Bax Activation Research Articles

Effect of Interval Training and Curcumin on BAX, Bcl-2, and Caspase-3 Enzyme Activity in Rats

Background: Apoptosis is a type of programmed cell death in extracellular organisms. High-intensity interval training and curcumin can make some changes in this process. Objectives: This study aimed to investigate the role of intense interval training with curcumin supplementation on BAX and Bcl-2 proteins and caspase-3 enzyme activity in rats. Methods: In this study, 48 elderly rats were randomly divided into four groups: (1) control, (2) training, (3) curcumin, and (4) training + curcumin. Then, high-intensity interval training group rats ran on the treadmill for eight weeks, five sessions per week, for 30 - 50 min, and curcumin was fed to the supplement group at 25 mg/kg of body weight three times per week for eight weeks. Gene expression levels of BAX and Bcl-2 and myocardial caspase enzyme were measured in the heart tissue. The Shapiro-Wilk test, one-way ANOVA, and Tukey test were used for data analysis. Results: Curcumin consumption and intense interval training increased the expression of BAX (P = 0.001), Bcl-2 (P = 0.002), and caspase (P = 0.001). Besides, BAX, Bcl-2, and caspase genes expression significantly changed in the groups compared to the control group. The ratio of BAX to Bcl-2 in the curcumin group and interval training was significantly lower than the other groups. The Tukey post hoc test confirmed a significant difference between the groups and the control group. Conclusions: High-intensity interval training did not reduce BAX protein, but the training and curcumin supplementation increased Bcl-2 protein expression and neutralized the BAX effect. Curcumin supplementation combined with intense interval training resulted in synergy and reduced cell programming mortality.

SK1 Inhibitor RB005 Induces Apoptosis in Colorectal Cancer Cells through SK1 Inhibition Dependent and Independent Pathway.

Colorectal cancer (CRC) is the fourth leading cause of cancer- related death globally, with a high incidence rate in economically fast-growing countries. Sphingosine- 1-phosphate (S1P) is a bioactive lipid mediator that plays critical roles in cancer cell proliferation, migration, and angiogenesis converted by the isoforms of sphingosine kinase (SK1 and SK2). SK1 is highly expressed in colorectal cancer; its inhibitors suppress the formation of S1P and increase ceramide levels having a pro-apoptotic function. RB005 is a selective SK1 inhibitor and a structural analog of PP2A activator FTY720. The purpose of this study is to test whether RB005, an SK1 inhibitor, can be used as an anticancer agent by inhibiting the growth of colon cancer cells. We performed MTT and colony-forming assay using colon cancer cell lines HT29 and HCT116 cells to examine the cell toxicity effect of RB005. To determine whether apoptosis of RB005 in colon cancer cell line is due to SK1 inhibition or other mechanisms due to its structural similarity with FTY720, we conducted LC/MS, siRNA knockdown, and PP2A activity experiments. RB005 notably inhibited CRC cell growth and proliferation compared to PF543 and ABC294640 by inducing the mitochondria-mediated intrinsic apoptotic pathway. Apoptotic cell death is caused by increased mitochondrial permeability Initiated by the activation of pro-apoptotic protein BAX, increased ceramides, and activation of PP2A. Also, RB005 treatment in HT29 cells did not change the expression level of SK1, but strikingly decreased SK1 activity and S1P levels. All these events of cell death and apoptosis were less effective when SK1 was knocked down by siRNA. This result indicates that RB005 shows the in-vitro anti-CRC effect by inhibiting SK1 activity and PP2A activation, increasing proapoptotic ceramide levels following the activation of the intrinsic apoptotic pathway.

Design, Synthesis, In Vitro Biological Activity Evaluation and Stabilized Nanostructured Lipid Carrier Formulation of Newly Synthesized Schiff Bases-Based TMP Moieties.

A series of novel Schiff bases-based TMP moieties have been designed and synthesized as potential anticancer agents. The target Schiff bases were screened for their cytotoxic activity against the MDA-MB-231 breast cancer cell line. Most of the tested molecules revealed good cytotoxic activity, especially compounds 4h, 4j and 5d. Being the most potent, compound 4h showed good tubulin polymerization inhibition activity as revealed by immunofluorescence analysis and ELISA assay. Additionally, compound 4h was screened for cell cycle disturbance and apoptosis induction. Pre-G1 apoptosis and cell growth halt at the G2/M phase were discovered to be caused by it. Moreover, compound 4h induced apoptosis via p53 and Bax activation, as well as reduced the level of Bcl-2. Additionally, the most potent compound 4h was lodged on nanostructured lipid carriers (NLCs). 23 full factorial design was involved to govern the influence of the fabrication variables on the in vitro characters of the casted NLCs. F3 was picked as the optimum formula exhibiting dominant desirability value 0.805, EE% 95.6 ± 2.4, PS 222.4 ±18.7, PDI 0.23 ± 0.05 and ZP −39.2 ± 3.9 Mv. Furthermore, F3 affirmed improved solubility and release over the drug suspension. In the comparative cytotoxic activity, F3 was capable of diminishing the IC50 by around 2.15 times for pure 4h, while nearly close to the IC50 of the reference drug. Thus, NLCs could be a potential platform for boosted antitumor activity.

Curcumin-Encapsulated Chitosan-Coated Nanoformulation as an Improved Otoprotective Strategy for Ototoxic Hearing Loss.

Overexpression of apoptotic factors in the inner ear is generally proven to induce ototoxicity. This has aroused research interest in various antiapoptotic drugs, the most representative of which is curcumin (CUR). In this study, two nanoformulations of CUR were developed with sustained-release behavior to improve their protective effects against ototoxic hearing loss (HL), which were the nanoparticles of CUR-loaded poly(lactic acid-glycolic acid) (CUR-PLGA NPs) and CUR-loaded chitosan-coated PLGA NPs (CUR-CS/PLGA NPs). The obtained results revealed that both CUR-NPs provided otoprotection in vitro and in vivo, and their effective doses in guinea pigs were much less than that of dexamethasone, which was clinically used to treat HL. Moreover, relative to CUR and CUR-PLGA NPs, CUR-CS/PLGA NPs exhibited the highest accumulation in HEI-OC1 cells and guinea pigs' cochlea. In pharmacodynamic experiments, the optimal administration timing was investigated, and CUR-CS/PLGA NPs showed sustained efficacy and the best hearing improvement at all tested sound frequencies. Lastly, the protective effect of CUR nanoformulations was further validated via inhibition of Caspase-3 and Bax activation, thereby reducing the concentration of reactive oxygen species and protecting mitochondrial integrity in hair cells. Collectively, CUR-CS/PLGA NPs demonstrated potent and lasting effects against ototoxic HL, making our novel formulation a promising candidate for the alleviation of sensorineural HL.

Modeling the role of cyclin C in connecting stress‐induced mitochondrial fission to apoptosis

For normal cell function, exogenous signals must be correctly interpreted, and the proper response executed. The mitochondria are key regulatory nodes of cellular fate. For example, mitochondria undergo fission and fusion cycles depending on the energetic needs of the cell. Additionally, regulated cell death pathways also function at the mitochondria. Cyclin C is a transcriptional regulator of stress response and growth control genes. Following stress, a portion of cyclin C translocates to the cytoplasm, where it interacts with both the mitochondrial fission and apoptotic machinery. Based on these findings, we hypothesize that cyclin C represents a key mediator linking transcription to mitochondrial fission and intrinsic regulated cell death. Members of the cyclin protein family typically contain two conserved cyclin box domains each composed of five alpha‐helices. The N‐terminal cyclin box domain, CB1, is responsible for binding cyclin‐dependent kinases (Cdks), while the C‐terminal cyclin box, CB2, typically facilitates correct protein folding. For cyclin C, CB1 and CB2 mediate protein‐protein interactions with regards to transcriptional regulation (Cdk8) and mitochondrial fission (Drp1), respectively. Pull down assays show that pro‐apoptotic protein Bax interacts in a direct manner with cyclin C and this interaction is required for Bax activation and ultimately efficient intrinsic regulated cell death. Using the docking simulator ClusPro, cyclin C and Bax yielded consistent protein‐protein interaction sites within amino acids 160‐170 of cyclin C. Important residues in order of decreasing frequency include: Q161, D165, E169, Y162, Q164, and D170. Six sets of docking simulations yielded identical results, using multiple cyclin C and Bax protein data bank file combinations as a means of accounting for potential differences in the starting .pdb files. Inspection of this region in cyclin C shows a high degree of homology to the BH2 domain found in members of the Bcl‐2 protein family, such as Bax, Bak, and Bcl2. These data suggest that cyclin C possesses a BH2 domain directing Bax interaction and intrinsic regulated cell death. Interestingly, CB2 is also responsible for binding the fission protein Drp1. However preliminary modeling data suggest that this interaction is mediated by the latter half of CB2. Prior work also has demonstrated that while the BH2 domain is required for Bax binding, it is not required for interaction with Drp1. Co‐immunoprecipitation assays show Drp1 is required for cyclin C‐Bax interaction, suggesting a role for the interaction of all three proteins. Taken together, these results suggest a model that cyclin C physically bridges the fission and apoptotic machinery allowing the cell to coordinate mitochondrial dynamics with programmed cell death pathways.

Primary acute lymphoblastic leukemia cells are susceptible to microtubule depolymerization in G1 and M phases through distinct cell death pathways

Microtubule targeting agents (MTAs) are widely used cancer chemotherapeutics which conventionally exert their effects during mitosis, leading to mitotic or postmitotic death. However, accumulating evidence suggests that MTAs can also generate death signals during interphase, which may represent a key mechanism in the clinical setting. We reported previously that vincristine and other microtubule destabilizers induce death not only in M phase but also in G1 phase in primary acute lymphoblastic leukemia cells. Here, we sought to investigate and compare the pathways responsible for phase-specific cell death. Primary acute lymphoblastic leukemia cells were subjected to centrifugal elutriation, and cell populations enriched in G1 phase (97%) or G2/M phases (80%) were obtained and treated with vincristine. We found death of M phase cells was associated with established features of mitochondrial-mediated apoptosis, including Bax activation, loss of mitochondrial transmembrane potential, caspase-3 activation, and nucleosomal DNA fragmentation. In contrast, death of G1 phase cells was not associated with pronounced Bax or caspase-3 activation but was associated with loss of mitochondrial transmembrane potential, parylation, nuclear translocation of apoptosis-inducing factor and endonuclease G, and supra-nucleosomal DNA fragmentation, which was enhanced by inhibition of autophagy. The results indicate that microtubule depolymerization induces distinct cell death pathways depending on during which phase of the cell cycle microtubule perturbation occurs. The observation that a specific type of drug can enter a single cell type and induce two different modes of death is novel and intriguing. These findings provide a basis for advancing knowledge of clinical mechanisms of MTAs.

Melatonin treatment improves human umbilical cord mesenchymal stem cell therapy in a mouse model of type II diabetes mellitus via the PI3K/AKT signaling pathway

BackgroundMesenchymal stem cells (MSCs) are promising candidates for tissue regeneration and disease treatment. However, long-term in vitro passaging leads to stemness loss of MSCs, resulting in failure of MSC therapy. This study investigated whether the combination of melatonin and human umbilical cord mesenchymal stem cells (hUC-MSCs) was superior to hUC-MSCs alone in ameliorating high-fat diet and streptozocin (STZ)-induced type II diabetes mellitus (T2DM) in a mouse model.MethodsMice were divided into four groups: normal control (NC) group; T2DM group; hUC-MSCs treatment alone (UCMSC) group and pretreatment of hUC-MSCs with melatonin (UCMSC/Mel) group.ResultsRNA sequence analysis showed that certain pathways, including the signaling pathway involved in the regulation of cell proliferation signaling pathway, were regulated by melatonin. The blood glucose levels of the mice in the UCMSC and UCMSC/Mel treatment groups were significantly reduced compared with the T2DM group without treatment (P < 0.05). Furthermore, hUC-MSCs enhance the key factor in the activation of the PI3K/Akt pathway in T2DM mouse hepatocytes.ConclusionThe pretreatment of hUC-MSCs with melatonin partly boosted cell efficiency and thereby alleviated impaired glycemic control and insulin resistance. This study provides a practical strategy to improve the application of hUC-MSCs in diabetes mellitus and cytotherapy.Graphical abstractOverview of the PI3K/AKT signaling pathway. (A) Underlying mechanism of UCMSC/Mel inhibition of hyperglycemia and insulin resistance T2DM mice via regulation of PI3K/AKT pathway. hUC-MSCs stimulates glucose uptake and improves insulin action thus should inhibition the clinical signs of T2DM, through activation of the p-PI3K/Akt signaling pathway and then regulates glucose transport through activating AS160. UCMSC/Mel increases p53-dependent expression of BCL2, and inhibit BAX and Capase3 protein activation. Leading to the decrease in apoptosis. (B) Melatonin modulated PI3K/AKT signaling pathway. Melatonin activated PI3K/AKT response pathway through binding to MT1and MT2 receptor. Leading to the increase in hUC-MSCs proliferation, migration and differentiation. → (Direct stimulatory modification); ┴ ( Direct Inhibitory modification); → ┤ (Multistep inhibitory modification); ↑ (Up regulate); ↓ (Down regulate); PI3K (Phosphoinositide 3-Kinase); AKT ( protein kinase B); PDK1 (Phosphoinositide-dependent protein kinase 1); IR, insulin receptor; GLUT4 ( glucose transporter type 4); ROS (reactive oxygen species); BCL-2 (B-cell lymphoma-2); PDK1 (phosphoinositide-dependent kinase 1) BAX (B-cell lymphoma-2-associated X protein); PCNA (Proliferating cell nuclear antigen); Cell cycle-associated proteins (KI67, cyclin A, cyclin E)

Transcriptional Activity of Some Genes Involved in Apoptosis in Patients with Vulvar Lichen Sclerosus.

Lichen sclerosus of the vulva is a common, but poorly studied disease. We assessed the level of transcriptional activity of APAF1, BAX, BCL2, BIRC5, CCND1, DAPK1, MCL1, and MYC genes encoding products that control apoptosis in the samples of tissues affected by vulvar lichen sclerosus and adjacent control tissues (n=24). Analysis of transcriptional activity was performed by real-time PCR using specific primers and SYBR Green intercalating dye. After the total group was divided by the presence of the concomitant gynecological diseases, a significant increase in the transcriptional activity of the CCND1 gene was revealed in patients with concomitant uterine fibroids. This may indicate the possible role of the activation of mitosis during tumor initiation.

Acetic acid triggers cytochrome c release in yeast heterologously expressing human Bax.

Proteins of the Bcl-2 protein family, including pro-apoptotic Bax and anti-apoptotic Bcl-xL, are critical for mitochondrial-mediated apoptosis regulation. Since yeast lacks obvious orthologs of Bcl-2 family members, heterologous expression of these proteins has been used to investigate their molecular and functional aspects. Active Bax is involved in the formation of mitochondrial outer membrane pores, through which cytochromec (cyt c) is released, triggering a cascade of downstream apoptotic events. However, when in its inactive form, Bax is largely cytosolic or weakly bound to mitochondria. Given the central role of Bax in apoptosis, studies aiming to understand its regulation are of paramount importance towards its exploitation as a therapeutic target. So far, studies taking advantage of heterologous expression of human Bax in yeast to unveil regulation of Bax activation have relied on the use of artificial mutated or mitochondrial tagged Bax for its activation, rather than the wild type Bax (Bax α). Here, we found that cell death could be triggered in yeast cells heterologoulsy expressing Bax α with concentrations of acetic acid that are not lethal to wild type cells. This was associated with Bax mitochondrial translocation and cytcrelease, closely resembling the natural Bax function in the cellular context. This regulated cell death process wasreverted by co-expression with Bcl-xL, but not with Bcl-xLΔC, and in the absence of Rim11p, the yeast ortholog of mammalian GSK3β. This novel system mimics human Bax α regulation by GSK3β and can therefore be used as a platform to uncover novel Bax regulators and explore its therapeutic modulation.

Mitigation of liver fibrosis via hepatic stellate cells mitochondrial apoptosis induced by metformin

Liver fibrosis, a disease characterized by the excessive accumulation of extracellular matrix originating from activated hepatic stellate cells (HSCs), is a common pathological response to chronic liver injury resulting from a variety of insults. However, drugs that effectively block the activation of HSCs have still not been adequately investigated. This study demonstrates that metformin decreased the number of activated-HSCs through induction of apoptosis, but did not impact numbers of hepatocytes. Metformin upregulated BAX activation with facilitation of BIM, BAD and PUMA; downregulated Bcl-2 and Bcl-xl, but did not affect Mcl-1. Additionally, metformin induced cytochrome c release from mitochondria into the cytoplasm, directly triggering caspase-9-mediated mitochondrial apoptosis. The decline in mitochondrial membrane potential (ΔΨm) and deposition of superoxide in mitochondria accelerated the destruction of the integrity of mitochondrial membrane. Moreover, we verified the therapeutic effect of metformin in our mouse model of liver fibrosis associated with nonalcoholic steatohepatitis (NASH) in which hepatic function, NASH lesions and fibrosis were improved by metformin. In conclusion, this study indicated that metformin has significant therapeutic value in NASH-derived liver fibrosis by inducing apoptosis in HSCs, but does not affect the proliferation of hepatocytes.

Glycerophosphoinositol Promotes Apoptosis of Chronic Lymphocytic Leukemia Cells by Enhancing Bax Expression and Activation.

An imbalance in the expression of pro- and anti-apoptotic members of the Bcl-2 family of apoptosis-regulating proteins is one of the main biological features of CLL, highlighting these proteins as therapeutic targets for treatment of this malignancy. Indeed, the Bcl-2 inhibitor Venetoclax is currently used for both first-line treatment and treatment of relapsed or refractory CLL. An alternative avenue is the transcriptional modulation of Bcl-2 family members to tilt their balance towards apoptosis. Glycerophosphoinositol (GroPIns) is a biomolecule generated from membrane phosphoinositides by the enzymes phospholipase A2 and lysolipase that pleiotropically affects key cellular functions. Mass-spectrometry analysis of GroPIns interactors recently highlighted the ability of GroPIns to bind to the non-receptor tyrosine phosphatase SHP-1, a known promoter of Bax expression, suggesting that GroPIns might correct the Bax expression defect in CLL cells, thereby promoting their apoptotic demise. To test this hypothesis, we cultured CLL cells in the presence of GroPIns, alone or in combination with drugs commonly used for treatment of CLL. We found that GroPIns alone increases Bax expression and apoptosis in CLL cells and enhances the pro-apoptotic activity of drugs used for CLL treatment in a SHP-1 dependent manner. Interestingly, among GroPIns interactors we found Bax itself. Short-term treatments of CLL cells with GroPIns induce Bax activation and translocation to the mitochondria. Moreover, GroPIns enhances the pro-apoptotic activity of Venetoclax and Fludarabine in CLL cells. These data provide evidence that GroPIns exploits two different pathways converging on Bax to promote apoptosis of leukemic cells and pave the way to new studies aimed at testing GroPIns in combination therapies for the treatment of CLL.

Co-targeting of BAX and BCL-XL proteins broadly overcomes resistance to apoptosis in cancer

Deregulation of the BCL-2 family interaction network ensures cancer resistance to apoptosis and is a major challenge to current treatments. Cancer cells commonly evade apoptosis through upregulation of the BCL-2 anti-apoptotic proteins; however, more resistant cancers also downregulate or inactivate pro-apoptotic proteins to suppress apoptosis. Here, we find that apoptosis resistance in a diverse panel of solid and hematological malignancies is mediated by both overexpression of BCL-XL and an unprimed apoptotic state, limiting direct and indirect activation mechanisms of pro-apoptotic BAX. Both survival mechanisms can be overcome by the combination of an orally bioavailable BAX activator, BTSA1.2 with Navitoclax. The combination demonstrates synergistic efficacy in apoptosis-resistant cancer cells, xenografts, and patient-derived tumors while sparing healthy tissues. Additionally, functional assays and genomic markers are identified to predict sensitive tumors to the combination treatment. These findings advance the understanding of apoptosis resistance mechanisms and demonstrate a novel therapeutic strategy for cancer treatment.

A taste of the early steps in BAX activation with FLAMBE

The activation of BAX through intricate intramolecular changes is critical for apoptosis. In this issue of Cell Reports Methods, Gelles et al. report engineering FLAMBE, an elegant fluorescence polarization ligand assay for monitoring the early activation of monomeric BAX via real-time release of a peptide probe, expanding the repertoire of BAX activation assays to the single-molecule level.

A kinetic fluorescence polarization ligand assay for monitoring BAX early activation

SummaryDevelopmental, homeostatic, and pharmacological pro-apoptotic signals converge by activating the BCL-2 family member BAX. Studies investigating molecular regulation of BAX are commonly limited to methodologies measuring endpoint phenotypes and do not assess activation of monomeric BAX. Here, we present FLAMBE, a fluorescence polarization ligand assay for monitoring BAX early activation, that measures activation-induced release of a peptide probe in real time. Using complementary parallel and tandem biochemical techniques, we validate, corroborate, and apply FLAMBE to a contemporary repertoire of BAX modulators, characterizing their contributions within the early steps of BAX activation. Additionally, we use FLAMBE to reveal that historically “dead” BAX mutants remain responsive to activation as quasi-functional monomers. We also identify data metrics for comparative analyses and demonstrate that FLAMBE data align with downstream functional observations. Collectively, FLAMBE advances our understanding of BAX activation and fills a methodological void for studying BAX with broad applications in cell biology and therapeutic development.

Protective role of crocin against sepsis-induced injury in the liver, kidney and lungs via inhibition of p38 MAPK/NF-κB and Bax/Bcl-2 signalling pathways

Context Crocin has been reported to have multiple bioactivities. However, the effect of crocin administration on caecal ligation and puncture (CLP)-induced sepsis remains unknown. Objective We investigated the effects of crocin on CLP-induced sepsis in mice and the underlying mechanism of action. Materials and methods Five experimental groups (n = 10) of BALB/c mice were used: control, CLP (normal saline) and CLP + crocin (50, 100 and 250 mg/kg, 30 min prior to CLP). Mice were sacrificed 24 h after CLP. Liver, kidney and lung histopathology, indicator levels, apoptotic status, pro-inflammatory cytokines and relative protein levels were evaluated. Results Compared to the CLP group, crocin treatment significantly increased the survival rate (70%, 80%, 90% vs. 30%). Crocin groups exhibited protection against liver, kidney and lung damage with mild-to-moderate morphological changes and lower indicator levels: liver (2.80 ± 0.45, 2.60 ± 0.55, 1.60 ± 0.55 vs. 5.60 ± 0.55), kidney (3.00 ± 0.71, 2.60 ± 0.55, 1.40 ± 0.55 vs. 6.20 ± 0.84) and lungs (8.00 ± 1.59, 6.80 ± 1.64, 2.80 ± 0.84 vs. 14.80 ± 1.79). The proinflammatory cytokines (IL-1β, TNF-α, IL-6 and IL-10 levels in the crocin groups) were distinctly lower and the apoptotic index showed a significant decrease. Crocin administration significantly suppressed p38 MAPK phosphorylation and inhibited NF-κB/IκBα and Bcl-2/Bax activation. Discussion and conclusions Pre-treatment with crocin confers protective effects against CLP-induced liver, kidney and lung injury, implying it to be a potential therapeutic agent.

Employing CRISPR-Cas9 to Generate CD133 Synthetic Lethal Melanoma Stem Cells.

Malignant melanoma is a lethal skin cancer containing melanoma-initiating cells (MIC) implicated in tumorigenesis, invasion, and drug resistance, and is characterized by the elevated expression of stem cell markers, including CD133. The siRNA knockdown of CD133 enhances apoptosis induced by the MEK inhibitor trametinib in melanoma cells. This study investigates the underlying mechanisms of CD133’s anti-apoptotic activity in patient-derived BAKP and POT cells, harboring difficult-to-treat NRASQ61K and NRASQ61R drivers, after CRISPR-Cas9 CD133 knockout or Dox-inducible expression of CD133. MACS-sorted CD133(+) BAKP cells were conditionally reprogrammed to derive BAKR cells with sustained CD133 expression and MIC features. Compared to BAKP, CD133(+) BAKR exhibit increased cell survival and reduced apoptosis in response to trametinib or the chemotherapeutic dacarbazine (DTIC). CRISPR-Cas9-mediated CD133 knockout in BAKR cells (BAKR-KO) re-sensitized cells to trametinib. CD133 knockout in BAKP and POT cells increased trametinib-induced apoptosis by reducing anti-apoptotic BCL-xL, p-AKT, and p-BAD and increasing pro-apoptotic BAX. Conversely, Dox-induced CD133 expression diminished apoptosis in both trametinib-treated cell lines, coincident with elevated p-AKT, p-BAD, BCL-2, and BCL-xL and decreased activation of BAX and caspases-3 and -9. AKT1/2 siRNA knockdown or inhibition of BCL-2 family members with navitoclax (ABT-263) in BAKP-KO cells further enhanced caspase-mediated apoptotic PARP cleavage. CD133 may therefore activate a survival pathway where (1) increased AKT phosphorylation and activation induces (2) BAD phosphorylation and inactivation, (3) decreases BAX activation, and (4) reduces caspases-3 and -9 activity and caspase-mediated PARP cleavage, leading to apoptosis suppression and drug resistance in melanoma. Targeting nodes of the CD133, AKT, or BCL-2 survival pathways with trametinib highlights the potential for combination therapies for NRAS-mutant melanoma stem cells for the development of more effective treatments for patients with high-risk melanoma.

BH3-Only Proteins Noxa and Puma Are Key Regulators of Induced Apoptosis.

Apoptosis is an evolutionarily conserved and tightly regulated cell death pathway. Physiological cell death is important for maintaining homeostasis and optimal biological conditions by continuous elimination of undesired or superfluous cells. The BH3-only pro-apoptotic members are strong inducers of apoptosis. The pro-apoptotic BH3-only protein Noxa activates multiple death pathways by inhibiting the anti-apoptotic Bcl-2 family protein, Mcl-1, and other protein members leading to Bax and Bak activation and MOMP. On the other hand, Puma is induced by p53-dependent and p53-independent apoptotic stimuli in several cancer cell lines. Moreover, this protein is involved in several physiological and pathological processes, such as immunity, cancer, and neurodegenerative diseases. Future heat shock research could disclose the effect of hyperthermia on both Noxa and BH3-only proteins. This suggests post-transcriptional mechanisms controlling the translation of both Puma and Noxa mRNA in heat-shocked cells. This study was also the chance to recapitulate the different reactional mechanisms investigated for caspases.

Interferon-γ primes macrophages for pathogen ligand-induced killing via a caspase-8 and mitochondrial cell death pathway

Cell death plays an important role during pathogen infections. Here, we report that interferon-γ (IFNγ) sensitizes macrophages to Toll-like receptor (TLR)-induced death that requires macrophage-intrinsic death ligands and caspase-8 enzymatic activity, which trigger the mitochondrial apoptotic effectors, BAX and BAK. The pro-apoptotic caspase-8 substrate BID was dispensable for BAX and BAK activation. Instead, caspase-8 reduced pro-survival BCL-2 transcription and increased inducible nitric oxide synthase (iNOS), thus facilitating BAX and BAK signaling. IFNγ-primed, TLR-induced macrophage killing required iNOS, which licensed apoptotic caspase-8 activity and reduced the BAX and BAK inhibitors, A1 and MCL-1. The deletion of iNOS or caspase-8 limited SARS-CoV-2-induced disease in mice, while caspase-8 caused lethality independent of iNOS in a model of hemophagocytic lymphohistiocytosis. These findings reveal that iNOS selectively licenses programmed cell death, which may explain how nitric oxide impacts disease severity in SARS-CoV-2 infection and other iNOS-associated inflammatory conditions.

Caffeic acid mitigates aflatoxinB1‐mediated toxicity in the male rat reproductive system by modulating inflammatory and apoptotic responses, testicular function, and the redox‐regulatory systems

Aflatoxin B1 (AFB1 ) is a toxic metabolite of public health concern. The present study investigates the protective effects of caffeic acid (CA) against AFB1 -induced oxidative stress, inflammation, and apoptosis in the hypothalamus, epididymis, and testis of male rats. Five experimental rat cohorts (n = 6) were treated per os for 28 consecutive days as follows: Control (Corn oil 2 ml/kg body weight), AFB1 alone (50μg/kg), CA alone (40 mg/kg) and the co-treated rat cohorts (AFB1 : 50μg/kg + CA1: 20 or 40 mg/kg). Following sacrifice, the biomarkers of hypothalamic, epididymal, and testicular toxicities, antioxidant enzyme activities, myeloperoxidase (MPO) activity, as well as levels of nitric oxide (NO), reactive oxygen and nitrogen (RONS) species and lipid peroxidation (LPO) were analysed spectrophotometrically. Besides, the concentration of tumour necrosis factor-alpha (TNF-α), Bcl-2 and Bax proteins were assessed using ELISA. Results showed that the AFB1 -induced decrease in biomarkers of testicular, epididymal and hypothalamic toxicity was significantly (p < .05) alleviated in rats coexposed to CA. Moreover, the reduction of antioxidant status and the increase in RONS and LPO were lessened (p < .05) in rats co-treated with CA. AFB1 mediated increase in TNF-α, Bax, NO and MPO activity were reduced (p< .05) in the hypothalamus, epididymis, and testis of rats coexposed to CA. In addition, Bcl-2 levels were reduced in rats treated with CA dose-dependently. Light microscopic examination showed that histopathological lesions severity induced by AFB1 were alleviated in rats coexposed to CA. Taken together, the amelioration of AFB1 -induced neuronal and reproductive toxicities by CA involves anti-inflammatory, antioxidant, antiapoptotic mechanisms in rats. PRACTICAL APPLICATIONS: The beneficial antioxidant effects of caffeic acid (CA) are attributed to CA delocalized aromatic rings and free electrons, easily donated to stabilize reactive oxygen species. We report in vivo findings on CA and AfB1 mediated oxidative stress and reproductive dysfunction in rats. CA conjugated esters including chlorogenic acids are widely distributed in plants, and they act as a dietary source of natural defense against infections. CA can chelate heavy metals and reduce production of damaging free radicals to cellular macromolecules. Along these lines, CA can stabilize aflatoxin B1-epoxide as well and avert deleterious conjugates from forming with deoxyribonucleic acids. Hence CA, as a dietary phytochemical can protect against the damaging effects of toxins including aflatoxin B1 that contaminate food. CA dose-dependently abated oxidative, inflammatory, and apoptotic stimuli, improved functional characteristics of spermatozoa and reproductive hormone levels, and prevented histological alterations in experimental rats' hypothalamus and reproductive organs brought about by AFB1 toxicity.

Lipids and divalent cations regulate BH3-independent activation of BAX and Bcl-xL

Regulation of apoptosis is tightly linked with the targeting of numerous Bcl-2 proteins to the mitochondrial outer membrane (MOM), where their activation or inhibition dictates cell death or survival. According to the traditional view of apoptotic regulation, BH3-effector proteins are indispensable for the cytosol-to-MOM targeting and activation of pro- and anti-apoptotic members of the Bcl-2 protein family. This view is challenged by recent studies showing that these processes can occur in cells lacking BH3 effectors by as yet to be determined mechanism(s).