Selectively ablating damaged cells is an evolving therapeutic approach for age-related disease. Current methods for genome-wide screens to identify genes whose deletion might promote the death of damaged or senescent cells are generally underpowered because of the short timescales of cell death as well as the difficulty of scaling non-dividing cells. Here, we establish "Death-seq," a positive-selection CRISPR screen optimized to identify enhancers and mechanisms of cell death. Our screens identified synergistic enhancers of cell death induced by the known senolytic ABT-263. The screen also identified inducers of cell death and senescent cell clearance in models of age-related diseases by a related compound, ABT-199, which alone is not senolytic but exhibits less toxicity than ABT-263. Death-seq enables the systematic screening of cell death pathways to uncover molecular mechanisms of regulated cell death subroutines and identifies drug targets for the treatment of diverse pathological states such as senescence, cancer, and fibrosis.

This study aimed to systematically analyse the pregnancy, birth and demographic-related factors associated with age of death in sudden unexpected infant death (SUID).

Neurons of the central nervous system (CNS) tissue are terminally differentiated cells and have large volumes, unlike cells of peripheral tissues. Such neurons possess abundant lysosomes in which damaged and unneeded intracellular constituents are degraded. A cellular process to bring the unneeded constituents to lysosomes is referred to as macroautophagy (autophagy), which is essential for the maintenance of cellular metabolism under physiological conditions. In fact, mice deficient in Atg7 or Atg5 specifically in CNS tissue have ubiquitin aggregates in neurons and massive loss of cerebral and cerebellar cortical neurons, resulting in neurodegeneration and short life span. In addition, acceleration of autophagy induced by the loss of lysosomal proteinases such as cathepsin D or cathepsins B and L, or by hypoxic/ischemic (H/I) brain injury, causes neurodegeneration. Moreover, lysosomes with undigested materials due to loss of proteinases are enwrapped by double membranes to produce autophagosomes, resulting in the further accumulation of autolysosomes. H/I brain injury at birth that is an important cause of cerebral palsy, mental retardation, and epilepsy causes energy failure, oxidative stress, and unbalanced ion fluxes, leading to a high induction of autophagy in brain neurons. Since mice that are unable to execute autophagy (due to brain-specific deletion of Atg7 or Atg5) die as a result of massive loss of cerebral and cerebellar neurons with accumulation of ubiquitin aggregates, induction of neuronal autophagy after H/I injury is generally considered neuroprotective, as it maintains cellular homeostasis. However, our data showing that H/I injury-induced pyramidal neuron death in the neonatal hippocampus is largely prevented by Atg7 deficiency indicate the presence of autophagic neuron death. In this section, we introduce various methods for the detection of autophagic neuron death in addition to other death modes of CNS neurons.

Caspase-directed apoptosis usually fragments cells, releasing nonfunctional, prothrombogenic, membrane-bound apoptotic bodies marked for rapid engulfment by macrophages. Blood platelets are functional anucleate cells generated by specialized fragmentation of their progenitors, megakaryocytes (MKs), but committed to a constitutive caspase-independent death. Constitutive formation of the proplatelet-bearing MK was recently reported to be caspase-dependent, apparently involving mitochondrial release of cytochrome c, a known pro-apoptogenic factor. We extend those studies and report that activation of caspases in MKs, either constitutively or after Fas ligation, yields platelets that are functionally responsive and evade immediate phagocytic clearance, and retain mitochondrial transmembrane potential until constitutive platelet death ensues. Furthermore, the exclusion from the platelet progeny of caspase-9 present in the progenitor accounts for failure of mitochondrial release of cytochrome c to activate caspase-3 during platelet death. Thus, progenitor cell death by apoptosis can result in birth of multiple functional anucleate daughter cells.

Vertebrate genomes undergo epigenetic reprogramming during development and disease. Emerging evidence suggests that DNA methylation plays a key role in cell fate determination in the retina. Despite extensive studies of the programmed cell death that occurs during retinal development and degeneration, little is known about how DNA methylation might regulate neuronal cell death in the retina.

Desert death is defined as any death that occurs in the desert and could be attributed to a list of causes including environmental, animal related, undetermined, and other causes. Death in the desert seems to be obscure and little discussed in the field of forensic medicine, despite its importance, and there is only limited literature available on this broad topic. This narrative review aims to identify the most common causes of desert death and its medicolegal implications. Desert death causes: Environmental causes of death could be a result of temperature and lightening-related causes. Moreover, a variety of animals found in deserts are considered to be threatening and fatal, in addition to other and undetermined causes. Medicolegal implications of desert death: Likely to arise from the difficulties faced in finding the cause of death are the identification of the victim and the postmortem injuries that occur.

In eukaryotes, the classical form of programmed cell death (PCD) is apoptosis, which has as its specific characteristics DNA fragmentation and membrane depolarization. In Escherichia coli a different PCD system has been reported. It is mediated by the toxin-antitoxin system module mazEF. The E. coli mazEF module is one of the most thoroughly studied toxin-antitoxin systems. mazF encodes a stable toxin, MazF, and mazE encodes a labile antitoxin, MazE, which prevents the lethal effect of MazF. mazEF-mediated cell death is a population phenomenon requiring the quorum-sensing pentapeptide NNWNN designated Extracellular Death Factor (EDF). mazEF is triggered by several stressful conditions, including severe damage to the DNA. Here, using confocal microscopy and FACS analysis, we show that under conditions of severe DNA damage, the triggered mazEF-mediated cell death pathway leads to the inhibition of a second cell death pathway. The latter is an apoptotic-like death (ALD); ALD is mediated by recA and lexA. The mazEF-mediated pathway reduces recA mRNA levels. Based on these results, we offer a molecular model for the maintenance of an altruistic characteristic in cell populations. In our model, the ALD pathway is inhibited by the altruistic EDF-mazEF-mediated death pathway.

Epidermal keratinocytes undergo a unique form of terminal differentiation and programmed cell death known as cornification. Cornification leads to the formation of the outermost skin barrier, i.e. the cornified layer, as well as to the formation of hair and nails. Different genes are expressed in coordinated waves to provide the structural and regulatory components of cornification. Differentiation-associated keratin intermediate filaments form a complex scaffold accumulating in the cytoplasm and, upon removal of cell organelles, fill the entire cell interior mainly to provide mechanical strength. In addition, a defined set of proteins is cross-linked by transglutamination in the cell periphery to form the so-called cornified envelope. Extracellular modifications include degradation of the tight linkages between corneocytes by excreted proteases, which allows corneocyte shedding by desquamation, and stacking and modification of the excreted lipids that fill the intercellular spaces between corneocytes to provide a water-repellant barrier. In hard skin appendages such as hair and nails these tight intercorneocyte connections remain permanent. Various lines of evidence exist for a role of organelle disintegration, proteases, nucleases, and transglutaminases contributing to the actual cell death event. However, many mechanistic aspects of kearatinocyte death during cornification remain elusive. Importantly, it has recently become clear that keratinocytes activate anti-apoptotic and anti-necroptotic pathways to prevent premature cell death during terminal differentiation. This review gives an overview of the current concept of cornification as a mode of programmed cell death and the anti-cell death mechanisms in the epidermis that secure epidermal homeostasis. This article is part of a Special Section entitled: Cell Death Pathways.

Efficient adjuvants have the potential to trigger both innate and adaptive immune responses simultaneously. Flagellin is a unique pathogen-derived protein, which is recognized by pattern recognition receptors (PRRs) as well as by B-cell and T cell receptors thus providing an important link between innate and adaptive immunity. The aforementioned properties define flagellin as an optimal adjuvant. The induction of immunogenic cell death could be an additional expectation for adjuvants in the context of cancer immunotherapy due to their ability to activate dendritic cells (DC) to present tumor antigens through the engulfment of dying cells. The immunostimulatory potential of flagellin in the course of DC and lymphocyte activation is well documented, however the exact mechanism is not fully explored. Based on this limitation we sought to investigate the potential modulatory effects of flagellin on various cell death processes knowing that it plays detrimental roles in regulating the final outcome of various types of immune responses. Here we provide evidence that the pre-treatment of Jurkat T-cells with recombinant flagellin is able to increase the degree of cell death provoked by FasL or TNF-α, and concomitantly increases the cytotoxic potential of phytohemagglutinin activated T-lymphocytes in a TLR5 dependent way. In contrast to these flagellin-mediated effects on the death receptor-induced signaling events, the mitochondrial apoptotic pathway remained unaffected. Furthermore, the cell culture supernatant of wild type Salmonella enteritidis bacteria, but not their flagellin deficient variant, was able to enhance the Fas-induced cell death process. To define the molecular mechanisms of flagellin-mediated elevated levels of cell death we were able to detect the upregulation of RIP1-dependent signaling events. These findings demonstrate that the cooperative actions of pattern recognition and different death receptors are able to initiate the cell death process with the mobilization of RIP-dependent cell death modalities. This finding highlights the capability of flagellin to act as a potential adjuvant which is relevant for tumor immunotherapy.

About 50% of spinal motoneurons undergo programmed cell death (PCD) after target contact, but little is known about how this process is initiated. Embryonic motoneurons coexpress the death receptor Fas and its ligand FasL at the stage at which PCD is about to begin. In the absence of trophic factors, many motoneurons die in culture within 2 d. Most (75%) of these were saved by Fas-Fc receptor body, which blocks interactions between Fas and FasL, or by the caspase-8 inhibitor tetrapeptide IETD. Therefore, activation of Fas by endogenous FasL underlies cell death induced by trophic deprivation. In the presence of neurotrophic factors, exogenous Fas activators such as soluble FasL or anti-Fas antibodies triggered PCD of 40-50% of purified motoneurons over the following 3-5 d; this treatment led to activation of caspase-3, and was blocked by IETD. Sensitivity to Fas activation is regulated: motoneurons cultured for 3 d with neurotrophic factors became completely resistant. Levels of Fas expressed by motoneurons varied little, but FasL was upregulated in the absence of neurotrophic factors. Motoneurons resistant to Fas activation expressed high levels of FLICE-inhibitory protein (FLIP), an endogenous inhibitor of caspase-8 activation. Our results suggest that Fas can act as a driving force for motoneuron PCD, and raise the possibility that active triggering of PCD may contribute to motoneuron loss during normal development and/or in pathological situations.

Internet gaming disorder (IGD) is an emerging problem. Rarely, media reports about people, who have died during playing video games, but thus far no systematic, scientific study is available about the topic. We investigated such cases, looking for common characteristics, connection between gaming and death, and the possible reasons leading to death.

It is poorly understood how public perception of the difference between brain death and circulatory death may influence attitudes towards organ donation. We investigated the public opinion on brain death versus circulatory death and documented inconsistencies in the legislations of countries with different cultural and socioeconomic backgrounds.

Monoclonal antibodies blocking the programmed cell death-1 (PD-1) or its ligand (PD-L1) are a group of immune checkpoints inhibitors (ICIs) with proven antitumor efficacy. However, their use is complicated by immune-related adverse events (irAEs), including endocrine adverse events (eAEs).

Sustained p38(MAPK) phosphorylation upregulates p75 neurotrophin (p75(NTR)) and induces apoptosis in Ewing's sarcoma family of tumours (ESFT). As fenretinide induces ESFT death through sustained p38(MAPK) phosphorylation, we hypothesised that this may be effected through upregulation of death receptors (DRs) and that treatment of fenretinide plus DR ligands may enhance apoptosis.

This study explores the dilemma in cellular signaling that triggering of CD95 (Fas/APO-1) in some situations results in cell death and in others leads to the activation of NF-kappaB. We established an integrated kinetic mathematical model for CD95-mediated apoptotic and NF-kappaB signaling. Systematic model reduction resulted in a surprisingly simple model well approximating experimentally observed dynamics. The model postulates a new link between c-FLIP(L) cleavage in the death-inducing signaling complex (DISC) and the NF-kappaB pathway. We validated experimentally that CD95 stimulation resulted in an interaction of p43-FLIP with the IKK complex followed by its activation. Furthermore, we showed that the apoptotic and NF-kappaB pathways diverge already at the DISC. Model and experimental analysis of DISC formation showed that a subtle balance of c-FLIP(L) and procaspase-8 determines life/death decisions in a nonlinear manner. We present an integrated model describing the complex dynamics of CD95-mediated apoptosis and NF-kappaB signaling.

Death-associated protein kinase (DAPk) is a calcium/calmodulin-regulated Ser/Thr-protein kinase that functions at an important point of integration for cell death signaling pathways. DAPk has a structurally unique multi-domain architecture, including a C-terminally positioned death domain (DD) that is a positive regulator of DAPk activity. In this study, recombinant DAPk-DD was observed to aggregate readily and could not be prepared in sufficient yield for structural analysis. However, DAPk-DD could be obtained as a soluble protein in the form of a translational fusion protein with the B1 domain of streptococcal protein G. In contrast to other DDs that adopt the canonical six amphipathic α-helices arranged in a compact fold, the DAPk-DD was found to possess surprisingly low regular secondary structure content and an absence of a stable globular fold, as determined by circular dichroism (CD), NMR spectroscopy and a temperature-dependent fluorescence assay. Furthermore, we measured the in vitro interaction between extracellular-regulated kinase-2 (ERK2) and various recombinant DAPk-DD constructs. Despite the low level of structural order, the recombinant DAPk-DD retained the ability to interact with ERK2 in a 1∶1 ratio with a K d in the low micromolar range. Only the full-length DAPk-DD could bind ERK2, indicating that the apparent 'D-motif' located in the putative sixth helix of DAPk-DD is not sufficient for ERK2 recognition. CD analysis revealed that binding of DAPk-DD to ERK2 is not accompanied by a significant change in secondary structure. Taken together our data argue that the DAPk-DD, when expressed in isolation, does not adopt a classical DD fold, yet in this state retains the capacity to interact with at least one of its binding partners. The lack of a stable globular structure for the DAPk-DD may reflect either that its folding would be supported by interactions absent in our experimental set-up, or a limitation in the structural bioinformatics assignment of the three-dimensional structure.

Casitas B-lineage lymphoma-b (Cbl-b) is an E3 ubiquitin ligase that negatively regulates T cell activation. Cbl-b-/- T cells are hyper-reactive and co-stimulation independent, and Cbl-b-/- mice demonstrate robust T cell and NK cell-mediated antitumor immunity. As a result of these murine studies, Cbl-b is considered a potential target for therapeutic manipulation in human cancer immunotherapy. The PD-L1/PD-1 pathway of immune regulation is presently an important therapeutic focus in tumor immunotherapy, and although Cbl-b-/- mice have been shown to be resistant to several immuno-regulatory mechanisms, the sensitivity of Cbl-b-/- mice to PD-L1-mediated suppression has not been reported. We now document that Cbl-b-/- T cells and NK cells are resistant to PD-L1/PD-1-mediated suppression. Using a PD-L1 fusion protein (PD-L1 Ig), this resistance is shown for both in vitro proliferative responses and IFN-γ production and is not associated with decreased PD-1 expression on Cbl-b-/- cells. In coculture studies, Cbl-b-/- CD8+, but not CD4+ T cells, diminish the PD-L1 Ig-mediated suppression of bystander naïve WT CD8+ T cells. Using an in vivo model of B16 melanoma in which numerous liver metastases develop in WT mice in a PD-1 dependent manner, Cbl-b-/- mice develop significantly fewer liver metastases without the administration of anti-PD-1 antibody. Overall, our findings identify a new mode of immuno-regulatory resistance associated with Cbl-b deficiency and suggest that resistance to PD-L1/PD-1-mediated suppression is a novel mechanism by which Cbl-b deficiency leads to enhanced antitumor immunity. Our results suggest that targeting Cbl-b in cancer immunotherapy offers the opportunity to simultaneously override numerous relevant "checkpoints," including sensitivity to regulatory T cells, suppression by TGF-β, and immune regulation by both CTLA-4 and, as we now report, by the PD-L1/PD-1 pathway.

Evidence suggests that programmed death receptor-1/programmed death ligand-1 (PD-1/PD-L1) targeted inhibitors act as an immune checkpoint blockade, indicating that these compounds may be useful in cancer immunotherapy by inhibiting the immune response between T-cells and tumors. Previous studies have shown that ginsenosides can regulate the expression of PD-1 and PD-L1 in target diseases; however, it remains unknown whether ginsenosides act as a blockade of PD-1/PD-L1 interactions. In this study, we used competitive ELISA to investigate 12 ginsenosides for their ability to block PD-1/PD-L1 interactions. In addition, we performed a protein-ligand docking simulation and examined the hydrophobic interactions and hydrogen bonds formed at the interfaces between the ginsenosides and PD-L1/PD-1. Eight out of the 12 ginsenosides studied showed inhibition of PD-1/PD-L1 interactions at 35% at the maximum concentration (1 μM). Among them, Rg3 and Compound K (C-K) demonstrated the highest inhibitory effects. Rg3 and C-K were further identified for their interaction efficacy with PD-1/PD-L1, which supported our results demonstrating the blocking activity of these compounds against PD-1/PD-L1 binding interactions. Collectively, our findings suggest that some ginsenosides, including Rg3 and C-K, inhibit PD-1/PD-L1 binding interactions. Therefore, these compounds may prove useful as part of an overall immuno-oncological strategy.

Death and the anxiety of it becomes more apparent when confronted with a chronic disease. Even though multiple sclerosis (MS) is a treatable condition today, it is still accompanied by a multitude of impairments, which in turn may intensify of death anxiety.

Infections with Staphylococcus aureus, a common inducer of septic and toxic shock, often result in tissue damage and death of various cell types. Although S. aureus was suggested to induce apoptosis, the underlying signal transduction pathways remained elusive. We show that caspase activation and DNA fragmentation were induced not only when Jurkat T cells were infected with intact bacteria, but also after treatment with supernatants of various S. aureus strains. We also demonstrate that S. aureus-induced cell death and caspase activation were mediated by alpha-toxin, a major cytotoxin of S. aureus, since both events were abrogated by two different anti-alpha-toxin antibodies and could not be induced with supernatants of an alpha-toxin-deficient S. aureus strain. Furthermore, alpha-toxin-induced caspase activation in CD95-resistant Jurkat sublines lacking CD95, Fas-activated death domain, or caspase-8 but not in cells stably expressing the antiapoptotic protein Bcl-2. Together with our finding that alpha-toxin induces cytochrome c release in intact cells and, interestingly, also from isolated mitochondria in a Bcl-2-controlled manner, our results demonstrate that S. aureus alpha-toxin triggers caspase activation via the intrinsic death pathway independently of death receptors. Hence, our findings clearly define a signaling pathway used in S. aureus-induced cytotoxicity and may provide a molecular rationale for future therapeutic interventions in bacterial infections.