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We investigated the association of clinical variables with TBS at baseline in the bone health sub-cohort of the VITamin D and OmegA-3 TriaL (VITAL). Lower TBS was associated with female sex, aging, BMI ≥ 25 kg/m2, SSRI use, high alcohol intake, and presence of diabetes; there was a trend towards significance between lower TBS and history of fragility fractures. INTRODUCTION: We investigated whether TBS differs by sex, race, body mass index (BMI), and other clinical variables. METHODS: The VITamin D and OmegA-3 TriaL (VITAL) is determining effects of vitamin D3 and/or omega-3 fatty acid (FA) supplements in reducing risks of cancer and cardiovascular disease. In the VITAL: Effects on Bone Structure/Architecture ancillary study, effects of these interventions on bone will be investigated. Here, we examine the associations of clinical risk factors with TBS assessments at baseline in the bone health sub-cohort, comprised of 672 participants (369 men and 303 women), mean (± SD) age 63.5 ± 6.0 years; BMI ≤ 37 kg/m2, no bisphosphonates within 2 years or other bone active medications within 1 year. RESULTS: TBS was greater in men than women (1.311 vs. 1.278, P < 0.001) and lower with elevated BMIs (P < 0.001), higher age (P = 0.004), diabetes (P = 0.008), SSRI use (P = 0.044), and high alcohol intake (P = 0.009). There was a trend for history of fragility fractures (P = 0.072), and lower TBS. TBS did not vary when analyzed by race, smoking, history of falls, and multivitamin or caffeine use. CONCLUSIONS: Lower TBS was associated with female sex, aging, BMI ≥ 25 kg/m2, SSRI use, alcohol use, and presence of diabetes; there was a trend between lower TBS and history of fragility fractures. TBS may be useful clinically to assess structural changes that may be associated with fractures among patients who are overweight or obese, those on SSRIs, or with diabetes. Ongoing follow-up studies will clarify the effects of supplemental vitamin D3 and/or FA's on TBS and other bone health measures. TRIAL REGISTRATION: NCT01747447.
Assuntos
Densidade Óssea/efeitos dos fármacos , Osso Esponjoso/efeitos dos fármacos , Colecalciferol/farmacologia , Suplementos Nutricionais , Ácidos Graxos Ômega-3/farmacologia , Absorciometria de Fóton/métodos , Idoso , Idoso de 80 Anos ou mais , Envelhecimento/fisiologia , Densidade Óssea/fisiologia , Osso Esponjoso/fisiopatologia , Método Duplo-Cego , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Inibidores Seletivos de Recaptação de Serotonina/farmacologia , Fatores SexuaisRESUMO
BACKGROUND: In the present study, we retrospectively evaluated the use of tomographic imaging in adult cancer patients to clarify how recent growth plateaus in the use of tomographic imaging in the United States might have affected oncologic imaging during the same period. METHODS: At a U.S. academic cancer centre, 12,059 patients with dates of death from January 2000 through December 2014 were identified. Imaging was restricted to brain and body computed tomography (ct), brain and body magnetic resonance (mr), and body positron-emission tomography (pet) with and without superimposed ct. Trends during the staging (1 year after diagnosis), monitoring (18-6 months before death), and end-of-life (final 6 months before death) phases were analyzed. RESULTS: Comparing the 2005-2009 with the 2010-2014 period, mean intensity of pet imaging increased 21% during staging (p = 0.0000) and 27% during end of life (p = 0.0019). In the monitoring phase, mean intensity for ct brain, ct body, and mr body imaging decreased by 26% (p = 0.0133), 11% (p = 0.0118), and 26% (p = 0.0008), respectively. Aggregate mean intensity of imaging increased in the 13%-27% range every 3 months from 18 months before death to death, reaching 1.43 images in the final 3 months of life. Patients diagnosed in the final 18 months of life had an average of 1 additional image during both the 3 months after diagnosis (p = 0.0000) and the final 3 months before death (p = 0.0000). CONCLUSIONS: Imaging increased as temporal proximity to death decreased, and patients diagnosed near death received more staging imaging, suggesting that imaging guidelines should consider imaging intensity within the context of treatment phase. Despite the development, by multiple organizations, of appropriateness criteria to reduce imaging utilization, aggregate per-patient imaging showed insignificant changes. Simultaneous fluctuations in the intensity of imaging by modality suggest recent changes in the modalities preferred by providers.
RESUMO
Management of spatially structured species poses unique challenges. Despite a strong theoretical foundation, practitioners rarely have sufficient empirical data to evaluate how populations interact. Rather, assumptions about connectivity and source-sink dynamics are often based on incomplete, extrapolated, or modeled data, if such interactions are even considered at all. Therefore, it has been difficult to evaluate whether spatially structured species are meeting conservation goals. We evaluated how estimated metapopulation structure responded to estimates of population sizes and dispersal probabilities and to the set of populations included. We then compared outcomes of alternative management strategies that target conservation of metapopulation processes. We illustrated these concepts for Chinook salmon (Oncorhynchus tshawytscha) in the Snake River, USA. Our description of spatial structure for this metapopulation was consistent with previous characterizations. We found substantial differences in estimated metapopulation structure when we had incomplete information about all populations and when we used different sources of data (three empirical, two modeled) to estimate dispersal, whereas responses to population size estimates were more consistent. Together, these findings suggest that monitoring efforts should target all populations occasionally and populations that play key roles frequently and that multiple types of data should be collected when feasible. When empirical data are incomplete or of uneven quality, analyses using estimates produced from an ensemble of available datasets can help conservation planners and managers weigh near-term options. Doing so, we found trade-offs in connectivity and source dominance in metapopulation-level responses to alternative management strategies that suggest which types of approaches may be inherently less risky.
Assuntos
Conservação dos Recursos Naturais , Salmão , Animais , Densidade Demográfica , Dinâmica Populacional , RiosRESUMO
BACKGROUND: As awareness around infertility is increasing among patients with chronic kidney disease (CKD), ever more of them are seeking Assisted Reproductive Technology (ART). Our aim was to perform a systematic review to describe obstetric and renal outcomes in women with CKD following ART. METHODS: The following databases were searched from 1946 to May 2021: (1) Cochrane Central Register of Controlled Trials (CENTRAL), (2) Cumulative Index to Nursing and Allied Health Literature (CINAHL), (3) Embase and (4) MEDLINE. RESULTS: The database search identified 3520 records, of which 32 publications were suitable. A total of 84 fertility treatment cycles were analysed in 68 women. Median age at time of pregnancy was 32.5 years (IQR 30.0, 33.9 years). There were 60 clinical pregnancies resulting in 70 live births (including 16 multifetal births). Four women developed ovarian hyperstimulation syndrome which were associated with acute kidney injury. Hypertensive disorders complicated 26 pregnancies (38.3%), 24 (35.3%) pregnancies were preterm delivery, and low birth weight was present in 42.6% of pregnancies. Rates of live birth and miscarriage were similar for women with CKD requiring ART or having natural conception. However, more women with ART developed pre-eclampsia (p < 0.05) and had multifetal deliveries (p < 0.001), furthermore the babies were lower gestational ages (p < 0.001) and had lower birth weights (p < 0.001). CONCLUSION: This systematic review represents the most comprehensive assessment of fertility outcomes in patients with CKD following ART. However, the high reported live birth rate is likely related to reporting bias. Patient selection remains crucial in order to maximise patient safety, screen for adverse events and optimise fertility outcomes.
Assuntos
Injúria Renal Aguda , Insuficiência Renal Crônica , Lactente , Gravidez , Recém-Nascido , Humanos , Feminino , Insuficiência Renal Crônica/complicações , Insuficiência Renal Crônica/diagnóstico , Insuficiência Renal Crônica/terapia , Rim , Técnicas de Reprodução Assistida , Nascido VivoRESUMO
Initial relative mass (W(R), low v. high) and energetic trajectory in time (starved v. fed) were experimentally manipulated in bluegill Lepomis macrochirus. Fed fish starting at low W(R) grew more and gained more W(R) than fed fish starting at high W(R). Similarly, starved fish starting at high W(R) lost more mass and W(R) than did starved fish starting at low W(R). Temporal changes in other variables did not consistently match that of W(R), but, by the end of the experiment, proximate composition showed a high correlation to W(R). Regression slopes of W(R) on proximate composition increased with time in the laboratory. Differences between wild and laboratory fish appeared to result from relaxation of environmental stress. When excess resources are available such that L. macrochirus grow, condition indices will increase, but individual response will depend on initial values and thus past environmental experience.
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Composição Corporal , Meio Ambiente , Estado Nutricional , Perciformes/crescimento & desenvolvimento , Perciformes/fisiologia , Animais , Tamanho CorporalRESUMO
The retroviral transmembrane envelope protein p15E is immunosuppressive in that it inhibits immune responses of lymphocytes, monocytes, and macrophages. A region of p15E has been conserved among murine and feline retroviruses; a homologous region is also found in the transmembrane envelope proteins of the human retroviruses HTLV-I and HTLV-II and in a putative envelope protein encoded by an endogenous C-type human retroviral DNA. A peptide (CKS-17) was synthesized to correspond to this region of homology and was examined for its effects on lymphocyte proliferation. CKS-17 inhibited the proliferation of an interleukin-2-dependent murine cytotoxic T-cell line as well as alloantigen-stimulated proliferation of murine and human lymphocytes. Four other peptides, representing different regions of virus proteins, were inactive. These results suggest that the immunosuppressive portion of retroviral transmembrane envelope proteins may reside, at least in part, in a-conserved sequence represented by the CKS-17 peptide.
Assuntos
Ativação Linfocitária/efeitos dos fármacos , Peptídeos/farmacologia , Retroviridae/genética , Proteínas do Envelope Viral/farmacologia , Sequência de Aminoácidos , Animais , Linhagem Celular , Deltaretrovirus/genética , Humanos , Peptídeos e Proteínas de Sinalização Intercelular , Vírus da Leucemia Felina/genética , Vírus da Leucemia Murina/genética , Teste de Cultura Mista de Linfócitos , Linfócitos/efeitos dos fármacos , Camundongos , Camundongos Endogâmicos BALB C , Baço/citologia , Proteínas do Envelope Viral/genéticaRESUMO
The major internal virion polypeptide from feline and RD-114 type C viruses has been subjected to amino terminal sequence analyses with the Beckman automated sequencer. These proteins, as well as their homologs in rat and mouse viruses, begin with the sequence prolylleucylarginyl (Pro-Leu-Arg). Virus RD-114 differs from conventional feline type C viruses that show about 80 percent relatedness based on calculation of the minimum number of base changes to give equivalent coding for the protein segments analyzed. In addition, insertion of a gap in the RD-114 sequence is necessary to maintain positional homology. The difference between RD-114 and feline leukemia virus appears as great as the difference between mouse type C viruses and either of these two viruses. Thus, even though current evidence suggests that RD-114 is of feline origin, the sequence differences between RD-114 and conventional feline virus group-specific proteins is well beyond that based on one or a few point mutations.
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Vírus da Leucemia Felina/análise , Vírus Oncogênicos/análise , Vírus de RNA/análise , Proteínas Virais/análise , Sequência de Aminoácidos , Animais , Autoanálise , Gatos , Cromatografia Gasosa , Cromatografia em Camada Fina , Epitopos , Código Genético , Humanos , Vírus da Leucemia Felina/imunologia , Camundongos , Retroviridae/análise , Retroviridae/classificação , Retroviridae/imunologiaRESUMO
A protein designated p14 was purified from a simian immunodeficiency virus (SIVMne) and was shown by amino acid sequence analysis to be nearly identical to the predicted translational product of a unique open reading frame (X-ORF) in the nucleotide sequences of SIVmac and human immunodeficiency virus type 2 (HIV-2). Thus the X-ORF is proven to be a new retroviral gene. The p14 is present in SIVMne in molar amounts equivalent to those of the gag proteins. This is the first example of a retrovirus that contains a substantial quantity of a viral protein that is not a product of the gag, pro, pol, or env genes. SIV p14 and its homolog in HIV-2 may function as nucleic acid binding proteins since purified p14 binds to single-stranded nucleic acids in vitro. Antisera to the purified protein detected p14 in SIVMne, SIVmac, and a homologous protein (16 kilodaltons) in HIV-2 but did not react with HIV-1. Diagnostic procedures based on this novel protein will distinguish between HIV-1 and HIV-2.
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Proteínas dos Retroviridae/isolamento & purificação , Retroviridae , Sequência de Aminoácidos , Dados de Sequência Molecular , Peso Molecular , Fragmentos de Peptídeos/análiseRESUMO
Radiolabeled amino acid sequencing was used to characterize gp41, an antigen of HTLV-III/LAV, the virus believed to be the etiological agent of the acquired immune deficiency syndrome. This antigen is the one most commonly detected in immunoblot assays by sera of patients with AIDS or AIDS-related complex (ARC) and other individuals infected with HTLV-III/LAV. A mouse monoclonal antibody that was reactive with gp41 precipitated a 160-kilodalton protein (gp160) in addition to gp41, but did not precipitate a 120-kilodalton protein (gp120) from extracts of metabolically labeled cells producing HTLV-III. Extracts of infected cells that had been labeled with tritiated leucine or isoleucine were immunoprecipitated with the monoclonal antibody. The immunoprecipitates were fractionated by polyacrylamide gel electrophoresis and the p41 was eluted from the gel bands and subjected to amino-terminal radiolabeled amino acid sequencing by the semiautomated Edman degradation. Leucine residues occurred in cycles 7, 9, 12, 26, 33, and 34 among 40 cycles and isoleucine occurred in cycle 4 among 24 cycles analyzed. Comparison of the data with the deduced amino acid sequence of the env gene product of HTLV-III precisely placed gp41 in the COOH-terminal region of the env gene product. Gp160 is thus the primary env gene product and it is processed into gp120 and gp41.
Assuntos
Deltaretrovirus/genética , Genes Virais , Proteínas do Envelope Viral/genética , Síndrome da Imunodeficiência Adquirida/microbiologia , Sequência de Aminoácidos , Animais , Anticorpos Monoclonais/imunologia , Antígenos Virais/genética , Antígenos Virais/imunologia , Humanos , Camundongos , Camundongos Endogâmicos BALB CRESUMO
Approximately 80 percent of all human sera that react with antigens of HTLV-III, the etiologic agent of the acquired immune deficiency syndrome (AIDS), recognize protein bands at 66 and 51 kilodaltons. A mouse hybridoma was produced that was specific to these proteins. Repeated cloning of the hybridoma did not separate the two reactivities. The p66/p51 was purified from HTLV-III lysates by immunoaffinity chromatography and subjected to NH2-terminal Edman degradation. Single amino acid residues were obtained in 17 successive degradation cycles. The sequence determined was a perfect translation of the nucleotide sequence of a portion of the HTLV-III pol gene. The purified p66/51 had reverse transcriptase activity and the monoclonal immunoglobulin G specifically removed the enzyme activity from crude viral extract as well as purified enzyme.
Assuntos
Deltaretrovirus/enzimologia , DNA Polimerase Dirigida por RNA/imunologia , Síndrome da Imunodeficiência Adquirida/imunologia , Animais , Anticorpos Monoclonais , Antígenos Virais/genética , Antígenos Virais/imunologia , Antígenos Virais/isolamento & purificação , Sequência de Bases , Cromatografia de Afinidade , Deltaretrovirus/genética , Deltaretrovirus/imunologia , Eletroforese em Gel de Poliacrilamida , Genes Virais , Humanos , Hibridomas/imunologia , Camundongos , Camundongos Endogâmicos BALB C , DNA Polimerase Dirigida por RNA/genética , DNA Polimerase Dirigida por RNA/isolamento & purificaçãoRESUMO
Conditioned medium from human T cell leukemia virus type 2 (HTLV-II)-infected T cells supports the growth and long-term culture of cells derived from acquired immunodeficiency syndrome (AIDS)-associated Kaposi's sarcoma lesions (AIDS-KS cells). A protein of 30 kilodaltons was purified from conditioned medium that supports the growth of AIDS-KS cells. The amino-terminal sequence of this protein was identical to the amino-terminal sequence of Oncostatin M, a glycoprotein that inhibits the growth of a variety of cancer cells. Oncostatin M from conditioned medium stimulated a twofold increase in the growth of AIDS-KS cells at a concentration of less than 1 nanogram of the protein per milliliter of medium.
Assuntos
Síndrome da Imunodeficiência Adquirida/complicações , Substâncias de Crescimento/fisiologia , Peptídeos/fisiologia , Sarcoma de Kaposi/patologia , Sequência de Aminoácidos , Meios de Cultura/química , Substâncias de Crescimento/isolamento & purificação , Humanos , Dados de Sequência Molecular , Oncostatina M , Peptídeos/isolamento & purificação , Sarcoma de Kaposi/etiologia , Células Tumorais CultivadasRESUMO
Protein kinase B (PKB) is a proto-oncogene that is activated in signaling pathways initiated by phosphoinositide 3-kinase. Chromatographic separation of brain cytosol revealed a kinase activity that phosphorylated and activated PKB only in the presence of phosphatidylinositol-3,4,5-trisphosphate [PtdIns(3,4,5)P3]. Phosphorylation occurred exclusively on threonine-308, a residue implicated in activation of PKB in vivo. PtdIns(3,4,5)P3 was determined to have a dual role: Its binding to the pleckstrin homology domain of PKB was required to allow phosphorylation by the upstream kinase and it directly activated the upstream kinase.
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Fosfatos de Fosfatidilinositol/metabolismo , Fosfoproteínas , Proteínas Serina-Treonina Quinases/metabolismo , Proteínas Proto-Oncogênicas/metabolismo , Proteínas Quinases Dependentes de 3-Fosfoinositídeo , Trifosfato de Adenosina/metabolismo , Sequência de Aminoácidos , Animais , Proteínas Sanguíneas/química , Encéfalo/enzimologia , Células COS , Citosol/enzimologia , Ativação Enzimática , Humanos , Masculino , Dados de Sequência Molecular , Fosforilação , Fosfotreonina/metabolismo , Proteínas Serina-Treonina Quinases/química , Proto-Oncogene Mas , Proteínas Proto-Oncogênicas/química , Proteínas Proto-Oncogênicas c-akt , Ratos , Ratos Sprague-Dawley , Transdução de Sinais , EstereoisomerismoRESUMO
Anthrax lethal toxin, produced by the bacterium Bacillus anthracis, is the major cause of death in animals infected with anthrax. One component of this toxin, lethal factor (LF), is suspected to be a metalloprotease, but no physiological substrates have been identified. Here it is shown that LF is a protease that cleaves the amino terminus of mitogen-activated protein kinase kinases 1 and 2 (MAPKK1 and MAPKK2) and that this cleavage inactivates MAPKK1 and inhibits the MAPK signal transduction pathway. The identification of a cleavage site for LF may facilitate the development of LF inhibitors.
Assuntos
Antígenos de Bactérias , Bacillus anthracis , Toxinas Bacterianas/toxicidade , Quinases de Proteína Quinase Ativadas por Mitógeno , Proteínas Serina-Treonina Quinases/antagonistas & inibidores , Proteínas Tirosina Quinases/antagonistas & inibidores , Animais , Bacillus anthracis/enzimologia , Toxinas Bacterianas/metabolismo , Sítios de Ligação , Proteínas Quinases Dependentes de Cálcio-Calmodulina/antagonistas & inibidores , Proteínas Quinases Dependentes de Cálcio-Calmodulina/metabolismo , Linhagem Celular Transformada , Ativação Enzimática , Inibidores Enzimáticos/toxicidade , Humanos , MAP Quinase Quinase 1 , MAP Quinase Quinase 2 , Metaloendopeptidases/metabolismo , Metaloendopeptidases/toxicidade , Camundongos , Proteína Básica da Mielina/metabolismo , Oócitos/fisiologia , Fosforilação , Proteínas Serina-Treonina Quinases/química , Proteínas Serina-Treonina Quinases/genética , Proteínas Serina-Treonina Quinases/metabolismo , Proteínas Tirosina Quinases/química , Proteínas Tirosina Quinases/genética , Proteínas Tirosina Quinases/metabolismo , Proteínas Recombinantes de Fusão/metabolismo , Deleção de Sequência , Transdução de Sinais , Xenopus laevisRESUMO
INTRODUCTION: School screening and the note home (pinned to a backpack) informing parents/caregivers that their child needs to see a dentist have not been effective. OBJECTIVES: The Family Access to a Dentist Study (FADS) evaluated the effectiveness of school interventions based on the common-sense model of self-regulation (CSM) among K-4 children needing restorative treatment. METHODS: FADS was a multisite double-blind randomized controlled trial with 5 arms. FADS tested a CSM-driven referral letter and dental information guide (DIG) to move caregivers from inaccurate to accurate perceptions of dental caries. Six school districts from Ohio and Washington (14 schools) participated in school years 2015 to 2016 and 2016 to 2017. A total of 611 caregivers were randomized, and 86% (n = 597 children) completed the exit examination. The primary outcome was receipt of care based on a change in oral health status determined clinically within 1 school year. RESULTS: In accordance with our primary aims, 5 arms were collapsed into 3: CSM letter and reduced CSM letter (combined), CSM letter + DIG and reduced CSM letter + reduced DIG (combined), and standard letter. Among all sites, 39.7% received restorative care (237 of 597). Combined analysis of sites revealed that the CSM referral letter (with and without the DIG) did not increase dental visits when compared with the standard letter. However, for combined sites (East Cleveland, Ohio; Washington), the CSM + DIG increased dental visits when compared with standard letter in univariate analysis (51.3% vs. 40.9%), indicating 1.6-times increased odds of a dental visit (95% CI, 0.97 to 2.58) after imputation and adjustment for covariates. The CSM + DIG group had 1.9-times increased odds (95% CI, 1.21 to 3.08) of care when compared the CSM letter alone. CONCLUSION: A CSM-driven approach to informing caregivers of the chronic nature of caries with resources in an illustrative manner can increase the benefit of school oral health screening (ClinicalTrials.gov NCT02395120). KNOWLEDGE TRANSFER STATEMENT: A school dental referral (note home) that tells a parent that the child has cavities has not been effective. In this trial, a referral based on the common-sense model of self-regulation increased follow-up care for children with restorative needs.
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Cárie Dentária , Criança , Método Duplo-Cego , Família , Humanos , Ohio , WashingtonRESUMO
In response to NGF, the Trk receptor tyrosine kinase forms a complex with SHC, a protein that couples receptor tyrosine kinases to p21ras. Complex formation between Trk and SHC, SHC tyrosine phosphorylation, and association of SHC with Grb2 were mediated by autophosphorylation at Y490 in Trk [sequence: see text]. To determine the role of SHC and other Trk substrates in NGF signaling, Trk receptors with mutations in Y490 and Y785 (the PLC-gamma 1 association site) were introduced into PC12nnr5 cells. NGF treatment of PC12nnr5 cells expressing Trk with mutations in either substrate-binding site resulted in normal neurite outgrowth and Erk1 activity and tyrosine phosphorylation. However, PC12nnr5 cells expressing Trk with mutations at both sites failed to stably extend neurites and efficiently induce Erk1 activity and tyrosine phosphorylation in response to NGF. We postulate that Trk receptors can activate Erk1 by either SHC- or PLC-gamma 1-dependent signaling pathways. These results suggest a model whereby Trk receptors utilize at least partially redundant signal transduction pathways to mediate NGF responses.
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Fatores de Crescimento Neural/metabolismo , Proteínas/fisiologia , Receptores Proteína Tirosina Quinases/metabolismo , Transdução de Sinais , Fosfolipases Tipo C/metabolismo , Células 3T3 , Sequência de Aminoácidos , Animais , Cricetinae , Camundongos , Dados de Sequência Molecular , Mutagênese Sítio-Dirigida , Células PC12 , Fosforilação , Receptores Proteína Tirosina Quinases/genética , Tirosina/metabolismoRESUMO
The pattern of mating-type switching in cell pedigrees of the fission yeast Schizosaccharomyces pombe is dictated by the inheritance of specific DNA chains at the mating-type locus (mat1). The recombination event essential for switching is initiated by a site-specific double-strand break at mat1. The switch-activating protein, Sap1, binds in vitro to a mat1 cis-acting site that was shown earlier to be essential for efficient mating-type switching. We isolated the sap1 gene by using oligonucleotides corresponding to the amino acid sequence of purified Sap1 protein. The sequence of that gene predicted a 30-kDa protein with no significant homology to other canonical DNA-binding protein motifs. To facilitate its biochemical characterization, Sap1 was expressed in Escherichia coli. The protein expressed in bacteria displayed the same DNA-binding specificities as the protein purified from S. pombe. Interestingly, analysis of a sap1 null mutation showed that the gene is essential for growth even in a strain in which mating-type switching is prohibited because of a defect in generation of the double-strand break. Thus, the sap1 gene product implicated in mating-type switching is shown to be essential for cell viability.
Assuntos
Proteínas de Ligação a DNA/genética , Regulação Fúngica da Expressão Gênica , Genes Fúngicos , Proteínas de Schizosaccharomyces pombe , Schizosaccharomyces/crescimento & desenvolvimento , Sequência de Aminoácidos , Sequência de Bases , Clonagem Molecular , Proteínas de Ligação a DNA/isolamento & purificação , Proteínas Fúngicas/genética , Genes Fúngicos Tipo Acasalamento , Dados de Sequência Molecular , Mutagênese Insercional , Oligodesoxirribonucleotídeos/química , Estrutura Secundária de Proteína , RNA Mensageiro/genética , Schizosaccharomyces/genética , Alinhamento de Sequência , Homologia de Sequência de AminoácidosRESUMO
Molecular analysis of the human trk oncogene, a transforming gene isolated from a colon carcinoma biopsy, revealed the existence of a novel member of the tyrosine kinase gene family. This locus, which we now designate the trk proto-oncogene, codes for a protein of 790 amino acid residues that has several features characteristic of cell surface receptors. They include (i) a 32-amino-acid-long putative signal peptide, (ii) an amino-terminal moiety (residues 33 to 407) rich in consensus sites for N-glycosylation, (iii) a transmembrane domain, (iv) a kinase catalytic region highly related to that of other tyrosine kinases, and (v) a very short (15 residue) carboxy-terminal tail. Residues 1 to 392 were absent in the trk oncogene, as they were replaced by tropomyosin sequences. However, no other differences were found between the transforming and nontransforming trk alleles (residues 392 to 790), suggesting that no additional mutations are required to activate the transforming potential of this gene. The human trk proto-oncogene codes for a 140,000-dalton glycoprotein, designated gp140proto-trk. However, its primary translational product is a 110,000-dalton glycoprotein which becomes immediately glycosylated, presumably during its translocation into the endoplasmic reticulum. This molecule, designated gp110proto-trk, is further glycosylated to yield the mature form, gp140proto-trk. Both gp110proto-trk and gp140proto-trk proteins possess in vitro kinase activity specific for tyrosine residues. Finally, iodination of intact NIH 3T3 cells expressing trk proto-oncogene products indicated that only the mature form, gp140proto-trk, cross the plasma membrane, becoming exposed to the outside of the cell. These results indicate that the product of the human trk locus is a novel tyrosine kinase cell surface receptor for an as yet unknown ligand.
Assuntos
Regulação da Expressão Gênica , Proteínas Tirosina Quinases/genética , Proto-Oncogenes , Sequência de Aminoácidos , Sequência de Bases , DNA/isolamento & purificação , DNA Recombinante/análise , Vetores Genéticos , Humanos , Dados de Sequência Molecular , Plasmídeos , Testes de Precipitina , Proto-Oncogene MasRESUMO
We constructed replication-competent avian retrovirus vectors that contain two of the three known types of chicken c-ski cDNAs and a third vector that contains a truncated c-ski cDNA. We developed antisera that recognize the c-ski proteins made by the three transforming c-ski viruses. All three proteins (apparent molecular masses, 50, 60, and 90 kilodaltons) are localized primarily in the nucleus. The proteins are differentially phosphorylated; immunofluorescence also suggests that there are differences in subnuclear localization of the c-ski proteins and that c-ski protein is associated with condensed chromatin in dividing cells.
Assuntos
Proteínas de Ligação a DNA/genética , Proteínas Proto-Oncogênicas/genética , Retroviridae/genética , Sequência de Aminoácidos , Aminoácidos/análise , Animais , Anticorpos , Western Blotting , Células Cultivadas , Embrião de Galinha , Galinhas , Proteínas de Ligação a DNA/isolamento & purificação , Proteínas de Ligação a DNA/metabolismo , Fibroblastos/citologia , Fibroblastos/metabolismo , Imunofluorescência , Dados de Sequência Molecular , Fosforilação , Proteínas Proto-Oncogênicas/isolamento & purificação , Proteínas Proto-Oncogênicas/metabolismo , Proteínas Recombinantes de Fusão/análiseRESUMO
Genetic and biochemical studies have identified kinase suppressor of Ras (KSR) to be a conserved component of Ras-dependent signaling pathways. To better understand the role of KSR in signal transduction, we have initiated studies investigating the effect of phosphorylation and protein interactions on KSR function. Here, we report the identification of five in vivo phosphorylation sites of KSR. In serum-starved cells, KSR contains two constitutive sites of phosphorylation (Ser297 and Ser392), which mediate the binding of KSR to the 14-3-3 family of proteins. In the presence of activated Ras, KSR contains three additional sites of phosphorylation (Thr260, Thr274, and Ser443), all of which match the consensus motif (Px[S/T]P) for phosphorylation by mitogen-activated protein kinase (MAPK). Further, we find that treatment of cells with the MEK inhibitor PD98059 blocks phosphorylation of the Ras-inducible sites and that activated MAPK associates with KSR in a Ras-dependent manner. Together, these findings indicate that KSR is an in vivo substrate of MAPK. Mutation of the identified phosphorylation sites did not alter the ability of KSR to facilitate Ras signaling in Xenopus oocytes, suggesting that phosphorylation at these sites may serve other functional roles, such as regulating catalytic activity. Interestingly, during the course of this study, we found that the biological effect of KSR varied dramatically with the level of KSR protein expressed. In Xenopus oocytes, KSR functioned as a positive regulator of Ras signaling when expressed at low levels, whereas at high levels of expression, KSR blocked Ras-dependent signal transduction. Likewise, overexpression of Drosophila KSR blocked R7 photoreceptor formation in the Drosophila eye. Therefore, the biological function of KSR as a positive effector of Ras-dependent signaling appears to be dependent on maintaining KSR protein expression at low or near-physiological levels.
Assuntos
Proteínas Quinases Dependentes de Cálcio-Calmodulina/metabolismo , Proteínas Quinases/metabolismo , Proteínas/metabolismo , Tirosina 3-Mono-Oxigenase , Proteínas ras/metabolismo , Proteínas 14-3-3 , Células 3T3 , Animais , Sítios de Ligação , Linhagem Celular , Linhagem Celular Transformada , Drosophila melanogaster , Camundongos , Mutação , Fosforilação , Ligação Proteica , Proteínas Quinases/genética , Coelhos , SerinaRESUMO
B-Raf, a member of the Raf family of serine/threonine kinases, is expressed primarily in the brain and in the nervous system. In this study, the biochemical properties of the B-Raf protein were investigated in nerve growth factor (NGF)-responsive cell lines and in brain tissues. B-Raf was identified by using phosphopeptide mapping analysis and cDNA analysis as a 95-kDa protein which is primarily localized in the cytosol. NGF rapidly stimulated both serine and threonine phosphorylation in vivo and autophosphorylation activity in vitro of the B-Raf protein. In PC12 cells, B-Raf autokinase activity was induced by both differentiation factors and mitogens, with maximal activity observed after 5 min of factor addition. B-Raf kinase activity was also observed following NGF treatment of SH-SY5Y neuroblastoma cells and in adult mouse brain and hippocampus. Induction of B-Raf kinase activity in NGF-treated PC12 cells required expression of kinase-active trk receptors. Exogenous substrates or a peptide containing the autophosphorylation site became phosphorylated when added to immune complex kinase assays and reduced the in vitro autophosphorylation activity of B-Raf, suggesting that in vitro autophosphorylation sites and exogenous substrates compete for active sites of the B-Raf kinase. Finally, the major in vitro autophosphorylation site of B-Raf was identified as threonine 372 in the conserved region 2 domain. A threonine residue is present at similar positions in all three mammalian Raf family members and may represent a regulatory site for these proteins.