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1.
J Am Heart Assoc ; 13(19): e031429, 2024 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-39344631

RESUMO

BACKGROUND: Chest pain (CP) in patients with nonobstructive coronary artery disease is a therapeutic challenge affecting morbidity and mortality. We aimed to identify clinical factors associated with CP in this population, hypothesizing that obesity and depressive symptoms are associated with CP. METHODS AND RESULTS: In 814 patients with angiographically confirmed nonobstructive coronary artery disease, we measured sociodemographic variables, clinical risk factors, medications, and Patient Health Questionnaire 9 scores for depressive symptoms. We assessed CP frequency and prevalence by using all items from the Seattle Angina Questionnaire angina frequency domain to generate an angina frequency composite score. In the overall sample (58.8±11.7 years old, 52.6% female), 42.8% had obesity, and 71.5% had CP, with an angina frequency composite score (SD) score of 76.4 (22.1). Compared with individuals without obesity, individuals with obesity had a higher prevalence (77.6% versus 67%, P<0.001) and more frequent CP (angina frequency composite score, 74.9 [SD, 22.2] versus 78.3 [SD, 21.9], P=0.02). Obesity was independently associated with CP occurrence (odds ratio [OR], 1.7 [95% CI, 1-2.9], P=0.04). Obesity's connection with CP was only in men: men with obesity had more frequent CP (angina frequency composite score, 75.8 [SD, 20.1] versus 82.1 [SD, 19.9], P=0.002) and more prevalent CP (79.5% versus 58.2%, P<0.001) than their counterparts insofar as men with obesity had similar CP to women. Patient Health Questionnaire 9 score (OR, 1.07 [95% CI, 1.01-1.13], P=0.03) was independently associated with CP and partly mediated the association between obesity and CP. CONCLUSIONS: Obesity and depressive symptoms were independently associated with CP in individuals with nonobstructive coronary artery disease, particularly in men, and depressive symptoms partly mediated this association.


Assuntos
Doença da Artéria Coronariana , Depressão , Obesidade , Humanos , Masculino , Feminino , Obesidade/epidemiologia , Obesidade/psicologia , Obesidade/complicações , Pessoa de Meia-Idade , Depressão/epidemiologia , Depressão/diagnóstico , Depressão/psicologia , Doença da Artéria Coronariana/epidemiologia , Doença da Artéria Coronariana/psicologia , Doença da Artéria Coronariana/complicações , Prevalência , Fatores de Risco , Idoso , Angiografia Coronária , Dor no Peito/epidemiologia , Dor no Peito/psicologia , Dor no Peito/diagnóstico , Dor no Peito/etiologia , Estudos Transversais , Angina Pectoris/epidemiologia , Angina Pectoris/psicologia , Angina Pectoris/diagnóstico
2.
JACC Adv ; 3(2): 100804, 2024 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-38939377

RESUMO

Background: Vitamin D deficiency (VDD) is associated with coronary heart disease (CHD) and poor outcomes, but supplementation does not improve prognosis. VDD has been implicated in and may promote greater risk through inflammation and impaired progenitor cell function. Objectives: The authors examined VDD, high-sensitivity C-reactive protein (hsCRP), circulating progenitor cell (CPC) counts, and outcomes in patients with CHD. They hypothesized that the higher risk with VDD is mediated by inflammation and impaired regenerative capacity. Methods: A total of 5,452 individuals with CHD in the Emory Cardiovascular Biobank had measurement of 25-hydroxyvitamin D, subsets of whom had hsCRP measurements and CPCs estimated as CD34-expressing mononuclear cell counts. Findings were validated in an independent cohort. 25-hydroxyvitamin D <20 ng/mL was considered VDD. Cox and Fine-Gray models determined associations between marker levels and: 1) all-cause mortality; 2) cardiovascular mortality; and 3) major adverse cardiovascular events, a composite of adverse CHD outcomes. Results: VDD (43.6% of individuals) was associated with higher adjusted cardiovascular mortality (HR: 1.57, 95% CI: 1.09-2.28). There were significant interactions between VDD and hsCRP and CPC counts in predicting cardiovascular mortality. Individuals with both VDD and elevated hsCRP had the greatest risk (HR: 2.82, 95% CI: 2.16-3.67). Only individuals with both VDD and low CPC counts were at high risk (HR: 2.25, 95% CI: 1.46-3.46). These findings were reproduced in the validation cohort. Conclusions: VDD predicts adverse outcomes in CHD. Those with VDD, inflammation and/or diminished regenerative capacity are at a significantly greater risk of cardiovascular mortality. Whether targeted supplementation in these high-risk groups improves risk warrants further study.

3.
Int J Cardiol ; 409: 132196, 2024 Aug 15.
Artigo em Inglês | MEDLINE | ID: mdl-38782069

RESUMO

BACKGROUND: The management of revascularization of chronic total occlusions (CTOs) remains controversial. Whether specific patients gain survival benefit from CTO revascularization remains unknown. OBJECTIVES: We investigated whether (i) patients with CTO have higher N terminal pro-brain natriuretic peptide (NT pro-BNP) levels than patients without CTO, (ii) in patients with CTO, NT pro-BNP levels predict adverse events, and (iii) those with elevated levels benefit from revascularization. METHODS: In 392 patients with stable, significant coronary artery disease (CAD) and CTO undergoing coronary angiography, rates of all-cause mortality, cardiovascular death, and a composite (cardiovascular death, myocardial infarction and heart failure hospitalizations) were investigated. Unadjusted and adjusted Cox proportional and Fine and Gray sub-distribution hazard models were performed to determine the association between NT pro-BNP levels and incident event rates in patients with CTO. RESULTS: NT pro-BNP levels were higher in patients with, compared to those without CTO (median 230.0 vs. 177.7 pg/mL, p ≤0.001). Every doubling of NT pro-BNP level in patients with CTO was associated with a > 25% higher rate of adverse events. 111 (28.5%) patients underwent CTO revascularization. In patients with elevated NT pro-BNP levels (> 125 pg/mL), those who underwent CTO revascularization had substantially lower adverse event rates compared to patients without CTO revascularization (adjusted cardiovascular death hazard ratio 0.29, 95% confidence interval (0.09-0.88). However, in patients with low NT pro-BNP levels (≤ 125 pg/mL), event rates were similar in those with and without CTO revascularization. CONCLUSION: NT pro-BNP levels can help identify individuals who may benefit from CTO revascularization.


Assuntos
Biomarcadores , Oclusão Coronária , Revascularização Miocárdica , Peptídeo Natriurético Encefálico , Fragmentos de Peptídeos , Humanos , Masculino , Feminino , Oclusão Coronária/sangue , Oclusão Coronária/cirurgia , Oclusão Coronária/diagnóstico , Pessoa de Meia-Idade , Peptídeo Natriurético Encefálico/sangue , Idoso , Fragmentos de Peptídeos/sangue , Doença Crônica , Biomarcadores/sangue , Revascularização Miocárdica/métodos , Angiografia Coronária , Resultado do Tratamento , Seguimentos , Intervenção Coronária Percutânea/métodos
4.
Int J Cardiol ; 407: 132104, 2024 Jul 15.
Artigo em Inglês | MEDLINE | ID: mdl-38677332

RESUMO

BACKGROUND: The role of circulating progenitor cells (CPC) in collateral formation that occurs in the presence of chronic total occlusions (CTO) of a coronary artery is not well established. In stable patients with a CTO, we investigated whether CPC levels are associated with (a) collateral development and (b) ischemic burden, as measured by circulating high sensitivity troponin-I (hsTn-I) levels. METHODS: CPCs were enumerated by flow cytometry as CD45med+ blood mononuclear cells expressing CD34 and both CD34 and CD133 epitopes. The association between CPC counts and both Rentrop collateral grade (0, 1, 2, or 3) and hsTn-I levels were evaluated using multivariate regression analysis, after adjusting for demographic and clinical characteristics. RESULTS: In 89 patients (age 65.5, 72% male, 27% Black), a higher CPC count was positively associated with a higher Rentrop collateral grade; [CD34+ adjusted odds ratio (OR) 1.49 95% confidence interval (CI) (0.95, 2.34) P = 0.082] and [CD34+/CD133+ OR 1.57 95% CI (1.05, 2.36) P = 0.028]. Every doubling of CPC counts was also associated with lower hsTn-I levels [CD34+ ß -0.35 95% CI (-0.49, -0.15) P = 0.002] and [CD34+/CD133+ ß -0.27 95% CI (-0.43, -0.08) P = 0.009] after adjustment. CONCLUSION: Individuals with higher CPC counts have greater collateral development and lower ischemic burden in the presence of a CTO.


Assuntos
Circulação Colateral , Oclusão Coronária , Humanos , Masculino , Circulação Colateral/fisiologia , Feminino , Oclusão Coronária/sangue , Oclusão Coronária/diagnóstico , Oclusão Coronária/fisiopatologia , Idoso , Pessoa de Meia-Idade , Doença Crônica , Células-Tronco , Circulação Coronária/fisiologia , Biomarcadores/sangue , Citometria de Fluxo/métodos
6.
Am J Cardiol ; 214: 59-65, 2024 03 01.
Artigo em Inglês | MEDLINE | ID: mdl-38195045

RESUMO

Although a chronic total occlusion (CTO) in the setting of an acute coronary syndrome is associated with greater risk, the prognosis of patients with a CTO and stable coronary artery disease (CAD) remains unknown. This study aimed to investigate adverse event rates in patients with stable CAD with and without a CTO. In 3,597 patients with stable CAD (>50% coronary luminal stenosis) who underwent cardiac catheterization, all-cause mortality, cardiovascular mortality, and the composite major adverse cardiac event (MACE) rates for cardiovascular death, myocardial infarction, and heart failure hospitalization were evaluated. Cox proportional hazards and Fine and Gray subdistribution hazard models were used to compare event-free survival in patient subsets after adjustment for covariates. Event rates were higher in patients with CTOs than in those without CTOs after adjusting for demographic and clinical characteristics (cardiovascular death hazard ratio [HR] 1.29, 95% confidence interval [CI] 1.05 to 1.57, p = 0.012). Patients with CTO revascularization had lower event rates than those of patients without CTO revascularization (cardiovascular death HR 0.43, CI 0.26 to 0.70, p = 0.001). Those with nonrevascularized CTOs were at particularly great risk when compared with those without CTO (cardiovascular death HR 1.52, CI 1.25 to 1.84, p <0.001). Moreover, those with revascularized CTOs had similar event rates to those of patients with CAD without CTOs. Patients with CTO have higher rates of adverse cardiovascular events than those of patients with significant CAD without CTO. This risk is greatest in patients with nonrevascularized CTO.


Assuntos
Doença da Artéria Coronariana , Oclusão Coronária , Estenose Coronária , Infarto do Miocárdio , Intervenção Coronária Percutânea , Humanos , Oclusão Coronária/diagnóstico , Oclusão Coronária/cirurgia , Oclusão Coronária/complicações , Fatores de Risco , Angiografia Coronária/efeitos adversos , Doença da Artéria Coronariana/complicações , Estenose Coronária/complicações , Doença Crônica , Intervenção Coronária Percutânea/efeitos adversos , Resultado do Tratamento
7.
J Am Heart Assoc ; 12(24): e031230, 2023 Dec 19.
Artigo em Inglês | MEDLINE | ID: mdl-38063161

RESUMO

BACKGROUND: Literature suggests a bidirectional association between advanced hepatic fibrosis (AHF) and coronary artery disease (CAD). We evaluated the association of AHF with immune activation, systemic inflammation, and adverse outcomes in patients with CAD. METHODS AND RESULTS: A fibrosis-4 index cutoff value ≥2.67 was used to define AHF. Circulating levels of soluble urokinase plasminogen activator receptor and hsCRP (high-sensitivity C-reactive protein) were measured as markers for immune activation and systemic inflammation, respectively. The relationship of AHF with soluble urokinase plasminogen activator receptor, hsCRP, and adverse cardiovascular outcomes was evaluated. Among 3406 participants with CAD, 479 had AHF. Participants with AHF were older; were less likely to be Black individuals; and had a lower body mass index, worse renal function, and a prior history of heart failure. In multivariable linear regression models adjusted for clinical and demographic confounders, participants with AHF had 15.6% higher soluble urokinase plasminogen activator receptor and 24.0% higher hsCRP levels. They were more likely to experience the following adverse outcomes: all-cause death (adjusted hazard ratio [HR], 1.57 ([95% CI, 1.29-1.92]; P<0.001) and cardiovascular death: (subdistribution HR, 1.50 [95% CI, 1.14-1.95]; P=0.003). Mediation analysis showed that 47.0% (95% CI, 13.6%-81.2%]; P=0.006) of the indirect effect of AHF on cardiovascular death was mediated by circulating soluble urokinase plasminogen activator receptor levels. CONCLUSIONS: AHF is independently associated with immune activation, systemic inflammation, and adverse cardiovascular outcomes in patients with CAD. The association of AHF with adverse outcomes is partly mediated by immune activation, and targeting this pathway may help reduce the residual risk in patients with CAD.


Assuntos
Doença da Artéria Coronariana , Humanos , Doença da Artéria Coronariana/diagnóstico , Proteína C-Reativa/análise , Receptores de Ativador de Plasminogênio Tipo Uroquinase , Fatores de Risco , Biomarcadores , Inflamação , Cirrose Hepática/diagnóstico
8.
J Am Heart Assoc ; 12(21): e031431, 2023 11 07.
Artigo em Inglês | MEDLINE | ID: mdl-37929763

RESUMO

Background The survival benefit of revascularization of chronic total occlusion (CTO) of the coronary arteries remains a subject of controversy. We measured high sensitivity troponin-I (hsTn-I) levels as an estimate of myocardial ischemia in patients with stable coronary artery disease, with the hypothesis that (1) patients with CTO have higher levels of hsTn-I than patients without CTO, (2) hsTn-I levels will predict adverse cardiovascular events in patients with CTO, and (3) patients with elevated hsTn-I levels will have a survival benefit from CTO revascularization. Methods and Results In 428 patients with stable coronary artery disease and CTO undergoing coronary angiography, adverse event rates were investigated. Cox proportional hazards models and Fine and Gray subdistribution hazard models were performed to determine the association between hsTn-I level and incident event rates in patients with CTO. HsTn-I levels were higher in patients with compared with those without CTO (median 6.7 versus 5.6 ng/L, P=0.002). An elevated hsTn-I level was associated with higher adverse event rates (adjusted all-cause mortality hazard ratio, 1.19 [95% CI, 1.08-1.32]; P=0.030) for every doubling of hsTn-I level. CTO revascularization was performed in 28.3% of patients. In patients with a high (>median) hsTn-I level, CTO revascularization was associated with substantially lower all-cause mortality (adjusted hazard ratio, 0.26 [95% CI, 0.08-0.88]; P=0.030) compared with those who did not undergo revascularization. In patients with a low (

Assuntos
Doença da Artéria Coronariana , Oclusão Coronária , Intervenção Coronária Percutânea , Humanos , Doença da Artéria Coronariana/complicações , Fatores de Risco , Resultado do Tratamento , Intervenção Coronária Percutânea/efeitos adversos , Angiografia Coronária/efeitos adversos , Doença Crônica , Troponina I
11.
Dermatol Surg ; 44(6): 865-869, 2018 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-29381548

RESUMO

BACKGROUND: Effective treatment of keloids is challenging because the recurrence rate after surgical excision is high. Data on the best treatment practices are lacking. OBJECTIVE: To investigate the recurrence rate after surgical excision of earlobe keloids based on a postoperative intralesional corticosteroid injection protocol. MATERIALS AND METHODS: Retrospective chart review was performed from January 1, 2005, to March 31, 2016, of patients who had excision of ear keloids within the departments of dermatology, otorhinolaryngology, and plastic surgery. The number of postoperative injections was recorded, recurrence was reported by the patient, and the efficacy of an injection protocol was evaluated. RESULTS: There were 277 charts reviewed. Appropriate data were available for 184 patients. A statistically significant difference was found with recurrence associated with a lower number of injections (p < .001). Keloids were more likely to recur if they were not treated with a planned serial injection protocol (p < .001) or if they were treated outside the department of dermatology (p < .001). CONCLUSION: Intralesional corticosteroid injection after surgical excision of earlobe keloids statistically minimizes the risk of recurrence.


Assuntos
Orelha Externa/cirurgia , Glucocorticoides/administração & dosagem , Queloide/cirurgia , Cuidados Pós-Operatórios , Adolescente , Adulto , Criança , Feminino , Seguimentos , Humanos , Injeções Intralesionais/métodos , Masculino , Recidiva , Estudos Retrospectivos , Resultado do Tratamento
13.
Cell Host Microbe ; 17(5): 642-52, 2015 May 13.
Artigo em Inglês | MEDLINE | ID: mdl-25974303

RESUMO

Toxoplasma gondii is a protozoan pathogen in the phylum Apicomplexa that resides within an intracellular parasitophorous vacuole (PV) that is selectively permeable to small molecules through unidentified mechanisms. We have identified GRA17 as a Toxoplasma-secreted protein that localizes to the parasitophorous vacuole membrane (PVM) and mediates passive transport of small molecules across the PVM. GRA17 is related to the putative Plasmodium translocon protein EXP2 and conserved across PV-residing Apicomplexa. The PVs of GRA17-deficient parasites have aberrant morphology, reduced permeability to small molecules, and structural instability. GRA17-deficient parasites proliferate slowly and are avirulent in mice. These GRA17-deficient phenotypes are rescued by complementation with Plasmodium EXP2. GRA17 functions synergistically with a related protein, GRA23. Exogenous expression of GRA17 or GRA23 alters the membrane conductance properties of Xenopus oocytes in a manner consistent with a large non-selective pore. Thus, GRA17 and GRA23 provide a molecular basis for PVM permeability and nutrient access.


Assuntos
Antígenos de Protozoários/metabolismo , Proteínas de Membrana Transportadoras/metabolismo , Toxoplasma/fisiologia , Vacúolos/parasitologia , Fatores de Virulência/metabolismo , Animais , Antígenos de Protozoários/genética , Transporte Biológico , Deleção de Genes , Teste de Complementação Genética , Proteínas de Membrana Transportadoras/genética , Camundongos , Toxoplasma/crescimento & desenvolvimento , Toxoplasma/metabolismo , Toxoplasmose Animal/parasitologia , Toxoplasmose Animal/patologia , Virulência , Fatores de Virulência/genética , Xenopus
14.
J Am Acad Dermatol ; 70(4): 699-703, 2014 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-24433875

RESUMO

BACKGROUND: Metabolic syndrome is a multifaceted disorder strongly associated with increased risk for development of cardiovascular disease. Chronic inflammatory diseases have been associated with metabolic syndrome. Hidradenitis suppurativa is a chronic inflammatory skin disease with significant physical and emotional sequelae. OBJECTIVE: We sought to investigate a possible association between hidradenitis suppurativa and metabolic syndrome. METHODS: A retrospective chart review of all dermatology clinic encounters over an 18-month period identified 366 patients with an appropriate diagnosis of hidradenitis suppurativa. A control population was created from patients seen in the same clinic during the same time period for the diagnoses of either keloids or verruca vulgaris using the matching criteria of age ±5 years, race, and gender. All participants were examined for characteristics of the metabolic syndrome as defined by the National Cholesterol Education Program Adult Treatment Program III guidelines. RESULTS: The prevalence of metabolic syndrome in patients with hidradenitis suppurativa was 50.6%, which was significantly higher than the control group at 30.2% (P < .001). LIMITATIONS: This was a retrospective review. Some participants could not be analyzed for metabolic syndrome presence as a result of missing data points. CONCLUSION: Our results indicate that patients with hidradenitis suppurativa may be at high risk for metabolic syndrome.


Assuntos
Hidradenite Supurativa/diagnóstico , Hidradenite Supurativa/epidemiologia , Síndrome Metabólica/diagnóstico , Síndrome Metabólica/epidemiologia , Adulto , Distribuição por Idade , Idoso , Estudos de Casos e Controles , Comorbidade , Intervalos de Confiança , Feminino , Hidradenite Supurativa/terapia , Humanos , Masculino , Síndrome Metabólica/terapia , Pessoa de Meia-Idade , Prevalência , Prognóstico , Valores de Referência , Estudos Retrospectivos , Medição de Risco , Índice de Gravidade de Doença , Distribuição por Sexo
15.
Int J Parasitol ; 44(2): 147-60, 2014 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-24070999

RESUMO

The rhoptries are key secretory organelles from apicomplexan parasites that contain proteins involved in invasion and modulation of the host cell. Some rhoptry proteins are restricted to the posterior bulb (ROPs) and others to the anterior neck (RONs). As many rhoptry proteins have been shown to be key players in Toxoplasma invasion and virulence, it is important to identify, understand and characterise the biological function of the components of the rhoptries. In this report, we identified putative novel rhoptry genes by identifying Toxoplasma genes with similar cyclical expression profiles as known rhoptry protein encoding genes. Using this approach we identified two new rhoptry bulb (ROP47 and ROP48) and one new rhoptry neck protein (RON12). ROP47 is secreted and traffics to the host cell nucleus, RON12 was not detected at the moving junction during invasion. Deletion of ROP47 or ROP48 in a type II strain did not show major influence in in vitro growth or virulence in mice.


Assuntos
Proteínas de Protozoários/metabolismo , Toxoplasma/metabolismo , Toxoplasmose Animal/parasitologia , Animais , Feminino , Regulação da Expressão Gênica , Camundongos , Camundongos Endogâmicos C57BL , Proteínas de Protozoários/genética , Toxoplasma/química , Toxoplasma/genética
16.
J Biol Chem ; 288(48): 34968-80, 2013 Nov 29.
Artigo em Inglês | MEDLINE | ID: mdl-24129568

RESUMO

At least a third of the human population is infected with the intracellular parasite Toxoplasma gondii, which contributes significantly to the disease burden in immunocompromised and neutropenic hosts and causes serious congenital complications when vertically transmitted to the fetus. Genetic analyses have identified the Toxoplasma ROP18 Ser/Thr protein kinase as a major factor mediating acute virulence in mice. ROP18 is secreted into the host cell during the invasion process, and its catalytic activity is required for the acute virulence phenotype. However, its precise molecular function and regulation are not fully understood. We have determined the crystal structure of the ROP18 kinase domain, which is inconsistent with a previously proposed autoinhibitory mechanism of regulation. Furthermore, a sucrose molecule bound to our structure identifies an additional ligand-binding pocket outside of the active site cleft. Mutational analysis confirms an important role for this pocket in virulence.


Assuntos
Proteínas Serina-Treonina Quinases/química , Proteínas Serina-Treonina Quinases/genética , Toxoplasma/patogenicidade , Toxoplasmose/genética , Animais , Sítios de Ligação , Cristalografia por Raios X , Análise Mutacional de DNA , Humanos , Ligantes , Camundongos , Ligação Proteica , Conformação Proteica , Estrutura Terciária de Proteína/genética , Proteínas de Protozoários , Toxoplasma/genética , Toxoplasmose/microbiologia
17.
PLoS Pathog ; 8(6): e1002784, 2012.
Artigo em Inglês | MEDLINE | ID: mdl-22761577

RESUMO

The obligate intracellular parasite Toxoplasma gondii secretes effector proteins into the host cell that manipulate the immune response allowing it to establish a chronic infection. Crosses between the types I, II and III strains, which are prevalent in North America and Europe, have identified several secreted effectors that determine strain differences in mouse virulence. The polymorphic rhoptry protein kinase ROP18 was recently shown to determine the difference in virulence between type I and III strains by phosphorylating and inactivating the interferon-γ (IFNγ)-induced immunity-related GTPases (IRGs) that promote killing by disrupting the parasitophorous vacuole membrane (PVM) in murine cells. The polymorphic pseudokinase ROP5 determines strain differences in virulence through an unknown mechanism. Here we report that ROP18 can only inhibit accumulation of the IRGs on the PVM of strains that also express virulent ROP5 alleles. In contrast, specific ROP5 alleles can reduce IRG coating even in the absence of ROP18 expression and can directly interact with one or more IRGs. We further show that the allelic combination of ROP18 and ROP5 also determines IRG evasion and virulence of strains belonging to other lineages besides types I, II and III. However, neither ROP18 nor ROP5 markedly affect survival in IFNγ-activated human cells, which lack the multitude of IRGs present in murine cells. These findings suggest that ROP18 and ROP5 have specifically evolved to block the IRGs and are unlikely to have effects in species that do not have the IRG system, such as humans.


Assuntos
Evasão da Resposta Imune/imunologia , Interferon gama/imunologia , Proteínas Serina-Treonina Quinases/imunologia , Toxoplasma/imunologia , Toxoplasmose/imunologia , Animais , Western Blotting , Cromatografia Líquida de Alta Pressão , Imunofluorescência , GTP Fosfo-Hidrolases , Ensaios de Triagem em Larga Escala , Humanos , Imunoprecipitação , Espectrometria de Massas , Camundongos , Proteínas de Protozoários , Reação em Cadeia da Polimerase Via Transcriptase Reversa , Especificidade da Espécie , Toxoplasma/patogenicidade , Virulência/imunologia
18.
J Biol Chem ; 285(17): 12638-46, 2010 Apr 23.
Artigo em Inglês | MEDLINE | ID: mdl-20190277

RESUMO

The Dbf4/Drf1-dependent kinase (DDK) is required for the initiation of DNA replication in eukaryotes. Another protein, Claspin, mediates the activation of a cellular checkpoint response to stalled replication forks and is also a regulator of replication. In this study, we found that DDK phosphorylates Claspin in vitro and forms a nuclear complex containing Cdc7, Drf1, and Claspin in Xenopus egg extracts. In addition, purified Claspin and DDK are capable of a direct in vitro interaction. We identified a conserved binding site on Claspin required for its interaction with DDK. This site corresponds to the first of two sequence repeats in the Chk1-binding domain of Claspin. Furthermore, we have established that two amino acids in this motif, Asp(861) and Gln(866), are essential for the interaction between Claspin and DDK. We found that mutant forms of Claspin incapable of interacting with DDK are still able to associate with and activate Chk1 in response to DNA replication blockages. However, Claspin-depleted egg extracts that have been reconstituted with these mutants of Claspin undergo DNA replication more slowly. These findings suggest that the interaction of DDK with Claspin mediates a checkpoint-independent function of Claspin related to DNA replication.


Assuntos
Proteínas Adaptadoras de Transdução de Sinal/metabolismo , Proteínas de Ciclo Celular/metabolismo , Proteínas Cromossômicas não Histona/metabolismo , Replicação do DNA/fisiologia , Proteínas Serina-Treonina Quinases/metabolismo , Proteínas de Xenopus/metabolismo , Proteínas Adaptadoras de Transdução de Sinal/genética , Motivos de Aminoácidos , Animais , Proteínas de Ciclo Celular/genética , Quinase 1 do Ponto de Checagem , Proteínas Cromossômicas não Histona/genética , Forminas , Humanos , Mutação , Óvulo/enzimologia , Proteínas Quinases/genética , Proteínas Quinases/metabolismo , Proteínas Serina-Treonina Quinases/genética , Proteínas de Xenopus/genética , Xenopus laevis
19.
Mol Biol Cell ; 16(11): 5269-82, 2005 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-16148040

RESUMO

Claspin is essential for the ATR-dependent activation of Chk1 in Xenopus egg extracts containing incompletely replicated DNA. Claspin associates with replication forks upon origin unwinding. We show that Claspin contains a replication fork-interacting domain (RFID, residues 265-605) that associates with Cdc45, DNA polymerase epsilon, replication protein A, and two replication factor C complexes on chromatin. The RFID contains two basic patches (BP1 and BP2) at amino acids 265-331 and 470-600, respectively. Deletion of either BP1 or BP2 compromises optimal binding of Claspin to chromatin. Absence of BP1 has no effect on the ability of Claspin to mediate activation of Chk1. By contrast, removal of BP2 causes a large reduction in the Chk1-activating potency of Claspin. We also find that Claspin contains a small Chk1-activating domain (residues 776-905) that does not bind stably to chromatin, but it is fully effective at high concentrations for mediating activation of Chk1. These results indicate that stable retention of Claspin on chromatin is not necessary for activation of Chk1. Instead, our findings suggest that only transient interaction of Claspin with replication forks potentiates its Chk1-activating function. Another implication of this work is that stable binding of Claspin to chromatin may play a role in other functions besides the activation of Chk1.


Assuntos
Proteínas Adaptadoras de Transdução de Sinal/fisiologia , Replicação do DNA , Proteínas Quinases/metabolismo , Proteínas de Xenopus/fisiologia , Proteínas Adaptadoras de Transdução de Sinal/química , Animais , Proteínas de Ciclo Celular/metabolismo , Quinase 1 do Ponto de Checagem , Cromatina/metabolismo , Citoplasma/metabolismo , DNA Polimerase II/metabolismo , Proteínas do Ovo/metabolismo , Ativação Enzimática , Modelos Biológicos , Estrutura Terciária de Proteína/fisiologia , Proteína de Replicação C/metabolismo , Xenopus/metabolismo , Proteínas de Xenopus/química , Proteínas de Xenopus/metabolismo
20.
J Biol Chem ; 278(42): 41083-92, 2003 Oct 17.
Artigo em Inglês | MEDLINE | ID: mdl-12897072

RESUMO

We have cloned a Xenopus Dbf4-related factor named Drf1 and characterized this protein by using Xenopus egg extracts. Drf1 forms an active complex with the kinase Cdc7. However, most of the Cdc7 in egg extracts is not associated with Drf1, which raises the possibility that some or all of the remaining Cdc7 is bound to another Dbf4-related protein. Immunodepletion of Drf1 does not prevent DNA replication in egg extracts. Consistent with this observation, Cdc45 can still associate with chromatin in Drf1-depleted extracts, albeit at significantly reduced levels. Nonetheless, Drf1 displays highly regulated binding to replicating chromatin. Treatment of egg extracts with aphidicolin results in a substantial accumulation of Drf1 on chromatin. This accumulation is blocked by addition of caffeine and by immunodepletion of either ATR or Claspin. These observations suggest that the increased binding of Drf1 to aphidicolin-treated chromatin is an active process that is mediated by a caffeine-sensitive checkpoint pathway containing ATR and Claspin. Abrogation of this pathway also leads to a large increase in the binding of Cdc45 to chromatin. This increase is substantially reduced in the absence of Drf1, which suggests that regulation of Drf1 might be involved in the suppression of Cdc45 loading during replication arrest. We also provide evidence that elimination of this checkpoint causes resumed initiation of DNA replication in both Xenopus tissue culture cells and egg extracts. Taken together, these observations argue that Drf1 is regulated by an intra-S-phase checkpoint mechanism that down-regulates the loading of Cdc45 onto chromatin containing DNA replication blocks.


Assuntos
Proteínas Adaptadoras de Transdução de Sinal , Proteínas de Ciclo Celular/metabolismo , Proteínas de Ciclo Celular/fisiologia , Cromatina/metabolismo , Proteínas de Ligação a DNA , Proteínas Nucleares/fisiologia , Proteínas Serina-Treonina Quinases/metabolismo , Proteínas de Xenopus , Sequência de Aminoácidos , Animais , Antimetabólitos/farmacologia , Afidicolina/farmacologia , Proteínas Mutadas de Ataxia Telangiectasia , Bromodesoxiuridina/farmacologia , Cafeína/farmacologia , Proteínas de Transporte/metabolismo , Estimulantes do Sistema Nervoso Central/farmacologia , DNA/metabolismo , DNA Complementar/metabolismo , Regulação para Baixo , Forminas , Glutationa Transferase/metabolismo , Microscopia de Fluorescência , Dados de Sequência Molecular , Proteínas Nucleares/metabolismo , Filogenia , Testes de Precipitina , Ligação Proteica , Proteínas Recombinantes de Fusão/metabolismo , Fase S , Proteínas de Saccharomyces cerevisiae/metabolismo , Homologia de Sequência de Aminoácidos , Xenopus
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