RESUMO
Digital technologies have the potential to improve the quality of nursing care. CARE REGIO is a Bavarian joint research project for digital transformation and technology in nursing care. The project goals are supporting the nursing staff, saving time, improving the quality of care as well as increasing the quality of life and safety of those in need of care. In Phase 1 of the project, literature and stakeholder analyses, and qualitative surveys were carried out. Subsequently, central fields of action were defined for Phase 2 of the project. CARE REGIO can make a significant contribution to evaluating existing digital solutions, developing new solutions, and accelerating their implementation into practice.
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Qualidade de Vida , Tecnologia , Humanos , Inquéritos e QuestionáriosRESUMO
Leukemia stem cells are known to exhibit multidrug resistance by expression of ATP-binding cassette (ABC) transporters which constitute transmembrane proteins capable of exporting a wide variety of chemotherapeutic drugs from the cytosol. We show here that human promyeloblastic leukemia KG-1a cells exposed to the histone deacetylase inhibitor phenylbutyrate resemble many characteristics of leukemia stem cells, including expression of functional ABC transporters such as P-glycoprotein, BCRP and MRP8. Consequently, KG-1a cells display resistance to the induction of apoptosis by various chemotherapeutic drugs. Resistance to apoptosis induction by chemotherapeutic drugs can be reversed by cyclosporine A, which effectively inhibits the activity of P-glycoprotein and BCRP, thus demonstrating ABC transporter-mediated drug resistance in KG-1a cells. However, KG-1a are highly sensitive to apoptosis induction by salinomycin, a polyether ionophore antibiotic that has recently been shown to kill human breast cancer stem cell-like cells and to induce apoptosis in human cancer cells displaying multiple mechanisms of drug and apoptosis resistance. Whereas KG-1a cells can be adapted to proliferate in the presence of apoptosis-inducing concentrations of bortezomib and doxorubicin, salinomycin does not permit long-term adaptation of the cells to apoptosis-inducing concentrations. Thus, salinomycin should be regarded as a novel and effective agent for the elimination of leukemia stem cells and other tumor cells exhibiting ABC transporter-mediated multidrug resistance.
Assuntos
Transportadores de Cassetes de Ligação de ATP/metabolismo , Resistência a Múltiplos Medicamentos/efeitos dos fármacos , Resistencia a Medicamentos Antineoplásicos/efeitos dos fármacos , Leucemia Mieloide Aguda/metabolismo , Células-Tronco Neoplásicas/efeitos dos fármacos , Piranos/farmacologia , Linhagem Celular Tumoral , HumanosRESUMO
We have previously shown that inhibition of the proteolytic activity of the proteasome induces apoptosis and suppresses essential functions of activated human CD4(+) T cells, and we report now the detailed mechanisms of apoptosis following proteasome inhibition in these cells. Here we show that proteasome inhibition by bortezomib activates the mitochondrial pathway of apoptosis in activated CD4(+) T cells by disrupting the equilibrium of pro-apoptotic and anti-apoptotic proteins at the outer mitochondrial membrane (OMM) and by inducing the generation of reactive oxygen species (ROS). Proteasome inhibition leads to accumulation of pro-apoptotic proteins PUMA, Noxa, Bim and p53 at the OMM. This event provokes mitochondrial translocation of activated Bax and Bak homodimers, which induce loss of mitochondrial membrane potential (DeltaPsim). Breakdown of DeltaPsim is followed by rapid release of pro-apoptotic Smac/DIABLO and HtrA2 from mitochondria, whereas release of cytochrome c and AIF is delayed. Cytoplasmic Smac/DIABLO and HtrA2 antagonize IAP-mediated inhibition of partially activated caspases, leading to premature activation of caspase-3 followed by activation of caspase-9. Our data show that proteasome inhibition triggers the mitochondrial pathway of apoptosis by activating mutually independent apoptotic pathways. These results provide novel insights into the mechanisms of apoptosis induced by proteasome inhibition in activated T cells and underscore the future use of proteasome inhibitors for immunosuppression.
Assuntos
Apoptose , Linfócitos T CD4-Positivos/patologia , Regulação Enzimológica da Expressão Gênica , Mitocôndrias/metabolismo , Inibidores de Proteassoma , Ácidos Borônicos/farmacologia , Bortezomib , Linfócitos T CD4-Positivos/metabolismo , Caspase 3/metabolismo , Caspase 9/metabolismo , Citocromos c/metabolismo , Células Dendríticas/citologia , Dimerização , Ativação Enzimática , Humanos , Potenciais da Membrana , Inibidores de Proteases/farmacologia , Complexo de Endopeptidases do Proteassoma/metabolismo , Pirazinas/farmacologiaRESUMO
Salinomycin is a polyether antibiotic isolated from Streptomyces albus that acts in different biological membranes as a ionophore with a preference for potassium. It is widely used as an anticoccidial drug in poultry and is fed to ruminants to improve nutrient absorption and feed efficiency. Salinomycin has recently been shown to selectively deplete human breast cancer stem cells from tumorspheres and to inhibit breast cancer growth and metastasis in mice. We show here that salinomycin induces massive apoptosis in human cancer cells of different origin, but not in normal cells such as human T lymphocytes. Moreover, salinomycin is able to induce apoptosis in cancer cells that exhibit resistance to apoptosis and anticancer agents by overexpression of Bcl-2, P-glycoprotein or 26S proteasomes with enhanced proteolytic activity. Salinomycin activates a distinct apoptotic pathway that is not accompanied by cell cycle arrest and that is independent of tumor suppressor protein p53, caspase activation, the CD95/CD95L system and the proteasome. Thus, salinomycin should be considered as a novel and effective anticancer agent that overcomes multiple mechanisms of apoptosis resistance in human cancer cells.
Assuntos
Antibióticos Antineoplásicos/farmacologia , Apoptose , Neoplasias/metabolismo , Piranos/farmacologia , Membro 1 da Subfamília B de Cassetes de Ligação de ATP/biossíntese , Animais , Linhagem Celular Tumoral , Resistencia a Medicamentos Antineoplásicos , Humanos , Camundongos , Complexo de Endopeptidases do Proteassoma/biossíntese , Proteínas Proto-Oncogênicas c-bcl-2/biossínteseRESUMO
Zanthoxylum zanthoxyloides is a West African forest tree that is used for example against malaria and sickle cell anemia in Burkina Faso. The goal of this study was to analyze the genetic and morphological diversity of the species within wild populations in Burkina Faso, where it is potentially under threat due to the uncontrolled harvesting of its roots. Seventy-two trees from three different sites in Southwestern Burkina Faso were analyzed. Each tree was characterized by 12 traits specifying the period of flowering and maturity as well as morphological characteristics of the stem, leaves, and seeds. The molecular analysis was performed using two plastid DNA regions (psbA-trnH and trnL-trnF) and two nuclear regions (GBSSI and ITS) to identify the genetic diversity of the species for further development of a management plan for ex situ reproduction and in situ conservation. We found variability in morphological traits correlating with the geographic distance of the study sites. The molecular analysis, in contrast, revealed hardly any genetic variability among the tested trees and no population structure. Whether the differences in morphological traits are caused by different environmental conditions or by genetic variability in genes linked to morphological traits needs further testing. The apparent lack of genetic differentiation suggests that germplasm throughout the study region is suitable for planting in conservation actions. Efficient conservation management should involve local communities, especially those interested in traditional medicine.
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The highly conserved ubiquitin-proteasome system is the principal machinery for extralysosomal protein degradation in eukaryotic cells. The 26S proteasome, a large multicatalytic multisubunit protease that processes cell proteins by limited and controlled proteolysis, constitutes the central proteolytic component of the ubiquitin-proteasome system. By processing cell proteins essential for development, differentiation, proliferation, cell cycling, apoptosis, gene transcription, signal transduction, senescence, and inflammatory and stress response, the 26S proteasome plays a key role in the regulation and maintenance of basic cellular processes. Various synthetic and biologic inhibitors with different inhibitory profiles towards the proteolytic activities of the 26S proteasome have been identified recently. Such proteasome inhibitors induce apoptosis and cell cycle arrest preferentially in neoplastic cells. Based on these findings proteasome inhibitors became useful in cancer therapy. However, under the pressure of continuous proteasome inhibition, eukaryotic cells can develop complex adaptive mechanisms to subvert the lethal attack of proteasome inhibitors. Such mechanisms include the adaptive modification of the proteasome system with increased expression, enhanced proteolytic activity and altered subcomplex assembly and subunit composition of proteasomes as well as the expression of a giant oligomeric protease complex, tripeptidyl peptidase II, which partially compensates for impaired proteasome function. Here we review the adaptive mechanisms developed by eukaryotic cells in response to proteasome inhibition. These mechanisms reveal enormous flexibility of the proteasome system and may have implications in cancer biology and therapy.
Assuntos
Complexo de Endopeptidases do Proteassoma/metabolismo , Inibidores de Proteassoma , Animais , Apoptose/efeitos dos fármacos , Humanos , Modelos Biológicos , Neoplasias/tratamento farmacológico , Ubiquitina/química , Ubiquitina/metabolismoRESUMO
The proteasome constitutes the central proteolytic component of the highly conserved ubiquitin-proteasome system, which is required for the maintenance and regulation of basic cellular processes, including differentiation, proliferation, cell cycling, gene transcription and apoptosis. Here we show that inhibition of proteasomal proteolytic activity by the proteasome inhibitors bortezomib and lactacystin suppresses essential immune functions of human CD4(+) T cells activated by allogeneic dendritic cells (DCs). In activated CD4(+) T cells, proteasome inhibition induces apoptosis accompanied by rapid accumulation and stabilization of the tumour suppressor protein p53. Activated CD4(+) T cells surviving proteasome inhibition undergo inhibition of proliferation by induction of G(1) phase cell-cycle arrest. Induction of G(1) arrest is accompanied by the accumulation of cyclin-dependent kinase inhibitors p21(WAF1/CIP1) and p27(KIP1) and the disappearance of cyclin A, cyclin D2 and proliferating cell nuclear antigen, proteins known to regulate G(1) to S phase cell-cycle transitions. Expression of the activation-associated cell surface receptors CD25, CD28, CD120b and CD134 as well as production of interferon-gamma (IFN-gamma), tumour necrosis factor-alpha (TNF-alpha), interleukin-4 (IL-4) and IL-5 is suppressed in response to proteasome inhibition in CD4(+) T cells activated by DCs. Expression of CD25, IFN-gamma, TNF-alpha, IL-4 and IL-5 is known to be mediated by the transcriptional activity of nuclear factor of activated T cells (NFAT), and we show here that proteasome inhibition suppresses activation and nuclear translocation of NFATc2 in activated CD4(+) T cells. Thus, the proteasome is required for essential immune functions of activated CD4(+) T cells and can be defined as a molecular target for the suppression of deregulated and unwanted T-cell-mediated immune responses.
Assuntos
Linfócitos T CD4-Positivos/efeitos dos fármacos , Imunossupressores/farmacologia , Inibidores de Proteases/farmacologia , Inibidores de Proteassoma , Acetilcisteína/análogos & derivados , Acetilcisteína/farmacologia , Antígenos CD/metabolismo , Apoptose/efeitos dos fármacos , Apoptose/imunologia , Ácidos Borônicos/farmacologia , Bortezomib , Linfócitos T CD4-Positivos/imunologia , Ciclo Celular/efeitos dos fármacos , Proteínas de Ciclo Celular/metabolismo , Proliferação de Células/efeitos dos fármacos , Células Cultivadas , Citocinas/biossíntese , Relação Dose-Resposta Imunológica , Humanos , Ativação Linfocitária/efeitos dos fármacos , Ativação Linfocitária/imunologia , Fatores de Transcrição NFATC/metabolismo , Complexo de Endopeptidases do Proteassoma/imunologia , Pirazinas/farmacologia , Translocação Genética/efeitos dos fármacos , Proteína Supressora de Tumor p53/metabolismoRESUMO
Simvastatin is a competitive inhibitor of HMG-CoA reductase, the rate-limiting enzyme of the mevalonate pathway required for the biosynthesis of cholesterol and higher isoprenoids such as geranylgeranyl pyrophosphate (GGPP). Apart from its capacity to lower cholesterol plasma levels and to protect against cardiovascular disease, simvastatin induces apoptosis in various cancer cells. We have generated human Namalwa Burkitt lymphoma cells that display general apoptosis resistance and hyperproliferation due to increased expression and proteolytic activity of 26S proteasomes in response to continuous treatment of the cells with the proteasome inhibitor bortezomib. In these cells, simvastatin does not inhibit proteasome activity, but induces apoptosis, G2/M cell cycle arrest and accumulation of p21(Waf1/Cip1), and effectively inhibits hyperproliferation. These effects are reversed by the addition of GGPP. GGPP-dependent plasma membrane localization of the small GTPase RhoA that is required for RhoA-mediated oncogenic signaling is completely inhibited by simvastatin. Finally, bortezomib but not simvastatin induces accumulation and stabilization of the anti-apoptotic protein Mcl-1, which is known to confer resistance to apoptosis in cancer cells. Thus, simvastatin overcomes bortezomib-induced apoptosis resistance by inhibiting synthesis of GGPP and disrupting a GGPP-dependent survival pathway.
Assuntos
Apoptose/efeitos dos fármacos , Linfoma de Burkitt/metabolismo , Inibidores de Hidroximetilglutaril-CoA Redutases/farmacologia , Fosfatos de Poli-Isoprenil/metabolismo , Sinvastatina/farmacologia , Antineoplásicos/farmacologia , Ácidos Borônicos/farmacologia , Bortezomib , Divisão Celular/efeitos dos fármacos , Linhagem Celular , Membrana Celular/efeitos dos fármacos , Membrana Celular/enzimologia , Proliferação de Células/efeitos dos fármacos , Sobrevivência Celular/efeitos dos fármacos , Inibidor de Quinase Dependente de Ciclina p21/metabolismo , Resistencia a Medicamentos Antineoplásicos/efeitos dos fármacos , Fase G2/efeitos dos fármacos , Humanos , Proteína de Sequência 1 de Leucemia de Células Mieloides , Proteínas Proto-Oncogênicas c-bcl-2/metabolismo , Pirazinas/farmacologia , Proteína rhoA de Ligação ao GTP/metabolismoRESUMO
The sense of balance, which is usually barely noticeable in the background of each of our movements, only becomes manifest in its function during intense stimulation or in the event of illness, which may quite literally turn your world upside down. While it is true that balance is becoming a bigger issue, that is mainly because people are losing it more frequently. So why is balance not as commonly talked about in psychology, medicine or the arts as the other five traditional senses? This is partly due to its unusual multi-modal nature, whereby three sensory inputs are coordinated and integrated by the central nervous system. Without it, however, we might not have much use for the other senses. The sense of balance encompasses the bodily experience in its entirety. Not only do we act with the body, we may also think and feel through it and with it. Bodily states are not simply effects of cognition; they cause it as well. Equilibrioception is an essential sense and it is interconnected with a wide range of other areas, including cognition, perception, embodiment, the autonomic nervous system, aesthetics, the arts, and education.
RESUMO
BACKGROUND: The polyclonal rabbit antithymocyte and anti-T-cell immunoglobulins (ATGs) Thymoglobulin (TG) and ATG-Fresenius S (ATG-F) have been widely used for the prevention and therapy of allograft rejection and graft versus host disease in transplantation. Although immunosuppressive mechanisms of ATGs on T cells are well studied, less is known about their impact on dendritic cells (DCs). METHODS: Effects of TG and ATG-F on immune functions and signaling pathways of human monocyte-derived DCs were determined by flow cytometry, enzyme-linked immunosorbent assay, Western blot, apoptosis assays, endocytosis assays, and T cell stimulation assays. RESULTS: TG and ATG-F bind rapidly and with high affinity to CD11c, CD80, CD86, CD40, CD36, CD38, CD206, and human leukocyte antigen-DR on DCs. TG and, to a lesser extent, ATG-F induce apoptosis in immature and mature DCs. Macropinocytotic and receptor-mediated endocytotic antigen uptake in immature DCs is inhibited by TG and ATG-F due to their binding of the C-type lectins CD206 and CD209. TG and ATG-F induce activation of the mitogen-activated protein kinases ERK1/2 and p38 that contributes to the induction of apoptosis. TG and ATG-F also induce cytoplasmic-nuclear translocation of the NF-kappaB/Rel transcription factors RelB, RelA, p50, and p52. Production of interleukin-12p70 in mature DCs is suppressed by TG and ATG-F. TG and ATG-F reduce the capacity of mature DCs to stimulate allogeneic and autologous T cells. CONCLUSIONS: ATGs interfere with basic DC functions, suggesting that DCs are relevant targets for the immunosuppressive action of ATGs in transplantation.
Assuntos
Soro Antilinfocitário/imunologia , Células Dendríticas/imunologia , Anticorpos Monoclonais/imunologia , Apoptose , Diferenciação Celular , Células Cultivadas , Células Dendríticas/citologia , Células Dendríticas/metabolismo , Endocitose , Humanos , Interleucina-12/biossíntese , Cinética , Proteínas Quinases Ativadas por Mitógeno/metabolismo , NF-kappa B/metabolismo , Proteínas Proto-Oncogênicas c-rel/metabolismo , Receptores de Antígenos/imunologiaRESUMO
The high-mobility group box 1 (HMGB1) protein has a central role in immunological antitumour defense. Here we show that natural killer cell-derived HMGB1 directly eliminates cancer cells by triggering metabolic cell death. HMGB1 allosterically inhibits the tetrameric pyruvate kinase isoform M2, thus blocking glucose-driven aerobic respiration. This results in a rapid metabolic shift forcing cells to rely solely on glycolysis for the maintenance of energy production. Cancer cells can acquire resistance to HMGB1 by increasing glycolysis using the dimeric form of PKM2, and employing glutaminolysis. Consistently, we observe an increase in the expression of a key enzyme of glutaminolysis, malic enzyme 1, in advanced colon cancer. Moreover, pharmaceutical inhibition of glutaminolysis sensitizes tumour cells to HMGB1 providing a basis for a therapeutic strategy for treating cancer.
Assuntos
Neoplasias do Colo/metabolismo , Neoplasias do Colo/fisiopatologia , Proteína HMGB1/metabolismo , Proteínas de Transporte/genética , Proteínas de Transporte/metabolismo , Morte Celular , Linhagem Celular Tumoral , Respiração Celular , Neoplasias do Colo/enzimologia , Neoplasias do Colo/genética , Glucose/metabolismo , Glicólise , Proteína HMGB1/genética , Humanos , Proteínas de Membrana/genética , Proteínas de Membrana/metabolismo , Hormônios Tireóideos/genética , Hormônios Tireóideos/metabolismo , Proteínas de Ligação a Hormônio da TireoideRESUMO
Salinomycin is a monocarboxylic polyether ionophore isolated from Streptomyces albus that has been used for more than 30 years as an agricultural antibiotic to prevent coccidiosis in poultry and to improve nutrient absorption and feed efficiency in ruminants and swine. As a inonophore with strict selectivety for alkali ions and a strong preference for potassium, salinomycin interferes with transmembrane potassium potential and promotes the efflux of K+ ions from mitochondria and cytoplasm. Salinomycin has recently been shown to kill human cancer stem cells and to inhibit breast cancer growth and metastasis in mice. Salinomycin is also able to induce massive apoptosis in human cancer cells of different origins that display multiple mechanisms of drug and apoptosis resistance. Salinomycin activates an unconventional pathway of apoptosis in human cancer cells that may contribute to the breakdown of apoptosis resistance. The ability of salinomycin to effectively kill both cancer stem cells and apoptosis-resistant cancer cells may define the compound as a novel and effective anticancer agent.
RESUMO
Helenalin is a naturally occuring sesquiterpene lactone extracted from Arnica montana and Arnica chamissonis ssp. foliosa. Helenalin and its derivatives are known for anti-cancer and anti-inflammatory effects via inhibiting NF-kappaB and telomerase activity and impairing protein and DNA synthesis, suggesting that helenalin is a potential candidate for the treatment of deregulated and unwanted T cell-mediated immune responses. Here we show that helenalin induces apoptosis in activated CD4+ T cells by triggering the mitochondrial pathway of apoptosis. Induction of apoptosis is accompanied by rapid stabilization of p53, nuclear localization of p53 and AIF, and an increase in ROS production that results in loss of mitochondrial membrane potential (DeltaPsim). Activated CD4+ T cells which survive exposure to helenalin undergo inhibition of proliferation by induction of G2/M cell cycle arrest. Cell cycle arrest is accompanied by the accumulation of cell cycle regulator proteins p21(WAF/CIP1), p2(KIP1) and cyclin D2, whereas abundance of cyclin A and B(1) is decreased. Cell surface expression of the activation-associated receptors CD25, CD27, CD28, CD120b as well as production of IL-2 are impaired. Transcriptional activation of genes encoding for CD25, IL-2 and IFN-gamma is mediated by transcription factors of the NFAT family, and we demonstrate that helenalin suppresses nuclear translocation of NFATc2 in activated CD4+ T cells. Thus, helenalin can be defined as a new immunosuppressive compound suited for the treatment of deregulated and unwanted T cell-mediated immune responses.
Assuntos
Antineoplásicos Fitogênicos/farmacologia , Apoptose/imunologia , Linfócitos T CD4-Positivos/efeitos dos fármacos , Sesquiterpenos/farmacologia , Antígenos CD/efeitos dos fármacos , Antígenos CD/imunologia , Antígenos CD/metabolismo , Apoptose/efeitos dos fármacos , Fator de Indução de Apoptose/imunologia , Fator de Indução de Apoptose/metabolismo , Linfócitos T CD4-Positivos/imunologia , Proteínas de Ciclo Celular/efeitos dos fármacos , Proteínas de Ciclo Celular/imunologia , Proteínas de Ciclo Celular/metabolismo , Proliferação de Células/efeitos dos fármacos , Humanos , Interferon gama/imunologia , Interferon gama/metabolismo , Interleucina-2/antagonistas & inibidores , Interleucina-2/imunologia , Interleucina-2/metabolismo , Células Jurkat , Ativação Linfocitária/imunologia , Potencial da Membrana Mitocondrial/efeitos dos fármacos , Potencial da Membrana Mitocondrial/fisiologia , NF-kappa B/antagonistas & inibidores , NF-kappa B/imunologia , NF-kappa B/metabolismo , Fatores de Transcrição NFATC/efeitos dos fármacos , Fatores de Transcrição NFATC/imunologia , Fatores de Transcrição NFATC/metabolismo , Complexo de Endopeptidases do Proteassoma/imunologia , Complexo de Endopeptidases do Proteassoma/metabolismo , Proteínas Proto-Oncogênicas c-bcl-2/genética , Proteínas Proto-Oncogênicas c-bcl-2/imunologia , Proteínas Proto-Oncogênicas c-bcl-2/metabolismo , Espécies Reativas de Oxigênio/imunologia , Espécies Reativas de Oxigênio/metabolismo , Sesquiterpenos de Guaiano , Proteína Supressora de Tumor p53/imunologia , Proteína Supressora de Tumor p53/metabolismoRESUMO
The proteasome is the main protease for extralysosomal protein degradation in eukaryotic cells, and constitutes a sophisticated high molecular mass proteinase complex underlying a tightly coordinated expression and assembly of multiple subunits and subcomplexes. Here we show that continuous inhibition of proteasomal chymotrypsin-like peptidase activity by the proteasome inhibitor bortezomib induces in human Namalwa Burkitt lymphoma cells increased de novo biogenesis of proteasomes accompanied by increased expression of the proteasome maturation protein POMP, increased expression of 19S-20S-19S proteasomes, and abrogation of expression of beta 1i, beta 2i and beta 5i immunosubunits and PA28 in favor of increased expression of constitutive proteolytic beta1, beta2 and beta 5 subunits and 19S regulatory complexes. These alterations of proteasome expression and subunit composition are accompanied by an increase in proteasomal caspase-like, trypsin-like and chymotrypsin-like peptidase activities, not inhibitable by high doses of bortezomib. Cells harboring these proteasomal alterations display rapid proliferation and cell cycle progression, and acquire resistance to apoptosis induced by proteasome inhibitors, gamma-irradiation and staurosporine. This acquired apoptosis resistance is accompanied by de novo expression of anti-apoptotic Hsp27 protein and the loss of ability to accumulate and stabilize pro-apoptotic p53 protein. Thus, increased expression, altered subunit composition and increased activity of proteasomes constitute a hitherto unknown adaptive and autoregulatory feedback mechanism to allow cells to survive the lethal challenge of proteasome inhibition and to establish a hyperproliferative and apoptosis-resistant phenotype.
Assuntos
Apoptose/efeitos dos fármacos , Linfoma de Burkitt/enzimologia , Linfoma de Burkitt/patologia , Complexo de Endopeptidases do Proteassoma/metabolismo , Inibidores de Proteassoma , Membro 1 da Subfamília B de Cassetes de Ligação de ATP/metabolismo , Ácidos Borônicos/farmacologia , Bortezomib , Linhagem Celular Tumoral , Proliferação de Células/efeitos dos fármacos , Ativação Enzimática/efeitos dos fármacos , Glicoproteínas/metabolismo , Proteínas de Choque Térmico HSP27 , Proteínas de Choque Térmico/metabolismo , Humanos , Chaperonas Moleculares , Proteínas de Neoplasias/metabolismo , Poliubiquitina/metabolismo , Inibidores de Proteases/farmacologia , Subunidades Proteicas/metabolismo , Pirazinas/farmacologia , Proteína Supressora de Tumor p53/metabolismo , UbiquitinaçãoRESUMO
The ubiquitin-proteasome pathway is the principal system for extralysosomal protein degradation in eukaryotic cells, and is essential for the regulation and maintenance of basic cellular processes, including differentiation, proliferation, cell cycling, gene transcription and apoptosis. The 26S proteasome, a large multicatalytic protease complex, constitutes the system's proteolytic core machinery that exhibits different proteolytic activities residing in defined proteasomal subunits. We have identified proteasome inhibitors - bortezomib, epoxomicin and lactacystin - which selectively inhibit the proteasomal beta5 subunit-located chymotrypsin-like peptidase activity in human monocyte-derived dendritic cells (DCs). Inhibition of proteasomal chymotrypsin-like peptidase activity in immature and mature DCs impairs the cell-surface expression of CD40, CD86, CD80, human leucocyte antigen (HLA)-DR, CD206 and CD209, induces apoptosis, and impairs maturation of DCs, as demonstrated by decreased cell-surface expression of CD83 and lack of nuclear translocation of RelA and RelB. Inhibition of chymotrypsin-like peptidase activity abrogates macropinocytosis and receptor-mediated endocytosis of macromolecular antigens in immature DCs, and inhibits the synthesis of interleukin (IL)-12p70 and IL-12p40 in mature DCs. As a functional consequence, DCs fail to stimulate allogeneic CD4(+) and CD8(+) T cells and autologous CD4(+) T cells sufficiently in response to inhibition of chymotrypsin-like peptidase activity. Thus, proteasomal chymotrypsin-like peptidase activity is required for essential functions of human DCs, and inhibition of proteasomal chymotrypsin-like peptidase activity by selective inhibitors, or by targeting beta5 subunit expression, may provide a novel therapeutic strategy for suppression of deregulated and unwanted immune responses.
Assuntos
Quimases/metabolismo , Células Dendríticas/imunologia , Complexo de Endopeptidases do Proteassoma/imunologia , Acetilcisteína/análogos & derivados , Acetilcisteína/farmacologia , Apoptose/efeitos dos fármacos , Apoptose/imunologia , Ácidos Borônicos/farmacologia , Bortezomib , Diferenciação Celular/efeitos dos fármacos , Diferenciação Celular/imunologia , Quimases/antagonistas & inibidores , Quimases/imunologia , Inibidores de Cisteína Proteinase/farmacologia , Células Dendríticas/enzimologia , Endocitose/efeitos dos fármacos , Endocitose/imunologia , Humanos , Interleucina-12/biossíntese , Ativação Linfocitária/efeitos dos fármacos , Ativação Linfocitária/imunologia , Monócitos/citologia , Oligopeptídeos/farmacologia , Pinocitose/efeitos dos fármacos , Pinocitose/imunologia , Inibidores de Proteases/farmacologia , Pirazinas/farmacologia , Receptores de Superfície Celular/metabolismoRESUMO
The epidermal growth factor receptor (EGFR) is a member of the erbB tyrosine kinase family of receptors. For many years it has been believed that receptor activation occurs via a monomer-dimer transition that is associated with a conformational change to activate the kinase. However, little is known about the quaternary state of the receptor at normal levels of expression (<10(5) receptors/cell). We employed multidimensional microscopy techniques to gain insight into the state of association of the human EGFR, in the absence and presence of ligand, on the surface of intact BaF/3 cells (50,000 receptors/cell). Image correlation microscopy of an EGFR-enhanced green fluorescent protein chimera was used to establish an average degree of aggregation on the submicron scale of 2.2 receptors/cluster in the absence of ligand increasing to 3.7 receptors/cluster in the presence of ligand. Energy transfer measurements between mixtures of fluorescein isothiocyanate-EGF and Alexa 555-EGF were performed using fluorescence lifetime imaging microscopy as a function of the donor: acceptor labeling ratio to gain insight into the spatial disposition of EGFR ligand binding sites on the nanometer scale. In the context of a two-state Förster resonance energy transfer (FRET)/non-FRET model, the data are consistent with a minimum transfer efficiency of 75% in the FRET population. The microscopy data are related to biophysical data on the EGFR in the A431 cell line and the three-dimensional structure of the ligated EGFR extracellular domain. In the context of a monomer-dimer-oligomer model, the biophysical data are consistent with a significant fraction of ligated EGFR tetramers comprising two dimers juxtaposed in a side-by-side (or slightly staggered) arrangement. Our data are consistent with a specific higher order association of the ligand-bound EGFR on the nanometer scale and indicate the existence of distinct signaling entities beyond the level of the EGFR dimer which could play an important role in receptor transactivation.