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

A BAG-1-inhibitory peptide, GO-Pep, suppresses c-Raf activity in cancer

BAG-1 interacts with multiple partners, particularly with c-Raf, and promotes cancer cell survival. Hence, modulating the BAG-1-associated interactions with novel inhibitors could provide benefit for cancer therapy. Using HDX-MS, we first demonstrate the higher-order structure of BAG-1S and identify a potential "druggable" site on its BAG domain. An LC-MS/MS-coupled cell-free binding experiment is then used to map the BAG-1S:c-Raf interface, uncovering a 20-amino acid-length region of BAG-1S that is most likely to interact with c-Raf. Site-directed mutagenesis experiments reveal that K149 and L156 are hot spots for BAG-1S:c-Raf interaction, and their substitutions with alanine attenuate the survival of MCF-7 cells. We then show that a peptide derived from the BAG-1S-interacting c-Raf region hinders BAG domain-associated partners. The peptide, engineered with a cell-penetrating peptide motif, can penetrate cells, and it induces apoptosis in cancer cells. The anticancer activity of the peptide might lead to improved treatments for BAG-1-overexpressed and/or MAPK-driven tumors.

Pulmonary Flora-Derived Lipopolysaccharide Mediates Lung-Brain Axis through Activating Microglia Involved in Polystyrene Microplastic-Induced Cognitive Dysfunction

Microplastics (MPs) have been detected in the atmospheric and the human respiratory system, indicating that the respiratory tract is a significant exposure route for MPs. However, the effect of inhaled MPs on cognitive function has not been adequately studied. Here, a C57BL/6 J mouse model of inhalation exposure to polystyrene MPs (PS-MPs, 5 µm, 60 d) is established by intratracheal instillation. Interestingly, in vivo fluorescence imaging and transmission electron microscopy reveal that PS-MPs do not accumulate in the brain. However, behavioral experiments shows that cognitive function of mice is impaired, accompanied by histopathological damage of lung and brain tissue. Transcriptomic studies in hippocampal and lung tissue have demonstrated key neuroplasticity factors as well as cognitive deficits linked to lung injury, respectively. Mechanistically, the lung-brain axis plays a central role in PS-MPs-induced neurological damage, as demonstrated by pulmonary flora transplantation, lipopolysaccharide (LPS) intervention, and cell co-culture experiments. Together, inhalation of PS-MPs reduces cognitive function by altering the composition of pulmonary flora to produce more LPS and promoting M1 polarization of microglia, which provides new insights into the mechanism of nerve damage caused by inhaled MPs and also sheds new light on the prevention of neurotoxicity of environmental pollutants.

Cyanine dyes in the mitochondria-targeting photodynamic and photothermal therapy

Mitochondrial dysregulation plays a significant role in the carcinogenesis. On the other hand, its destabilization strongly represses the viability and metastatic potential of cancer cells. Photodynamic and photothermal therapies (PDT and PTT) target mitochondria effectively, providing innovative and non-invasive anticancer therapeutic modalities. Cyanine dyes, with strong mitochondrial selectivity, show significant potential in enhancing PDT and PTT. The potential and limitations of cyanine dyes for mitochondrial PDT and PTT are discussed, along with their applications in combination therapies, theranostic techniques, and optimal delivery systems. Additionally, novel approaches for sonodynamic therapy using photoactive cyanine dyes are presented, highlighting advances in cancer treatment.

Proteomic Analysis Revealed the Potential Role of MAGE-D2 in the Therapeutic Targeting of Triple-Negative Breast Cancer

Among all the molecular subtypes of breast cancer, triple-negative breast cancer (TNBC) is the most aggressive one. Currently, the clinical prognosis of TNBC is poor because there is still no effective therapeutic target. Here, we carried out a combined proteomic analysis involving bioinformatic analysis of the proteome database, label-free quantitative proteomics, and immunoprecipitation (IP) coupled with mass spectrometry (MS) to explore potential therapeutic targets for TNBC. The results of bioinformatic analysis showed an overexpression of MAGE-D2 (melanoma antigen family D2) in TNBC. In vivo and in vitro experiments revealed that MAGE-D2 overexpression could promote cell proliferation and metastasis. Furthermore, label-free quantitative proteomics revealed that MAGE-D2 acted as a cancer-promoting factor by activating the PI3K-AKT pathway. Moreover, the outcomes of IP-MS and cross-linking IP-MS demonstrated that MAGE-D2 could interact with Hsp70 and prevent Hsp70 degradation, but evidence for their direct interaction is still lacking. Nevertheless, MAGE-D2 is a potential therapeutic target for TNBC, and blocking MAGE-D2 may have important therapeutic implications.

Brain metabolism in Alzheimer's disease: biological mechanisms of exercise

Alzheimer's disease (AD) is a major subtype of neurodegenerative dementia caused by long-term interactions and accumulation of multiple adverse factors, accompanied by dysregulation of numerous intracellular signaling and molecular pathways in the brain. At the cellular and molecular levels, the neuronal cellular milieu of the AD brain exhibits metabolic abnormalities, compromised bioenergetics, impaired lipid metabolism, and reduced overall metabolic capacity, which lead to abnormal neural network activity and impaired neuroplasticity, thus accelerating the formation of extracellular senile plaques and intracellular neurofibrillary tangles. The current absence of effective pharmacological therapies for AD points to the urgent need to investigate the benefits of non-pharmacological approaches such as physical exercise. Despite the evidence that regular physical activity can improve metabolic dysfunction in the AD state, inhibit different pathophysiological molecular pathways associated with AD, influence the pathological process of AD, and exert a protective effect, there is no clear consensus on the specific biological and molecular mechanisms underlying the advantages of physical exercise. Here, we review how physical exercise improves crucial molecular pathways and biological processes associated with metabolic disorders in AD, including glucose metabolism, lipid metabolism, Aβ metabolism and transport, iron metabolism and tau pathology. How metabolic states influence brain health is also presented. A better knowledge on the neurophysiological mechanisms by which exercise improves AD metabolism can contribute to the development of novel drugs and improvement of non-pharmacological interventions.

Digital Microfluidics Supported Microproteomics for Quantitative Proteome Analysis of Single Caenorhabditis elegans Nematodes

Miniaturization of sample preparation, including omissible manual sample handling steps, is key for reproducible nanoproteomics, as material is often restricted to only hundreds of cells or single model organisms. Here, we demonstrate a highly sensitive digital microfluidics (DMF)-based sample preparation workflow making use of single-pot solid-phase enhanced sample preparation (SP3) in combination with high-field asymmetric-waveform ion mobility spectrometry (FAIMS), and fast and sensitive ion trap detection on an Orbitrap tribrid MS system. Compared to a manual in-tube SP3-supported sample preparation, the numbers of identified peptides and proteins were markedly increased, while lower standard deviations between replicates were observed. We repeatedly identified up to 5000 proteins from single nematodes. Moreover, label-free quantification of protein changes in single Caenorhabditis elegans treated with a heat stimulus yielded 45 differentially abundant proteins when compared to the untreated control, highlighting the potential of this technology for low-input proteomics studies. LC-MS data have been deposited to the ProteomeXchange Consortium with the data set identifier PXD033143.

Impact of Heat Stress on Bovine Sperm Quality and Competence

Global warming has negatively influenced animal production performance, in addition to animal well-being and welfare, consequently impairing the economic sustainability of the livestock industry. Heat stress impact on male fertility is complex and multifactorial, with the fertilizing ability of spermatozoa affected by several pathways. Among the most significative changes are the increase in and accumulation of reactive oxygen species (ROS) causing lipid peroxidation and motility impairment. The exposure of DNA during the cell division of spermatogenesis makes it vulnerable to both ROS and apoptotic enzymes, while the subsequent post-meiotic DNA condensation makes restoration impossible, harming later embryonic development. Mitochondria are also susceptible to the loss of membrane potential and electron leakage during oxidative phosphorylation, lowering their energy production capacity under heat stress. Although cells are equipped with defense mechanisms against heat stress, heat insults that are too intense lead to cell death. Heat shock proteins (HSP) belong to a thermostable and stress-induced protein family, which eliminate protein clusters and are essential to proteostasis under heat stress. This review focuses on effects of heat stress on sperm quality and on the mechanisms leading to defective sperm under heat stress.

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.

Bag-1L Protects against Cell Apoptosis in an In Vitro Model of Lung Ischemia-Reperfusion Injury through the C-Terminal "Bag" Domain

Bcl-2-associated athanogene 1 (Bag-1) is a multifunctional and antiapoptotic protein that binds to the antiapoptosis regulator Bcl-2 and promotes cell survival. To investigate the protective function of Bag-1, we examined the effects of Bag-1L, one isoform of Bag-1, in an in vitro cell culture model of lung ischemia-reperfusion injury (LIRI) generated by treatment of A549 cells with hypoxia/reoxygenation. Overexpression of full-length Bag-1L increased the viability of A549 cells and reduced cell apoptosis in response to 6 h of hypoxia/reoxygenation treatment. Furthermore, Bag-1L overexpression enhanced the heat shock protein 70 (HSP70) and Bcl-2 protein levels, increased the phosphorylation of AKT, decreased Bax and cleaved caspase-3 levels, and was able to overcome cell cycle arrest. These effects were not observed in A549 cells overexpressing a truncated form of Bag-1L lacking the "Bag domain," denoted Bag-1L△C. The "Bag domain" is the C-terminal 47 amino acids. Taken together, the results of this study suggest that Bag-1L overexpression can protect against oxidative stress and apoptosis in an in vitro LIRI model, with a dependence on the Bag domain.

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.

Heat Shock Protein HSP70 in Oxidative Stress in Apnea Patients

We studied the level of heat shock protein HSP70 under conditions of oxidative stress in 47 patients with apnea. The control group included 13 healthy subjects without verified apnea. Blood serum, plasma, and erythrocyte hemolysate were used to determine LPO and anti-oxidant protection components by spectrophotometrical and spectrofluorometrical methods. HSP70 was assayed by ELISA. A direct relationship was established between the intensity of oxidative stress and HSP70 expression in patients with apnea. Quantitative determination of HSP70 can be used as a molecular marker in the early diagnosis and prognosis of the development of various pathological conditions in hypoxia.

RP11-462C24.1 suppresses proliferation and invasion of colorectal carcinoma cells by regulating HSP70 through PI3K/AKT signaling pathway

Colorectal cancer (CRC) is the third leading cause of cancer-related death around the world. In this study, we investigated the roles of LncRNA RP11-462C24.1 in CRC. The expressions of RP11-462C24.1 in CRC tissues and cells were measured. Then, the effects of RP11-462C24.1 on CRC proliferation, cell cycle, apoptosis, and invasion were evaluated both in vivo and in vitro; Last, the underlying mechanisms of concerning the signaling pathway regulated by RP11-462C24.1 was determined. From the results, we found that RP11-462C24.1 was significantly decreased in CRC tumor tissues and the CRC cell lines, which were most significant in SW480 and HT-29 cell lines; moreover, transient overexpression of RP11-462C24.1 suppressed the growth and migration while promoted apoptosis of SW480 and HT-29 cells, while knockdown of RP11-462C24.1 has shown the opposite effects; RP11-462C24.1 may also inhibit the growth of CRC tumors in xenograft mice models; additionally, 70 kD heat shock proteins (HSP70) has been identified as one of the most significantly deferentially expressed genes by RNA-seq, and we further confirmed that RP11-462C24.1 may affect the growth and metathesis of CRC cells via regulating HSP70 and PI3K/AKT signaling pathway. In summary, these results indicated that RP11-462C24 may function as a tumor suppressor in the development of CRC.

A BAG's life: Every connection matters in cancer

The members of the BCL-2 associated athanogene (BAG) family participate in the regulation of a variety of interrelated physiological processes, such as autophagy, apoptosis, and protein homeostasis. Under normal circumstances, the six BAG members described in mammals (BAG1-6) principally assist the 70 kDa heat-shock protein (HSP70) in protein folding; however, their role as oncogenes is becoming increasingly evident. Deregulation of the BAG multigene family has been associated with cell transformation, tumor recurrence, and drug resistance. In addition to BAG overexpression, BAG members are also involved in many oncogenic protein-protein interactions (PPIs). As such, either the inhibition of overloading BAGs or of specific BAG-client protein interactions could have paramount therapeutic value. In this review, we will examine the role of each BAG family member in different malignancies, focusing on their modular structure, which enables interaction with a variety of proteins to exert their pro-tumorigenic role. Lastly, critical remarks on the unmet needs for proposing effective BAG inhibitors will be pointed out.

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.

Overexpressed Hsp70 alleviated formaldehyde-induced apoptosis partly via PI3K/Akt signaling pathway in human bronchial epithelial cells

Formaldehyde (FA) is a ubiquitous environmental pollutant, which can induce apoptosis in lung cell and is related to the pathogenesis of asthma, pneumonia, and chronic obstructive pulmonary disease. Heat shock protein 70 (Hsp70) is an ATP-dependent molecular chaperone and exhibits an anti-apoptosis ability in a variety of cells. Previous studies reported that the expression of Hsp70 was induced when organisms were exposed to FA. Whether Hsp70 plays a role in the FA-induced apoptosis and the involved cell signaling pathway remain largely unknown. In this study, human bronchial epithelial cells with overexpressed Hsp70 and the control were exposed to different concentrations of FA (0, 40, 80, and 160 μmol/L) for 24 hours. Apoptosis and the expression levels of PI3K, Akt, p-Akt, MEK, p-MEK, and GLI2 were detected by Annexin-APC/7AAD double-labeled flow cytometry and western blot. The results showed that overexpression of Hsp70 decreased the apoptosis induced by FA and alleviated the decline of PI3k and p-Akt significantly. Inhibitor (LY 294002, a specific inhibitor of PI3K-Akt) test result indicated that PI3K-Akt signaling pathway was involved in the inhibition of FA-induced apoptosis by Hsp70 overexpression and also active in the maintenance of GLI2 level. However, it also suggested that other signaling pathways activated by overexpressed Hsp70 participated in this process, which was needed to be elucidated in further research.

Protective effect of Schisandra chinensis lignans on hypoxia-induced PC12 cells and signal transduction

It is well-known that hypoxia induces neuronal injury; however, the mechanisms underlying this observed effect remain to be determined. Schisandra chinensis lignans (SCL). The aim of this study was thus to examine the ability of Schisandra chinensis lignans (SCL) to prevent hypoxia-induced neuronal injury using a human adrenal pheochromocytoma cell line (PC12). Exposure to hypoxia significantly reduced cell survival rate in cultured PC12 cells. However, pretreatment with SCL at 10, 20 or 40 μmol/L followed by hypoxia prevented loss of cellular viability. Flow cytometry demonstrated that the apoptotic rate in PC12 cells following hypoxia was significantly increased. Pretreatment with SCL 20 or 40 μmol/L in hypoxia-exposed cells resulted in significantly reduced apoptotic rates compared to hypoxia. Immunocytochemical staining showed that protein expression of p-Akt was significantly diminished by hypoxia. Following pre-treatment with different concentrations of SCL, PC12 cells were markedly stimulated as evidenced by elevated protein expression of p-Akt in a concentration-dependent manner. The expression of p-Akt protein in the presence of PI3K/Akt signaling pathway inhibitor LY294002 and SCL was not markedly changed indicating that signal transduction was affected by this Chinese herb. There were no significant differences in total Akt protein expression following hypoxia or pretreatment with SCL. Western blot demonstrated that expression levels of caspase-3 protein were significantly increased while expression levels of Bcl-2 protein were decreased in hypoxic cells. Pretreatment with SCL followed by hypoxia significantly lowered expression levels of caspase-3 protein accompanied by elevated expression levels of Bcl-2 protein in a concentration-dependent manner. After co-incubation with LY29004 and SCL, down-regulation of expression of caspase-3 protein and up-regulation of the expression of Bcl-2 protein noted with SCL alone were suppressed. Data suggest that the protective effect exerted by SCL in hypoxia-induced PC12 cell injury involves enhanced cell proliferation and inhibition of apoptosis mediated by activation of PI3K/Akt signaling pathway. The increased protein Akt phosphorylation expression levels resulted in consequent reduced downstream caspase-3 expression and enhanced Bcl-2 expression.