + EPC-EXs or NPC-EXs^miR-210 + EPC-EXs^miR-126 under normoxia for 24 h. Cell apoptosis, ROS production, neurite outgrowth and BDNF level were analyzed. Permanent middle cerebral artery occlusion (MCAO) was performed on C57BL/6 mice to build IS model. The mice were injected with PBS or various EXs via tail vein 2 h after MCAO operation. After 24 h, infarct volume and neurological deficits score (NDS), neuronal apoptosis, ROS production and spine density of dendrites, and brain BDNF level were analyzed. For mechanism study, NADPH oxidase 2(Nox2) and BDNF receptor tyrosine kinase receptor B (TrkB) were determined, and TrkB inhibitor k-252a was used in in vitro and in vivo study.

RESULTS

1) The level of miR-210 or miR-126 was increased after NPC-EXs or EPC-EXs treatment respectively. 2) In H/R-injured neurons, NPC-EXs or EPC-EXs decreased cell apoptosis and ROS production and promoted neurite outgrowth, which were associated with the downregulation of Nox2 and the increase of BDNF and p-TrkB/TrkB level. 3) In MCAO mice, NPC-EXs or EPC-EXs decreased infarct volume and NDS, reduced neural apoptosis and ROS production, and promoted the spine density of dendrites. The levels of Nox2, BDNF and p-TrkB/TrkB in mouse brain tissues changed in similar patterns as seen in the in vitro study. 4) In both cell and mouse models, combination of NPC-EXs and EPC-EXs was more effective than NPC-EXs or EPC-EXs alone on all of these effects. 5) EPC-EXs^miR-126 + NPC-EXs^miR-210 had better effects compared to NPC-EXs + EPC-EXs, which were inhibited by k-252a.

CONCLUSION

EPC-EXs^miR-126 combined NPC-EXs^miR-210 further orchestrate the combinative protective effects of EPC-EXs and NPC-EXs on IS, possibly by protecting H/R-injured neurons through the Nox2/ ROS and BDNF/TrkB pathways.

Role of FOXO3a Transcription Factor in the Regulation of Liver Oxidative Injury

Oxidative stress has been identified as a key mechanism in liver damage caused by various chemicals. The transcription factor FOXO3a has emerged as a critical regulator of redox imbalance. Multiple post-translational changes and epigenetic processes closely regulate the activity of FOXO3a, resulting in synergistic or competing impacts on its subcellular localization, stability, protein-protein interactions, DNA binding affinity, and transcriptional programs. Depending on the chemical nature and subcellular context, the oxidative-stress-mediated activation of FOXO3a can induce multiple transcriptional programs that play crucial roles in oxidative injury to the liver by chemicals. Here, we mainly review the role of FOXO3a in coordinating programs of genes that are essential for cellular homeostasis, with an emphasis on exploring the regulatory mechanisms and potential application of FOXO3a as a therapeutic target to prevent and treat liver oxidative injury.

The expression of Sirt1/FoxO1 pathway in the placenta of patients with preeclampsia and its connection with prognosis

This study aimed to analyse the expression of Sirt1/FoxO1 pathway in the placenta of patients with preeclampsia (PE). Clinical data of 111 PE patients were retrospectively analysed and divided into mild group (n = 61) and severe group (n = 50) according to the severity of condition. Another 45 healthy mothers were selected as healthy group. The value of Sirt1/FoxO1 pathway-related proteins in predicting prognosis of PE patients was analysed. The severe group had higher Sirt1 and lower FoxO1 protein expressions than the mild and healthy groups (p < 0.05). Sirt1 protein expression was positively correlated with ROS, LHP, NOX4, IL-1β, IL-6, HMGB1, CRP, VCAM-1, Caspase-3, Fas, Apaf-1 and ET-1 in PE patients (r > 0, p < 0.05), while FoxO1 protein expression was negatively correlated with these indices (r < 0, p < 0.05). Sirt1 protein expression was negatively correlated with SOD, CAT, GSH-Px, Bcl-2, Mcl-2, P57_kip2 and NO (r < 0, p < 0.05), while FoxO1 protein expression was positively correlated with these indices (r > 0, p < 0.05). The expression of Sirt1/FoxO1 pathway related proteins was abnormal in placenta of PE patients, and was closely related to the expression of oxidative stress, inflammatory response, endothelial damage factors and apoptotic molecules.IMPACT STATEMENTWhat is already known on this subject? The Sirt1/FoxO1 pathway is abnormally expressed in the placenta of preeclampsia patients, with Sirt1 protein expression up-regulated and FoxO1 protein expression down-regulated, both of which are closely related to the expression of oxidative stress, inflammatory response, endothelial damage factors and apoptotic molecules in the placenta of preeclampsia patients.What do the results of this study add? The results of this study add to the knowledge about the role of the Sirt1/FoxO1 pathway in the pathogenesis of preeclampsia.What are the implications of these findings for clinical practice and/or further research? These findings provide a basis for predicting poor pregnancy outcomes in patients with preeclampsia in clinical practice.

Sirt1 attenuates astrocyte activation via modulating Dnajb1 and chaperone-mediated autophagy after closed head injury

Our previous study indicates that Silent information regulator 1 (Sirt1) is involved in macroautophagy by upregulating light chain 3 (LC3) expression in astrocyte to exert a neuroprotective effect. Chaperon-mediated autophagy (CMA), another form of autophagy, is also upregulated after brain injury. However, little is known about the role of Sirt1 in regulation of the CMA. In the present study, an in vivo model of closed head injury (CHI) and an in vitro model of primary cortical astrocyte stimulated with interleukin-1β were employed to mimic the astrocyte activation induced by traumatic brain injury. Lentivirus carrying target complementary DNA (cDNA) or short hairpin RNA (shRNA) sequence was used to overexpress Sirt1 or knockdown DnaJ heat shock protein family member B1 (Dnajb1) (a molecular chaperone). We found that Sirt1 overexpression ameliorated neurological deficits, reduced tissue loss, and attenuated astrocyte activation after CHI, which was reversed by Dnajb1-shRNA administration. The upregulation of CMA activity induced by CHI in vivo and in vitro was inhibited after Dnajb1 knockdown. Sirt1 potently promoted CMA activity via upregulating Dnajb1 expression. Mechanically, Sirt1 could interact with Dnajb1 and modulate the deacetylation and ubiquitination of Dnajb1. These findings collectively suggest that Sirt1 plays a protective role against astrocyte activation, which may be associated with the regulation of the CMA activity via modulating the deacetylation and ubiquitination of Dnajb1 after CHI.

The Role of Forkhead Box O in Pathogenesis and Therapy of Diabetes Mellitus

Type 2 diabetes is a disease that causes numerous complications disrupting the functioning of the entire body. Therefore, new treatments for the disease are being sought. Studies in recent years have shown that forkhead box O (FOXO) proteins may be a promising target for diabetes therapy. FOXO proteins are transcription factors involved in numerous physiological processes and in various pathological conditions, including cardiovascular diseases and diabetes. Their roles include regulating the cell cycle, DNA repair, influencing apoptosis, glucose metabolism, autophagy processes and ageing. FOXO1 is an important regulator of pancreatic beta-cell function affecting pancreatic beta cells under conditions of insulin resistance. FOXO1 also protects beta cells from damage resulting from oxidative stress associated with glucose and lipid overload. FOXO has been shown to affect a number of processes involved in the development of diabetes and its complications. FOXO regulates pancreatic β-cell function during metabolic stress and also plays an important role in regulating wound healing. Therefore, the pharmacological regulation of FOXO proteins is a promising approach to developing treatments for many diseases, including diabetes mellitus. In this review, we describe the role of FOXO proteins in the pathogenesis of diabetes and the role of the modulation of FOXO function in the therapy of this disease.

DL-3-N-Butylphthalide Promotes Cartilage Extracellular Matrix Synthesis and Inhibits Osteoarthritis Development by Regulating FoxO3a

Osteoarthritis (OA) has been reported as a progressive disease in the elderly, primarily characterized by degenerated articular cartilage. There has been no satisfactory drug for the treatment of OA. DL-3-n-butylphthalide (NBP), a small molecule compound extracted from celery seeds, may have antiapoptotic, antioxidant, and anti-inflammatory activities in numerous studies. However, the effects of NBP on OA and its mechanisms have been rarely reported. In this study, the effect of NBP on OA in vitro and in vivo and its possible mechanism were investigated. The results showed that NBP injection into the knee joint inhibited osteoarthritis development in a rat model of osteoarthritis induced by DMM+ACLT. NBP could increase the expressions of extracellular matrix-related components (such as type II collagen, aggrecan, proteoglycan 4, and SRY-box 9) in human osteoarthritic chondrocytes and cartilage explants. Moreover, NBP promoted the expressions of SOD and CAT. NBP upregulated the expression of FoxO3a by inhibiting the PI3K/AKT pathway, which subsequently inhibited the apoptosis of human OA chondrocytes. In conclusion, NBP promotes cartilage extracellular matrix synthesis and inhibits osteoarthritis development and the underlying mechanism related to the activation of FoxO3a.

Pharmacological Approaches to Decelerate Aging: A Promising Path

Biological aging or senescence is a course in which cellular function decreases over a period of time and is a consequence of altered signaling mechanisms that are triggered in stressed cells leading to cell damage. Aging is among the principal risk factors for many chronic illnesses such as cancer, cardiovascular disorders, and neurodegenerative diseases. Taking this into account, targeting fundamental aging mechanisms therapeutically may effectively impact numerous chronic illnesses. Selecting ideal therapeutic options in order to hinder the process of aging and decelerate the progression of age-related diseases is valuable. Along therapeutic options, life style modifications may well render the process of aging. The process of aging is affected by alteration in many cellular and signaling pathways amid which mTOR, SIRT1, and AMPK pathways are the most emphasized. Herein, we have discussed the mechanisms of aging focusing mainly on the mentioned pathways as well as the role of inflammation and autophagy in aging. Moreover, drugs and natural products with antiaging properties are discussed in detail.

Autophagy-Sirtuin1(SIRT1) Alleviated the Coronary Atherosclerosis (AS)in Mice through Regulating the Proliferation and Migration of Endothelial Progenitor Cells (EPCs) via wnt/β-catenin/GSK3β Signaling Pathway

BACKGROUND AND PURPOSE

SIRT1 was associated with AS risk and EPCs were reported to participate in the endothelial repair in Coronary Atherosclerosis (CAS). In this study, we explored the role of SIRT1 in AS mice and also its modulation in EPCs.

METHODS AND MATERIALS

ApoE-/-mice were fed on high-fat and high-glucose diet to establish the AS animal model with the normally-raised C57BL/6 mice as a control group. SIRT1 activator, SRT 2104 was injected intravenously into 5 ApoE-/-mice and its inhibitor Nicotinamide was injected in tail in another 5 ApoE-/-mice. Weight changes were recorded. Blood samples were taken from posterior orbital venous plexus and were detected by automatic biochemical analyzer. HE staining displayed the pathological conditions while Immunohistochemistry (IHC) evaluated the CD34+/VEGFR2+ relative density in the aorta tissues. EPCs were isolated from bone marrow and verified using immunofluorescence staining (IFS). The modulatory mechanism of SIRT1 in EPCs were studied by using RT-PCR, MTT, Western Blot and colony formation, scratch methods.

RESULTS

SIRT1 activator negatively regulated the weight and TC, TG and LDL levels, alleviated the lesion conditions and decreased the CD34+/VEGFR2+ density compared to the AS control. In vitro, SIRT1 activator promoted the proliferation and migration of EPCs and activated wnt/β-catenin/GSK3β signaling pathway. SIRT1 activator also inhibited the autophagy biomarkers ATG1 and LC3II. Furthermore, inhibitor of autophagy promoted SIRT1 expression and induced EPC proliferation, migration and activated wnt/β-catenin/GSK3β pathway. The suppression of the wnt/β-catenin/GSK3β pathway inhibited SIRT1 expression in EPCs, attenuated the proliferation and migration and promoted autophagy of EPCs.

CONCLUSION

SIRT1 activation might be protective in AS mice through autophagy inhibition in EPCs via wnt/β-catenin/GSK3β signaling pathway.

NKT-like (CD3 + CD56+) cells differ from T cells in expression level of cellular protective proteins and sensitivity to stimulation in the process of ageing

BACKGROUND

NKT-like cells are T lymphocytes coexpressing several NK cell-associated receptors. They are effector lymphocytes of innate and adaptive immunity, and their number increases with age. The study aimed to analyze the expression of cellular protective proteins, i.e. sirtuin 1 (SIRT1), heat shock protein 70 (HSP70) and manganese superoxide dismutase (SOD2) in NKT-like and T cells of the young ('young', 31 subjects, age range 19-24 years), seniors aged under 85 ('old'; 30 subjects, age range 65-84 years) and seniors aged over 85 ('oldest', 24 subjects, age range 85-94 years). Both NKT-like and T cells were cultured for 48 h and stimulated with IL-2, LPS and PMA with ionomycin and compared with unstimulated control cells.

RESULTS

The oldest seniors varied from the other age groups by significantly increased expression of SIRT1 and HSP70 in both NKT-like and T cells observed in both stimulated and nonstimulated cells. The analyzed lymphocyte populations of the oldest revealed not only the highest expression of these proteins but also insensitivity to all types of applied stimulation. When NKT-like cells were compared to T cells, higher expression of the studied protective proteins was observed in both stimulated and unstimulated NKT-like cells. Neither CD3 + CD56+ nor CD3+ cells revealed elevated expression of SOD2, and these cells responded to stimulation until very advanced age. T cells revealed higher sensitivity to stimulation with IL-2 regarding SIRT1 and HSP70 expression. NKT-like cells were more sensitive to stimulation with PMA and ionomycin concerning the expression of these proteins. IL-2 did not induce a significant increase in SOD2 expression in the studied age groups.

CONCLUSIONS

The oldest seniors developed an adaptive stress response in both T and NKT-like cells regarding the expression of SIRT1 and HSP70, which was increased and insensitive to further stimulation in contrast to SOD2, which showed a more inducible pattern of expression. CD3 + CD56+ cells exhibited higher expression of cellular protective proteins than CD3+ cells in both stimulated and control, nonstimulated cells. NKT-like and T cells showed a distinct sensitivity to the applied stimulatory factors in the respective age groups.

Estradiol initiates the immune escape of non-small cell lung cancer cells via ERβ/SIRT1/FOXO3a/PD-L1 axis

Mounting evidence has postulated estrogen as a contributor for lung cancer development and progression. Here, we focused on the effect of estradiol (E2) on the immune escape of non-small cell lung cancer (NSCLC). The expression of FOXO3a in NSCLC samples was screened by gene microarray and then verified using Western blot analysis in NSCLC cell lines. Interaction between E2, SIRT1, FOXO3a and PD-L1 was determined. Following ectopic expression and depletion experiments in A549 and H1435 cells, cell proliferation and killing of cytotoxic T lymphocytes (CTLs) on NSCLC cells were evaluated. Xenograft mouse models were prepared to validate the in vivo effect of E2. E2 activated SIRT1 by up-regulating the expression of ERβ and thereby weakened the killing of CTLs on NSCLC cells. E2 elevated PD-L1 by up-regulating the ERβ/SIRT1 axis to promote the immune escape of NSCLC cells. SIRT1 degraded FOXO3a by reducing the acetylation level of FOXO3a and increased its ubiquitination. E2 inhibited the expression of FOXO3a and elevated PD-L1 expression, thereby promoting the immune escape of NSCLC cells. In vivo results showed that E2 facilitated the growth and metastasis of NSCLC cells in nude mice by elevating ERβ via SIRT1/FOXO3a/PD-L1 axis. In summary, our data revealed the critical roles of E2/ERβ/SIRT1/FOXO3a/PD-L1 axis in the immune escape of NSCLC cells and suggested that the axis may be promising therapeutic targets for NSCLC.

MiRNA-124-3p.1 sensitizes hepatocellular carcinoma cells to sorafenib by regulating FOXO3a by targeting AKT2 and SIRT1

As a multikinase inhibitor, sorafenib is commonly used to treat patients with advanced hepatocellular carcinoma (HCC), however, acquired resistance to sorafenib is a major obstacle to the effectiveness of this treatment. Thus, in this study, we investigated the mechanisms underlying sorafenib resistance as well as approaches devised to increase the sensitivity of HCC to sorafenib. We demonstrated that miR-124-3p.1 downregulation is associated with early recurrence in HCC patients who underwent curative surgery and sorafenib resistance in HCC cell lines. Regarding the mechanism of this phenomenon, we identified FOXO3a, an important cellular stress transcriptional factor, as the key factor in the function of miR-124-3p.1 in HCC. We showed that miR-124-3p.1 binds directly to AKT2 and SIRT1 to reduce the levels of these proteins. Furthermore, we showed that AKT2 and SIRT1 phosphorylate and deacetylate FOXO3a. We also found that miR-124-3p.1 maintains the dephosphorylation and acetylation of FOXO3a, leading to the nuclear location of FOXO3a and enhanced sorafenib-induced apoptosis. Moreover, the combination of miR-124-3p.1 mimics and sorafenib significantly enhanced the curative efficacy of sorafenib in a nude mouse HCC xenograft model. Collectively, our data reveal that miR-124-3p.1 represents a predictive indicator of early recurrence and sorafenib sensitivity in HCC. Furthermore, we demonstrate that miR-124-3p.1 enhances the curative efficacy of sorafenib through dual effects on FOXO3a. Thus, the miR-124-3p.1-FOXO3a axis is implicated as a potential target for the diagnosis and treatment of HCC.

A comprehensive insight into autophagy and its potential signaling pathways as a therapeutic target in podocyte injury

As part of the glomerular filtration membrane, podocyte is terminally differentiated, structurally unique, and highly specialized in maintaining kidney function. Proteinuria caused by podocyte injury (foot process effacement) is the clinical symptom of various kidney diseases (CKD), including nephrotic syndrome. Podocyte autophagy has become a powerful therapeutic strategy target in ameliorating podocyte injury. Autophagy is known to be associated significantly with sirtuin-1, proteinuria, and podocyte injury. Various key findings in podocyte autophagy were reported in the past ten years, such as the role of endoplasmic reticulum (ER) stress in podocyte autophagy impairment, podocyte autophagy-related gene, essential roles of the signaling pathways: Mammalian Target of Rapamycin (mTOR)/ Phosphoinositide 3-kinase (PI3k)/ serine/threonine kinase 1 (Akt) in podocyte autophagy. These significant factors caused podocyte injury associated with autophagy impairment. Sirtuin-1 was reported to have a vital key role in mTOR signaling, 5'AMP-activated protein kinase (AMPK) regulation, autophagy activation, and various critical pathways associated with podocyte's function and health; it has potential value to podocyte injury pathogenesis investigation. From these findings, podocyte autophagy has become an attractive therapeutic strategy to ameliorate podocyte injury, and this review will provide an in-depth review on therapeutic targets he podocyte autophagy.

SIRT1-mediated deacetylation of FOXO3a transcription factor supports pro-angiogenic activity of interferon-deficient tumor-associated neutrophils

Angiogenesis plays an important role during tumor growth and metastasis. We could previously show that Type I interferon (IFN)-deficient tumor-associated neutrophils (TANs) show strong pro-angiogenic activity, and stimulate tumor angiogenesis and growth. However, the exact mechanism responsible for their pro-angiogenic shift is not clear. Here, we set out to delineate the molecular mechanism and factors regulating pro-angiogenic properties of neutrophils in the context of Type I IFN availability. We demonstrate that neutrophils from IFN-deficient (Ifnar1^-/- ) mice efficiently release pro-angiogenic factors, such as VEGF, MMP9 or BV8, and thus significantly support the vascular normalization of tumors by increasing the maturation of perivascular cells. Mechanistically, we could show here that the expression of pro-angiogenic factors in neutrophils is controlled by the transcription factor forkhead box protein O3a (FOXO3a), which activity depends on its post-translational modifications, such as deacetylation or phosphorylation. In TANs isolated from Ifnar1^-/- mice, we observe significantly elevated SIRT1, resulting in SIRT1-mediated deacetylation of FOXO3a, its nuclear retention and activation. Activated FOXO3a supports in turn the transcription of pro-angiogenic genes in TANs. In the absence of SIRT1, or after its inhibition in neutrophils, elevated kinase MEK/ERK and PI3K/AKT activity is observed, leading to FOXO3a phosphorylation, cytoplasmic transfer and inactivation. In summary, we have found that FOXO3a is a key transcription factor controlling the angiogenic switch of neutrophils. Post-translational FOXO3a modifications regulate its transcriptional activity and, as a result, the expression of pro-angiogenic factors supporting development of vascular network in growing tumors. Therefore, targeting FOXO3a activity could provide a novel strategy of antiangiogenic targeted therapy for cancer.

Interplay between oxidative stress, SIRT1, reproductive and metabolic functions

Silent information Regulators (SIRT1) gene stimulates antioxidants' expression, repairs cells damaged by oxidative stress (OS), and prevents the cells' dysfunction. In particular, the role of different Sirtuins, particularly SIRT1 in reproduction, has been widely studied over the past decade. Decreased SIRT 1 causes mitochondrial dysfunction by increasing Reactive Oxygen Species (ROS), lipid peroxidation, and DNA damage in both male and female gametes (Sperms and Oocytes), leading to infertility. In the female reproductive system, SIRT1 regulates proliferation and apoptosis in granulosa cells (GCs), and its down-regulation is associated with a reduced ovarian reserve. SIRT1 also modulates the stress response to OS in GCs by targeting a transcription factor vital for ovarian functions and maintenance. ROS-mediated damage to spermatozoa's motility and morphology is responsible for 30-80% of men's infertility cases. High levels of ROS can cause damage to deoxyribo nucleic acid (DNA) in the nucleus and mitochondria, lipid peroxidation, apoptosis, inactivation of enzymes, and oxidation of proteins in spermatozoa. SIRT 1 is a cardioprotective molecule that prevents atherosclerosis by modulating various mechanisms such as endothelial injury due to impaired nitric oxide (NO) production, inflammation, OS, and regulation of autophagy. SIRT 1 is abundantly expressed in tubular cells and podocytes. It is also found to be highly expressed in aquaporin 2 positive cells in the distal nephron suggesting its involvement in sodium and water handling. SIRT1 improves insulin resistance by reducing OS and regulating mitochondrial biogenesis and function. It also decreases adiposity and lipogenesis and increases fatty acid oxidation. So, its involvement in the multiple pathways ensures its unique role in reproductive and metabolic derangement mechanisms.

5,7,3',4'-tetramethoxyflavone ameliorates cholesterol dysregulation by mediating SIRT1/FOXO3a/ABCA1 signaling in osteoarthritis chondrocytes

Dyslipidemia has been associated with the development of osteoarthritis. Our previous study found that 5,7,3',4'-tetramethoxyflavone (TMF) exhibited protective activities against the pathological changes of osteoarthritis. Aim: To investigate the roles of TMF in regulating ABCA1-mediated cholesterol metabolism. Methods: Knockdown and overexpression were employed to study gene functions. Protein-protein interaction was investigated by co-immunoprecipitation, and the subcellular locations of proteins were studied by immunofluorescence. Results: IL-1β decreased ABCA1 expression and induced apoptosis. Therapeutically, TMF ameliorated the effects of IL-1β. FOXO3a knockdown expression abrogated the effects of TMF, and FOXO3a overexpression increased ABCA1 expression by interacting with LXRα. TMF promoted FOXO3a nuclear translocation by activating SIRT1 expression. Conclusions: TMF ameliorates cholesterol dysregulation by increasing the expression of FOXO3a/LXRα/ABCA1 signaling through SIRT1 in C28/I2 cells.

NF-κB inducible miR-30b-5p aggravates joint pain and loss of articular cartilage via targeting SIRT1-FoxO3a-mediated NLRP3 inflammasome

MicroRNAs (miRNAs) contribute to osteoarthritis (OA) development. Nevertheless, the function and mechanism of miR-30b-5p in OA are unclear. In the present article, we gauged the miR-30b-5p level in OA patients and analyzed its correlation with OA stages. Then, we conducted in-vivo and in-vitro gain-of-function assays to determine the function of miR-30b-5p, silent information regulator 2 homolog 1 (SIRT1) and Fox. Cell counting Kit-8 (CCK-8) assay, BrdU assay and flow cytometry were utilized to gauge cell viability and apoptosis of human chondrocyte (HC-A). The targeting association between miR-30b-5p and SIRT1 was validated through the dual-luciferase reporter assay and RNA immunoprecipitation (RIP) experiment. The results signified that miR-30b-5p was up-regulated in OA patients, OA rats and interleukin-1β (IL-1β)-induced chondrocytes. The higher miR-30b-5p expression brought about progressive stages of OA patients and enhanced levels of pro-inflammatory mediators in the synovial fluid. Functionally, overexpressing miR-30b-5p hampered cell viability, aggravated chondrocyte apoptosis and NLRP3 inflammasome activation induced by IL-1β, while down-regulating miR-30b-5p exerted the reverse effects. The in-vivo experiment exhibited that down-regulating miR-30b-5p improved joint pain and loss of articular cartilage in the rats with restrained inflammation and NLRP3 inflammasome activation. Mechanistically, miR-30b-5p targeted the 3'-non-translated region (3'UTR) of SIRT1, and miR-30b-5p was inducible with NF-κB phosphorylation enhancement. Overexpressing SIRT1 or inhibiting NF-κB relieved miR-30b-5p-induced apoptosis and NLRP3 inflammasome activation by promoting FoxO3a, while down-regulating SIRT1 or FoxO3a reversed miR-30b-5p-in-induced anti-inflammatory and apoptosis-suppressive effects. Collectively, NF-κB-induced miR-30b-5p modulates chondrocyte apoptosis and OA progression by regulating the SIRT1-FoxO3a-mediated NLRP3 inflammasome.

FOXO and related transcription factors binding elements in the regulation of neurodegenerative disorders

Neurodegenerative diseases, such as Alzheimer's disease, Parkinson's disease, Huntington's disease, amyotrophic lateral sclerosis, and others, are characterized by progressive loss of neuronal cells, which causes memory impairment and cognitive decline. Mounting evidence demonstrated the possible implications of diverse biological processes, namely oxidative stress, mitochondrial dysfunction, aberrant cell cycle re-entry, post-translational modifications, protein aggregation, impaired proteasome dysfunction, autophagy, and many others that cause neuronal cell death. The condition worsens as there is no effective treatment for such diseases due to their complex pathogenesis and mechanism. Mounting evidence demonstrated the role of regulatory transcription factors, such as NFκβ, FoxO, Myc, CREB, and others that regulate the biological processes and diminish the disease progression and pathogenesis. Studies demonstrated that forkhead box O (FoxO) transcription factors had been implicated in the regulation of aging and longevity. Further, the functions of FoxO proteins are regulated by different post-translational modifications (PTMs), namely acetylation, and ubiquitination. Various studies concluded that FoxO proteins exert both neuroprotective and neurotoxic properties depending on their regulation mechanism and activity in the brain. Thus, understanding the nature of FoxO expression and activity in the brain will help develop effective therapeutic strategies. Herein, firstly, we discuss the role of FoxO protein in cell cycle regulation and cell proliferation, followed by the regulation of FoxO proteins through acetylation and ubiquitination. We also briefly explain the activity and expression pattern of FoxO proteins in the neuronal cells and explain the mechanism through which FoxO proteins are rescued from oxidative stress-induced neurotoxicity. Later on, we present a detailed view of the implication of FoxO proteins in neurodegenerative disease and FoxO proteins as an effective therapeutic target.

TRIM33 protects osteoblasts from oxidative stress-induced apoptosis in osteoporosis by inhibiting FOXO3a ubiquitylation and degradation

This study aimed to probe into the effect of TRIM33 on oxidative stress‐induced apoptosis of osteoblasts in osteoporosis and to probe into the underlying mechanism. The apoptosis of osteoblasts was induced by H₂O₂ treatment and tested by flow cytometry. A mouse osteoporosis model was conducted by ovariectomy (OVX). The function of TRIM33 was assessed by in vitro and in vivo experiments. The mechanism of TRIM33 was determined by immunoprecipitation, immunofluorescent staining and co‐transfection experiments. Here, we found that TRIM33 expression was lessened in the osteoblasts of patients with osteoporosis and was positively correlated with the bone mineral density of these patients. FOXO3a and TRIM33 were co‐localized in the osteoblasts nuclei. TRIM33 silence boosted FOXO3a degradation in normal osteoblasts, while TRIM33 overexpression restrained FOXO3a degradation in H₂O₂‐treated osteoblasts. The binding of TRIM33 to CBP and its overexpression restrained CBP‐mediated FOXO3a acetylation, thereby attenuating FOXO3a ubiquitylation. The H₂O₂‐induced apoptosis of osteoblasts was restrained by TRIM33 overexpression, while the FOXO3a knockdown reversed this trend. The in vivo experiments corroborated that TRIM33 overexpression attenuated the OVX‐driven impacts in mice. In general, our findings expounded that TRIM33 protected osteoblasts against oxidative stress‐induced apoptosis in osteoporosis and that the underlying mechanism was the restraint of FOXO3a ubiquitylation and degradation.

Bimodal regulation of the PRC2 complex by USP7 underlies tumorigenesis

Although overexpression of EZH2, a catalytic subunit of the polycomb repressive complex 2 (PRC2), is an eminent feature of various cancers, the regulation of its abundance and function remains insufficiently understood. We report here that the PRC2 complex is physically associated with ubiquitin-specific protease USP7 in cancer cells where USP7 acts to deubiquitinate and stabilize EZH2. Interestingly, we found that USP7-catalyzed H2BK120ub1 deubiquitination is a prerequisite for chromatin loading of PRC2 thus H3K27 trimethylation, and this process is not affected by H2AK119 ubiquitination catalyzed by PRC1. Genome-wide analysis of the transcriptional targets of the USP7/PRC2 complex identified a cohort of genes including FOXO1 that are involved in cell growth and proliferation. We demonstrated that the USP7/PRC2 complex drives cancer cell proliferation and tumorigenesis in vitro and in vivo. We showed that the expression of both USP7 and EZH2 elevates during tumor progression, corresponding to a diminished FOXO1 expression, and the level of the expression of USP7 and EZH2 strongly correlates with histological grades and prognosis of tumor patients. These results reveal a dual role for USP7 in the regulation of the abundance and function of EZH2, supporting the pursuit of USP7 as a therapeutic target for cancer intervention.

Molecular mechanisms of doxorubicin-induced cardiotoxicity: novel roles of sirtuin 1-mediated signaling pathways

Doxorubicin (DOX) is an anthracycline chemotherapy drug used in the treatment of various types of cancer. However, short-term and long-term cardiotoxicity limits the clinical application of DOX. Currently, dexrazoxane is the only approved treatment by the United States Food and Drug Administration to prevent DOX-induced cardiotoxicity. However, a recent study found that pre-treatment with dexrazoxane could not fully improve myocardial toxicity of DOX. Therefore, further targeted cardioprotective prophylaxis and treatment strategies are an urgent requirement for cancer patients receiving DOX treatment to reduce the occurrence of cardiotoxicity. Accumulating evidence manifested that Sirtuin 1 (SIRT1) could play a crucially protective role in heart diseases. Recently, numerous studies have concentrated on the role of SIRT1 in DOX-induced cardiotoxicity, which might be related to the activity and deacetylation of SIRT1 downstream targets. Therefore, the aim of this review was to summarize the recent advances related to the protective effects, mechanisms, and deficiencies in clinical application of SIRT1 in DOX-induced cardiotoxicity. Also, the pharmaceutical preparations that activate SIRT1 and affect DOX-induced cardiotoxicity have been listed in this review.

IL-38 restrains inflammatory response of collagen-induced arthritis in rats via SIRT1/HIF-1α signaling pathway

OBJECTIVE

To observe the restraining effect of IL-38 on inflammatory response in collagen-induced arthritis rats (CIA), and to explore the regulatory mechanism of SIRT1/HIF-1α signaling pathway.

METHODS

40 SD rats were randomly divided into Control group, CIA group, CLL group and CLH group, with 10 rats in each group; CIA rat model was established. The effects of IL-38 on arthritis index, inflammatory response, osteogenic factor and angiogenic factor were observed by methods including HE staining, ELISA, immunohistochemical and immunofluorescence. Human synoviocytes were cultured in vitro, and SIRT1 inhibitors were added to detect the expression for relating factors of SIRT1/HIF-1α signaling pathway by Western blot.

RESULTS

IL-38 could alleviate CIA joint damage and restrain inflammatory response, could up-regulate the expression of OPG in CIA rats and could down-regulate the expression of RANKL and RANK. IL-38 could restrain the expression of VEGF, VEGFR1, VEGFR2 and HIF. Moreover, we found that IL-38 could up-regulate the SIRT1 expression and down-regulate the HIF-1α, TLR4 and NF-KB p65 expression in CLL and CLH groups. From the treatment of synoviocytes to simulate the CIA model and the treatment of SIRT1 inhibitors, we demonstrated that the inhibitory effect of IL-38 on inflammatory factors and regulation of SIRT1/HIF-1α signaling pathway-related proteins were inhibited.

CONCLUSION

IL-38 can restrain the inflammatory response of CIA rats, can promote the expression of osteogenic factors, can inhibit neovascularization, and can alleviate joint damage in rats. The mechanism may be related to the regulation of SIRT1/HIF-1α signaling pathway.

LncRNA Sirt1-AS upregulates Sirt1 to attenuate aging related deep venous thrombosis

Aging is associated with the increased incidence of deep venous thrombosis (DVT), resulting in significant morbidity and mortality in the elderly, but the underlying mechanism is elusive. Silent information regulator 1 (Sirt1) is linked to the senescence, inflammation, oxidative stress and platelet adhesion of endothelial cells. Here we showed that DVT was associated with the senescence of endothelium and lower expression of Sirt1. Furthermore, Sirt1 could inhibit endothelial senescence and reduce the occurrence of DVT. Interestingly, we found antisense long non-coding RNA (lncRNA Sirt1-AS) upregulated Sirt1, decreased the expression of senescence and DVT associated biomarkers in human vascular endothelial cells (HUVECs). In addition, lncRNA Sirt1-AS overexpression alleviated DVT through upregulating Sirt1 and thereby inducing Foxo3a degradation. In conclusion, our findings demonstrate that lncRNA Sirt1-AS may be a potential new biomarker for DVT.

FGF21 promotes ischaemic angiogenesis and endothelial progenitor cells function under diabetic conditions in an AMPK/NAD+-dependent manner

Diabetic vascular complications are closely associated with long‐term vascular dysfunction and poor neovascularization. Endothelial progenitor cells (EPCs) play pivotal roles in maintaining vascular homeostasis and triggering angiogenesis, and EPC dysfunction contributes to defective angiogenesis and resultant diabetic vascular complications. Fibroblast growth factor 21 (FGF21) has received substantial attention as a potential therapeutic agent for diabetes via regulating glucose and lipid metabolism. However, the effects of FGF21 on diabetic vascular complications remain unclear. In the present study, the in vivo results showed that FGF21 efficiently improved blood perfusion and ischaemic angiogenesis in both type 1 and type 2 diabetic mice, and these effects were accompanied by enhanced EPC mobilization and infiltration into ischaemic muscle tissues and increases in plasma stromal cell–derived factor‐1 concentration. The in vitro results revealed that FGF21 directly prevented EPC damage induced by high glucose, and the mechanistic studies demonstrated that nicotinamide adenine dinucleotide (NAD⁺) was dramatically decreased in EPCs challenged with high glucose, whereas FGF21 treatment significantly increased NAD⁺ content in an AMPK‐dependent manner, resulting in improved angiogenic capability of EPCs. These results indicate that FGF21 promotes ischaemic angiogenesis and the angiogenic ability of EPCs under diabetic conditions by activating the AMPK/NAD⁺ pathway.

SIRT1, a promising regulator of bone homeostasis

Sirtuin 1 (SIRT1), a nicotinamide adenine dinucleotide-dependent deacetylase, epigenetically regulates various cell metabolisms, including inflammation, tumorigenesis, and bone metabolism. Many clinical studies have found the potential of SIRT1 in predicting and treating bone-related disorders, such as osteoporosis and osteonecrosis, suggesting that SIRT1 might be a regulator of bone homeostasis. In order to identify the mechanisms that underlie the pivotal role of SIRT1 in bone homeostasis, many studies revealed that SIRT1 could maintain the balance between bone formation and absorption via regulating the ratio of osteoblasts to osteoclasts. SIRT1 controls the differentiation of mesenchymal stem cells (MSCs) and bone marrow-derived macrophages, increasing osteogenesis and reducing osteoclastogenesis. Besides, SIRT1 can enhance bone-forming cells' viability, including MSCs and osteoblasts under adverse conditions by resisting senescence, suppressing apoptosis, and promoting autophagy in favor of osteogenesis. Furthermore, the effect on bone vasculature homeostasis enables SIRT1 to become a valuable strategy for ischemic osteonecrosis and senile osteoporosis. The review systemically discusses SIRT1 pathways and the critical role in bone homeostasis and assesses whether SIRT1 is a potential target for manipulation and therapy, to lay a solid foundation for further researches in the future.

Role of Forkhead box O3a transcription factor in autoimmune diseases

Forkhead box O3a (FOXO3a) transcription factor, the most important member of Forkhead box O family, is closely related to cell proliferation, apoptosis, autophagy, oxidative stress and aging. The downregulation of FOXO3a has been verified to be associated with the poor prognosis, severer malignancy and chemoresistance in several human cancers. The activity of FOXO3a mainly regulated by phosphorylation of protein kinase B. FOXO3a plays a vital role in promoting the apoptosis of immune cells. FOXO3a could also modulate the activation, differentiation and function of T cells, regulate the proliferation and function of B cells, and mediate dendritic cells tolerance and immunity. FOXO3a accommodates the immune response through targeting nuclear factor kappa-B and FOXP3, as well as regulating the expression of cytokines. Besides, FOXO3a participates in intercellular interactions. FOXO3a inhibits dendritic cells from producing interleukin-6, which inhibits B-cell lymphoma-2 (BCL-2) and BCL-XL expression, thereby sparing resting T cells from apoptosis and increasing the survival of antigen-stimulated T cells. Recently, plentiful evidences further illustrated the significance of FOXO3a in the pathogenesis of autoimmune diseases, including systemic lupus erythematosus, rheumatoid arthritis, inflammatory bowel disease, ankylosing spondylitis, myositis, multiple sclerosis, and systemic sclerosis. In this review, we focused on the biological function of FOXO3a and related signaling pathways regarding immune system, and summarized the potential role of FOXO3a in the pathogenesis, progress and therapeutic potential of autoimmune diseases.

Sirtuins play critical and diverse roles in acute kidney injury

Acute kidney injury (AKI) is an extremely common medical affliction affecting both adult and pediatric patients resulting from hypoxic, nephrotoxic, and septic insults affecting approximately 20% of all hospital patients and up to 50% of patients in the intensive care unit. There are currently no therapeutics for patients who suffer AKI. Much recent work has focused on designing and implementing therapeutics for AKI. This review focuses on a family of enzymes known as sirtuins that play critical roles in regulating many cellular and biological functions. There are 7 mammalian sirtuins (SIRT1-7) that play roles in regulating the acylation of a wide variety of pathways. Furthermore, all but one of the mammalian sirtuins have been shown to play critical roles in mediating AKI based on preclinical studies. These diverse enzymes show exciting potential for therapeutic manipulation. This review will focus on the specific roles of each of the investigated sirtuins and the potential for manipulation of the various sirtuins and their effector pathways in mediating kidney injury.

Advances in Studies on the Pharmacological Activities of Fucoxanthin

Fucoxanthin is a natural carotenoid derived mostly from many species of marine brown algae. It is characterized by small molecular weight, is chemically active, can be easily oxidized, and has diverse biological activities, thus protecting cell components from ROS. Fucoxanthin inhibits the proliferation of a variety of cancer cells, promotes weight loss, acts as an antioxidant and anti-inflammatory agent, interacts with the intestinal flora to protect intestinal health, prevents organ fibrosis, and exerts a multitude of other beneficial effects. Thus, fucoxanthin has a wide range of applications and broad prospects. This review focuses primarily on the latest progress in research on its pharmacological activity and underlying mechanisms.

Expression Regulation and Physiological Role of Transcription Factor FOXO3a During Ovarian Follicular Development

In mammals, developing ovarian follicles transform from primordial follicles to primary follicles, secondary follicles, and mature follicles, accompanied by changes in follicular secretory functions. FoxO3a is a member of the forkhead transcription factor family (FoxO), which plays an important role in the cell cycle, DNA damage repair, apoptosis, oxidative stress, and energy metabolism. Recent studies have shown that FOXO3a is involved in the physiological regulation of follicular development and pathological progression of related ovarian diseases, which will provide useful concepts and strategies for retarding ovarian aging, prolonging the ovarian life span, and treating ovarian diseases. Therefore, the regulation of FOXO3a expression, as well as the physiological contribution during ovarian follicular development are detailed in this paper, presenting an important reference for the further study of ovarian biology.

SIRT1-modified human umbilical cord mesenchymal stem cells ameliorate experimental peritoneal fibrosis by inhibiting the TGF-β/Smad3 pathway

Introduction

Peritoneal fibrosis is a serious complication of long-term peritoneal dialysis (PD). Combination therapies are emerging as a promising treatment for tissue damage. Here, we investigated the therapeutic potential of SIRT1-modified human umbilical cord mesenchymal stem cells (hUCMSCs) for peritoneal fibrosis.

Methods

SIRT1 was overexpressed in hUCMSCs to establish SIRT1-modified hUCMSCs. Co-culture and transplantation experiments were performed in TGF-β-stimulated Met-5A cells and peritoneal damage rodent model to assess the therapeutic potential of SIRT1-modified hUCMSCs for peritoneal fibrosis through qPCR, Western blot, and peritoneal function analyses.

Results

SIRT1-modified hUCMSC administration had more potent anti-fibrosis ability than hUCMSCs, which significantly inhibited the expression of fibrotic genes and suppressed EMT process, increased ultrafiltration volume, and restored homeostasis of bioincompatible factors in dialysis solution. Mechanistically, SIRT1-modified hUCMSCs attenuated peritoneal fibrosis through reducing peritoneal inflammation and inhibiting the TGF-β/Smad3 pathway in peritoneal omentum tissues.

Conclusion

SIRT1-modified hUCMSCs might work as a promising therapeutic strategy for the treatment of peritoneal dialysis-induced peritoneal damage and fibrosis.

Ginsenoside Rd Ameliorates Auditory Cortex Injury Associated With Military Aviation Noise-Induced Hearing Loss by Activating SIRT1/PGC-1α Signaling Pathway

Free radicals and oxidative stress play an important role in the pathogenesis of noise-induced hearing loss (NIHL). Some ginseng monomers showed certain therapeutic effects in NIHL by scavenging free radicals. Therefore, we hypothesized that ginsenoside Rd (GSRd) may exert neuroprotective effects after noise-induced auditory system damage through a mechanism involving the SIRT1/PGC-1α signaling pathway. Forty-eight guinea pigs were randomly divided into four equal groups (normal control group, noise group, experimental group that received GSRd dissolved in glycerin through an intraperitoneal injection at a dose of 30 mg/kg body weight from 5 days before noise exposure until the end of the noise exposure period, and experimental control group). Hearing levels were examined by auditory brainstem response (ABR) and distortion product otoacoustic emission (DPOAE). Hematoxylin-eosin and Nissl staining were used to examine neuron morphology. RT-qPCR and western blotting analysis were used to examine SIRT1/PGC-1α signaling and apoptosis-related genes, including Bax and Bcl-2, in the auditory cortex. Bax and Bcl-2 expression was assessed via immunohistochemistry analysis. Superoxide dismutase (SOD), malondialdehyde (MDA), and glutathione peroxidase (GSH-Px) levels were determined using a commercial testing kit. Noise exposure was found to up-regulate ABR threshold and down-regulate DPOAE amplitudes, with prominent morphologic changes and apoptosis of the auditory cortex neurons (p < 0.01). GSRd treatment restored hearing loss and remarkably alleviated morphological changes or apoptosis (p < 0.01), concomitantly increasing Bcl-2 expression and decreasing Bax expression (p < 0.05). Moreover, GSRd increased SOD and GSH-Px levels and decreased MDA levels, which alleviated oxidative stress damage and activated SIRT1/PGC-1α signaling pathway. Taken together, our findings suggest that GSRd ameliorates auditory cortex injury associated with military aviation NIHL by activating the SIRT1/PGC-1α signaling pathway, which can be an attractive pharmacological target for the development of novel drugs for NIHL treatment.

Sex-based differences in myocardial infarction-induced kidney damage following cigarette smoking exposure: more renal protection in premenopausal female mice

The impact of cigarette smoking (CS) on kidney homeostasis in the presence of myocardial infarction (MI) in both males and females remains poorly elucidated. C57BL6/J mice were exposed to 2 weeks of CS prior to MI induction followed by 1 week of CS exposure in order to investigate the impact of CS on kidney damage in the presence of MI. Cardiac hemodynamic analysis revealed a significant decrease in ejection fraction (EF) in CS-exposed MI male mice when compared with the relative female subjects, whereas cardiac output (CO) comparably decreased in CS-exposed MI mice of both sexes. Kidney structural alterations, including glomerular retraction, proximal convoluted tubule (PCT) cross-sectional area, and total renal fibrosis were more pronounced in CS-exposed MI male mice when compared with the relative female group. Although renal reactive oxygen species (ROS) generation and glomerular DNA fragmentation significantly increased to the same extent in CS-exposed MI mice of both sexes, alpha-smooth muscle actin (α-SMA) and connective tissue growth factor (CTGF) significantly increased in CS-exposed MI male mice, only. Metabolically, nicotinamide phosphoribosyltransferase (NAMPT) and nicotinamide riboside-1 (NMRK-1) substantially increased in CS-exposed MI female mice only, whereas sirtuin (SIRT)-1 and SIRT-3 substantially decreased in CS-exposed MI male mice compared with their relative female group. Additionally, renal NAD levels significantly decreased only in CS-exposed MI male mice. In conclusion, MI female mice exhibited pronounced renal protection following CS when compared with the relative male groups.

Cyclosporine A induces testicular injury via mitochondrial apoptotic pathway by regulation of mir-34a and sirt-1 in male rats: The rescue effect of curcumin

Testicular damage contributes to cyclosporine A (CsA) induced male infertility. However, the exact underlying molecular mediators involved in CsA-induced testis disorder remains unclear. The present study aimed to characterize the role of mir-34a/sirt-1 in CsA induced testicular injury alone or in combination with curcumin. A total of twenty-eight male Wistar rats were subdivided into four groups: control (Con), sham, cyclosporine A (CsA), cyclosporineA + curcumin (CsA + cur). The animals received cyclosporine A (30 mg/kg) and curcumin (40 mg/kg) for 28 days by oral gavage. At the end of the experiment, CsA administration significantly resulted in a decrease in testis weight and testis coefficient. The molecular analysis demonstrated that CsA exposure increased 8-OHdg and Nox4 protein contents in the testis tissue. TUNEL staining indicated that CsA caused the number of apoptotic cells to increase in the testes of male rats. In addition, exposure to CsA resulted in an increased expression of Bax, and a decreased expresion in that of Bcl-2, with a concomitant up-regulation of the Bax/Bcl-2, c-Caspase-3/p-Caspase-3 ratio and cytochrome c level. Meanwhile, exposure to CsA increased the expression of mir-34a and decreased sirt-1 protein level in the testis tissue samples compared to the control group. Taken together, our findings suggested that CsA can cause damage to testicular germ cells via oxidative stress and mitochondrial apoptotic pathway, and probably mir-34a/sirt-1 play a crucial role in this process. It also demonstrates that these negative effects of CsA can be reduced by using curcumin as an antioxidant and anti-inflammatory agent.

Down-regulation of miR-133a-3p protects lung tissue against sepsis-induced acute respiratory distress syndrome by up-regulating SIRT1

Introduction

MicroRNA-133a-3p (miR-133a-3p) is a potential gene regulator having an important role in the process of inflammation and lung injury. The present work studied the role of miR-133a-3p in sepsis-mediated acute respiratory distress syndrome (ARDS) and the mechanism involved.

Material and methods

C57BL/6 mice were selected for the study. Protein expression of Bcl-2, cleaved caspase-3 and Bax was assessed by western blot analysis. Expression of mRNA was assessed by RT-PCR. Effects of inflammation were studied by myeloperoxidase (MPO) activity. Quantification of albumin was done by measuring the albumin conjugated with Evan's blue. The alveolar macrophages were separated from the lungs of mice by the bronchoalveolar lavage procedure and were submitted to sepsis challenge in vitro; the macrophages were treated with lipopolysaccharide (LPS).

Results

Treatment of LPS resulted in upregulation of miR-133a-3p in alveolar macrophages. Suppression of miR-133a-3p halted the over-expression of inflammatory cytokines in macrophages and caused remission of histopathologic changes. The ARDS lungs showed a decrease in levels of proinflammatory cytokines and an increase in levels of apoptotic protein, establishing the protective role for miR-133a-3p. The results suggested sirtuin 1 (SIRT1) as a potential target of miR-133a-3p in the macrophages, also showing that expression of SIRT1 was inversely associated with expression of miR-133a-3p. The protective effect of miR-133a-3p down-regulation in LPS-mediated alveolar macrophages and sepsis-induced ARDS could be corrected by a SIRT1 inhibitor.

Conclusions

Down-regulation of miR-133a-3p may exert a protective effect on lung tissue against sepsis-mediated ARDS by up-regulating the levels of SIRT1 via suppressing the inflammatory response and inhibiting the cellular apoptosis in lung tissues.

High expression of FOXO3 is associated with poor prognosis in patients with hepatocellular carcinoma

The role of forkhead box O3 (FOXO3) as a tumor suppressor gene and its association with the human lifespan is well documented. However, several studies have indicated that high expression of FOXO3 is also significantly associated with tumorigenesis. The aim of the present study was to determine the clinical significance of FOXO3 in the development and prognosis of hepatocellular carcinoma (HCC). mRNA expression data of FOXO3 from The Cancer Genome Atlas database was analyzed through the UALCAN online tool to compare the expression of FOXO3 between HCC and normal liver tissues. Subsequently, the expression of FOXO3 at the protein level was investigated via immunohistochemical staining of 314 HCC and 150 non-cancerous liver tissue samples. The association between protein expression and clinicopathological parameters was analyzed using the χ² test, and the effect of FOXO3 expression on survival was assessed via Kaplan-Meier analysis. The expression of FOXO3 mRNA was significantly higher in HCC in comparison with healthy tissues. High FOXO3 protein expression was revealed in 43/150 non-cancerous liver tissues, and in 238/314 HCC samples. A significant association was demonstrated between FOXO3 expression and metastasis, Tumor-Node-Metastasis stage, Edmondson grade, α-fetoprotein level and overall survival. In conclusion, the high expression of FOXO3 predicts a poor prognosis in patients with HCC, indicating this protein as a potential therapeutic target in HCC.

Sirtuin-1 and Its Relevance in Vascular Calcification

Vascular calcification (VC) is highly associated with cardiovascular disease and all-cause mortality in patients with chronic kidney disease. Dysregulation of endothelial cells and vascular smooth muscle cells (VSMCs) is related to VC. Sirtuin-1 (Sirt1) deacetylase encompasses a broad range of transcription factors that are linked to an extended lifespan. Sirt1 enhances endothelial NO synthase and upregulates FoxOs to activate its antioxidant properties and delay cell senescence. Sirt1 reverses osteogenic phenotypic transdifferentiation by influencing RUNX2 expression in VSMCs. Low Sirt1 hardly prevents acetylation by p300 and phosphorylation of β-catenin that, following the facilitation of β-catenin translocation, drives osteogenic phenotypic transdifferentiation. Hyperphosphatemia induces VC by osteogenic conversion, apoptosis, and senescence of VSMCs through the Pit-1 cotransporter, which can be retarded by the sirt1 activator resveratrol. Proinflammatory adipocytokines released from dysfunctional perivascular adipose tissue (PVAT) mediate medial calcification and arterial stiffness. Sirt1 ameliorates release of PVAT adipokines and increases adiponectin secretion, which interact with FoxO 1 against oxidative stress and inflammatory arterial insult. Conclusively, Sirt1 decelerates VC by means of influencing endothelial NO bioavailability, senescence of ECs and VSMCs, osteogenic phenotypic transdifferentiation, apoptosis of VSMCs, ECM deposition, and the inflammatory response of PVAT. Factors that aggravate VC include vitamin D deficiency-related macrophage recruitment and further inflammation responses. Supplementation with vitamin D to adequate levels is beneficial in improving PVAT macrophage infiltration and local inflammation, which further prevents VC.

Swimming training by affecting the pancreatic Sirtuin1 (SIRT1) and oxidative stress, improves insulin sensitivity in diabetic male rats

Background

Sirtuin1 is a regulator of oxidative stress involved in the management of diabetes complications. Due to the beneficial effects of swimming training in diabetes, this study aimed to investigate the effects of swimming training on pancreatic Sirtuin1, oxidative stress and metabolic parameters in type 2 diabetic male rats.

Materials and methods

Twenty-eight male Wistar rats (200–250 g) were randomly divided into four groups: control, diabetic, swim trained and swim trained diabetic rats (n = 7). Diabetes was induced by a high-fat diet and streptozotocin injection [35/kg intraperitoneally]. After 72 hours, animals with blood glucose levels ≥300 mg/dL were considered diabetic. Seven days after the induction of diabetes, animals in the exercise groups were subjected to swimming training (60 min/daily, 5 days/week) for 12 weeks. At the end of the intervention, the animals were anesthetized, and tissue/blood samples were prepared for measurements of metabolic parameters, albumin, the Sitruin1 gene and its protein expression levels, oxidative stress and histological study.

Results

This study indicated that the diabetic rats had a significant decrease (p < 0.01, p < 0.05) in pancreatic Sitruin1 gene and its protein expression levels, antioxidant enzymes, serum albumin, and the quantitative insulin sensitivity check index, but a significant increase (p < 0.01) in malondialdehyde level. Swimming training resulted in a considerable improvement (p < 0.01, p < 0.05) in pancreatic Sitruin1 gene and its protein expression levels, antioxidant enzymes, serum levels of albumin and metabolic parameters. In addition, histological findings indicated the beta-cells conservation.

Conclusions

This study suggested that pancreatic Sitruin1 may be a promising therapeutic target for diabetic complications.

Fucoxanthin Alleviates Oxidative Stress through Akt/Sirt1/FoxO3α Signaling to Inhibit HG-Induced Renal Fibrosis in GMCs

As one of the main marine carotenoids, fucoxanthin has strong antioxidant activity. FoxO3α, a member of the forkhead box O family of transcription factors, plays an important role in DN by regulating oxidative stress. The activity of FoxO3α is related to its phosphorylation and acetylation status, regulated by Akt and Sirt1, a lysine deacetylase. Our study aimed to investigate whether fucoxanthin could alleviate oxidative stress and fibrosis via FoxO3α in DN and whether Akt and Sirt1 were involved. We found that in GMCs cultured in HG, fucoxanthin treatment significantly reduced the expression of FN and collagen IV, as well as reactive oxygen species generation, suggesting that fucoxanthin is beneficial to alleviate both fibrosis and oxidative stress in DN. In addition, we found that fucoxanthin decreased the phosphorylation and acetylation level of FoxO3α, reversed the protein level of FoxO3α inhibited by HG, and then promoted the nuclear transport of FoxO3α. Besides, fucoxanthin promoted the expression of manganese superoxide dismutase, a downstream target of FoxO3α. Furthermore, we found that fucoxanthin reversed the activation of Akt and inhibition of Sirt1. However, the enhancement of fucoxanthin in FoxO3α expression and nuclear transport was significantly decreased by pretreatment with Akt activator SC79 or Sirt1 inhibitor EX527. In summary, our study explored fucoxanthin alleviated oxidative stress and fibrosis induced by HG through Akt/Sirt1/FoxO3α signaling in GMCs, suggesting fucoxanthin is a potential therapeutic strategy for DN.

MeCP2 inhibits cell functionality through FoxO3a and autophagy in endothelial progenitor cells

Objectives: Autophagy is an evolutionarily conserved intracellular degradation mechanism in which cell constituents are phagocytosed to maintain cellular homeostasis. Forkhead box O 3a (FoxO3a) promotes autophagy to protect cells from environmental stress. Methylated CpG binding protein 2 (MeCP2) is a nuclear protein that binds DNA and represses transcription. However, the mechanism and interplay between FoxO3a and MeCP2 underlying endothelial progenitor cell (EPC) function are not fully understood.

Results: In EPCs, MeCP2 overexpression attenuated autophagy and cell functionality, which were reversed by the autophagy activator rapamycin or co-transfection with FoxO3a. FoxO3a promoted cell function, which was reversed by the autophagy inhibitor chloroquine. Following MeCP2 overexpression, MeCP2 was found enriched on the FoxO3a promoter, resulting in promoter hypermethylation and enhanced H3K9 histone modification in nucleosomes of the FoxO3a promoter.

Conclusions: MeCP2 attenuated cell functionality via DNA hypermethylation and histone modification of the FoxO3a promoter to inhibit FoxO3a transcription and autophagy.

Materials and Methods: EPCs were isolated from human umbilical cord blood and treated with adenoviral vectors containing interference sequences. The effects and mechanism of MeCP2 and FoxO3a were analyzed by utilizing western blotting, cell counting kit-8, transwell plates, Matrigel, matrix adhesion, transmission electron microscopy, and chromatin immunoprecipitation.