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1.
Nat Med ; 5(12): 1370-4, 1999 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-10581078

RESUMO

At present, little is known about the pathogenesis of acute virus-induced shock and pulmonary failure. A chief impediment in understanding the underlying disease mechanisms and developing treatment strategies has been the lack of a suitable animal model. This study describes a mouse model of virus-induced systemic shock and respiratory distress, and shows that blockade of the lymphotoxin beta receptor pathway reverses the disease.


Assuntos
Receptores do Fator de Necrose Tumoral/antagonistas & inibidores , Insuficiência Respiratória/terapia , Choque Séptico/terapia , Animais , Anticorpos Monoclonais/farmacologia , Modelos Animais de Doenças , Feminino , Humanos , Coriomeningite Linfocítica/imunologia , Coriomeningite Linfocítica/patologia , Coriomeningite Linfocítica/terapia , Receptor beta de Linfotoxina , Masculino , Camundongos , Camundongos Endogâmicos NZB , Insuficiência Respiratória/imunologia , Insuficiência Respiratória/patologia , Choque Séptico/imunologia , Choque Séptico/patologia , Transdução de Sinais , Fatores de Tempo
2.
J Exp Med ; 184(5): 1999-2006, 1996 Nov 01.
Artigo em Inglês | MEDLINE | ID: mdl-8920886

RESUMO

For more than a decade, the biological roles and the apparent redundancy of the cytokines tumor necrosis factor (TNF) and lymphotoxin (LT) have been debated. LT alpha exists in its soluble form as a homotrimer, which like TNF only binds the TNF receptors, TNF-R55 or TNF-R75. The cell surface form of LT exists as a heteromer of LT alpha and LT beta subunits and this complex specifically binds the LT beta receptor (LT beta-R). To discriminate the functions of the LT and TNF systems, soluble LT beta-R-immunoglobulin (Ig) or TNF-R-Ig fusion proteins were introduced into embryonic circulation by injecting pregnant mice. Exposure to LT beta-R-Ig during gestation disrupted lymph node development and splenic architecture in the progeny indicating that both effects are mediated by the surface LT alpha/beta complex. These data are the first to identify a cell surface ligand involved in immune organ morphogenesis. Moreover, they unambiguously discriminate the functions of the various TNF/LT ligands, provide a unique model to study compartmentalization of immune responses and illustrate the generic utility of receptor-Ig fusion proteins for dissecting/ordering ontogenetic events in the absence of genetic modifications.


Assuntos
Membrana Celular/metabolismo , Tecido Linfoide/embriologia , Linfotoxina-alfa/metabolismo , Proteínas de Membrana/metabolismo , Animais , Imunoglobulina G/farmacologia , Linfonodos/embriologia , Receptor beta de Linfotoxina , Camundongos , Camundongos Endogâmicos BALB C , Morfogênese , Nódulos Linfáticos Agregados/embriologia , Receptores do Fator de Necrose Tumoral/imunologia , Receptores do Fator de Necrose Tumoral/metabolismo , Proteínas Recombinantes de Fusão/farmacologia , Baço/embriologia , Fator de Necrose Tumoral alfa/metabolismo
3.
J Exp Med ; 190(5): 629-38, 1999 Sep 06.
Artigo em Inglês | MEDLINE | ID: mdl-10477548

RESUMO

Although several cytokines, including tumor necrosis factor (TNF), can promote the growth of dendritic cells (DCs) in vitro, the cytokines that naturally regulate DC development and function in vivo have not been well defined. Here, we report that membrane lymphotoxin (LT), instead of TNF, regulates the migration of DCs in the spleen. LTalpha(-/-) mice, lacking membrane LTalpha/beta and LTalpha(3), show markedly reduced numbers of DCs in the spleen. Unlike wild-type mice and TNF(-/-) mice that have densely clustered DCs in the T cell zone and around the marginal zone, splenic DCs in LTalpha(-/-) mice are randomly distributed. The reduced number of DCs in lymphoid tissues of LTalpha(-/-) mice is associated with an increased number of DCs in nonlymphoid tissues. The number of splenic DCs in LTalpha(-/-) mice is restored when additional LT-expressing cells are provided. Blocking membrane LTalpha/beta in wild-type mice markedly diminishes the accumulation of DCs in lymphoid tissues. These data suggest that membrane LT is an essential ligand for the presence of DCs in the spleen. Mice deficient in TNF receptor, which is the receptor for both soluble LTalpha(3) and TNF-alpha(3) trimers, have normal numbers of DCs. However, LTbetaR(-/-) mice show reduced numbers of DCs, similar to the mice lacking membrane LT alpha/beta. Taken together, these results support the notion that the signaling via LTbetaR by membrane LTalpha/beta is required for the presence of DCs in lymphoid tissues.


Assuntos
Células Dendríticas/imunologia , Células Dendríticas/fisiologia , Tecido Linfoide/citologia , Tecido Linfoide/imunologia , Linfotoxina-alfa/fisiologia , Animais , Células da Medula Óssea/imunologia , Contagem de Células , Movimento Celular/imunologia , Movimento Celular/fisiologia , Feminino , Teste de Cultura Mista de Linfócitos , Receptor beta de Linfotoxina , Linfotoxina-alfa/genética , Masculino , Camundongos , Camundongos Endogâmicos C57BL , Camundongos Knockout , Camundongos Transgênicos , Fenótipo , Receptores do Fator de Necrose Tumoral/deficiência , Receptores do Fator de Necrose Tumoral/genética , Receptores do Fator de Necrose Tumoral/fisiologia , Transdução de Sinais , Solubilidade , Baço/citologia , Baço/imunologia , Fator de Necrose Tumoral alfa/deficiência , Fator de Necrose Tumoral alfa/genética , Fator de Necrose Tumoral alfa/fisiologia
4.
J Exp Med ; 187(7): 997-1007, 1998 Apr 06.
Artigo em Inglês | MEDLINE | ID: mdl-9529316

RESUMO

The transfer of lymphocytes into severe combined immunodeficiency (SCID) mice induces a series of histological changes in the spleen, including the appearance of mature follicular dendritic cells (FDCs). Studies were undertaken to clarify the role of lymphotoxin (LT) in this process. The results show that SCID mice have a small and partially differentiated white pulp containing marginal zone and interdigitating dendritic cells, but lacking FDCs. Transferred spleen cells can segregate into T and B cell areas shortly after their injection to SCID mice. This ability is dependent on signaling through LT-beta receptor (LT-betaR), since blocking ligand-receptor interaction in recipient SCID mice ablates the capacity of the transferred cells to segregate. A week after lymphocyte transfer, host-derived FDCs appeared in the reconstituted SCID mice. This induction of FDCs is dependent on LT-betaR signaling by B cells since LT-alpha-/- B cells are incapable of inducing development of FDCs in SCID mice, even after cotransfer of LT-alpha+/+ T cells. Therefore, LT plays at least two discrete roles in splenic organization. First, it appears that LT induces the differentiation of the white pulp to create sites for lymphocyte segregation. Second, LT expression by B cells drives the maturation of FDCs and the organization of B cell follicles.


Assuntos
Linfócitos B/fisiologia , Células Dendríticas/metabolismo , Linfotoxina-alfa/fisiologia , Baço/fisiologia , Animais , Linfócitos B/metabolismo , Diferenciação Celular/fisiologia , Regulação da Expressão Gênica no Desenvolvimento/genética , Imuno-Histoquímica , Receptor beta de Linfotoxina , Camundongos , Camundongos SCID , Microscopia Confocal , Fenótipo , Receptores do Fator de Necrose Tumoral/metabolismo , Transdução de Sinais/fisiologia , Baço/citologia , Linfócitos T/metabolismo , Transplante Isogênico/fisiologia
5.
J Exp Med ; 192(10): 1453-66, 2000 Nov 20.
Artigo em Inglês | MEDLINE | ID: mdl-11085747

RESUMO

B cell maturation is a very selective process that requires finely tuned differentiation and survival signals. B cell activation factor from the TNF family (BAFF) is a TNF family member that binds to B cells and potentiates B cell receptor (BCR)-mediated proliferation. A role for BAFF in B cell survival was suggested by the observation of reduced peripheral B cell numbers in mice treated with reagents blocking BAFF, and high Bcl-2 levels detected in B cells from BAFF transgenic (Tg) mice. We tested in vitro the survival effect of BAFF on lymphocytes derived from primary and secondary lymphoid organs. BAFF induced survival of a subset of splenic immature B cells, referred to as transitional type 2 (T2) B cells. BAFF treatment allowed T2 B cells to survive and differentiate into mature B cells in response to signals through the BCR. The T2 and the marginal zone (MZ) B cell compartments were particularly enlarged in BAFF Tg mice. Immature transitional B cells are targets for negative selection, a feature thought to promote self-tolerance. These findings support a model in which excessive BAFF-mediated survival of peripheral immature B cells contributes to the emergence and maturation of autoreactive B cells, skewed towards the MZ compartment. This work provides new clues on mechanisms regulating B cell maturation and tolerance.


Assuntos
Autoimunidade , Subpopulações de Linfócitos B/imunologia , Células-Tronco Hematopoéticas/imunologia , Proteínas de Membrana/metabolismo , Fator de Necrose Tumoral alfa/metabolismo , Animais , Fator Ativador de Células B , Subpopulações de Linfócitos B/citologia , Diferenciação Celular , Sobrevivência Celular , Células Cultivadas , Células-Tronco Hematopoéticas/citologia , Camundongos , Modelos Imunológicos , Baço/citologia , Baço/imunologia
6.
J Exp Med ; 183(3): 867-78, 1996 Mar 01.
Artigo em Inglês | MEDLINE | ID: mdl-8642291

RESUMO

Surface lymphotoxin (LT) is a heteromeric complex of LT-alpha and LT-beta chains that binds to the LT-beta receptor (LT-beta-R), a member of the tumor necrosis factor (TNF) family of receptors. The biological function of this receptor-ligand system is poorly characterized. Since signaling through other members of this receptor family can induce cell death, e.g., the TNF and Fas receptors, it is important to determine if similar signaling events can be communicated via the LT-beta-R. A soluble form of the surface complex was produced by coexpression of LT-alpha and a converted form of LT-beta wherein the normally type II LT-beta membrane protein was changed to a type I secreted form. Recombinant LT-alpha 1/beta 2 was cytotoxic to the human adenocarcinoma cell lines HT-29, WiDr, MDA-MB-468, and HT-3 when added with the synergizing agent interferon (IFN) gamma. When immobilized on a plastic surface, anti-LT-beta-R monoclonal antibodies (mAbs) induced the death of these cells, demonstrating direct signaling via the LT-beta-R. Anti-LT-beta-R mAbs were also identified that inhibited ligand-induced cell death, whereas others were found to potentiate the activity of the ligand when added in solution. The human WiDr adenocarcinoma line forms solid tumors in immunocompromised mice, and treatment with an anti-LT-beta-R antibody combined with human IFN-gamma arrested tumor growth. The delineation of a biological signaling event mediated by the LT-beta-R opens a window for further studies on its immunological role, and furthermore, activation of the LT-beta-R may have an application in tumor therapy.


Assuntos
Apoptose , Interferon gama/farmacologia , Linfotoxina-alfa/fisiologia , Receptores do Fator de Necrose Tumoral/fisiologia , Transdução de Sinais , Adenocarcinoma/patologia , Animais , Anticorpos Monoclonais/farmacologia , Apoptose/efeitos dos fármacos , Morte Celular/efeitos dos fármacos , Linhagem Celular , Relação Dose-Resposta a Droga , Feminino , Citometria de Fluxo , Humanos , Cinética , Receptor beta de Linfotoxina , Linfotoxina-alfa/imunologia , Camundongos/imunologia , Receptores do Fator de Necrose Tumoral/efeitos dos fármacos , Proteínas Recombinantes/farmacologia , Células Tumorais Cultivadas
7.
J Exp Med ; 190(11): 1697-710, 1999 Dec 06.
Artigo em Inglês | MEDLINE | ID: mdl-10587360

RESUMO

The cause of many autoimmune and inflammatory diseases is unresolved, although dysregulated production of tumor necrosis factor (TNF) family members appears to be important in many cases. BAFF, a new member of the TNF family, binds to B cells and costimulates their growth in vitro. Mice transgenic for BAFF have vastly increased numbers of mature B and effector T cells, and develop autoimmune-like manifestations such as the presence of high levels of rheumatoid factors, circulating immune complexes, anti-DNA autoantibodies, and immunoglobulin deposition in the kidneys. This phenotype is reminiscent of certain human autoimmune disorders and suggests that dysregulation of BAFF expression may be a critical element in the chain of events leading to autoimmunity.


Assuntos
Autoanticorpos/sangue , Doenças Autoimunes/imunologia , Linfócitos B/imunologia , Doenças Linfáticas/imunologia , Proteínas de Membrana/genética , Proteínas de Membrana/imunologia , Fator de Necrose Tumoral alfa/genética , Fator de Necrose Tumoral alfa/imunologia , Animais , Anticorpos Antinucleares/sangue , Doenças Autoimunes/genética , Doenças Autoimunes/patologia , Fator Ativador de Células B , Citometria de Fluxo , Humanos , Imunoglobulina A/sangue , Imunoglobulina G/sangue , Imunoglobulina M/sangue , Imunoglobulinas/metabolismo , Rim/imunologia , Rim/patologia , Cinética , Contagem de Leucócitos , Pulmão/imunologia , Doenças Linfáticas/genética , Doenças Linfáticas/patologia , Camundongos , Camundongos Transgênicos , Reação em Cadeia da Polimerase Via Transcriptase Reversa , Fator Reumatoide/sangue , Linfócitos T/imunologia
8.
J Exp Med ; 193(11): 1227-38, 2001 Jun 04.
Artigo em Inglês | MEDLINE | ID: mdl-11390430

RESUMO

Lymph nodes (LNs) are important sentinal organs, populated by circulating lymphocytes and antigen-bearing cells exiting the tissue beds. Although cellular and humoral immune responses are induced in LNs by antigenic challenge, it is not known if LNs are essential for acquired immunity. We examined immune responses in mice that lack LNs due to genetic deletion of lymphotoxin ligands or in utero blockade of membrane lymphotoxin. We report that LNs are absolutely required for generating contact hypersensitivity, a T cell-dependent cellular immune response induced by epicutaneous hapten. We show that the homing of epidermal Langerhans cells in response to hapten application is specifically directed to LNs, providing a cellular basis for this unique LN function. In contrast, the spleen cannot mediate contact hypersensitivity because antigen-bearing epidermal Langerhans cells do not access splenic white pulp. Finally, we formally demonstrate that LNs provide a unique environment essential for generating this acquired immune response by reversing the LN defect in lymphotoxin-alpha(-/)- mice, thereby restoring the capacity for contact hypersensitivity.


Assuntos
Dermatite de Contato/etiologia , Linfonodos/fisiologia , Linfotoxina-alfa/fisiologia , Animais , Movimento Celular , Células Dendríticas/fisiologia , Feminino , Células de Langerhans/fisiologia , Linfotoxina-beta , Proteínas de Membrana/fisiologia , Camundongos , Camundongos Endogâmicos BALB C , Camundongos Endogâmicos C3H
9.
J Exp Med ; 192(11): 1677-84, 2000 Dec 04.
Artigo em Inglês | MEDLINE | ID: mdl-11104810

RESUMO

A proliferation-inducing ligand (APRIL) is a ligand of the tumor necrosis factor (TNF) family that stimulates tumor cell growth in vitro and in vivo. Expression of APRIL is highly upregulated in many tumors including colon and prostate carcinomas. Here we identify B cell maturation antigen (BCMA) and transmembrane activator and calcium modulator and cyclophilin ligand (CAML) interactor (TACI), two predicted members of the TNF receptor family, as receptors for APRIL. APRIL binds BCMA with higher affinity than TACI. A soluble form of BCMA, which inhibits the proliferative activity of APRIL in vitro, decreases tumor cell proliferation in nude mice. Growth of HT29 colon carcinoma cells is blocked when mice are treated once per week with the soluble receptor. These results suggest an important role for APRIL in tumorigenesis and point towards a novel anticancer strategy.


Assuntos
Proteínas Adaptadoras de Transdução de Sinal , Linfócitos B/fisiologia , Transformação Celular Neoplásica , Proteínas de Membrana/metabolismo , Receptores do Fator de Necrose Tumoral/metabolismo , Fator de Necrose Tumoral alfa/metabolismo , Células 3T3 , Animais , Fator Ativador de Células B , Antígeno de Maturação de Linfócitos B , Proteínas de Transporte/metabolismo , Divisão Celular , Linhagem Celular Transformada , Células HT29 , Humanos , Proteínas de Membrana/genética , Camundongos , Camundongos Nus , Neoplasias/terapia , Receptores do Fator de Necrose Tumoral/genética , Proteínas Recombinantes de Fusão/genética , Proteínas Recombinantes de Fusão/metabolismo , Solubilidade , Proteína Transmembrana Ativadora e Interagente do CAML , Células Tumorais Cultivadas , Membro 13 da Superfamília de Ligantes de Fatores de Necrose Tumoral , Fator de Necrose Tumoral alfa/genética
10.
J Exp Med ; 189(2): 403-12, 1999 Jan 18.
Artigo em Inglês | MEDLINE | ID: mdl-9892622

RESUMO

Mice deficient in the cytokines tumor necrosis factor (TNF) or lymphotoxin (LT) alpha/beta lack polarized B cell follicles in the spleen. Deficiency in CXC chemokine receptor 5 (CXCR5), a receptor for B lymphocyte chemoattractant (BLC), also causes loss of splenic follicles. Here we report that BLC expression by follicular stromal cells is defective in TNF-, TNF receptor 1 (TNFR1)-, LTalpha- and LTbeta-deficient mice. Treatment of adult mice with antagonists of LTalpha1beta2 also leads to decreased BLC expression. These findings indicate that LTalpha1beta2 and TNF have a role upstream of BLC/CXCR5 in the process of follicle formation. In addition to disrupted follicles, LT-deficient animals have disorganized T zones. Expression of the T cell attractant, secondary lymphoid tissue chemokine (SLC), by T zone stromal cells is found to be markedly depressed in LTalpha-, and LTbeta-deficient mice. Expression of the SLC-related chemokine, Epstein Barr virus-induced molecule 1 ligand chemokine (ELC), is also reduced. Exploring the basis for the reduced SLC expression led to identification of further disruptions in T zone stromal cells. Together these findings indicate that LTalpha1beta2 and TNF are required for the development and function of B and T zone stromal cells that make chemokines necessary for lymphocyte compartmentalization in the spleen.


Assuntos
Linfócitos B/metabolismo , Movimento Celular/imunologia , Proteínas de Ligação ao GTP/metabolismo , Linfotoxina-alfa/metabolismo , Receptores de Citocinas/metabolismo , Baço/imunologia , Linfócitos T/metabolismo , Fator de Necrose Tumoral alfa/metabolismo , Animais , Moléculas de Adesão Celular/metabolismo , Quimiocina CXCL13 , Quimiocinas CXC/genética , Regulação da Expressão Gênica/genética , Hibridização In Situ , Linfotoxina-alfa/antagonistas & inibidores , Camundongos , Camundongos Knockout , RNA Mensageiro/genética , Receptores CXCR5 , Receptores de Quimiocinas , Baço/citologia , Baço/metabolismo
11.
J Exp Med ; 189(11): 1747-56, 1999 Jun 07.
Artigo em Inglês | MEDLINE | ID: mdl-10359578

RESUMO

Members of the tumor necrosis factor (TNF) family induce pleiotropic biological responses, including cell growth, differentiation, and even death. Here we describe a novel member of the TNF family, designated BAFF (for B cell activating factor belonging to the TNF family), which is expressed by T cells and dendritic cells. Human BAFF was mapped to chromosome 13q32-34. Membrane-bound BAFF was processed and secreted through the action of a protease whose specificity matches that of the furin family of proprotein convertases. The expression of BAFF receptor appeared to be restricted to B cells. Both membrane-bound and soluble BAFF induced proliferation of anti-immunoglobulin M-stimulated peripheral blood B lymphocytes. Moreover, increased amounts of immunoglobulins were found in supernatants of germinal center-like B cells costimulated with BAFF. These results suggest that BAFF plays an important role as costimulator of B cell proliferation and function.


Assuntos
Linfócitos B/imunologia , Proteínas de Membrana/fisiologia , Receptores do Fator de Necrose Tumoral/fisiologia , Fator de Necrose Tumoral alfa/fisiologia , Sequência de Aminoácidos , Animais , Fator Ativador de Células B , Linfócitos B/citologia , Sequência de Bases , Divisão Celular , Linhagem Celular , Mapeamento Cromossômico , Cromossomos Humanos Par 13/genética , Clonagem Molecular , Primers do DNA/genética , Células Dendríticas/imunologia , Humanos , Ligantes , Ativação Linfocitária , Proteínas de Membrana/genética , Camundongos , Dados de Sequência Molecular , Receptores do Fator de Necrose Tumoral/genética , Homologia de Sequência de Aminoácidos , Linfócitos T/imunologia , Fator de Necrose Tumoral alfa/genética
12.
J Exp Med ; 192(1): 129-35, 2000 Jul 03.
Artigo em Inglês | MEDLINE | ID: mdl-10880534

RESUMO

The tumor necrosis factor (TNF) family member B cell activating factor (BAFF) binds B cells and enhances B cell receptor-triggered proliferation. We find that B cell maturation antigen (BCMA), a predicted member of the TNF receptor family expressed primarily in mature B cells, is a receptor for BAFF. Although BCMA was previously localized to the Golgi apparatus, BCMA was found to be expressed on the surface of transfected cells and tonsillar B cells. A soluble form of BCMA, which inhibited the binding of BAFF to a B cell line, induced a dramatic decrease in the number of peripheral B cells when administered in vivo. Moreover, culturing splenic cells in the presence of BAFF increased survival of a percentage of the B cells. These results are consistent with a role for BAFF in maintaining homeostasis of the B cell population.


Assuntos
Linfócitos B/imunologia , Ativação Linfocitária , Proteínas de Membrana/imunologia , Proteínas de Membrana/fisiologia , Receptores do Fator de Necrose Tumoral/imunologia , Receptores do Fator de Necrose Tumoral/fisiologia , Fator de Necrose Tumoral alfa , Animais , Fator Ativador de Células B , Antígeno de Maturação de Linfócitos B , Linhagem Celular , Sobrevivência Celular , Homeostase , Humanos , Imunoglobulina G/imunologia , Cadeias kappa de Imunoglobulina/genética , Cadeias kappa de Imunoglobulina/imunologia , Proteínas de Membrana/genética , Camundongos , Camundongos Endogâmicos BALB C , Tonsila Palatina/imunologia , Receptores do Fator de Necrose Tumoral/genética , Proteínas Recombinantes/imunologia , Baço/imunologia , Transfecção
13.
Science ; 254(5034): 1007-10, 1991 Nov 15.
Artigo em Inglês | MEDLINE | ID: mdl-1948070

RESUMO

Phospholipase A2 (PLA2) participates in a wide range of cellular processes including inflammation and transmembrane signaling. A human nonpancreatic secretory PLA2 (hnps-PLA2) has been identified that is found in high concentrations in the synovial fluid of patients with rheumatoid arthritis and in the plasma of patients with septic shock. This enzyme is secreted from certain cell types in response to the proinflammatory cytokines, tumor necrosis factor or interleukin-1. The crystal structures of the calcium-bound form of this enzyme have been determined at physiological pH both in the presence [2.1 angstrom (A) resolution] and absence (2.2 A resolution) of a transition-state analogue. Although the critical features that suggest the chemistry of catalysis are identical to those inferred from the crystal structures of other extracellular PLA2s, the shape of the hydrophobic channel of hnps-PLA2 is uniquely modulated by substrate binding.


Assuntos
Inflamação/enzimologia , Fosfolipases A/ultraestrutura , Sequência de Aminoácidos , Sítios de Ligação , Cálcio/química , Gráficos por Computador , Cristalografia , Espaço Extracelular/enzimologia , Humanos , Dados de Sequência Molecular , Fosfolipases A/antagonistas & inibidores , Fosfolipases A2 , Conformação Proteica , Proteínas Recombinantes , Alinhamento de Sequência , Difração de Raios X
14.
Science ; 264(5159): 707-10, 1994 Apr 29.
Artigo em Inglês | MEDLINE | ID: mdl-8171323

RESUMO

Tumor necrosis factor (TNF) and lymphotoxin-alpha (LT-alpha) are members of a family of secreted and cell surface cytokines that participate in the regulation of immune and inflammatory responses. The cell surface form of LT-alpha is assembled during biosynthesis as a heteromeric complex with lymphotoxin-beta (LT-beta), a type II transmembrane protein that is another member of the TNF ligand family. Secreted LT-alpha is a homotrimer that binds to distinct TNF receptors of 60 and 80 kilodaltons; however, these receptors do not recognize the major cell surface LT-alpha-LT-beta complex. A receptor specific for human LT-beta was identified, which suggests that cell surface LT may have functions that are distinct from those of secreted LT-alpha.


Assuntos
Linfotoxina-alfa/metabolismo , Receptores do Fator de Necrose Tumoral/metabolismo , Fator de Necrose Tumoral alfa/metabolismo , Sequência de Aminoácidos , Sequência de Bases , Sítios de Ligação , Cisteína/química , Humanos , Hibridomas , Ligantes , Receptor beta de Linfotoxina , Dados de Sequência Molecular , Receptores do Fator de Necrose Tumoral/química , Proteínas Recombinantes de Fusão/metabolismo , Linfócitos T/imunologia , Acetato de Tetradecanoilforbol/farmacologia
15.
Science ; 293(5537): 2108-11, 2001 Sep 14.
Artigo em Inglês | MEDLINE | ID: mdl-11509692

RESUMO

B cell homeostasis has been shown to critically depend on BAFF, the B cell activation factor from the tumor necrosis factor (TNF) family. Although BAFF is already known to bind two receptors, BCMA and TACI, we have identified a third receptor for BAFF that we have termed BAFF-R. BAFF-R binding appears to be highly specific for BAFF, suggesting a unique role for this ligand-receptor interaction. Consistent with this, the BAFF-R locus is disrupted in A/WySnJ mice, which display a B cell phenotype qualitatively similar to that of the BAFF-deficient mice. Thus, BAFF-R appears to be the principal receptor for BAFF-mediated mature B cell survival.


Assuntos
Linfócitos B/fisiologia , Proteínas de Membrana/metabolismo , Receptores do Fator de Necrose Tumoral/metabolismo , Fator de Necrose Tumoral alfa/metabolismo , Sequência de Aminoácidos , Animais , Fator Ativador de Células B , Receptor do Fator Ativador de Células B , Antígeno de Maturação de Linfócitos B , Linfócitos B/imunologia , Linfócitos B/metabolismo , Linhagem Celular , Mapeamento Cromossômico , Cromossomos Humanos Par 22 , Clonagem Molecular , Homeostase , Humanos , Ligantes , Tecido Linfoide/metabolismo , Masculino , Camundongos , Camundongos Endogâmicos A , Camundongos Endogâmicos C57BL , Dados de Sequência Molecular , RNA Mensageiro/química , RNA Mensageiro/genética , RNA Mensageiro/metabolismo , Receptores do Fator de Necrose Tumoral/química , Receptores do Fator de Necrose Tumoral/genética , Proteínas Recombinantes de Fusão/metabolismo , Transdução de Sinais , Transfecção , Proteína Transmembrana Ativadora e Interagente do CAML
16.
Biochim Biophys Acta ; 448(2): 338-51, 1976 Oct 05.
Artigo em Inglês | MEDLINE | ID: mdl-9158

RESUMO

The characteristics of Ca2+ transport across the excitable membrane of Paramecium aurelia were studied by measuring 45Ca2+ influx and efflux. The intracellular concentration of free Ca2+ in resting P. aurelia was at least ten times less than the extracellular concentration. Ca2+ influx was easily measurable at 0 degrees C, but not at 23 degrees C. The influx of 45Ca2+ was stimulated by the same conditions which cause membrane depolarization and ciliary reversal. Addition of Na+ and K+ (which stimulate ciliary reversal) resulted in a 10-fold increase in the rate of Ca2+ influx. An externally applied, pulsed, electric field (1-2 mA/cm2 of electrode surface), caused the rate of Ca2+ influx to increase 3-5 times, with the extent of stimulation dependent on the current density and the pulse width. Ca2+ influx had the characteristics of a passive transport system and was associated with the chemically or electrically triggered Ca2+ "gating" mechanism, which has been studied electrophysiologically. In contrast, Ca2+ efflux appeared to be catalyzed by an active transport system. With cells previously loaded at 0 degrees C with 45Ca2+, Ca2+ efflux was rapid at 23 degrees C, but did not occur at 0 degrees C. This active Ca2+ efflux mechanism is probably responsible for maintaining the low internal Ca2+ levels in unstimulated cells.


Assuntos
Cálcio/metabolismo , Membrana Celular/metabolismo , Paramecium/metabolismo , Azidas/farmacologia , Transporte Biológico , Cátions Bivalentes/farmacologia , Cátions Monovalentes/farmacologia , Cianetos/farmacologia , Estimulação Elétrica , Concentração de Íons de Hidrogênio , Inulina/metabolismo , Potássio/farmacologia , Sódio/farmacologia , Temperatura
17.
Biochim Biophys Acta ; 684(2): 172-8, 1982 Jan 22.
Artigo em Inglês | MEDLINE | ID: mdl-7055560

RESUMO

The effects of the local anesthetic dibucaine on the membrane headgroup conformations of phosphatidylcholine and phosphatidylethanolamine were determined using 2H- and 31P-NMR. The size of the deuterium quadrupole splittings of the two methylene segments of the choline and ethanolamine groups changed dramatically and the 31-phosphorus chemical shift anisotropy of the phosphatidylcholine headgroup decreased by about 7 ppm in the presence of local anesthetic. The quadrupole splittings of the 3-glycerol and choline methyl segments were relatively insensitive to the addition of dibucaine. The headgroup data for dibucaine addition paralleled similar data for the addition of various cations. These NMR results agree with the previous observation that these drugs displace calcium from phospholipids. The effects of this local anesthetic on these headgroups were distinctly different from the changes induced by cholesterol, heat and the general anesthetic chloroform.


Assuntos
Dibucaína , Fosfatidilcolinas , Fosfatidiletanolaminas , Cátions Bivalentes , Espectroscopia de Ressonância Magnética , Modelos Biológicos , Conformação Molecular , Relação Estrutura-Atividade
18.
Cell Death Differ ; 9(12): 1321-33, 2002 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-12478469

RESUMO

The HT29 adenocarcinoma is a common model of epithelial cell differentiation and colorectal cancer and its death is an oft-analyzed response to TNF family receptor signaling. The death event itself remains poorly characterized and here we have examined the involvement of caspases using pan-caspase inhibitors. zVAD-fmk did not block death of HT29 cells in response to activation of the Fas, TRAIL, TNF, TWEAK and LTbeta receptors. The secondary induction of TNF or the other known bona fide death inducing ligands did not account for death following LTbeta receptor activation indicating that TNF family receptors can trigger a caspase-independent death pathway regardless of the presence of canonical death domains in the receptor. To provide a frame of reference, the phenotype of HT29 death was compared to four other TNF family receptor triggered death events; Fas induced Jurkat cell apoptosis, TNF/zVAD induced L929 fibroblast necrosis, TNF induced death of WEHI 164 fibroblastoid cells and TNF/zVAD induced U937 death. The death of HT29 and U937 cells under these conditions is an intermediate form with both necrotic and apoptotic features. The efficient coupling of TNF receptors to a caspase-independent death event in an epithelial cell suggests an alternative approach to cancer therapy.


Assuntos
Adenocarcinoma/enzimologia , Caspases/metabolismo , Neoplasias Colorretais/enzimologia , Células Epiteliais/enzimologia , Receptores do Fator de Necrose Tumoral/metabolismo , Transporte Ativo do Núcleo Celular/efeitos dos fármacos , Transporte Ativo do Núcleo Celular/genética , Adenocarcinoma/tratamento farmacológico , Adenocarcinoma/genética , Clorometilcetonas de Aminoácidos/farmacologia , Animais , Apoptose/efeitos dos fármacos , Apoptose/genética , Inibidores de Caspase , Neoplasias Colorretais/tratamento farmacológico , Neoplasias Colorretais/genética , Inibidores Enzimáticos/farmacologia , Células Epiteliais/efeitos dos fármacos , Células Epiteliais/ultraestrutura , Humanos , Receptor beta de Linfotoxina , Camundongos , Microscopia Eletrônica , Mitocôndrias/efeitos dos fármacos , Mitocôndrias/enzimologia , Receptores do Ligante Indutor de Apoptose Relacionado a TNF , Receptores do Fator de Necrose Tumoral/efeitos dos fármacos , Receptor de TWEAK , Células Tumorais Cultivadas/efeitos dos fármacos , Células Tumorais Cultivadas/enzimologia , Células Tumorais Cultivadas/ultraestrutura , Receptor fas/efeitos dos fármacos , Receptor fas/metabolismo
19.
Cell Death Differ ; 5(6): 497-505, 1998 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-10200501

RESUMO

The lymphotoxin beta receptor (LTbetaR), and its ligand, LTalpha1beta2, have been proposed to play a key role in the development and organization of lymphoid tissues. The LTbetaR is expressed on a variety of human primary and transformed cells, but strikingly absent on T or B lymphocytes and primary monocytes or peripheral dendritic cells, although LTbetaR is detected on some myeloid leukemic lines. In the developing thymus LTbetaR is prominent along the trabeculae and into the medulla upto corticomedullary junction. In the spleen, LTbetaR is prominently expressed by cells in the red pulp and along the borders of red and white pulp which colocalizes with reticular stromal cells. The LTbetaR is expressed on a human follicular dendritic cell line, FDC-1, and signals expression of CD54 when ligated with the LTalpha1beta2 complex. These results support the concept that directional interactions between LTalpha1beta2 bearing lymphocytes and LTbetaR bearing stromal cells are involved in the organization of lymphoid tissue.


Assuntos
Tecido Linfoide/metabolismo , Linfotoxina-alfa/metabolismo , Proteínas de Membrana/metabolismo , Receptores do Fator de Necrose Tumoral/metabolismo , Linhagem Celular , Células Dendríticas/metabolismo , Citometria de Fluxo , Humanos , Molécula 1 de Adesão Intercelular/metabolismo , Receptor beta de Linfotoxina , Linfotoxina-beta , Monócitos/metabolismo , Ligação Proteica , Baço/metabolismo , Timo/metabolismo
20.
FEBS Lett ; 261(2): 247-52, 1990 Feb 26.
Artigo em Inglês | MEDLINE | ID: mdl-1690147

RESUMO

We have developed two monoclonal antibodies to human lipocortin-1 (103 and 105) as reagents for quantitating the protein in biological systems and neutralizing its activity. Lipo 105 is a high affinity antibody that is functional in ELISA and Western blot formats. The antibody recognizes a site between amino acids 30 and 55 in the lipocortin-1 sequence and can be used on native or denatured protein. Lipo 103 is an antibody that neutralizes the phospholipase A2 inhibitory activity of lipocortin-1 by blocking binding of the protein to phospholipid surfaces. The antibody is specific for native human lipocortin-1. Lipo 103 was recently shown to block lipocortin-1-dependent differentiation of a squamous carcinoma cell line, demonstrating its usefulness as a probe for function.


Assuntos
Anticorpos Monoclonais/imunologia , Proteínas de Ligação ao Cálcio/imunologia , Animais , Anexinas , Anticorpos Monoclonais/biossíntese , Especificidade de Anticorpos , Western Blotting , Proteínas de Ligação ao Cálcio/farmacologia , Brometo de Cianogênio , Ensaio de Imunoadsorção Enzimática , Epitopos/imunologia , Feminino , Humanos , Indicadores e Reagentes , Camundongos , Camundongos Endogâmicos BALB C , Fragmentos de Peptídeos/imunologia , Mapeamento de Peptídeos , Fosfolipases A/antagonistas & inibidores , Fosfolipases A2 , Proteínas Recombinantes
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