Human cytomegalovirus modulates mTORC1 to redirect mRNA translation within quiescently infected monocytes.

Human cytomegalovirus (HCMV) utilizes peripheral blood monocytes as a means to systemically disseminate throughout the host. Following viral entry, HCMV stimulates non-canonical Akt signaling leading to the activation of mTORC1 and the subsequent translation of select antiapoptotic proteins within infected monocytes. However, the full extent to which the HCMV-initiated Akt/mTORC1 signaling axis reshapes the monocyte translatome is unclear. We found HCMV entry alone was able to stimulate widescale changes to mRNA translation levels and that inhibition of mTOR, a component of mTORC1, dramatically attenuated HCMV-induced protein synthesis. Although monocytes treated with normal myeloid growth factors also exhibited increased levels of translation, mTOR inhibition had no effect, suggesting HCMV activation of mTOR stimulates the acquisition of a unique translatome within infected monocytes. Indeed, polyribosomal profiling of HCMV-infected monocytes identified distinct prosurvival transcripts that were preferentially loaded with ribosomes when compared to growth factor-treated cells. Sirtuin 1 (SIRT1), a deacetylase that exerts prosurvival effects through regulation of the PI3K/Akt pathway, was found to be highly enriched following HCMV infection in an mTOR-dependent manner. Importantly, SIRT1 inhibition led to the death of HCMV-infected monocytes while having minimal effect on uninfected cells. SIRT1 also supported a positive feedback loop to sustain Akt/mTORC1 signaling following viral entry. Taken together, HCMV profoundly reshapes mRNA translation in an mTOR-dependent manner to enhance the synthesis of select factors necessary for the survival of infected monocytes.IMPORTANCEHuman cytomegalovirus (HCMV) infection is a significant cause of morbidity and mortality among the immunonaïve and immunocompromised. Peripheral blood monocytes are a major cell type responsible for disseminating the virus from the initial site of infection. In order for monocytes to mediate viral spread within the host, HCMV must subvert the naturally short lifespan of these cells. In this study, we performed polysomal profiling analysis, which demonstrated HCMV to globally redirect mRNA translation toward the synthesis of cellular prosurvival factors within infected monocytes. Specifically, HCMV entry into monocytes induced the translation of cellular SIRT1 to generate an antiapoptotic state. Defining the precise mechanisms through which HCMV stimulates survival will provide insight into novel anti-HCMV drugs able to target infected monocytes.

Expression and significance of silent information regulator two homolog 1 in the placenta and plasma of patients with pre-eclampsia-a meta-analysis.

OBJECTIVE: This study aimed to collect, organize, and conduct a meta-analysis of the literature on the expression of silent information regulator two homolog 1 (SIRT1) in the placental tissue and plasma of patients with pre-eclampsia. METHODS: The enrolled patients were divided into two groups: the pre-eclampsia group and the healthy group. This study summarized and analyzed the demographic characteristics of the two groups, including pregnancy age, gestational weeks, parity, gravidity, blood pressure, Body Mass Index, newborn weight, placental weight, and SIRT1 expression in placental tissue and maternal plasma. RESULTS: Eleven studies were included in this research, with 586 cases in the pre-eclampsia group and 479 cases in the control group. Three research studies are reporting immunohistochemistry tests, among which the pre-eclampsia group had a positivity rate of 30.24% (62/205), while the control group had 58.02% (76/131); the two groups have a significant difference (p < 0.05). Two research studies reported the results of ELISA tests, with 107 cases in the pre-eclampsia group and 125 cases in the control group. A comparison of the SIRT1 test results showed a statistically significant difference between the two groups (p < 0.05). Pre-eclampsia group patients had lower gestational weeks, newborn birth weight, and placental weight compared to the healthy control group (all p < 0.05). However, systolic and diastolic blood pressures were higher in the pre-eclampsia group than in the control group (p < 0.05). CONCLUSION: SIRT1 expression is downregulated in pre-eclampsia patients' plasma and placental tissue. Further research is needed to validate this conclusion.

The anti-tumour effect of induced pluripotent stem cells against submandibular gland carcinoma in rats is achieved via modulation of the apoptotic response and the expression of Sirt-1, TGF-ß, and MALAT-1 in cancer cells.

The era of induced pluripotent stem cells (iPSCs) was used as novel biotechnology to replace embryonic stem cells bypassing the ethical concerns and problems of stem cell transplant rejection. The anti-tumour potential of iPSCs against many tumours including salivary cancer was proven in previous studies. The current study aimed to investigate the contribution of the Bax, Sirt-1, TGF-ß, and MALAT genes and/or their protein expression to the pathogenesis of submandibular carcinogenesis before and after iPSCs treatment. Thirty Wistar albino rats were equally assigned into three groups: group I (control), group II (Squamous cell carcinoma (SCC)): submandibular glands were injected SCC cells, and group III (SCC/iPSCs): SCC rats were treated by 5 × 106 iPSCs. Submandibular gland sections were subjected to histological and immunohistochemical analyses to detect mucopolysaccharides, Bax, and TGF-ß expression as well as PCR quantification for TGF-ß, Sirt-1, and lncRNA MALAT-1 gene expressions. Western blotting was also used to detect Sirt-1 and TGF-ß protein expressions. SCC group revealed infiltration by sheets of malignant squamous cells with or without keratin pearls and inflammatory cells, in addition to upregulation of TGF-ß, Sirt-1, MALAT-1, and Bax, whereas SCC/iPSCs group showed an improved submandibular histoarchitecture with the maintenance of the secretory function. Bax and TGF-ß immunoexpression were significantly reduced. The upregulated TGF-ß, Sirt-1, and MALAT-1 genes were significantly decreased. iPSCs protected against the experimentally induced submandibular gland carcinoma that might be achieved via their regenerative potential and their regulatory modulation of Sirt-1, TGF-ß, and MALAT-1 gene/protein expressions and of the apoptotic response in cancer cells.

Resveratrol ameliorates myocardial fibrosis by regulating Sirt1/Smad3 deacetylation pathway in rat model with dilated cardiomyopathy.

BACKGROUND: The aim of this study was to investigate the effects of Resveratrol (RSV) in rats with dilated cardiomyopathy (DCM). METHODS: Porcine cardiac myosin was used to set up rat model with DCM. RSV (10 mg/kg in RSV-L group and 50 mg/kg in RSV-H group) or vehicle was administered to rats with DCM once daily from the 28th day till the 90th day after the first immunization. Cardiac function of rats was evaluated by echocardiographic analysis. The deposition of fibrous tissues in the hearts was evaluated by Masson and picrosirius red staining. The mRNA levels of collagen type I (Col I), collagen type III (Col III) and silence information regulator 1 (Sirt1) were measured by quantitative real-time polymerase chain reaction (qRT-PCR). The interaction of Sirt1 with Smad3 was revealed by coimmunoprecipitation. RESULTS: The heart weight, heart weight/body weight ratio, left ventricular end diastolic diameter (LVEDD) and left ventricular end systolic diameter (LVESD) were significantly increased in rats with DCM, and attenuated by RSV. RSV also positively decreased fibrosis, and the expression of Col I and Col III in the myocardium. The Sirt1 mRNA was significantly decreased in myosin-immunized hearts and was positively increased by RSV. The Sirt1 combined with Smad3 directly. Acetylation of Smad3 (Ac-Smad3) was significantly increased in DCM and was markedly decreased by RSV. CONCLUSION: RSV effectively ameliorated myocardial fibrosis and improved cardiac function by regulating Sirt1/Smad3 deacetylation pathway in rat model with DCM.

Resveratrol inhibits the progression of premature senescence partially by regulating v-rel avian reticuloendotheliosis viral oncogene homolog A (RELA) and sirtuin 1 (SIRT1).

OBJECTIVE: To explore the effect of resveratrol in premature senescence and reveal its anti-premature senescence mechanisms through network pharmacology. METHODS: In this study, the H2O2-induced bone marrow mesenchymal stem cells (BMMSCs) premature senescence model is applied. Cell counting kit-8 assay, ß-galactosidase staining and flow cytometry are conducted to detect the proliferation, senescence and apoptosis of BMMSCs. Bioinformatics analyses are used to screen and validate molecular targets of resveratrol acting on premature senescence. Dual-luciferase reporter assay is conducted to verify the interaction between v-rel avian reticuloendotheliosis viral oncogene homolog A (RELA) and sirtuin 1 (SIRT1). RT-qPCR and western blot are adopted to detect mRNA and protein levels of RELA, SIRT1, senescence-related genes and apoptosis-related genes. RESULTS: First, we proved that resveratrol alleviated the H2O2-induced senescence of BMMSCs. Then, bioinformatics analysis revealed that RELA was the downstream target of resveratrol and SIRT1 was the downstream target of RELA, respectively, involved in premature aging. RELA/SIRT1 may be the potential target of resveratrol for premature senescence. Notably, rescue experiments indicated that resveratrol inhibited premature senescence partially through targeting regulation RELA/SIRT1. CONCLUSION: In our study, we confirm the functional role of the resveratrol-RELA- SIRT1 axis in the progression of premature senescence, which provides a latent target for premature senescence treatment.

Overexpressing STAMP2 attenuates diabetic renal injuries via upregulating autophagy in diabetic rats.

Diabetic nephropathy (DN) is one of the most serious and major renal complications of diabetes. Previously, Six-transmembrane Protein of Prostate 2 (STAMP2) was reported to contribute to nutritional stress. The purpose of this study is to investigate whether overexpression of STAMP2 attenuates diabetic renal injuries in DN rats. We induced the DN rat model by high-fat diet and low-dose streptozotocin and evaluated the metabolite and urine albumin/creatinine. Recombinant adeno-associated virus vectors were injected for overexpression of STAMP2. Pathophysiologic and ultrastructure features of DN by histochemical stain and transmission electron microscope, autophagy-related proteins and signaling pathway by western blotting were assessed. We found the expression of STAMP2 was decreased and autophagy was blunted in DN rat kidneys. Overexpressing STAMP2 significantly ameliorated metabolic disturbance, insulin resistance, and specifically restoring diabetic renal injury. Furthermore, overexpressing STAMP2 improved the autophagy deficiency in DN rats, as revealed by changes in the expressions of Beclin1, p62, and LC3. Furthermore, STAMP2 overexpressing promoted autophagy by inhibiting the mTOR and activating the AMPK/SIRT1 signaling pathway. Our results suggested that STAMP2 overexpression attenuated renal injuries via upregulating autophagy in DN rats. STAMP2 overexpressing promoted autophagy may been involved with inhibition of the mTOR/ULK1 and activation of the AMPK/SIRT1 signaling pathway.

Activation of GPR39 with TC-G 1008 attenuates neuroinflammation via SIRT1/PGC-1α/Nrf2 pathway post-neonatal hypoxic-ischemic injury in rats.

BACKGROUND: Hypoxic-ischemic encephalopathy (HIE) is a severe anoxic brain injury that leads to premature mortality or long-term disabilities in infants. Neuroinflammation is a vital contributor to the pathogenic cascade post-HIE and a mediator to secondary neuronal death. As a plasma membrane G-protein-coupled receptor, GPR39, exhibits anti-inflammatory activity in several diseases. This study aimed to explore the neuroprotective function of GPR39 through inhibition of inflammation post-hypoxic-ischemic (HI) injury and to elaborate the contribution of sirtuin 1(SIRT1)/peroxisome proliferator-activated receptor-γ coactivator 1α (PGC-1α)/nuclear factor, erythroid 2 like 2(Nrf2) in G-protein-coupled receptor 39 (GPR39)-mediated protection. METHODS: A total of 206 10-day-old Sprague Dawley rat pups were subjected to HIE or sham surgery. TC-G 1008 was administered intranasally at 1 h, 25 h, 49 h, and 73 h post-HIE induction. SIRT1 inhibitor EX527, GPR39 CRISPR, and PGC-1α CRISPR were administered to elucidate the underlying mechanisms. Brain infarct area, short-term and long-term neurobehavioral tests, Nissl staining, western blot, and immunofluorescence staining were performed post-HIE. RESULTS: The expression of GPR39 and pathway-related proteins, SIRT1, PGC-1α and Nrf2 were increased in a time-dependent manner, peaking at 24 h or 48-h post-HIE. Intranasal administration of TC-G 1008 reduced the percent infarcted area and improved short-term and long-term neurological deficits. Moreover, TC-G 1008 treatment significantly increased the expression of SIRT1, PGC-1α and Nrf2, but downregulated the expressions of IL-6, IL-1ß, and TNF-α. GPR39 CRISPR EX527 and PGC-1α CRISPR abolished GPR39's neuroprotective effects post-HIE. CONCLUSIONS: TC-G 1008 attenuated neuroinflammation in part via the SIRT1/PGC-1α/Nrf2 pathway in a neonatal rat model of HIE. TC-G 1008 may be a novel therapeutic target for treatment post-neonatal HIE injury.

6,4'-dihydroxy-7-methoxyflavanone protects against H2O2-induced cellular senescence by inducing SIRT1 and inhibiting phosphatidylinositol 3-kinase/Akt pathway activation.

6, 4'-Dihydroxy-7-methoxyflavanone (DMF) has been shown to possess anti-inflammatory, anti-oxidative, and neuroprotective activities. However, its effect on oxidative stress-induced aging remains undemonstrated. This study aimed at investigating the anti-senescence effect of DMF on hydrogen peroxide (H2O2)-induced premature senescence, and associated molecular mechanisms in human dermal fibroblasts (HDFs). The cells were DMF pretreated with small interfering RNA (siRNAs) of control or sirtuin 1 (SIRT1) before H2O2 exposure, and western blot analysis, senescence-associated ß-galactosidase (SA-ß-gal) activity, cell counting, gene silencing, and SIRT1 activity assay were performed. Pretreatment with DMF inhibited H2O2-induced senescence phenotypes, which showed decreased SA-ß-gal activity and increased cell growth in comparison with H2O2-treated HDFs. Meanwhile, the decreases in ac-p53, p21Cip1/WAF1, and p16Ink4a and the increases in pRb and cyclin D1 were observed. DMF was also found to induce SIRT1 expression and activity level concentration- and time-dependently. Moreover, SIRT1 inhibition abrogated DMF senescence prevention. Additionally, Akt and ERK were activated with different kinetics after H2O2 exposure, and Akt activity inhibition attenuated SA-ß-gal activity augmentation. We also found that DMF inhibited H2O2-induced Akt phosphorylation. This study indicates that DMF effectively protects against oxidative stress-induced premature senescence through SIRT1 expression up-regulation and Akt pathway inhibition in HDFs. These results suggest that DMF can be a potential therapeutic molecule for age-related diseases, or a protective agent against the aging process.

Juzentaihoto Suppresses Muscle Atrophy and Decreased Motor Function in SAMP8 Mice.

Sarcopenia is a disease whose symptoms include decreased muscle mass and weakened muscle strength with age. In sarcopenia, decreased production of insulin-like growth factor-1 (IGF-1) increases ubiquitin ligases, such as Atrogin1 and Muscle RING-Finger Protein-1 (MuRF1), by activating forkhead box O (FOXO), and inflammatory cytokines and oxidative stress increase the expression of ubiquitin ligases by activating the transcription factor nuclear factor-kappa B (NF-κB). In addition, increased levels of ubiquitin ligases cause skeletal muscle atrophy. Conversely, sirtuin 1 (Sirt1) is known to regulate the expression of ubiquitin ligases by suppressing the activities of NF-κB and FOXO. In this study, we evaluated the effect that juzentaihoto hot water extract (JTT) has on skeletal muscle atrophy and motor function by administering it to senescence-accelerated mouse prone-8 (SAMP8). The group treated with JTT displayed larger gastrocnemius muscle (GA) and extensor digitorum longus (EDL) weights, larger GA muscle fiber cross-sectional areas, and motor function decline during rota-rod tests. JTT also increased IGF-1 serum levels, as well as mRNA Sirt1 levels in GA. Serum levels of tumor necrosis factor-α, interleukin-6, and mRNA levels of Atrogin1 and MuRF1 in GA were reduced by JTT. The muscle fiber cross-sectional area of GA was correlated with the mRNA levels of Sirt1 in GA. The results of this study suggested that JTT administration suppresses skeletal muscle atrophy and motor function decline in SAMP8 mice. This effect may be associated with the increased expression levels of Sirt1 and IGF-1 by JTT.

Gastrodia elata Blume Polysaccharides Attenuate Vincristine-Evoked Neuropathic Pain through the Inhibition of Neuroinflammation.

Vincristine (Vin) is a well-known antitumor agent that frequently evokes neuropathic pain and decreases the quality of life of patients. Polysaccharides (GBP) extracted from Gastrodia elata Blume have been demonstrated to possess anti-inflammatory and neuroprotective effects in vivo; however, the effects of GBP on Vin-induced neuropathic pain remain unknown. The present study is aimed at exploring the alleviative potential of GBP against chemotherapy-evoked peripheral neuropathy to better understand and extend its pharmacological application. Vin was administered intraperitoneally to evoke neuropathic pain. GBP was orally administered for 21 days. The mechanical allodynia and thermal hyperalgesia were assessed using the Von Frey test and hot-plate test. Histopathological changes were assessed by hematoxylin and eosin staining. ELISA kits were used to measure the levels of inflammatory cytokines in the sciatic nerve, spinal cord, and dorsal root ganglion (DRG). qRT-PCR was employed to examine the expression of inflammatory cytokines and Sirtuin1 (SIRT1) in the sciatic nerve, spinal cord, and DRG. Our findings revealed that GBP treatment enhanced the paw withdrawal latency and paw withdrawal threshold and restored Vin-induced sciatic nerve damage in rats. GBP also attenuated the Vin-induced increase of proinflammatory cytokine levels, including IL-6, IL-8, TNF-α, IL-1ß, and NF-κB. On the molecular level, treatment with GBP downregulated the mRNA levels of IL-6, IL-8, TNF-α, and IL-1ß in the sciatic nerve, spinal cord, and DRG. Meanwhile, GBP increased SIRT1 activity and mRNA expression levels. Our data indicated that GBP exerted a potential protective effect against chemotherapy-induced neuropathic pain which might be mediated via the inhibition of neuroinflammation.

Hyperoside Attenuate Inflammation in HT22 Cells via Upregulating SIRT1 to Activities Wnt/ß-Catenin and Sonic Hedgehog Pathways.

Neuroinflammation plays important roles in the pathogenesis and progression of altered neurodevelopment, sensorineural hearing loss, and certain neurodegenerative diseases. Hyperoside (quercetin-3-O-ß-D-galactoside) is an active compound isolated from Hypericum plants. In this study, we investigate the protective effect of hyperoside on neuroinflammation and its possible molecular mechanism. Lipopolysaccharide (LPS) and hyperoside were used to treat HT22 cells. The cell viability was measured by MTT assay. The cell apoptosis rate was measured by flow cytometry assay. The mRNA expression levels of interleukin-1ß (IL-1ß), interleukin-6 (IL-6), interleukin-8 (IL-8), and tumor necrosis factor-α (TNF-α) were determined by quantitative reverse transcription polymerase chain reaction. The levels of oxidative stress indices superoxide dismutase (SOD), reactive oxygen species (ROS), catalase (CAT), glutathione (GSH), and malondialdehyde (MDA) were measured by the kits. The expression of neurotrophic factor and the relationship among hyperoside, silent mating type information regulation 2 homolog-1 (SIRT1) and Wnt/ß-catenin, and sonic hedgehog was examined by western blotting. In the LPS-induced HT22 cells, hyperoside promotes cell survival; alleviates the level of IL-1ß, IL-6, IL-8, TNF-α, ROS, MDA, Bax, and caspase-3; and increases the expression of CAT, SOD, GSH, Bcl-2, BDNF, TrkB, and NGF. In addition, hyperoside upregulated the expression of SIRT1. Further mechanistic investigation showed that hyperoside alleviated LPS-induced inflammation, oxidative stress, and apoptosis by upregulating SIRT1 to activate Wnt/ß-catenin and sonic hedgehog pathways. Taken together, our data suggested that hyperoside acts as a protector in neuroinflammation.

Combined overexpression of SIRT1 and knockout of GCN5 in adult skeletal muscle does not affect glucose homeostasis or exercise performance in mice.

Sirtuin 1 (SIRT1) and general control of amino acid synthesis 5 (GCN5) regulate mitochondrial biogenesis via opposing modulation of peroxisome proliferator-activated receptor-γ coactivator 1α (PGC-1α) acetylation status and activity. However, the combined contribution of SIRT1 and GCN5 to skeletal muscle metabolism and endurance performance in vivo is unknown. In this study, we investigated the impact of combined skeletal muscle-specific overexpression of SIRT1 and deletion of GCN5 on glucose homeostasis, skeletal muscle mitochondrial biogenesis and function, and metabolic adaptation to endurance exercise training in mice. We generated mice with combined and tamoxifen-inducible skeletal muscle-specific overexpression of SIRT1 and knockout of GCN5 (dTG) and floxed [wild type (WT)] littermates using a Cre-LoxP approach. All mice were treated with tamoxifen at 5-6 wk of age, and 4-7 wk later glucose homeostasis, skeletal muscle contractile function, mitochondrial function, and the effects of 14 days of voluntary wheel running on expression of metabolic proteins and exercise capacity were assessed. There was no difference in oral glucose tolerance, skeletal muscle contractile function, mitochondrial abundance, or maximal respiratory capacity between dTG and WT mice. Additionally, there were no genotype differences in exercise performance and markers of mitochondrial biogenesis after 14 days of voluntary wheel running. These results demonstrate that combined overexpression of SIRT1 and loss of GCN5 in vivo does not promote metabolic remodeling in skeletal muscle of sedentary or exercise-trained mice.

The Clinical Significance of miR-135b-5p and Its Role in the Proliferation and Apoptosis of Hippocampus Neurons in Children with Temporal Lobe Epilepsy.

Temporal lobe epilepsy (TLE) is the most familiar localized epilepsy in children. MicroRNAs (miRNAs) are essential for the inhibition or promotion of numerous diseases. This study aimed to detect the expression of miR-135b-5p and primarily uncover its underlying function and mechanism in children with TLE. Quantitative real-time polymerase chain reaction was used to evaluate the expression of miR-135b-5p in children with TLE and in a rat model of epilepsy. MTT assay and flow cytometric apoptosis assay were conducted to evaluate the effects of miR-135b-5p on cell viability and apoptosis. Additionally, the dual luciferase reporter assay was performed to confirm the direct target of miR-135b-5p. Our data showed that the expression of miR-135b-5p was significantly decreased in children with TLE and in the epileptic rat neuron model. The dysregulation of miR-135b-5p could serve as a promising diagnostic biomarker for children with TLE. The overexpression of miR-135b-5p moderated the adverse influence on cell viability and apoptosis induced by magnesium-free medium. SIRT1 was identified as a target gene of miR-135b-5p. These results proved that miR-135b-5p might serve as a potential diagnostic biomarker in children with TLE. Overexpression of miR-135b-5p alleviates the postepileptic influence on cell viability and apoptosis by targeting SIRT1.

Sirtuin1 expression and survival in endometrial and clear-cell uterine cancer.

Several risk factors like obesity and hyperlipidemia were described for endometrial cancer. Here, the nuclear NAD-dependent histone-deacetylase Sirtuin1 (SIRT1) seems to be important. SIRT1 is also involved in cell regulatory mechanisms and can serve as tumor promotor or suppressor. Its role in tumor biology is not clear yet. In this study, we evaluated and correlated the SIRT1 expression with patients' tumor characteristics in endometrioid and clear-cell cancer of the uterus. 65 paraffin-embedded samples of patients with endometrial and clear-cell cancer of the uterus were immunohistochemically stained and SIRT1 expression was evaluated by immunoreactive score. The results were correlated to clinical and pathological tumor characteristics as well as to the expression of ARID1A and ß-Catenin. The staining was significantly more intensive in uterine endometrioid carcinoma compared to uterine clear-cell carcinoma (p = 0.007). The expression of SIRT1 correlated significantly with the membranous expression of ß-Catenin (p = 0.028) and ARID1A (p = 0.021). Patients with positive Sirtuin1 expression had a significantly better progression-free survival (p = 0.042), the overall survival showed a trend towards a better prognosis (p = 0.070). SIRT1 expression seems to be associated with improved progression-free survival in uterine cancer (endometrioid and clear-cell) and is correlated to the tumor suppressors ß-Catenin and ARID1A. Further studies are necessary to elucidate the role of SIRT1 in uterine and ovarian cancer and its potential as a therapeutic target.

3,4,5-Trihydroxycinnamic Acid Inhibits LPS-Induced Inflammatory Response by Increasing SIRT1 Expression in Human Umbilical Vein Endothelial Cells.

3,4,5-Trihydroxycinnamic acid (THC) has been demonstrated to exert anti-inflammatory activities in LPS-induced RAW264.7 murine macrophage cells and in LPS-induced septic mice. However, the effect of THC on the inflammatory response in vascular endothelial cells has not been clearly examined. The goal of the present study was to elucidate the anti-inflammatory properties of THC and its underlying mechanism in LPS-challenged human umbilical vein endothelial cells (HUVECs). THC significantly suppressed LPS-induced interleukin-1ß production and intercellular adhesion molecule-1 and vascular cell adhesion molecule-1 expression and significantly decreased LPS-induced nuclear factor-κB activation by attenuating p65 phosphorylation and inhibitor of kappa B degradation. To understand the underlying mechanism of the anti-inflammatory effect of THC, the involvement of the sirtuin 1 (SIRT1) signaling pathway was examined. THC resulted in increased expression of SIRT1 in LPS-challenged HUVECs. Among the downstream molecular targets of SIRT1, the level of LPS-induced acetylated p53 was significantly decreased by THC treatment, whereas no noticeable change was observed in the levels of forkhead box O3 and peroxisome proliferator activated receptor gamma coactivator 1 alpha. In conclusion, the results clearly demonstrate that THC possesses anti-inflammatory properties by increasing SIRT1 expression and subsequent suppression of p53 activation in LPS-challenged HUVECs.

Resveratrol protects retinal ganglion cell axons through regulation of the SIRT1-JNK pathway.

It is reported that Ischemia and reperfusion damage (I/R damage) can lead to retinal ganglion cell (RGC) death and neurodegeneration, which in turn can lead to irreversible vision loss. In this study, we sought to understand the neuroprotective effect of resveratrol, the important activator of sirtuin1 (SIRT1), on RGC survival in I/R damage model and the molecular mechanism that mediate this effect. Our results show that resveratrol could reverse axonal swelling, holes, and the chaos of the nucleus in axons of RGCs caused by I/R. At the same time, resveratrol could also reverse the activation of retinal astrocytes and the loss of RGCs caused by I/R. Resveratrol increased the expression of SIRT1 while decreasing the phosphorylation of N-terminal kinase (JNK). SP600125(JNK inhibitor) decreased the phosphorylation of JNK while increasing the expression of SIRT1, indicating that SIRT1 and JNK can interact with each other. Simultaneous administration of resveratrol and sirtinol (SIRT1 inhibitor) neither increased the expression of SIRT1 nor decreased the phosphorylation of JNK, indicating that resveratrol affects the phosphorylation of JNK by SIRT1. In total, our research shows that resveratrol treatment significantly reduces apoptosis and axonal degeneration of RGCs, and this protection is partly mediated through the SIRT1-JNK pathway.

TRB3 stimulates SIRT1 degradation and induces insulin resistance by lipotoxicity via COP1.

Fatty acid-induced lipotoxicity plays an important role in the pathogenesis of diabetes mellitus. Our previous studies have documented that lipotoxicity contributes to the onset and development of diabetes via insulin resistance and/or compromised function of the pancreatic ß-cells. However, the underlying molecular mechanisms associating lipotoxicity with insulin resistance remain to be fully elucidated. In this study, we explored the role of TRB3-COP1-SIRT1 in lipotoxicity leading to insulin resistance in hepatocytes. High fat diet (HFD)-fed mice and hepG2 cells stimulated with palmitate were utilized as models of lipid metabolism disorders. We analyzed the interactions of SIRT1 and COP1 with each other and with TRB3 using co-immunoprecipitation, western blotting. SIRT1 ubiquitination was also explored. Animal and cell experiments showed that lipotoxicity induced SIRT1 down-regulation at the protein level without altering the mRNA level, whereas, lipotoxicity led to up-regulation of TRB3 and COP1 at both the gene and protein levels. Mechanistic analysis indicated that COP1 functioned as an E3 Ub-ligase of SIRT1, responsible for its proteasomal degradation under lipotoxic conditions. TRB3 recruited COP1 to SIRT1 to promote its ubiquitination. Our data indicated for the first time that TRB3-COP1-SIRT1 pathway played an important role in lipotoxicity leading to insulin resistance in hepatocytes, and suggested that COP1 could be a potential therapeutic choice for the treatment of diabetes mellitus, with lipotoxicity being the important pathomechanism.

Ubiquitin-Specific Protease 22/Silent Information Regulator 1 Axis Plays a Pivotal Role in the Prognosis and 5-Fluorouracil Resistance in Hepatocellular Carcinoma.

BACKGROUND: Ubiquitin-specific protease 22 (USP22) is described as a key subunit of the Spt-Ada-Gcn5 acetyl transferase complex, which plays an important role in the prognosis and resistance to chemotherapy drugs in hepatocellular carcinoma (HCC). Silent information regulator 1 (SIRT1) is a member of the sirtuin family that is deubiquitinated by USP22. However, it is still unknown whether USP22 and SIRT1 co-expression is associated with disease progression and 5-Fluorouracil (5-FU) resistance in HCC. METHODS: 141 patients who received hepatectomy at our hospital from January 2010 to December 2014 were enrolled in this study. The expression of USP22 and SIRT1 was detected by immunohistochemical staining. Clinicopathological features, including age, gender, tumor number, tumor size, tumor differentiation, tumor stage, alpha-fetoprotein and microscopic vascular invasion, were assessed. Further experiments confirmed the role of SIRT1 in 5-FU drug resistance in vivo. RESULTS: Immunohistochemical staining showed that the high expression of USP22 and SIRT1 was frequently observed in HCC tissues relative to normal liver tissues. Overexpression of USP22 is associated with microscopic vascular invasion (MVI). Further analysis showed that the co-expression of USP22 and SIRT1 was more effective in predicting the prognosis of HCC. The SIRT1 inhibitor EX-527 dramatically inhibited the expression of Cyclin B1 and resistance-associated protein 3 (MRP3) to reduce 5-FU drug resistance in vivo. CONCLUSION: These findings suggest that the co-expression of USP22 and SIRT1 is significantly associated with unfavorable HCC progression. The inhibition of SIRT1 in vivo could be valuable in improving 5-FU drug sensitivity and inhibiting tumor cell proliferation and inducing apoptosis.

Latifolin Inhibits Oxidative Stress-Induced Senescence via Upregulation of SIRT1 in Human Dermal Fibroblasts.

Latifolin, a natural flavonoid found in Dalbergia odorifera T. Chen, has been reported to exhibit anti-inflammatory and anticarcinogenic activities in vitro. However, the anti-aging effects of latifolin are unknown. In this study, we selected a model in vitro system, hydrogen peroxide (H2O2)-induced senescence in human dermal fibroblasts (HDFs), to examine the protective effects of latifolin against senescence and the detailed molecular mechanisms involved. Latifolin reversed the senescence-like phenotypes of the oxidant-challenged model, including senescence-associated ß-galactosidase (SA-ß-gal) staining, cell proliferation, and the expression of senescence-related proteins, such as caveolin-1, ac-p53, p21Cip1/WAF1, p16Ink4α, pRb, and cyclinD1. We also found that latifolin induced the expression of silent information regulator 1 (SIRT1) in a concentration- and time-dependent manner, and the anti-senescence effect of latifolin was abrogated by SIRT1 inhibition. Latifolin also suppressed the activation of Akt and S6K1 and attenuated the increase in SA-ß-gal activity after H2O2 exposure. Our results indicate that latifolin exerts protective effects against senescence in HDFs and that induction of SIRT1 and inhibition of the mammalian target of rapamycin (mTOR) pathway are key mediators of its anti-aging effects.

Inherited disorders of cobalamin metabolism disrupt nucleocytoplasmic transport of mRNA through impaired methylation/phosphorylation of ELAVL1/HuR.

The molecular mechanisms that underlie the neurological manifestations of patients with inherited diseases of vitamin B12 (cobalamin) metabolism remain to date obscure. We observed transcriptomic changes of genes involved in RNA metabolism and endoplasmic reticulum stress in a neuronal cell model with impaired cobalamin metabolism. These changes were related to the subcellular mislocalization of several RNA binding proteins, including the ELAVL1/HuR protein implicated in neuronal stress, in this cell model and in patient fibroblasts with inborn errors of cobalamin metabolism and Cd320 knockout mice. The decreased interaction of ELAVL1/HuR with the CRM1/exportin protein of the nuclear pore complex and its subsequent mislocalization resulted from hypomethylation at R-217 produced by decreased S-adenosylmethionine and protein methyl transferase CARM1 and dephosphorylation at S221 by increased protein phosphatase PP2A. The mislocalization of ELAVL1/HuR triggered the decreased expression of SIRT1 deacetylase and genes involved in brain development, neuroplasticity, myelin formation, and brain aging. The mislocalization was reversible upon treatment with siPpp2ca, cobalamin, S-adenosylmethionine, or PP2A inhibitor okadaic acid. In conclusion, our data highlight the key role of the disruption of ELAVL1/HuR nuclear export, with genomic changes consistent with the effects of inborn errors of Cbl metabolisms on brain development, neuroplasticity and myelin formation.