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Grillot DA, Merino R, Pena JC, Fanslow WC, Finkelman FD, Thompson CB, Nunez G. bcl-x exhibits regulated expression during B cell development and activation and modulates lymphocyte survival in transgenic mice. J Exp Med 1996; 183:381-91. [PMID: 8627151 PMCID: PMC2192442 DOI: 10.1084/jem.183.2.381] [Citation(s) in RCA: 154] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/31/2023] Open
Abstract
We have assessed during B cell development, the regulation and function of bcl-x, a member of the bcl-2 family of apoptosis regulatory genes. Here we show that Bcl-xL, a product of bcl-x, is expressed in pre-B cells but downregulated at the immature and mature stages of B cell development. Bcl-xL but not Bcl-2 is rapidly induced in peripheral B cells upon surface immunoglobulin M (IgM) cross-linking, CD40 signaling, or LPS stimulation. Transgenic mice that overexpressed Bcl-xL within the B cell lineage exhibited marked accumulation of peripheral B cells in lymphoid organs and enhanced survival of developing and mature B cells. B cell survival was further increased by simultaneous expression of bcl-xL and bcl-2 transgenes. These studies demonstrate that Bcl-2 and Bcl-xL are regulated differentially during B cell development and activation of mature B cells. Induction of Bcl-xL after signaling through surface IgM and CD40 appears to provide mature B cells with an additional protective mechanism against apoptotic signals associated with antigen-induced activation and proliferation.
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Grillot DA, Merino R, Núñez G. Bcl-XL displays restricted distribution during T cell development and inhibits multiple forms of apoptosis but not clonal deletion in transgenic mice. J Exp Med 1995; 182:1973-83. [PMID: 7500043 PMCID: PMC2192263 DOI: 10.1084/jem.182.6.1973] [Citation(s) in RCA: 146] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/25/2023] Open
Abstract
The survival of T lymphocytes is tightly controlled during development. Here, we show that Bcl-xL, a protein homologue of Bcl-2, is highly regulated in the thymus in a pattern different than that of Bcl-2. The maximum expression was in CD4+CD8+ thymocytes, a developmental stage where Bcl-2 is downregulated. To assess the role of Bcl-xL in thymocyte apoptosis, we generated mice overexpressing an E mu-bcl-x transgene within the T cell compartment. Constitutive expression of Bcl-xL resulted in accumulation of thymocytes and mature T cells in lymphoid organs. Thymocytes overexpressing Bcl-xL exhibited increased viability in vitro and were resistant to apoptosis induced by different signals, including glucocorticoid, gamma irradiation, calcium ionophore, and CD3 cross-linking. However, Bcl-xL was unable to block clonal deletion of thymocytes reactive with self-superantigens or H-Y antigen. These studies demonstrate that Bcl-2 and Bcl-xL, two functionally related proteins, are regulated independently during T cell development. In contrast to Bcl-2, which has been implicated in the maintenance of mature T cells, Bcl-xL appears to provide a survival signal for the maintenance of more immature CD4+CD8+ thymocytes before positive selection.
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Núñez G, Merino R, Grillot D, González-García M. Bcl-2 and Bcl-x: regulatory switches for lymphoid death and survival. IMMUNOLOGY TODAY 1994; 15:582-8. [PMID: 7848520 DOI: 10.1016/0167-5699(94)90221-6] [Citation(s) in RCA: 122] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/27/2023]
Abstract
The survival and death of lymphoid cells is under the control of a genetic program. Cell death is activated at different stages of development and serves to remove unnecessary and autoreactive lymphocytes, as well as to limit the immune response. The survival of cells is regulated by a set of genes that act as repressors of the cell death mechanism. Of these, bcl-2 and bcl-x exhibit a striking pattern of regulation during lymphoid maturation and can inhibit several forms of apoptotic cell death. Here, Gabriel Núñez and colleagues review recent developments in the field, particularly focusing on the role of the Bcl-2 and Bcl-x proteins in regulating lymphoid death and survival.
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Review |
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Packham G, White EL, Eischen CM, Yang H, Parganas E, Ihle JN, Grillot DA, Zambetti GP, Nuñez G, Cleveland JL. Selective regulation of Bcl-XL by a Jak kinase-dependent pathway is bypassed in murine hematopoietic malignancies. Genes Dev 1998; 12:2475-87. [PMID: 9716401 PMCID: PMC317092 DOI: 10.1101/gad.12.16.2475] [Citation(s) in RCA: 86] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/20/1998] [Accepted: 06/25/1998] [Indexed: 01/17/2023]
Abstract
Bcl-2 family proteins are key regulators of apoptosis and function as cell death antagonists (e.g., Bcl-2, Bcl-XL, and Mcl-1) or agonists (e.g., Bax, Bad, and Bak). Here we report that among the Bcl-2 family of proteins tested (Bcl-2, Bcl-XL, Mcl-1, Bax, Bad, and Bak), Bcl-XL was unique in that its protein levels were tightly regulated by hemopoietins in both immortal and primary myeloid progenitors. Investigating signaling pathways utilized by cytokine receptors established that the regulation of Bcl-XL protein levels is mediated by the Jak kinase pathway and is independent of other signaling effectors including STATs, PI-3' kinase, and Ras. Moreover, we provide the first direct evidence that Bcl-X is altered in cancer, because bcl-X expression was activated selectively by retroviral insertions in murine myeloid and T-cell hemopoietic malignancies. Tumors harboring bcl-X insertions had altered bcl-X RNAs, expressed elevated levels of Bcl-XL protein, and lacked the requirements for cytokines normally essential for cell survival. Finally, overexpression of Bcl-XL effectively protected IL-3-dependent myeloid cells from apoptosis following removal of trophic factors. Therefore, Bcl-XL functions as a key cytokine regulated anti-apoptotic protein in myelopoiesis and contributes to leukemia cell survival.
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Simonian PL, Grillot DA, Merino R, Nuñez G. Bax can antagonize Bcl-XL during etoposide and cisplatin-induced cell death independently of its heterodimerization with Bcl-XL. J Biol Chem 1996; 271:22764-72. [PMID: 8798452 DOI: 10.1074/jbc.271.37.22764] [Citation(s) in RCA: 81] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023] Open
Abstract
Bax, a member of the Bcl-2 family of proteins, has been shown to promote apoptosis while other members of the family, including Bcl-XL and Bcl-2, inhibit cell death induced by a variety of stimuli. The mechanism by which Bax promotes cell death is poorly understood. In the present report, we assessed the ability of Bax to antagonize the death repressor activity of Bcl-XL during chemotherapy-induced apoptosis in the lymphoid cell line, FL5.12. Expression of wild-type Bax countered the repressor activity of Bcl-XL against cell death mediated by VP-16 and cisplatin. We performed site-directed mutagenesis of the BH1, BH2, and BH3 homology regions in Bax to determine the ability of wild-type and mutant Bax to heterodimerize with Bcl-XL and to antagonize the protective effect of Bcl-XL against chemotherapy-induced apoptosis. Bax proteins expressing alanine substitutions of the highly conserved amino acids glycine 108 in BH1, tryptophan 151 and 158 in BH2, and glycine 67 and aspartic acid 68 in BH3 retained their ability to promote chemotherapy-induced cell death that was inhibited by Bcl-XL and to form heterodimers with Bcl-XL. Bax proteins containing deletions of the most highly conserved amino acids in BH1 (Delta102-112) and BH2 (Delta151-159) maintained the ability of Bax to antagonize the death repressor activity of Bcl-XL and to associate with Bcl-XL. However, Bax with BH3 deleted did not form heterodimers with Bcl-XL, but retained its ability to counter the death repressor activity of Bcl-XL. These results demonstrate that the conserved BH3, but not BH1 or BH2, homology region of Bax is necessary for its interaction with Bcl-XL in mammalian cells. Furthermore, our results indicate that Bax does not require BH1, BH2, BH3, or heterodimerization with Bcl-XL to counter the death repressor activity of Bcl-XL. Therefore, Bax can antagonize Bcl-XL during VP-16 and, in a lesser degree, during cisplatin-induced cell death independent of its heterodimerization with Bcl-XL.
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Rénia L, Marussig MS, Grillot D, Pied S, Corradin G, Miltgen F, Del Giudice G, Mazier D. In vitro activity of CD4+ and CD8+ T lymphocytes from mice immunized with a synthetic malaria peptide. Proc Natl Acad Sci U S A 1991; 88:7963-7. [PMID: 1680235 PMCID: PMC52425 DOI: 10.1073/pnas.88.18.7963] [Citation(s) in RCA: 74] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022] Open
Abstract
In previous work, a T-helper epitope was mapped within the circumsporozoite protein of the murine malaria parasite Plasmodium yoelii. A 21-mer synthetic peptide corresponding to this epitope (amino acid positions 59-79; referred to as Py1) induced a specific T-cell proliferation in BALB/c and C57BL/6 mice and provided help for the production of antibodies to peptides from the repetitive region, (Gln-Gly-Pro-Gly-Ala-Pro)n, of the P. yoelii circumsporozoite protein when mice were immunized with the Py1 peptide conjugated to the repetitive peptide. Experiments were then designed to study the in vitro antiparasite efficacy of T cells elicited in vivo by peptide immunization. T-cell activity was evaluated on cultured hepatic stages of P. yoelii. Peptide immunizations led to the preferential activation of CD8+ T cells in BALB/c mice and of both CD4+ and CD8+ T cells in C57BL/6 mice. Parasite elimination was mediated directly by these cells and did not seem to be dependent on lymphokine secretion. These data suggest that peptide-primed CD4+ T cells as well as CD8+ T cells could be cytolytic for the hepatic phase of malaria parasites. The fact that the same peptide could activate different lymphocyte populations, depending on the strain of mouse, highlights the importance of a better understanding of the fine mechanisms behind the immune responses to synthetic peptides being tested for malaria vaccine development.
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Solvason N, Wu WW, Kabra N, Lund-Johansen F, Roncarolo MG, Behrens TW, Grillot DA, Nunez G, Lees E, Howard M. Transgene expression of bcl-xL permits anti-immunoglobulin (Ig)-induced proliferation in xid B cells. J Exp Med 1998; 187:1081-91. [PMID: 9529324 PMCID: PMC2212200 DOI: 10.1084/jem.187.7.1081] [Citation(s) in RCA: 62] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/24/1997] [Revised: 01/29/1998] [Indexed: 11/04/2022] Open
Abstract
Mutations in the tyrosine kinase, Btk, result in a mild immunodeficiency in mice (xid). While B lymphocytes from xid mice do not proliferate to anti-immunoglobulin (Ig), we show here induction of the complete complement of cell cycle regulatory molecules, though the level of induction is about half that detected in normal B cells. Cell cycle analysis reveals that anti-Ig stimulated xid B cells enter S phase, but fail to complete the cell cycle, exhibiting a high rate of apoptosis. This correlated with a decreased ability to induce the anti-apoptosis regulatory protein, Bcl-xL. Ectopic expression of Bcl-xL in xid B cells permitted anti-Ig induced cell cycle progression demonstrating dual requirements for induction of anti-apoptotic proteins plus cell cycle regulatory proteins during antigen receptor mediated proliferation. Furthermore, our results link one of the immunodeficient traits caused by mutant Btk with the failure to properly regulate Bcl-xL.
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8
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Simonian PL, Grillot DA, Nuñez G. Bak can accelerate chemotherapy-induced cell death independently of its heterodimerization with Bcl-XL and Bcl-2. Oncogene 1997; 15:1871-5. [PMID: 9362454 DOI: 10.1038/sj.onc.1201350] [Citation(s) in RCA: 41] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
Bak has been shown to both promote apoptosis and to inhibit cell death while two other members of the Bcl-2 family of proteins, Bcl-XL and Bcl-2 delay apoptosis induced by various stimuli including chemotherapeutic agents. We generated clones with stable expression of Bak wild-type (wt) and Bak with its BH3 (delta78-86) domain deleted (deltaBH3) in FL5.12 cells or FL5.12 cells expressing either Bcl-XL or Bcl-2 to determine if Bak could accelerate apoptosis and antagonize the death repressor activity of Bcl-XL and Bcl-2 during chemotherapy-induced apoptosis. We found that Bak accelerated cell death in FL5.12 cells treated with etoposide, fluorouracil or taxol. In FL5.12 cells expressing Bcl-XL and Bak wt or Bak deltaBH3, both Bak wt or Bak deltaBH3 were able to antagonize the protective effect of Bcl-XL when treated with etoposide or fluorouracil. Bak wt or Bak deltaBH3 were also able to abrogate the protective effect of Bcl-2 in cells expressing Bcl-2 and Bak wt or Bak deltaBH3 when challenged by etoposide or fluorouracil. Immunoprecipitation studies revealed that deletion of BH3 disrupted heterodimerization between Bak and Bcl-XL and that both Bak wt and Bak deltaBH3 failed to interact with Bcl-2. These results demonstrate that Bak does not require its BH3 domain to promote apoptosis in stably transfected cells. Furthermore, Bak can accelerate chemotherapy-induced cell death independently of its heterodimerization with Bcl-XL and Bcl-2.
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Simonian PL, Grillot DA, Andrews DW, Leber B, Nuñez G. Bax homodimerization is not required for Bax to accelerate chemotherapy-induced cell death. J Biol Chem 1996; 271:32073-7. [PMID: 8943258 DOI: 10.1074/jbc.271.50.32073] [Citation(s) in RCA: 41] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023] Open
Abstract
Bax, a member of the Bcl-2 family of proteins, has been shown to accelerate apoptosis induced by growth factor withdrawal, gamma-irradiation, and the chemotherapeutic agent, etoposide. The mechanism by which Bax promotes apoptosis is poorly understood. Bax forms homodimers which have been suggested to act as accelerators or inducers of cell death. However, the requirement for homodimerization of Bax to promote cell death remains unclear. We performed site-directed mutagenesis of the BH1, BH2, and BH3 in Bax to determine the regions of Bax required for homodimerization and to define the role of Bax homodimers in cell death induced by chemotherapy drugs. Bax proteins expressing alanine substitutions of the highly conserved amino acids glycine 108 (G108) in BH1, tryptophan 158 (W158) in BH2, and glycine 67 and aspartic acid 68 (GD67-68) in BH3 as well as deletion of the most conserved amino acids in BH1 (Delta102-112) and BH2 (Delta151-159) and deletion of BH3 (Delta63-71) maintained their ability to accelerate chemotherapy-induced cell death. Immunoprecipitation studies revealed that Bax with deletions in BH1 and BH2 still associated with wild-type Bax while deletion of BH3 disrupted Bax homodimerization. These results demonstrate that Bax does not require the conserved regions of homology, BH1, BH2, or BH3, to accelerate chemotherapy-induced cell death. Furthermore, our results established BH3 as a region required for Bax homodimerization in mammalian cells and demonstrate that monomeric forms of Bax are active in accelerating cell death induced by chemotherapy agents.
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Del Giudice G, Grillot D, Rénia L, Müller I, Corradin G, Louis JA, Mazier D, Lambert PH. Peptide-primed CD4+ cells and malaria sporozoites. Immunol Lett 1990; 25:59-63. [PMID: 1704350 DOI: 10.1016/0165-2478(90)90092-5] [Citation(s) in RCA: 34] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Abstract
We have mapped a T cell epitope in the circumsporozoite (CS) protein of the murine malaria parasite, Plasmodium yoelii. A 21-mer synthetic peptide corresponding to the amino acid positions 59-79 (referred to as Py1), induced specific proliferation in BALB/c and C57BL/6 mice, and provided help for the production of antibodies to peptides from the repetitive region, (QGPGAP)n, of the same CS protein, when mice were immunized with the Py1 peptide conjugated to the repetitive peptide. Long-term CD3+CD4+CD8-TCR alpha beta+ T cell lines and clones were derived from both strains of mice. These lines and clones, that proliferated in an MHC-restricted fashion, did not recognize peptides from the homologous region of another murine malaria parasite, P. berghei. About 50% of these clones produced detectable amounts of IFN-gamma and IL-2, whereas the remaining produced IL-4, IL-5, and IL-6. In preliminary experiments, some of these clones specifically inhibited P. yoelii sporozoite development in vitro and conferred protection in vivo in passive transfer experiments. These findings show that heterogenous T cell populations are activated in mice upon immunization with a short peptide from the P. yoelii CS protein and that some of these cells could be active in the effector arm of the immune response against malaria sporozoites.
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Grillot D, Michel M, Müller I, Tougne C, Rènia L, Mazier D, Corradin G, Lambert PH, Louis JA, Del Guidice G. Immune responses to defined epitopes of the circumsporozoite protein of the murine malaria parasite, Plasmodium yoelii. Eur J Immunol 1990; 20:1215-22. [PMID: 1695152 DOI: 10.1002/eji.1830200604] [Citation(s) in RCA: 32] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Abstract
We have investigated the immunogenicity of defined sequences of the circumsporozoite (CS) protein of the murine malaria parasite, Plasmodium yoelii. A 21-ner synthetic peptide from the nonrepetitive region of the CS protein (position 59-79, referred to as Py1) induced T cell proliferative responses in H-2d and, to a lesser extent, in H-2b mice. Conversely, a synthetic peptide (referred to as Py4) consisting of four (QGPGAP) repeats of the P. yoelii CS protein, induced an antibody response only in H-2b mice. No antibody response was observed when the Py3 peptide, consisting of three (QGPGAP) repeats, was used as an immunogen. When cross-linked to the Py4 repetitive peptide, the Py1 sequence behaved as a T helper epitope allowing the production of anti-Py4 antibodies in H-2d mice. Several long-term T cell lines and clones specific for the nonrepetitive Py1 peptide were originated in vitro from both H-2d and H-2b mice. These lines and clones were CD4+ and proliferated in a major histocompatibility complex-restricted fashion. Furthermore, Py1-specific T cell lines and clones did not proliferate in the presence of synthetic peptides from an analogous region of another rodent malaria parasite, P. berghei, despite the high degree of homology existing in this sequence of the two CS proteins. Finally, supernatants from 7 out of 13 clones (from BALB/c mice) produced detectable amounts of interleukin 2 and interferon-gamma; whereas supernatants from the 4 clones from C57BL/6 and 2 from BALB/c mice contained detectable amounts of interleukin 5. These results show that functionally heterogenous CD4+ T cell populations, belonging to either TH1 or TH2 subset, are activated upon immunization of mice with the P. yoelii Py1 synthetic peptide. It is not yet known what differential role these CD4+ subsets play during the malaria infection or after immunization with different malaria T cell epitopes. This knowledge may have a particular impact in the design of effective subunit vaccines against malaria.
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Mazier D, Rénia L, Nussler A, Pied S, Marussig M, Goma J, Grillot D, Miltgen F, Drapier JC, Corradin G. Hepatic phase of malaria is the target of cellular mechanisms induced by the previous and the subsequent stages. A crucial role for liver nonparenchymal cells. Immunol Lett 1990; 25:65-70. [PMID: 1980910 DOI: 10.1016/0165-2478(90)90093-6] [Citation(s) in RCA: 28] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
Both the sporozoites and the erythrocytic stages can modulate the hepatic phase by cytokines, notably IFN-gamma, TNF and IL-6, either directly or as a result of a cascade of events, and by MHC-restricted and antibody-dependent cell-mediated cytotoxicity. The role played by CD8+ T cells in inducing protective immunity against pre-erythrocytic stages is clearly established. The potential interest of triggering peptide-primed CD4+ T cells has to be considered regarding protection. Indeed, CD4+ T cells induced by the non-repetitive part of the CS protein of Plasmodium yoelii are protective, by eliminating malaria from hepatocytes. The crucial role of the liver NPC has to be emphasized, their participation in TNF schizonticidal effect and in ADCC mechanisms being strongly supported by our data.
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Review |
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Nuñez G, Merino R, Simonian PL, Grillot DA. Regulation of lymphoid apoptosis by Bcl-2 and Bcl-XL. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 1996; 406:75-82. [PMID: 8910673 DOI: 10.1007/978-1-4899-0274-0_8] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
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Review |
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Grillot D, Valmori D, Lambert PH, Corradin G, Del Giudice G. Presentation of T-cell epitopes assembled as multiple-antigen peptides to murine and human T lymphocytes. Infect Immun 1993; 61:3064-7. [PMID: 7685741 PMCID: PMC280960 DOI: 10.1128/iai.61.7.3064-3067.1993] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023] Open
Abstract
Multiple-antigen peptide (MAP) constructs containing different T- and B-cell epitopes were assessed for their ability to be specifically recognized by murine and human T-cell clones. The different synthetic MAP constructs consisted of a malaria T-cell epitope or of a human universal tetanus toxin helper T-cell epitope collinearly synthesized with B-cell epitopes from the circumsporozoite proteins of different malaria parasites. All constructs were able to stimulate specifically T-cell clones. Interestingly, T-cell epitopes assembled as MAP constructs did not require processing for the specific stimulation of murine and human T-cell clones, as shown by retention of their stimulatory effect in the presence of glutaraldehyde-fixed antigen-presenting cells. However, processing was required for most of the synthetic constructs containing both T- and B-cell epitopes. Thus, the requirement for processing of these constructs seems to be dictated by the nature of the B-cell epitope present.
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Gross B, Hennuyer N, Bouchaert E, Rommens C, Grillot D, Mezdour H, Staels B. Generation and characterization of a humanized PPARδ mouse model. Br J Pharmacol 2012; 164:192-208. [PMID: 21426320 DOI: 10.1111/j.1476-5381.2011.01359.x] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/15/2023] Open
Abstract
BACKGROUND AND PURPOSE Humanized mice for the nuclear receptor peroxisome proliferator-activated receptor δ (PPARδ), termed PPARδ knock-in (PPARδ KI) mice, were generated for the investigation of functional differences between mouse and human PPARδ and as tools for early drug efficacy assessment. EXPERIMENTAL APPROACH Human PPARδ function in lipid metabolism was assessed at baseline, after fasting or when challenged with the GW0742 compound in mice fed a chow diet or high-fat diet (HFD). KEY RESULTS Analysis of PPARδ mRNA levels revealed a hypomorph expression of human PPARδ in liver, macrophages, small intestine and heart, but not in soleus and quadriceps muscles, white adipose tissue and skin. PPARδ KI mice displayed a small decrease of high-density lipoprotein-cholesterol whereas other lipid parameters were unaltered. Plasma metabolic parameters were similar in wild-type and PPARδ KI mice when fed chow or HFD, and following physiological (fasting) and pharmacological (GW0742 compound) activation of PPARδ. Gene expression profiling in liver, soleus muscle and macrophages showed similar gene patterns regulated by mouse and human PPARδ. The anti-inflammatory potential of human PPARδ was also similar to mouse PPARδ in liver and isolated macrophages. CONCLUSIONS AND IMPLICATIONS These data indicate that human PPARδ can compensate for mouse PPARδ in the regulation of lipid metabolism and inflammation. Overall, this novel PPARδ KI mouse model shows full responsiveness to pharmacological challenge and represents a useful tool for the preclinical assessment of PPARδ activators with species-specific activity.
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Research Support, Non-U.S. Gov't |
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Grillot D, Pessi A, Verdini AS, Lambert PH, Del Giudice G. Reduced antibody response to the repetitive sequence of the Plasmodium falciparum circumsporozoite protein in mice infected with Plasmodium yoelii blood forms. Med Microbiol Immunol 1990; 179:237-44. [PMID: 2082157 DOI: 10.1007/bf00192461] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
The immunogenicity of the carrier-free synthetic peptide, (NANP)40, from the repetitive region of the Plasmodium falciparum circumsporozoite (CS) protein was investigated in genetically responder mice (C57BL/6, H-2b) acutely infected with blood forms of the non-lethal murine malaria parasite, P. yoelii. As compared to non-infected mice, P. yoelii-infected C57BL/6 mice produced significantly lower titers of anti-(NANP)40 IgG antibodies. This decrease in the anti-(NANP)40 antibody response peaked with the peak of parasitemia, and involved all the IgG subclasses. Interestingly, this P. yoelii-mediated effect was evident both on the development of the antibody response to the (NANP)40 peptide, and on an already established anti-(NANP)40 antibody titer, as seen in mice immunized with the peptide 1 month before the infection. Since (NANP)n-based constructs are strongly envisaged as potential vaccines against falciparum malaria, these results might be important in the evaluation of the efficacy of these vaccine candidates, when they will be used in individuals living in endemic areas.
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Merino R, Grillot DA, Simonian PL, Muthukkumar S, Fanslow WC, Bondada S, Núñez G. Modulation of anti-IgM-induced B cell apoptosis by Bcl-xL and CD40 in WEHI-231 cells. Dissociation from cell cycle arrest and dependence on the avidity of the antibody-IgM receptor interaction. THE JOURNAL OF IMMUNOLOGY 1995. [DOI: 10.4049/jimmunol.155.8.3830] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
Abstract
The demise of B cell progenitors expressing functional IgM receptors for self appears to be the main mechanism by which B cell tolerance is accomplished. The genetic mechanisms that regulate the death process during this critical step of B cell development are still poorly understood. We have studied the regulation of apoptosis in WEHI-231 lymphoma cells after treatment with a panel of anti-IgM mAbs as an in vitro model of clonal B cell deletion. We showed that a product of bcl-x, Bcl-xL, can inhibit anti-IgM-induced apoptosis but not cell cycle arrest in a dose-dependent manner. Bcl-xL was efficient in protecting B cells from low but not high avidity anti-IgM mAbs. In contrast to that observed with Bcl-xL, CD40 stimulation was efficient in inhibiting both cell cycle arrest and apoptosis after IgM cross-linking regardless of the binding avidity of the anti-IgM Ab. Moreover, activation through IgM receptors but not CD40 induced up-regulation followed by rapid down-modulation of Bcl-xL. Thus, the capacity of Bcl-xL to modulate anti-IgM-induced apoptosis in WEHI-231 cells is highly dependent on the avidity of the Ab-IgM receptor interaction.
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Grillot DA, González-García M, Ekhterae D, Duan L, Inohara N, Ohta S, Seldin MF, Nuñez G. Genomic organization, promoter region analysis, and chromosome localization of the mouse bcl-x gene. THE JOURNAL OF IMMUNOLOGY 1997. [DOI: 10.4049/jimmunol.158.10.4750] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
Abstract
The bcl-x gene, a bcl-2 family member, is highly regulated during lymphoid development, and its expression modulates apoptosis in lymphoid and other cell populations. Several forms of bcl-x mRNAs with different biologic functions have been described in rodents and humans. In this study, we have determined the organization and promoter region of the mouse bcl-x gene in an effort to understand the molecular basis for the different bcl-x mRNA species identified in tissues. We show that mouse bcl-x maps to the distal mouse chromosome 2 at approximately 89 cM, and exhibits a three-exon structure with an untranslated first exon and a facultative first intron. The coding region of bcl-xL is generated by the juncture of exons II and III through a splicing reaction, whereas bcl-xS is generated by an alternatively utilized donor splice site located within exon II. Analysis of multiple cDNAs and primer extension experiments revealed major transcription initiation sites in brain and thymus within a GC-rich region, with multiple Sp1-binding motifs located upstream of exon I. Another promoter was mapped to a 57-bp region localized upstream of the translation initiation codon by transfection of reporter constructs into FL5.12 and K562 cell lines. The remarkable similarity between the genomic regions of bcl-2 and bcl-x suggests that these genes have evolved from a common ancestral gene or through gene duplication.
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Schneider TJ, Grillot D, Foote LC, Núñez GE, Rothstein TL. Bcl-x protects primary B cells against Fas-mediated apoptosis. THE JOURNAL OF IMMUNOLOGY 1997. [DOI: 10.4049/jimmunol.159.10.4834] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
Abstract
Primary murine splenic B cells are rendered sensitive or resistant to Fas-mediated apoptosis in a receptor-specific fashion. B cells stimulated though CD40 are Fas sensitive unless they also receive a signal though surface Ig that produces a state of resistance to Fas killing. Protection from Fas-mediated apoptosis takes time to develop and requires ongoing macromolecular synthesis; therefore, it appears to involve the induction and accumulation of one or more gene products. The role of Bcl-x was evaluated by examining the expression and function of this gene in primary B cells. bcl-x mRNA was induced by anti-IgM treatment of otherwise sensitive (CD40 ligand-treated) B cells. Bcl-x protein expression was induced by anti-IgM and appeared in a time frame that correlates well with the onset of anti-IgM-induced Fas resistance. Further, B cells from Bcl-x Tg mice were found to be resistant to Fas-mediated apoptosis. These results strongly suggest that the protection against Fas killing afforded by cross-linking surface Ig is mediated, at least in part, by an increase in Bcl-x.
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Mazier D, Rénia L, Pied S, Nussler A, Marussig M, Landau I, Miltgen F, Grillot D, Del Giudice G, Grau G. Hepatic stages of malaria: specific and non-specific factors inhibiting the development. PARASSITOLOGIA 1993; 35 Suppl:59-63. [PMID: 8233615] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 05/22/2023]
Abstract
Protection against pre-erythrocytic stages of malaria is possible, as demonstrated by the resistance obtained by immunizing with irradiated sporozoites. However, the involved mechanisms are more numerous and intricate than previously believed. Recently, the hepatic stage, rather than the sporozoite stage, has been seen as the target of immune attack.
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Benito A, Grillot D, Nuñez G, Fernández-Luna JL. Regulation and function of Bcl-2 during differentiation-induced cell death in HL-60 promyelocytic cells. THE AMERICAN JOURNAL OF PATHOLOGY 1995; 146:481-90. [PMID: 7856757 PMCID: PMC1869853] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 01/27/2023]
Abstract
Polymorphonuclear leukocytes are generated by differentiation of early myeloid precursors. Once fully differentiated, blood neutrophils are programmed to die rapidly and are removed by tissue macrophages. In normal myeloid cells, the death mechanism seems to be coupled to the differentiation pathway and is accomplished by a process termed apoptosis. In the present study, we have examined the role of Bcl-2 in the differentiation pathways of the promyelocytic cell line HL-60. Treatment of HL-60 with retinoic acid or phorbol ester, which induced neutrophil or macrophage-like cell differentiation, respectively, resulted in progressive loss of cellular viability and internucleosomal DNA degradation. In HL-60, differentiation and apoptosis were coupled to down-regulation of the Bcl-2 protein. Overexpression of Bcl-2 by gene transfer inhibited apoptosis triggered by terminal differentiation of HL-60. Yet, Bcl-2 did not alter the expression of surface markers or other phenotypic changes that are induced upon myeloid differentiation. In contrast to HL-60, another immature myeloid cell line, K562, did not produce Bcl-2 but expressed a related protein, Bcl-xL, that functions as a repressor of apoptotic cell death. K562 has been shown to be relatively resistant to a variety of apoptotic stimuli. Incubation of HL-60 and K562 with inhibitors of macromolecular synthesis induced apoptosis, which appeared earlier in HL-60 than in K562. Interestingly, Bcl-2 overexpression protected K562 cells from apoptosis induced by inhibitor of macromolecular synthesis but it had little or no effect on HL-60 cells. We conclude that although differentiation and apoptosis proceed simultaneously, they can be uncoupled by expression of Bcl-2. Down-regulation of Bcl-2 appears to be part of the differentiation pathway and may serve to facilitate the apoptotic response.
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Grillot DA, González-García M, Ekhterae D, Duan L, Inohara N, Ohta S, Seldin MF, Nuñez G. Genomic organization, promoter region analysis, and chromosome localization of the mouse bcl-x gene. JOURNAL OF IMMUNOLOGY (BALTIMORE, MD. : 1950) 1997; 158:4750-7. [PMID: 9144489] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Abstract
The bcl-x gene, a bcl-2 family member, is highly regulated during lymphoid development, and its expression modulates apoptosis in lymphoid and other cell populations. Several forms of bcl-x mRNAs with different biologic functions have been described in rodents and humans. In this study, we have determined the organization and promoter region of the mouse bcl-x gene in an effort to understand the molecular basis for the different bcl-x mRNA species identified in tissues. We show that mouse bcl-x maps to the distal mouse chromosome 2 at approximately 89 cM, and exhibits a three-exon structure with an untranslated first exon and a facultative first intron. The coding region of bcl-xL is generated by the juncture of exons II and III through a splicing reaction, whereas bcl-xS is generated by an alternatively utilized donor splice site located within exon II. Analysis of multiple cDNAs and primer extension experiments revealed major transcription initiation sites in brain and thymus within a GC-rich region, with multiple Sp1-binding motifs located upstream of exon I. Another promoter was mapped to a 57-bp region localized upstream of the translation initiation codon by transfection of reporter constructs into FL5.12 and K562 cell lines. The remarkable similarity between the genomic regions of bcl-2 and bcl-x suggests that these genes have evolved from a common ancestral gene or through gene duplication.
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Comparative Study |
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Benito A, Silva M, Grillot D, Nuñez G, Fernández-Luna JL. Apoptosis induced by erythroid differentiation of human leukemia cell lines is inhibited by Bcl-XL. Blood 1996; 87:3837-43. [PMID: 8611710] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/31/2023] Open
Abstract
The induction of tumor cell differentiation represents an attractive strategy for the treatment of a wide range of malignancies. Differentiation of HL-60 promyelocytic leukemia cells towards neutrophils or monocytes has been shown to induce apoptotic cell death, which is inhibited by bcl-2 over-expression. However, the role of the bcl-2 gene family during erythroid differentiation of human leukemia cells remains unknown. We found that human erythroleukemia (HEL) and K562, two leukemia cell lines that undergo erythroid differentiation do not express Bcl-2, but express Bcl-XL, a related protein that functions as an inhibitor of apoptosis. Differentiation of HEL or K562 cells with inducers of erythroid differentiation (hemin, retinoic acid, or transforming growth factor-beta) was accompanied by progressive cell death and degradation of genomic DNA into oligonucleosomal fragments. The loss of cellular viability was associated with downregulation of bcl-xL mRNA and protein. In contrast, the levels of Bax, another Bcl-2 family member implicated in apoptosis remained unaltered. Constitutive expression of Bcl-XL by gene transfer inhibited apoptosis triggered by erythroid differentiation of HEL K562 cells. Yet, Bcl-XL did not alter the expression of epsilon-globin, which is induced during erythoid differentiation of HEL and K562 cells, arguing that apoptosis and differentiation can be uncoupled by Bcl-XL. These results indicate that Bcl-XL acts as an antiapoptosis protein in leukemia cells that undergo erythroid differentiation and that downregulation of bcl-x is a component of the apoptotic response that is coupled to differentiation in human leukemia cells.
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Simonian PL, Grillot DA, Nuñez G. Bcl-2 and Bcl-XL can differentially block chemotherapy-induced cell death. Blood 1997; 90:1208-16. [PMID: 9242554] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023] Open
Abstract
Bcl-2 and its homologue Bcl-XL are expressed in a variety of tumors and their expression modulates the sensitivity of tumor cells to a wide spectrum of chemotherapeutic agents and gamma-irradiation. In the present report, we generated clones of FL5.12 lymphoid cells with similar levels of Bcl-2 and Bcl-XL using the Flag epitope to determine if these survival proteins could provide equivalent protection when challenged with chemotherapy or gamma-irradiation. Using four M-phase specific chemotherapeutic agents, Bcl-XL and Bcl-2 provided similar protection against vincristine and vinblastine whereas Bcl-XL afforded as much as 50% greater cell viability than Bcl-2 against etoposide and teniposide-induced cell death. In addition, Bcl-XL provided significantly greater cell viability than Bcl-2 against methotrexate, fluorouracil, and hydroxyurea, three S-phase specific agents. In apoptosis induced by gamma-irradiation and cisplatin, two antitumor treatments that are cell-cycle phase-nonspecific agents, both Bcl-XL and Bcl-2 conferred similar protection against gamma-irradiation, but Bcl-XL provided better protection than Bcl-2 against cisplatin. These results indicate that Bcl-XL and Bcl-2 confer a differential ability to protect against chemotherapy-induced cell death, which appears to be dependent on the molecular mechanism targeted by the drug rather than its cell-cycle phase specificity.
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Comparative Study |
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Merino R, Grillot DA, Simonian PL, Muthukkumar S, Fanslow WC, Bondada S, Núñez G. Modulation of anti-IgM-induced B cell apoptosis by Bcl-xL and CD40 in WEHI-231 cells. Dissociation from cell cycle arrest and dependence on the avidity of the antibody-IgM receptor interaction. JOURNAL OF IMMUNOLOGY (BALTIMORE, MD. : 1950) 1995; 155:3830-8. [PMID: 7561089] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Subscribe] [Scholar Register] [Indexed: 01/25/2023]
Abstract
The demise of B cell progenitors expressing functional IgM receptors for self appears to be the main mechanism by which B cell tolerance is accomplished. The genetic mechanisms that regulate the death process during this critical step of B cell development are still poorly understood. We have studied the regulation of apoptosis in WEHI-231 lymphoma cells after treatment with a panel of anti-IgM mAbs as an in vitro model of clonal B cell deletion. We showed that a product of bcl-x, Bcl-xL, can inhibit anti-IgM-induced apoptosis but not cell cycle arrest in a dose-dependent manner. Bcl-xL was efficient in protecting B cells from low but not high avidity anti-IgM mAbs. In contrast to that observed with Bcl-xL, CD40 stimulation was efficient in inhibiting both cell cycle arrest and apoptosis after IgM cross-linking regardless of the binding avidity of the anti-IgM Ab. Moreover, activation through IgM receptors but not CD40 induced up-regulation followed by rapid down-modulation of Bcl-xL. Thus, the capacity of Bcl-xL to modulate anti-IgM-induced apoptosis in WEHI-231 cells is highly dependent on the avidity of the Ab-IgM receptor interaction.
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