scholarly journals mTORC2 is the Primary Target for Simvastatin-Associated Toxicity in C2C12 Cells and in Mouse Skeletal Muscle

2021 ◽  
Author(s):  
Gerda M Sanvee ◽  
Leonie Hitzfeld ◽  
Jamal Bouitbir ◽  
Stephan Krahenbuhl
Keyword(s):  
Ldl Cholesterol ◽  
Complex Iii ◽  
C2c12 Cells ◽  
Cholesterol Concentration ◽  
Antimycin A ◽  
Primary Target ◽  
C2c12 Myoblasts ◽  
Knock Down ◽  
Mitochondrial Superoxide ◽  
And Function

Abstract Statins decrease the serum LDL-cholesterol concentration and reduce the risk for cardiovascular diseases but can cause myopathy, which may be related to mTORC inhibition. In the current study, we investigated which mTORC is inhibited by simvastatin and by which mechanisms. In C2C12 myoblasts and myotubes and mouse gastrocnemius, simvastatin was cytotoxic and inhibited S6rp and Akt Ser473 phosphorylation, indicating inhibition of mTORC1 and mTORC2, respectively. In contrast to simvastatin, the mTORC1 inhibitor rapamycin did not inhibit mTORC2 and was not cytotoxic. Like simvastatin, knock-down of Rictor, an essential component of mTORC2, impaired Akt Ser473 and S6rp phosphorylation and was cytotoxic for C2C12 myoblasts, suggesting that mTORC2 inhibition is an important myotoxic mechanism. The investigation of the mechanism of mTORC2 inhibition showed that simvastatin impaired Ras farnesylation, which was prevented by farnesol but without restoring mTORC2 activity. In comparison, Rap1 knock-down reduced mTORC2 activity and was cytotoxic for C2C12 myoblasts. Simvastatin impaired Rap1 prenylation and function, which was prevented by geranylgeraniol. In addition, simvastatin and the complex III inhibitor antimycin A caused mitochondrial superoxide accumulation and decreased the activity of mTORC2, which could partially be prevented by the antioxidant MitoTEMPO. In conclusion, mTORC2 inhibition is an important mechanism of simvastatin-induced myotoxicity. Simvastatin inhibits mTORC2 by impairing geranylgeranylation of Rap1 and by inducing mitochondrial dysfunction.

scholarly journals Antimycin A-Induced Mitochondrial Damage Causes Human RPE Cell Death despite Activation of Autophagy

2019 ◽  
Vol 2019 ◽  
pp. 1-12 ◽  
Author(s):  
Maria Hytti ◽  
Eveliina Korhonen ◽  
Juha M. T. Hyttinen ◽  
Heidi Roehrich ◽  
Kai Kaarniranta ◽  
...  
Keyword(s):  
Cell Death ◽  
Mitochondrial Dysfunction ◽  
Pigment Epithelium ◽  
Retinal Pigment ◽  
Mitochondrial Damage ◽  
Age Related Macular Degeneration ◽  
Complex Iii ◽  
Antimycin A ◽  
Age Related ◽  
And Function

Mitochondrial dysfunction has been implicated in a wide variety of degenerative diseases, including age-related macular degeneration. Damage to mitochondria and mitochondrial DNA accumulates with age in the postmitotic retinal pigment epithelium (RPE), which could lead to RPE cell death and trigger disease. One possible mechanism for cells to avoid cell death is mitophagy, the targeted clearance of damaged mitochondria by autophagy. Here, we induced mitochondrial damage in human RPE cells (ARPE-19 and hRPE), using antimycin A, an inhibitor of complex III of the electron transport chain, and investigated cellular viability, mitochondrial structure and function, and autophagy activity. We observed that antimycin A evoked dose-dependent cell death, a rapid loss in mitochondrial membrane potential, and a collapse of oxidative phosphorylation. Mitochondria appeared swollen and there was clear damage to their cristae structure. At the same time, cells were undergoing active autophagy and were sensitive to autophagy inhibition by bafilomycin A1 or chloroquine. These results indicate that mitochondrial dysfunction can cause significant RPE damage and that autophagy is an important survival mechanism for cells suffering from mitochondrial damage.

scholarly journals Metallothionein 3 Promotes Osteoblast Differentiation in C2C12 Cells via Reduction of Oxidative Stress

2021 ◽  
Vol 22 (9) ◽  
pp. 4312
Author(s):  
Santie Li ◽  
Myeong-Ji Kim ◽  
Sung-Ho Lee ◽  
Litai Jin ◽  
Weitao Cong ◽  
...  
Keyword(s):  
Osteoblast Differentiation ◽  
Redox Balance ◽  
C2c12 Cells ◽  
Antimycin A ◽  
Ros Production ◽  
Oxygen Species ◽  
C2c12 Myoblasts ◽  
Morphogenetic Protein ◽  
Living Organisms

Metallothioneins (MTs) are intracellular cysteine-rich proteins, and their expressions are enhanced under stress conditions. MTs are recognized as having the ability to regulate redox balance in living organisms; however, their role in regulating osteoblast differentiation is still unclear. In this research, we found that the expression of MT3, one member of the MT protein family, was specifically upregulated in the differentiation process of C2C12 myoblasts treated with bone morphogenetic protein 4 (BMP4). Transfection with MT3-overexpressing plasmids in C2C12 cells enhanced their differentiation to osteoblasts, together with upregulating the protein expression of bone specific transcription factors runt-related gene 2 (Runx2), Osterix, and distal-less homeobox 5 (Dlx5). Additionally, MT3 knockdown performed the opposite. Further studies revealed that overexpression of MT3 decreased reactive oxygen species (ROS) production in C2C12 cells treated with BMP4, and MT3 silencing enhanced ROS production. Treating C2C12 cells with antioxidant N-acetylcysteine also promoted osteoblast differentiation, and upregulated Runx2/Osterix/Dlx5, while ROS generator antimycin A treatment performed the opposite. Finally, antimycin A treatment inhibited osteoblast differentiation and Runx2/Osterix/Dlx5 expression in MT3-overexpressing C2C12 cells. These findings identify the role of MT3 in osteoblast differentiation and indicate that MT3 may have interesting potential in the field of osteogenesis research.

scholarly journals MicroRNA-199a Targets the Fatty Acid Transport Protein 1 Gene and Inhibits the Adipogenic Trans-Differentiation of C2C12 Myoblasts

2016 ◽  
Vol 39 (3) ◽  
pp. 1087-1097 ◽  
Author(s):  
Renli Qi ◽  
Dingbiao Long ◽  
Jing Wang ◽  
Qi Wang ◽  
Xiaofeng Huang ◽  
...  
Keyword(s):  
Fatty Acid ◽  
Muscle Cells ◽  
Transport Protein ◽  
C2c12 Cells ◽  
Fatty Acid Transport ◽  
Acid Transport ◽  
C2c12 Myoblasts ◽  
Fatty Acid Transport Protein ◽  
Over Expression ◽  
Knock Down

Background/Aims: Muscle cells are able to trans-differentiate into adipocytes with adipogenesis induction. MicroRNAs (miRNAs), a class of small non-coding RNAs, widely participate in the regulation of growth and development of cells. However, the expression and regulatory role of miRNAs in the trans-differentiation of muscle cell are largely unknown. Methods: C2C12 myoblasts were inducted to adipogenesis trans-differentiation and microarrays were used to assay the changes of expression profile of miRNAs. MiR-199a, a miRNA showed significant change in the trans-differentiation, was selected for the subsequent function study via over- expression and knock down. Results: Dozens of miRNAs showed different changes followed the adipogenesis trans-differentiation of C2C12 cells. In which, miR-199a was decreased in the adipogenic cells and miR-199a over-expression inhibited the trans-differentiation and decreased lipid accumulation in the cells. Moreover, Fatty acid transport protein 1 (Fatp1), a major regulator of trans-membrane transportation and the oxidative metabolism of free fatty acids, was showed to be a target of miR-199a by computational and luciferase reporter assays. Additionally, Fatp1 knock-down by small interfering RNA had similar inhibitory effects on the trans-differentiation in C2C12 cells. Conclusion: Our study reveals an important role for miR-199a in the regulation of adipogenic trans-differentiation in muscle cells via suppression of Fatp1 gene.

scholarly journals Creatine Prevents the Structural and Functional Damage to Mitochondria in Myogenic, Oxidatively Stressed C2C12 Cells and Restores Their Differentiation Capacity

2016 ◽  
Vol 2016 ◽  
pp. 1-12 ◽  
Author(s):  
Elena Barbieri ◽  
Michele Guescini ◽  
Cinzia Calcabrini ◽  
Luciana Vallorani ◽  
Anna Rita Diaz ◽  
...  
Keyword(s):  
Oxidative Stress ◽  
Antioxidant Activity ◽  
Nutritional Supplement ◽  
C2c12 Cells ◽  
Protective Effects ◽  
C2c12 Myoblasts ◽  
Beneficial Effects ◽  
Downstream Effector ◽  
Energy Sensor ◽  
And Function

Creatine (Cr) is a nutritional supplement promoting a number of health benefits. Indeed Cr has been shown to be beneficial in disease-induced muscle atrophy, improve rehabilitation, and afford mild antioxidant activity. The beneficial effects are likely to derive from pleiotropic interactions. In accord with this notion, we previously demonstrated that multiple pleiotropic effects, including preservation of mitochondrial damage, account for the capacity of Cr to prevent the differentiation arrest caused by oxidative stress in C2C12 myoblasts. Given the importance of mitochondria in supporting the myogenic process, here we further explored the protective effects of Cr on the structure, function, and networking of these organelles in C2C12 cells differentiating under oxidative stressing conditions; the effects on the energy sensor AMPK, onPGC-1α, which is involved in mitochondrial biogenesis and its downstream effectorTfamwere also investigated. Our results indicate that damage to mitochondria is crucial in the differentiation imbalance caused by oxidative stress and that the Cr-prevention of these injuries is invariably associated with the recovery of the normal myogenic capacity. We also found that Cr activates AMPK and induces an upregulation ofPGC-1αexpression, two events which are likely to contribute to the protection of mitochondrial quality and function.

Platelet Aggregation and Plasma Lipoproteins in Alcoholics During Alcohol Withdrawal

1986 ◽  
Vol 55 (02) ◽  
pp. 173-177 ◽  
Author(s):  
K Desai ◽  
J S Owen ◽  
D T Wilson ◽  
R A Hutton
Keyword(s):  
Platelet Aggregation ◽  
Alcohol Withdrawal ◽  
Ldl Cholesterol ◽  
Low Density Lipoprotein ◽  
Density Lipoprotein ◽  
Hdl Cholesterol ◽  
Plasma Lipoprotein ◽  
Cholesterol Concentration ◽  
Arachidonic Acid Content ◽  
Low Density

SummaryPlatelet aggregation, platelet lipid composition and plasma lipoprotein concentrations were measured each week in a group of seventeen alcoholics, without overt liver disease, for one month, following acute, total alcohol withdrawal. The platelets were initially hypoaggregable but, within 1-2 weeks of cessation of drinking, they became hyperaggregable and then gradually returned towards normal values. Hyperaggregability could not be explained by increases in either the cholesterol or the arachidonic acid content of the platelets. Plasma very-low-density lipoprotein cholesterol levels remained high throughout the study, but the initially raised levels of high-density lipoprotein (HDL) cholesterol fell by 26%. Low-density lipoprotein (LDL) cholesterol concentration rose by 10% after two weeks of withdrawal but then returned to about the starting level. The resulting changes in the plasma LDL-cholesterol: HDL-cholesterol ratio, which had increased by more than 50% after two weeks of abstinence, essentially paralleled the time course of enhanced platelet reactivity in all but four of the alcoholics. These findings suggest that alterations in plasma lipoprotein concentrations during acute alcohol withdrawal may be a contributory factor to the haemostatic disorders present in such patients.

NFATc3 regulates the transcription of genes involved in T-cell activation and angiogenesis

Blood ◽  
2011 ◽  
Vol 118 (3) ◽  
pp. 795-803 ◽  
Author(s):  
Katia Urso ◽  
Arantzazu Alfranca ◽  
Sara Martínez-Martínez ◽  
Amelia Escolano ◽  
Inmaculada Ortega ◽  
...  
Keyword(s):  
T Cells ◽  
T Cell ◽  
T Cell Activation ◽  
Cell Activation ◽  
Target Genes ◽  
Gene Knockout ◽  
Activated T Cells ◽  
Knock Down ◽  
And Function

Abstract The nuclear factor of activated T cells (NFAT) family of transcription factors plays important roles in many biologic processes, including the development and function of the immune and vascular systems. Cells usually express more than one NFAT member, raising the question of whether NFATs play overlapping roles or if each member has selective functions. Using mRNA knock-down, we show that NFATc3 is specifically required for IL2 and cyclooxygenase-2 (COX2) gene expression in transformed and primary T cells and for T-cell proliferation. We also show that NFATc3 regulates COX2 in endothelial cells, where it is required for COX2, dependent migration and angiogenesis in vivo. These results indicate that individual NFAT members mediate specific functions through the differential regulation of the transcription of target genes. These effects, observed on short-term suppression by mRNA knock-down, are likely to have been masked by compensatory effects in gene-knockout studies.

scholarly journals The role of sex steroids in the regulation of insulin sensitivity and serum lipid concentrations during male puberty: a prospective study with a P450-aromatase inhibitor

2002 ◽  
pp. 339-346 ◽  
Author(s):  
S Wickman ◽  
T Saukkonen ◽  
L Dunkel
Keyword(s):  
Insulin Sensitivity ◽  
Aromatase Inhibitor ◽  
Sex Steroids ◽  
Ldl Cholesterol ◽  
Density Lipoprotein ◽  
Treated Group ◽  
Lipoprotein Cholesterol ◽  
Cholesterol Concentration ◽  
Igf I ◽  
Letrozole Treatment

OBJECTIVE: Our purpose was to study the sex steroid-mediated changes in serum insulin and lipid concentrations in boys during puberty. DESIGN AND METHODS: We treated boys with constitutional delay of puberty either with testosterone plus placebo or with testosterone plus an aromatase inhibitor, letrozole, which inhibits the conversion of androgens to oestrogens. We demonstrated previously that during treatment with testosterone plus letrozole the increase in testosterone concentration was more than 5-fold higher than during treatment with testosterone plus placebo. The concentrations of 17beta-oestradiol, IGF-I and IGF-binding protein-3 increased during testosterone-plus-placebo treatment, but during testosterone-plus-letrozole treatment the concentrations remained unchanged. These divergent changes in the two groups enabled us to study the effects of sex steroids and GH on insulin sensitivity and lipid concentrations. RESULTS: The insulin concentration in the testosterone-plus-placebo-treated group did not change. In contrast, in the testosterone-plus-letrozole-treated group, the concentration decreased during letrozole treatment, indicating improved insulin sensitivity. Changes in insulin and IGF-I concentrations within 12 and 18 months were correlated. In the testosterone-plus-placebo-treated group, the high-density lipoprotein cholesterol concentration did not change but in the testosterone-plus-letrozole-treated group the concentration decreased. The concentrations of low-density lipoprotein cholesterol (LDL-cholesterol) and triglycerides did not change in either of the groups. CONCLUSIONS: The findings indicate that androgens do not directly alter insulin sensitivity in boys during puberty. In contrast, the observations suggest tight regulation of glucose--insulin homeostasis by GH in boys at this stage. Furthermore, our findings indicate that sex steroids do not significantly participate in the regulation of serum concentrations of LDL-cholesterol or triglycerides in boys during early and mid-puberty.

Abstract 3: Il-10 Regulated Mir-375 Enhances Endothelial Progenitor Cell Mediated Myocardial Repair And Survival After Myocardial Infarction.

2014 ◽  
Vol 115 (suppl_1) ◽  
Author(s):  
Venkata N Garikipati ◽  
Prasanna Krishnamurthy ◽  
Suresh K Verma ◽  
Alexandra R Mackie ◽  
Erin E Vaughan ◽  
...  
Keyword(s):  
Capillary Density ◽  
Tube Formation ◽  
Lv Function ◽  
Myocardial Repair ◽  
Knock Down ◽  
Cardiac Functions ◽  
Dependent Protein ◽  
And Function ◽  
Deficient Mice

We hypothesized that IL-10 regulates miR-375 signaling in EPCs to enhance their survival and function in ischemic myocardium after MI. miR-375 knock down EPC were transplanted intramyocardially after induction of MI. Mice receiving EPC treated with miR-375 inhibitor showed increased number of GFP+EPCs retention that was associated with reduced EPC apoptosis in the myocardium. The engraftment of EPC into the vascular structures and the associated capillary density was significantly higher in miR-375-treated mice. The above findings further correlated with reduced infarct size, fibrosis and enhanced LV function (echocardiography) in miR-375 knock down EPC group as compared to scrambled EPC. Our in vitro studies revealed that the knockdown of miR-375 enhanced EPC proliferation, migration; tube formation ability and inhibited cell apoptosis, while the up-regulation of miR-375 with the mimic had the opposite effects. In addition, we found that miR-375 negatively regulates the expression of 3-phosphoinositide-dependent protein kinase 1 (PDK1) by directly targeting the 3'UTR of the PDK1 transcript. Interestingly, EPC isolated from IL-10-deficient mice has elevated basal levels of miR-375 and exhibited poor proliferation and tube formation ability where as miR-375 knock down in EPC isolated from IL-10 deficient mice attenuated these effects. Furthermore, transplantation of miR-375 knock down IL-10 deficient EPC after MI resulted in attenuated cardiac functions compared to scramble IL-10 deficient EPCs. Taken together, our studies suggest that IL-10 regulated miR-375 enhances EPC survival and function, associated with efficient myocardial repair via activation of PDK-1/AKT signaling cascades.

Interleukin-6 promotes myogenic differentiation of mouse skeletal muscle cells: role of the STAT3 pathway

2013 ◽  
Vol 304 (2) ◽  
pp. C128-C136 ◽  
Author(s):  
Miriam Hoene ◽  
Heike Runge ◽  
Hans Ulrich Häring ◽  
Erwin D. Schleicher ◽  
Cora Weigert
Keyword(s):  
Skeletal Muscle ◽  
Mrna Expression ◽  
Myogenic Differentiation ◽  
Muscle Cells ◽  
C2c12 Cells ◽  
Skeletal Muscle Cells ◽  
Wild Type ◽  
C2c12 Myoblasts ◽  
Sequence Of Events ◽  
Primary Mouse

Myogenic differentiation of skeletal muscle cells is characterized by a sequence of events that include activation of signal transducer and activator of transcription 3 (STAT3) and enhanced expression of its target gene Socs3. Autocrine effects of IL-6 may contribute to the activation of the STAT3-Socs3 cascade and thus to myogenic differentiation. The importance of IL-6 and STAT3 for the differentiation process was studied in C2C12 cells and in primary mouse wild-type and IL-6−/− skeletal muscle cells. In differentiating C2C12 myoblasts, the upregulation of IL-6 mRNA expression and protein secretion started after increased phosphorylation of STAT3 on tyrosine 705 and increased mRNA expression of Socs3 was observed. Knockdown of STAT3 and IL-6 mRNA in differentiating C2C12 myoblasts impaired the expression of the myogenic markers myogenin and MyHC IIb and subsequently myotube fusion. However, the knockdown of IL-6 did not prevent the induction of STAT3 tyrosine phosphorylation. The IL-6-independent activation of STAT3 was verified in differentiating primary IL-6−/− myoblasts. The phosphorylation of STAT3 and the expression levels of STAT3, Socs3, and myogenin during differentiation were comparable in the primary myoblasts independent of the genotype. However, IL-6−/− cells failed to induce MyHC IIb expression to the same level as in wild-type cells and showed reduced myotube formation. Supplementation of IL-6 could partially restore the fusion of IL-6−/− cells. These data demonstrate that IL-6 depletion during myogenic differentiation does not reduce the activation of the STAT3-Socs3 cascade, while IL-6 and STAT3 are both necessary to promote myotube fusion.

scholarly journals THE CLINICAL SIGNIFICANCE OF THE DAILY MONITORING OF HOLTER ECG IN CHRONIC GLOMERULONEPHRITIS AT THE PREDIALYSIS STAGE OF THE DISEASE

2019 ◽  
Vol 9 (1) ◽  
pp. 44-51
Author(s):  
I. T. Murkamilov ◽  
I. S. Sabirov ◽  
V. V. Fomin ◽  
Zh. A. Murkamilova ◽  
A. I. Sabirova ◽  
...  
Keyword(s):  
Heart Rate ◽  
Ldl Cholesterol ◽  
Clinical Importance ◽  
Holter Monitoring ◽  
Cardiovascular Complications ◽  
Cholesterol Concentration ◽  
Chronic Glomerulonephritis ◽  
Daily Monitoring ◽  
Daily Excretion ◽  
Laboratory Examinations

This article presents the results of our own research: comprehensive clinical and laboratory examinations, including data from the daily Holter monitoring of the electrocardiogram (DMEKG) in 169 patients with chronic glomerulonephritis at the predialysis stage of the disease. According to the DMEKG, 60.3% of the persons examined by us had episodes of supraventricular group extrasystoles, and ventricular group extrasystoles in 28.9%. In addition, 11.2% of patients had atrial ventricular blockade (incomplete / partial), 8.8% had atrial fibrillation and painless ischemia in an amount of from 1 to 3 episodes per day in 14.7%. Depending on the average heart rate (HR) according to the DMEKG, patients with chronic glomerulonephritis were divided into two subgroups. Subgroup “A” included 38 patients with heart rate less than or equal to 70 beats / min, in subgroup “B” — 131 patients with a heart rate of more than 70 beats / min. With equal values of uric acid, total cholesterol cholesterol, HDL cholesterolcholesterol, TG, plasma creatinine and blood fibrinogen in subgroup “B” there was a statistically significant increase in LDL cholesterol concentration(3.58 (2.74; 5.54) mmol / l vs. 2, 82 (2.30; 3.86) mmol / l; p <0.05) and a decrease in the calculated GFR (70.4 (48.8; 96.3) ml / min vs. 85.7 (31.5; 103,1) ml / min; p <0.05) compared with subgroup “A”. In the subgroup “B” a tendency was observed to increase the degree of daily excretion of protein with urine. The data obtained confirm the fact that the conduct of the DMEKG with the analysis of heart rate is of significant clinical importance for the diagnosis of cardiovascular disorders and the p revention of cardiovascular complications in chronic glomerulonephritis at the predialysis stage of the disease.

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