Targeting SIRT1 Research Articles

MHY2251, a New SIRT1 Inhibitor, Induces Apoptosis via JNK/p53 Pathway in HCT116 Human Colorectal Cancer Cells.

Sirtuins (SIRTs) belong to the nicotinamide adenine dinucleotide (NAD+)-dependent class III histone deacetylase family. They are key regulators of cellular and physiological processes, such as cell survival, senescence, differentiation, DNA damage and stress response, cellular metabolism, and aging. SIRTs also influence carcinogenesis, making them potential targets for anticancer therapeutic strategies. In this study, we investigated the anticancer properties and underlying molecular mechanisms of a novel SIRT1 inhibitor, MHY2251, in human colorectal cancer (CRC) cells. MHY2251 reduced the viability of various human CRC cell lines, especially those with wild-type TP53. MHY2251 inhibited SIRT1 activity and SIRT1/2 protein expression, while promoting p53 acetylation, which is a target of SIRT1 in HCT116 cells. MHY2251 treatment triggered apoptosis in HCT116 cells. It increased the percentage of late apoptotic cells and the sub-G1 fraction (as detected by flow cytometric analysis) and induced DNA fragmentation. In addition, MHY2251 upregulated the expression of FasL and Fas, altered the ratio of Bax/Bcl-2, downregulated the levels of pro-caspase-8, -9, and -3 proteins, and induced subsequent poly(ADP-ribose) polymerase cleavage. The induction of apoptosis by MHY2251 was related to the activation of the caspase cascade, which was significantly attenuated by pre-treatment with Z-VAD-FMK, a pan-caspase inhibitor. Furthermore, MHY2251 stimulated the phosphorylation of c-Jun N-terminal kinase (JNK), and MHY2251-triggered apoptosis was blocked by pre-treatment with SP600125, a JNK inhibitor. This finding indicated the specific involvement of JNK in MHY2251-induced apoptosis. MHY2251 shows considerable potential as a therapeutic agent for targeting human CRC via the inhibition of SIRT1 and activation of JNK/p53 pathway.

Antitumor, toxicity and target gene expression evaluation of MiR-204-5p mimic application on melanoma b16-bearing mice

Objective. To evaluate anti-tumor, toxic effect of miR-204-5p mimic applicaton on melanoma B-16-bearing mice followed by miR-204-5p target gene expression estimation in melanoma tumor and distant organs. Material and Methods. C57Bl/6 melanoma B-16-bearing mice were used. The animals of the experimental group were intraperitoneally injected with a 5 nM miR-204-5p miRNA simulator (mimic) on the 8th, 10th, and 12th days after melanoma B-16 cell transplantation. Based on the results of bioinformatic analysis, miR-204-5p target genes BCL2 and SIRT1 expression levels were determined by quantitative real-time PCR. The toxic effect of miR-204-5p mimic was estimated by the evaluation of body weight, mass of the internal organs, and motor activity. Results. On the 13-14th days of the experiment, the motor activity of animals in the control groups decreased signifcantly compared to the group of animals treated by miR-204-5p. Target gene BCL2 showed increased expression in the lungs and kidneys and SIRT1 levels were increased in the lungs of miR-204-5p mimic treated animals (p˂0.05). Tumor mass tended to decrease in the animals treated by miR-204-5p mimic. Conclusion. Modulation of the level of miR-204-5p microRNA led to changes in the expression of SIRT1 and BCL2 in the lungs of animals, and changes in the expression of BCL2in the kidneys. MiR-204-5p mimic application did not have toxic effect on animals treated. Further studies are necessary to clarify miR-204-5p implication in melanoma cell proliferation regulation as well as it’s biodistibution in the tumor tissue.

Isoliquiritigenin mitigates oxidative damage after subarachnoid hemorrhage in vivo and in vitro by regulating Nrf2-dependent Signaling Pathway via Targeting of SIRT1

BackgroundOxidative stress is a crucial factor leading to subarachnoid hemorrhage (SAH)-induced early brain injury (EBI). Isoliquiritigenin has been verified as a powerful anti-oxidant in a variety of diseases models and can activate sirtuin 1 and nuclear factor-erythroid 2-related factor 2 (Nrf2) pathways. However, the effects of isoliquiritigenin against EBI after SAH and the underlying mechanisms remain elusive. PurposeThe primary goal of this study is to verify the therapeutic effects of isoliquiritigenin on EBI after SAH and the possible molecular mechanisms. Study designA prechiasmatic cistern SAH model in rats and a hemoglobin incubation SAH model in primary neurons were established. Isoliquiritigenin was administered after SAH induction. EX527 was employed to inhibit sirtuin 1 activation and ML385 was used to suppress Nrf2 signaling. MethodsIn our study, neurological scores, brain edema, biochemical estimation, western blotting, and histopathological study were performed to explore the therapeutic action of isoliquiritigenin against SAH. ResultsOur data revealed that isoliquiritigenin significantly mitigated oxidative damage after SAH as evidenced by decreased reactive oxygen species overproduction and enhanced intrinsic anti-oxidative system. Concomitant with the reduced oxidative insults, isoliquiritigenin improved neurological function and reduced neuronal death in the early period after SAH. Additionally, isoliquiritigenin administration significantly enhanced Nrf2 and sirtuin 1 expressions. Inhibition of Nrf2 by ML385 reversed the anti-oxidative and neuroprotective effects of isoliquiritigenin against SAH. Moreover, inhibiting sirtuin 1 by EX527 pretreatment suppressed isoliquiritigenin-induced Nrf2-dependent pathway and abated the cerebroprotective effects of isoliquiritigenin. In primary cortical neurons, isoliquiritigenin treatment also ameliorated oxidative insults and repressed neuronal degeneration. The beneficial aspects of isoliquiritigenin were attributed to the promotion of sirtuin 1 and Nrf2 signaling pathways and were counteracted by EX527. ConclusionOur findings suggest that isoliquiritigenin exerts cerebroprotective effects against SAH-induced oxidative insults by modulating the Nrf2-mediated anti-oxidant signaling in part through sirtuin 1 activation. Isoliquiritigenin might be a new potential drug candidate for SAH.

TARGETING SIRT1 RESCUES AGE- AND OBESITY-INDUCED HUMAN MICROVASCULAR DYSFUNCTION

Objective: Experimental evidence suggests a relevant role of SIRT1 in age- and metabolic-related vascular dysfunction. Whether these effects hold true in the human microvasculature is unknown. We aimed to investigate the role of SIRT1 in age- and obesity-related microvascular dysfunction in humans. Design and method: Individuals (n = 95) undergoing laparoscopic surgery were stratified by BMI status (above or below 30 Kg/m2) and age (above or below 40 years) and classified as young control (YC), young obese (YO), old control (OC) and old obese (OO). Endothelial function was assessed in small resistance arteries by pressurized micromyography, before and after incubation with a SIRT1 agonist (SRT1720) and a mitochondria reactive oxygen species (mtROS) scavenger (MitoTEMPO). We assessed vascular levels of mtROS and nitric oxide availability by confocal microscopy and vascular gene expression of SIRT1 and mitochondrial proteins by qPCR. ChIP assay was employed to investigate SIRT1-dependent epigenetic regulation of mitochondrial proteins. Results: Endothelial function showed a graded decrease from YC to OO, with reduced nitric oxide availability and increased mtROS levels. Similarly, SIRT1 and mitochondrial antioxidant proteins (FOXO3 and SOD2) expression levels were reduced while there was a higher expression of pro-oxidant and ageing mitochondria proteins p66Shc and Arginase II. OO, YO and OC endothelial function was rescued by SRT1720 (Figure). The improvement in endothelial function showed a linear relationship with age, BMI and vascular emodelling. The restoration was comparable to the one obtained with mitoTEMPO in the same groups. These effects were explained by SIRT1-dependent chromatin changes leading to reduced p66Shc expression and upregulation of proteins involved in mitochondria respiratory chain: ATP synthase 6, cytochrome B, NADH dehydrogenase 2, NADH dehydrogenase 5. Conclusions: Restoring SIRT1 activity rescues obesity and age-related endothelial dysfunction. Its epigenetic control on mitochondrial pathways influences mtROS levels, NO availability, and the expression of the mitochondria respiratory chain proteins. SIRT1 is a novel central regulator of a homeostatic axis connecting vascular phenotype to systemic metabolism and ageing and to exposure to external adverse stimuli. Early targeting of SIRT1 might represent a crucial strategy to prevent the microvascular dysfunction related to age and obesity.

MiR-34a-5p/Sirt1 axis: A novel pathway for puerarin-mediated hepatoprotection against benzo(a)pyrene

Benzo[a]pyrene (BaP) as a carcinogen induces oxidative stress and inflammation, causing health problems including liver damage. Puerarin (a natural flavonoid) is traditionally used to provide hepatoprotective effects. This research was established to meet the rising demand for effective therapies/treatments against hepatic diseases and investigate the mechanism underlying the protective actions of puerarin against BaP-induced liver damage. In mice, puerarin combated effectively the detrimental changes in liver weight, color and function indices caused by BaP. In HepG2 cells, puerarin alleviated BaP-induced cell death, oxidative stress and inflammation, and such effects were positively correlated with puerarin's concentration (12.5–50 μM). Mechanistic studies revealed that BaP induced low Sirt1 expression and high miR-34a-5p expression, and puerarin treatment alleviated these changes. Oxidative stress and inflammation induced by BaP were almost eliminated when miR-34a-5p was silenced. Inhibiting miR-34a-5p or overexpressing Sirt1 had a similar effect to puerain treatment. Overexpression of miR-34a-5p and inhibition of Sirt1 reduced the protective effect of puerarin. Collectively, miR-34a-5p participates in the regulation of puerarin's protective function against BaP-induced injury through targeting Sirt1. There is a novel pathway for suppressing oxidative stress and inflammation via miR-34a-5p/Sirt1 axis in puerarin-mediated hepatoprotection, which opens up a new avenue for alternative therapies.

Targeting Sirt1, AMPK, Nrf2, CK2, and Soluble Guanylate Cyclase with Nutraceuticals: A Practical Strategy for Preserving Bone Mass.

There is a vast pre-clinical literature suggesting that certain nutraceuticals have the potential to aid the preservation of bone mass in the context of estrogen withdrawal, glucocorticoid treatment, chronic inflammation, or aging. In an effort to bring some logical clarity to these findings, the signaling pathways regulating osteoblast, osteocyte, and osteoclast induction, activity, and survival are briefly reviewed in the present study. The focus is placed on the following factors: the mechanisms that induce and activate the RUNX2 transcription factor, a key driver of osteoblast differentiation and function; the promotion of autophagy and prevention of apoptosis in osteoblasts/osteoclasts; and the induction and activation of NFATc1, which promotes the expression of many proteins required for osteoclast-mediated osteolysis. This analysis suggests that the activation of sirtuin 1 (Sirt1), AMP-activated protein kinase (AMPK), the Nrf2 transcription factor, and soluble guanylate cyclase (sGC) can be expected to aid the maintenance of bone mass, whereas the inhibition of the serine kinase CK2 should also be protective in this regard. Fortuitously, nutraceuticals are available to address each of these targets. Sirt1 activation can be promoted with ferulic acid, N1-methylnicotinamide, melatonin, nicotinamide riboside, glucosamine, and thymoquinone. Berberine, such as the drug metformin, is a clinically useful activator of AMPK. Many agents, including lipoic acid, melatonin, thymoquinone, astaxanthin, and crucifera-derived sulforaphane, can promote Nrf2 activity. Pharmacological doses of biotin can directly stimulate sGC. Additionally, certain flavonols, notably quercetin, can inhibit CK2 in high nanomolar concentrations that may be clinically relevant. Many, though not all, of these agents have shown favorable effects on bone density and structure in rodent models of bone loss. Complex nutraceutical regimens providing a selection of these nutraceuticals in clinically meaningful doses may have an important potential for preserving bone health. Concurrent supplementation with taurine, N-acetylcysteine, vitamins D and K2, and minerals, including magnesium, zinc, and manganese, plus a diet naturally high in potassium, may also be helpful in this regard.

Depletion of the miR-34a “sponge” MALAT1 in aging skeletal muscle: Implications for age-related muscle loss

Abstract We have recently shown that increased levels of reactive oxygen species (ROS) in aging skeletal muscle are associated with increased expression of the senescence-associated microRNA miR-34a-5p (miR-34a). The histone deacetylase Sirt1 is a validated target of miR-34a, and miR-34a expression is induced by the tumor suppressor p53 which is itself stimulated by ROS. Long noncoding RNAs (lncRNAs) are known to function as “sponges” for microRNAs, but the role of such competing endogenous RNAs (ceRNA) in muscle aging is not well understood. We therefore examined in skeletal muscles of young (4-6 mos) and aged (22-24) male and female mice the expression of several lncRNAs that are predicted to bind miR-34a-5p in silico and whose predicted binding has been validated experimentally. Results indicate a significant decrease in lncRNA MALAT1 expression with aging. MALAT1 is known to be highly expressed during the later stages of myoblast differentiation and myotube maturation. We therefore treated C2C12 cells at 48 hrs with hydrogen peroxide (10 uM) and examined changes in MALAT1 expression. MALAT1 was significantly decreased with H2O2 treatment, whereas miR-34a is increased in C2C12 cells after hydrogen peroxide exposure. Age-related muscle atrophy mediated by ROS may therefore result in part from related mechanisms involving miR-34a activity: an increase in miR-34a targeting Sirt1 resulting from p53 activation and an increase in miR-34a bioavailability resulting from a decline in miR-34a “sponging” due to ceRNA MALAT1 depletion. These findings suggest that therapeutic interventions increasing MALAT1 expression in muscle may potentially enhance the preservation of muscle mass with aging.

Depletion of the miR-34a “sponge” MALAT1 in aging skeletal muscle: Implications for age-related muscle loss

We have recently shown that increased levels of reactive oxygen species (ROS) in aging skeletal muscle are associated with increased expression of the senescence-associated microRNA miR-34a-5p (miR-34a). The histone deacetylase Sirt1 is a validated target of miR-34a, and miR-34a expression is induced by the tumor suppressor p53 which is itself stimulated by ROS. Long noncoding RNAs (lncRNAs) are known to function as “sponges” for microRNAs, but the role of such competing endogenous RNAs (ceRNA) in muscle aging is not well understood. We therefore examined in skeletal muscles of young (4-6 mos) and aged (22-24) male and female mice the expression of several lncRNAs that are predicted to bind miR-34a-5p in silico and whose predicted binding has been validated experimentally. Results indicate a significant decrease in lncRNA MALAT1 expression with aging. MALAT1 is known to be highly expressed during the later stages of myoblast differentiation and myotube maturation. We therefore treated C2C12 cells at 48 hrs with hydrogen peroxide (10 uM) and examined changes in MALAT1 expression. MALAT1 was significantly decreased with H2O2 treatment, whereas miR-34a is increased in C2C12 cells after hydrogen peroxide exposure. Age-related muscle atrophy mediated by ROS may therefore result in part from related mechanisms involving miR-34a activity: an increase in miR-34a targeting Sirt1 resulting from p53 activation and an increase in miR-34a bioavailability resulting from a decline in miR-34a “sponging” due to ceRNA MALAT1 depletion. These findings suggest that therapeutic interventions increasing MALAT1 expression in muscle may potentially enhance the preservation of muscle mass with aging.

The effect and mechanism of cypermethrin-induced hippocampal neurotoxicity as determined by network pharmacology analysis and experimental validation

ABSTRACT Cypermethrin (CMN) is a widely used artificial synthetic pesticide that causes neurotoxicity in the hippocampus. However, the underlying toxicological targets and mechanisms remain unclear. In this study, network pharmacology analysis and in vitro models were integrated to investigate the effect and mechanism of CMN-induced hippocampal neurotoxicity. A total of 88 targets of CMN-induced hippocampal neurotoxicity were predicted. Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes enrichment (KEGG) analyses suggested that these targets were related to multiple GO terms and signaling pathways. To further investigate underlying mechanism, the top 10 hub targets (Akt1, Tnf, Ptgs2, Casp3, Igf1, Sirt1, Jun, Cat, Il10, and Bcl2l1) were screened. Furthermore, cell viability and lactate dehydrogenase (LDH) assays demonstrated that CMN was toxic to HT22 cells in a time- and dose-dependent manner. Terminal deoxynucleotidyl transferase dUTP nick end labeling (TUNEL) staining revealed that treatment with CMN increased the proportion of apoptotic cells. In addition, the real-time quantitative polymerase chain reaction (RT-qPCR) results indicated that CMN altered the mRNA expression levels of most of the hub targets, with the exceptions of Igf1 and Jun. The results demonstrated that multiple targets and signaling pathways were involved in CMN-induced hippocampal neurotoxicity. These findings provided reference values for subsequent studies of the toxicological mechanism of CMN.

MiR-376a inhibits glioma proliferation and angiogenesis by regulating YAP1/VEGF signalling via targeting of SIRT1

BackgroundGlioma is the most common cancer in the central nervous system. Previous studies have revealed that the miR-376 family is crucial in tumour development; however, its detailed mechanism in glioma is not clear. MethodsCellular mRNA or protein levels of miR-376a, SIRT1, VEGF and YAP1 were detected via qRT–PCR or Western blotting. We analysed the proliferation, angiogenesis and migration abilities of glioma cell lines using colony formation, tube formation and Transwell assays. A luciferase assay was performed to determine whether miR-376a could recognize SIRT1 mRNA. Xenograft experiments were performed to analyse the tumorigenesis capacity of glioma cell lines in nude mice. The angiogenesis marker CD31 in xenograft tumours was detected via immunohistochemistry (IHC). ResultsmiR-376a expression was lower in glioma cells than in normal astrocytes. miR-376a mimic inhibited SIRT1, YAP1, and VEGF expression and suppressed the proliferation, migration and angiogenesis abilities of the glioma cell lines LN229 and A172, whereas miR-376a inhibitor exerted the opposite functions. In a luciferase assay, miR-376a inhibited the luciferase activity of WT-SIRT1. SIRT1 overexpression upregulated YAP1 and VEGF in glioma cells and promoted proliferation, migration and angiogenesis. Xenografts with ectopic miR-376a expression exhibited lower volumes and weights and a slower growth curve. Overexpression of miR-376a inhibited YAP1/VEGF signalling and angiogenesis by inhibiting SIRT1 in xenograft tissues. ConclusionmiR-376a directly targets and inhibits SIRT1 in glioma cells. Downregulation of SIRT1 resulted in decreased YAP1 and VEGF signalling, which led to suppression of glioma cell proliferation, migration and angiogenesis.

Cadmium induces ferroptosis and apoptosis by modulating miR-34a-5p/Sirt1axis in PC12 cells.

Cadmium (Cd) is a potent neurotoxic metal present in the environment and food. In this study, CdCl2 (2 or 4μM) induced cytotoxicity and neurotoxicity in PC12 cells, causing decreases in cell viability and NEP protein expression and increase in p-tau protein expression. For the first time, CdCl2 -initiated injury was found to result from the induction of not only apoptosis but also ferroptosis, as evidenced by the increased iron content, ROS production, and mitochondrial membrane potential along with changes in the expressions of iron death-related genes (FTH1, GPX4, ASCL4, PTGS2, and NOX1) and levels of caspase9, Bax, and Bcl-2 proteins. The molecular mechanisms leading to apoptosis and ferroptosis at least included the participation of the miR-34a-5p/Sirt1 axis, in which miR-34a-5p promoted CdCl2 -induced neurotoxicity through targeting Sirt1. Knocking out miR-34a-5p attenuated CdCl2 -induced damage of PC12 cells, cytotoxicity and neurotoxicity. This research provides the underlying molecular mechanisms of CdCl2 -induced damage and asserts the role of miRNAs as critical regulators.

Berberine Potentiates Insulin Secretion and Prevents β-cell Dysfunction Through the miR-204/SIRT1 Signaling Pathway.

Pancreatic β-cell dysfunction is a key link during the progression of type 2 diabetes (T2DM), and SIRT1 participates in the regulation of various physiological activities of islet β-cells. However, as a key link in signal transduction, it is not clear how SIRT1 is regulated. By TargetScan prediction, we found that miR-204, which is enriched in islets, has highly complementary binding sites with SIRT1. Therefore, we speculate that miR-204 may be the upstream regulatory target of SIRT1 in islets and thus participate in the occurrence of β-cell dysfunction. In this study, we explored the association between miR-204 and β-cell dysfunction, the therapeutic effects of berberine (BBR) on β-cell function and the possible mechanisms. We found that miR-204 increased and SIRT1 mRNA and protein levels decreased significantly in islets both in vivo and in vitro. MIN6 cells induced by palmitic acid exhibited increased apoptosis, and the accumulation of insulin and ATP in the supernatant decreased. Importantly, palmitic acid treatment combined with miR-204 silencing showed opposite changes. MiR-204 overexpression in MIN6 cells increased apoptosis and decreased insulin and ATP production and SIRT1 expression. SIRT1 overexpression reversed the damage to β-cells caused by miR-204. The BBR treatment effectively improved insulin synthesis, reduced miR-204 levels, and increased SIRT1 expression in islet tissue in diabetic mice. Overexpression of miR-204 reversed the protective effect of BBR on apoptosis and insulin secretion in MIN6 cells. Our study identifies a novel correlation between miR-204 and β-cell dysfunction in T2DM and shows that administration of BBR leads to remission of β-cell dysfunction by regulating the miR-204/SIRT1 pathway.

Circulating MicroRNAs in the Second Trimester From Pregnant Women Who Subsequently Developed Preeclampsia: Potential Candidates as Predictive Biomarkers and Pathway Analysis for Target Genes of miR-204-5p.

MicroRNAs (miRNAs) play an important role in the pathophysiology of preeclampsia (PE). However, the expression of circulating miRNAs was not analyzed in the second trimester of pregnancy, a period of major relevance to identify predictive biomarkers for PE. Therefore, we examined the expression profiles of 84 circulating miRNAs using a PCR array in plasma collected between 20 and 25 weeks of gestation from pregnant women, who subsequently developed PE and those who remained healthy during pregnancy, randomly selected from a prospective cohort. Overall, 23 miRNAs had a fold change > 2.0 and were considered to be upregulated in plasma from pregnant women who subsequently developed PE, even before the onset of clinical symptoms of PE. However, only miR-204-5p was statistically significant (P = 0.0082). Experimentally validated interactions for the target genes of miR-204-5p extracted from miRTarBase were used in the gene set functional enrichment analysis to identify Reactome pathways. The network connecting the 37 target genes for miR-204-5p revealed pathways of known pathophysiological relevance during the early development of PE and included key genes related to PE, such as BDNF, MMP-9, MALAT1, TGFBR2, and SIRT1. We further depicted downstream targets of SIRT1 that are related to the vascular endothelial function or implicated in the pathophysiology of PE, namely, FOXO1, NFκB, HIF-1α, NOS3, and PPAR-γ. Our novel findings provide for circulating miRNAs upregulated in the second trimester on plasma from pregnant women who subsequently developed PE that is potentially related to the early development of PE, which may guide further studies focused on the validation of potential predictive biomarkers in PE.

Butyl Benzyl Phthalate Promotes Adipogenesis in 3T3-L1 Cells via the miRNA-34a-5p Signaling Pathway in the Absence of Exogenous Adipogenic Stimuli.

Phthalates, a plasticizer group, are used extensively in many of the products we use every day. Public health concerns are growing as recent studies have implicated butyl benzyl phthalate (BBP) as an obesogen. However, BBP-induced epigenetic regulation during adipogenesis is still unknown. We investigated if BBP altered miR-34a-5p, a key miRNA involved in obesity, and regulated its downstream pathway. Differentiating 3T3-L1 cells were exposed to various doses of BBP without exogenous adipogenic stimuli, tested for adipogenesis markers (PPARγ and aP2), and stained for lipid accumulation with Oil Red O staining. We then measured the expression of miR-34a-5p and its target genes, Nampt and Sirt1, along with another significant epigenetic modulator, Sirt3. Furthermore, using antagomiR, we examined whether miR-34a-5p knockdown decreased adipogenesis. BBP exposure resulted in augmented expression levels of miR-34a-5p with an associated increase in adipogenesis. BBP significantly decreased the Nampt, Sirt1, and Sirt3 gene expression levels. However, a decrease in the protein expression was observed only for Nampt, indicating that miR-34a-5p under BBP exposure may regulate Sirt1/Sirt3 only at the transcriptional level. Interestingly, in the presence of BBP, knockdown of miR-34a-5p decreased adipogenesis in the differentiating 3T3-L1 cells. Furthermore, miR-34a-5p knockdown increased the Nampt protein expression levels as well as NAD+ levels, indicating that miR-34a-5p regulates Nampt during BBP exposure. Additionally, the NAD+-dependent sirtuin activity decreased in BBP-treated cells and increased in miR-34a-5p knockdown cells with BBP treatment. BBP exposure demonstrated the involvement of epigenetic regulation by altering the expression patterns of miR-34a-5p and its target Nampt, which may perturb the energy homeostasis of the differentiating adipocytes by altering NAD+ levels and sirtuin activity, resulting in increased adipogenesis.

Retracted] MicroRNA‑22 inhibits cell growth and metastasis in breast cancer via targeting of SIRT1

Following the publication of this paper, it was drawn to the Editors’ attention by a concerned reader that the western blotting data shown in Fig. 3B and D were strikingly similar to data appearing in different form in other articles by different authors. Owing to the fact that the contentious data in the above article had already been published elsewhere, or were already under consideration for publication, prior to its submission to <em>Experimental and Therapeutic Medicine</em>, the Editor has decided that this paper should be retracted from the Journal. The authors were asked for an explanation to account for these concerns, but the Editorial Office did not receive any reply. The Editor apologizes to the readership for any inconvenience caused. [the original article was published in <em>Experimental and Therapeutic Medicine</em> 14: 1009‑1016, 2017; DOI: 10.3892/etm.2017.4590]

MicroRNA-93-5p participates in type 2 diabetic retinopathy through targeting Sirt1.

To investigate the role of miR-93-5p in rats with type 2 diabetic retinopathy (DR) through targeting Sirt1. The targeting correlation between miR-93-5p and Sirt1 was validated by dual-luciferase reporter gene assay. Type 2 diabetes mellitus (T2DM) rat models were received intravitreal injection of antagomir NC (negative control), miR-93-5p antagomir, miR-93-5p agomir and/or recombinant Sirt1, followed by observation of pathological changes in retina via HE staining. Besides, retinal vascular permeability was determined by fluorescein isothiocyanate-bovine serum albumin (FITC-BSA), while the retinal vasculature was observed through retinal trypsin digestion. Expression of miR-93-5p and Sirt1 was measured by qRT-PCR and Western blotting, while the levels of VEGF, proinflammatory cytokines and anti-oxidative indicators were determined using corresponding kits. MiR-93-5p could target Sirt1 as analyzed by the luciferase reporter gene assay. Rats in the T2DM group presented the up-regulation of miR-93-5p and down-regulation of Sirt1 in the retina, and miR-93-5p inhibition could up-regulate Sirt1 expression in the T2DM rats. Recombinant Sirt1 decreased retinal vascular permeability and acellular capillaries with improved pathological changes in retina from T2DM rats, which was abolished by miR-93-5p agomir. Moreover, miR-93-5p inhibition or Sirt1 overexpression decreased the levels of VEGF and proinflammatory cytokines while enhancing the activity of anti-oxidative indicators. However, indicators above had no significant differences between T2DM group and T2DM + agomir + Sirt1 group. MiR-93-5p, via targeting Sirt1, could affect the vascular permeability and acellular capillaries and mitigate the inflammation and oxidative stress in the retinas, which may play a critical role in DR.

Pentacyclic Triterpenoid Saponins, Poterinasides A-J, from Silverweed Cinquefoil Roots Promising Hepatoprotective and Anti-inflammatory Agents.

Silverweed cinquefoil roots, as dietary supplements, foods, and medicines, are widely used in western areas of China, specifically in Tibet Autonomous Region and Gansu and Qinghai Provinces. In this paper, 10 new natural pentacyclic triterpenoid saponins (1-10), named poterinasides A-J, along with 14 known compounds (11-24) were isolated and purified from silverweed cinquefoil roots. The chemical structures of 1-10 were established by extensive analysis of 1D and 2D NMR data and mass spectrometric data. Poterinasides A (1), B (2), and G (7) with the unique position of substituents on the E ring had never been discovered in natural products before. Saponins 1-8, 14, and 22 displayed potent hepatoprotective activities, and 1-8, 10, 11, 14, 16, 19, and 22-24 showed outstanding anti-inflammatory effects. On the basis of the present results, some structure-activity relationships were summarized, in which 3α-OH, 19β-CH3, 20α-CH3, 20β-CH3, 21α-OH, and 30-OH groups in isolated pentacyclic triterpenoid saponins were found to strengthen the hepatoprotective and anti-inflammatory activities, respectively. Further, the following pharmacophore-based virtual screening and docking studies on special targets proteins, SIRT1 and COX-2, revealed roughly similar results with the structure-activity relationships, and this combination method was used for the first time for active natural compound screening.

Time-course miRNA alterations and SIRT1 inhibition triggered by adolescent lead exposure in mice.

Sirtuin 1 (SIRT1), the NAD-dependent histone deacetylase, has been extensively investigated due to its cognitive protective effect. Studies suggest microRNAs (miRNAs) and histone modifications are key epigenetic regulators of gene expression and play important role in brain development. We previously showed that cognitive impairment by lead (Pb) was associated with downregulation of SIRT1, but the epigenetic role of this is unclear. Thus, we exposed 4-week-old male mice to 0.2% lead acetate solution for three months, and subsequently extracted brain homogenate from mice cortex and hippocampus at the age of 1, 4, and 16 months, respectively. In this study, we found that the protein level of SIRT1 was inhibited in the hippocampus and cortex of 16-month-old aged mice exposed to Pb. Moreover, changes in the levels of miR-138-5p and miR-141-3p, which were considered to the mechanistic target of SIRT1 by bioinformatic analysis, were negative correlations SIRT1 protein expression. We also found miR-34c-3p expression was increased in the cortex of mice at the age of 16 months. Collectively, our results showed the expression of neural SIRT1 and three selected microRNAs at different age nodes of mice for the first time of following Pb exposure. Our results suggest that additional efforts should focus on the consequences of early Pb exposure from an epigenetic perspective.

Mir-140 and Mir-34a as Molecular Markers for Apoptotic Brain in Sunset Yellow and Carmoisine Intoxicated Mice

Brain is the central organ in human body, that is working 24hr/7days even before we leave our mother`s womb. None surprising that care should be paid for the food consumed that consequently affecting brain environment, neurotransmitters as well as oxidative state. Carmoisine (Car) and sunset yellow (SY) are synthetic food additives extensively utilized during food processing and subsequently affecting brain health. The apoptotic effect underling the behavioral changes after oral consumption of either Car or SY remains not fully understudied. Respective biochemical and molecular biological parameters by means of one fifty adult male mice were conducted. The study extended for 3 months on 5 different groups with ten mice each; Group 1 was utilized as the control group, group 2 was treated with the acceptable daily intake (ADI) of SY (30 mg/kg BW), group 3 was treated with 10x ADI of SY, group 4 was treated with ADI of Car (4 mg/kg BW) and group 5 was administered 10x ADI of Car; all doses were given orally via gastric lavage. Exposure to higher doses of either SY or Car significantly altered the biochemical parameters; decreased both serotonin and dopamine levels and total antioxidant capacity as well. However, increased the lipid peroxidation marker malonaldehyde (MDA), upregulated the mRNA expression of the pro-apoptotic genes (Fas, Fas-L, Bax and casp3) and down regulated the transcriptional level of the anti-apoptotic gene Bcl2.Moreover upregulated both miR-140 and miR-34a expression levels and consequently down-regulated their target genes NRF-2 and SIRT-1, respectively. So, we can conclude that excessive oral administration of either Car or SY has apoptotic effect and care should be paid with their usage.

Histone deficiency and accelerated replication stress in T cell aging.

With increasing age, individuals are more vulnerable to viral infections such as with influenza or the SARS-CoV-2 virus. One age-associated defect in human T cells is the reduced expression of miR-181a. miR-181ab1 deficiency in peripheral murine T cells causes delayed viral clearance after infection, resembling human immune aging. Here we show that naive T cells from older individuals as well as miR-181ab1-deficient murine T cells develop excessive replication stress after activation, due to reduced histone expression and delayed S-phase cell cycle progression. Reduced histone expression was caused by the miR-181a target SIRT1 that directly repressed transcription of histone genes by binding to their promoters and reducing histone acetylation. Inhibition of SIRT1 activity or SIRT1 silencing increased histone expression, restored cell cycle progression, diminished the replication-stress response, and reduced the production of inflammatory mediators in replicating T cells from old individuals. Correspondingly, treatment with SIRT1 inhibitors improved viral clearance in mice with miR-181a-deficient T cells after LCMV infection. In conclusion, SIRT1 inhibition may be beneficial to treat systemic viral infection in older individuals by targeting antigen-specific T cells that develop replication stress due to miR-181a deficiency.