Medical Biology - Research Publications

Permanent URI for this collection

Search Results

Now showing 1 - 10 of 52
  • Item
    Thumbnail Image
    Cell death and thymic tolerance
    Daley, SR ; Teh, C ; Hu, DY ; Strasser, A ; Gray, DHD (WILEY, 2017-05)
    The differentiation of hematopoietic precursors into the many functionally distinct T-cell types produced by the thymus is a complex process. It proceeds through a series of stages orchestrated by a variety of thymic microenvironments that shape the T-cell developmental processes. Numerous cytokine and cell surface receptors direct thymocyte differentiation but the primary determinant of cell fate is the engagement of the T-cell antigen receptor (TCR). The strength of the TCR signal and the maturation stage of the thymocyte receiving it can direct the various differentiation programs or, alternatively, end the process by inducing cell death. The regulation of thymocyte death is critical for the efficiency of thymic T-cell differentiation and the preservation of immune tolerance. A detailed knowledge of mechanisms that eliminate thymocytes from the T-cell repertoire is essential to understand the "logic" of T-cell selection in the thymus. This review focuses on the central role of the BCL-2 family of proteins in the apoptotic checkpoints that punctuate thymocyte differentiation and the consequences of defects in these processes.
  • Item
    Thumbnail Image
    Role of proapoptotic BH3-only proteins in Listeria monocytogenes infection
    Margaroli, C ; Oberle, S ; Lavanchy, C ; Scherer, S ; Rosa, M ; Strasser, A ; Pellegrini, M ; Zehn, D ; Acha-Orbea, H ; Ehirchiou, D (WILEY-BLACKWELL, 2016-06)
    The ability of pathogens to influence host cell survival is a crucial virulence factor. Listeria monocytogenes (Lm) infection is known to be associated with severe apoptosis of hepatocytes and spleen cells. This impairs host defense mechanisms and thereby facilitates the spread of intracellular pathogens. The general mechanisms of apoptosis elicited by Lm infection are understood, however, the roles of BH3-only proteins during primary Lm infection have not been examined. To explore the roles of BH3-only proteins in Lm-induced apoptosis, we studied Listeria infections in mice deficient in Bim, Bid, Noxa or double deficient in BimBid or BimNoxa. We found that BimNoxa double knockout mice were highly resistant to high-dose challenge with Listeria. Decreased bacterial burden and decreased host cell apoptosis were found in the spleens of these mice. The ability of the BH3-deficient mice to clear bacterial infection more efficiently than WT was correlated with increased concentrations of ROS, neutrophil extracellular DNA trap release and downregulation of TNF-α. Our data show a novel pathway of infection-induced apoptosis that enhances our understanding of the mechanism by which BH3-only proteins control apoptotic host cell death during Listeria infection.
  • Item
    Thumbnail Image
    Loss of PUMA (BBC3) does not prevent thrombocytopenia caused by the loss of BCL-XL (BCL2L1)
    Delbridge, ARD ; Chappaz, S ; Ritchie, ME ; Kile, BT ; Strasser, A ; Grabow, S (WILEY, 2016-09)
    Apoptosis is required to maintain tissue homeostasis in multicellular organisms. Platelets, the anucleate cells that are essential for blood clotting, are a prime example. Their brief life span in the circulation is regulated by the intrinsic apoptosis pathway. Pro-survival BCL-XL (also termed BCL2L1) is essential for platelet viability. It functions to restrain the pro-apoptotic BCL-2 family members BAK (also termed BAK1) and BAX, the essential mediators of intrinsic apoptosis. Genetic deletion or pharmacological inhibition of BCL-XL results in thrombocytopenia. Conversely, deletion of BAK in platelets doubles their circulating life span. However, what triggers platelet apoptosis in vivo remains unclear. The pro-apoptotic BH3-only proteins are essential for initiating apoptosis in nucleated cells, and there is some evidence to suggest they also play a role in platelet biology. We investigated whether PUMA (also termed BBC3), a potent BH3-only protein that can inhibit all pro-survival BCL-2 family members as well as directly activate BAX, regulates the death of platelets. Surprisingly, loss of PUMA had no impact on the loss of platelets caused by loss of BCL-XL. It therefore remains to be established whether other BH3-only proteins play a critical role in induction of apoptosis in platelets or whether their death is controlled solely by the interactions between BCL-XL with BAK and BAX.
  • Item
    Thumbnail Image
    CARD11 is dispensable for homeostatic responses and suppressive activity of peripherally induced FOXP3+ regulatory T cells
    Polichen, A ; Horikawa, K ; Milla, L ; Kofler, J ; Bouillet, P ; Belz, GT ; O'Reilly, LA ; Goodnow, CC ; Strasser, A ; Gray, DHD (WILEY, 2019-09)
    FOXP3+ regulatory T (Treg) cells are essential for immunological tolerance and immune homeostasis. Despite a great deal of interest in modulating their number and function for the treatment of autoimmune disease or cancer, the precise mechanisms that control the homeostasis of Treg cells remain unclear. We report a new ENU-induced mutant mouse, lack of costimulation (loco), with atopic dermatitis and Treg cell deficiency typical of Card11 loss-of-function mutants. Three distinct single nucleotide variants were found in the Card11 introns 2, 10 and 20 that cause the loss of CARD11 expression in these mutant mice. These mutations caused the loss of thymic-derived, Neuropilin-1+ (NRP1+ ) Treg cells in neonatal and adult loco mice; however, residual peripherally induced NRP1- Treg cells remained. These peripherally generated Treg cells could be expanded in vivo by the administration of IL-2:anti-IL-2 complexes, indicating that this key homeostatic signaling axis remained intact in CARD11-deficient Treg cells. Furthermore, these expanded Treg cells could mediate near-normal suppression of activated, conventional CD4+ T cells, suggesting that CARD11 is dispensable for Treg cell function. In addition to shedding light on the requirements for CARD11 in Treg cell homeostasis and function, these data reveal novel noncoding Card11 loss-of-function mutations that impair the expression of this critical immune-regulatory protein.
  • Item
    Thumbnail Image
    Molecular mechanisms of cell death: recommendations of the Nomenclature Committee on Cell Death 2018
    Galluzzi, L ; Vitale, I ; Aaronson, SA ; Abrams, JM ; Adam, D ; Agostinis, P ; Alnemri, ES ; Altucci, L ; Amelio, I ; Andrews, DW ; Annicchiarico-Petruzzelli, M ; Antonov, AV ; Arama, E ; Baehrecke, EH ; Barlev, NA ; Bazan, NG ; Bernassola, F ; Bertrand, MJM ; Bianchi, K ; Blagosklonny, MV ; Blomgren, K ; Borner, C ; Boya, P ; Brenner, C ; Campanella, M ; Candi, E ; Carmona-Gutierrez, D ; Cecconi, F ; Chan, FK-M ; Chandel, NS ; Cheng, EH ; Chipuk, JE ; Cidlowski, JA ; Ciechanover, A ; Cohen, GM ; Conrad, M ; Cubillos-Ruiz, JR ; Czabotar, PE ; D'Angiolella, V ; Dawson, TM ; Dawson, VL ; De laurenzi, V ; De Maria, R ; Debatin, K-M ; DeBerardinis, RJ ; Deshmukh, M ; Di Daniele, N ; Di Virgilio, F ; Dixit, VM ; Dixon, SJ ; Duckett, CS ; Dynlacht, BD ; El-Deiry, WS ; Elrod, JW ; Fimia, GM ; Fulda, S ; Garcia-Saez, AJ ; Garg, AD ; Garrido, C ; Gavathiotis, E ; Golstein, P ; Gottlieb, E ; Green, DR ; Greene, LA ; Gronemeyer, H ; Gross, A ; Hajnoczky, G ; Hardwick, JM ; Harris, IS ; Hengartner, MO ; Hetz, C ; Ichijo, H ; Jaattela, M ; Joseph, B ; Jost, PJ ; Juin, PP ; Kaiser, WJ ; Karin, M ; Kaufmann, T ; Kepp, O ; Kimchi, A ; Kitsis, RN ; Klionsky, DJ ; Knight, RA ; Kumar, S ; Lee, SW ; Lemasters, JJ ; Levine, B ; Linkermann, A ; Lipton, SA ; Lockshin, RA ; Lopez-Otin, C ; Lowe, SW ; Luedde, T ; Lugli, E ; MacFarlane, M ; Madeo, F ; Malewicz, M ; Malorni, W ; Manic, G ; Marine, J-C ; Martin, SJ ; Martinou, J-C ; Medema, JP ; Mehlen, P ; Meier, P ; Melino, S ; Miao, EA ; Molkentin, JD ; Moll, UM ; Munoz-Pinedo, C ; Nagata, S ; Nunez, G ; Oberst, A ; Oren, M ; Overholtzer, M ; Pagano, M ; Panaretakis, T ; Pasparakis, M ; Penninger, JM ; Pereira, DM ; Pervaiz, S ; Peter, ME ; Piacentini, M ; Pinton, P ; Prehn, JHM ; Puthalakath, H ; Rabinovich, GA ; Rehm, M ; Rizzuto, R ; Rodrigues, CMP ; Rubinsztein, DC ; Rudel, T ; Ryan, KM ; Sayan, E ; Scorrano, L ; Shao, F ; Shi, Y ; Silke, J ; Simon, H-U ; Sistigu, A ; Stockwell, BR ; Strasser, A ; Szabadkai, G ; Tait, SWG ; Tang, D ; Tavernarakis, N ; Thorburn, A ; Tsujimoto, Y ; Turk, B ; Vanden Berghe, T ; Vandenabeele, P ; Heiden, MGV ; Villunger, A ; Virgin, HW ; Vousden, KH ; Vucic, D ; Wagner, EF ; Walczak, H ; Wallach, D ; Wang, Y ; Wells, JA ; Wood, W ; Yuan, J ; Zakeri, Z ; Zhivotovsky, B ; Zitvogel, L ; Melino, G ; Kroemer, G (NATURE PUBLISHING GROUP, 2018-03)
    Over the past decade, the Nomenclature Committee on Cell Death (NCCD) has formulated guidelines for the definition and interpretation of cell death from morphological, biochemical, and functional perspectives. Since the field continues to expand and novel mechanisms that orchestrate multiple cell death pathways are unveiled, we propose an updated classification of cell death subroutines focusing on mechanistic and essential (as opposed to correlative and dispensable) aspects of the process. As we provide molecularly oriented definitions of terms including intrinsic apoptosis, extrinsic apoptosis, mitochondrial permeability transition (MPT)-driven necrosis, necroptosis, ferroptosis, pyroptosis, parthanatos, entotic cell death, NETotic cell death, lysosome-dependent cell death, autophagy-dependent cell death, immunogenic cell death, cellular senescence, and mitotic catastrophe, we discuss the utility of neologisms that refer to highly specialized instances of these processes. The mission of the NCCD is to provide a widely accepted nomenclature on cell death in support of the continued development of the field.
  • Item
    Thumbnail Image
    LUBAC prevents lethal dermatitis by inhibiting cell death induced by TNF, TRAIL and CD95L
    Taraborrelli, L ; Peltzer, N ; Montinaro, A ; Kupka, S ; Rieser, E ; Hartwig, T ; Sarr, A ; Darding, M ; Draber, P ; Haas, TL ; Akarca, A ; Marafioti, T ; Pasparakis, M ; Bertin, J ; Gough, PJ ; Bouillet, P ; Strasser, A ; Leverkus, M ; Silke, J ; Walczak, H (NATURE PUBLISHING GROUP, 2018-09-25)
    The linear ubiquitin chain assembly complex (LUBAC), composed of HOIP, HOIL-1 and SHARPIN, is required for optimal TNF-mediated gene activation and to prevent cell death induced by TNF. Here, we demonstrate that keratinocyte-specific deletion of HOIP or HOIL-1 (E-KO) results in severe dermatitis causing postnatal lethality. We provide genetic and pharmacological evidence that the postnatal lethal dermatitis in HoipE-KO and Hoil-1E-KO mice is caused by TNFR1-induced, caspase-8-mediated apoptosis that occurs independently of the kinase activity of RIPK1. In the absence of TNFR1, however, dermatitis develops in adulthood, triggered by RIPK1-kinase-activity-dependent apoptosis and necroptosis. Strikingly, TRAIL or CD95L can redundantly induce this disease-causing cell death, as combined loss of their respective receptors is required to prevent TNFR1-independent dermatitis. These findings may have implications for the treatment of patients with mutations that perturb linear ubiquitination and potentially also for patients with inflammation-associated disorders that are refractory to inhibition of TNF alone.
  • Item
    No Preview Available
    LUBAC is essential for embryogenesis by preventing cell death and enabling haematopoiesis
    Peltzer, N ; Darding, M ; Montinaro, A ; Draber, P ; Draberova, H ; Kupka, S ; Rieser, E ; Fisher, A ; Hutchinson, C ; Taraborrelli, L ; Hartwig, T ; Lafont, E ; Haas, TL ; Shimizu, Y ; Boiers, C ; Sarr, A ; Rickard, J ; Alvarez-Diaz, S ; Ashworth, MT ; Beal, A ; Enver, T ; Bertin, J ; Kaiser, W ; Strasser, A ; Silke, J ; Bouillet, P ; Walczak, H (NATURE PUBLISHING GROUP, 2018-05-03)
    The linear ubiquitin chain assembly complex (LUBAC) is required for optimal gene activation and prevention of cell death upon activation of immune receptors, including TNFR1 1 . Deficiency in the LUBAC components SHARPIN or HOIP in mice results in severe inflammation in adulthood or embryonic lethality, respectively, owing to deregulation of TNFR1-mediated cell death2-8. In humans, deficiency in the third LUBAC component HOIL-1 causes autoimmunity and inflammatory disease, similar to HOIP deficiency, whereas HOIL-1 deficiency in mice was reported to cause no overt phenotype9-11. Here we show, by creating HOIL-1-deficient mice, that HOIL-1 is as essential for LUBAC function as HOIP, albeit for different reasons: whereas HOIP is the catalytically active component of LUBAC, HOIL-1 is required for LUBAC assembly, stability and optimal retention in the TNFR1 signalling complex, thereby preventing aberrant cell death. Both HOIL-1 and HOIP prevent embryonic lethality at mid-gestation by interfering with aberrant TNFR1-mediated endothelial cell death, which only partially depends on RIPK1 kinase activity. Co-deletion of caspase-8 with RIPK3 or MLKL prevents cell death in Hoil-1-/- (also known as Rbck1-/-) embryos, yet only the combined loss of caspase-8 with MLKL results in viable HOIL-1-deficient mice. Notably, triple-knockout Ripk3-/-Casp8-/-Hoil-1-/- embryos die at late gestation owing to haematopoietic defects that are rescued by co-deletion of RIPK1 but not MLKL. Collectively, these results demonstrate that both HOIP and HOIL-1 are essential LUBAC components and are required for embryogenesis by preventing aberrant cell death. Furthermore, they reveal that when LUBAC and caspase-8 are absent, RIPK3 prevents RIPK1 from inducing embryonic lethality by causing defects in fetal haematopoiesis.
  • Item
    No Preview Available
    A type III effector antagonizes death receptor signalling during bacterial gut infection
    Pearson, JS ; Giogha, C ; Ong, SY ; Kennedy, CL ; Kelly, M ; Robinson, KS ; Lung, TWF ; Mansell, A ; Riedmaier, P ; Oates, CVL ; Zaid, A ; Muehlen, S ; Crepin, VF ; Marches, O ; Ang, C-S ; Williamson, NA ; O'Reilly, LA ; Bankovacki, A ; Nachbur, U ; Infusini, G ; Webb, AI ; Silke, J ; Strasser, A ; Frankel, G ; Hartland, EL (NATURE PUBLISHING GROUP, 2013-09-12)
    Successful infection by enteric bacterial pathogens depends on the ability of the bacteria to colonize the gut, replicate in host tissues and disseminate to other hosts. Pathogens such as Salmonella, Shigella and enteropathogenic and enterohaemorrhagic (EPEC and EHEC, respectively) Escherichia coli use a type III secretion system (T3SS) to deliver virulence effector proteins into host cells during infection that promote colonization and interfere with antimicrobial host responses. Here we report that the T3SS effector NleB1 from EPEC binds to host cell death-domain-containing proteins and thereby inhibits death receptor signalling. Protein interaction studies identified FADD, TRADD and RIPK1 as binding partners of NleB1. NleB1 expressed ectopically or injected by the bacterial T3SS prevented Fas ligand or TNF-induced formation of the canonical death-inducing signalling complex (DISC) and proteolytic activation of caspase-8, an essential step in death-receptor-induced apoptosis. This inhibition depended on the N-acetylglucosamine transferase activity of NleB1, which specifically modified Arg 117 in the death domain of FADD. The importance of the death receptor apoptotic pathway to host defence was demonstrated using mice deficient in the FAS signalling pathway, which showed delayed clearance of the EPEC-like mouse pathogen Citrobacter rodentium and reversion to virulence of an nleB mutant. The activity of NleB suggests that EPEC and other attaching and effacing pathogens antagonize death-receptor-induced apoptosis of infected cells, thereby blocking a major antimicrobial host response.
  • Item
    No Preview Available
    CAML regulates Bim-dependent thymocyte death
    Edgar, CE ; Lindquist, LD ; McKean, DL ; Strasser, A ; Bram, RJ (NATURE PUBLISHING GROUP, 2010-10)
    Appropriate control of apoptosis during T lymphocyte differentiation is critical for destruction of T cells bearing potentially autoreactive or useless immuno-receptors and for survival of those T cells bearing antigen receptors that may recognize foreign proteins. Despite the well-established importance of thymocyte survival, the exact signals regulating thymocyte apoptosis have not been fully elucidated. Here, we show that thymocytes lacking the endoplasmic reticulum protein calcium-modulating cyclophilin ligand (CAML) failed to undergo normal T-cell development and exhibited dramatically increased rates of apoptosis. In vitro, CAML-deficient thymocytes accumulated high levels of reactive oxygen species (ROS) and underwent abnormally accelerated death in response to several cytotoxic stimuli, including treatment with etoposide, cytokine deprivation, or Fas ligation. Although neither p53 deletion nor loss of Fas rescued the survival and continued development of CAML-deficient thymocytes, removal of the pro-apoptotic BH3-only Bcl-2 family member Bim significantly restored their survival. This work reveals CAML to be a critically important regulator of ROS- and Bim-dependent thymocyte death.
  • Item
    No Preview Available
    Individual and overlapping roles of BH3-only proteins Bim and Bad in apoptosis of lymphocytes and platelets and in suppression of thymic lymphoma development
    Kelly, PN ; White, MJ ; Goschnick, MW ; Fairfax, KA ; Tarlinton, DM ; Kinkel, SA ; Bouillet, P ; Adams, JM ; Kile, BT ; Strasser, A (NATURE PUBLISHING GROUP, 2010-10)
    BH3-only proteins, such as Bim and Bad, contribute to tissue homeostasis by initiating apoptosis in a cell type- and stimulus-specific manner. Loss of Bim provokes lymphocyte accumulation in vivo and renders lymphocytes more resistant to diverse apoptotic stimuli and Bad has been implicated in the apoptosis of haematopoietic cells upon cytokine deprivation. To investigate whether their biological roles in apoptosis overlap, we generated mice lacking both Bim and Bad and compared their haematopoietic phenotype with that of the single-knockout and wild-type (wt) animals. Unexpectedly, bad(-/-) mice had excess platelets due to prolonged platelet life-span. The bim(-/-)bad(-/-) mice were anatomically normal and fertile. Their haematopoietic phenotype resembled that of bim(-/-) mice but lymphocytes were slightly more elevated in their lymph nodes. Although resting B and T lymphocytes from bim(-/-)bad(-/-) and bim(-/-) animals displayed similar resistance to diverse apoptotic stimuli, mitogen activated bim(-/-)bad(-/-) B cells were more refractory to cytokine deprivation. Moreover, combined loss of Bim and Bad-enhanced survival of thymocytes after DNA damage and accelerated development of γ-irradiation-induced thymic lymphoma. Unexpectedly, their cooperation in the thymus depended upon thymocyte-stromal interaction. Collectively, these results show that Bim and Bad can cooperate in the apoptosis of thymocytes and activated B lymphocytes and in the suppression of thymic lymphoma development.