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Abstract
Apoptosis is a primary characteristic in the pathogenesis of liver disease. Hepatic apoptosis is regulated by autophagic activity. However, mechanisms mediating their interaction remain to be determined. Basal level of autophagy ensures the physiological turnover of old and damaged organelles. Autophagy also is an adaptive response under stressful conditions. Autophagy can control cell fate through different cross-talk signals. A complex interplay between hepatic autophagy and apoptosis determines the degree of hepatic apoptosis and the progression of liver disease as demonstrated by pre-clinical models and clinical trials. This review summarizes recent advances on roles of autophagy that plays in pathophysiology of liver. The autophagic pathway can be a novel therapeutic target for liver disease.
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Key Words
- ALT, alanine aminotransferase
- AMBRA-1, activating molecule in Beclin-1-regulated autophagy
- APAP, N-acetyl-p-aminophenol
- ATP, adenosine triphosphate
- Atg, autophagy-related gene
- BH3, Bcl-2 homology domain-3
- BNIP, Bcl-2/adenovirus E1B 19 kd-interacting protein
- Barkor, Beclin-1-associated autophagy-related key regulator
- Bcl-2, B-cell lymphoma-2
- Bcl-xL, B-cell lymphoma extra long
- Beclin-1, Bcl-2-interacting protein-1
- CSE, cigarette smoke extract
- DISC, death-inducing signaling complex
- DNA, DNA
- DRAM, damage regulated autophagic modulator
- Drp1, dynamin-related protein 1
- ER stress, endoplasmic reticulum stress
- FADD, Fas-associated protein with death domain
- FFA, free fatty acids
- HBV, hepatitis B virus
- HBx, hepatitis B X protein
- HCC, hepatocellular carcinoma
- HCV, hepatitis C virus
- HSC, hepatic stellate cells
- LAMP-2, lysosome-associated membrane protein 2
- LD, lipid droplets
- MDBs, Mallory-Denk bodies
- MOMP, mitochondrial outer membrane permiabilization
- Microtubule LC3, microtubule light chain 3
- PCD, programmed cell death
- PI3KC3, phosphatidylinositol-3-kinase class-3
- RNA, ribonucleic acid
- ROS, reactive oxygen species
- TNFα, tumor necrosis factor-α
- TUNEL, terminal deoxynucleotidyl transferase dUTP nick-end labeling
- UVRAG, UV-resistance-associated gene
- Vps34, vacuolar protein sorting-34
- apoptosis
- autophagy
- c-FLIP, cellular FLICE-like inhibitor protein
- cross-talk
- liver injury
- mTOR, mammalian target of rapamycin
- mechanism
- siRNA, small interfering RNA
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Affiliation(s)
- Kewei Wang
- a Departments of Surgery; University of Illinois College of Medicine ; Peoria , IL , USA
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Takemoto K, Hatano E, Iwaisako K, Takeiri M, Noma N, Ohmae S, Toriguchi K, Tanabe K, Tanaka H, Seo S. Necrostatin-1 protects against reactive oxygen species (ROS)-induced hepatotoxicity in acetaminophen-induced acute liver failure. FEBS Open Bio. 2014;4:777-787. [PMID: 25349782 PMCID: PMC4208088 DOI: 10.1016/j.fob.2014.08.007] [Citation(s) in RCA: 111] [Impact Index Per Article: 11.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2014] [Revised: 08/29/2014] [Accepted: 08/30/2014] [Indexed: 12/13/2022] Open
Abstract
RIPK-dependent necrosis is involved in acetaminophen (APAP)-induced hepatotoxicity. Necrostatin-1 (Nec-1) protects mice against APAP-induced acute liver damage. Nec-1 suppresses APAP-induced ROS generation in hepatocytes. Nec-1 promotes resistance to oxidative stress in hepatocytes.
Excessive acetaminophen (APAP) use is one of the most common causes of acute liver failure. Various types of cell death in the damaged liver are linked to APAP-induced hepatotoxicity, and, of these, necrotic cell death of hepatocytes has been shown to be involved in disease pathogenesis. Until recently, necrosis was commonly considered to be a random and unregulated form of cell death; however, recent studies have identified a previously unknown form of programmed necrosis called receptor-interacting protein kinase (RIPK)-dependent necrosis (or necroptosis), which is controlled by the kinases RIPK1 and RIPK3. Although RIPK-dependent necrosis has been implicated in a variety of disease states, including atherosclerosis, myocardial organ damage, stroke, ischemia–reperfusion injury, pancreatitis, and inflammatory bowel disease. However its involvement in APAP-induced hepatocyte necrosis remains elusive. Here, we showed that RIPK1 phosphorylation, which is a hallmark of RIPK-dependent necrosis, was induced by APAP, and the expression pattern of RIPK1 and RIPK3 in the liver overlapped with that of CYP2E1, whose activity around the central vein area has been demonstrated to be critical for the development of APAP-induced hepatic injury. Moreover, a RIPK1 inhibitor ameliorated APAP-induced hepatotoxicity in an animal model, which was underscored by significant suppression of the release of hepatic enzymes and cytokine expression levels. RIPK1 inhibition decreased reactive oxygen species levels produced in APAP-injured hepatocytes, whereas CYP2E1 expression and the depletion rate of total glutathione were unaffected. Of note, RIPK1 inhibition also conferred resistance to oxidative stress in hepatocytes. These data collectively demonstrated a RIPK-dependent necrotic mechanism operates in the APAP-injured liver and inhibition of this pathway may be beneficial for APAP-induced fulminant hepatic failure.
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Key Words
- ABTS, 2,2′-azino-bis (3-ethylbenzothiazoline)-6-sulfonic acid
- ALF, acute liver failure
- ALT, alanine aminotransferase
- APAP, acetaminophen
- AST, aspartate aminotransferase
- Acetaminophen
- Acute liver failure
- CM-H2DCFDA, 5-(and-6)-chloromethyl-2′,7′-dichlorodihydrofluorescein diacetate, acetyl ester
- CXCL1, chemokine (C-X-C motif) ligand 1
- CYP2E1, cytochrome P450 2E1
- DMSO, dimethyl sulfoxide
- Drp1, dynamin-related protein 1
- FBS, fetal bovine serum
- GSH, glutathione
- Hepatocytes
- LDH, lactate dehydrogenase
- NAPQI, N-acetyl-p-benzoquinone
- NO, nitric oxide
- Nec-1, necrostatin-1
- Necroptosis
- PGAM5, phosphoglycerate mutase family member 5
- PI, propidium iodide
- RIPK, receptor-interacting protein kinase
- RIPK-dependent necrosis
- ROS, reactive oxygen species
- Reactive oxygen species
- SNAP, S-nitroso-N-acetyl-dl-penicillamine
- WST-8, 2-(2-methoxy-4-nitrophenyl)-3-(4-nitrophenyl)-5-(2,4-disulfophenyl)-2H-tetrazolium
- bFGF, basic fibroblast growth factor
- λPP, lambda protein phosphatase
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Salabei JK, Hill BG. Mitochondrial fission induced by platelet-derived growth factor regulates vascular smooth muscle cell bioenergetics and cell proliferation. Redox Biol 2013; 1:542-51. [PMID: 24273737 PMCID: PMC3836280 DOI: 10.1016/j.redox.2013.10.011] [Citation(s) in RCA: 112] [Impact Index Per Article: 10.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/26/2013] [Revised: 10/30/2013] [Accepted: 10/31/2013] [Indexed: 01/09/2023] Open
Abstract
Vascular smooth muscle cells (VSMCs) develop a highly proliferative and synthetic phenotype in arterial diseases. Because such phenotypic changes are likely integrated with the energetic state of the cell, we hypothesized that changes in cellular metabolism regulate VSMC plasticity. VSMCs were exposed to platelet-derived growth factor-BB (PDGF) and changes in mitochondrial morphology, proliferation, contractile protein expression, and mitochondrial metabolism were examined. Exposure of VSMCs to PDGF resulted in mitochondrial fragmentation and a 50% decrease in the abundance of mitofusin 2. Synthetic VSMCs demonstrated a 20% decrease in glucose oxidation, which was accompanied by an increase in fatty acid oxidation. Results of mitochondrial function assays in permeabilized cells showed few changes due to PDGF treatment in mitochondrial respiratory chain capacity and coupling. Treatment of VSMCs with Mdivi-1—an inhibitor of mitochondrial fission—inhibited PDGF-induced mitochondrial fragmentation by 50% and abolished increases in cell proliferation; however, it failed to prevent PDGF-mediated activation of autophagy and removal of contractile proteins. In addition, treatment with Mdivi-1 reversed changes in fatty acid and glucose oxidation associated with the synthetic phenotype. These results suggest that changes in mitochondrial morphology and bioenergetics underlie the hyperproliferative features of the synthetic VSMC phenotype, but do not affect the degradation of contractile proteins. Mitochondrial fragmentation occurring during the transition to the synthetic phenotype could be a therapeutic target for hyperproliferative vascular disorders. PDGF promotes mitochondrial fragmentation in vascular smooth muscle cells. PDGF increases metabolic reliance on fatty acids. Mitochondrial fragmentation regulates proliferation and bioenergetics. PDGF-induced bioenergetic and autophagic responses regulate de-differentiation.
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Key Words
- ADP, adenine dinucleotide phosphate
- ATP5A1, ATP synthase, H+ transporting, mitochondrial F1 complex, alpha subunit 1
- ATP5B, ATP synthase, H+ transporting, mitochondrial F1 complex, beta polypeptide
- Atherosclerosis
- CPT1, carnitine palmitoyl transferase 1
- DMEM, Delbucco's Eagle Modified Medium
- Drp1, dynamin-related protein 1
- EDTA, ethylenediaminetetraacetic acid
- EGTA, ethylene glycol tetraacetic acid
- Extracellular flux
- FBS, fetal bovine serum
- FCCP, Carbonyl cyanide 4-(trifluoromethoxy)phenylhydrazone
- Fis1, mitochondrial fission 1 protein
- Fusion
- HEPES, 4-(2-hydroxyethyl)-1-piperazineethanesulfonic acid
- LC3, (microtubule-associated protein 1 light chain 3)
- MOPS, 3-(N-morpholino)propanesulfonic acid
- Metabolism
- NDUFB8, NADH dehydrogenase (ubiquinone) 1 beta subcomplex, 8
- NP-40, noniodet P40
- Opa1, optic atrophy 1
- Oxidative phosphorylation
- PCNA, proliferating cell nuclear antigen
- PDGF-BB, platelet-derived growth factor-BB
- PVDF, polyvinylidene fluoride
- Restenosis
- SDHB, succinate dehydrogenase subunit B
- SDS, sodium dodecyl sulfate
- TMPD, N,N,N′,N′-tetramethyl-p-phenylenediamine
- VSMC, vascular smooth muscle cells
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Affiliation(s)
- Joshua K. Salabei
- Diabetes and Obesity Center, Institute of Molecular Cardiology, University of Louisville School of Medicine, Louisville, KY 40202, USA
| | - Bradford G. Hill
- Diabetes and Obesity Center, Institute of Molecular Cardiology, University of Louisville School of Medicine, Louisville, KY 40202, USA
- Department of Biochemistry and Molecular Biology, University of Louisville School of Medicine, Louisville, KY 40202, USA
- Department of Physiology and Biophysics, University of Louisville School of Medicine, Louisville, KY 40202, USA
- Correspondence to: Diabetes and Obesity Center, Institute of Molecular Cardiology, University of Louisville School of Medicine, Delia Baxter Building, Room 404A, 580 South Preston Street, Louisville, KY 40202 United States. Tel.: +1 502 852 1015; fax: +1 502 852 3663.
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Urban MJ, Li C, Yu C, Lu Y, Krise JM, McIntosh MP, Rajewski RA, Blagg BS, Dobrowsky RT. Inhibiting heat-shock protein 90 reverses sensory hypoalgesia in diabetic mice. ASN Neuro 2010; 2:e00040. [PMID: 20711301 DOI: 10.1042/AN20100015] [Citation(s) in RCA: 56] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/04/2010] [Revised: 07/08/2010] [Accepted: 07/14/2010] [Indexed: 01/07/2023] Open
Abstract
Increasing the expression of Hsp70 (heat-shock protein 70) can inhibit sensory neuron degeneration after axotomy. Since the onset of DPN (diabetic peripheral neuropathy) is associated with the gradual decline of sensory neuron function, we evaluated whether increasing Hsp70 was sufficient to improve several indices of neuronal function. Hsp90 is the master regulator of the heat-shock response and its inhibition can up-regulate Hsp70. KU-32 (N-{7-[(2R,3R,4S,5R)-3,4-dihydroxy-5-methoxy-6,6-dimethyl-tetrahydro-2H-pyran-2-yloxy]-8-methyl-2-oxo-2H-chromen-3-yl}acetamide) was developed as a novel, novobiocin-based, C-terminal inhibitor of Hsp90 whose ability to increase Hsp70 expression is linked to the presence of an acetamide substitution of the prenylated benzamide moiety of novobiocin. KU-32 protected against glucose-induced death of embryonic DRG (dorsal root ganglia) neurons cultured for 3 days in vitro. Similarly, KU-32 significantly decreased neuregulin 1-induced degeneration of myelinated Schwann cell DRG neuron co-cultures prepared from WT (wild-type) mice. This protection was lost if the co-cultures were prepared from Hsp70.1 and Hsp70.3 KO (knockout) mice. KU-32 is readily bioavailable and was administered once a week for 6 weeks at a dose of 20 mg/kg to WT and Hsp70 KO mice that had been rendered diabetic with streptozotocin for 12 weeks. After 12 weeks of diabetes, both WT and Hsp70 KO mice developed deficits in NCV (nerve conduction velocity) and a sensory hypoalgesia. Although KU-32 did not improve glucose levels, HbA1c (glycated haemoglobin) or insulin levels, it reversed the NCV and sensory deficits in WT but not Hsp70 KO mice. These studies provide the first evidence that targeting molecular chaperones reverses the sensory hypoalgesia associated with DPN.
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Key Words
- AM, acetoxymethyl ester
- DAPI, 4′,6-diamidino-2-phenylindole
- DMEM, Dulbecco's modified Eagle's medium
- DPN, diabetic peripheral neuropathy
- DRG, dorsal root ganglion
- Drp1, dynamin-related protein 1
- FBG, fasting blood glucose
- FCS, fetal calf serum
- HSF1, heat-shock factor 1
- HSR, heat-shock response
- Hsc70, heat-shock cognate 70 stress protein
- Hsp90, heat-shock protein 90
- JNK, c-Jun N-terminal kinase
- KO, knockout
- KU-32, N-{7-[(2R,3R,4S,5R)-3,4-dihydroxy-5-methoxy-6,6-dimethyl-tetrahydro-2H-pyran-2-yloxy]-8-methyl-2-oxo-2H-chromen-3-yl}acetamide
- LC-MS, liquid chromatography MS
- MBP, myelin basic protein
- MNCV, motor NCV
- NCV, nerve conduction velocity
- NGF, nerve growth factor
- NRG1, human recombinant neuregulin-1-β1 epidermal growth factor domain
- SC-DRG, Schwann cell DRG
- SNCV, sensory NCV
- STZ, streptozotocin
- WT, wild-type
- diabetic neuropathy
- dorsal root ganglia neuron
- heat-shock protein 70
- molecular chaperone
- nerve conduction velocity
- neurodegeneration
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Uittenbogaard M, Baxter KK, Chiaramello A. The neurogenic basic helix-loop-helix transcription factor NeuroD6 confers tolerance to oxidative stress by triggering an antioxidant response and sustaining the mitochondrial biomass. ASN Neuro 2010; 2:e00034. [PMID: 20517466 DOI: 10.1042/AN20100005] [Citation(s) in RCA: 52] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/08/2010] [Revised: 04/09/2010] [Accepted: 04/21/2010] [Indexed: 12/21/2022] Open
Abstract
Preserving mitochondrial mass, bioenergetic functions and ROS (reactive oxygen species) homoeostasis is key to neuronal differentiation and survival, as mitochondria produce most of the energy in the form of ATP to execute and maintain these cellular processes. In view of our previous studies showing that NeuroD6 promotes neuronal differentiation and survival on trophic factor withdrawal, combined with its ability to stimulate the mitochondrial biomass and to trigger comprehensive antiapoptotic and molecular chaperone responses, we investigated whether NeuroD6 could concomitantly modulate the mitochondrial biomass and ROS homoeostasis on oxidative stress mediated by serum deprivation. In the present study, we report a novel role of NeuroD6 as a regulator of ROS homoeostasis, resulting in enhanced tolerance to oxidative stress. Using a combination of flow cytometry, confocal fluorescence microscopy and mitochondrial fractionation, we found that NeuroD6 sustains mitochondrial mass, intracellular ATP levels and expression of specific subunits of respiratory complexes upon oxidative stress triggered by withdrawal of trophic factors. NeuroD6 also maintains the expression of nuclear-encoded transcription factors, known to regulate mitochondrial biogenesis, such as PGC-1α (peroxisome-proliferator-activated receptor γ co-activator-1α), Tfam (transcription factor A, mitochondrial) and NRF-1 (nuclear respiratory factor-1). Finally, NeuroD6 triggers a comprehensive antioxidant response to endow PC12-ND6 cells with intracellular ROS scavenging capacity. The NeuroD6 effect is not limited to the classic induction of the ROS-scavenging enzymes, such as SOD2 (superoxide dismutase 2), GPx1 (glutathione peroxidase 1) and PRDX5 (peroxiredoxin 5), but also to the recently identified powerful ROS suppressors PGC-1α, PINK1 (phosphatase and tensin homologue-induced kinase 1) and SIRT1. Thus our collective results support the concept that the NeuroD6–PGC-1α–SIRT1 neuroprotective axis may be critical in co-ordinating the mitochondrial biomass with the antioxidant reserve to confer tolerance to oxidative stress.
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Key Words
- AD, Alzheimer’s disease
- AM, acetoxymethyl ester
- COX, cytochrome c oxidase
- DAPI, 4′,6-diamidino-2-phenylindole
- DIC, differential interference contrast
- Drp1, dynamin-related protein 1
- ETC, electron transfer chain
- GABP-α, GA-binding protein-α
- GAPDH, glyceraldehyde-3-phosphate dehydrogenase
- GFP, green fluorescent protein
- GPx1, glutathione peroxidase 1
- HSP, heat-shock protein
- MMP, mitochondrial membrane potential
- MTG, MitoTracker® Green
- MTR, MitoTracker® Red
- Mfn2, mitofusin 2
- Mg-Gr, Magnesium Green
- NRF, nuclear respiratory factor
- NT-PGC-1α, N-terminal-truncated PGC-1α
- NeuroD family
- OPA1, optic atrophy 1
- OXPHOS, oxidative phosphorylation
- PDL, poly-d-lysine
- PGC-1α, peroxisome-proliferator-activated receptor γ co-activator-1α
- PINK1, phosphatase and tensin homologue-induced kinase 1
- PRDX5, peroxiredoxin 5
- ROS, reactive oxygen species
- SIRT1
- SOD, superoxide dismutase
- Tfam, transcription factor A, mitochondrial
- WGA, wheatgerm agglutinin
- bHLH, basic helix–loop–helix
- mitochondria
- mtDNA, mitochondrial DNA
- neuronal survival
- reactive oxygen species (ROS)
- transcriptional co-regulator peroxisome-proliferator-activated receptor γ co-activator-1α (PGC-1α)
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