凋亡、自噬与程序性细胞坏死的信号关联网络

凋亡与程序性坏死是细胞程序性死亡的两种方式。研究表明这两种死亡方式之间可以互相抑制,而且程序性坏死可以在凋亡被抑制时作为一种备用死亡途径发挥作用。自噬是一种细胞自我保护的手段,又可以参与凋亡与坏死的进程,发挥促生存与促死亡的作用。本文介绍了一些对细胞凋亡、自噬与程序性坏死的分子机制的研究,并对它们之间的联系做出阐述。     

Pyroptosis is a drug target for prevention of adverse cardiac remodeling: The crosstalk between pyroptosis,apoptosis, and autophagy

Acute myocardial infarction (AMI) is one of the main reasons of cardiovascular disease-related death. The introduction of percutaneous coronary intervention to clinical practice dramatically decreased the mortality rate in AMI. Adverse cardiac remodeling is a serious problem in cardiology. An increase in the effectiveness of AMI treatment and prevention of adverse cardiac remodeling is difficult to achieve without understanding the mechanisms of reperfusion cardiac injury and cardiac remodeling. Inhibition of pyroptosis prevents the development of postinfarction and pressure overload-induced cardiac remodeling, and mitigates cardiomyopathy induced by diabetes and metabolic syndrome. Therefore, it is reasonable to hypothesize that the pyroptosis inhibitors may find a role in clinical practice for treatment of AMI and prevention of cardiac remodeling, diabetes and metabolic syndrome-triggered cardiomyopathy. It was demonstrated that pyroptosis interacts closely with apoptosis and autophagy. Pyroptosis could be inhibited by nucleotide-binding oligomerization domain-like receptor with a pyrin domain 3 inhibitors, caspase-1 inhibitors, microRNA, angiotensin-converting enzyme inhibitors, angiotensin Ⅱ receptor blockers, and traditional Chinese herbal medicines.     

Insights into inflammasome regulation: cellular,molecular, and pathogenic control of inflammasome activation

Maintenance of immune homeostasis is an intricate process wherein inflammasomes play a pivotal role by contributing to innate and adaptive immune responses. Inflammasomes are ensembles of adaptor proteins that can trigger a signal following innate sensing of pathogens or non-pathogens eventuating in the inductions of IL-1β and IL-18. These inflammatory cytokines substantially influence the antigen-presenting cell’s costimulatory functions and T helper cell differentiation, contributing to adaptive immunity. As acute and chronic disease conditions may accompany parallel tissue damage, we analyze the critical role of extracellular factors such as cytokines, amyloids, cholesterol crystals, etc., intracellular metabolites, and signaling molecules regulating inflammasome activation/inhibition. We develop an operative framework for inflammasome function and regulation by host cell factors and pathogens. While inflammasomes influence the innate and adaptive immune components’ interplay modulating the anti-pathogen adaptive immune response, pathogens may target inflammasome inhibition as a survival strategy. As trapped between health and diseases, inflammasomes serve as promising therapeutic targets and their modus operandi serves as a scientific rationale for devising better therapeutic strategies.

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Beclin 1 is involved in regulation of apoptosis and autophagy during replication of ectromelia virus in permissive L929 cells

Several reports have brought to light new and interesting findings on the involvement of autophagy and apoptosis in pathogenesis of viral and bacterial diseases, as well as presentation of foreign antigens. Our model studies focused on the involvement of apoptosis during replication of highly virulent Moscow strain of ectromelia virus (ECTV-MOS). Here, we show evidence that autophagy is induced during mousepox replication in a cell line. Fluorescence microscopy revealed increase of LC3 (microtubule-associated protein 1 light chain 3) aggregation in infected as opposed to non-infected control L929 cells. Furthermore, Western blot analysis showed that replication of ECTV-MOS in L929 cells led to the increase in LC3-II (marker of autophagic activity) expression. Beclin 1 strongly colocalized with extranuclear viral replication centers in infected cells, whereas expression of Bcl-2 decreased in those centers as shown by fluorescence microscopy. Loss of Beclin 1-Bcl-2 interaction may lead to autophagy in virus-infected L929 cells. To assess if Beclin 1 has a role in regulation of apoptosis during ECTV-MOS infection, we used small interfering RNA directed against beclin 1 following infection. Early and late apoptotic cells were analyzed by flow cytometry after AnnexinV and propidium iodide staining. Silencing of beclin 1 resulted in decreased percentage of early and late apoptotic cells in the late stage of ECTV-MOS infection in L929 cells. We conclude that Beclin 1 plays an important role in regulation of both, autophagy and apoptosis, during ECTV-MOS replication in L929 permissive cells.     

Cellular inhibitors of apoptosis proteins cIAP1 and cIAP2 are required for efficient caspase-1 activation by the inflammasome

Pathogen and danger recognition by the inflammasome activates inflammatory caspases that mediate inflammation and cell death. The cellular inhibitor of apoptosis proteins (cIAPs) function in apoptosis and innate immunity, but their role in modulating the inflammasome and the inflammatory caspases is unknown. Here we report that the cIAPs are critical effectors of the inflammasome and are required for efficient caspase-1 activation. cIAP1, cIAP2, and the adaptor protein TRAF2 interacted with caspase-1-containing complexes and mediated the activating nondegradative K63-linked polyubiquitination of caspase-1. Deficiency in cIAP1 (encoded by Birc2) or cIAP2 (Birc3) impaired caspase-1 activation after spontaneous or agonist-induced inflammasome assembly, and Birc2(-/-) or Birc3(-/-) mice or mice administered with an IAP antagonist had a dampened response to inflammasome agonists and were resistant to peritonitis. Our results describe a role for the cIAPs in innate immunity and further demonstrate the evolutionary conservation between cell death and inflammation mechanisms.     

自噬/苄氯素1调节因子1在自噬与凋亡中作用的研究进展

细胞凋亡(Ⅰ型程序性死亡)和自噬性细胞死亡(Ⅱ型程序性死亡)这2种细胞死亡方式可通过一些蛋白的相互作用而介导形成平衡对立状态.一方面,细胞凋亡由胱天蛋白酶(caspase,CASP)依赖性通路经内源性、外源性或内质网应激诱导途径予以控制,而死亡信号则可经这3种途径介导受损或感染细胞的清除[1-2].另一方面,细胞自噬由...     

Protective effect of rapamycin against acrylamide-induced hepatotoxicity: The associations between autophagy,apoptosis, and necroptosis

Acrylamide (ACRL) was demonstrated to induce hepatotoxicity and programmed cell death (PCD). Rapamycin (RAPA)-induced autophagy had been reported to limit the progression of hepatocellular injury in experimental models. This research was designed to study two death pathways involved in ACRL-induced hepatotoxicity and the modulating effect of RAPA on the resulting hepatic injury. Thirty-six adult male rats were divided into three groups: control group, ACRL-treated group (20 mg kg/day), and the last group co-treated with ACRL plus RAPA (0.5 mg kg/day). Drugs were administered for 21 days via oral gavage. Blood samples were collected to assess alanine aminotransferase (ALT) and aspartate aminotransferase (AST). Livers were dissected; parts were used for detection of superoxide dismutase (SOD) and malondialdehyde (MDA) tissue levels. Other parts were processed for hematoxylin and eosin, Masson's trichrome staining, immunostaining for microtubule-associated proteins 1A/1B light chain 3B (LC3), ubiquitin-binding protein (p62), caspase-3, and receptor-interacting protein kinase 1 (RIPK1). ACRL induced a significant elevation in ALT, AST, MDA levels, and reduction in the SOD level. ACRL also induced hepatocellular injury, fibrosis, and defective autophagy indicated by elevation of LC3 and p62 and increased p62/LC3 ratio. Moreover, it increased the apoptotic (caspase-3) and necroptotic (RIPK1) markers expression. RAPA significantly reduced liver enzymes, oxidative stress, fibrosis, and improved liver histology. Moreover, RAPA decreased p62/LC3 ratio indicated enhanced autophagy, and significantly reduced caspase-3 and RIPK1 expression. In conclusion, RAPA maintained autophagic activity which may save the hepatocytes from PCD and enhance cell viability.     

Neuronal apoptosis and autophagy cross talk in aging PS/APP mice, a model of Alzheimer's disease

Mechanisms of neuronal loss in Alzheimer’s disease (AD) are poorly understood. Here we show that apoptosis is a major form of neuronal cell death in PS/APP mice modeling AD-like neurodegeneration. Pyknotic neurons in adult PS/APP mice exhibited apoptotic changes, including DNA fragmentation, caspase-3 activation, and caspase-cleaved α-spectrin generation, identical to developmental neuronal apoptosis in wild-type mice. Ultrastructural examination using immunogold cytochemistry confirmed that activated caspase-3-positive neurons also exhibited chromatin margination and condensation, chromatin balls, and nuclear membrane fragmentation. Numbers of apoptotic profiles in both cortex and hippocampus of PS/APP mice compared with age-matched controls were twofold to threefold higher at 6 months of age and eightfold higher at 21 to 26 months of age. Additional neurons undergoing dark cell degeneration exhibited none of these apoptotic features. Activated caspase-3 and caspase-3-cleaved spectrin were abundant in autophagic vacuoles, accumulating in dystrophic neurites of PS/APP mice similar to AD brains. Administration of the cysteine protease inhibitor, leupeptin, promoted accumulation of autophagic vacuoles containing activated caspase-3 in axons of PS/APP mice and, to a lesser extent, in those of wild-type mice, implying that this pro-apoptotic factor is degraded by autophagy. Leupeptin-induced autophagic impairment increased the number of apoptotic neurons in PS/APP mice. Our findings establish apoptosis as a mode of neuronal cell death in aging PS/APP mice and identify the cross talk between autophagy and apoptosis, which influences neuronal survival in AD-related neurodegeneration.     

Impact of desloratadine and loratadine on the crosstalk between human keratinocytes and leukocytes: Implications for anti-inflammatory activity of antihistamines

BACKGROUND: Desloratadine is an H1-histamine antagonist which possesses additional anti-inflammatory properties through inhibition of leukocyte activation and reduction of ICAM-1 expression on mucosal epithelial cells. So far no studies have addressed the potential anti-inflammatory activities of desloratadine and loratadine on skin keratinocytes. OBJECTIVE: In this study the capacity of desloratadine and loratadine to counteract human keratinocyte activation by interferon-gamma (IFN-gamma) was analyzed. In particular, the chemokine release of kerationcytes and the crosstalk between keratinocytes and lymphocytes were examined. METHOD: Keratinocyte cultures established from normal skin of healthy donors were activated by IFN-gamma in the absence or presence of desloratadine and loratadine, and tested for the release of CCL5/RANTES, CXCL8/IL-8, CCL17/TARC and CXCL10/IP-10. Furthermore the supernatants of differentially stimulated keratinocytes were used for migration studies of human neutrophils, eosinophils and polarized Th1/Th2 clones. RESULTS: Desloratadine and loratadine inhibited the constitutive and IFN-gamma-induced release of CCL5, CXCL8 and CXCL10 from keratinocytes, while the low release of CCL17 remained unchanged. Furthermore the crosstalk between lymphocytes and keratinocytes was blocked as shown by a reduced capacity of desloratadine/loratadine-stimulated keratinocytes to attract human neutrophils, eosinophils and T cells. CONCLUSIONS: The results indicate that desloratadine has the capacity to block the IFN-gamma-induced activation of keratinocytes, and that it can thus exert important regulatory effects on cell-mediated immune responses in the skin. The rather high doses required for these effects argue for a topical application when trying to use desloratadine in epidermal inflammatory conditions.     

The mitochondrial F1-ATPase and the aging process

A progressive dysfunction of the mitochondrion probably plays a decisive role in the aging process. In the present hypothesis it is suggested that the functional defect specifically concerns the catalytic subunit of the mitochondrial F1-ATPase.This proposal is based on observations concerning two classical models of the aging process.

1. 1. The Werner syndrome of premature aging is autosomally recessive; meaning that this disorder — in analogy with other recessive inborn errors of metabolism — results from a single specific mutation, typically resulting in an enzyme defect.

2. 2. The strong association between the ATPase activity of the SV40 T-antigen and the process of cellular immortalization in vitro, suggests that the putative enzyme dysfunction could concern an ATPase.

The decrease with aging in the activity of the mitochondrial F1-ATPase — the main producer of ATP — could lay behind the progressive lack of homeostasis observed in senescence.     

Impact of HIV-1 infection on the feto-maternal crosstalk and consequences for pregnancy outcome and infant health

Adaptation of the maternal immune system to establish maternal/fetal equilibrium is required for a successful pregnancy. Viral infections, including HIV-1 infection, can alter this maternal/fetal equilibrium, with significant consequences for pregnancy outcome, including miscarriages, impaired fetal growth, and premature delivery. Furthermore, maternal HIV-1 infection has been shown to have a long-term impact on the developing fetal immune system also when the infant is not infected with the virus. In this review, we discuss the consequences of maternal HIV-1 infection and antiretroviral therapy on pregnancy outcome and the health of the uninfected HIV-1-exposed infant.     

NLRP3炎性小体激活调控机制研究新进展

NLRP3炎性小体是一种胞内多蛋白复合体,主要由NOD样受体家族成员NLRP3、接头蛋白ASC以及前体半胱天冬酶1(pro-caspase-1)组成,该炎性小体可以通过激活caspase-1促进促炎因子白细胞介素-1 beta(IL-1β)和IL-18的分泌以及细胞焦亡(pyroptosis)的形成.NLRP3炎性小体的激活在很多自身免疫性及自身炎症性疾病中扮演着重要的角色,因此,深入探究NLRP3炎性小体激活的调控机制可为NLRP3炎性小体相关疾病的治疗提供更多新的思路.     

The regulation of the ZBP1-NLRP3 inflammasome and its implications in pyroptosis,apoptosis, and necroptosis (PANoptosis)

ZBP1 has been characterized as a critical innate immune sensor of not only viral RNA products but also endogenous nucleic acid ligands. ZBP1 sensing of the Z-RNA produced during influenza virus infection induces cell death in the form of pyroptosis, apoptosis, and necroptosis (PANoptosis). PANoptosis is a coordinated cell death pathway that is driven through a multiprotein complex called the PANoptosome and enables crosstalk and co-regulation among these processes. During influenza virus infection, a key step in PANoptosis and PANoptosome assembly is the formation of the ZBP1-NLRP3 inflammasome. When Z-RNA is sensed, ZBP1 recruits RIPK3 and caspase-8 to activate the ZBP1-NLRP3 inflammasome. Several other host factors have been found to be important for ZBP1-NLRP3 inflammasome assembly, including molecules involved in the type I interferon signaling pathway and caspase-6. Additionally, influenza viral proteins, such as M2, NS1, and PB1-F2, have also been shown to regulate the ZBP1-NLRP3 inflammasome. This review explains the functions of ZBP1 and the mechanistic details underlying the activation of the ZBP1-NLRP3 inflammasome and the formation of the PANoptosome. Improved understanding of the ZBP1-NLRP3 inflammasome will direct the development of therapeutic strategies to target infectious and inflammatory diseases.     

Impact of crosslinking/riboflavin-UVA-photodynamic inactivation on viability,apoptosis and activation of human keratocytes in vitro

Riboflavin-UVA photodynamic inactivation is a potential treatment alternative in therapy resistant infectious keratitis. The purpose of our study was to determine the impact of riboflavin-UVA photodynamic inactivation on viability, apoptosis and activation of human keratocytes in vitro. Primary human keratocytes were isolated from human corneal buttons and cultured in DMEM/Ham''s F12 medium supplemented with 10% fetal calf serum. Keratocytes underwent UVA light illumination (375 nm) for 4.10 minutes (2 J/cm²) during exposure to different concentrations of riboflavin. Twenty-four hours after treatment, cell viability was evaluated photometrically, whereas apoptosis, CD34 and alpha-smooth muscle actin (α-SMA) expression were assessed using flow cytometry. We did not detect significant changes in cell viability, apoptosis, CD34 and α-SMA expression in groups only treated with riboflavin or UVA light. In the group treated with riboflavin-UVA-photodynamic inactivation, viability of keratocytes decreased significantly at 0.1% riboflavin (P<0.01) while the percentage of CD34 (P<0.01 for both 0.05% and 0.1% riboflavin) and alpha-SMA positive keratocytes (P<0.01 and P<0.05 for 0.05% and 0.1% riboflavin, respectively) increased significantly compared to the controls. There was no significant change in the percentage of apoptotic keratocytes compared to controls at any of the used riboflavin concentrations (P = 0.09 and P = 0.13). We concluded that riboflavin-UVA-photodynamic-inactivation decreases viability of myofibroblastic transformation and multipotent haematopoietic stem cell transformation; however, it does not have an impact on apoptosis of human keratocytes in vitro.