Lysine deacetylases, like histone deacetylases (HDACs) and sirtuins (SIRTs), are involved in many regulatory processes such as control of metabolic pathways, DNA repair, and stress responses. Besides robust deacetylase activity, sirtuin isoforms SIRT2 and SIRT3 also show demyristoylase activity. Interestingly, most of the inhibitors described so far for SIRT2 are not active if myristoylated substrates are used. Activity assays with myristoylated substrates are either complex because of coupling to enzymatic reactions or time-consuming because of discontinuous assay formats. Here we describe sirtuin substrates enabling direct recording of fluorescence changes in a continuous format. Fluorescence of the fatty acylated substrate is different when compared to the deacylated peptide product. Additionally, the dynamic range of the assay could be improved by the addition of bovine serum albumin, which binds the fatty acylated substrate and quenches its fluorescence. The main advantage of the developed activity assay is the native myristoyl residue at the lysine side chain avoiding artifacts resulting from the modified fatty acyl residues used so far for direct fluorescence-based assays. Due to the extraordinary kinetic constants of the new substrates (KM values in the low nM range, specificity constants between 175,000 and 697,000 M-1s-1) it was possible to reliably determine the IC50 and Ki values for different inhibitors in the presence of only 50 pM of SIRT2 using different microtiter plate formats.

• Klíčová slova
• bovine serum albumin effect, continuous activity assay, fluorescence quenching, histone deacetylases, myristoylated substrates, sirtuin inhibitors, sirtuins,
• MeSH
• barvicí látky MeSH
• lysin MeSH
• peptidy MeSH
• sirtuin 1 metabolismus   MeSH
• sirtuin 2 metabolismus   MeSH
• sirtuin 3 * metabolismus   MeSH
• sirtuiny * metabolismus   MeSH
• Publikační typ
• časopisecké články MeSH
• Názvy látek
• barvicí látky MeSH
• lysin MeSH
• peptidy MeSH
• sirtuin 1 MeSH
• sirtuin 2 MeSH
• sirtuin 3 * MeSH
• sirtuiny * MeSH

Sirtuin activating compounds (STACs) attenuate various type of liver insults through mechanisms which are not fully understood. In the present study, we investigated the ameliorative potential of quercetin (natural polyphenol) and SRT1720 (synthetic SIRT1 activator) against D-galactosamine/lipopolysaccharide-induced hepatotoxicity (an experimental model of acute liver failure). Moreover, we compared and contrasted the roles of stress responsive enzymes, sirtuin 1 (SIRT1) and heme oxygenase 1 (HO-1) in hepatoprotection/ hepatotoxicity. Liver injury was induced in male Wistar rats by intraperitoneal injection of D-galactosamine (400 mg/kg) and lipopolysaccharide (10 microg/kg). Some animals were pretreated with quercetin (50 mg/kg i.p.) or SRT1720 (5 mg/kg i.p.). Twenty-four hours later, the effects of these treatments were evaluated by biochemical studies and Western blot. D-GalN/LPS treatment upregulated HO-1 expression, downregulated SIRT1 expression, decreased AST: ALT ratio and markedly increased bilirubin, catalase and conjugated diene levels. Pretreatment of D-GalN/LPS rats with either quercetin or SRT1720 returned SIRT1 expression, HO-1 expression and all the aforementioned markers towards normal. Collectively, these findings suggest that elevated HO-1 and low SIRT1 expressions are involved in the pathogenesis of D-GalN/LPS-induced hepatotoxicity. Drugs that downregulate HO-1 and/or upregulate SIRT1 seem to have antihepatotoxic effects and need further exploration.

• MeSH
• galaktosamin toxicita   MeSH
• hemová oxygenasa (decyklizující) antagonisté a inhibitory   metabolismus   MeSH
• heterocyklické sloučeniny tetra- a více cyklické farmakologie   terapeutické užití   MeSH
• krysa rodu Rattus MeSH
• lékové postižení jater farmakoterapie   metabolismus   MeSH
• lipopolysacharidy toxicita   MeSH
• náhodné rozdělení MeSH
• potkani Wistar MeSH
• sirtuin 1 metabolismus   MeSH
• zvířata MeSH
• Check Tag
• krysa rodu Rattus MeSH
• mužské pohlaví MeSH
• zvířata MeSH
• Publikační typ
• časopisecké články MeSH
• Názvy látek
• galaktosamin MeSH
• hemová oxygenasa (decyklizující) MeSH
• heterocyklické sloučeniny tetra- a více cyklické MeSH
• Hmox1 protein, rat MeSH Prohlížeč
• lipopolysacharidy MeSH
• Sirt1 protein, rat MeSH Prohlížeč
• sirtuin 1 MeSH
• SRT1720 MeSH Prohlížeč

D-Galactosamine/Lipopolysaccharide (D-GalN/LPS) is a well known model of hepatotoxicity that closely resembles acute liver failure (ALF) seen clinically. The role of sirtuin 1 in this model has not yet been documented. However, there have been a number of studies about the cytoprotective effects of resveratrol, a SIRT1 activator, in the liver. This study was aimed at elucidating the roles of SIRT1 protein expression or catalytic activity in D-GalN/LPS model of hepatotoxicity. ALF was induced in male Wistar rats by intraperitoneal injection of D-GalN and LPS. Some groups of animals were pretreated with resveratrol and/or EX-527 (SIRT1 inhibitor). The effects of these treatments were evaluated by biochemical and Western blot studies. D-GalN/LPS treatment was able to induce hepatotoxicity and significantly increase all markers of liver damage and lipid peroxidation. A dramatic decrease of SIRT1 levels in response to D-GalN/LPS treatment was also documented. Resveratrol pretreatment attenuated D-GalN/LPS-induced hepatotoxicity. EX-527 blocked the cytoprotective effects of resveratrol. However, both resveratrol and EX-527 pretreatments did not exhibit any significant effect on SIRT1 protein expression. Collectively, these results suggest that downregulation of SIRT1 expression is involved in the cytotoxic effects of D-GalN/LPS model and SIRT1 activity contributes to the cytoprotective effects of resveratrol in the liver.

• MeSH
• antioxidancia farmakologie   MeSH
• cytoprotekce MeSH
• down regulace MeSH
• galaktosamin * MeSH
• inhibitory enzymů farmakologie   MeSH
• játra účinky léků   enzymologie   patologie   MeSH
• karbazoly farmakologie   MeSH
• lékové postižení jater enzymologie   etiologie   patologie   prevence a kontrola   MeSH
• lipopolysacharidy * MeSH
• modely nemocí na zvířatech MeSH
• peroxidace lipidů účinky léků   MeSH
• potkani Wistar MeSH
• resveratrol MeSH
• sirtuin 1 antagonisté a inhibitory   metabolismus   MeSH
• stilbeny farmakologie   MeSH
• zvířata MeSH
• Check Tag
• mužské pohlaví MeSH
• zvířata MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH
• Názvy látek
• 6-chloro-2,3,4,9-tetrahydro-1H-carbazole-1-carboxamide MeSH Prohlížeč
• antioxidancia MeSH
• galaktosamin * MeSH
• inhibitory enzymů MeSH
• karbazoly MeSH
• lipopolysacharidy * MeSH
• resveratrol MeSH
• Sirt1 protein, rat MeSH Prohlížeč
• sirtuin 1 MeSH
• stilbeny MeSH

The present study was designed to evaluate the therapeutic potential of quercetin in a sub-chronic model of hepatotoxicity. The roles of putative antioxidant enzymes, sirtuin 1 (SIRT1) and heme oxygenase 1 (HO-1), in hepatoprotection were also addressed. Sub-chronic liver injury was induced in rats by intraperitoneal administration of 0.5 ml/kg carbon tetrachloride (CTC), once every 3 days, for 2 weeks. Some CTC rats were concurrently treated with 100 mg/kg quercetin, intragastrically, once every day, for 2 weeks. The effects of these drugs in the liver were evaluated by biochemical, histological, immunohistochemical and molecular biological studies. CTC triggered oxidative damage to the liver as unanimously shown by altered biochemical parameters and liver morphology. Furthermore, CTC highly upregulated HO-1 and SIRT1 expression levels. Concomitant treatment of rats with quercetin downregulated SIRT1 expression and ameliorated the hepatotoxic effects of CTC. However, quercetin did not have any significant effect on HO-1 expression and bilirubin levels. Collectively, these results suggest that the antioxidant and cytoprotective effects of quercetin in CTC treated rats were SIRT1 mediated and less dependent on HO-1. Thus, pharmacologic modulation of SIRT1 could provide a logic therapeutic approach in sub-chronic hepatotoxicity.

• Klíčová slova
• Carbon tetrachloride, Heme oxygenase 1, Hepatoprotection, Hepatotoxicity, Quercetin, Sirtuin 1,
• MeSH
• alanintransaminasa krev   MeSH
• aspartátaminotransferasy krev   MeSH
• bilirubin krev   MeSH
• down regulace účinky léků   MeSH
• hemoxygenasa-1 metabolismus   MeSH
• imunohistochemie MeSH
• játra metabolismus   patologie   MeSH
• krysa rodu Rattus MeSH
• ochranné látky farmakologie   MeSH
• otrava chloridem uhličitým metabolismus   patologie   prevence a kontrola   MeSH
• potkani Wistar MeSH
• quercetin farmakologie   MeSH
• sirtuin 1 metabolismus   MeSH
• upregulace účinky léků   MeSH
• zvířata MeSH
• Check Tag
• krysa rodu Rattus MeSH
• mužské pohlaví MeSH
• zvířata MeSH
• Publikační typ
• časopisecké články MeSH
• Názvy látek
• alanintransaminasa MeSH
• aspartátaminotransferasy MeSH
• bilirubin MeSH
• hemoxygenasa-1 MeSH
• ochranné látky MeSH
• quercetin MeSH
• sirtuin 1 MeSH

Sirtuin 1 (SIRT1) is involved in important biological processes such as energy metabolism and regulatory functions of the cell cycle, apoptosis, and inflammation. Our previous studies have shown hepatoprotective effect of polyphenolic compound resveratrol, which is also an activator of SIRT1. Therefore, the aim of our present study was to clarify the role of SIRT1 in process of hepatoprotection in animal model of drug-induced liver damage. Male Wistar rats were used for both in vivo and in vitro studies. Hepatotoxicity was induced by single dose of acetaminophen (APAP). Some rats and hepatocytes were treated by resveratrol or synthetic selective activator of sirtuin 1 (CAY10591). The degree of hepatotoxicity, the activity and expression of the SIRT1 were determined by biochemical, histological and molecular-biological assessments of gained samples (plasma, liver tissue, culture media and hepatocytes). Resveratrol and CAY attenuated APAP-induced hepatotoxicity in vivo and in vitro. Moreover, both drugs enhanced APAP-reduced SIRT1 activity. Our results show that modulation of the SIRT1 activity plays a role in hepatoprotection. Synthetic activators of SIRT1 would help in understanding the role of SIRT1 and are therefore a major boost towards the search for specific treatment of liver disease.

• MeSH
• hepatocyty účinky léků   metabolismus   MeSH
• krysa rodu Rattus MeSH
• kultivované buňky MeSH
• lékové postižení jater farmakoterapie   metabolismus   MeSH
• modely nemocí na zvířatech * MeSH
• paracetamol toxicita   MeSH
• potkani Wistar MeSH
• resveratrol MeSH
• sirtuin 1 fyziologie   MeSH
• stilbeny farmakologie   terapeutické užití   MeSH
• viabilita buněk účinky léků   fyziologie   MeSH
• zvířata MeSH
• Check Tag
• krysa rodu Rattus MeSH
• mužské pohlaví MeSH
• zvířata MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH
• Názvy látek
• paracetamol MeSH
• resveratrol MeSH
• sirtuin 1 MeSH
• stilbeny MeSH

Deficient sperm motility is a frequent cause of the age-related male sub-/infertility. Since the protein sirtuin 1 (SIRT1) develops anti-aging action and participates in sperm motility and ATP synthesis in mitochondria, we investigated its role in the acquisition of hyperactivated motility during capacitation. For this, the dynamics of sperm subpopulations were studied, using males of Sirt1+/- heterozygous mutant mice. After 2 hr of capacitation, we observed reduced percentage of hyperactivated spermatozoa in Sirt1+/- males. Interestingly, prior to capacitation, Sirt1+/- spermatozoa showed higher mitochondrial superoxide levels, which could render mitochondrial injury and thereby motility defects. Accordingly, the fertilization rate of Sirt1+/- males after mating was decreased. We elucidated that SIRT1 male insufficiency underlies posterior sperm defects to hyperactivate during capacitation and propose Sirt1+/- males as a model for the study of the age-related infertility.

• Klíčová slova
• SIRT1, hyperactivated motility, infertility, sperm capacitation,
• MeSH
• adenosintrifosfát metabolismus   MeSH
• fertilizace fyziologie   MeSH
• kapacitace spermií MeSH
• motilita spermií MeSH
• mužská infertilita * genetika   metabolismus   veterinární   MeSH
• myši MeSH
• sirtuin 1 genetika   metabolismus   MeSH
• sperma MeSH
• spermie fyziologie   MeSH
• superoxidy MeSH
• zvířata MeSH
• Check Tag
• mužské pohlaví MeSH
• myši MeSH
• zvířata MeSH
• Publikační typ
• časopisecké články MeSH
• Názvy látek
• adenosintrifosfát MeSH
• Sirt1 protein, mouse MeSH Prohlížeč
• sirtuin 1 MeSH
• superoxidy MeSH

Sirtuins, named after their homology to the Saccharomyces cerevisiae Silent Information Regulator Two, constitute a family of highly conserved nicotinamide adenine dinucleotide-dependent enzymes that deacetylate histones and residues of acetylated lysine. The main aim of this article is to put forward the pharmacological importance of major sirtuin 1 activators of natural or synthetic origin tested in last years in cases of oxidative tissue damage. The related bioactivity of these activators as "leading" compounds in the search for new drugs and remedies is also described. With the recent development of our knowledge on the cross talks between sirtuin 1 and its modulators (e.g. resveratrol), pharmacological and clinical research on this topic is getting a new horizon.

• MeSH
• antioxidancia farmakologie   fyziologie   MeSH
• lidé MeSH
• oxidační stres fyziologie   MeSH
• sirtuin 1 fyziologie   MeSH
• Check Tag
• lidé MeSH
• Publikační typ
• anglický abstrakt MeSH
• časopisecké články MeSH
• přehledy MeSH
• Názvy látek
• antioxidancia MeSH
• sirtuin 1 MeSH

AIM: Currently available medicines have little to offer in terms of supporting the regeneration of injured hepatic cells. Previous experimental studies have shown that resveratrol and metformin, less specific activators of AMP-activated protein kinase (AMPK) and sirtuin 1 (SIRT1), can effectively attenuate acute liver injury. The aim of this experimental study was to elucidate whether modulation of AMPK and SIRT1 activity can modify drug/paracetamol (APAP)-induced hepatocyte damage in vitro. METHODS: Primary rat hepatocytes were pretreated with mutual combinations of specific synthetic activators and inhibitors of SIRT1 and AMPK and followed by a toxic dose of APAP. At the end of cultivation, medium samples were collected for biochemical analysis of alanine-aminotransferase and nitrite levels. Hepatocyte viability, thiobarbituric reactive substances, SIRT1 and AMPK activity and protein expression were also assessed. RESULTS: The harmful effect of APAP was associated with decreased AMPK and SIRT1 activity and protein expression alongside enhanced oxidative stress in hepatocytes. The addition of AMPK activator (AICAR) or SIRT1 activator (CAY10591) significantly attenuated the deleterious effects of AMPK inhibitor (Compound C) on the hepatotoxicity of APAP. Furthermore, CAY10591 but not AICAR markedly decreased the deleterious effect of APAP in combination with SIRT1 inhibitor (EX-527). CONCLUSION: Our findings demonstrate that decreased AMPK activity is associated with the hepatotoxic effect of APAP which can be significantly attenuated by the administration of a SIRT1 activator. These findings suggest that differentiated modulation of AMPK and SIRT1 activity could therefore provide an interesting and novel therapeutic opportunity in the future to combat hepatocyte injury.

• Klíčová slova
• 5-aminoimidazole-4-carboxamide ribonucleotide (AICAR), CAY10591, adenosine monophosphate protein kinase (AMPK), enzyme activation, hepatocyte protection, sirtuin 1 (SIRT1),
• MeSH
• cyklopentany farmakologie   MeSH
• hepatocyty * metabolismus   MeSH
• krysa rodu Rattus MeSH
• lékové postižení jater * etiologie   genetika   metabolismus   patologie   MeSH
• paracetamol toxicita   MeSH
• proteinkinasy aktivované AMP * chemie   metabolismus   farmakologie   MeSH
• sirtuin 1 * metabolismus   farmakologie   MeSH
• zvířata MeSH
• Check Tag
• krysa rodu Rattus MeSH
• zvířata MeSH
• Publikační typ
• časopisecké články MeSH
• Názvy látek
• CAY10591 MeSH Prohlížeč
• cyklopentany MeSH
• paracetamol MeSH
• proteinkinasy aktivované AMP * MeSH
• Sirt1 protein, rat MeSH Prohlížeč
• sirtuin 1 * MeSH

This article is directed at highlighting the involvement of the endogenous stress sensor SIRT1 (silent information regulator T1) as a possible factor involved in hepatoprotection. The selective SIRT1 modulators whether activators (STACs) or inhibitors are being tried experimentally and clinically. We discuss the modulation of SIRT1 on cytoprotection or even cytotoxicity in the liver chemically injured by hepatotoxic agents in rats, to shed light on the crosstalk between SIRT1 and its modulators. A combination of D-galactosamine and lipopolysaccharide (D-GalN/LPS) downregulated SIRT1 expression, while SIRT1 activators, SRT1720, resveratrol, and quercetin, upregulated SIRT1 and alleviated D-GalN/LPS-induced acute hepatotoxicity. Liver injury markers exhibited an inverse relationship with SIRT1 expression. However, under subchronic hepatotoxicity, quercetin decreased the significant increase in SIRT1 expression to lower levels which are still higher than normal ones and mitigated the liver-damaging effects of carbon tetrachloride. Each of these STACs was hepatoprotective and returned the conventional antioxidant enzymes to the baseline. Polyphenols tend to fine-tune SIRT1 expression towards normal in the liver of intoxicated rats in both acute and subchronic studies. Together, all these events give an impression that the cytoprotective effects of SIRT1 are exhibited within a definite range of expression. The catalytic activity of SIRT1 is important in the hepatoprotective effects of polyphenols where SIRT1 inhibitors block and the allosteric SIRT1 activators mimic the hepatoprotective effects of polyphenols. Our findings indicate that the pharmacologic modulation of SIRT1 could represent both an important move in alleviating hepatic insults and a future major step in the treatment of xenobiotic-induced hepatotoxicity.

• MeSH
• lékové postižení jater farmakoterapie   enzymologie   MeSH
• lidé MeSH
• polyfenoly farmakologie   MeSH
• sirtuin 1 antagonisté a inhibitory   metabolismus   MeSH
• zvířata MeSH
• Check Tag
• lidé MeSH
• zvířata MeSH
• Publikační typ
• časopisecké články MeSH
• přehledy MeSH
• Názvy látek
• polyfenoly MeSH
• sirtuin 1 MeSH

The involvement of the mTOR system/enzyme sirtuin 1 (SIRT1) intracellular signaling system in the control of ovarian functions and its role in mediating hormonal action on the ovary has been proposed, but this hypothesis should be supported by a demonstrated influence of hormones on mTOR/SIRT1. Therefore, the aim of our in vitro experiments was to examine the effect of the known hormonal regulators of ovarian functions, such as follicle-stimulating hormone (FSH), oxytocin (OT) and insulin-like growth factor I (IGF-I), on mTOR/SIRT1. The accumulation of SIRT1 in porcine ovarian granulosa cells cultured with and without these hormones (at doses of 1, 10 or 100 ng.ml-1) was evaluated using immunocytochemistry. It was observed that the addition of FSH (at 10 ng.ml-1 but not at 1 or 100 ng/ml) and OT (at all tested doses) increased the expression of SIRT1 in ovarian cells. In addition, 100 ng.ml-1, but not at 1 or 10 ng.ml-1, of IGF-I decreased SIRT1 accumulation. Our observations are the first demonstration that hormones can directly regulate the ovarian mTOR/SIRT1 system and that this system could mediate the action of hormonal regulators on the ovary.

• MeSH
• apoptóza účinky léků   MeSH
• folikulární buňky cytologie   účinky léků   metabolismus   MeSH
• folikuly stimulující hormon farmakologie   MeSH
• insulinu podobný růstový faktor I farmakologie   MeSH
• kultivované buňky MeSH
• ovarium cytologie   účinky léků   metabolismus   MeSH
• oxytocin farmakologie   MeSH
• prasata MeSH
• proliferace buněk účinky léků   MeSH
• sirtuin 1 biosyntéza   genetika   metabolismus   MeSH
• uterotonika farmakologie   MeSH
• zvířata MeSH
• Check Tag
• ženské pohlaví MeSH
• zvířata MeSH
• Publikační typ
• časopisecké články MeSH
• Názvy látek
• folikuly stimulující hormon MeSH
• insulinu podobný růstový faktor I MeSH
• oxytocin MeSH
• sirtuin 1 MeSH
• uterotonika MeSH