Anti-hypoxia effect of adenovirus-mediated expression of heat shock protein 70 (HSP70) on primary cultured neurons

Cell-Permeable HSP70 Protects Neurons and Astrocytes Against Cell Death in the Rotenone-Induced and Familial Models of Parkinson's Disease

Heat shock protein 70 (HSP70) is activated under stress response. Its involvement in cell protection, including energy metabolism and quality control makes it a promising pharmacological target. A strategy to increase HSP70 levels inside the cells is the application of recombinant HSP70. However, cell permeability and functionality of these exogenously applied proteins inside the cells is still disputable. Here, using fluorescence- labeled HSP70, we have studied permeability and distribution of HSP70 inside primary neurons and astrocytes, and how exogenous HSP70 changes mitochondrial metabolism and mitophagy. We have found that exogenous recombinant HSP70 can penetrate the neurons and astrocytes and distributes in mitochondria, lysosomes and in lesser degree in the endoplasmic reticulum. HSP70 increases mitochondrial membrane potential in control neurons and astrocytes, and in fibroblasts of patients with familial Parkinson´s disease (PD) with PINK1 and LRRK2 mutations. Increased mitochondrial membrane potential was associated with higher mitochondrial ROS production and activation of mitophagy. Importantly, preincubation of the cells with HSP70 protected neurons and astrocytes against cell death in a toxic model of PD induced by rotenone, and in the PINK1 and LRRK2 PD human fibroblasts. Thus, exogenous recombinant HSP70 is cell permeable, and acts as endogenous HSP70 protecting cells in the case of toxic model and familial forms of Parkinson's Disease.

HSP70 inhibition suppressed glioma cell viability during hypoxia/reoxygenation by inhibiting the ERK1/2 and PI3K/AKT signaling pathways

Heat shock protein 70 (HSP70) can regulate astrocyte viability under hypoxic and ischemic conditions. However, the protective mechanism involved is not completely clear. This study aimed to investigate whether HSP70 protects U87 glioma cells against hypoxic damage via the extracellular signal-regulated kinases 1/2 (ERK1/2) and phosphoinositide 3-kinase/protein kinase B (PI3K/AKT) signaling pathways. Lentivirus-mediated HSP70-siRNA was used for HSP70 silencing. U87 glioma cells with lentiviral infection were exposed to hypoxia for 4, 8, 12, and 24 h, respectively, followed by a 24-h reoxygenation treatment. A Cell-Counting Kit-8 was then used to evaluate the viability of the U87 glioma cells. Reverse transcription quantitative polymerase chain reaction (RT-qPCR) and western blotting were performed to determine the mRNA and protein levels, respectively. The expression of HSP70, p-ERK1/2, p-AKT, and U87 cell viability were increased after 8 h of hypoxia/24 h of reoxygenation (P < 0.01). However, HSP70 silencing significantly decreased the U87 cell viability after the hypoxia/reoxygenation treatment (P < 0.01). The protein expressions of p-ERK1/2 and p-AKT also decreased in HSP70-silenced U87 cells (P < 0.01). In conclusion, HSP70 inhibition suppressed the viability of U87 glioma cells during hypoxia/reoxygenation (at least partially) by inhibiting the ERK1/2 and PI3K/AKT signaling pathways. This study may help to understand the molecular mechanisms underlying the progression and development of cerebral hypoxia-ischemia.

Mutation of the BAG-1 domain decreases its protective effect against hypoxia/reoxygenation by regulating HSP70 and the PI3K/AKT signalling pathway in SY-SH5Y cells

BCL-2-associated athanogene-1 (BAG-1) is a multifunctional protein that was first identified as a binding partner of BCL-2. Our previous results indicated that BAG-1 large (BAG-1L) overexpression significantly increases cell viability and decreases apoptosis by upregulating HSP70 and p-AKT in response to hypoxia/reoxygenation in SY-SH5Y cells. However, the functional domain of BAG-1L that exerts these protective effects against hypoxic damage has not been identified. In this study, we examined changes in HSP70 and p-AKT protein levels in SH-SY5Y cells with or without BAG-1L domain mutation after six hours of hypoxia/reoxygenation treatment. The BAG-1 domain mutant (BAG-1MUT) attenuated neuronal viability and proliferation while enhancing apoptosis after hypoxia/reoxygenation, which was achieved in part by inhibiting the HSP70 and p-AKT signalling pathways. This evidence illustrates that the BAG-1 domain plays a key role in protecting cells from hypoxia/reoxygenation injury.

Bag-1 Silence Sensitizes Non-Small Cell Lung Cancer Cells To Cisplatin Through Multiple Gene Pathways

Purpose

B-cell lymphoma-2 (Bcl-2) associated athanogene 1 (Bag-1) is a multifunctional protein, and Bag -1 overexpression is associated with progression, metastasis, and drug resistance in lung cancer. This study assessed the effects of Bag-1 siRNA on sensitization of cisplatin on non-small cell lung cancer (NSCLC) cells.

Material and methods

NSCLC A549 cell line was transfected with Bag-1 or negative control siRNA and then treated with cisplatin for cell viability, CCK-8, LDH, and flow cytometry assays. The Ca²⁺ levels were analyzed using Fluo-3/AM fluorescence staining, and the protein levels were assessed using Western blot analysis.

Results

Bag-1 siRNA significantly knocked down Bag-1 expression and inhibited cell invasion versus the negative control siRNA, while Bag-1 silence sensitized cisplatin to induce A549 cells to apoptosis by induction of cell cycle G1 arrest. At protein level, Bag-1 silence reduced the expression ratio of Bcl-2 to Bcl-2 associated X protein (Bax), downregulated activity of the PI3K/AKT and mitogen-activated protein kinase (MAPK) pathways, and potently upregulated the calcium signaling-mediated pathway.

Conclusion

This study demonstrated that Bag-1 silencing sensitized A549 to cisplatin to enhance A549 cell apoptosis by modified multiple gene pathways. Further study will evaluate the usefulness of Bag-1 siRNA as a potential targeting therapy for NSCLC.

BAG-1L Protects SH-SY5Y Neuroblastoma Cells Against Hypoxia/Re-oxygenation Through Up-Regulating HSP70 and Activating PI3K/AKT Signaling Pathway

BCL-2-associated athanogene-1(BAG-1) is a multifunctional and anti-apoptotic protein that was first identified as a binding partner of BCL-2. But the effects and mechanisms for BAG-1 against hypoxic damage is unclear up to now. Whether BAG-1 could protect the human brain against hypoxic damage through up-regulating 70 kDa heat shock proteins (HSP70) and PI3K/AKT pathway activation? In present study, we examined the changes of HSP70 and AKT and p-AKT protein level in SH-SY5Y cells with BAG-1L gene over-expression subjected to hypoxia/re-oxygenation injury. BAG-1L over-expression increased neuronal viability, and it reduced apoptosis of neurons after hypoxia/re-oxygenation for 8 h. BAG-1L over-expression enhanced the HSP70 protein levels and increased p-AKT/total AKT ratio after hypoxia/re-oxygenation for 8 h. These results suggest that BAG-1L over-expression protects against hypoxia/re-oxygenation injury, at least in part, by interacting with HSP70, and by accelerating the activation of PI3K/AKT pathways.

Serum Heat Shock Protein Levels and the Relationship of Heat Shock Proteins with Various Parameters in Chronic Obstructive Pulmonary Disease Patients

OBJECTIVES

Chronic Obstructive Pulmonary Disease (COPD) is accompanied by increased cellular stress and inflammation. Most of the Heat Shock Proteins (HSPs) have strong cytoprotective effects. The role of HSPs in COPD pathogenesis has not determined completely. We investigated the serum level of HSPs in COPD patients, smokers without COPD and healthy non-smoking controls. Also, we evaluated the relationship of HSPs with various parameters (inflammatory, oxidative, functional status, quality of life) in COPD patients.

MATERIAL AND METHODS

The levels of stress protein (HSP27, HSP70, HSP60, HSP90, CyPA), interleukin-6, C-reactive protein and malondialdehyde were measured in 16 healthy non-smoker, 14 smokers without COPD and 50 patients with stable COPD. Pulmonary function tests (PFT) and arterial blood gases parameters were measured. Health Related Quality of Life was evaluated and exercise capacity was measured with 6 minute walking test.

RESULTS

Only HSP27 levels was significantly higher in COPD patients when compared with both healthy non-smoker and smokers without COPD (for both, p< 0.001). There was a weak-moderate negative correlation between serum levels of HSP27 and PFT parameters and between HSP27 levels and PaO2. Serum levels of HSP27 showed a weak-moderate positive correlation with symptom, activity and total scores. Subjects evaluated only smokers without COPD and patients with COPD; HSP27 had an area under the curve (AUC) in the receiver operating characteristic (ROC) curve of 0.819 (0.702-0.935; 95% CI; p= 0.000).

CONCLUSION

Increased serum levels of HSP27 was found in COPD patients and our results showed sensitivity and specificity of serum HSP27 as diagnostic markers for COPD.

A role of Heat Shock Protein 70 in Photoreceptor Cell Death: Potential as a Novel Therapeutic Target in Retinal Degeneration

Retinal degenerative diseases (RDs) such as retinitis pigmentosa (RP) are a genetically heterogeneous group of disorders characterized by night blindness and peripheral vision loss, which caused by the dysfunction and death of photoreceptor cells. Although many causative gene mutations have been reported, the final common end stage is photoreceptor cell death. Unfortunately, no effective treatments or therapeutic agents have been discovered. Heat shock protein 70 (HSP70) is highly conserved and has antiapoptotic activities. A few reports have shown that HSP70 plays a role in RDs. Thus, we focused on the role of HSP70 in photoreceptor cell death. Using the N-methyl-N-nitrosourea (MNU)-induced photoreceptor cell death model in mice, we could examine two stages of the novel cell death mechanism; the early stage, including HSP70 cleavage through protein carbonylation by production of reactive oxygen species, lipid peroxidation and Ca(2+) influx/calpain activation, and the late stage of cathepsin and/or caspase activation. The upregulation of intact HSP70 expression by its inducer is likely to protect photoreceptor cells. In this review, we focus on the role of HSP70 and the novel cell death signaling process in RDs. We also describe candidate therapeutic agents for RDs.

Purification of polysaccharides from Cordyceps militaris and their anti‑hypoxic effect

Acute mountain sickness, one of the most common altitude diseases, causes lung and brain injury. The present study aimed to investigate the anti‑hypoxic effect of purified polysaccharides extracted from Cordyceps militaris. The aqueous extract of Cordyceps militaris was purified progressively through a DEAE‑52 cellulose anion exchange column and a Sepharose G‑100 column. The fraction CMN1, with a molecular weight of 37842 Da, was the main fraction obtained and its chemical composition and structural characteristics were determined. CMN1 was found to have a monosaccharide composition of L‑rhamnose, L‑arabinose, D‑mannose, D‑galactose. The backbone of CMN1 comprised (1→2) and (1→3) linkages, with branched (1→6) and (1→4) linkages. The anti‑hypoxic effects of CMN1 were determined using a sodium nitrite toxicosis test, acute cerebral ischemic/hypoxic test and normobarie hypoxia test. CMN1 (0.5 g/kg) possessed a similar anti‑hypoxic effect to rhodiola oral liquid. Overall, the Cordyceps militaris polysaccharide, CMN1, was identified as an effective agent against hypoxia.

Non-pharmaceutical therapies for stroke: mechanisms and clinical implications

Stroke is deemed a worldwide leading cause of neurological disability and death, however, there is currently no promising pharmacotherapy for acute ischemic stroke aside from intravenous or intra-arterial thrombolysis. Yet because of the narrow therapeutic time window involved, thrombolytic application is very restricted in clinical settings. Accumulating data suggest that non-pharmaceutical therapies for stroke might provide new opportunities for stroke treatment. Here we review recent research progress in the mechanisms and clinical implications of non-pharmaceutical therapies, mainly including neuroprotective approaches such as hypothermia, ischemic/hypoxic conditioning, acupuncture, medical gases and transcranial laser therapy. In addition, we briefly summarize mechanical endovascular recanalization devices and recovery devices for the treatment of the chronic phase of stroke and discuss the relative merits of these devices.