Hyperosmotic Shock Engages Two Positive Feedback Loops through Caspase-3-dependent Proteolysis of JNK1-2 and Bid

The Role of the Dysregulated JNK Signaling Pathway in the Pathogenesis of Human Diseases and Its Potential Therapeutic Strategies: A Comprehensive Review

JNK is named after c-Jun N-terminal kinase, as it is responsible for phosphorylating c-Jun. As a member of the mitogen-activated protein kinase (MAPK) family, JNK is also known as stress-activated kinase (SAPK) because it can be activated by extracellular stresses including growth factor, UV irradiation, and virus infection. Functionally, JNK regulates various cell behaviors such as cell differentiation, proliferation, survival, and metabolic reprogramming. Dysregulated JNK signaling contributes to several types of human diseases. Although the role of the JNK pathway in a single disease has been summarized in several previous publications, a comprehensive review of its role in multiple kinds of human diseases is missing. In this review, we begin by introducing the landmark discoveries, structures, tissue expression, and activation mechanisms of the JNK pathway. Next, we come to the focus of this work: a comprehensive summary of the role of the deregulated JNK pathway in multiple kinds of diseases. Beyond that, we also discuss the current strategies for targeting the JNK pathway for therapeutic intervention and summarize the application of JNK inhibitors as well as several challenges now faced. We expect that this review can provide a more comprehensive insight into the critical role of the JNK pathway in the pathogenesis of human diseases and hope that it also provides important clues for ameliorating disease conditions.

Exogenous Melatonin Ameliorates the Negative Effect of Osmotic Stress in Human and Bovine Ovarian Stromal Cells

Ovarian tissue cryopreservation transplantation (OTCT) is the most flexible option to preserve fertility in women and children with cancer. However, OTCT is associated with follicle loss and an accompanying short lifespan of the grafts. Cryopreservation-induced damage could be due to cryoprotective agent (CPA) toxicity and osmotic shock. Therefore, one way to avoid this damage is to maintain the cell volume within osmotic tolerance limits (OTLs). Here, we aimed to determine, for the first time, the OTLs of ovarian stromal cells (OSCs) and their relationship with reactive oxygen species (ROS) and mitochondrial respiratory chain activity (MRCA) of OSCs. We evaluated the effect of an optimal dose of melatonin on OTLs, viability, MRCA, ROS and total antioxidant capacity (TAC) of both human and bovine OSCs in plated and suspended cells. The OTLs of OSCs were between 200 and 375 mOsm/kg in bovine and between 150 and 500 mOsm/kg in human. Melatonin expands OTLs of OSCs. Furthermore, melatonin significantly reduced ROS and improved TAC, MRCA and viability. Due to the narrow osmotic window of OSCs, it is important to optimize the current protocols of OTCT to maintain enough alive stromal cells, which are necessary for follicle development and graft longevity. The addition of melatonin is a promising strategy for improved cryopreservation media.

Understanding MAPK Signaling Pathways in Apoptosis

MAPK (mitogen-activated protein kinase) signaling pathways regulate a variety of biological processes through multiple cellular mechanisms. In most of these processes, such as apoptosis, MAPKs have a dual role since they can act as activators or inhibitors, depending on the cell type and the stimulus. In this review, we present the main pro- and anti-apoptotic mechanisms regulated by MAPKs, as well as the crosstalk observed between some MAPKs. We also describe the basic signaling properties of MAPKs (ultrasensitivity, hysteresis, digital response), and the presence of different positive feedback loops in apoptosis. We provide a simple guide to predict MAPKs’ behavior, based on the intensity and duration of the stimulus. Finally, we consider the role of MAPKs in osmostress-induced apoptosis by using Xenopus oocytes as a cell model. As we will see, apoptosis is plagued with multiple positive feedback loops. We hope this review will help to understand how MAPK signaling pathways engage irreversible cellular decisions.

Endoplasmic Reticulum Stress Induces Macrophages to Produce IL-1β During Mycobacterium bovis Infection via a Positive Feedback Loop Between Mitochondrial Damage and Inflammasome Activation

Mycobacterium bovis, the causative agent of tuberculosis in cattle and humans, infects host macrophages and induces endoplasmic reticulum stress (ERS), mitochondrial damage, and interleukin (IL)-1β production. The relationship between these phenotypes is yet to be elucidated. In this study, we investigated the role of ERS in mitochondrial damage and IL-1β production in macrophages during infection with a virulent M. bovis strain. We found that ERS activates the inflammasome via NOD-like receptor family, pyrin domain-containing 3 (NLRP3)-caspase-8 and that IFN-inducible protein absent in melanoma 2 (AIM2) triggered mitochondrial damage. ERS increased reactive oxygen species (ROS), which promoted translocation of the inflammasome to the mitochondria. NLRP3, but not AIM2, was involved in the ERS-induced cleavage of caspase-8 and Bid, leading to mitochondrial damage, which was required for the production of mature IL-1β. Our data suggest that ERS induces macrophages to produce mature IL-1β during infection with virulent M. bovis through a positive feedback loop between mitochondrial damage and inflammasome activation. To the best of our knowledge, this is the first evidence of the involvement of ERS and mitochondrial damage in inflammasome activation during M. bovis infection.

MicroRNA-383 upregulation protects against propofol-induced hippocampal neuron apoptosis and cognitive impairment

Anesthesia-induced cognitive impairment is a recognized clinical phenomenon. The present study aimed to investigate the effect of microRNA-383 (miR-383) expression on propofol-induced learning and memory impairment. In total, 48 male Sprague-Dawley rats (weight, 250±10 g) were randomly divided into four groups (n=12 each): Control group, and three groups of rats that were anesthetized with propofol for 6 h and untreated (propofol model group), treated with a constructed lentivirus vector expressing miR-383 mimics (mimic + propofol group), or treated with miR-383 scramble (scramble + propofol group). The learning memory ability, hippocampal neuron apoptosis and expression of apoptosis-associated factors were detected using reverse transcription-quantitiative polymerase chain reaction and western blot analysis. Propofol treatment significantly reduced the relative mRNA and protein expression of miR-383, induced neuron apoptosis, upregulated the Bax/Bcl-2 ratio, downregulated the relative mRNA and protein expression levels of postsynaptic density protein 95 and cAMP-response element binding protein, and inactivated the phosphoinositide 3-kinase/protein kinase B signaling pathway. By contrast, miR-383 mimics significantly altered the propofol-induced dysregulation of the aforementioned factors. In conclusion, miR-383 mimic was able to repair propofol-induced cognitive impairment via protecting against hippocampal neuron apoptosis and dysregulation of related factors. The present study suggested that miR-383 may be used as a potential therapeutic target for the clinical treatment of cognitive impairment induced by propofol anesthesia.

EZH2-mediated suppression of lncRNA-LET promotes cell apoptosis and inhibits the proliferation of post-burn skin fibroblasts

Although the upregulation of enhancer of zeste homolog 2 (EZH2) expression and downregulation of long non-coding RNA (lncRNA) LET expression are known to be associated with cell apoptosis and proliferation, little is known about the interaction of EZH2 with lncRNA LET. The present study aimed to investigate the interaction of EZH2 and lncRNA LET, and the mechanism of human dermal fibroblast (HDF) proliferation and apoptosis. Tissue samples from 33 burn patients with second- and third-degree burns and 8 controls were collected. mRNA was extracted from the burn tissues for analysis. Isolated primary HDFs were treated with heat or transfected with LET overexpression vectors, and the cell functions and associated proteins in the HDFs were analyzed. Decreased lncRNA LET expression was detected in burn tissues compared with normal skin. Heat-treated HDFs exhibited a reduction in lncRNA LET expression and increase in EZH2 expression. LET gain-of-function experiments in primary HDFs revealed increases in cell proliferation, the proportion of cells in the S stage, and cyclin D1 and cyclin-dependent kinase 4 (CDK4) expression, and reductions in the percentage of apoptotic cells, the Bax/Bcl-2 ratio and caspase-3 expression. RNA immunoprecipitation and chromatin immunoprecipitation assays demonstrated the interaction of ZH2 with lncRNA LET, and of EZH2 with H3K27me3 in HDFs. Furthermore, a negative correlation between lncRNA LET and EZH2 expression was identified. It may be concluded that increased lncRNA-LET expression promoted cell proliferation and inhibited cell apoptosis via the cyclin D1-CDK4 and Bax/Bcl-2/caspase-3 signaling pathways, respectively. Furthermore, the inhibition of lncRNA LET may be regarded as an option for use in the healing of burns.

miR-183 Modulates Cell Apoptosis and Proliferation in Tongue Squamous Cell Carcinoma SCC25 Cell Line

This study was designed to investigate the role of miR-183 in modulating cell growth and apoptosis of tongue squamous cell carcinoma SCC25 cell line. Human squamous epithelial cell and squamous cell carcinoma cell line SCC25 was used, and miR-183 was inhibited. Cell growth, colony formation, and apoptotic rate, as well as the expression of caspase 3 and BCL-xL, were detected. Results showed that miR-183 was significantly overexpressed in the SCC25 cell line when compared with normal control. The miR-183 inhibitor reduced cell growth and colony formation, while the apoptosis percentage was significantly increased. The expression of activated caspase 3 and BCL-xL was obviously up- and downregulated in siRNA-transfected cells, respectively. In conclusion, miR-183 contributed to cell growth and proliferation, and suppressed cell apoptosis in SCC25 cells. Therefore, miR-183 might serve as a therapeutic target in tongue squamous cell carcinoma (TSCC).

The inhibitory effects of carnosic acid on cervical cancer cells growth by promoting apoptosis via ROS-regulated signaling pathway

Cervical cancer has been the fourth most common cancer killing many women across the world. Carnosic acid (CA), as a phenolic diterpene, has been suggested to against cancer, exerting protective effects associated with inflammatory cytokines. It is aimed to demonstrate the therapeutic role of carnosic acid against cervical cancer and indicate its underlying molecular mechanisms. 3-(4,5-dimethyl-2-thiazolyl)-2,5-diphenyl-2-H-tetrazolium bromide (MTT) was performed to assess the possible anti-proliferative effects of carnosic acid. And also, colony formation was used to further estimate carnosic acid's ability in suppressing cervical cancer cells proliferation. Flow cytometry assays were performed here to indicate the alterations of cervical cancer cells cycle and the development of apoptosis. Western blot assays and RT-PCR were also applied to clarify the apoptosis-associated signaling pathways affected by reactive oxygen species (ROS) generation. And immunofluorescence was used to detect ROS-positive cells. In vivo experiments, CaSki xenograft model samples of nude mice were involved to further elucidate the effects of carnosic acid. In our results, we found that carnosic acid exerted anti-tumor ability in vitro supported by up-regulation of apoptosis and ROS production in cervical cancer cells. Also, acceleration of ROS led to the phospharylation of (c-Jun N-terminal kinase (JNK) and its-related signals, as well as activation of Endoplasmic Reticulum (ER) stress, promoting the progression of apoptosis via stimulating Caspase3 expression. The development and growth of xenograft tumors in nude mice were found to be inhibited by the administration of carnosic acid for five weeks. And the suppressed role of carnosic acid in proliferation of cervical cancer cells and apoptosis of nude mice with tumor tissues were observed in our study. Taken together, our data indicated that carnosic acid resulted in apoptosis both in vitro and vivo experiments via promoting ROS and activating JNK signaling pathways in human cervical cancer cells, which supplied a potential therapy for the application of carnosic acid in clinical treatment.