The Effects of Inorganic Arsenic On Apoptosis and Autophagy in Human Hepatic Sellate Cells

Endemic arsenism is a major disease concern in China, with arsenic poisoning and induced potential lesions key issues on a global level. The liver is the main target organ where arsenic is metabolized; chronic exposure to arsenic-induced liver fibrosis is also closely related to autophagy, however, the exact mechanisms are remain unclear. In this study, we explored the effects of NaAsO2 on apoptosis and autophagy in human hepatic stellate cells(HSC). We established a fibrosis model in the HSC line, LX-2 which was exposed to NaAsO2 for 24h, 48h, and 72h. Cells were then transfected using an autophagy double-labeled RFP-GFP-LC3 adenoviral plasmid. Laser confocal microscopy indicated significant infection efficiencies and autophagy in LX-2. Flow cytometry was also used to investigate the effects of different NaAsO2 doses on apoptosis. NaAsO2 treatment upregulated the expression of autophagic markers, including microtubule-associated protein light chain A/B(LC3), ubiquitin binding protein(SQSTM-1/P62), autophagy related genes(ATGs), recombinant human autophagy effector protein (Beclin-1), and B cell lymphoma-2(BCL-2), but downregulated mammalian target of rapamycin(mTOR). Also, α-smooth muscle actin(α-SMA) expression was significantly upregulated in all NaAsO2 groups. Furthermore, mTOR silencing via 3-methyladenine(3-MA) altered NaAsO2 induced autophagy, LC3, Beclin-1, and SQSTM-1/P62 expression were all upregulated in both NaAsO2 and 3-MA-iAs groups. Altogether, NaAsO2 induced HSC autophagy via apoptotic pathways. 3-MA inhibited LX-2 activity and reduced NaAsO2-induced autophagy which may inhibit fibrosis progression caused by this toxin.

MSC Pretreatment for Improved Transplantation Viability Results in Improved Ventricular Function in Infarcted Hearts

Many clinical studies utilizing MSCs (mesenchymal stem cells, mesenchymal stromal cells, or multipotential stromal cells) are underway in multiple clinical settings; however, the ideal approach to prepare these cells in vitro and to deliver them to injury sites in vivo with maximal effectiveness remains a challenge. Here, pretreating MSCs with agents that block the apoptotic pathways were compared with untreated MSCs. The treatment effects were evaluated in the myocardial infarct setting following direct injection, and physiological parameters were examined at 4 weeks post-infarct in a rat permanent ligation model. The prosurvival treated MSCs were detected in the hearts in greater abundance at 1 week and 4 weeks than the untreated MSCs. The untreated MSCs improved ejection fraction in infarcted hearts from 61% to 77% and the prosurvival treated MSCs further improved ejection fraction to 83% of normal. The untreated MSCs improved fractional shortening in the infarcted heart from 52% to 68%, and the prosurvival treated MSCs further improved fractional shortening to 77% of normal. Further improvements in survival of the MSC dose seems possible. Thus, pretreating MSCs for improved in vivo survival has implications for MSC-based cardiac therapies and in other indications where improved cell survival may improve effectiveness.

Apoptosis in Type 2 Diabetes: Can It Be Prevented? Hippo Pathway Prospects

Diabetes mellitus is a heterogeneous disease of complex etiology and pathogenesis. Hyperglycemia leads to many serious complications, but also directly initiates the process of β cell apoptosis. A potential strategy for the preservation of pancreatic β cells in diabetes may be to inhibit the implementation of pro-apoptotic pathways or to enhance the action of pancreatic protective factors. The Hippo signaling pathway is proposed and selected as a target to manipulate the activity of its core proteins in therapy-basic research. MST1 and LATS2, as major upstream signaling kinases of the Hippo pathway, are considered as target candidates for pharmacologically induced tissue regeneration and inhibition of apoptosis. Manipulating the activity of components of the Hippo pathway offers a wide range of possibilities, and thus is a potential tool in the treatment of diabetes and the regeneration of β cells. Therefore, it is important to fully understand the processes involved in apoptosis in diabetic states and completely characterize the role of this pathway in diabetes. Therapy consisting of slowing down or stopping the mechanisms of apoptosis may be an important direction of diabetes treatment in the future.

Accumulation of TERT in Mitochondria Shows Two Opposing Effects on Apoptosis

Telomerase reverse transcriptase (TERT) is a protein that catalyzes the reverse transcription of telomere elongation. TERT is also expected to play a noncanonical role beyond telomere lengthening since it localizes not only in the nucleus but also in mitochondria, where telomeres do not exist. Several studies have reported that mitochondrial TERT regulates apoptosis induced by oxidative stress. However, there remains controversy about whether mitochondrial TERT promotes or inhibits apoptosis, mainly due to the lack of information on changes in the TERT distribution in individual cells over time. Here we simultaneously detected apoptosis and TERT localization after oxidative stress in individual HeLa cells by live-cell tracking. This tracking revealed that the stress-induced accumulation of TERT in mitochondria resulted in apoptosis but that the accumulation positively correlated with the time until cell death. The results suggest a new model in which mitochondrial TERT has two opposing effects at different stages of apoptosis: it predetermines apoptosis at the first stage of cell-fate determination but also delays apoptosis at the second stage. Because these distinct effects respectively support both sides of the controversy regarding the role of mitochondrial TERT in apoptosis, our model integrates two opposing hypotheses. Furthermore, detailed statistical analysis of TERT mutations, which have been predicted to inhibit TERT transport to mitochondria, revealed that these mutations suppress apoptosis independent of the mitochondrial localization of TERT. Together, these results indicate that the non-canonical functions of TERT affect a wide range of apoptotic pathways.

Intrinsic apoptosis is evolutionary divergent among metazoans

Apoptosis is characterised by an analogous set of morphological features1 that depend on a proteolytic multigenic family, the caspases. Each apoptotic signalling pathway involves a specific initiator caspase, upstream of the pathway regulation, which finally converges to common executioner caspases. Intrinsic apoptosis, previously known as the mitochondrial apoptotic pathway, is often considered as ancestral and evolutionary conserved among animals. First identified in the nematode Caenorhabditis elegans, intrinsic apoptosis was next characterised in fruit fly Drosophila melanogaster and mammals. Intrinsic apoptosis depends on the key initiator caspase-9 (named Ced-3 and Dronc in Caenorhabditis and Drosophila, respectively), the activator Apaf-1 and the Bcl-2 multigenic family. Many functional studies have led to a deep characterisation of intrinsic apoptosis based on those classical models. Nevertheless, the biochemical role of mitochondria, the pivotal function of cytochrome c and the modality of caspases activation remain highly heterogeneous and hide profound molecular divergences among apoptotic pathways in animals. Independent of functional approaches, the phylogenetic history of the signal transduction actors, mostly the caspase family, is the Rosetta Stone to shed light on intrinsic apoptosis evolution. Here, after exhaustive research on CARD-caspases, we demonstrate by phylogenetic analysis that the caspase-9, the fundamental key of intrinsic apoptosis, is deuterostomes-specific, while it is the caspase-2 which is ancestral and common to bilaterians. Our analysis of Bcl-2 family and Apaf-1 confirm the high heterogeneity in apoptotic pathways elaboration in animals. Taken together, our results support convergent emergence of distinct intrinsic apoptotic pathways during metazoan evolution.

The role of Ubiquitination in Apoptosis and Necroptosis

Cell death pathways have evolved to maintain tissue homoeostasis and eliminate potentially harmful cells from within an organism, such as cells with damaged DNA that could lead to cancer. Apoptosis, known to eliminate cells in a predominantly non-inflammatory manner, is controlled by two main branches, the intrinsic and extrinsic apoptotic pathways. While the intrinsic pathway is regulated by the Bcl-2 family members, the extrinsic pathway is controlled by the Death receptors, members of the tumour necrosis factor (TNF) receptor superfamily. Death receptors can also activate a pro-inflammatory type of cell death, necroptosis, when Caspase-8 is inhibited. Apoptotic pathways are known to be tightly regulated by post-translational modifications, especially by ubiquitination. This review discusses research on ubiquitination-mediated regulation of apoptotic signalling. Additionally, the emerging importance of ubiquitination in regulating necroptosis is discussed.

Apoptosis Pathways Triggered by a Potent Antiproliferative Hybrid Chalcone on Human Melanoma Cells

The World Health Organization reported that approximately 324,000 new cases of melanoma skin cancer were diagnosed worldwide in 2020. The incidence of melanoma has been increasing over the past decades. Targeting apoptotic pathways is a potential therapeutic strategy in the transition to preclinical models and clinical trials. Some naturally occurring products and synthetic derivatives are apoptosis inducers and may represent a realistic option in the fight against the disease. Thus, chalcones have received considerable attention due to their potential cytotoxicity against cancer cells. We have previously reported a chalcone containing an indole and a pyridine heterocyclic rings and an α-bromoacryloylamido radical which displays potent antiproliferative activity against several tumor cell lines. In this study, we report that this chalcone is a potent apoptotic inducer for human melanoma cell lines SK-MEL-1 and MEL-HO. Cell death was associated with mitochondrial cytochrome c release and poly(ADP-ribose) polymerase cleavage and was prevented by a non-specific caspase inhibitor. Using SK-MEL-1 as a model, we found that the mechanism of cell death involves (i) the generation of reactive oxygen species, (ii) activation of the extrinsic and intrinsic apoptotic and mitogen-activated protein kinase pathways, (iii) upregulation of TRAIL, DR4 and DR5, (iv) downregulation of p21Cip1/WAF1 and, inhibition of the NF-κB pathway.

Hydrogen Sulfide Inhibits Inflammatory Pain and Enhances the Analgesic Properties of Delta Opioid Receptors

Chronic inflammatory pain is present in many pathologies and diminishes the patient’s quality of life. Moreover, most current treatments have a low efficacy and significant side effects. Recent studies demonstrate the analgesic properties of slow-releasing hydrogen sulfide (H2S) donors in animals with osteoarthritis or neuropathic pain, but their effects in inflammatory pain and related pathways are not completely understood. Several treatments potentiate the analgesic actions of δ-opioid receptor (DOR) agonists, but the role of H2S in modulating their effects and expression during inflammatory pain remains untested. In C57BL/6J male mice with inflammatory pain provoked by subplantar injection of complete Freund’s adjuvant, we evaluated: (1) the antiallodynic and antihyperalgesic effects of different doses of two slow-releasing H2S donors, i.e., diallyl disulfide (DADS) and phenyl isothiocyanate (P-ITC) and their mechanism of action; (2) the pain-relieving effects of DOR agonists co-administered with H2S donors; (3) the effects of DADS and P-ITC on the oxidative stress and molecular changes caused by peripheral inflammation. Results demonstrate that both H2S donors inhibited allodynia and hyperalgesia in a dose-dependent manner, potentiated the analgesic effects and expression of DOR, activated the antioxidant system, and reduced the nociceptive and apoptotic pathways. The data further demonstrate the possible participation of potassium channels and the Nrf2 transcription factor signaling pathway in the pain-relieving activities of DADS and P-ITC. This study suggests that the systemic administration of DADS and P-ITC and local application of DOR agonists in combination with slow-releasing H2S donors are two new strategies for the treatment of inflammatory pain.

Caffeine and Bronchopulmonary dysplasia ：Clinical Benefits and Its Mechanisms

Bronchopulmonary dysplasia (BPD) is a chronic respiratory disease caused by a combination of prenatal and postnatal factors that leads to the disruption of lung development and abnormal repair, this is a condition that is commonly seen in premature infants. With the improvement of treatment technology, the survival rate of very early preterm infants has increased significantly compared with before, and the incidence of severe BPD has decreased, however, the prevalence of BPD has not decreased. The overall prevalence of BPD is 45%.The prevention of prematurity, the systematic use of non-aggressive ventilator measures, the avoidance of supra-physiological oxygen exposure, and the administration of diuretics, caffeine and vitamin A have all been shown to lead to a significant reduction in the risk of BPD development. A growing number of clinical studies have shown that caffeine not only prevents apnea, but also reduces the incidence of BPD. We review the clinical value of caffeine in the treatment of BPD and its potential mechanisms of action, include anti-inflammatory, antioxidant, anti-fibrotic, anti-apoptotic pathways, and the regulation of angiogenesis. Our aim was to provide a new theoretical basis for the clinical treatment of BPD.