| 2021 | Understanding the role of histone deacetylase and their inhibitors in neurodegenerative disorders: Current targets and future perspective. | Curr Neuropharmacol | Neurodegenerative diseases are the group of pathological conditions that cause motor inc-ordination (jerking movements), cognitive and memory impairments result due to degeneration of neurons in a specific area of the brain. Oxidative stress, mitochondrial dysfunction, excitotoxicity, neuroinflammation, neurochemical imbalance and histone deacetylase enzymes (HDAC) are known to play a crucial role in neurodegeneration. HDAC is classified into four categories (class I, II, III and class IV) depending upon their location and functions. HDAC1 and 2 are involved in neurodegeneration while HDAC3-11 and class III HDACs are beneficial as neuroprotective. HDACs are localized in different parts of the brain- HDAC1 (hippocampus and cortex), HDAC2 (nucleus), HDAC3, 4, 5, 7 and 9 (nucleus and cytoplasm), HDAC6 & HDAC7 (cytoplasm) and HDAC11 (Nucleus, Cornus ammonis 1 and spinal cord). In pathological conditions, HDAC up-regulates glutamate, phosphorylation of tau, and glial fibrillary acidic proteins while down-regulates BDNF, Heat shock protein 70, Gelsolin. Class III HDACs are divided into seven sub-classes (SIRT1-SIRT7). Sirtuins are localized in the different parts of the brain and neuron -Sirt1 (nucleus), Sirt2 (cortex, striatum, hippocampus and spinal cord), Sirt3 (mitochondria and cytoplasm), Sirt4, Sirt5 & Sirt6 (mitochondria), Sirt7 (nucleus) and Sirt8 (nucleolus). SIRTs (1, 3, 4, and 6) are involved in neuronal survival, proliferation and modulating stress response, and SIRT2 is associated with Parkinsonism, Huntington disease and Alzheimer's disease, whereas, SIRT6 is only associated with Alzheimer's disease. In this critical review, we have discussed the mechanisms and therapeutic targets of HDACs would be beneficial for the management of neurodegenerative disorders. |
| 2021 | Sirtuin 2 expression levels may predict the progression of sepsis survivors to chronic critical illness. | Ann Transl Med | Sirtuin 2 () is a conserved deacetylase that participates in the regulation of inflammation in sepsis. In this observational prospective study, we investigated the predictive value of the expression level in the development of chronic critical illness (CCI) in patients with sepsis.A total of 128 critically ill patients with sepsis or septic shock were enrolled and assigned to the CCI group, rapid recovery (RAP) group, or early death group according to their clinical trajectories. Patients' demographic and clinical information, as well as laboratory data, including C-reactive protein (CRP) level and total lymphocyte counts, were collected. Blood samples were obtained at admission and on days 1, 4, 7, 10, 14, and 21 (days 14 and 21 for the CCI group only). Peripheral blood mononuclear cells were isolated, and expression was measured by real-time polymerase chain reaction. Serum levels of interleukin (IL)-6 and IL-10 were measured by enzyme-linked immunosorbent assay.Our cohort included 37 CCI and 82 RAP patients, and 9 early death patients, who died within 14 days of intensive care unit (ICU) admission. Compared with the RAP group, CCI patients showed elevated CRP and IL-6 levels throughout the observation period, reflecting a sustained inflammatory response. However, decreases in total lymphocyte count and IL-10 expression in these patients were indicative of immunosuppression. mRNA level was lower in CCI and RAP patients compared with healthy controls at the initial stage of hospitalization, but increased starting on day 4 and continued to increase for the duration of hospitalization. By day 10, expression had almost returned to normal in RAP patients; however, in CCI patients, it continued to increase until the end of the observation period. A receiver-operating characteristic curve analysis showed that the expression level of at 10 days predicts the occurrence of CCI (P<0.05).expression may be a useful marker for identifying sepsis survivors who are at risk of progressing to CCI. |
| 2021 | Ethanol Exposure Attenuates Immune Response in Sepsis via Sirtuin 2 Expression. | Alcohol Clin Exp Res | Sepsis and septic shock kill over 270,000 patients per year in the United States. Sepsis transitions from a hyper-inflammatory to a hypo-inflammatory phase. Alcohol dependence is a risk factor for mortality from sepsis. Ethanol (EtOH) exposure impairs pathogen clearance through mechanisms that are not fully understood. Sirtuin 2 (SIRT2) interferes with pathogen clearance in immune cells but its role in the effects of EtOH on sepsis is unknown. We studied the effect of EtOH exposure on hyper- and hypo-inflammation and the role of SIRT2 in mice.We exposed C57Bl/6 (WT) mice to EtOH via drinking water and used intraperitoneal cecal slurry (CS)-induced sepsis to study: (i) 7-day survival, (ii) leukocyte adhesion (LA) in the mesenteric microcirculation during hyper- and hypo-inflammation, (iii) peritoneal cavity bacterial clearance, and (iv) SIRT2 expression in peritoneal macrophages. Using EtOH-exposed and lipopolysaccharide (LPS)-stimulated RAW 264.7 (RAW) cell macrophages for 4 hours or 24 hours, we studied: (i) tumor necrosis factor-α (TNF-α), interleukin-6 (IL-6), interleukin-10 (IL-10), and SIRT2 expression, and (ii) the effect of the SIRT2 inhibitor AK-7 on inflammatory response at 24 hours. Lastly, we studied the effect of EtOH on sepsis in whole body Sirt2 knockout (SIRT2KO) mice during hyper- and hypo-inflammation, bacterial clearance, and 7-day survival.WT EtOH-sepsis mice showed: (i) Decreased survival, (ii) Muted LA in the microcirculation, (iii) Lower plasma TNF-α and IL-6 expression, (iv) Decreased bacterial clearance, and (v) Increased SIRT2 expression in peritoneal macrophages versus vehicle-sepsis. EtOH-exposed LPS-stimulated RAW cells showed: (i) Muted TNF-α, IL-6, and increased IL-10 expression at 4 hours, (ii) endotoxin tolerance at 24 hours, and (iii) reversal of endotoxin tolerance with the SIRT2 inhibitor AK-7. EtOH-exposed SIRT2KO-sepsis mice showed greater 7-day survival, LA, and bacterial clearance than WT EtOH-sepsis mice.EtOH exposure decreases survival and reduces the inflammatory response to sepsis via increased SIRT2 expression. SIRT2 is a potential therapeutic target in EtOH with sepsis. |
| 2020 | Proteomic analysis of the monkey hippocampus for elucidating ischemic resistance. | J Clin Biochem Nutr | It is well-known that the cornu 1 (CA1) sector of hippocampus is vulnerable for the ischemic insult, whereas the dentate gyrus (DG) is resistant. Here, to elucidate its underlying mechanism, alternations of protein oxidation and expression of DG in the monkey hippocampus after ischemia-reperfusion by the proteomic analysis were studied by comparing CA1 data. Oxidative damage to proteins such as protein carbonylation interrupt the protein function. Carbonyl modification of molecular chaperone, heat shock 70 kDa protein 1 (Hsp70.1) was increased remarkably in CA1, but slightly in DG. In addition, expression levels of nicotinamide adenine dinucleotide (NAD)-dependent protein deacetylase sirtuin-2 (SIRT2) was significantly increased in DG after ischemia, but decreased in CA1. Accordingly, it is likely that SIRT2 upregulation and negligible changes of carbonylation of Hsp70.1 exert its neuroprotective effect in DG. On the contrary, carbonylation level of dihydropyrimidinase related protein 2 (DRP-2) and l-lactate dehydrogenase B chain (LDHB) were slightly increased in CA1 as shown previously, but remarkably increased in DG after ischemia. It is considered that DRP-2 and LDHB are specific targets of oxidative stress by ischemia insult and high carbonylation levels of DRP-2 may play an important role in modulating ischemic neuronal death. |
| 2020 | The clinical significance of the SIRT2 expression level in the early stage of sepsis patients. | Ann Palliat Med | Sirtuin2 (SIRT2), one of the members of the sirtuins family, has been proven to be a conserved protein. SIRT2 is reported to be associated with infection and inflammation, and its expression level in some cells such as mice brain can be reduced by the stimulation of lipopolysaccharide (LPS). We surmise that the expression levels of SIRT2 may be a warning signal of sepsis in the human body.A total of 38 intensive care units (ICU) patients with a diagnosis of sepsis/septic shock were recruited within 24 h of entry into the ICU. Serum procalcitonin (PCT), hypersensitive C-reactive protein (hs-CRP), and SIRT2 measurements were performed on admission, and on the second and fourth therapy days. The mRNA expression of SIRT2 was detected by real-time polymerase chain reaction (PCR).We ascertained that the expression levels of SIRT2 mRNA in sepsis patients and septic shock patients were lower than those in the healthy volunteer control group (P<0.001); On the first day, the septic shock patients showed a lowered expression of SIRT2 mRNA than the sepsis patients did (P<0.001), but there were no significantly differences on the following days. In the receiver operating characteristic (ROC) curves for sepsis, the area under the curve (AUC) of SIRT2 mRNA expression was larger than the AUC of PCT and hs-CRP. Furthermore, the sensitivity of SIRT2 was higher than that of PCT and hs-CRP, but the specificity of SIRT2 was higher than that of hs-CRP and lower than that of PCT.The data demonstrate that sepsis and septic shock patients have a decreased expression level of SIRT2 mRNA, and thus SIRT2 may be a potential biomarker for the diagnosis of sepsis, akin to PCT and hs-CRP. |
| 2020 | SIRT2 suppresses expression of inflammatory factors via Hsp90-glucocorticoid receptor signalling. | J Cell Mol Med | SIRT2 is a NAD -dependent deacetylase that deacetylates a diverse array of protein substrates and is involved in many cellular processes, including regulation of inflammation. However, its precise role in the inflammatory process has not completely been elucidated. Here, we identify heat-shock protein 90α (Hsp90α) as novel substrate of SIRT2. Functional investigation suggests that Hsp90 is deacetylated by SIRT2, such that overexpression and knock-down of SIRT2 altered the acetylation level of Hsp90. This subsequently resulted in disassociation of Hsp90 with glucocorticoid receptor (GR), and translocation of GR to the nucleus. This observation was further confirmed by glucocorticoid response element (GRE)-driven reporter assay. Nuclear translocation of GR induced by SIRT2 overexpression repressed the expression of inflammatory cytokines, which were even more prominent under lipopolysaccharide (LPS) stimulation. Conversely, SIRT2 knock-down resulted in the up-regulation of cytokine expression. Mutation analysis indicated that deacetylation of Hsp90 at K294 is critical for SIRT2-mediated regulation of cytokine expression. These data suggest that SIRT2 reduces the extent of LPS-induced inflammation by suppressing the expression of inflammatory factors via SIRT2-Hsp90-GR axis. |
| 2018 | Sirtuins and Immuno-Metabolism of Sepsis. | Int J Mol Sci | Sepsis and septic shock are the leading causes of death in non-coronary intensive care units worldwide. During sepsis-associated immune dysfunction, the early/hyper-inflammatory phase transitions to a late/hypo-inflammatory phase as sepsis progresses. The majority of sepsis-related deaths occur during the hypo-inflammatory phase. There are no phase-specific therapies currently available for clinical use in sepsis. Metabolic rewiring directs the transition from hyper-inflammatory to hypo-inflammatory immune responses to protect homeostasis during sepsis inflammation, but the mechanisms underlying this immuno-metabolic network are unclear. Here, we review the roles of NAD+ sensing Sirtuin (SIRT) family members in controlling immunometabolic rewiring during the acute systemic inflammatory response associated with sepsis. We discuss individual contributions among family members SIRT 1, 2, 3, 4 and 6 in regulating the metabolic switch between carbohydrate-fueled hyper-inflammation to lipid-fueled hypo-inflammation. We further highlight the role of SIRT1 and SIRT2 as potential "druggable" targets for promoting immunometabolic homeostasis and increasing sepsis survival. |
| 2019 | Cysteine thiol oxidation on SIRT2 regulates inflammation in obese mice with sepsis. | Inflammation | Obesity increases morbidity and mortality in acute illnesses such as sepsis and septic shock. We showed previously that the early/hyper-inflammatory phase of sepsis is exaggerated in obese mice with sepsis; sirtuin 2 (SIRT2) modulates sepsis inflammation in obesity. Evidence suggests that obesity with sepsis is associated with increased oxidative stress. It is unknown whether exaggerated hyper-inflammation of obesity with sepsis modulates the SIRT2 function in return. We showed recently that SIRT6 oxidation during hyper-inflammation of sepsis modulates its glycolytic function. This study tested the hypothesis that increased oxidative stress and direct SIRT2 oxidation exaggerate hyper-inflammation in obesity with sepsis. Using spleen and liver tissue from mice with diet-induced obesity (DIO) we studied oxidized vs. total SIRT2 expression during hyper- and hypo-inflammation of sepsis. To elucidate the mechanism of SIRT2 oxidation (specific modifications of redox-sensitive cysteines) and its effect on inflammation, we performed site-directed mutations of redox-sensitive cysteines Cys221 and Cys224 on SIRT2 to serine (C221S and C224S), transfected HEK293 cells with mutants or WT SIRT2, and studied SIRT2 enzymatic activity and NFĸBp65 deacetylation. Finally, we studied the effect of SIRT2 mutation on LPS-induced inflammation using RAW 264.7 macrophages. In an inverse relationship, total SIRT2 decreased while oxidized SIRT2 expression increased during hyper-inflammation and SIRT2 was unable to deacetylate NFĸBp65 with increased oxidative stress of obesity with sepsis. Mechanistically, both the mutants (C221S and C224S) show decreased (1) SIRT2 enzymatic activity, (2) deacetylation of NFĸBp65, and (3) anti-inflammatory activity in response to LPS vs. WT SIRT2. Direct oxidation modulates SIRT2 function during hyper-inflammatory phase of obesity with sepsis via redox sensitive cysteines. |
| 2018 | The application of gene marker-assisted selection and proteomics for the best meat quality criteria and body measurements in Qinchuan cattle breed. | Mol Biol Rep | In the past few decades, enhancement of animal productivity has been gaining increasing attention among decisions-makers, politicians, mangers, and breeders, because of the increasing of world population and shortage of natural resources. The selection of high productivity animals is the main goal, through the application of genetic improvement programs. The use of molecular genetics has conferred significant breeding advantages over conventional breeding techniques. In this regard, many economic characteristics are controlled by a small number of multiple gene loci, each of which is responsible for trait diversity and hence they are referred to as quantitative trait loci (QTL). Single-nucleotide polymorphisms (SNPs), which have recently been discovered through DNA sequencing, are considered one of the most useful types of genetic marker. SNPs are found where different nucleotides occur at the same position in the DNA sequence. They are found in both coding and noncoding regions of the genome and are present at one SNP in every 1000 b. Strategies for the identification and application of markers are based on reference to examples of loci that can control various traits. Furthermore, markers for growth, body measurements, and meat quality traits are preferred, because they can be used to predict the performance of animals, via blood samples, in the first few days of animal life. Marker-assisted selection using SNPs, such asSIRT1, SIRT2, LPL, CRTC2, SIX4, UCPs, and ZBTB38as selection criteria of body measurements and meat traits in beef cattle, will be beneficial in selection and breeding programs. The proteomic is a novel marker and a new approache of biotechnology which increases the understanding of the biological processes, besides being a remarkable biomarker that interrelated to growth and meat quality traits. Proteomics is a vigorous tool as usage for deduces molecular processes between quality traits and muscle proteins, which are helpful in analyzing the mechanisms of biochemistry that influence quality. So they could be potential biomarker for some meat quality traits. Among them, Actin, Myosin, Heat shock proteins are used a novel approaches in the field of biotechnology to understand the proteomics changes. This review article highlights the novel findings on the potential use of MAS and proteomics as biomarker for the selection for meat quality and carcass traits in Qinchuan cattle breed. |
| 2017 | Sirtuin 2 Deficiency Increases Bacterial Phagocytosis by Macrophages and Protects from Chronic Staphylococcal Infection. | Front Immunol | Sirtuin 2 (SIRT2) is one of the seven members of the family of NAD-dependent histone deacetylases. Sirtuins target histones and non-histone proteins according to their subcellular localization, influencing various biological processes. SIRT2 resides mainly in the cytoplasm and regulates cytoskeleton dynamics, cell cycle, and metabolic pathways. As such, SIRT2 has been implicated in the pathogenesis of neurodegenerative, metabolic, oncologic, and chronic inflammatory disorders. This motivated the development of SIRT2-directed therapies for clinical purposes. However, the impact of SIRT2 on antimicrobial host defense is largely unknown. Here, we address this question using SIRT2 knockout mice. We show that SIRT2 is the most highly expressed sirtuin in myeloid cells, especially macrophages. SIRT2 deficiency does not affect immune cell development and marginally impacts on intracellular signaling and cytokine production by splenocytes and macrophages. However, SIRT2 deficiency enhances bacterial phagocytosis by macrophages. In line with these observations, in preclinical models, SIRT2 deficiency increases survival of mice with chronic staphylococcal infection, while having no effect on the course of toxic shock syndrome toxin-1, LPS or TNF-induced shock, fulminant peritonitis, sub-lethal pneumonia, and chronic candidiasis. Altogether, these data support the safety profile of SIRT2 inhibitors under clinical development in terms of susceptibility to infections. |
| 2017 | Sirtuin 2 Regulates Microvascular Inflammation during Sepsis. | J Immunol Res | . Sepsis and septic shock, the leading causes of death in noncoronary intensive care units, kill more than 200,000/year in the US alone. Circulating cell-endothelial cell interactions are the rate determining factor in sepsis inflammation. Sirtuin, a seven-member family of proteins (SIRT1-7), epigenetically controls inflammation. We have studied the roles of SIRTs 1, 3, and 6 in sepsis previously. In this project, we studied the role of SIRT2 on sepsis-related inflammation. . Sepsis was induced in C57Bl/6 (WT), SIRT2 knockout (SIRT2KO), and SIRT2 overexpressing (SIRT2KI) mice by cecal ligation and puncture (CLP). We studied leukocyte/platelet adhesion using intravital microscopy and E-selectin/ICAM-1 adhesion molecule expression in the small intestine with immunohistochemistry (IHC) six hours post-CLP/sham surgery. We also studied 7-day survival rates in WT, SIRT2KO, and SIRT2KI sepsis mice. . Compared to WT mice, SIRT2KO mice show exaggeration while SIRT2KI mice show attenuation of cellular adhesion with sepsis in the small intestine. We also show that the small intestinal E-selectin and ICAM-1 expressions increased in SIRT2KO and decreased in SIRT2KI mice versus those in WT sepsis mice. We show that the 7-day survival rate is decreased in SIRT2KO and increased in SIRT2KI sepsis mice. . SIRT2 modulates microvascular inflammation in sepsis and affects survival. |
| 2016 | HSPB1 Enhances SIRT2-Mediated G6PD Activation and Promotes Glioma Cell Proliferation. | PLoS One | Heat shock proteins belong to a conserved protein family and are involved in multiple cellular processes. Heat shock protein 27 (Hsp27), also known as heat HSPB1, participates in cellular responses to not only heat shock, but also oxidative or chemical stresses. However, the contribution of HSPB1 to anti-oxidative response remains unclear. Here, we show that HSPB1 activates G6PD in response to oxidative stress or DNA damage. HSPB1 enhances the binding between G6PD and SIRT2, leading to deacetylation and activation of G6PD. Besides, HSPB1 activates G6PD to sustain cellular NADPH and pentose production in glioma cells. High expression of HSPB1 correlates with poor survivalrate of glioma patients. Together, our study uncovers the molecular mechanism by which HSPB1 activates G6PD to protect cells from oxidative and DNA damage stress. |
| 2016 | Effects of intrinsic aerobic capacity, aging and voluntary running on skeletal muscle sirtuins and heat shock proteins. | Exp Gerontol | Sirtuins are proteins that connect energy metabolism, oxidative stress and aging. Expression of heat shock proteins (Hsps) is regulated by heat shock factors (HSFs) in response to various environmental and physiological stresses, such as oxidative stress. Oxidative stress accumulates during aging which makes cells more prone to DNA damage. Although many experimental animal models have been designed to study the effects of knockdown or overexpression of sirtuins, HSFs and Hsps, little is known about how aging per se affects their expression. Here we study the impact of intrinsic aerobic capacity, aging and voluntary exercise on the levels of sirtuins, HSFs and Hsps in skeletal muscle.We studied the protein levels of sirtuins (SIRT1, SIRT2, SIRT3, SIRT4, SIRT5, SIRT6 and SIRT7), HSF1, HSF2, Hsp10, Hsp27 and Hsp70 before and after one-year of voluntary running intervention of rat strains selectively bred for intrinsic aerobic exercise capacity; high capacity runners (HCR) and low capacity runners (LCR) differ by more than 30% for median lifespan. This setup enabled us to discern the effects of inborn aerobic capacity, aging and exercise activity on the protein levels of sirtuins, HSFs and Hsps in skeletal muscle.Our results revealed that the longer lived HCR rats had higher SIRT3, HSF1 and HSF2 contents in skeletal muscle (gastrocnemius, p < 0.05) than LCRs. Neither aging nor voluntary running had a significant effect on the studied sirtuin proteins. Aging significantly increased the protein levels of HSF1, HSF2 and Hsp27 (p < 0.05).Our finding of elevated SIRT3 levels in HCR rats is in line with previous studies; SIRT3 in general is linked to elevated fatty acid oxidation and oxidative phosphorylation, which previously have been associated with metabolic profile of HCRs. HSF1, HSF2 and Hsp27 levels increased with aging, showing that aged muscles responded to aging-related stress. Our study shows for the first time that SIRT3 protein level is linked to high inborn aerobic capacity, and may be directly interconnected to longevity. |
| 2015 | Selective Inhibition of SIRT2 Improves Outcomes in a Lethal Septic Model. | Curr Mol Med | Seven isoforms of histone deacetylase Class III have been reported - Sirtuin (SIRT) 1-7. We recently demonstrated that EX-527, an inhibitor of SIRT1, reduces mortality in a mouse model of lethal-cecal-ligationand- puncture (CLP)-induced septic shock. Our present study was aimed at determining whether selective inhibition of SIRT2, with AGK2, would decrease animal death and attenuate the inflammatory response in a septic model.Experiment I: C57BL/6J mice were intraperitoneally given either AGK2 (82 mg/kg) in dimethyl sulfoxide (DMSO) or DMSO alone, and 2 h later subjected to CLP. Survival was monitored for 240 hours. Experiment II: mice treated the same way as Experiment I, were grouped into (i) DMSO vehicle, and (ii) AGK2, with sham mice (operating but without any treatment) serving as controls. Peritoneal fluid and peripheral blood were examined at 24 and 48 hours for cytokine production. Samples of blood at 48 h were also allocated to assess coagulability using Thrombelastography (TEG). Morphological changes of bone marrow were evaluated from long bones (femurs and tibias) with hematoxylin and eosin (H&E) staining. Bone marrow atrophy was quantified by a blinded pathologist. Experiment III: cytokines in supernatant of the cultured normal primary splenocytes were measured after the cells were stimulated by lipopolysaccharide and treated with or without AGK2 (10 µM) for 6 hours.AGK2 significantly reduced mortality and decreased levels of cytokines in blood (TNF-α: 298.3±24.6 vs 26.8±2.8 pg/ml, p=0.0034; IL-6: 633.4±82.8 vs 232.6±133.0 pg/ml, p=0.0344) and peritoneal fluid (IL-6: 704.8±67.7 vs 391.4±98.5 pg/ml, p=0.033) compared to vehicle control. Also, AGK2 suppressed the TNF-α and IL-6 production in the cultured splenocytes (TNF-α: 68.1±6.4 vs 23.9±2.8 pg/ml, p=0.0009; IL-6: 73.1±4.2 vs 49.6±3.0 pg/ml; p=0.0051). The TEG data showed that the mice subjected to CLP displayed prolonged fibrin formation and fibrin cross-linkage time, slower clot formation, decreased platelet function, and clot rigidity. AGK2 treatment was associated with dramatic improvements in fibrin cross-linkage and clot formation times, without a significant impact on the clot initiation parameters or platelet function. Additionally, AGK2 significantly attenuated the bone marrow atrophy (58.3±6.5 vs 30.0±8.2%, p=0.0262).Selective inhibition of SIRT2 significantly improves survival, and attenuates sepsis-associated "cytokine storm", coagulopathy, and bone marrow atrophy in a mouse model of lethal septic shock. |
| 2015 | Cold acclimation increases levels of some heat shock protein and sirtuin isoforms in threespine stickleback. | Comp Biochem Physiol A Mol Integr Physiol | Molecular chaperones [heat shock proteins (HSPs)] increase in response to rapid changes in temperatures, but long-term acclimation to cold temperature may also warrant elevations in HSPs. In fishes, cold acclimation increases mitochondrial density and oxidative stress in some tissues, which may increase demand for HSPs. We hypothesized that levels of HSPs, as well as sirtuins (SIRTs), NAD-dependent deacetylases that mediate changes in metabolism and responses to oxidative stress (including increases in HSPs), would increase during cold acclimation of threespine stickleback (Gasterosteus aculeatus). Transcript levels of hsp70, hsc70, hsp60 and hsp90-α, sirts1-4, as well as protein levels of HSP60, HSP90 and HSC70 were quantified in liver and pectoral adductor muscle of stickleback during cold acclimation from 20 °C to 8 °C. In liver, cold acclimation stimulated a transient increase in mRNA levels of hsp60 and hsc70. Transcript levels of sirt1 and sirt2 also increased in response to cold acclimation and remained elevated. In pectoral muscle, mRNA levels of hsp60, hsp90-α, hsc70 and sirt1 all transiently increased in response to cold acclimation, while levels of sirts2-4 remained constant or declined. Similar to transcript levels, protein levels of HSC70 increased in both liver and pectoral muscle. Levels of HSP90 also increased in liver after 4 weeks at 8 °C. HSP60 remained unchanged in both tissues, as did HSP90 in pectoral muscle. Our results indicate that while both HSPs and SIRTs increase in response to cold acclimation in stickleback, the response is tissue and isoform specific, likely reflecting differences in metabolism and oxidative stress. |
| 2015 | Proteomic and Mitochondrial Genomic Analyses of Pediatric Brain Tumors. | Mol Neurobiol | The molecular mechanism unraveling why a particular type of pediatric brain tumor (pBT) behaves so differently from child to child or genetic/epigenetic changes in the mitochondrial genome vary from tumor to tumor is not clearly understood. Despite the identification of mitochondrial DNA (mtDNA) mutations in different types of pBT, the contribution of mitochondrial dysfunction-related genes or proteins that are selectively up- or down-regulated in pBT of different types has not been comprehensively examined. In the present study, we combined a 2D DIGE approach with protein identification using MALDI-TOF MS and LC-MS/MS, coupled with mtDNA genomics to screen brain samples for discovering changes in protein expression, and mtDNA sequence variation and mtDNA copy number in the disease states. Two-dimensional gel electrophoresis-based differential proteomic analysis of the brain tumors showed that 116 proteins were found to be up- or down-regulated in brain tumors. Some of the proteins up-regulated in tumors compared to controls were dihydropyrimidinase-like 2; glial fibrillary acidic protein isoform 2; phosphoserine aminotransferase isoform 1; Sirt2 histone deacetylase; and C10orf2 protein, mitochondrial DNA helicase. Proteins down-regulated in brain tumors compared to controls were heat shock protein 90 kDa beta, BiP; guanine nucleotide binding protein (G protein), beta polypeptide 2-like 1, isoform CRA_d; histone H2B.1; neurofilament, light polypeptide 68 kDa; Annexin I; and RAN. These differentially expressed proteins may provide useful information for developing molecular markers of diagnostic or prognostic value. To investigate further the role of mitochondrial dysfunction, we examined the effects of mtDNA copy number, oxidative damage, and mtDNA variants as independent or combined risk factors for the development of pBTs. Bayesian network and mechanistic hierarchical structure Markov Chain Monte Carlo (MCMC) modeling were used to analyze the relationship between these variables. The combined effects of G3196, 9952A, 10006G, 100398G, oxidative mtDNA damages, and mtDNA copy number increased the probability of developing brain tumors in female children by 51 times more when compared to normal incidence of pediatric brain tumors. Comparison of mechanistic structure models also supported the finding that female children who have the wild type allele G3196, variant allele 9952A, variant allele 10006G, variant allele10398A, and high mtDNA copy number had increased probability of developing pediatric brain tumors. Estimation of nuclear genes controlling mitochondrial biogenesis and development of brain, cortical dysplasia, and the effect of the environment using MCMC method showed that these latent variables had a very significant contribution in the development of pediatric brain tumors. Together, these results suggest that mitochondrial genome and tumor proteome are important contributors to brain tumor risk in children, and findings from this study may guide the prospects for targeting mitochondria for therapeutic treatment of childhood brain tumor. |
| 2014 | Rosuvastatin Modulates the Post-Translational Acetylome in Endothelial Cells. | Acta Cardiol Sin | Statins are lipid-lowering drugs that can simultaneously evoke pleiotropic effects on cardioprotection, vasodilation, and diabetes prevention. Recently, statins have been reported to be able to activate the AMP-activated protein kinase, thereby up-regulating sirtuin (SIRT) that functions as non-histone deacetylases. Therefore, it is essential to investigate the post-translational acetylome that might explain the mechanism of statin-modulated pleiotropic effects.Endothelial cells EAhy 926 treated with rosuvastatin were used to monitor the expression of SIRTs proteins. The protein lysates of both mock- and rosuvastatin-treated cells were further separated by two- dimensional gel electrophoresis coupled with western blotting analysis. The significantly changed acetyl- containing proteins detected by using an anti-acetyl lysine antibody were collected from another preparative gel for mass spectrometric assay to identify the acetylated site in the proteins.Rosuvastatin treatment was shown to increase the SIRT1 expression when compared with SIRT2. Among 100 detected proteins with acetylated signal, 12 showed an increased level of acetylation, whereas 6 showed a decreased level of acetylation (deacetylation). The acetylated lysine (K) sites of 3 heat shock proteins, i.e., HSP47/K(165), HSP70/K(380), and heat shock-inducible protein/K(417), were determined. We also found that beta-filamin, elongation factor, galectin and hCG22067 have 2 acetylated lysine sites in their peptide sequences. These dynamic acetylations might alter the protein's function and are thought to be important in regulating statin-mediated pleiotropic effect.Our study provided a feasible methodology for detecting acetylated proteins. This acetylome information may be utilized to explain, at least partially, the mechanisms of statin-derived pleiotropic effects.Acetylation/deacetylation; Acetylome; Endothelial cell; Proteomics; Rosuvastatin; Sirtuin. |
| 2013 | The sirtuin inhibitor cambinol impairs MAPK signaling, inhibits inflammatory and innate immune responses and protects from septic shock. | Biochim Biophys Acta | Sirtuins (SIRT1-7) are NAD(+)-dependent histone deacetylases (HDACs) that play an important role in the control of metabolism and proliferation and the development of age-associated diseases like oncologic, cardiovascular and neurodegenerative diseases. Cambinol was originally described as a compound inhibiting the activity of SIRT1 and SIRT2, with efficient anti-tumor activity in vivo. Here, we studied the effects of cambinol on microbial sensing by mouse and human immune cells and on host innate immune responses in vivo. Cambinol inhibited the expression of cytokines (TNF, IL-1β, IL-6, IL-12p40, and IFN-γ), NO and CD40 by macrophages, dendritic cells, splenocytes and whole blood stimulated with a broad range of microbial and inflammasome stimuli. Sirtinol, an inhibitor of SIRT1 and SIRT2 structurally related to cambinol, also decreased macrophage response to TLR stimulation. On the contrary, selective inhibitors of SIRT1 (EX-527 and CHIC-35) and SIRT2 (AGK2 and AK-7) used alone or in combination had no inhibitory effect, suggesting that cambinol and sirtinol act by targeting more than just SIRT1 and SIRT2. Cambinol and sirtinol at anti-inflammatory concentrations also did not inhibit SIRT6 activity in in vitro assay. At the molecular level, cambinol impaired stimulus-induced phosphorylation of MAPKs and upstream MEKs. Going well along with its powerful anti-inflammatory activity, cambinol reduced TNF blood levels and bacteremia and improved survival in preclinical models of endotoxic shock and septic shock. Altogether, our data suggest that pharmacological inhibitors of sirtuins structurally related to cambinol may be of clinical interest to treat inflammatory diseases. |