scholarly journals Silencing of PARP2 Blocks Autophagic Degradation

Cells ◽  
2020 ◽  
Vol 9 (2) ◽  
pp. 380 ◽  
Author(s):  
Laura Jankó ◽  
Zsanett Sári ◽  
Tünde Kovács ◽  
Gréta Kis ◽  
Magdolna Szántó ◽  
...  
Keyword(s):  
Mammalian Target Of Rapamycin ◽  
C2c12 Cells ◽  
Myoblast Differentiation ◽  
Serum Starvation ◽  
Autophagic Flux ◽  
Embryonic Fibroblasts ◽  
Nicotinamide Riboside ◽  
Chloroquine Treatment ◽  
Autophagic Degradation ◽  
Sirt1 Inhibitor

Poly(ADP-Ribose) polymerases (PARPs) are enzymes that metabolize NAD+. PARP1 and PARP10 were previously implicated in the regulation of autophagy. Here we showed that cytosolic electron-dense particles appear in the cytoplasm of C2C12 myoblasts in which PARP2 is silenced by shRNA. The cytosolic electron-dense bodies resemble autophagic vesicles and, in line with that, we observed an increased number of LC3-positive and Lysotracker-stained vesicles. Silencing of PARP2 did not influence the maximal number of LC3-positive vesicles seen upon chloroquine treatment or serum starvation, suggesting that the absence of PARP2 inhibits autophagic breakdown. Silencing of PARP2 inhibited the activity of AMP-activated kinase (AMPK) and the mammalian target of rapamycin complex 2 (mTORC2). Treatment of PARP2-silenced C2C12 cells with AICAR, an AMPK activator, nicotinamide-riboside (an NAD+ precursor), or EX-527 (a SIRT1 inhibitor) decreased the number of LC3-positive vesicles cells to similar levels as in control (scPARP2) cells, suggesting that these pathways inhibit autophagic flux upon PARP2 silencing. We observed a similar increase in the number of LC3 vesicles in primary PARP2 knockout murine embryonic fibroblasts. We provided evidence that the enzymatic activity of PARP2 is important in regulating autophagy. Finally, we showed that the silencing of PARP2 induces myoblast differentiation. Taken together, PARP2 is a positive regulator of autophagic breakdown in mammalian transformed cells and its absence blocks the progression of autophagy.

scholarly journals Facilitated Ca2+ homeostasis and attenuated myocardial autophagy contribute to alleviation of diabetic cardiomyopathy after bariatric surgery

2018 ◽  
Vol 315 (5) ◽  
pp. H1258-H1268 ◽  
Author(s):  
Xin Huang ◽  
Shaozhuang Liu ◽  
Dong Wu ◽  
Yugang Cheng ◽  
Haifeng Han ◽  
...  
Keyword(s):  
Bariatric Surgery ◽  
Diabetic Cardiomyopathy ◽  
Ventricular Myocytes ◽  
Mammalian Target Of Rapamycin ◽  
Diabetic Rats ◽  
Diabetic Rat ◽  
Autophagic Flux ◽  
Fk506 Binding Protein ◽  
Plasmic Reticulum ◽  
Chloroquine Treatment

Bariatric surgery has been reported to relieve diabetic cardiomyopathy (DCM) effectively. However, the mechanisms remain largely unknown. To determine the effects of bariatric surgery on DCM via modulation of myocardial Ca2+ homeostasis and autophagy, sleeve gastrectomy (SG), duodenal-jejunal bypass (DJB), and sham surgeries were performed in diabetic rats induced by high-fat diet and a low dose of streptozotocin. Cardiac remodeling was assessed by a series of morphometric and histological analyses. Transthoracic echocardiography and hemodynamic measurements were performed to determine cardiac function. Ca2+ homeostasis was evaluated by measuring Ca2+ transients with fura-2 AM in isolated ventricular myocytes along with detection of the abundance of Ca2+ regulatory proteins in the myocardium. Myocardial autophagic flux was determined by expression of autophagy-related proteins in the absence and presence of chloroquine. Both SG and DJB surgery alleviated DCM morphologically and functionally. Ca2+ transients exhibited a significantly higher amplitude and faster decay after SG and DJB, which could be partially explained by increased expression of ryanodine receptor 2, sarco(endo)plasmic reticulum Ca2+-2ATPase, 12.6-kDa FK506-binding protein, and hyperphosphorylation of phospholamban. In addition, a lower level of light chain 3B and higher level of p62 were detected after both SG and DJB, which was not reversed by chloroquine treatment and associated with activated mammalian target of rapamycin and attenuated AMP-activated protein kinase signaling pathway. Collectively, these results provided evidence that bariatric surgery could alleviate DCM effectively, which may result, at least in part, from facilitated Ca2+ homeostasis and attenuated autophagy, suggesting a potential choice for treatment of DCM when properly implemented. NEW & NOTEWORTHY The present study is the first to investigate the modulation of myocardial Ca2+ homeostasis and autophagy after bariatric surgery and to examine its effects on diabetic cardiomyopathy. Bariatric surgery could facilitate myocardial Ca2+ homeostasis and attenuate myocardial autophagy, contributing to the alleviation of cardiomyopathy morphologically and functionally in a diabetic rat model.

The Polyphenolic Compound Curcumin Conjugation with an Alkyne Moiety in the Process of Autophagy

2018 ◽  
Vol 46 (03) ◽  
pp. 673-687 ◽  
Author(s):  
Peiyi Yan ◽  
Xin Sun ◽  
Xiaochen Chen ◽  
Yun Chen ◽  
Xiao Wang ◽  
...  
Keyword(s):  
Therapeutic Agent ◽  
Mammalian Target Of Rapamycin ◽  
Autophagic Flux ◽  
Cell Growth Inhibition ◽  
Polyphenolic Compound ◽  
Mouse Embryonic Fibroblasts ◽  
Curcumin Treatment ◽  
Embryonic Fibroblasts ◽  
Evolutionarily Conserved ◽  
Related Proteins

Curcumin is a hydrophobic polyphenol derived from turmeric: the rhizome of the herb Curcumalonga. Autophagy is an evolutionarily conserved process, in which cellular proteins and organelles are engulfed in autophagosome and then fuses with lysosome for degradation. Our previous study showed that Curcumin activates lysosome and induce autophagy through inhibition of AKT (protein kinase K, PKB)-mammalian target of rapamycin (mTOR) pathway. But whether Curucmin affects the fusion of autophagosome-lysosome is still not clear. Here, we used Curcumin-probe conjugation with an alkyne moiety to label mouse embryonic fibroblasts (MEFs) and found that Curcumin targets autophagy-related proteins, enhances autophagic flux and activates lysosome in cells. Moreover, Curcumin treatment promotes the fusion of autophasosome-lysosome in MEFs. Second, the enhanced fusion of autophagosome-lysosome is attributed to mTOR suppression. Third, blockage of the autophagosome-lysosome fusion leads to cell growth inhibition by Curcumin. Taken together, data from our study indicates the importance of the fusion of autophagosome-lysosome in Curcumin-induced autophagy, which may facilitate the development of Curcumin as a potential therapeutic agent for oxidative stress-related diseases.

scholarly journals CREB-mediated transcriptional activation of NRMT1 drives muscle differentiation

2021 ◽  
Author(s):  
John G Tooley ◽  
James P Catlin ◽  
Christine E Schaner Tooley
Keyword(s):  
Cell Differentiation ◽  
Muscle Cell ◽  
Transcriptional Activation ◽  
Type I Collagen ◽  
Muscle Differentiation ◽  
C2c12 Cells ◽  
Myoblast Differentiation ◽  
Serum Starvation ◽  
Type I ◽  
Muscle Cell Differentiation

The N-terminal methyltransferase NRMT1 is an important regulator of protein-DNA interactions and plays a role in many cellular processes, including mitosis, cell cycle progression, chromatin organization, DNA damage repair, and transcriptional regulation. Accordingly, loss of NRMT1 results in both developmental pathologies and oncogenic phenotypes. Though NRMT1 plays such important and diverse roles in the cell, little is known about its own regulation. To better understand the mechanisms governing NRMT1 expression, we first identified its predominant transcriptional start site and minimal promoter region with predicted transcription factor motifs. We then used a combination of luciferase and binding assays to confirm CREB1 as the major regulator of NRMT1 transcription. We tested which conditions known to activate CREB1 also activated NRMT1 transcription, and found CREB1-mediated NRMT1 expression was increased during recovery from serum starvation and muscle cell differentiation. To determine how NRMT1 expression affects myoblast differentiation, we used CRISPR/Cas9 technology to knock out NRMT1 expression in immortalized C2C12 mouse myoblasts. C2C12 cells depleted of NRMT1 lacked Pax7 expression and were unable to proceed down the muscle differentiation pathway. Instead, they took on characteristics of C2C12 cells that have transdifferentiated into osteoblasts, including increased alkaline phosphatase and type I collagen expression and decreased proliferation. These data implicate NRMT1 as an important downstream target of CREB1 during muscle cell differentiation.

scholarly journals The Leucine Catabolite and Dietary Supplement β-Hydroxy-β-Methyl Butyrate (HMB) as an Epigenetic Regulator in Muscle Progenitor Cells

Metabolites ◽  
2021 ◽  
Vol 11 (8) ◽  
pp. 512
Author(s):  
Virve Cavallucci ◽  
Giovambattista Pani
Keyword(s):  
Histone Acetylation ◽  
Dietary Supplement ◽  
Hdac Inhibitor ◽  
Muscle Wasting ◽  
C2c12 Cells ◽  
Myoblast Differentiation ◽  
Epigenetic Mark ◽  
Epigenetic Regulator ◽  
Methyl Butyrate

β-Hydroxy-β-Methyl Butyrate (HMB) is a natural catabolite of leucine deemed to play a role in amino acid signaling and the maintenance of lean muscle mass. Accordingly, HMB is used as a dietary supplement by sportsmen and has shown some clinical effectiveness in preventing muscle wasting in cancer and chronic lung disease, as well as in age-dependent sarcopenia. However, the molecular cascades underlying these beneficial effects are largely unknown. HMB bears a significant structural similarity with Butyrate and β-Hydroxybutyrate (βHB), two compounds recognized for important epigenetic and histone-marking activities in multiple cell types including muscle cells. We asked whether similar chromatin-modifying actions could be assigned to HMB as well. Exposure of murine C2C12 myoblasts to millimolar concentrations of HMB led to an increase in global histone acetylation, as monitored by anti-acetylated lysine immunoblotting, while preventing myotube differentiation. In these effects, HMB resembled, although with less potency, the histone deacetylase (HDAC) inhibitor Sodium Butyrate. However, initial studies did not confirm a direct inhibitory effect of HMB on HDACs in vitro. β-Hydroxybutyrate, a ketone body produced by the liver during starvation or intense exercise, has a modest effect on histone acetylation of C2C12 cells or in vitro HDAC inhibitor activities, and, unlike Butyrate and HMB, did not interfere with myotube formation in a myoblast differentiation assay. Instead, βHB dramatically increased lysine β-hydroxybutyrylation (Kbhb) of histone tails, an epigenetic mark associated with fasting responses and muscle catabolic states. However, when C2C12 cells were exposed to βHB in the presence of equimolar HMB this chromatin modification was drastically reduced, pointing to a role for HMB in attenuating ketosis-associated muscle wasting. In conclusion, while their mechanistic underpinnings remain to be clarified, these preliminary observations highlight novel and potentially important activities of HMB as an epigenetic regulator and βHB antagonist in muscle precursor cells, to be further explored in their biomedical implications.

scholarly journals Surgical procedures suppress autophagic flux in the kidney

2021 ◽  
Vol 12 (3) ◽  
Author(s):  
Carolyn N. Brown ◽  
Daniel Atwood ◽  
Deepak Pokhrel ◽  
Sara J. Holditch ◽  
Christopher Altmann ◽  
...  
Keyword(s):  
Inflammatory Cytokines ◽  
Mammalian Target Of Rapamycin ◽  
Kidney Injury ◽  
Compensatory Hypertrophy ◽  
Autophagic Flux ◽  
Bafilomycin A1 ◽  
Concomitant Increase ◽  
Sham Surgery ◽  
And Function ◽  
Pro Inflammatory Cytokines

AbstractMany surgical models are used to study kidney and other diseases in mice, yet the effects of the surgical procedure itself on the kidney and other tissues have not been elucidated. In the present study, we found that both sham surgery and unilateral nephrectomy (UNX), which is used as a model of renal compensatory hypertrophy, in mice resulted in increased mammalian target of rapamycin complex 1/2 (mTORC1/2) in the remaining kidney. mTORC1 is known to regulate lysosomal biogenesis and autophagy. Genes associated with lysosomal biogenesis and function were decreased in sham surgery and UNX kidneys. In both sham surgery and UNX, there was suppressed autophagic flux in the kidney as indicated by the lack of an increase in LC3-II or autophagosomes seen on immunoblot, IF and EM after bafilomycin A1 administration and a concomitant increase in p62, a marker of autophagic cargo. There was a massive increase in pro-inflammatory cytokines, which are known to activate ERK1/2, in the serum after sham surgery and UNX. There was a large increase in ERK1/2 in sham surgery and UNX kidneys, which was blocked by the MEK1/2 inhibitor, trametinib. Trametinib also resulted in a significant decrease in p62. In summary, there was an intense systemic inflammatory response, an ERK-mediated increase in p62 and suppressed autophagic flux in the kidney after sham surgery and UNX. It is important that researchers are aware that changes in systemic pro-inflammatory cytokines, ERK1/2 and autophagy can be caused by sham surgery as well as the kidney injury/disease itself.

PGC-1α is associated with C2C12 Myoblast differentiation

2014 ◽  
Vol 9 (11) ◽  
pp. 1030-1036 ◽  
Author(s):  
Yaqiu Lin ◽  
Yanying Zhao ◽  
Ruiwen Li ◽  
Jiaqi Gong ◽  
Yucai Zheng ◽  
...  
Keyword(s):  
Mrna Level ◽  
Biological Significance ◽  
C2c12 Cells ◽  
Myoblast Differentiation ◽  
C2c12 Myoblast ◽  
Mrna Levels ◽  
Transfected Cells ◽  
Myosin Heavy Chain Isoform ◽  
Important Mediator

AbstractPGC-1α has been implicated as an important mediator of functional capacity of skeletal muscle. However, the role of PGC-1α in myoblast differentiation remains unexplored. In the present study, we observed a significant up-regulation of PGC-1α expression during the differentiation of murine C2C12 myoblast. To understand the biological significance of PGC-1α up-regulation in myoblast differentiation, C2C12 cells were transfected with murine PGC-1α cDNA and siRNA targeting PGC-1α, respectively. PGC-1α over-expressing clones fused to form typical myotubes with higher mRNA level of myosin heavy chain isoform I (MyHCI) and lower MyHCIIX. No obvious differentiation was observed in PGC-1α-targeted siRNA-transfected cells with marked decrement of mRNA levels of MyHCI and MyHCIIX. Furthermore, PGC-1α increased the expression of MyoD and MyoG in C2C12 cells, which controlled the commitment of precursor cells to myotubes. These results indicate that PGC-1α is associated with myoblast differentiation and elevates MyoD and MyoG expression levels in C2C12 cells.

scholarly journals S6K1 Is Indispensible for Stress-Induced Microtubule Acetylation and Autophagic Flux

Cells ◽  
2021 ◽  
Vol 10 (4) ◽  
pp. 929
Author(s):  
Aleksandra Hać ◽  
Karolina Pierzynowska ◽  
Anna Herman-Antosiewicz
Keyword(s):  
Degradation Process ◽  
Underlying Mechanism ◽  
Stress Conditions ◽  
Autophagic Flux ◽  
Ratiometric Fluorescence ◽  
Mouse Embryonic Fibroblasts ◽  
Double Knockout ◽  
Embryonic Fibroblasts ◽  
Microtubule Network ◽  
Tubulin Acetylation

Autophagy is a specific macromolecule and organelle degradation process. The target macromolecule or organelle is first enclosed in an autophagosome, and then delivered along acetylated microtubules to the lysosome. Autophagy is triggered by stress and largely contributes to cell survival. We have previously shown that S6K1 kinase is essential for autophagic flux under stress conditions. Here, we aimed to elucidate the underlying mechanism of S6K1 involvement in autophagy. We stimulated autophagy in S6K1/2 double-knockout mouse embryonic fibroblasts by exposing them to different stress conditions. Transient gene overexpression or silencing, immunoblotting, immunofluorescence, flow cytometry, and ratiometric fluorescence analyses revealed that the perturbation of autophagic flux in S6K1-deficient cells did not stem from impaired lysosomal function. Instead, the absence of S6K1 abolished stress-induced tubulin acetylation and disrupted the acetylated microtubule network, in turn impairing the autophagosome-lysosome fusion. S6K1 overexpression restored tubulin acetylation and autophagic flux in stressed S6K1/2-deficient cells. Similar effect of S6K1 status was observed in prostate cancer cells. Furthermore, overexpression of an acetylation-mimicking, but not acetylation-resistant, tubulin variant effectively restored autophagic flux in stressed S6K1/2-deficient cells. Collectively, S6K1 controls tubulin acetylation, hence contributing to the autophagic flux induced by different stress conditions and in different cells.

Reduction of myoblast differentiation following multiple population doublings in mouse C2C12 cells: A model to investigate ageing?

2011 ◽  
Vol 112 (12) ◽  
pp. 3773-3785 ◽  
Author(s):  
Adam P. Sharples ◽  
Nasser Al-Shanti ◽  
Mark P. Lewis ◽  
Claire E. Stewart
Keyword(s):  
C2c12 Cells ◽  
Myoblast Differentiation ◽  
Multiple Population ◽  
Population Doublings

scholarly journals Primary Cilia Blockage Promotes the Malignant Behaviors of Hepatocellular Carcinoma via Induction of Autophagy

2019 ◽  
Vol 2019 ◽  
pp. 1-14
Author(s):  
Lian Liu ◽  
Jia-Qi Sheng ◽  
Mu-Ru Wang ◽  
Yun Gan ◽  
Xiao-Li Wu ◽  
...  
Keyword(s):  
Hepatocellular Carcinoma ◽  
Primary Cilia ◽  
The Cancer Genome Atlas ◽  
Migration And Invasion ◽  
Serum Starvation ◽  
Autophagic Flux ◽  
And Function ◽  
Hcc Cells

Primary cilia are organelles protruding from cell surface into environment that function in regulating cell cycle and modulating cilia-related signal. Primary ciliogenesis and autophagy play important roles in tumorigenesis. However, the functions and interactions between primary cilia and autophagy in hepatocellular carcinoma (HCC) have not been reported yet. Here, we aimed to investigate the relationship and function of primary cilia and autophagy in HCC. In vitro, we showed that serum starvation stimuli could trigger primary ciliogenesis in HCC cells. Blockage of primary ciliogenesis by IFT88 silencing enhanced the proliferation, migration, and invasion ability of HCC cells. In addition, inhibition of primary cilia could positively regulate autophagy. However, the proliferation, migration, and invasion ability which were promoted by IFT88 silencing could be partly reversed by inhibition of autophagy. In vivo, interference of primary cilia led to acceleration of tumor growth and increase of autophagic flux in xenograft HCC mouse models. Moreover, IFT88 high expression or ATG7 low expression in HCC tissues was correlated with longer survival time indicated by the Cancer Genome Atlas (TCGA) analysis. In conclusion, our study demonstrated that blockage of primary ciliogenesis by IFT88 silencing had protumor effects through induction of autophagy in HCC. These findings define a newly recognized role of primary cilia and autophagy in HCC.

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