To explore the effects and underlying mechanisms of Mdivi-1 on three common clinical models of acute kidney injury (AKI). Three common AKI cell models were constructed, classified into the control group (human renal tubular epithelial cells [HK-2] cells), the Iohexol group (HK-2 cells treated with Iohexol), the Genta group (HK-2 cells treated with Gentamicin), and the Cis group (HK-2 cells treated with Cisplatin). To explore the optimal protective concentration of Mdivi-1 for each AKI cell model, the experimental design consisted of the following seven groups: the control group (HK-2 cells cultured in medium), three injury groups (HK-2 cells subjected to Iohexol, Gentamicin, or Cisplatin), and the corresponding protection groups (with a certain concentration of Mdivi-1 added to each injury group). Cellular survival and apoptosis, reactive oxygen species (ROS) levels, and the expression of recombinant Sirtuin 3 (SIRT3) in each group were measured. Mitochondrial fission and fusion dynamics in cells were observed under an electron microscope. To explore relevant pathways, the changes in relevant pathway proteins were analyzed through Western blotting. The half maximal inhibitory concentration (IC50) values were 150.06 mgI/ml at 6 h in the Iohexol group, 37.88 mg/ml at 24 h in the Gentamicin group, and 13.48 microM at 24 h in the Cisplatin group. Compared with the control group, the three injury groups showed increased cell apoptosis rates and higher expressions of apoptotic proteins in HK-2 cells, with an accompanying decrease in cell migration. After the addition of corresponding concentrations of Mdivi-1, the optimal concentrations were 3 μM in the Iohexo-3 group, 1 microM in the Genta-1 group, and 5 μM in the Cis-5 group, HK-2 cells showed the highest survival rate, reduced apoptosis, decreased mitochondrial ROS and SIRT3 expression, and reduced mitochondrial fission and autophagy when compared with each injury group. Further verification with Western blot analysis after the addition of Mdivi-1 revealed a reduction in the expressions of mitochondrial fission proteins DRP1, Nrf2, SIRT3, Caspase-3, Jun N-terminal Kinase (JNK)/P-JNK, NF-kappaB, Bcl2, and autophagic protein P62, as well as reduced ROS levels. Mdivi-1 had protective effects on the three common AKI cell models by potentially reducing mitochondrial fission in cells and inhibiting the production of ROS through the mediation of the NF- B/JNK/SIRT3 signaling pathway, thereby exerting protective effects. Key words AKI, Cisplatin, Gentamicin, Iohexol, Mdivi-1.
- MeSH
- akutní poškození ledvin * metabolismus patologie farmakoterapie MeSH
- apoptóza účinky léků MeSH
- buněčné linie MeSH
- lidé MeSH
- MAP kinasový signální systém účinky léků fyziologie MeSH
- mitochondriální dynamika * účinky léků fyziologie MeSH
- NF-kappa B * metabolismus MeSH
- reaktivní formy kyslíku metabolismus MeSH
- signální transdukce * účinky léků MeSH
- sirtuin 3 * metabolismus MeSH
- Check Tag
- lidé MeSH
- Publikační typ
- časopisecké články MeSH
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.
Pulmonary hypertension (PH) is a heterogeneous and life-threatening cardiopulmonary disorder in which mitochondrial dysfunction is believed to drive pathogenesis, although the underlying mechanisms remain unclear. To determine if abnormal SIRT3 (sirtuin 3) activity is related to mitochondrial dysfunction in adventitial fibroblasts from patients with idiopathic pulmonary arterial hypertension (IPAH) and hypoxic PH calves (PH-Fibs) and whether SIRT3 could be a potential therapeutic target to improve mitochondrial function, SIRT3 concentrations in control fibroblasts, PH-Fibs, and lung tissues were determined using quantitative real-time PCR and western blot. SIRT3 deacetylase activity in cells and lung tissues was determined using western blot, immunohistochemistry staining, and immunoprecipitation. Glycolysis and mitochondrial function in fibroblasts were measured using respiratory analysis and fluorescence-lifetime imaging microscopy. The effects of restoring SIRT3 activity (by overexpression of SIRT3 with plasmid, activation SIRT3 with honokiol, and supplementation with the SIRT3 cofactor nicotinamide adenine dinucleotide [NAD+]) on mitochondrial protein acetylation, mitochondrial function, cell proliferation, and gene expression in PH-Fibs were also investigated. We found that SIRT3 concentrations were decreased in PH-Fibs and PH lung tissues, and its cofactor, NAD+, was also decreased in PH-Fibs. Increased acetylation in overall mitochondrial proteins and SIRT3-specific targets (MPC1 [mitochondrial pyruvate carrier 1] and MnSOD2 [mitochondrial superoxide dismutase]), as well as decreased MnSOD2 activity, was identified in PH-Fibs and PH lung tissues. Normalization of SIRT3 activity, by increasing its expression with plasmid or with honokiol and supplementation with its cofactor NAD+, reduced mitochondrial protein acetylation, improved mitochondrial function, inhibited proliferation, and induced apoptosis in PH-Fibs. Thus, our study demonstrated that restoration of SIRT3 activity in PH-Fibs can reduce mitochondrial protein acetylation and restore mitochondrial function and PH-Fib phenotype in PH.
- MeSH
- fibroblasty metabolismus MeSH
- lidé MeSH
- mitochondriální proteiny metabolismus MeSH
- mitochondrie metabolismus MeSH
- NAD metabolismus MeSH
- plicní hypertenze * patologie MeSH
- sirtuin 3 * genetika metabolismus MeSH
- skot MeSH
- zvířata MeSH
- Check Tag
- lidé MeSH
- skot MeSH
- zvířata MeSH
- Publikační typ
- časopisecké články MeSH
- práce podpořená grantem MeSH
- Research Support, N.I.H., Extramural MeSH
- Research Support, U.S. Gov't, Non-P.H.S. MeSH
BACKGROUND: The study was undertaken to evaluate the effect of 6-week supplementation with a daily dose of 2g of curcumin on VO2max and prooxidant/antioxidant homeostasis in middle-aged amateur long-distance runners during the preparatory period of the macrocycle. METHODS: Thirty runners were randomly assigned to a placebo group (PL) and a curcumin-supplemented group (CU). Their VO2max was assessed before supplementation and after 6 weeks of supplementation. Venous blood samples were collected from the participants at rest, immediately after exercise, and after 1h of recovery to evaluate the activity of antioxidant enzymes (SOD, CAT, GPx), non-enzymatic antioxidants (GSH, UA) and sirtuin 3 level (SIRT 3), as well as the levels of oxidative stress markers (TOS/TOC, MDA, and 8-OHdG) and muscle damage markers (CK, LDH, and Mb). RESULTS: VO2max, the activity of enzymatic antioxidants, the concentrations of non-enzymatic antioxidants, the levels of oxidative stress markers, and the levels of muscle damage markers did not change significantly in the CU group over 6 weeks of supplementation with curcumin. However, the resting concentration of SIRT 3 was found to be significantly higher (p ≤ 0.05) compared with pre-supplementation. CONCLUSION: Curcumin supplementation does not have a significant effect on VO2max and prooxidant/antioxidant homeostasis in runners.
- MeSH
- antioxidancia MeSH
- kurkumin * MeSH
- lidé MeSH
- měď MeSH
- potravní doplňky MeSH
- reaktivní formy kyslíku MeSH
- sirtuin 3 * MeSH
- superoxiddismutasa MeSH
- Check Tag
- lidé MeSH
- Publikační typ
- časopisecké články MeSH
- randomizované kontrolované studie MeSH
Wild type mitochondrial isocitrate dehydrogenase (IDH2) was previously reported to produce oncometabolite 2-hydroxyglutarate (2HG). Besides, mitochondrial deacetylase SIRT3 has been shown to regulate the oxidative function of IDH2. However, regulation of 2HG formation by SIRT3-mediated deacetylation was not investigated yet. We aimed to study mitochondrial IDH2 function in response to acetylation and deacetylation, and focus specifically on 2HG production by IDH2. We used acetylation surrogate mutant of IDH2 K413Q and assayed enzyme kinetics of oxidative decarboxylation of isocitrate, 2HG production by the enzyme, and 2HG production in cells. The purified IDH2 K413Q exhibited lower oxidative reaction rates than IDH2 WT. 2HG production by IDH2 K413Q was largely diminished at the enzymatic and cellular level, and knockdown of SIRT3 also inhibited 2HG production by IDH2. Contrary, the expression of putative mitochondrial acetylase GCN5L likely does not target IDH2. Using mass spectroscopy, we further identified lysine residues within IDH2, which are the substrates of SIRT3. In summary, we demonstrate that 2HG levels arise from non-mutant IDH2 reductive function and decrease with increasing acetylation level. The newly identified lysine residues might apply in regulation of IDH2 function in response to metabolic perturbations occurring in cancer cells, such as glucose-free conditions.
- MeSH
- acetylace MeSH
- glutaráty metabolismus MeSH
- isocitrátdehydrogenasa genetika metabolismus MeSH
- isocitráty chemie MeSH
- lidé MeSH
- mitochondrie metabolismus MeSH
- nádorové buněčné linie MeSH
- NADP metabolismus MeSH
- oxidace-redukce MeSH
- proteiny nervové tkáně metabolismus MeSH
- sirtuin 3 metabolismus MeSH
- umlčování genů MeSH
- Check Tag
- lidé MeSH
- Publikační typ
- časopisecké články MeSH
- práce podpořená grantem MeSH
