RESUMO
The existence of charge-density-wave (CDW) correlations in cuprate superconductors has now been established. However, the nature of the CDW ground state has remained uncertain because disorder and the presence of superconductivity typically limit the CDW correlation lengths to only a dozen unit cells or less. Here we explore the field-induced 3D CDW correlations in extremely pure detwinned crystals of YBa2Cu3O2 (YBCO) ortho-II and ortho-VIII at magnetic fields in excess of the resistive upper critical field ([Formula: see text]) where superconductivity is heavily suppressed. We observe that the 3D CDW is unidirectional and possesses a long in-plane correlation length as well as significant correlations between neighboring CuO2 planes. It is significant that we observe only a single sharply defined transition at a critical field proportional to [Formula: see text], given that the field range used in this investigation overlaps with other high-field experiments including quantum oscillation measurements. The correlation volume is at least two to three orders of magnitude larger than that of the zero-field CDW. This is by far the largest CDW correlation volume observed in any cuprate crystal and so is presumably representative of the high-field ground state of an "ideal" disorder-free cuprate.
RESUMO
OBJECTIVES: The aims of this study were to investigate the prevalence of sleep bruxism in children in Japan, and its relationships with sleep-related factors and daytime problematic behavior. SUBJECTS AND METHODS: Guardians of 6023 children aged 2-12 years completed the Japanese Sleep Questionnaire. Multiple regression analysis and structural equation modeling were performed. RESULTS: Sleep bruxism was reported in 21.0% children (n = 1263): the prevalence was highest in the age group of 5-7 years (27.4%). Multiple regression analysis showed that sleep bruxism had significant correlations with age 5-7 years (OR: 1.72; P < 0.0001), 'Moves a lot during sleep' (OR: 1.47; P < 0.0001), 'sleeps with mouth open' (OR: 1.56; P < 0.0001), and 'snores loudly' (OR: 1.80; P < 0.0001). In structural equation modeling, sleep bruxism had a significant but weak direct effect on daytime problematic behavior, while sleep bruxism significantly correlated with obstructive sleep apnea, which had a higher direct effect on daytime problematic behavior. CONCLUSIONS: Sleep bruxism was reported in 21.0% of Japanese children and had independent relationships with age, movements during sleep, and snoring. A comorbidity of sleep-disordered breathing might be related to daytime problematic behavior in children with sleep bruxism.
Assuntos
Transtornos do Comportamento Infantil/complicações , Síndromes da Apneia do Sono/complicações , Bruxismo do Sono/complicações , Fatores Etários , Criança , Pré-Escolar , HumanosRESUMO
Superconductivity in the cuprates is found to be intertwined with charge and spin density waves. Determining the interactions between the different types of order is crucial for understanding these important materials. Here, we elucidate the role of the charge density wave (CDW) in the prototypical cuprate La1.885Sr0.115CuO4, by studying the effects of large magnetic fields (H) up to 24 Tesla. At low temperatures (T), the observed CDW peaks reveal two distinct regions in the material: a majority phase with short-range CDW coexisting with superconductivity, and a minority phase with longer-range CDW coexisting with static spin density wave (SDW). With increasing magnetic field, the CDW first grows smoothly in a manner similar to the SDW. However, at high fields we discover a sudden increase in the CDW amplitude upon entering the vortex-liquid state. Our results signify strong coupling of the CDW to mobile superconducting vortices and link enhanced CDW amplitude with local superconducting pairing across the H - T phase diagram.
RESUMO
Reportedly, antiapoptotic Bcl-2 family proteins suppress apoptosis by binding to and inhibiting members of the CED-4 family of caspase activators. To explore this question, we used embryonic stem (ES) cells in which one (-/+) or both (-/-) copies of the gene encoding apoptotic protease activating factor 1 (Apaf-1), a CED-4 homologue, were disrupted by homologous recombination. Stable clones of heterozygous (-/+) and homozygous (-/-) Apaf-1 knockout ES cells that overexpressed Bcl-2 were generated. Withdrawal of serum growth factors or stimulation of heterozygous ES cells with staurosporine (STS), ultraviolet (UV)B irradiation, etoposide (VP16), or cisplatin induced apoptosis followed by cell death (determined by failure to exclude propidium iodide dye). These cell death stimuli also induced activation of several types of caspases and loss of mitochondrial membrane potential (DeltaPsi) in heterozygous (+/-) Apaf-1 knockout ES cells. In addition, overexpression of Bcl-2 protected against these events in Apaf-1-expressing ES cells. In contrast, STS, UVB, and VP16 induced little or no caspase activation and apoptosis in homozygous (-/-) Apaf-1 knockout ES cells. Nevertheless, Apaf-1-deficient ES cells subjected to these cell death stimuli or deprived of growth factors did eventually die through a nonapoptotic mechanism associated with loss of DeltaPsi. Moreover, Bcl-2 overprotection preserved DeltaPsi, reduced the percentage of Apaf-1(-/)- ES cells undergoing cell death, and increased clonigenic survival. The extent of Bcl-2-mediated cytoprotection was not significantly different for heterozygous (-/+) versus homozygous (-/-) Apaf-1 knockout cells. Furthermore, although Bcl-2 could be readily coimmunoprecipitated with Bax, associations with Apaf-1 were undetectable under conditions where Apaf-1 interactions with procaspase-9 were observed. We conclude that Bcl-2 has cytoprotective functions independent of Apaf-1, preserving mitochondrial function through a caspase-independent mechanism.
Assuntos
Apoptose/fisiologia , Proteínas/genética , Proteínas/fisiologia , Proteínas Proto-Oncogênicas c-bcl-2/fisiologia , Sequência de Aminoácidos , Animais , Antineoplásicos/farmacologia , Apoptose/genética , Apoptose/efeitos da radiação , Fator Apoptótico 1 Ativador de Proteases , Caspases/metabolismo , Morte Celular/genética , Morte Celular/fisiologia , Morte Celular/efeitos da radiação , Células Clonais , Ativação Enzimática , Expressão Gênica , Genes bcl-2 , Camundongos , Camundongos Knockout , Microscopia Eletrônica , Oligopeptídeos/química , Proteínas Proto-Oncogênicas/metabolismo , Proteínas Proto-Oncogênicas c-bcl-2/genética , Células-Tronco/citologia , Células-Tronco/fisiologia , Especificidade por Substrato , Raios Ultravioleta , Proteína X Associada a bcl-2RESUMO
Patients with advanced non-small cell lung cancer invading a chest wall are surgical candidates if complete resection is possible. When a primary tumor locating the lower lobe invades an inferior chest wall, either a wide skin incision or double skin incisions to secure surgical views both for dissection of hilum and mediastinum and for inferior chest wall resection is necessary. Wider incision causes higher rate of wound necrosis and infection. We describe a combined approach of thoracoscopic and open chest surgery for lobectomy and inferior chest wall resection, respectively. Patient was a 68-year-old man with an advanced non-small cell lung cancer. Video-assisted thoracoscopic middle and lower lobectomies and mediastinal nodal dissection was completed via 5 ports. Chest wall resection including the posterior portion of the 9th and 10th ribs and the transverse process followed inferior postero-lateral thoracotomy. Postoperative course was uneventful. The present surgical approach can avoid a wide thoracotomy for an advanced lung cancer invading an inferior chest wall.
Assuntos
Carcinoma Pulmonar de Células não Pequenas/cirurgia , Neoplasias Pulmonares/cirurgia , Pneumonectomia/métodos , Cirurgia Torácica Vídeoassistida/métodos , Parede Torácica/cirurgia , Toracotomia/métodos , Idoso , Carcinoma Pulmonar de Células não Pequenas/patologia , Terapia Combinada , Humanos , Neoplasias Pulmonares/patologia , Masculino , Invasividade Neoplásica , Estadiamento de Neoplasias , Neoplasias Torácicas/patologia , Neoplasias Torácicas/cirurgia , Resultado do TratamentoRESUMO
We report on the outcomes of flexor tendon repair in zone 2 subzones with early active mobilization in 102 fingers in 88 consecutive patients. There were 28, 53, 15, and six fingers with repairs in zones 2A to 2D, respectively. Rupture of the repair occurred in four fingers, all in zone 2B. Excluding those with repair ruptures, the mean total active motion was 230° (range 143°-286°). Evaluated with Tang's criteria, the outcomes were ranked excellent in 39 fingers, good in 46, fair in ten, poor in three, and failure in four. The outcomes in zone 2C were significantly inferior to those in zones 2B and 2D ( p = 0.02). Our results suggest that the tendon laceration in the area covered by the A2 pulley (zone 2C) is the most difficult area to obtain satisfactory active digital motion and tendon repair in zone 2B is the area where the risk of rupture is highest. LEVEL OF EVIDENCE: IV.
Assuntos
Traumatismos dos Dedos/reabilitação , Traumatismos dos Dedos/cirurgia , Traumatismos dos Tendões/reabilitação , Traumatismos dos Tendões/cirurgia , Adolescente , Adulto , Idoso , Idoso de 80 Anos ou mais , Criança , Terapia por Exercício , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Amplitude de Movimento Articular , Recuperação de Função Fisiológica , Estudos Retrospectivos , Técnicas de Sutura , Suturas , Resultado do Tratamento , Adulto JovemRESUMO
Charge density wave (CDW) correlations have been shown to universally exist in cuprate superconductors. However, their nature at high fields inferred from nuclear magnetic resonance is distinct from that measured with x-ray scattering at zero and low fields. We combined a pulsed magnet with an x-ray free-electron laser to characterize the CDW in YBa2Cu3O6.67 via x-ray scattering in fields of up to 28 tesla. While the zero-field CDW order, which develops at temperatures below ~150 kelvin, is essentially two dimensional, at lower temperature and beyond 15 tesla, another three-dimensionally ordered CDW emerges. The field-induced CDW appears around the zero-field superconducting transition temperature; in contrast, the incommensurate in-plane ordering vector is field-independent. This implies that the two forms of CDW and high-temperature superconductivity are intimately linked.
RESUMO
Thyrsiferyl 23-acetate (TF23A), a cytotoxic compound from marine red alga, has been shown to potently and specifically inhibit serine/threonine protein phosphatase 2A (PP2A) with IC50 values of 4-16 microM, depending on the enzyme concentration. TF23A did not affect activity of protein phosphatase 1 (PP1), 2B (PP2B), 2C (PP2C), or protein tyrosine phosphatases (PTP) up to 1 mM. It inhibited PP2A activity in a crude extract of a human T cell line, Jurkat cell, as well as the purified catalytic subunit. Thus, TF23A proved to be a novel useful probe for clearly distinguishing the activity of PP2A from those of the other protein phosphatases in crude cell extracts and identification of cellular processes that are regulated by PP2A.
Assuntos
Fosfoproteínas Fosfatases/antagonistas & inibidores , Piranos/farmacologia , Linhagem Celular , Éteres Cíclicos/farmacologia , Humanos , Cinética , Substâncias Macromoleculares , Estrutura Molecular , Ácido Okadáico , Fosfoproteínas Fosfatases/isolamento & purificação , Proteína Fosfatase 1 , Proteína Fosfatase 2 , Piranos/química , Rodófitas , Fluoreto de Sódio/farmacologia , Células Tumorais CultivadasRESUMO
Dot-immunobinding assays of IgE and CEA were performed by a conventional dot-ELISA technique with diaminobenzidine staining, and the quantitative results were compared by densitometry and a new, spectroscopic, optical beam deflection (OBD) method using the same membrane. It was possible with the OBD method to detect quantities of these substances at least ten times smaller than with densitometry. Better intra-assay reproducibility for IgE and CEA measurements was obtained by the OBD method. The measurable ranges of the OBD method was broader than that of densitometry, because dark bands caused OBD in proportion to their color densities. When the dot-immunobinding assay with OBD measurement for CEA was also compared with a microtube ELISA using biotin-avidin conjugates, the sensitivities and reproducibilities of the two methods were found to be similar, with a correlation coefficient of 0.991.
Assuntos
Antígeno Carcinoembrionário/análise , Ensaio de Imunoadsorção Enzimática/métodos , Immunoblotting/métodos , Imunoglobulina E/análise , Densitometria , Humanos , Técnicas In Vitro , Espectrofotometria/métodos , Coloração e RotulagemRESUMO
A microtiter latex antiglobulin test (LAGT) with heavy-and-stable latex particles was developed. Antibodies of weak avidity, such as rabbit antisera to DNP or digoxin were much enhanced by the LAGT, whereas the method only slightly promoted strong avidity antibody, such as that found in rabbit antisera to human chorionic gonadotrophin. A microtiter latex agglutination-inhibition test (LAGIT) proved to be an effective tool for detection of weak antigenic substances such as digoxin and DNP.
Assuntos
Anticorpos/análise , Antígenos/imunologia , Teste de Coombs , Dinitrofenóis , Animais , Gonadotropina Coriônica/imunologia , Digoxina/imunologia , Haptenos/imunologia , Humanos , Testes de Fixação do Látex/métodos , Coelhos , Soroalbumina Bovina/imunologiaRESUMO
Volumes of agglutinates produced by the microtiter latex antiglobulin test (LAGT) were measured by an electronic data processing (EDP) method using a particle volume distribution analyzer. This method proved highly sensitive for quantitating weak antibodies, such as anti-digoxin and anti-DNP. EDP measurement of the microtiter latex antiglobulin-inhibition test (LAGIT) is also a suitable method for quantitating HCG, digoxin and DNP.
Assuntos
Anticorpos/análise , Gonadotropina Coriônica/análise , Teste de Coombs , Digoxina/análise , Dinitrofenóis , Soroalbumina Bovina/análise , Animais , Gonadotropina Coriônica/imunologia , Digoxina/imunologia , Testes de Fixação do Látex/métodos , Microcomputadores , Coelhos , Soroalbumina Bovina/imunologiaRESUMO
The effects of tautomycin and its derivatives on protein phosphatases PP1 and PP2A and their apoptosis-inducing activity toward human leukemia Jurkat cells were examined, and the relationship between chemical structure and function was discussed. Among the compounds we examined, tautomycin was the most potent inhibitor and the most effective inducer of apoptosis. It inhibited PP1 and PP2A enzymatic activity concentration-dependently with IC50 values of 20 and 75 pM, respectively, in the presence of 0.01% Brij-35, and an LC50 value of 1 microM. Esterification of the anhydride moiety of tautomycin markedly increased the IC50 for the protein phosphatases. The C1'-C7' fragment of tautomycin had no inhibitory effect, but the fragment containing the C22-C26 moiety was inhibitory. These results suggest that the C22-C26 moiety is essential for inhibition of protein phosphatase activity and that the anhydride moiety enhances the inhibition. However, the esterification of the anhydride did not decrease, nor did the inclusion of the C22-C26 moiety increase the apoptosis-inducing activity. On the other hand, the C1-C18 moiety of tautomycin was essential for induction of apoptosis, and the conformation and the arrangement of functionalities of the C18-C26 carbon chain affected the apoptosis activity. However, modification of C1-C18, C1-C21, or C1-C26 compounds had little effect on phosphatase inhibitory activity. Our results strongly suggest that different moieties of tautomycin are involved in protein phosphatase inhibition and induction of apoptosis.
Assuntos
Apoptose/efeitos dos fármacos , Inibidores Enzimáticos/farmacologia , Isoenzimas/antagonistas & inibidores , Fosfoproteínas Fosfatases/antagonistas & inibidores , Piranos , Compostos de Espiro , Antifúngicos/síntese química , Antifúngicos/química , Antifúngicos/farmacologia , Catálise , DNA de Neoplasias/química , DNA de Neoplasias/efeitos dos fármacos , Detergentes/farmacologia , Humanos , Isoenzimas/química , Células Jurkat , Fosfoproteínas Fosfatases/química , Polidocanol , Polietilenoglicóis/farmacologia , Relação Estrutura-AtividadeRESUMO
Recent reports have described clinical benefits of all-trans-retinoic acid (ATRA) therapy for acute promyelocytic leukemia (APL). This paper describes severe hypercalcemia (serum calcium: 18.7 mg/dl) in association with ATRA treatment in a 14 year old girl with APL. Serum parathyroid hormone (PTH) concentrations were normal (0.21 ng/ml), which precludes the possibility of primary hyperparathyroidism or ectopic PTH secretion as a cause of the hypercalcemia. As for the factors which can accelerate mineral resorption, there were no apparent increases in the levels of PTH-related protein (PTH-rP), prostaglandins and vitamin D metabolites. In our in vitro experiment, ATRA did not stimulate the leukemic cells to produce PTH-rP. We speculate that ATRA, like PTH, may increase osteoclastic activity and induce hypercalcemia.
Assuntos
Hipercalcemia/induzido quimicamente , Leucemia Promielocítica Aguda/tratamento farmacológico , Tretinoína/efeitos adversos , Adolescente , Feminino , Humanos , Hipercalcemia/complicações , Leucemia Promielocítica Aguda/complicações , Proteína Relacionada ao Hormônio Paratireóideo , Proteínas/metabolismo , Tretinoína/uso terapêuticoRESUMO
New latex particles for immunologic agglutination reaction were prepared by a seeded polymerization technique for the emulsifier-free copolymerization of styrene and glycidyl methacrylate. The surface of the latex particles was presumed to be dotted with hydrophilic domains, giving stability to the particles. The remaining areas, to which many antigens or antibodies were strongly adsorbed, were hydrophobic. Various groups of the glycidyl methacrylate-styrene latex particles were coated with human immunoglobulin G, and immunologic agglutinating potencies were compared by the box-titration method. Immunologic reactivities of the latex particles decreased with an increase of glycidyl methacrylate content at concentrations of 1 mol% or higher. Latex particles containing 0.5 to 0.75 mol% GMA caused strong immunologic agglutination besides showing good stability, indicating the availability of these latex particles. Glycidyl methacrylate-free polystyrene latex particles caused non-specific agglutination, while the immunologic agglutinating ability of glycidyl methacrylate-styrene latex particles, prepared by the unseeded polymerization technique was weak.
Assuntos
Acrilatos , Compostos de Epóxi , Éteres Cíclicos , Testes de Fixação do Látex/instrumentação , Metacrilatos , Poliestirenos , AdsorçãoRESUMO
Activities of protein phosphatases PP1 and PP2A were determined in T and B lymphocytes of autoimmune-prone MRL/MpJ-lpr/lpr mice (MRL/lpr mice) and two control strains, MRL/MpJ-(+)/+ mice (MRL/+/+ mice) and C3H/HeJ mice. Potential PP1 activity, which was measured after treatment of cell extract with Co(2+)-trypsin, was much higher in T lymphocytes than B lymphocytes. However, no difference in the activity was observed between MRL/lpr mice and the controls. Spontaneous PP2A activity showed similar levels in T and B lymphocytes from normal mice, but potential PP2A activity, which was measured after treatment with 2-mercaptoethanol, was significantly higher in T lymphocytes from MRL/lpr mice than those from controls. No differences were detected in PP1 or PP2A activities in B lymphocytes. From these results, our previous data [Matsuzawa, S. et al. (1992) J. Biochem. 111, 472-477] demonstrating increases in potential activities of PP1 and PP2A in lymphoid tissues from autoimmune MRL/lpr mice can be interpreted as follows. 1) The increase in potential PP1 activity of the lymphoid tissues from MRL/lpr mice is caused by replacement of B lymphocytes by abnormal T lymphocytes, which accumulate in enormous numbers. 2) The increase of potential PP2A activity in the lymphoid tissues from MRL/lpr mice is caused by the increase in this activity in their T lymphocytes.
Assuntos
Doenças Autoimunes/enzimologia , Linfócitos B/enzimologia , Fosfoproteínas Fosfatases/metabolismo , Linfócitos T/enzimologia , Animais , Linfócitos B/efeitos dos fármacos , Éteres Cíclicos/farmacologia , Camundongos , Camundongos Endogâmicos C3H , Ácido Okadáico , Fosfoproteínas Fosfatases/antagonistas & inibidores , Proteínas/farmacologia , Linfócitos T/efeitos dos fármacosRESUMO
Activities of protein tyrosine kinase (PTK) and protein tyrosine phosphatase (PTP) in autoimmune MRL/MpJ-lpr/lpr mice (lpr mice) were measured and compared with the activities in the tissues from MRL/MpJ-+/+ mice (+/+ mice) as the control. In the spleen and liver, PTK activities in cytosol and membrane fractions were about 1.7- and 1.3-fold, respectively, higher in lpr mice than +/+ mice. PTP activities in cytosol and membrane fractions from lpr mice were 1.7- and 1.3-fold, respectively, higher in spleen, and 2.5- and 1.3-fold, respectively, higher in liver compared with those of the controls. These results demonstrate that the mutation of lpr gene resulted in elevation of PTK and PTP activities. Then, we measured the amounts and activities of SH-PTP1, a cytosolic PTP playing a crucial role in intracellular signaling from Fas antigen. The amounts of SH-PTP1 were about 4-fold larger in thymus, spleen, and lymphnodes than in liver, but there was no marked difference in the amounts between lpr and +/+ mice. On the other hand, activity of SH-PTP1 was definitely lower in lpr spleen and lymphnodes than +/+ spleen, but several times higher in lpr liver than +/+ liver. Tyrosine phosphorylation levels of SH-PTP1 in spleen of lpr and +/+ mice were similar. However, in liver, it was less phosphorylated in lpr than in +/+ mice. This hypophosphorylation might cause the activation of SH-PTP1 activity in lpr liver.
Assuntos
Doenças Autoimunes/enzimologia , Proteínas Tirosina Fosfatases/metabolismo , Animais , Membrana Celular/enzimologia , Citosol/enzimologia , Regulação para Baixo , Peptídeos e Proteínas de Sinalização Intracelular , Fígado/enzimologia , Camundongos , Proteína Tirosina Fosfatase não Receptora Tipo 11 , Proteína Tirosina Fosfatase não Receptora Tipo 6 , Transdução de Sinais , Baço/enzimologia , Regulação para Cima , Receptor fas/metabolismoRESUMO
The assay conditions for protein phosphatase 2B (PP2B) in crude extracts from mouse lymphoid tissues and lymphocytes were extensively investigated. Under the conditions elucidated, the PP2B activity was measured in autoimmune-prone MRL/MpJ-lpr/lpr mice (MRL/lpr mice) and two control strains, MRL/MpJ- +/+ mice (MRL/+/+ mice) and C3H/HeJ mice. In the control mice, PP2B activity was distinctly higher in spleen and thymus than brain and liver. PP2B activity was further elevated in spleen of MRL/lpr mice than in the controls. Furthermore, we observed a specific increase in PP2B activity in T lymphocytes from MRL/lpr mice as compared with in those from control mice. On the other hand, no alteration was observed in PP2B activity in B lymphocytes. These results suggest the involvement of PP2B in the abnormal signal transduction and proliferation of T lymphocytes in MRL/lpr mice.
Assuntos
Doenças Autoimunes/enzimologia , Tecido Linfoide/enzimologia , Fosfoproteínas Fosfatases/metabolismo , Linfócitos T/enzimologia , Animais , Encéfalo/enzimologia , Feminino , Fígado/enzimologia , Lúpus Eritematoso Sistêmico/enzimologia , Camundongos , Camundongos Endogâmicos C3H , Camundongos Endogâmicos , Fosfoproteínas Fosfatases/antagonistas & inibidores , Baço/enzimologia , Timo/enzimologiaRESUMO
The differential assay conditions for protein phosphatases PP1, PP2A, and PP2C were extensively studied by using crude extracts from mouse lymphoid tissues as enzyme sources. Under these conditions, the protein phosphatase activities were measured in MRL/MpJ-lpr/lpr mice (MRL/lpr mice), autoimmune-prone mice, and MRL/MpJ(-)+/+ mice (MRL/+/+ mice) and C3H/HeJ mice as the controls. In MRL/lpr mice, significant alterations in protein phosphatase activities from those in the control mice were demonstrated. In spleen and liver from MRL/lpr mice, potential activities of PP1 and PP2A were distinctly elevated over those of the control mice. These elevations appeared to be due to accumulation of the abnormal lymphocytes that emerged in MRL/lpr mice. Although the PP1 activity in MRL/lpr lymph nodes was lower than those of normal spleen and thymus, it was greatly increased by Co(2+)-trypsin treatment so that the PP1 activity of MRL/lpr lymph nodes was the highest among those of all the tissues examined. In contrast, PP2C activity showed no remarkable alteration in the autoimmune disease model mice as compared with that in the control mice. These results demonstrated a specific elevation in potency of protein dephosphorylation in the tissues of MRL/lpr mice, suggesting a new explanation for the defect in signal transduction in this disease.
Assuntos
Doenças Autoimunes/enzimologia , Autoimunidade/fisiologia , Isoenzimas/metabolismo , Tecido Linfoide/enzimologia , Fosfoproteínas Fosfatases/metabolismo , Animais , Doenças Autoimunes/genética , Autoimunidade/genética , Etanol/farmacologia , Éteres Cíclicos/farmacologia , Feminino , Isoenzimas/antagonistas & inibidores , Camundongos , Camundongos Endogâmicos , Ácido Okadáico , Concentração Osmolar , Fosfoproteínas Fosfatases/antagonistas & inibidores , Tripsina/farmacologiaRESUMO
In response to stimulation of B-cells through cell surface IgM, the activity of the serine/threonine protein phosphatase PP1, but not PP2A, was transiently decreased and reached a minimum 10-20 min after the stimulation. The decrease was more profound in the immature B-cell line WEHI-231, than in the mature B-cell line BAL-17. Under these conditions, PP1alpha, an isoform of PP1, showed unique alterations in the patterns of several spots with distinct isoelectic points in the Western blot after two-dimensional electrophoresis, whereas another isoform, PP1delta, did not show any alteration. PP1gamma1 and PP1gamma2 were not detected in B-cells. Similar alterations in these spots were observed in B-cells stimulated by PMA. When partially purified PP1 consisting of PP1alpha and PP1delta was incubated with [gamma-32P]ATP and PKC, radioactive spots of PP1alpha could be detected, but no spot of PP1delta was detected. Because differences in sequence among PP1 isoforms are mostly restricted to their C-terminals, phosphorylation rates of the C-terminal peptides containing the PKC-phosphorylation motif were compared. The C-terminal peptide of PP1alpha is a better substrate for PKC than those of PP1gamma1 and PP1gamma2, and is phosphorylated at the serine residue corresponding to Ser-325 of PP1alpha. The corresponding C-terminal region of PP1delta does not contain the phosphorylation site. On the other hand, there was a large difference in subcellular distribution of PP1delta, but not PP1alpha, between immature and mature B-cells. From these results, it was strongly suggested that PP1alpha is involved, via phosphorylation by PKC, in the regulation of signal transduction in response to the stimulation of B-cells through cell surface IgM.