RESUMEN
Epithelial tissues continually undergo apoptosis. Commensal organisms that inhabit the epithelium influence tissue homeostasis, in which regulatory T cells (Treg cells) have a central role. However, the physiological importance of epithelial cell apoptosis and how the number of Treg cells is regulated are both incompletely understood. Here we found that apoptotic epithelial cells negatively regulated the commensal-stimulated proliferation of Treg cells. Gut commensals stimulated CX3CR1(+)CD103(-)CD11b(+) dendritic cells (DCs) to produce interferon-ß (IFN-ß), which augmented the proliferation of Treg cells in the intestine. Conversely, phosphatidylserine exposed on apoptotic epithelial cells suppressed IFN-ß production by the DCs via inhibitory signaling mediated by the cell-surface glycoprotein CD300a and thus suppressed Treg cell proliferation. Our findings reveal a regulatory role for apoptotic epithelial cells in maintaining the number of Treg cell and tissue homeostasis.
Asunto(s)
Apoptosis/inmunología , Epidermis/inmunología , Células Epiteliales/inmunología , Microbioma Gastrointestinal/inmunología , Interferón beta/inmunología , Mucosa Intestinal/inmunología , Mucosa Respiratoria/inmunología , Linfocitos T Reguladores/inmunología , Alérgenos/toxicidad , Animales , Colitis/inducido químicamente , Colitis/inmunología , Colitis/patología , Colon/citología , Colon/inmunología , Células Dendríticas/inmunología , Dermatitis Alérgica por Contacto/etiología , Dermatitis Alérgica por Contacto/inmunología , Dermatitis Alérgica por Contacto/patología , Sulfato de Dextran/toxicidad , Células Epidérmicas , Citometría de Flujo , Inmunohistoquímica , Mucosa Intestinal/citología , Células de Langerhans/inmunología , Pulmón/citología , Pulmón/inmunología , Ratones , Ratones Noqueados , Ovalbúmina/toxicidad , Reacción en Cadena en Tiempo Real de la Polimerasa , Receptores Inmunológicos/genética , Mucosa Respiratoria/citología , Infecciones por Salmonella/inmunología , Salmonella typhimuriumRESUMEN
Sex hormones are essential for neural circuit development and sex-specific behaviors. Male behaviors require both testosterone and estrogen, but it is unclear how the two hormonal pathways intersect. Circulating testosterone activates the androgen receptor (AR) and is also converted into estrogen in the brain via aromatase. We demonstrate extensive sexual dimorphism in the number and projections of aromatase-expressing neurons. The masculinization of these cells is independent of AR but can be induced in females by either testosterone or estrogen, indicating a role for aromatase in sexual differentiation of these neurons. We provide evidence suggesting that aromatase is also important in activating male-specific aggression and urine marking because these behaviors can be elicited by testosterone in males mutant for AR and in females subjected to neonatal estrogen exposure. Our results suggest that aromatization of testosterone into estrogen is important for the development and activation of neural circuits that control male territorial behaviors.
Asunto(s)
Encéfalo/metabolismo , Estrógenos/metabolismo , Vías Nerviosas , Caracteres Sexuales , Animales , Animales Recién Nacidos , Aromatasa/metabolismo , Supervivencia Celular , Estrógenos/biosíntesis , Femenino , Masculino , Ratones , Neuronas/metabolismo , Receptores Androgénicos/metabolismo , Conducta Sexual Animal , TerritorialidadRESUMEN
Adult T-cell leukemia/lymphoma (ATL) is a hematopoietic malignancy with a poor prognosis that develops in approximately 5% of human T-cell leukemia virus type 1 (HTLV-1) carriers. Cyclin-dependent kinase 9 (CDK9), together with Cyclin T, forms a transcription elongation factor, positive transcription elongation factor b (P-TEFb). P-TEFb promotes transcriptional elongation by phosphorylating the second serine (Ser2) of the seven amino acid repeat sequence in the C-terminal domain of RNA polymerase II (RNAP II). CDK9 inhibitors suppress cell proliferation by inducing apoptosis in chronic lymphocytic leukemia and breast cancer but there are no reports on autophagy of CDK9 inhibitors. Here, we investigated the effect of LY2857785, a novel CDK9 selective inhibitor, on cell death in ATL-related cell lines in vitro, freshly isolated cells from ATL patients ex vivo, and on ATL tumor xenografts in NOD/SCID mice in vivo. LY2857785 significantly reduced cell viability and induced apoptosis, as shown by annexin V-positive cells, cleaved poly(ADP-ribose) polymerase (PARP), and cleaved caspase-3, and suppressed the levels of anti-apoptotic protein myeloid cell leukemia-1 (MCL-1). LY2857785 decreased RNAP II Ser2 phosphorylation and downstream c-Myc protein levels. Interestingly, LY2857785 also increased microtubule-associated proteins 1A/1B light chain 3B (LC3)-II binding to autophagosome membranes. Furthermore, LY2857785 decreased the viability of freshly isolated ATL cells and induced apoptosis. Finally, LY2857785 significantly decreased the growth of ATL tumor xenografts. These results suggest that LY2857785 induces cell death of ATL cells by MCL-1-dependent apoptosis and autophagy and has anti-tumor activity.
Asunto(s)
Neoplasias de la Mama , Leucemia-Linfoma de Células T del Adulto , Linfoma , Ratones , Adulto , Animales , Humanos , Femenino , Ratones Endogámicos NOD , Ratones SCID , Leucemia-Linfoma de Células T del Adulto/tratamiento farmacológico , Factor B de Elongación Transcripcional Positiva , Proteína 1 de la Secuencia de Leucemia de Células Mieloides , Inhibidores de Proteínas Quinasas , Apoptosis , Autofagia , Quinasa 9 Dependiente de la CiclinaRESUMEN
Germinal centers (GCs) in secondary lymphoid organs generate large numbers of apoptotic B cells that must be eliminated by phagocytes to prevent the development of autoimmune diseases. Although tingible body macrophages engulf apoptotic GC B cells, whether stromal cells are also involved in this process is unclear. In this study, we identified marginal reticular cells (MRCs) as novel nonprofessional phagocytes for the clearance of apoptotic GC B cells in the spleen. We used CD19eGFP (CD19creZ/EG) mice, which express enhanced GFP (eGFP) under the control of CD19cre expression, to track B cells in the GCs after immunization with NP-chicken γ globulin plus aluminum salt. We demonstrated that the MRC population, as determined by expression of podoplanin or Rankl, specifically showed an eGFP signal in the cytoplasm after immunization. These results suggest that MRCs contribute to the clearance of apoptotic B cells in GCs.
Asunto(s)
Apoptosis/inmunología , Linfocitos B/inmunología , Centro Germinal/inmunología , Fagocitos/inmunología , Animales , Enfermedades Autoinmunes/inmunología , Citoplasma/inmunología , Proteínas Fluorescentes Verdes/inmunología , Macrófagos/inmunología , Ratones , Ratones Endogámicos C57BL , Bazo/inmunología , Células del Estroma/inmunologíaRESUMEN
Although both Fcα/µ receptor (Fcα/µR) and polymeric Ig receptor (poly-IgR) are Fc receptors for IgA and IgM and are functionally and genetically related, the expression profile of Fcα/µR is unique. Unlike poly-IgR, Fcα/µR is expressed on marginal zone (MZ) B cells and follicular dendritic cells, suggesting that Fcα/µR plays an important role in humoral immune responses. Fcα/µR mediates endocytosis of the IgM immune complex (IC). Recent research demonstrated that Fcα/µR downregulated retention of the IgM IC with a T-independent (TI) antigen on MZ B cells and follicular dendritic cells due to endocytosis of the IgM IC, suppressing germinal center formation, affinity maturation, and memory B-cell generation in response to TI antigen challenge. In addition, Fcα/µR physically associates with Toll-like receptor 4 (TLR4) and augments TLR4 oligomerization and signaling in MZ B cells upon lipopolysaccharide (LPS) challenge, leading to increased proinflammatory cytokine production by MZ B cells. Thus, Fcα/µR is a unique Fc receptor that is involved in humoral immune responses and inflammation.
Asunto(s)
Linfocitos B/inmunología , Linfocitos B/metabolismo , Células Dendríticas Foliculares/inmunología , Células Dendríticas Foliculares/metabolismo , Centro Germinal/inmunología , Centro Germinal/metabolismo , Inmunomodulación , Receptores Fc/metabolismo , Animales , Complejo Antígeno-Anticuerpo/metabolismo , Endocitosis , Epítopos de Linfocito T/inmunología , Expresión Génica , Humanos , Inmunidad Humoral , Inmunoglobulina A/inmunología , Inmunoglobulina A/metabolismo , Fragmentos Fc de Inmunoglobulinas/inmunología , Fragmentos Fc de Inmunoglobulinas/metabolismo , Inmunoglobulina M/inmunología , Inmunoglobulina M/metabolismo , Inflamación/genética , Inflamación/inmunología , Inflamación/metabolismo , Familia de Multigenes , Unión Proteica , Dominios y Motivos de Interacción de Proteínas , Receptores Fc/química , Receptores Fc/genéticaRESUMEN
Fc receptors play important roles for a wide array of immune responses. In contrast to the well-defined Fcγ and Fcε receptors, the molecular and functional characteristics of Fc receptors for IgA and IgM have remained incompletely understood for years. Recent progress has unveiled the characteristics of Fc receptors for IgA and IgM, including Fcα/µ receptor (Fcα/µR) (CD351), polymeric immunoglobulin receptor (poly-IgR), Fcα receptor (FcαRI) (CD89) and Fcµ receptor (FcµR). In this review, we summarize the molecular and functional characteristics of Fcα/µR in comparison with poly-IgR, FcµR and FcαRI, and focus particularly on the pro-inflammatory function of Fcα/µR expressed on marginal zone B cells in sepsis.
Asunto(s)
Linfocitos B/inmunología , Inflamación/inmunología , Receptores Fc/inmunología , Receptores Opioides mu/inmunología , Sepsis/inmunología , Animales , HumanosRESUMEN
BACKGROUND: Sirtuin 2 (SIRT2) is a member of the sirtuin family, nicotinamide adenine dinucleotide+-dependent deacylases, which participates in modulation of cell cycle control, neurodegeneration, and tumorigenesis. SIRT2 expression increases in acute myeloid leukemia blasts. Downregulation of SIRT2 using siRNA causes apoptosis of HeLa cells. Therefore, selective inhibitors of SIRT2 are candidate therapeutic agents for cancer. Adult T-cell leukemia/lymphoma (ATL) is a T-cell malignancy that has a poor prognosis and develops after long-term infection with human T-cell leukemia virus (HTLV)-1. Sirtuin 1 inhibition has been shown to induce apoptosis and autophagy in HTLV-1-infected cell lines, whereas the effects of SIRT2 inhibition alone have not been elucidated. METHODS: We assessed the efficacy of our small molecule selective SIRT2 inhibitors NCO-90/141 to induce leukemic cell death. Cell viability was examined using the cell proliferation reagent Cell Count Reagent SF. Apoptotic cells were detected by annexin V-FITC and terminal deoxynucleotidyl transferase dUTP nick end labeling assays by flow cytometry. Caspase activity was detected using an APOPCYTO Intracellular Caspase Activity Detection Kit. The presence of autophagic vacuoles was assessed using a Cyto-ID Autophagy Detection Kit. RESULTS: Our novel small molecule SIRT2-specific inhibitors NCO-90/141 inhibited cell growth of leukemic cell lines including HTLV-1-transformed T-cells. NCO-90/141 induced apoptosis via caspase activation and mitochondrial superoxide generation in leukemic cell lines. However, a caspase inhibitor did not prevent this caspase-associated cell death. Interestingly, NCO-90/141 increased the LC3-II level together with autophagosome accumulation, indicating autophagic cell death. Thus, NCO-90/141 simultaneously caused apoptosis and autophagy. CONCLUSIONS: These results suggest that NCO-90/141 are highly effective against leukemic cells in caspase-dependent or -independent manners via autophagy, and they may have a novel therapeutic potential for treatment of leukemias including ATL.
Asunto(s)
Antineoplásicos/farmacología , Apoptosis/efectos de los fármacos , Autofagia/efectos de los fármacos , Inhibidores de Histona Desacetilasas/farmacología , Leucemia/tratamiento farmacológico , Sirtuina 2/antagonistas & inhibidores , Caspasas/metabolismo , Proliferación Celular/efectos de los fármacos , Células HL-60 , Humanos , Células Jurkat , Leucemia/enzimología , Leucemia/patología , Proteínas Asociadas a Microtúbulos/metabolismo , Mitocondrias/efectos de los fármacos , Mitocondrias/enzimología , Mitocondrias/patología , Transducción de Señal/efectos de los fármacos , Sirtuina 2/metabolismo , Superóxidos/metabolismoRESUMEN
Although Th1 and Th2 cells are known to be involved in allergic inflammatory diseases, the molecular mechanisms underlying their differentiation are incompletely understood. In this study, we identified CD155 as a costimulatory molecule on CD4(+) T cells. Importantly, CD155-mediated signaling induced Th1 development in both humans and mice, as evidenced by production of IFN-γ and upregulation of Tbx21 transcription; these effects were independent of IL-12 but dependent on NF-κB-induced autocrine IFN-γ that triggered positive feedback via STAT1 activation. Mice genetically deficient in CD155 or treated with anti-CD155 Ab exhibited attenuated Th1-type contact hypersensitivity. Thus, CD155 plays an important regulatory role in helper T cell differentiation and allergic diseases.
Asunto(s)
Linfocitos T CD4-Positivos/inmunología , Linfocitos T CD4-Positivos/metabolismo , Hipersensibilidad/inmunología , Hipersensibilidad/metabolismo , Receptores Virales/metabolismo , Transducción de Señal , Animales , Anticuerpos Monoclonales/administración & dosificación , Anticuerpos Monoclonales/farmacología , Dermatitis por Contacto/tratamiento farmacológico , Dermatitis por Contacto/inmunología , Dermatitis por Contacto/metabolismo , Modelos Animales de Enfermedad , Humanos , Hipersensibilidad/tratamiento farmacológico , Interferón gamma/metabolismo , Interleucina-12/metabolismo , Ratones , Ratones Noqueados , Fosforilación , Receptores Virales/antagonistas & inhibidores , Receptores Virales/genética , Células TH1/inmunología , Células TH1/metabolismoRESUMEN
Microglia play an important role in receptor-mediated phagocytosis in the CNS. In brain abscess and other CNS infections, invading bacteria undergo opsonization with Igs or complement. Microglia recognize these opsonized pathogens by Fc or complement receptors triggering phagocytosis. In this study, we investigated the role of Fcα/µR, the less-studied receptor for IgM and IgA, in microglial phagocytosis. We showed that primary microglia, as well as N9 microglial cells, express Fcα/µR. We also showed that anti-Staphylococcus aureus IgM markedly increased the rate of microglial S. aureus phagocytosis. To unequivocally test the role of Fcα/µR in IgM-mediated phagocytosis, we performed experiments in microglia from Fcα/µR(-/-) mice. Surprisingly, we found that IgM-dependent phagocytosis of S. aureus was similar in microglia derived from wild-type or Fcα/µR(-/-) mice. We hypothesized that IgM-dependent activation of complement receptors might contribute to the IgM-mediated increase in phagocytosis. To test this, we used immunologic and genetic inactivation of complement receptor 3 components (CD11b and CD18) as well as C3. IgM-, but not IgG-mediated phagocytosis of S. aureus was reduced in wild-type microglia and macrophages following preincubation with an anti-CD11b blocking Ab. IgM-dependent phagocytosis of S. aureus was also reduced in microglia derived from CD18(-/-) and C3(-/-) mice. Taken together, our findings implicate complement receptor 3 and C3, but not Fcα/µR, in IgM-mediated phagocytosis of S. aureus by microglia.
Asunto(s)
Complemento C3/inmunología , Inmunoglobulina M/inmunología , Antígeno de Macrófago-1/inmunología , Microglía/inmunología , Fagocitosis/inmunología , Animales , Anticuerpos Bloqueadores/farmacología , Antígeno CD11b/inmunología , Antígenos CD18/genética , Antígenos CD18/inmunología , Línea Celular , Complemento C3/genética , Ratones , Ratones Endogámicos C57BL , Ratones Noqueados , Receptores Fc/biosíntesis , Receptores Fc/genética , Receptores Fc/inmunología , Infecciones Estafilocócicas/inmunología , Infecciones Estafilocócicas/microbiología , Staphylococcus aureus/inmunologíaRESUMEN
Sirtuins are nicotinamide adenine dinucleotide+-dependent deacetylases of which there are seven isoforms (SIRT1-7). Sirtuin activity is linked to gene expression, lifespan extension, neurodegeneration, and age-related disorders. Numerous studies have suggested that sirtuins could be of great significance with regard to both antiaging and tumorigenesis, depending on its targets in specific signaling pathways or in specific cancers. Recent studies have identified small chemical compounds that modulate sirtuins, and these modulators have enabled a greater understanding of the biological function and molecular mechanisms of sirtuins. This review highlights the possibility of sirtuins, especially SIRT1 and SIRT2, for cancer therapy targets, and focuses on the therapeutic potential of sirtuin modulators both in cancer prevention and treatment.
Asunto(s)
Antineoplásicos/farmacología , Sirtuinas/antagonistas & inhibidores , Animales , Antineoplásicos/química , Muerte Celular/efectos de los fármacos , Muerte Celular/genética , Activadores de Enzimas/química , Activadores de Enzimas/farmacología , Inhibidores de Histona Desacetilasas/química , Inhibidores de Histona Desacetilasas/farmacología , Inhibidores de Histona Desacetilasas/uso terapéutico , Humanos , Isoenzimas , Neoplasias/genética , Neoplasias/metabolismo , Sirtuinas/química , Sirtuinas/metabolismoRESUMEN
Acute graft-versus-host disease (GVHD) is a life-threatening complication following bone marrow transplantation; however, no effective molecular-targeting therapy has been determined. Here, we show that mice that received allogeneic splenocytes deficient in DNAX accessory molecule-1 (DNAM-1) had significantly milder GVHD and lower mortality than those that received allogeneic WT splenocytes. Donor CD8(+) T cells deficient in DNAM-1 showed significantly less proliferation and infiltration of the liver and intestines of recipient mice and produced less IFN-γ after coculture with allogeneic splenocytes than WT CD8(+) T cells. Mice prophylactically treated with an anti-DNAM-1 antibody showed milder GVHD and lower mortality than those treated with a control antibody. Moreover, treatment with a single administration of the antibody after the overt onset of GVHD ameliorated GVHD and prolonged survival. Finally, we show that the anti-DNAM-1 antibody therapy also ameliorated the overt GVHD in lethally irradiated mice after MHC-matched, minor antigen-mismatched bone marrow transplantation. These results indicate that DNAM-1 plays an important role in the development of GVHD and is an ideal molecular target for therapeutic approaches to GVHD.
Asunto(s)
Antígenos de Diferenciación de Linfocitos T/inmunología , Enfermedad Injerto contra Huésped/etiología , Enfermedad Injerto contra Huésped/inmunología , Enfermedad Aguda , Animales , Anticuerpos Monoclonales/uso terapéutico , Antígenos de Diferenciación de Linfocitos T/genética , Trasplante de Médula Ósea/efectos adversos , Trasplante de Médula Ósea/inmunología , Trasplante de Médula Ósea/patología , Linfocitos T CD4-Positivos/inmunología , Linfocitos T CD8-positivos/inmunología , Linfocitos T CD8-positivos/patología , Proliferación Celular , Femenino , Enfermedad Injerto contra Huésped/patología , Enfermedad Injerto contra Huésped/terapia , Interferón gamma/biosíntesis , Ligandos , Masculino , Ratones , Ratones Endogámicos BALB C , Ratones Endogámicos C3H , Ratones Endogámicos C57BL , Ratones Noqueados , Trasplante HomólogoRESUMEN
Adult T-cell leukemia/lymphoma (ATL) is an aggressive T cell leukemia/lymphoma caused by human T-cell lymphotropic virus type I (HTLV-1). Acadesine or 5-aminoimidazole-4-carboxamide riboside (AICAR) is an AMP-activated protein kinase (AMPK) activator that was recently shown to have tumor suppressive effects on B cell chronic lymphocytic leukemia, but not ATL. This study evaluated the cytotoxic effects of AICAR on ATL-related cell lines and its anti-tumor activity. Here, we demonstrated that AICAR induced cell death via apoptosis and the mitochondrial membrane depolarization of ATL-related cell lines (S1T, MT-1, and MT-2) but not non-HTLV-1-infected Jurkat cells. However, AICAR did not increase the phosphorylation levels of AMPKα. In addition, AICAR increased the expression of the death receptors (DR) DR4 and DR5, and necroptosis-related proteins including phosphorylated receptor-interacting protein family members and the mixed lineage kinase domain-like protein. Interestingly, HTLV-1 Tax, an HTLV-1-encoded oncogenic factor, did not affect AICAR-induced apoptosis. Furthermore, AICAR inhibited the growth of human ATL tumor xenografts in NOD/SCID/gamma mice in vivo. Together, these results suggest that AICAR induces AMPK-independent cell death in ATL-related cell lines and has anti-tumor activity, indicating that it might be a therapeutic agent for ATL.
Asunto(s)
Virus Linfotrópico T Tipo 1 Humano , Leucemia-Linfoma de Células T del Adulto , Ratones , Adulto , Animales , Humanos , Proteínas Quinasas Activadas por AMP/metabolismo , Leucemia-Linfoma de Células T del Adulto/tratamiento farmacológico , Leucemia-Linfoma de Células T del Adulto/patología , Ratones Endogámicos NOD , Ratones SCID , ApoptosisRESUMEN
Adult T-cell leukemia-lymphoma (ATL) is an aggressive peripheral T-cell neoplasm that develops after long-term infection with human T-cell leukemia virus (HTLV-1). SIRT1, a nicotinamide adenine dinucleotide(+)-dependent histone/protein deacetylase, plays a crucial role in various physiological processes, such as aging, metabolism, neurogenesis and apoptosis, owing to its ability to deacetylate numerous substrates, such as histone and NF-κB, which is implicated as an exacerbation factor in ATL. Here, we assessed how SIRT1 is regulated in primary ATL cells and leukemic cell lines. SIRT1 expression in ATL patients was significantly higher than that in healthy controls, especially in the acute type. Sirtinol, a SIRT1 inhibitor, induced significant growth inhibition or apoptosis in cells from ATL patients and leukemic cell lines, especially HTLV-1-related cell lines. Sirtinol-induced apoptosis was mediated by activation of the caspase family and degradation of SIRT1 in the nucleus. Furthermore, SIRT1 knockdown by SIRT1-specific small interfering RNA caused apoptosis via activation of caspase-3 and PARP in MT-2 cells, HTLV-1-related cell line. These results suggest that SIRT1 is a crucial antiapoptotic molecule in ATL cells and that SIRT1 inhibitors may be useful therapeutic agents for leukemia, especially in patients with ATL.
Asunto(s)
Apoptosis , Benzamidas/farmacología , Leucemia-Linfoma de Células T del Adulto/metabolismo , Naftoles/farmacología , Sirtuina 1/metabolismo , Caspasa 3/metabolismo , Línea Celular Tumoral , Humanos , Leucemia-Linfoma de Células T del Adulto/genética , Poli(ADP-Ribosa) Polimerasas/metabolismo , Interferencia de ARN , ARN Interferente Pequeño , Sirtuina 1/antagonistas & inhibidores , Sirtuina 1/genética , Sirtuinas/antagonistas & inhibidoresRESUMEN
CD300a is a member of CD300 family molecules consisting of seven genes on human chromosome 17 and nine genes in mouse chromosome 11. CD300a has a long cytoplasmic region containing the consensus immunoreceptor tyrosine-based inhibitory motif (ITIM) sequence. Upon crosslinking with antibodies against CD300a, CD300a mediates an inhibitory signal in myeloid cells. However, the ligand for CD300a has not been identified and the physiological role of CD300a remained unclear. Here, we demonstrate that the chimeric fusion protein of CD300a extracellular domain with the Fc portion of human IgG specifically bound phosphatidylserine (PS), which is exposed on the outer leaflet of the plasma membrane of apoptotic cells. PS binding to CD300a induced SHP-1 recruitment by CD300a in mast cells in response to LPS. These results indicated that CD300a is a new PS receptor.
Asunto(s)
Antígenos CD/inmunología , Fosfatidilserinas/inmunología , Receptores Inmunológicos/inmunología , Animales , Antígenos CD/química , Antígenos CD/genética , Membrana Celular/inmunología , Humanos , Fragmentos Fc de Inmunoglobulinas/química , Fragmentos Fc de Inmunoglobulinas/genética , Fragmentos Fc de Inmunoglobulinas/inmunología , Inmunoglobulina G/química , Inmunoglobulina G/genética , Inmunoglobulina G/inmunología , Células Jurkat , Ligandos , Mastocitos/inmunología , Ratones , Estructura Terciaria de Proteína , Receptores Inmunológicos/química , Receptores Inmunológicos/genética , Proteínas Recombinantes de Fusión/química , Proteínas Recombinantes de Fusión/genética , Proteínas Recombinantes de Fusión/inmunologíaRESUMEN
Neurosteroids are synthesized de novo from cholesterol in the brain. In rodents, the Purkinje cell actively produces several kinds of neurosteroids including estradiol during neonatal life, when cerebellar neuronal circuit formation occurs. Estradiol may be involved in cerebellar neuronal circuit formation through promoting neuronal growth and synaptic contact, because the Purkinje cell expresses estrogen receptor-ß. To test this hypothesis, in this study we examined the effect of estradiol on dendritic growth, spinogenesis, and synaptogenesis in the Purkinje cell using neonatal wild-type (WT) mice or cytochrome P450 aromatase knock-out (ArKO) mice. Administration of estradiol to neonatal WT or ArKO mice increased dendritic growth, spinogenesis, and synaptogenesis in the Purkinje cell. In contrast, WT mice treated with tamoxifen, an ER antagonist, or ArKO mice exhibited decreased Purkinje dendritic growth, spinogenesis, and synaptogenesis at the same neonatal period. Estrogen administration to neonatal WT or ArKO mice increased the expression of brain-derived neurotrophic factor (BDNF) in the cerebellum, whereas tamoxifen decreased the BDNF level in WT mice similar to ArKO mice. BDNF administration to tamoxifen-treated WT mice increased Purkinje dendritic growth. These results indicate that estradiol induces dendritic growth, spinogenesis, and synaptogenesis in the developing Purkinje cell via BDNF action during neonatal life.
Asunto(s)
Factor Neurotrófico Derivado del Encéfalo/biosíntesis , Cerebelo/crecimiento & desarrollo , Dendritas/efectos de los fármacos , Espinas Dendríticas/efectos de los fármacos , Estradiol/farmacología , Células de Purkinje/efectos de los fármacos , Sinapsis/efectos de los fármacos , Animales , Animales Recién Nacidos , Factor Neurotrófico Derivado del Encéfalo/fisiología , Cerebelo/citología , Estradiol/análogos & derivados , Humanos , Ratones , Ratones NoqueadosRESUMEN
IgM is an antibody class common to all vertebrates that plays a primary role in host defenses against infection. Binding of IgM with an antigen initiates the complement cascade, accelerating cellular and humoral immune responses. However, the functional role of the Fc receptor for IgM in such immune responses remains obscure. Here we show that mice deficient in Fc alpha/muR, an Fc receptor for IgM expressed on B cells and follicular dendritic cells (FDCs), have enhanced germinal center formation and affinity maturation and memory induction of IgG3(+) B cells after immunization with T-independent (TI) antigens. Moreover, Fc alpha/muR-deficient mice show prolonged antigen retention by marginal zone B (MZB) cells and FDCs. In vitro studies demonstrate that interaction of the IgM immune complex with Fc alpha/muR partly suppress TI antigen retention by MZB cells. We further show that downregulation of complement receptor (CR)1 and CR2 or complement deprivation by in vivo injection with anti-CR1/2 antibody or cobra venom factor attenuates antigen retention by MZB cells and germinal center formation after immunization with TI antigens in Fc alpha/muR(-/-) mice. Taken together, these results suggest that Fc alpha/muR negatively regulates TI antigen retention by MZB cells and FDCs, leading to suppression of humoral immune responses against T-independent antigens.
Asunto(s)
Formación de Anticuerpos/inmunología , Antígenos T-Independientes/inmunología , Receptores Fc/deficiencia , Receptores Fc/inmunología , Animales , Afinidad de Anticuerpos/inmunología , Especificidad de Anticuerpos/inmunología , Linfocitos B/citología , Linfocitos B/inmunología , Proteínas del Sistema Complemento/inmunología , Células Dendríticas Foliculares/citología , Células Dendríticas Foliculares/inmunología , Centro Germinal/citología , Centro Germinal/inmunología , Inmunización , Inmunoglobulina G/inmunología , Memoria Inmunológica , RatonesRESUMEN
Adult T-cell leukemia/lymphoma (ATL) develops after a long period of human T-cell leukemia virus (HTLV)-1 infection and is associated with host aging in addition to genetic abnormalities in HTLV-1 infected cells. SIRT1 is a histone deacetylase involved in cell cycle and apoptosis. We previously showed the high expression of SIRT1 protein in peripheral blood mononuclear cells from patients with ATL. There have been many reports that SIRT1 inhibitors show tumor-suppressive effects. On the other hand, SIRT1 activator SRT1720 induces the cell death of multiple myeloma and breast cancer cells. However, the effect of SRT1720 on ATL is unknown. This study aimed to evaluate the effect of SRT1720 on cell death in leukemic cell lines in vitro and freshly isolated ATL cells ex vivo and in an ATL in vivo mouse model. SRT1720 reduced cell viability in vitro and ex vivo. Additionally, SRT1720 increased the number of apoptotic cells, as shown by annexin V positive cells, cleaved poly (ADP-ribose) polymerase 1, cleaved caspase-3, and fragmented DNA. SRT1720 also induced mitochondrial outer membrane permeabilization with the generation of mitochondrial reactive oxygen species and autophagy. However, SIRT1 knockdown did not attenuate SRT1720-induced cell death in leukemic cell lines. Finally, SRT1720 treatment decreased the growth of human ATL tumor xenografts in immunodeficient mice. Our study shows that while SRT1720 does not target SIRT1, it induces cell death in ATL cells via apoptosis and autophagy and has antitumor activity.
Asunto(s)
Compuestos Heterocíclicos de 4 o más Anillos , Leucemia-Linfoma de Células T del Adulto , Animales , Apoptosis , Muerte Celular , Compuestos Heterocíclicos de 4 o más Anillos/farmacología , Humanos , Leucemia-Linfoma de Células T del Adulto/tratamiento farmacológico , Leucemia-Linfoma de Células T del Adulto/genética , Leucemia-Linfoma de Células T del Adulto/metabolismo , Leucocitos Mononucleares/metabolismo , Ratones , Sirtuina 1/genética , Sirtuina 1/metabolismoRESUMEN
As brain testosterone plays both androgenic and estrogenic actions due to its conversion into estrogen via aromatase naturally, it is unclear that the age-related reduction of testosterone increased risk of Alzheimer's disease (AD) in men is mediated through androgen alone or both androgen and estrogen mechanisms. Our previous studies using a gene-based approach in mouse model to block the conversion of testosterone into estrogen (aromatase gene knock-out, ArKO), found a depletion of estrogen and increase in testosterone endogenously in males. Here, we use crossing the ArKO mice with APP23 transgenic mice, a mouse model of AD, to produce APP23/Ar(+/-) mice to study the estrogen-independent effect of testosterone on AD. We found a significant reduction in brain plaque formation, improved cognitive function and increase NEP activity in male APP23/Ar(+/-) mice compared with age-matched male APP23 controls. In addition, we found, for the first time, a reduction of beta-secretase (BACE1) enzyme activity, mRNA level and protein expression in the male APP23/Ar(+/-) mice, suggesting that endogenous testosterone, independent from estrogen, may protect against AD in males via two major mechanisms, downregulation of BACE1 activities at transcriptional level to reduce beta amyloid production and upregulation of NEP activities to enhance bate amyloid degradation.
Asunto(s)
Enfermedad de Alzheimer , Secretasas de la Proteína Precursora del Amiloide/metabolismo , Precursor de Proteína beta-Amiloide/genética , Aromatasa/genética , Ácido Aspártico Endopeptidasas/metabolismo , Trastornos del Conocimiento/etiología , Regulación hacia Abajo/genética , Factores de Edad , Enfermedad de Alzheimer/complicaciones , Enfermedad de Alzheimer/metabolismo , Enfermedad de Alzheimer/patología , Secretasas de la Proteína Precursora del Amiloide/genética , Péptidos beta-Amiloides/metabolismo , Animales , Aromatasa/deficiencia , Ácido Aspártico Endopeptidasas/genética , Encéfalo/metabolismo , Encéfalo/patología , Trastornos del Conocimiento/genética , Modelos Animales de Enfermedad , Ensayo de Inmunoadsorción Enzimática/métodos , Estrógenos/metabolismo , Conducta Exploratoria/fisiología , Humanos , Insulisina/metabolismo , Masculino , Aprendizaje por Laberinto/fisiología , Memoria/fisiología , Ratones , Ratones Endogámicos C57BL , Ratones Transgénicos , Mutación/genética , Neprilisina/metabolismo , Fosfopiruvato Hidratasa/metabolismo , ARN Mensajero/metabolismo , Radioinmunoensayo/métodos , Estadísticas no Paramétricas , Testosterona/metabolismoRESUMEN
Upon antigen recognition by the T cell receptor, lymphocyte function-associated antigen 1 (LFA-1) physically associates with the leukocyte adhesion molecule CD226 (DNAM-1) and the protein tyrosine kinase Fyn. We show that lentiviral vector-mediated mutant (Y-F322) CD226 transferred into naive CD4+ helper T cells (Ths) inhibited interleukin (IL)-12-independent Th1 development initiated by CD3 and LFA-1 ligations. Moreover, proliferation induced by LFA-1 costimulatory signal was suppressed in mutant (Y-F322) CD226-transduced naive CD4+ and CD8+ T cells in the absence of IL-2. These results suggest that CD226 is involved in LFA-1-mediated costimulatory signals for triggering naive T cell differentiation and proliferation. We also demonstrate that although LFA-1, CD226, and Fyn are polarized at the immunological synapse upon stimulation with anti-CD3 in CD4+ and CD8+ T cells, lipid rafts are polarized in CD4+, but not CD8+, T cells. Moreover, proliferation initiated by LFA-1 costimulatory signal is suppressed by lipid raft disruption in CD4+, but not CD8+, T cells, suggesting that the LFA-1 costimulatory signal is independent of lipid rafts in CD8+ T cells.
Asunto(s)
Antígenos de Diferenciación de Linfocitos T/fisiología , Antígeno-1 Asociado a Función de Linfocito/fisiología , Linfocitos T/fisiología , Diferenciación Celular , División Celular , Transferencia de Gen Horizontal , Vectores Genéticos , Humanos , Interleucina-12/fisiología , Interleucina-2/farmacología , Lentivirus/genética , Activación de Linfocitos , Microdominios de Membrana/fisiología , Células TH1/fisiologíaRESUMEN
Immune responses are regulated by opposing positive and negative signals triggered by the interaction of activating and inhibitory cell surface receptors with their ligands. Here, we describe novel paired activating and inhibitory immunoglobulin-like receptors, designated myeloid-associated immunoglobulin-like receptor (MAIR) I and MAIR-II, whose extracellular domains are highly conserved by each other. MAIR-I, expressed on the majority of myeloid cells, including macrophages, granulocytes, mast cells, and dendritic cells, contains the tyrosine-based sorting motif and the immunoreceptor tyrosine-based inhibitory motif-like sequences in the cytoplasmic domain and mediates endocytosis of the receptor and inhibition of IgE-mediated degranulation from mast cells. On the other hand, MAIR-II, expressed on subsets of peritoneal macrophages and B cells, associates with the immunoreceptor tyrosine-based activation motif-bearing adaptor DAP12 and stimulates proinflammatory cytokines and chemokine secretions from macrophages. Thus, MAIR-I and MAIR-II play important regulatory roles in cell signaling and immune responses.