Your browser doesn't support javascript.
loading
Mostrar: 20 | 50 | 100
Resultados 1 - 20 de 57
Filtrar
Mais filtros










Base de dados
Intervalo de ano de publicação
1.
Front Psychol ; 12: 558930, 2021.
Artigo em Inglês | MEDLINE | ID: mdl-33828498

RESUMO

Nation-wide community quarantines and social distancing are part of the new normal because of the global COVID-19 pandemic. Since extensive and prolonged lockdowns are relatively novel experiences, not much is known about the well-being of individuals in such extreme situations. This research effort investigated the relationship between well-being elements and resiliency of 533 Filipino adults who were placed under the nationwide enhanced community quarantine (ECQ) during the COVID-19 pandemic. Participants comprised of 376 females (70.56%) and 157 males (29.45%). The median and mode ages of the participants is 23 years, while 25 is the mean age. PERMA Profiler was used to measure participants' well-being elements, while Connor-Davidson Resiliency Scale-10 (CD-RISC-10) was used to measure their resiliency. Collected data were analyzed using the regression model and necessary condition analysis. This study corroborated that all the five pillars of well-being are significant positive correlates of resiliency (p < 0.00) in quarantined adults. The results shown accomplishment (ß = 0.447, p < 0.01) positively predicts resiliency, while negative emotions (ß = -0.171, p < 0.00) negatively predict resiliency. Lastly, the five pillars of well-being are necessary-but-not-sufficient conditions (ceiling envelopment with free disposal hull, CE-FDH p < 0.00) of resiliency. Our results cast a new light on well-being elements as constraints rather than enablers of resiliency. This novel result shows that optimum resiliency is only possible when all the five pillars of well-being are taken care of and when a person is at least minimally contented with their physical health. The present findings underscore the importance of a holistic as against an atomistic approach to maintaining good mental health, which suggests that deficiencies in certain areas of well-being may not be fully addressed by overcompensating on other areas, as all five pillars of well-being are necessary-but-not-sufficient conditions of resiliency. The study ends with the recommendation for the use of necessary condition analysis to study both classical and novel psychological research problems.

2.
J Endocrinol Invest ; 41(6): 711-717, 2018 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-29159607

RESUMO

BACKGROUND: Congenital hypothyroidism is a frequent disease occurring with an incidence of about 1/1500 newborns/year. In about 75% of the cases, CH is caused by alterations in thyroid morphogenesis, defined "thyroid dysgenesis" (TD). TD is generally a sporadic disease but in about 5% of the cases a genetic origin has been demonstrated. Previous studies indicate that Dnajc17 as a candidate modifier gene for hypothyroidism, since it is expressed in the thyroid bud, interacts with NKX2.1 and PAX8 and it has been associated to the hypothyroid phenotype in mice carrying a single Nkx2.1 and Pax8 genes (double heterozygous knock-out). PURPOSE: The work evaluates the possible involvement of DNAJC17 in the pathogenesis of TD. METHODS: High-resolution DNA melting analysis (HRM) and direct sequencing have been used to screen for mutations in the DNAJC17 coding sequence in 89 patients with TD. RESULTS: Two mutations have been identified in the coding sequence of DNAJC17 gene, one in exon 5 (c.350A>C; rs79709714) and one in exon 9 (c.610G>C; rs117485355). The last one is a rare variant, while the rs79709714 is a polymorphism. Both are present in databases and the frequency of the alleles is not different between TD patients and controls. CONCLUSIONS: DNAJC17 mutations are not frequently present in patients with TD.


Assuntos
Biomarcadores/análise , Proteínas de Choque Térmico HSP40/genética , Mutação , Fator de Transcrição PAX8/genética , Reação em Cadeia da Polimerase em Tempo Real/métodos , Disgenesia da Tireoide/genética , Fator Nuclear 1 de Tireoide/genética , Criança , Análise Mutacional de DNA , Feminino , Humanos , Fenótipo , Prognóstico , Disgenesia da Tireoide/diagnóstico
3.
Neuroscience ; 123(4): 931-8, 2004.
Artigo em Inglês | MEDLINE | ID: mdl-14751286

RESUMO

The gene for TFII-I, a widely expressed transcription factor, has been localized to an interval of human chromosome 7q11.23 that is commonly deleted in Williams syndrome (WS). The clinical phenotype of WS includes elfin facies, infantile hypercalcemia, supravalvular aortic stenosis, hyperacusis and mental retardation. The WS cognitive profile (WSCP) is notable for the differential impairment of visual-spatial abilities with relative sparing of verbal-linguistic function. Fine mapping of individuals with WS has revealed a close association between deletion of TFII-I and the WSCP. To determine the plausibility of the hypothesis that hemizygous deletion of TFII-I contributes to the WSCP, we have examined the anatomic distribution of TFII-I RNA and protein isoforms in brains from adult and embryonic mice. Our studies show that early in development, TFII-I expression is widespread and nearly uniform throughout the brain. In adult brain, TFII-I protein is present exclusively in neurons. Highest levels of expression are observed in cerebellar Purkinje cells and in hippocampal interneurons. TFII-I immunoreactivity is distinct from that of the related protein, TFII-IRD1, which is also localized to the region of human chromosome 7 deleted in WS. The expression pattern of TFII-I in mouse brain parallels regions in human brain which have been shown to be anatomically and functionally altered in humans with WS. These observations are consistent with the hypothesis that deletion of the gene for TFII-I contributes to the cognitive impairments observed in WS.


Assuntos
Encéfalo/metabolismo , Expressão Gênica , Fenótipo , Fatores de Transcrição TFII/genética , Síndrome de Williams/genética , Animais , Encéfalo/citologia , Encéfalo/crescimento & desenvolvimento , Linhagem Celular , Embrião de Mamíferos , Éxons/fisiologia , Humanos , Immunoblotting/métodos , Imuno-Histoquímica/métodos , Hibridização In Situ/métodos , Rim , Camundongos , Camundongos Endogâmicos C57BL , Neurônios/metabolismo , Peptídeos/imunologia , Isoformas de Proteínas/imunologia , Isoformas de Proteínas/metabolismo , RNA Mensageiro/metabolismo , Fatores de Transcrição TFII/metabolismo , Síndrome de Williams/metabolismo
4.
Mol Cell Biol ; 21(12): 3935-46, 2001 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-11359901

RESUMO

Some patients with B-cell-negative severe combined immune deficiency (SCID) carry mutations in RAG-1 or RAG-2 that impair V(D)J recombination. Two recessive RAG-1 mutations responsible for B-cell-negative SCID, R621H and E719K, impair V(D)J recombination without affecting formation of single-site recombination signal sequence complexes, specific DNA contacts, or perturbation of DNA structure at the heptamer-coding junction. The E719K mutation impairs DNA cleavage by the RAG complex, with a greater effect on nicking than on transesterification; a conservative glutamine substitution exhibits a similar effect. When cysteine is substituted for E719, RAG-1 activity is enhanced in Mn(2+) but remains impaired in Mg(2+), suggesting an interaction between this residue and an essential metal ion. The R621H mutation partially impairs nicking, with little effect on transesterification. The residual nicking activity of the R621H mutant is reduced at least 10-fold upon a change from pH 7.0 to pH 8.4. Site-specific nicking is severely impaired by an alanine substitution at R621 but is spared by substitution with lysine. These observations are consistent with involvement of a positively charged residue at position 621 in the nicking step of the RAG-mediated cleavage reaction. Our data provide a mechanistic explanation for one form of hereditary SCID. Moreover, while RAG-1 is directly involved in catalysis of both nicking and transesterification, our observations indicate that these two steps have distinct catalytic requirements.


Assuntos
Rearranjo Gênico do Linfócito B , Proteínas de Homeodomínio/genética , Mutação , Recombinação Genética , Imunodeficiência Combinada Severa/genética , Imunodeficiência Combinada Severa/imunologia , Linfócitos B/imunologia , Sequência de Bases , Cátions Bivalentes , Linhagem Celular , DNA/metabolismo , Primers do DNA/genética , Esterificação , Humanos
5.
J Biol Chem ; 276(30): 27806-15, 2001 Jul 27.
Artigo em Inglês | MEDLINE | ID: mdl-11373296

RESUMO

Bruton's tyrosine kinase (Btk), a member of the Tec family of cytosolic kinases, is essential for B cell development and function. BAP/TFII-I, a protein implicated in transcriptional regulation, is associated with Btk in B cells and is transiently phosphorylated on tyrosine following B cell receptor engagement. BAP/TFII-I is a substrate for Btk in vitro and is hyperphosphorylated on tyrosine upon coexpression with Btk in mammalian cells. In an effort to understand the physiologic consequences of BAP/TFII-I tyrosine phosphorylation following B cell receptor stimulation, site-directed mutagenesis and phosphopeptide mapping were used to locate the predominant sites of BAP/TFII-I phosphorylation by Btk in vitro. These residues, Tyr248, Tyr357, and Tyr462, were also found to be the major sites for Btk-dependent phosphorylation of BAP/TFII-I in vivo. Residues Tyr357 and Tyr462 are contained within the loop regions of adjacent helix-loop-helix-like repeats within BAP/TFII-I. Mutation of either Tyr248, Tyr357, or Tyr462 to phenylalanine reduced transcription from a c-fos promoter relative to wild-type BAP/TFII-I in transfected COS-7 cells, consistent with the interpretation that phosphorylation at these sites contributes to transcriptional activation. Phosphorylation of BAP/TFII-I by Btk may link engagement of receptors such as surface immunoglobulin to modulation of gene expression.


Assuntos
Proteínas de Ligação a DNA/química , Proteínas de Ligação a DNA/metabolismo , Proteínas Tirosina Quinases/química , Proteínas Tirosina Quinases/metabolismo , Fatores de Transcrição/química , Fatores de Transcrição/metabolismo , Tirosina Quinase da Agamaglobulinemia , Sequência de Aminoácidos , Animais , Linfócitos B/metabolismo , Sítios de Ligação , Células COS , Linhagem Celular , Relação Dose-Resposta a Droga , Epitopos/química , Escherichia coli/metabolismo , Genes Reporter , Humanos , Camundongos , Dados de Sequência Molecular , Mutação , Fenilalanina/química , Fosforilação , Plasmídeos/metabolismo , Mutação Puntual , Testes de Precipitina , Estrutura Terciária de Proteína , Proteínas Proto-Oncogênicas c-fos/metabolismo , Proteínas Recombinantes/metabolismo , Transcrição Gênica , Ativação Transcricional , Transfecção , Tripsina/metabolismo , Tirosina/química
6.
J Biol Chem ; 276(28): 26421-9, 2001 Jul 13.
Artigo em Inglês | MEDLINE | ID: mdl-11319221

RESUMO

The transcriptional activity of natural promoters is sensitive to the precise spatial arrangement of DNA elements and their incorporation into higher order DNA-protein complexes. STAT3 and c-Jun form a specific ternary complex in vitro with a synthetic DNA element containing AP1 and SIE sites. These associations are critical for synergistic activation of transcription from a synthetic promoter by STAT3 and c-Jun. Expression of the acute phase protein alpha(2)-macroglobulin is induced in vivo by interleukin-6 (IL-6)-related cytokines; we demonstrate that coordinate interactions among STAT3, c-Jun, and a specific array of DNA elements contribute to activation of the alpha(2)-macroglobulin promoter in response to IL-6 family members. At least five promoter elements are involved in activation: two AP1 sites at -113 to -107 and -152 to -140, an acute phase response element (APRE (SIE)) at -171 to -163, and two AT-rich regions at -143 to -138 and -128 to -123. Synergism between STAT3 or STAT3-C and c-Jun is impaired by mutation of the APRE (SIE) or either AP1 site, as well as by mutations that alter the AT-rich regions or their phasing. Mutations of STAT3 previously shown to disrupt physical and functional interactions with c-Jun do not impair synergy between STAT3-C and c-Jun at the alpha(2)-macroglobulin promoter in HepG2 cells, suggesting that STAT3-C and STAT3 differ with respect to their precise contacts with c-Jun.


Assuntos
Proteínas de Ligação a DNA/genética , DNA/genética , Proteínas Proto-Oncogênicas c-jun/genética , Transdução de Sinais/genética , Transativadores/genética , Sequência de Bases , Linhagem Celular , DNA/metabolismo , Proteínas de Ligação a DNA/metabolismo , Humanos , Dados de Sequência Molecular , Mutação , Regiões Promotoras Genéticas , Proteínas Proto-Oncogênicas c-jun/metabolismo , Fator de Transcrição STAT3 , Transativadores/metabolismo , Ativação Transcricional
7.
Mol Cell Biol ; 20(4): 1227-33, 2000 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-10648608

RESUMO

The B-cell lymphocyte kinase (Blk) is a src-family protein tyrosine kinase specifically expressed in B-lineage cells of mice. The early onset of Blk expression during B-cell development in the bone marrow and the high expression levels of Blk in mature B cells suggest a possible important role of Blk in B-cell physiology. To study the in vivo function of Blk, mice homozygous for the targeted disruption of the blk gene were generated. In homozygous mutant mice, neither blk mRNA nor Blk protein is expressed. Despite the absence of Blk, the development, in vitro activation, and humoral immune responses of B cells to T-cell-dependent and -independent antigens are unaltered. These data are consistent with functional redundancy of Blk in B-cell development and immune responses.


Assuntos
Linfócitos B/enzimologia , Linfócitos B/imunologia , Quinases da Família src/fisiologia , Animais , Formação de Anticorpos , Antígenos T-Independentes , Linfócitos B/citologia , Sequência de Bases , Diferenciação Celular , Primers do DNA/genética , Feminino , Marcação de Genes , Técnicas In Vitro , Ativação Linfocitária , Masculino , Camundongos , Camundongos Knockout , Fosforilação , RNA Mensageiro/genética , RNA Mensageiro/metabolismo , Linfócitos T/citologia , Linfócitos T/enzimologia , Linfócitos T/imunologia , Quinases da Família src/genética
10.
Mol Cell Biol ; 19(5): 3674-83, 1999 May.
Artigo em Inglês | MEDLINE | ID: mdl-10207091

RESUMO

V(D)J recombination occurs at recombination signal sequences (RSSs) containing conserved heptamer and nonamer elements. RAG-1 and RAG-2 initiate recombination by cleaving DNA between heptamers and antigen receptor coding segments. RAG-1 alone contacts the nonamer but interacts weakly, if at all, with the heptamer. RAG-2 by itself has no DNA-binding activity but promotes heptamer occupancy in the presence of RAG-1; how RAG-2 collaborates with RAG-1 has been poorly understood. Here we examine the composition of RAG-RSS complexes and the relative contributions of RAG-1 and RAG-2 to heptamer binding. RAG-1 exists as a dimer in complexes with an isolated RSS bearing a 12-bp spacer, regardless of whether RAG-2 is present; only a single subunit of RAG-1, however, participates in nonamer binding. In contrast, multimeric RAG-2 is not detectable by electrophoretic mobility shift assays in complexes containing both RAG proteins. DNA-protein photo-cross-linking demonstrates that heptamer contacts, while enhanced by RAG-2, are mediated primarily by RAG-1. RAG-2 cross-linking, while less efficient than that of RAG-1, is detectable near the heptamer-coding junction. These observations provide evidence that RAG-2 alters the conformation or orientation of RAG-1, thereby stabilizing interactions of RAG-1 with the heptamer, and suggest that both proteins interact with the RSS near the site of cleavage.


Assuntos
Proteínas de Ligação a DNA/genética , Genes de Imunoglobulinas/genética , Proteínas de Homeodomínio/genética , Sequência de Bases , Proteínas de Transporte/genética , Linhagem Celular , Proteínas de Ligação a DNA/análise , Proteínas de Ligação a DNA/metabolismo , Proteínas de Homeodomínio/metabolismo , Humanos , Proteínas Ligantes de Maltose , Dados de Sequência Molecular , Proteínas Nucleares , Oligodesoxirribonucleotídeos/genética , Oligodesoxirribonucleotídeos/metabolismo , Conformação Proteica , Proteínas Recombinantes de Fusão/genética , Recombinação Genética/genética
11.
Immunity ; 11(6): 771-81, 1999 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-10626899

RESUMO

Accumulation of the V(D)J recombinase protein RAG-2 is restricted to G0/G1 cells by phosphorylation-mediated degradation at the G1-S boundary. Here cyclin A/CDK2 is shown to oppose RAG-2 accumulation; conversely, RAG-2 is induced by p27Kip1 and related CDK inhibitors. Coinduction of RAG-2 and G1 delay by p27Kip1 is accompanied by strong stimulation of V(D)J recombination. Unexpectedly, induction of RAG-2 accumulation in the absence of G1 delay has no effect on recombination frequency. p27Kip1 may stimulate V(D)J recombination by coordinating accumulation of RAG-2 with prolongation of G1, when nonhomologous end joining is preferentially active. Consistent with this, enforced expression of RAG-2 throughout cell cycle is associated with accumulation of aberrant recombination products reminiscent of those formed in the absence of nonhomologous end joining.


Assuntos
Quinases relacionadas a CDC2 e CDC28 , Ciclina A/metabolismo , Quinases Ciclina-Dependentes/metabolismo , Reparo do DNA , Proteínas de Ligação a DNA/genética , Proteínas Serina-Treonina Quinases/metabolismo , Recombinação Genética , Animais , Ciclo Celular , Linhagem Celular Transformada , Quinase 2 Dependente de Ciclina , Inibidor de Quinase Dependente de Ciclina p21 , Ciclinas/genética , Ciclinas/metabolismo , DNA Nucleotidiltransferases , Proteínas de Ligação a DNA/metabolismo , Inibidores Enzimáticos/metabolismo , Humanos , Camundongos , Camundongos Knockout , Camundongos Transgênicos , Proteínas Nucleares , VDJ Recombinases
12.
Immunity ; 9(1): 115-25, 1998 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-9697841

RESUMO

Protein interactions with V(D)J recombination signal sequences (RSSs) were mapped in complexes containing RAG1 with (M1/2) or without (M1) RAG2. In both complexes, RAG interactions with the DNA backbone are biased toward one side of the helix; nonamer contacts resemble those of Hin with hixL. In the M1 complex, DNA contacts are centered on the nonamer. In the M1/2 complex, protein-RSS interactions extend through the spacer and into the nonamer-proximal portion of the heptamer. Chemical modifications near the heptamer-coding junction are overrepresented in the M1/2 complex, providing evidence for perturbation of DNA structure in this region. Thus, while RAG1 alone can bind the nonamer, RAG2 is required for heptamer occupancy.


Assuntos
Proteínas de Ligação a DNA/metabolismo , Genes de Imunoglobulinas , Proteínas de Homeodomínio/metabolismo , Região de Junção de Imunoglobulinas/genética , Região Variável de Imunoglobulina/genética , Recombinação Genética , Sequência de Bases , Linhagem Celular Transformada , DNA/metabolismo , Proteínas de Ligação a DNA/genética , Proteínas de Homeodomínio/genética , Humanos , Dados de Sequência Molecular , Mutagênese , Proteínas Nucleares , Oligodesoxirribonucleotídeos , Proteínas Recombinantes de Fusão/genética , Proteínas Recombinantes de Fusão/metabolismo
13.
Proc Natl Acad Sci U S A ; 95(13): 7351-6, 1998 Jun 23.
Artigo em Inglês | MEDLINE | ID: mdl-9636152

RESUMO

The intracellular signals governing cellular proliferation and developmental progression during lymphocyte development are incompletely understood. The tyrosine kinase Blk is expressed preferentially in the B lineage, but its function in B cell development has been largely unexplored. We have generated transgenic mice expressing constitutively active Blk [Blk(Y495F)] in the B and T lymphoid compartments. Expression of Blk(Y495F) in the B lineage at levels similar to that of endogenous Blk induced B lymphoid tumors of limited clonality, whose phenotypes are characteristic of B cell progenitors at the proB/preB-I to preB-II transition. Expression of constitutively active Blk in the T lineage resulted in the appearance of clonal, thymic lymphomas composed of intermediate single positive cells. Taken together, these results indicate that specific B and T cell progenitor subsets are preferentially susceptible to transformation by Blk(Y495F) and suggest a role for Blk in the control of proliferation during B cell development.


Assuntos
Transformação Celular Neoplásica , Células-Tronco Hematopoéticas/enzimologia , Quinases da Família src/metabolismo , Animais , Linfócitos B/citologia , Divisão Celular , Células Clonais , Ativação Enzimática , Expressão Gênica , Rearranjo Gênico , Camundongos , Camundongos Nus , Camundongos Transgênicos , Fosforilação , Linfócitos T/citologia , Transgenes , Tirosina/metabolismo , Quinases da Família src/genética
14.
Mol Cell Biol ; 17(12): 6932-9, 1997 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-9372925

RESUMO

V(D)J recombination is initiated by RAG-1 and RAG-2, which introduce double-strand DNA breaks at recombination signal sequences (RSSs) of antigen receptor gene segments to produce signal ends, terminating in blunt, double-strand breaks, and coding ends, terminating in DNA hairpins. While the formation of RAG-RSS complexes has been documented, observations regarding the individual contributions of RAG-1 and RAG-2 to RSS recognition are in conflict. Here we describe an assay for formation and maintenance of functional RAG-RSS complexes in the course of the DNA cleavage reaction. Under conditions of in vitro cleavage, the RAG proteins sequester intact substrate DNA in a stable complex which is formed prior to strand scission. The cleavage reaction subsequently proceeds through nicking and hairpin formation without dissociation of substrate. Notably, the presence of both RAG-1 and RAG-2 is essential for formation of stable, functional complexes with substrate DNA under conditions of the sequestration assay. Two classes of substrate mutation are distinguished by their effects on RAG-mediated DNA cleavage in vitro. A mutation of the first class, residing within the RSS nonamer and associated with coordinate impairment of nicking and hairpin formation, greatly reduces the stability of RAG association with intact substrate DNA. In contrast, a mutation of the second class, lying within the RSS heptamer and associated with selective abolition of hairpin formation, has little or no effect on the half-life of the RAG-substrate complex.


Assuntos
Proteínas de Ligação a DNA/genética , Proteínas de Ligação a DNA/metabolismo , Proteínas de Homeodomínio , Receptores de Antígenos de Linfócitos B/genética , Receptores de Antígenos de Linfócitos T/genética , DNA/química , DNA/genética , DNA/metabolismo , Humanos , Técnicas In Vitro , Cinética , Mutação , Proteínas Nucleares , Conformação de Ácido Nucleico , Recombinação Genética
15.
Curr Opin Immunol ; 9(4): 534-40, 1997 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-9287186

RESUMO

Bruton's tyrosine kinase (Btk), the target of inactivating mutations in X-linked immunodeficiency diseases of mice and humans, is essential for normal B cell responsiveness. Recent studies have outlined a mechanism for the activation of Btk by B cell receptor engagement and have identified proximal and distal targets of Btk action.


Assuntos
Linfócitos B/citologia , Síndromes de Imunodeficiência/enzimologia , Proteínas Tirosina Quinases/fisiologia , Transdução de Sinais/fisiologia , Tirosina Quinase da Agamaglobulinemia , Animais , Antígenos T-Independentes/imunologia , Linfócitos B/enzimologia , Diferenciação Celular , Ativação Enzimática , Humanos , Síndromes de Imunodeficiência/genética , Síndromes de Imunodeficiência/imunologia , Camundongos , Camundongos Mutantes , Fosforilação , Processamento de Proteína Pós-Traducional , Cromossomo X/genética , Quinases da Família src/fisiologia
16.
J Exp Med ; 186(2): 259-67, 1997 Jul 21.
Artigo em Inglês | MEDLINE | ID: mdl-9221755

RESUMO

The stimulatory and inhibitory pathways initiated by engagement of stimulatory receptors such as the B cell receptor for antigen (BCR) and inhibitory receptors such as Fcgamma receptors of the IIB1 type (FcgammaRIIB1) intersect in ways that are poorly understood at the molecular level. Because the tyrosine kinase Csk is a potential negative regulator of lymphocyte activation, we examined the effects of BCR and FcgammaRIIB1 engagement on the binding of Csk to phosphotyrosine-containing proteins. Stimulation of a B lymphoma cell line, A20, with intact anti-IgG antibody induced a direct, SH2-mediated association between Csk and a 62-kD phosphotyrosine-containing protein that was identified as RasGTPase-activating protein-associated p62 (GAP-A.p62). In contrast, stimulation of A20 cells with anti-IgG F(ab')2 resulted in little increase in the association of Csk with GAP-A.p62. The effect of FcgammaRIIB1 engagement on this association was abolished by blockade of FcgammaRIIB1 with the monoclonal antibody 2.4G2. Furthermore, the increased association between Csk and GAP-A.p62 seen upon stimulation with intact anti-Ig was abrogated in the FcgammaRIIB1-deficient cell line IIA1.6 and recovered when FcgammaRIIB1 expression was restored by transfection. The differential effects of BCR and BCR-FcgammaRIIB1-mediated signaling on the phosphorylation of GAP-A.p62 and its association with Csk suggest that docking of Csk to GAP-A.p62 may function in the negative regulation of antigen receptor-mediated signals in B cells.


Assuntos
Proteínas de Ligação a DNA/metabolismo , Fosfoproteínas/metabolismo , Proteínas Tirosina Quinases/metabolismo , Proteínas de Ligação a RNA/metabolismo , Receptores de Antígenos de Linfócitos B/fisiologia , Receptores de IgG/fisiologia , Sítios de Ligação , Proteína Tirosina Quinase CSK , Linhagem Celular , Humanos , Fosforilação , Domínios de Homologia de src , Quinases da Família src
17.
J Biol Chem ; 272(15): 10160-8, 1997 Apr 11.
Artigo em Inglês | MEDLINE | ID: mdl-9092562

RESUMO

The transcription factor Pax-5 is expressed during the early stages of B-cell differentiation and influences the expression of several B-cell-specific genes. In addition to the existing isoform (Pax-5, which we have named Pax-5a), we have isolated three new isoforms, Pax-5b, Pax-5d, and Pax-5e, from murine spleen and B-lymphoid cell lines using library screenings and polymerase chain reaction amplification. Isoforms Pax-5b and Pax-5e have spliced out their second exon, resulting in proteins with only a partial DNA-binding domain. Isoforms Pax-5d and Pax-5e have deleted the 3'-region, which encodes the transactivating domain, and replaced it with a novel sequence. The existence of alternative Pax-5 transcripts was confirmed using RNase protection assays. Furthermore, Pax-5a and Pax-5b proteins were detected using Western blot analysis. Pax-5a was detectable in pro-, pre-, and mature B-cell lines, but not in two plasmacytomas; Pax-5b was shown to be present at low levels in mature B-cell lines and, unexpectedly, in one plasma cell line, but not in pro-B-cell or T-cell lines. Mobility shift assays showed that in vitro translated Pax-5a and Pax-5d, but not Pax-5b or Pax-5e, could interact with a B-cell-specific activator protein-binding site on the blk promoter. Using this assay, we also showed that Pax-5d was present in nuclear extracts of some (but not all) B-lymphoid lines and interacts with the B-cell-specific activator protein-binding site. The pattern of differential expression of alternatively spliced Pax-5 isoforms suggests that they may be important regulators of transcription during B-cell maturation.


Assuntos
Processamento Alternativo , Linfócitos B/citologia , Proteínas de Ligação a DNA/genética , Proteínas Nucleares/genética , Fatores de Transcrição/genética , Sequência de Aminoácidos , Animais , Sequência de Bases , Western Blotting , Diferenciação Celular , DNA Complementar/química , Proteínas de Ligação a DNA/metabolismo , Humanos , Dados de Sequência Molecular , Proteínas Nucleares/metabolismo , Fator de Transcrição PAX5 , Reação em Cadeia da Polimerase , RNA Mensageiro/metabolismo , Coelhos , Ribonucleases/metabolismo , Fatores de Transcrição/metabolismo
18.
Proc Natl Acad Sci U S A ; 94(2): 604-9, 1997 Jan 21.
Artigo em Inglês | MEDLINE | ID: mdl-9012831

RESUMO

Bruton's tyrosine kinase (Btk) is essential for B cell activation, but downstream targets of Btk have not been defined. We now describe a protein, BAP-135, that is associated with Btk in B cells and is a substrate for phosphorylation by Btk. BAP-135, which exhibits no detectable homology to known proteins, contains six occurrences of a hitherto undescribed amino acid repeat and two motifs, similar to the Src autophosphorylation site, that represent potential targets for tyrosine phosphorylation. The pleckstrin homology domain of Btk comprises the principal site of BAP-135 binding. Btk-dependent phosphorylation of BAP-135 is abolished by mutations that impair activation of Btk by Src-related kinases. Btk and BAP-135 exist in a complex before B cell antigen receptor (BCR) engagement; in response to BCR crosslinking, BAP-135 is transiently phosphorylated on tyrosine. Taken together, these observations suggest that BAP-135 may reside downstream of Btk in a signaling pathway originating at the BCR.


Assuntos
Linfócitos B/fisiologia , Fosfoproteínas/metabolismo , Receptores de Antígenos de Linfócitos B/fisiologia , Fatores de Transcrição TFII , Tirosina Quinase da Agamaglobulinemia , Sequência de Aminoácidos , Sequência de Bases , Linhagem Celular , Clonagem Molecular , Sequência Consenso , Humanos , Ativação Linfocitária , Dados de Sequência Molecular , Fosfoproteínas/genética , Fosfotirosina/metabolismo , Ligação Proteica , Proteínas Tirosina Quinases/metabolismo , Sequências Repetitivas de Ácido Nucleico , Alinhamento de Sequência , Transdução de Sinais
19.
Immunity ; 5(6): 575-89, 1996 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-8986717

RESUMO

The proteins RAG-1 and RAG-2 are essential for initiation of V(D)J recombination. In dividing cells, RAG-2 accumulates during G1 and is undetectable during the S and G2/M cell cycle phases. A conserved degradation signal, including an essential CDK phosphorylation site at Thr-490, regulates RAG-2 accumulation during cell division and links V(D)J recombination to the cell cycle. Mutations within this signal abolish periodic degradation of RAG-2 protein in dividing cells. In mice expressing endogenous or wild-type transgenic RAG-2, V(D)J recombination intermediates accumulate preferentially in G0/G1 thymocytes; this restriction is relieved by mutation of Thr-490 to alanine (T490A). Thus, periodic destruction of RAG-2 protein couples V(D)J recombination to cell cycle phase. Using transgenic mice expressing the T490A RAG-2 mutant and a functional T cell receptor beta chain, we demonstrate that coupling of V(D)J recombination to the cell cycle is not essential for enforcement of allelic exclusion.


Assuntos
Ciclo Celular/fisiologia , Proteínas de Ligação a DNA , Genes de Imunoglobulinas , Fragmentos de Imunoglobulinas/genética , Proteínas/metabolismo , Recombinação Genética , Sequência de Aminoácidos , Animais , Quinases Ciclina-Dependentes/metabolismo , Feminino , Meia-Vida , Humanos , Região de Junção de Imunoglobulinas/genética , Região Variável de Imunoglobulina/genética , Camundongos , Camundongos Transgênicos , Dados de Sequência Molecular , Mutação , Proteínas Nucleares , Peptídeos/metabolismo , Periodicidade , Fosforilação , Receptores de Antígenos de Linfócitos T , Relação Estrutura-Atividade , Timo/citologia , Timo/metabolismo
20.
Science ; 274(5284): 97-9, 1996 Oct 04.
Artigo em Inglês | MEDLINE | ID: mdl-8810255

RESUMO

Patients with human severe combined immunodeficiency (SCID) can be divided into those with B lymphocytes (B+ SCID) and those without (B- SCID). Although several genetic causes are known for B+ SCID, the etiology of B- SCID has not been defined. Six of 14 B- SCID patients tested were found to carry a mutation of the recombinase activating gene 1 (RAG-1), RAG-2, or both. This mutation resulted in a functional inability to form antigen receptors through genetic recombination and links a defect in one of the site-specific recombination systems to a human disease.


Assuntos
Proteínas de Ligação a DNA , Proteínas de Homeodomínio , Proteínas/genética , Imunodeficiência Combinada Severa/genética , Linfócitos B/imunologia , Linhagem Celular , Consanguinidade , Feminino , Genes de Imunoglobulinas , Genes Recessivos , Humanos , Imunofenotipagem , Masculino , Mutação , Proteínas Nucleares , Polimorfismo Conformacional de Fita Simples , Receptores de Antígenos de Linfócitos T/genética , Recombinação Genética , Deleção de Sequência , Imunodeficiência Combinada Severa/imunologia , Transfecção
SELEÇÃO DE REFERÊNCIAS
DETALHE DA PESQUISA
...