geranylgeranylacetone and Reperfusion-Injury

In response to stresses, mammalian cells induce heat shock proteins (HSP). Overproduction of a stress-inducible 70-kDa protein (Hsp70) results in the acquisition of tolerance against various types of stresses. An acyclic isoprenoid, geranylgeranylacetone (GGA), was introduced for the first time as a non-toxic Hsp 70 inducer, which selectively and safely induced Hsp70 in cultured guinea pig gastric mucosal cells and rat gastric mucosa. GGA also primed other types of cells for enhanced induction of Hsp70, when exposed to stress. Pretreatment of rats with GGA markedly suppressed ischemia-reperfusion injury of the liver, small intestine, or heart, and improved survival after 95% hepatectomy as well as liver transplantation. GGA can block insult-induced apoptosis at multiple levels; it inhibited activation of c-Jun N-terminal kinases, decline of mitochondrial membrane potential, and formation of apoptosome by binding with Apaf-1. Recently, GGA has been shown to induce thioredoxin and anti-viral genes, suggesting that GGA may exhibit protective actions independently of Hsp70 induction. HSP are members of molecular chaperones that are essential for the quality control of intracellular proteins. New compounds specifically targeting molecular chaperones that function to prevent the accumulation of misfolded proteins may be useful for the treatment of neurodegenerative disorders in the near future.

Topics: Animals; Apoptosis; Cytoprotection; Digestive System Diseases; Diterpenes; Gastric Mucosa; Guinea Pigs; HSP70 Heat-Shock Proteins; Humans; JNK Mitogen-Activated Protein Kinases; Membrane Potentials; Mitochondria; Mitogen-Activated Protein Kinases; Neurodegenerative Diseases; Rats; Reperfusion Injury

Retinal ischemia-reperfusion (I/R) injury is a common pathophysiological stress state connected to various diseases, including acute glaucoma, retinal vascular obstruction, and diabetic retinopathy. Recent studies have suggested that geranylgeranylacetone (GGA) could increase heat shock protein70 (HSP70) level and reduce retinal ganglion cells (RGCs) apoptosis in a rat retinal I/R model. However, the underlying mechanism remains unclear. Moreover, the injury caused by retinal I/R includes not only apoptosis but also autophagy and gliosis, and the effects of GGA on autophagy and gliosis have not been reported. Our study established a retinal I/R model by anterior chamber perfusion pressuring to 110 mmHg for 60 min, followed by 4 h of reperfusion. The levels of HSP70, apoptosis-related proteins, GFAP, LC3-II, and PI3K/AKT/mTOR signaling proteins were determined by western blotting and qPCR after treatment with GGA, HSP70 inhibitor quercetin (Q), PI3K inhibitor LY294002, and mTOR inhibitor rapamycin. Apoptosis was evaluated by TUNEL staining, meanwhile, HSP70 and LC3 were detected by immunofluorescence. Our results demonstrated that GGA-induced HSP70 expression significantly reduced gliosis, autophagosome accumulation, and apoptosis in retinal I/R injury, indicating that GGA exerted protective effects on retinal I/R injury. Moreover, the protective effects of GGA mechanistically relied on the activation of PI3K/AKT/mTOR signaling. In conclusion, GGA-induced HSP70 overexpression has protective effects on retinal I/R injury by activating PI3K/AKT/mTOR signaling.

Topics: Animals; Apoptosis; Gliosis; Heat-Shock Response; HSP70 Heat-Shock Proteins; Phosphatidylinositol 3-Kinases; Proto-Oncogene Proteins c-akt; Rats; Reperfusion Injury; Retinal Diseases; TOR Serine-Threonine Kinases

We previously reported that heat shock protein 27 (HSP27) phosphorylation plays an important role in the activation of glucose-6-phosphate dehydrogenase (G6PD), resulting in the upregulation of the pentose phosphate pathway and antioxidant effects against cerebral ischemia-reperfusion injury. The present study investigated the effect of geranylgeranylacetone, an inducer of HSP27, on ischemia-reperfusion injury in male rats as a preliminary study to see if further research of the effects of geranylgeranylacetone on the ischemic stroke was warranted.. In all experiments, male Wistar rats were used. First, we conducted pathway activity profiling based on a gas chromatography-mass spectrometry to identify ischemia-reperfusion-related metabolic pathways. Next, we investigated the effects of geranylgeranylacetone on the pentose phosphate pathway and ischemia-reperfusion injury by real-time polymerase chain reaction (RT-PCR), immunoblotting, and G6PD activity, protein carbonylation and infarct volume analysis. Geranylgeranylacetone or vehicle was injected intracerebroventricularly 3 h prior to middle cerebral artery occlusion or sham operation.. Pathway activity profiling demonstrated that changes in the metabolic state depended on reperfusion time and that the pentose phosphate pathway and taurine-hypotaurine metabolism pathway were the most strongly related to reperfusion among 137 metabolic pathways. RT-PCR demonstrated that geranylgeranylacetone did not significantly affect the increase in HSP27 transcript levels after ischemia-reperfusion. Immunoblotting showed that geranylgeranylacetone did not significantly affect the elevation of HSP27 protein levels. However, geranylgeranylacetone significantly increase the elevation of phosphorylation of HSP27 after ischemia-reperfusion. In addition, geranylgeranylacetone significantly affected the increase in G6PD activity, and reduced the increase in protein carbonylation after ischemia-reperfusion. Accordingly, geranylgeranylacetone significantly reduced the infarct size (median 31.3% vs 19.9%, p = 0.0013).. As a preliminary study, these findings suggest that geranylgeranylacetone may be a promising agent for the treatment of ischemic stroke and would be worthy of further study. Further studies are required to clearly delineate the mechanism of geranylgeranylacetone-induced HSP27 phosphorylation in antioxidant effects, which may guide the development of new approaches for minimizing the impact of cerebral ischemia-reperfusion injury.

Topics: Animals; Brain Ischemia; Diterpenes; HSP27 Heat-Shock Proteins; Male; Neuroprotective Agents; Phosphorylation; Rats; Rats, Wistar; Reperfusion Injury

X‑linked inhibitor of apoptosis protein (XIAP) negatively regulates apoptotic pathways at a post‑mitochondrial level. XIAP functions by directly binding and inhibiting activation of specific caspases. Upon apoptotic stimuli, mitochondrial second mitochondria‑derived activator of caspases (Smac)/direct IAP‑binding protein with low PI (Diablo) is released into the cytosol, which results in displacement of XIAP from caspases. Heat shock protein 72 (HSP72), an anti‑apoptotic protein, prevents mitochondrial injury resulting from acute renal ischemia/reperfusion (I/R), its role in Smac/Diablo and XIAP signaling remains to be elucidated. In the present study, the hypothesis that HSP72 prevents XIAP degradation in vivo and in vitro was assessed. To this purpose, a rat model of I/R injury was used to investigate the renoprotective role of HSP72 by treatment with geranylgeranylacetone (GGA), a specific inducer of HSP72. The mechanism of the cytoprotective properties of HSP72 was also investigated in vitro using adenovirus‑mediated overexpression of HSP72 in adenosine triphosphate (ATP)‑depleted human kidney 2 (HK‑2) cells. Pre‑conditioning rats with GGA attenuated renal tubular cell damage, reduced cell apoptosis, preserved XIAP protein content and improved renal function following I/R injury. An in vitro study was performed in which cells were transiently exposed to 5 mM sodium cyanide in a glucose‑free medium in order to induce apoptosis. Compared with the control, overexpression of HSP72 inhibited Smac/Diablo release from the mitochondria and increased levels of XIAP and pro‑caspase 3 in ATP‑depleted HK‑2 cells. In addition, HSP72 interacted with Smac/Diablo. The present data demonstrates that HSP72 preserves renal function in I/R injury through its anti‑apoptotic effects, which act by suppressing mitochondrial Smac/Diablo release and preserving XIAP protein content.

Topics: Animals; Apoptosis; Apoptosis Regulatory Proteins; Carrier Proteins; Caspase 3; Cell Line, Transformed; Diterpenes; HSP72 Heat-Shock Proteins; Humans; Ischemic Preconditioning; Kidney; Mitochondrial Proteins; Protein Stability; Proteolysis; Rats; Reperfusion Injury; X-Linked Inhibitor of Apoptosis Protein

Cerebral ischemia and reperfusion (I/R) can trigger a cytotoxic cascade with overflow of reactive oxygen species, paradoxically causing neurological dysfunction, redox imbalance, inflammation and apoptosis. The present study aims to investigate the effect of geranylgeranylacetone(GGA) on cerebral I/R injury and the underlying mechanism. The results demonstrated that cerebral I/R increased the neurological function abnormality, brain edema, inflammation and oxidative injury in rats as well as the cognitive impairment, which was significantly reversed by GGA in a dose-dependent manner. GGA also suppressed the cell injury and apoptosis caused by cerebral I/R. Moreover, the protective effect of GGA was found to involve heat shock protein 90 (HSP90) and phosphorylated endothelial nitric oxide synthase (eNOS) expression and activity. Both the HSP90 and eNOS inhibitor abolished the effect of GGA. The data showed that GGA could protect rats against cerebral I/R injury, which may be related to the induction of HSP90 and activation of eNOS.

Topics: Animals; Apoptosis; Brain; Brain Edema; Brain Ischemia; Cognition Disorders; Disease Models, Animal; Diterpenes; HSP90 Heat-Shock Proteins; Malondialdehyde; Maze Learning; Neuroimmunomodulation; Neuroprotective Agents; Nitric Oxide Synthase Type III; Phosphorylation; Random Allocation; Rats, Sprague-Dawley; Reperfusion Injury; Treatment Outcome; Tumor Necrosis Factor-alpha

Geranylgeranylacetone (GGA) has been clinically used as an anti-ulcer drug. In the present study, we explored the protective effects of GGA on lung ischemia/reperfusion injury (IRI) and the underlying mechanism. The results demonstrated that GGA ameliorated the lung biochemical and histological alterations induced by IRI, which was reversed by HSP70 inhibition. To further explore the mechanism of GGA action, we focused on NF-kB and thioredoxin (Trx) redox system. It was shown that GGA induced the HSP70 and Trx-1 expression, NF-kB nuclear translocation and activated thioredoxin reductase (TrxR). The Trx-1 expression and TrxR activity was suppressed by HSP70 and NF-kB inhibition, while the nuclear NF-kB p65 expression was suppressed by HSP70 inhibitor. These results indicated that GGA may protect rat lung against IRI by HSP70 and Trx redox system, in which NF-kB pathway may be involved.

Topics: Animals; Anti-Ulcer Agents; Diterpenes; HSP70 Heat-Shock Proteins; Lung; Male; NF-kappa B; Oxidation-Reduction; Rats; Rats, Sprague-Dawley; Reperfusion Injury; Thioredoxins

Recent reports suggest the presence of heat-shock protein (HSP)-reactive T cells with a regulatory phenotype in various inflammatory diseases. To test whether HSP exerts renoprotective effects through regulatory T cells (Tregs), ischemia/reperfusion injury was done with or without heat preconditioning in mice. Splenocytes from heat-preconditioned mice had Treg expansion and a reduced proliferative response upon mitogenic stimulus. T cells from heat-preconditioned mice failed to reconstitute postischemic injury when adoptively transferred to T cell-deficient nu/nu mice in contrast to those from control mice. Tregs were also increased in heat-preconditioned ischemic kidneys. Depleting Tregs before heat preconditioning abolished the renoprotective effect, while adoptive transfer of these cells back into Treg-depleted mice partially restored the beneficial effect of heat preconditioning. Inhibition of HSP70 by quercetin suppressed Treg expansion, as well as renoprotective effects. Transferring Tregs in quercetin-treated heat-preconditioned mice partially restored the beneficial effect of heat preconditioning. The specificity of immune cell HSP70 in renoprotection was confirmed by partial restoration of kidney injury when T cells from HSP70-deficient heat preconditioned mice were adoptively transferred to nu/nu mice. Thus, the renoprotective effect of HSP70 may be partially mediated by a direct immunomodulatory effect through Tregs. Better understanding of immunomodulatory mechanisms of various stress proteins might facilitate discovery of new preventive strategies in acute kidney injury.

Topics: Acute Kidney Injury; Animals; Cell Proliferation; Diterpenes; Forkhead Transcription Factors; Hot Temperature; HSP70 Heat-Shock Proteins; Interleukin-2 Receptor alpha Subunit; Male; Mice; Mice, Inbred C57BL; Mice, Nude; Phenotype; Reperfusion Injury; T-Lymphocytes, Regulatory

The high mobility group box 1 (HMGB1) protein plays an important role in myocardial ischemia and reperfusion (I/R) injury. Geranylgeranylacetone (GGA), a heat shock protein 72 inducer, has been reported to reduce myocardial I/R injury. The aim of this study was to investigate the cardioprotective mechanism of GGA during myocardial I/R injury in rats. Anesthetized male rats were treated once with GGA (200 mg/kg, p.o.) 24 h before ischemia, and subjected to ischemia for 30 min, followed by reperfusion for 4 h. Lactate dehydrogenase (LDH), creatine kinase (CK), malondialdehyde (MDA), superoxide dismutase (SOD) activity and infarct size were measured. HMGB1 expression was assessed by immunoblotting. The results showed that pre-treatment with GGA (200 mg/kg) significantly reduced the infarct size and the levels of LDH and CK after 4 h of reperfusion (all P<0.05). GGA also significantly inhibited the increase in MDA levels and the decrease in SOD levels (both P<0.05). Meanwhile, GGA considerably suppressed the expression of HMGB1 induced by I/R. The present study suggests that GGA is capable of attenuating myocardial I/R injury by inhibiting HMGB1 expression.

Topics: Animals; Cardiotonic Agents; Creatine Kinase; Diterpenes; Gene Expression Regulation; HMGB1 Protein; HSP72 Heat-Shock Proteins; L-Lactate Dehydrogenase; Male; Malondialdehyde; Myocardial Ischemia; Rats; Rats, Sprague-Dawley; Reperfusion Injury; Superoxide Dismutase

To explore a simple, effective, safe and operable pretreatment for conferring tolerance against ischemia-reperfusion (I-R) injury in rat livers.. Forty-five rats were divided into five groups (each group n = 9). Group C: control group; group G: geranylgeranylacetone (GGA) was administered without heat stress; group S: local heat stress alone; group WG: GGA plus whole-body heat stress; group SG: GGA administration plus local heat stress. After completion of the I-R procedure, the ischemic-reperfused liver lobes in five groups were resected and tested for heat shock protein (HSP70) by RT-PCR, Western blotting analysis and immunohistochemical staining. The blood samples were collected for ALT and AST measurement at the end of occlusion of blood supply, 30 min after reperfusion, 24, 48, 72 h after surgery from the inferior vena cava. Survival was monitored for 1 wk.. The production of HSP70 after I-R injury increased, the liver enzyme levels after reperfusion decreased rapidly, and the survival rates increased in groups C-SG.. The combination of GGA plus local somatothermal stimulation is a simple, effective, safe and operable pretreatment to induce HSP70 in patients with liver tumor and cirrhosis before hepatectomy and in donors before harvesting graft for liver transplantation.

Topics: Administration, Oral; Animals; Diterpenes; Gene Expression Regulation; Heat-Shock Response; HSP70 Heat-Shock Proteins; Hyperthermia, Induced; Ischemic Preconditioning; Liver; Male; Rats; Rats, Sprague-Dawley; Reperfusion Injury; RNA, Messenger

The effect of geranyl-geranyl-acetone (GGA) administration before heat shock preconditioning on heat shock protein (HSP) 72 induction and on the acquisition of tolerance against ischemia-reperfusion Injury was studied in rat livers. Male Wistar rats were divided into four groups: a control group (group C); a GGA group (group G); a simple heat shock group (group VH); and a heat shock with GGA premedication group (group GH). Five-, 10-, and 15-minute periods of heat shock preconditioning at 42 degrees C were performed in groups VH and GH. Subgroups were determined according to the period of heat shock exposure. After a 48-hour recovery, rats in groups C, VH5, VH15, and GH5 received a 30-minute period of hepatic ischemia. Induction of HSP72, survival rates, and changes in biochemical and histologic parameters were compared among the groups. Five-minute heat shock preconditioning was not enough to Induce HSP72. However, livers in group GH5 expressed approximately the same amount of HSP72 as those in group VH15. The expression of HSP72 in group GH15 was stronger than that found in group VH15. The degree and location of HSP72 expression were not different between groups GH5 and VH15. Seven-day survival was significantly better in groups GH5 (16/16) and VH15 (15/16) than in group C (8/16) or VH5 (9/16). The recovery of adenosine triphosphate in liver tissue was faster, and the release of liver-related enzymes during reperfusion was lower in groups GH5 and VH15 than in group C or VH5. Administration of GGA before heat shock preconditioning augmented the induction of HSP72 by decreasing the threshold for triggering the stress response.

Topics: Alanine Transaminase; Animals; Anti-Ulcer Agents; Aspartate Aminotransferases; Diterpenes; Fluorescent Antibody Technique, Indirect; Heat-Shock Proteins; Heat-Shock Response; HSP72 Heat-Shock Proteins; Ischemic Preconditioning; L-Lactate Dehydrogenase; Liver; Liver Circulation; Male; Rats; Rats, Wistar; Reperfusion Injury; Survival Rate

Topics: Animals; Biomarkers; Diterpenes; Graft Survival; Heat-Shock Proteins; HSP72 Heat-Shock Proteins; Liver; Liver Transplantation; Male; Organ Preservation; Rats; Rats, Inbred BN; Reperfusion Injury; Temperature; Time Factors; Transplantation, Isogeneic

Topics: Administration, Oral; Animals; Anti-Ulcer Agents; Diterpenes; Graft Survival; Liver; Liver Transplantation; Male; Rats; Rats, Inbred BN; Reperfusion Injury; Transplantation, Isogeneic

The role of gastric mucus was evaluated in a rat model of gastric epithelial damage induced by local ischemia/reperfusion (I/R) stress. In this model, blood-to-lumen chromium 51-labeled ethylenediaminetetraacetic acid (51Cr-EDTA) clearance served as an index of injury. Tetraprenyl acetone (TPA; 100 mg, 200 mg/kg IP) was used to stimulate mucus production. Administration of TPA increased both the hexosamine content in gastric tissue and the amount of alcian blue-periodic acid Schiff (AB-PAS) stained mucus in the mucosa in a dose-dependent manner. Increases in 51Cr-EDTA clearance induced by I/R were significantly attenuated by TPA in a dose-dependent manner. N-acetyl-L-cysteine (NAC; 0.6%, 0.8%) was perfused into the gastric lumen to assess the effect of reduction in mucus on the injury induced by I/R. Although mean values of hexosamine content were increased by perfusion with NAC, AB-PAS-stained mucus in the mucosa was significantly decreased in a dose-dependent manner. Perfusion of NAC did not change basal 51Cr-EDTA clearance but significantly exacerbated the increase in clearance induced by I/R in a dose-dependent manner. These results indicate that gastric mucus protects the gastric mucosa against I/R stress in vivo.

Topics: Acetylcysteine; Alcian Blue; Animals; Chromium Radioisotopes; Diterpenes; Edetic Acid; Gastric Mucosa; Hexosamines; Ischemia; Male; Mucus; Periodic Acid-Schiff Reaction; Rats; Rats, Sprague-Dawley; Reperfusion Injury