Apoptotic volume decrease as a geometric determinant for cell dismantling into apoptotic bodies

Cell apoptosis, autophagy and necroptosis in osteosarcoma treatment

Osteosarcoma is the most common primary bone tumor in children and adolescents. Although combined therapy including surgery and multi-agent chemotherapy have resulted in great improvements in the overall survival of patients, chemoresistance remains an obstacle for the treatment of osteosarcoma. Molecular targets or effective agents that are actively involved in cell death including apoptosis, autophagy and necroptosis have been studied. We summarized how these agents (novel compounds, miRNAs, or proteins) regulate apoptotic, autophagic and necroptotic pathways; and discussed the current knowledge on the role of these new agents in chemotherapy resistance in osteosarcoma.

Ganoderma lucidum polysaccharides target a Fas/caspase dependent pathway to induce apoptosis in human colon cancer cells

Ganoderma lucidum polysaccharides (GLP) extracted from Ganoderma lucidum have been shown to induce cell death in some kinds of cancer cells. This study investigated the cytotoxic and apoptotic effect of GLP on HCT-116 human colon cancer cells and the molecular mechanisms involved. Cell proliferation, cell migration, lactate dehydrogenase (LDH) levels and intracellular free calcium levels ([Ca(2+)]i) were determined by MTT, wound-healing, LDH release and fluorescence assays, respectively. Cell apoptosis was observed by scanning and transmission electron microscopy. For the mechanism studies, caspase-8 activation, and Fas and caspase-3 expression were evaluated. Treatment of HCT-116 cells with various concentrations of GLP (0.625-5 mg/mL) resulted in a significant decrease in cell viability (P< 0.01). This study showed that the antitumor activity of GLP was related to cell migration inhibition, cell morphology changes, intracellular Ca(2+) elevation and LDH release. Also, increase in the levels of caspase-8 activity was involved in GLP-induced apoptosis. Western blotting indicated that Fas and caspase-3 protein expression was up-regulated after exposure to GLP. This investigation demonstrated for the first time that GLP shows prominent anticancer activities against the HCT-116 human colon cancer cell line through triggering intracellular calcium release and the death receptor pathway.

Pathophysiological role of different tubular epithelial cell death modes in acute kidney injury

The histological substrate of many forms of intrinsic acute kidney injury (AKI) has been classically attributed to tubular necrosis. However, more recent studies indicate that necrosis is not the main form of cell death in AKI and that other forms such as apoptosis, regulated necrosis (i.e. necroptosis and parthanatos), autophagic cell death and mitotic catastrophe, also participate in AKI and that their contribution depends on the cause and stage of AKI. Herein, we briefly summarize the main characteristics of the major types of cell death and we also critically review the existing evidence on the occurrence of different types of cell death reported in the most common experimental models of AKI and human specimens. We also discuss the pathophysiological mechanisms linking tubule epithelial cell death with reduced glomerular filtration, azotaemia and hydroelectrolytic imbalance. For instance, special relevance is given to the analysis of the inflammatory component of some forms of cell death over that of others, as an important and differential pathophysiological determinant. Finally, known molecular mechanisms and signalling pathways involved in each cell death type pose appropriate targets to specifically prevent or reverse AKI, provided that further knowledge of their participation and repercussion in each AKI syndrome is progressively increased in the near future.

Caspases: a molecular switch node in the crosstalk between autophagy and apoptosis

Autophagy and apoptosis are two important catabolic processes contributing to the maintenance of cellular and tissue homeostasis. Autophagy controls the turnover of protein aggregates and damaged organelles within cells, while apoptosis is the principal mechanism by which unwanted cells are dismantled and eliminated from organisms. Despite marked differences between these two pathways, they are highly interconnected in determining the fate of cells. Intriguingly, caspases, the primary drivers of apoptotic cell death, play a critical role in mediating the complex crosstalk between autophagy and apoptosis. Pro-apoptotic signals can converge to activate caspases to execute apoptotic cell death. In addition, activated caspases can degrade autophagy proteins (i.e., Beclin-1, Atg5, and Atg7) to shut down the autophagic response. Moreover, caspases can convert pro-autophagic proteins into pro-apoptotic proteints to trigger apoptotic cell death instead. It is clear that caspases are important in both apoptosis and autophagy, thus a detailed deciphering of the role of caspases in these two processes is still required to clarify the functional relationship between them. In this article, we provide a current overview of caspases in its interplay between autophagy and apoptosis. We emphasized that defining the role of caspases in autophagy-apoptosis crosstalk will provide a framework for more precise manipulation of these two processes during cell death.

The properties of microparticles from RAW 264.7 macrophage cells undergoing in vitro activation or apoptosis

Microparticles (MPs) are small, membrane-bound vesicles that arise from dead and dying cells, and display pro-inflammatory and pro-thrombotic activity. As shown previously, the RAW 264.7 murine macrophage cell line can release MPs following stimulation with LPS or polyinosinic:polycytidylic acid [poly (I:C)], ligands of TLR4 and TLR3 respectively. To determine the relationship of these MPs to those released during apoptosis, the nucleic acid content of MPs from cultures stimulated with LPS or poly (I:C) was compared with the nucleic acid content of MPs from untreated cells or cells induced to undergo apoptosis by treatment with etoposide or staurosporine (STS). As results of these studies showed, MPs from activated, apoptotic and untreated cells had features in common, as demonstrated by binding of the nucleic acid dyes SYTO 13 and propidium iodide; molecular mass of DNA; and binding of monoclonal anti-DNA and anti-nucleosome Abs. While MPs from the different culture conditions all contained ribosomal RNA, ribosomal RNA from MPs from STS-treated cells showed cleavage and degradation. Taken together, these studies indicate that the nucleic acid content of MPs from activated and apoptotic cells have important similarities, suggesting that events during TLR activation may lead to apoptosis and subsequent MP release.

Possible causes of apoptotic volume decrease: an attempt at quantitative review

Cell shrinkage and dehydration are essential characteristics of apoptosis, and loss of as much as half of the initial cell volume is not uncommon. This phenomenon is usually explained by efflux of K+and Cl−. We reexamine this hypothesis on the basis of the available data for ion concentrations and the requirements for osmotic equilibrium and electroneutrality. In addition to ion loss, we discuss the possible impacts of several other processes: efflux of low-molecular-weight osmolytes, acidification of the cytosol, effects of water channels and pumps, heterogeneity of intracellular water, and dissociation of apoptotic bodies. We conclude that most mammalian cells are theoretically capable of reducing their volume by 15–20% through ion loss or a decrease in cytosolic pH, although, in reality, the contribution of these mechanisms to apoptotic shrinkage may be smaller. Transitions between osmotically active and inactive water pools might influence cell volume as well; these mechanisms are poorly understood but are amenable to experimental study. Dissociation of apoptotic bodies is a separate mechanism of volume reduction and should be monitored closely; this can be best achieved by measurement of intracellular water, rather than cell volume.

Novel insights into the mechanism of cell-based therapy after chronic myocardial infarction

Cell transplantation therapy is considered a novel and promising strategy in regenerative medicine. Recent studies point out that paracrine effects and inflammation induced by transplanted cells are key factors for the improvement of myocardial function. The present study aims at differentiating paracrine effects from inflammatory reactions after cell transplantation. Therefore, in vitro induced apoptotic bodies were transplanted after myocardial infarction in a rat model. Eight weeks after transplantation, the functional results showed no improvement in left ventricular function. Histological analysis revealed no significant differences in the amount of infiltrated cells and collagen content did not differ among the four groups, which sustains the functional data. Surprisingly, angiogenesis increased in groups with apoptotic bodies derived from HUVEC and endothelial progenitor cells, but not from fibroblasts. A complex genetic analysis of apoptotic bodies indicated that miRNAs could be responsible for these changes. Our study demonstrates that inflammatory reaction is critical for scar remodelling and improvement of the heart function after late cell therapy, while neoangiogenesis alone is not sufficient to improve heart function.

Membrane damaging activity of a maslinic acid analog

Close inspection of human ovarian cancer cells A2780 in the course of an antitumor screening using maslinic acid analogs revealed for one of the compounds, 4-oxa-4-phenyl-butyl 2,3-dihydroxy-olean-12-en-28-oate (1), an unusual behavior. During the incubation of the cells with 1, at the perimeter of the cells or close by crystals were formed consisting of cholesterol and excess 1. Compound 1 was incorporated into the cell's membrane followed by an extrusion of cholesterol from the lipid rafts. As a consequence of the alterations of the cell membrane, a volume decrease was initiated that triggered apoptosis; this extends previous models on apoptosis initiating mechanisms.

Role of ion transport in control of apoptotic cell death

Cell shrinkage is a hallmark and contributes to signaling of apoptosis. Apoptotic cell shrinkage requires ion transport across the cell membrane involving K(+) channels, Cl(-) or anion channels, Na(+)/H(+) exchange, Na(+),K(+),Cl(-) cotransport, and Na(+)/K(+)ATPase. Activation of K(+) channels fosters K(+) exit with decrease of cytosolic K(+) concentration, activation of anion channels triggers exit of Cl(-), organic osmolytes, and HCO3(-). Cellular loss of K(+) and organic osmolytes as well as cytosolic acidification favor apoptosis. Ca(2+) entry through Ca(2+)-permeable cation channels may result in apoptosis by affecting mitochondrial integrity, stimulating proteinases, inducing cell shrinkage due to activation of Ca(2+)-sensitive K(+) channels, and triggering cell-membrane scrambling. Signaling involved in the modification of cell-volume regulatory ion transport during apoptosis include mitogen-activated kinases p38, JNK, ERK1/2, MEKK1, MKK4, the small G proteins Cdc42, and/or Rac and the transcription factor p53. Osmosensing involves integrin receptors, focal adhesion kinases, and tyrosine kinase receptors. Hyperosmotic shock leads to vesicular acidification followed by activation of acid sphingomyelinase, ceramide formation, release of reactive oxygen species, activation of the tyrosine kinase Yes with subsequent stimulation of CD95 trafficking to the cell membrane. Apoptosis is counteracted by mechanisms involved in regulatory volume increase (RVI), by organic osmolytes, by focal adhesion kinase, and by heat-shock proteins. Clearly, our knowledge on the interplay between cell-volume regulatory mechanisms and suicidal cell death is still far from complete and substantial additional experimental effort is needed to elucidate the role of cell-volume regulatory mechanisms in suicidal cell death.

Ionic regulation of cell volume changes and cell death after ischemic stroke

Stroke is a leading cause of human death and disability in the USA and around the world. Shortly after the cerebral ischemia, cell swelling is the earliest morphological change in injured neuronal, glial, and endothelial cells. Cytotoxic swelling directly results from increased Na(+) (with H2O) and Ca(2+) influx into cells via ionic mechanisms evoked by membrane depolarization and a number of harmful factors such as glutamate accumulation and the production of oxygen reactive species. During the sub-acute and chronic phases after ischemia, injured cells may show a phenotype of cell shrinkage due to complex processes involving membrane receptors/channels and programmed cell death signals. This review will introduce some progress in the understanding of the regulation of pathological cell volume changes and the involved receptors and channels, including NMDA and AMPA receptors, acid-sensing ion channels, hemichannels, transient receptor potential channels, and KCNQ channels. Moreover, accumulating evidence supports a key role of energy deficiency and dysfunction of Na(+)/K(+)-ATPase in ischemia-induced cell volume changes and cell death. Specifically, the Na(+) pump failure is a prerequisite for disruption of ionic homeostasis including a pro-apoptotic disruption of the K(+) homeostasis. Finally, we will introduce the concept of hybrid cell death as a result of the Na(+) pump failure in cultured cells and the ischemic brain. The goal of this review is to outline recent understanding of the ionic mechanism of ischemic cytotoxicity and suggest innovative ideas for future translational research.

Exosomes in prostate cancer: putting together the pieces of a puzzle

Exosomes have been shown to act as mediators for cell to cell communication and as a potential source of biomarkers for many diseases, including prostate cancer. Exosomes are nanosized vesicles secreted by cells and consist of proteins normally found in multivesicular bodies, RNA, DNA and lipids. As a potential source of biomarkers, exosomes have attracted considerable attention, as their protein content resembles that of their cells of origin, even though it is noted that the proteins, miRNAs and lipids found in the exosomes are not a reflective stoichiometric sampling of the contents from the parent cells. While the biogenesis of exosomes in dendritic cells and platelets has been extensively characterized, much less is known about the biogenesis of exosomes in cancer cells. An understanding of the processes involved in prostate cancer will help to further elucidate the role of exosomes and other extracellular vesicles in prostate cancer progression and metastasis. There are few methodologies available for general isolation of exosomes, however validation of those methodologies is necessary to study the role of exosomal-derived biomarkers in various diseases. In this review, we discuss “exosomes” as a member of the family of extracellular vesicles and their potential to provide candidate biomarkers for prostate cancer.

Drug-induced reactivation of apoptosis abrogates HIV-1 infection

HIV-1 blocks apoptosis, programmed cell death, an innate defense of cells against viral invasion. However, apoptosis can be selectively reactivated in HIV-infected cells by chemical agents that interfere with HIV-1 gene expression. We studied two globally used medicines, the topical antifungal ciclopirox and the iron chelator deferiprone, for their effect on apoptosis in HIV-infected H9 cells and in peripheral blood mononuclear cells infected with clinical HIV-1 isolates. Both medicines activated apoptosis preferentially in HIV-infected cells, suggesting that the drugs mediate escape from the viral suppression of defensive apoptosis. In infected H9 cells, ciclopirox and deferiprone enhanced mitochondrial membrane depolarization, initiating the intrinsic pathway of apoptosis to execution, as evidenced by caspase-3 activation, poly(ADP-ribose) polymerase proteolysis, DNA degradation, and apoptotic cell morphology. In isolate-infected peripheral blood mononuclear cells, ciclopirox collapsed HIV-1 production to the limit of viral protein and RNA detection. Despite prolonged monotherapy, ciclopirox did not elicit breakthrough. No viral re-emergence was observed even 12 weeks after drug cessation, suggesting elimination of the proviral reservoir. Tests in mice predictive for cytotoxicity to human epithelia did not detect tissue damage or activation of apoptosis at a ciclopirox concentration that exceeded by orders of magnitude the concentration causing death of infected cells. We infer that ciclopirox and deferiprone act via therapeutic reclamation of apoptotic proficiency (TRAP) in HIV-infected cells and trigger their preferential elimination. Perturbations in viral protein expression suggest that the antiretroviral activity of both drugs stems from their ability to inhibit hydroxylation of cellular proteins essential for apoptosis and for viral infection, exemplified by eIF5A. Our findings identify ciclopirox and deferiprone as prototypes of selectively cytocidal antivirals that eliminate viral infection by destroying infected cells. A drug-based drug discovery program, based on these compounds, is warranted to determine the potential of such agents in clinical trials of HIV-infected patients.

MicroRNA-152 and -181a participate in human dermal fibroblasts senescence acting on cell adhesion and remodeling of the extra-cellular matrix

Ageing of human skin is associated with phenotypic changes in the cutaneous cells; the major functional markers of ageing occur as consequences of dermal and epidermal cell senescence and of structural and compositional remodeling of normally long-lived dermal extracellular matrix proteins. Understanding the contribution of the dermal cells in skin ageing is a key question, since this tissue is particularly important for skin integrity and its properties can affect the epidermis. Several microRNAs have been shown to be involved in the regulation of pathways involved in cellular senescence and exerted important effects on tissues ageing. In this study, we demonstrate that the expression of miR-152 and miR-181a increased during the human dermal fibroblasts senescence and that their overexpression, is sufficient to induce cellular senescence in early-passage cells. The increase of these miRNAs during cells senescence was accompanied by a decrease in integrin α5 and collagen XVI expression at mRNA and/or protein levels resulting in reduced cellular adhesion and suggesting extracellular matrix remodeling. These findings indicate that changes in miRNAs expression, by modulating the levels of adhesion proteins and extra-cellular matrix components, such as integrin α5 and collagen XVI, could contribute to the compositional remodelling of the dermis and epidermis occurring during skin aging.

Nutrient availability links mitochondria, apoptosis, and obesity

Mitochondria are the dominant source of the cellular energy requirements through oxidative phosphorylation, but they are also central players in apoptosis. Nutrient availability may have been the main evolutionary driving force behind these opposite mitochondrial functions: production of energy to sustain life and release of apoptotic proteins to trigger cell death. Here, we explore the link between nutrients, mitochondria and apoptosis with known and potential implications for age-related decline and metabolic syndromes.

Morphological Features of Organelles during Apoptosis: An Overview

An apoptotic program leading to controlled cell dismantling implies perturbations of nuclear dynamics, as well as changes affecting the organelle structure and distribution. In human cancer cells driven to apoptosis by different stimuli, we have recently investigated the morphological properties of several organelles, including mitochondria, lysosomes, endoplasmic reticulum and Golgi apparatus. In this review, we will discuss the body of evidence in the literature suggesting that organelles are generally relocated and/or degraded during apoptosis, irrespectively of the apoptogenic stimulus and cell type.

Blebbishields, the emergency program for cancer stem cells: sphere formation and tumorigenesis after apoptosis

Caspases mediate apoptosis and have also been implicated in stem-cell biology. How caspases are linked to stem-cell biology is not known. Here, we show that the apoptotic blebs of cancer cells fuse together to form novel structures called 'blebbishields'. Blebbishields form spheres by fusion. Both blebbishield formation and sphere formation involve active caspases and N-linked glycosylation. Sphere formation is enhanced by acidic pH and is counteracted by inhibitors of proton pump, caspases, and cholesterol. The blebbishields from VEGFR2(High) cells are capable of enhanced sphere formation. Blebbishields express transiently downregulated stem-cell markers and the sphere-forming blebbishield-derived cells are tumorigenic. Our study demonstrates that the cancer stem cells can survive after apoptosis by blebbishield formation and subsequent sphere formation.

Swelling rather than shrinkage precedes apoptosis in serum-deprived vascular smooth muscle cells

Contrasting cell volume behaviours (swelling vs. shrinkage) are considered as criteria to distinguish necrosis from apoptosis. In this study, we employed a time-lapse, dual-image surface reconstruction technique to assess the volume of single vascular smooth muscle cells transfected with E1A-adenoviral protein (E1A-VSMC) and undergoing rapid apoptosis in the absence of growth factors or in the presence of staurosporine. After 30- to 60-min lag-phase, serum-deprived E1A-VSMC volume was increased by ~40%, which preceded maximal increments of caspase-3 activity and chromatin cleavage. Swollen cells underwent rapid apoptotic collapse, documented by plasma membrane budding, and terminated in 10-15 min by the formation of numerous apoptotic bodies. Suppression of apoptosis by inhibition of Na(+),K(+)-ATPase and activation of cAMP signalling with ouabain and forskolin, respectively, completely abolished the swelling of serum-deprived E1A-VSMC. In contrast to serum deprivation, apoptotic collapse of staurosporine-treated E1A-VSMC preceded attenuation of their volume by ~30%. Neither transient hyposmotic swelling nor isosmtotic shrinkage triggered apoptosis. Our results show that cell shrinkage can not be considered as ubiquitous hallmark of apoptosis. The involvement of stimulus-specific cell volume perturbations in initiation and progression of apoptosis in vascular smooth muscle cells should be examined further.

Caspase activation regulates the extracellular export of autophagic vacuoles

The endothelium plays a central role in the regulation of vascular wall cellularity and tone by secreting an array of mediators of importance in intercellular communication. Nutrient deprivation of human endothelial cells (EC) evokes unconventional forms of secretion leading to the release of nanovesicles distinct from apoptotic bodies and bearing markers of multivesicular bodies (MVB). Nutrient deficiency is also a potent inducer of autophagy and vesicular transport pathways can be assisted by autophagy. Nutrient deficiency induced a significant and rapid increase in autophagic features, as imaged by electron microscopy and immunoblotting analysis of LC3-II/LC3-I ratios. Increased autophagic flux was confirmed by exposing serum-starved cells to bafilomycin A 1. Induction of autophagy was followed by indices of an apoptotic response, as assessed by microscopy and poly (ADP-ribose) polymerase cleavage in absence of cell membrane permeabilization indicative of necrosis. Pan-caspase inhibition with ZVAD-FMK did not prevent the development of autophagy but negatively impacted autophagic vacuole (AV) maturation. Adopting a multidimensional proteomics approach with validation by immunoblotting, we determined that nutrient-deprived EC released AV components (LC3I, LC3-II, ATG16L1 and LAMP2) whereas pan-caspase inhibition with ZVAD-FMK blocked AV release. Similarly, nutrient deprivation in aortic murine EC isolated from CASP3/caspase 3-deficient mice induced an autophagic response in absence of apoptosis and failed to prompt LC3 release. Collectively, the present results demonstrate the release of autophagic components by nutrient-deprived apoptotic human cells in absence of cell membrane permeabilization. These results also identify caspase-3 as a novel regulator of AV release.

Exosomes: vesicular carriers for intercellular communication in neurodegenerative disorders

The intercellular transfer of misfolded proteins has received increasing attention in various neurodegenerative diseases characterized by the aggregation of specific proteins, as observed in Alzheimer's, Parkinson's and Huntington's disease. One hypothesis holds that intercellular dissemination of these aggregates within the central nervous system results in the seeded assembly of the cognate soluble protein in target cells, similar to that proposed for transmissible prion diseases. The molecular mechanisms underlying the intercellular transfer of these proteinaceous aggregates are poorly understood. Various transfer modes of misfolded proteins including continuous cell-cell contacts such as nanotubes, unconventional secretion or microvesicle/exosome-associated dissemination have been suggested. Cells can release proteins, lipids and nucleic acids by vesicular exocytosis pathways destined for horizontal transfer. Encapsulation into microvesicular/exosomal vehicles not only protects these molecules from degradation and dilution in the extracellular space but also facilitates delivery over large distances, e.g. within the blood flow or interstitial fluid. Specific surface ligands might allow the highly efficient and targeted uptake of these vesicles by recipient cells. In this review, we focus on the cell biology and function of neuronal microvesicles/exosomes and discuss the evidence for pathogenic intercellular protein transfer mediated by vesicular carriers.

Villous trophoblast apoptosis is elevated and restricted to cytotrophoblasts in pregnancies complicated by preeclampsia, IUGR, or preeclampsia with IUGR

Human placental villi are surfaced by an outer multinucleated syncytiotrophoblast and underlying mononucleated cytotrophoblasts. Conflicting data have attributed one, or the other, of these villous trophoblast phenotypes to undergo enhanced apoptosis in complicated pregnancies, compared to term, normotensive pregnancies. We use high-resolution confocal microscopy after co-staining for E-cadherin, as a trophoblast plasma membrane marker, and for the cleavage products of cytokeratin 18 and PARP1, as markers for caspase-mediated apoptosis, to distinguish between apoptotic cytotrophoblasts and apoptosis within the syncytiotrophoblast. We test the hypothesis that increased caspase-mediated apoptosis occurs in villi of placentas derived from pregnancies complicated by preeclampsia, intrauterine growth restriction (IUGR), or both. We find significantly elevated apoptosis in villous cytotrophoblasts from women with preeclampsia and/or IUGR, compared to term, normotensive pregnancies. Apoptosis of cytotrophoblasts in villi from complicated pregnancies appears to progress similarly to what we found previously for apoptotic cytotrophoblasts in villi from in term, normotensive pregnancies. Notably, caspase-mediated apoptosis was not detectable in regions with intact syncytiotrophoblast, suggesting strong repression of apoptosis in this trophoblast phenotype in vivo. We suggest that the elevated apoptosis in cytotrophoblasts in preeclampsia contributes to the placental dysfunction characteristic of this disorder. We also propose that repression of apoptosis in the syncytiotrophoblast is important to prevent apoptosis sweeping throughout the syncytium, which would result in widespread death of this essential interface for maternal-fetal exchange.

Pseudomonas aeruginosa biofilm-associated homoserine lactone C12 rapidly activates apoptosis in airway epithelia

Pseudomonas aeruginosa (PA) forms biofilms in lungs of cystic fibrosis (CF) patients, a process regulated by quorum-sensing molecules including N-(3-oxododecanoyl)-l-homoserine lactone (C12). C12 (10-100 µM) rapidly triggered events commonly associated with the intrinsic apoptotic pathway in JME (CF ΔF508CFTR, nasal surface) epithelial cells: depolarization of mitochondrial (mito) membrane potential (Δψ(mito)) and release of cytochrome C (cytoC) from mitos into cytosol and activation of caspases 3/7, 8 and 9. C12 also had novel effects on the endoplasmic reticulum (release of both Ca(2+) and ER-targeted GFP and oxidized contents into the cytosol). Effects began within 5 min and were complete in 1-2 h. C12 caused similar activation of caspases and release of cytoC from mitos in Calu-3 (wtCFTR, bronchial gland) cells, showing that C12-triggered responses occurred similarly in different airway epithelial types. C12 had nearly identical effects on three key aspects of the apoptosis response (caspase 3/7, depolarization of Δψ(mito) and reduction of redox potential in the ER) in JME and CFTR-corrected JME cells (adenoviral expression), showing that CFTR was likely not an important regulator of C12-triggered apoptosis in airway epithelia. Exposure of airway cultures to biofilms from PAO1wt caused depolarization of Δψ(mito) and increases in Ca(cyto) like 10-50 µM C12. In contrast, biofilms from PAO1ΔlasI (C12 deficient) had no effect, suggesting that C12 from P. aeruginosa biofilms may contribute to accumulation of apoptotic cells that cannot be cleared from CF lungs. A model to explain the effects of C12 is proposed.

Caspase-mediated apoptosis of trophoblasts in term human placental villi is restricted to cytotrophoblasts and absent from the multinucleated syncytiotrophoblast

Human placental villi are surfaced by a multinucleated and terminally differentiated epithelium, the syncytiotrophoblast, with a subjacent layer of mononucleated cytotrophoblasts that can divide and fuse to replenish the syncytiotrophoblast. The objectives of this study were i) to develop an approach to definitively identify and distinguish cytotrophoblasts from the syncytiotrophoblast, ii) to unambiguously determine the relative susceptibility of villous cytotrophoblasts and syncytiotrophoblast to constitutive and stress-induced apoptosis mediated by caspases, and iii) to understand the progression of apoptosis in villous trophoblasts. Confocal microscopy with co-staining for E-cadherin and DNA allowed us to clearly distinguish the syncytiotrophoblast from cytotrophoblasts and identified that many cytotrophoblasts are deeply interdigitated into the syncytiotrophoblast. Staining for specific markers of caspase-mediated apoptosis indicate that apoptosis occurs readily in cytotrophoblasts but is remarkably inhibited in the syncytiotrophoblast. To determine if an apoptotic cell or cell fragment was from a cytotrophoblast or syncytiotrophoblast, we found co-staining with E-cadherin along with a marker for apoptosis was essential: in the absence of E-cadherin staining, apoptotic cytotrophoblasts would easily be mistaken as representing localized regions of apoptosis in the syncytiotrophoblast. Regions with perivillous fibrin-containing fibrinoid contain the remnants of trophoblast apoptosis, and we propose this apoptosis occurs only after physical isolation of a region of the syncytium from the main body of the syncytium. We propose models for the progression of apoptosis in villous cytotrophoblasts and for why caspase-mediated apoptosis does not occur within the syncytium of placental villi.

Morphological classification of plant cell deaths

Programmed cell death (PCD) is an integral part of plant development and of responses to abiotic stress or pathogens. Although the morphology of plant PCD is, in some cases, well characterised and molecular mechanisms controlling plant PCD are beginning to emerge, there is still confusion about the classification of PCD in plants. Here we suggest a classification based on morphological criteria. According to this classification, the use of the term 'apoptosis' is not justified in plants, but at least two classes of PCD can be distinguished: vacuolar cell death and necrosis. During vacuolar cell death, the cell contents are removed by a combination of autophagy-like process and release of hydrolases from collapsed lytic vacuoles. Necrosis is characterised by early rupture of the plasma membrane, shrinkage of the protoplast and absence of vacuolar cell death features. Vacuolar cell death is common during tissue and organ formation and elimination, whereas necrosis is typically found under abiotic stress. Some examples of plant PCD cannot be ascribed to either major class and are therefore classified as separate modalities. These are PCD associated with the hypersensitive response to biotrophic pathogens, which can express features of both necrosis and vacuolar cell death, PCD in starchy cereal endosperm and during self-incompatibility. The present classification is not static, but will be subject to further revision, especially when specific biochemical pathways are better defined.

Autophagy protects against aminochrome-induced cell death in substantia nigra-derived cell line

Aminochrome, the precursor of neuromelanin, has been proposed to be involved in the neurodegeneration neuromelanin-containing dopaminergic neurons in Parkinson's disease. We aimed to study the mechanism of aminochrome-dependent cell death in a cell line derived from rat substantia nigra. We found that aminochrome (50μM), in the presence of NAD(P)H-quinone oxidoreductase, EC 1.6.99.2 (DT)-diaphorase inhibitor dicoumarol (DIC) (100μM), induces significant cell death (62 ± 3%; p < 0.01), increase in caspase-3 activation (p < 0.001), release of cytochrome C, disruption of mitochondrial membrane potential (p < 0.01), damage of mitochondrial DNA, damage of mitochondria determined with transmission electron microscopy, a dramatic morphological change characterized as cell shrinkage, and significant increase in number of autophagic vacuoles. To determine the role of autophagy on aminochrome-induced cell death, we incubated the cells in the presence of vinblastine and rapamycin. Interestingly, 10μM vinblastine induces a 5.9-fold (p < 0.001) and twofold (p < 0.01) significant increase in cell death when the cells were incubated with 30μM aminochrome in the absence and presence of DIC, respectively, whereas 10μM rapamycin preincubated 24 h before addition of 50μM aminochrome in the absence and the presence of 100μM DIC induces a significant decrease (p < 0.001) in cell death. In conclusion, autophagy seems to be an important protective mechanism against two different aminochrome-induced cell deaths that initially showed apoptotic features. The cell death induced by aminochrome when DT-diaphorase is inhibited requires activation of mitochondrial pathway, whereas the cell death induced by aminochrome alone requires inhibition of autophagy-dependent degrading of damaged organelles and recycling through lysosomes.