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2.
Scand J Gastroenterol ; 54(10): 1189-1198, 2019 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-31608788

RESUMO

Background: Although lichen planus (LP) is a common skin disorder, the prevalence of esophageal involvement (ELP) and its clinical manifestations are poorly defined. We aimed to establish diagnostic criteria and characterize disease outcomes of ELP.Methods: Clinical, endoscopic, histological, and immunofluorescence data from consecutive patients with known LP between 2013 and 2018 were analyzed. We established endoscopic (denudation and tearing of the mucosa, hyperkeratosis and trachealization) and histological criteria (mucosal detachment, T-lymphocytic infiltrate, intraepithelial apoptosis, dyskeratosis, and fibrinogen deposits along the basement membrane) to grade disease severity. Endoscopic findings were correlated with clinical symptoms. Response to medical therapy was monitored.Results: Fifty-two consecutive patients (median age 59.5 years) were analyzed. According to our grading system, 16 patients were considered as severe and 18 as mild ELP. Dysphagia was the only symptom which differentiated patients with severe (14/16) or mild ELP (8/18) from patients without ELP (1/18). Concomitant oral and genital involvement of LP was associated with the presence of ELP, while oral involvement alone was not. Follow-up of 14/16 patients with severe EPL for at least one year revealed that most of these patients responded to topical corticosteroids (budesonide: n = 9/10 or fluticasone n = 2/2). Three budesonide patients experienced a resolution of symptomatic esophageal stenosis.Conclusions: Esophageal involvement of LP is frequent, but may be asymptomatic. ELP can be diagnosed using the diagnostic criteria proposed here. Dysphagia and combined oral and genital manifestation are associated with ELP. Therapy with topical corticosteroids appears to be a prudent therapeutic approach for ELP.


Assuntos
Doenças do Esôfago/diagnóstico , Líquen Plano/diagnóstico , Corticosteroides/uso terapêutico , Adulto , Idoso , Idoso de 80 Anos ou mais , Anti-Inflamatórios/uso terapêutico , Doenças do Esôfago/tratamento farmacológico , Doenças do Esôfago/patologia , Esofagoscopia , Feminino , Seguimentos , Humanos , Imunossupressores/uso terapêutico , Líquen Plano/tratamento farmacológico , Líquen Plano/patologia , Masculino , Pessoa de Meia-Idade , Diagnóstico Ausente/prevenção & controle , Índice de Gravidade de Doença , Resultado do Tratamento
3.
Z Gastroenterol ; 57(4): 497-500, 2019 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-30873576

RESUMO

Juvenile polyposis syndrome is a rare autosomal-dominant disorder characterized by multiple hamartomatous polyps in the gastrointestinal tract. It is associated with an increased risk of gastrointestinal cancer. We report the case of a 49-year-old woman presenting with proximal muscle weakness, weight loss, severe anemia, and melena. One year before, the diagnosis of a "fundic gland polyposis" was presumed after endoscopic evaluation for iron deficiency anemia had shown numerous polyps limited to the gastric mucosa. On admission, the diagnosis of dermatomyositis was made based on laboratory results with a marked elevated creatine kinase as well as the presence of characteristic clinical findings and muscle histology. Upper endoscopy revealed multiple pedunculated, edematous polyps in the stomach without apparent cancerous lesions intraluminally. Infiltration of the muscular layer was not detectable on endoscopic ultrasound. Histopathological examination of the polyps showed smooth outer surfaces and multiple dilated cystic glands, consistent with hamartomatous juvenile-type polyps. Magnetic resonance imaging revealed a peritoneal mass close to the greater curvature of the stomach, which was identified as a poorly differentiated adenocarcinoma by laparoscopic sampling. Immunohistochemical analysis of resected polyps was remarkable for a loss of SMAD4 expression, a finding that is very commonly observed in patients with gastric juvenile polyposis syndrome. Despite initial treatment response to glucocorticoids and chemotherapy, the patient died 5 months later due to progressive illness. Patients with gastric juvenile polyposis and SMAD4 mutations are at a high risk of developing gastric cancer; hence, early gastrectomy should be considered.


Assuntos
Dermatomiosite/complicações , Polipose Intestinal/congênito , Polipose Intestinal/diagnóstico por imagem , Síndromes Neoplásicas Hereditárias/diagnóstico por imagem , Pólipos/complicações , Pólipos/genética , Proteína Smad4/genética , Neoplasias Gástricas/complicações , Neoplasias Gástricas/genética , Adenocarcinoma/diagnóstico , Adenocarcinoma/genética , Pólipos Adenomatosos/diagnóstico , Pólipos Adenomatosos/genética , Adolescente , Dermatomiosite/patologia , Endoscopia do Sistema Digestório , Evolução Fatal , Feminino , Humanos , Polipose Intestinal/patologia , Imageamento por Ressonância Magnética , Pessoa de Meia-Idade , Síndromes Neoplásicas Hereditárias/diagnóstico , Síndromes Neoplásicas Hereditárias/genética , Neoplasias Gástricas/patologia
4.
Strahlenther Onkol ; 195(3): 246-253, 2019 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-30353350

RESUMO

PURPOSE: To evaluate the feasibility and toxicity profile of repeated stereotactic body radiotherapy (SBRT) for recurrent primary or secondary liver tumors. METHODS: Consecutive patients with primary (hepatocellular carcinoma [HCC] or cholangiocarcinoma [CCC]) or secondary liver cancer (LM), with intrahepatic recurrence or progression after SBRT, underwent re-SBRT in 3 to 12 fractions with a median time of 15 (range 2-66) months between treatments. RESULTS: In all, 24 patients which were previously treated with SBRT (30 lesions) were retreated with SBRT for "in- and out-of-field" recurrences (2nd SBRT: n = 28, 3rd SBRT: n = 2). The median follow-up after re-irradiation was 14 months. The median prescribed dose for the first SBRT was 46.5 (range 33-66 Gy, EQD210 = 70.5) Gy and 48 (range 27-66 Gy, EQD210 = 71) Gy for the re-SBRT. The median mean liver dose (Dmean, liver) was 6 Gy (range 1-25, EQD22 = 7 Gy) for the first SBRT and 10 Gy (range 1-63 Gy, EQD22 = 9 Gy) for the re-SBRT. Of the 30 re-irradiated lesions 6 were re-irradiated in-field resulting in a median EQD22, maximum of 359 (range 120-500) Gy for both treatments, with an α/ß = 2 to account for liver parenchyma. Treatment was well tolerated. Two patients with stent placement before SBRT developed cholangitis 4 and 14 months after re-SBRT. There were no elevations of the serum liver parameters after re-SBRT. One patient developed a grade 3 gastrointestinal bleeding. There was no radiation induced liver disease (RILD) observed. CONCLUSIONS: Repeated liver SBRT is feasible, without excessive liver toxicity, when there is no considerable overlapping with pre-irradiated portions of the stomach or bowel and enough time for the liver to regenerate.


Assuntos
Neoplasias dos Ductos Biliares/radioterapia , Carcinoma Hepatocelular/radioterapia , Colangiocarcinoma/radioterapia , Neoplasias Hepáticas/radioterapia , Neoplasias Hepáticas/secundário , Radiocirurgia/métodos , Adulto , Idoso , Idoso de 80 Anos ou mais , Fracionamento da Dose de Radiação , Feminino , Seguimentos , Alemanha , Humanos , Masculino , Pessoa de Meia-Idade , Recidiva Local de Neoplasia/radioterapia , Retratamento
5.
Artigo em Inglês | MEDLINE | ID: mdl-32913998

RESUMO

PURPOSE: Dramatic advances in our understanding of the molecular pathophysiology of cancer, along with a rapidly expanding portfolio of molecular targeted drugs, have led to a paradigm shift toward personalized, biomarker-driven cancer treatment. Here, we report the 2-year experience of the Comprehensive Cancer Center Freiburg Molecular Tumor Board (MTB), one of the first interdisciplinary molecular tumor conferences established in Europe. The role of the MTB is to recommend personalized therapy for patients with cancer beyond standard-of-care treatment. METHODS: This retrospective case series includes 198 patients discussed from March 2015 through February 2017. The MTB guided individual molecular diagnostics, assessed evidence of actionability of molecular alterations, and provided therapy recommendations, including approved and off-label treatments as well as available matched clinical trials. RESULTS: The majority of patients had metastatic solid tumors (73.7%), mostly progressive (77.3%) after a mean of 2.0 lines of standard treatment. Diagnostic recommendations resulted in 867 molecular diagnostic tests for 172 patients (five per case), including exome analysis in 36 cases (18.2%). With a median turnaround time of 28 days, treatment recommendations were given to 104 patients (52.5%). These included single-agent targeted therapies (42.3%), checkpoint inhibitors (37.5%), and combination therapies (18.3%). Treatment recommendations were implemented in 33 of 104 patients (31.7%), of whom 19 (57.6%) showed stable disease or partial response, including 14 patients (7.1% of the entire population) receiving off-label treatments. CONCLUSION: Personalized extended molecular-guided patient care is effective for a small but clinically meaningful proportion of patients in challenging clinical situations. Limited access to targeted drugs, lack of trials, and submission at late disease stage prevents broader applicability, whereas genome-wide analyses are not a strict requirement for predictive molecular testing.

6.
BMC Cancer ; 17(1): 781, 2017 Nov 21.
Artigo em Inglês | MEDLINE | ID: mdl-29162055

RESUMO

BACKGROUND: To evaluate the role of ablative radiotherapy doses in the treatment of hilar or intrahepatic cholangiocarcinoma (CCC) using stereotactic body radiotherapy (SBRT). METHODS: Consecutive patients treated from 2007 to 2016 with CCC were evaluated. Local control and toxicities were assessed every 3 months according to the Response Evaluation Criteria In Solid Tumors (RECIST) and the Common Terminology Criteria for Adverse Events v4.0, respectively. Overall survival (OS), local control (LC) and progression free survival were calculated from SBRT. RESULTS: Thirty seven patients with 43 lesions were retrospectively evaluated. The median dose delivered was 45 Gy (range 25-66 Gy) in 3-12 fractions, corresponding to a median equivalent dose in 2 Gy fractions (EQD210) of 56 (range 25-85) Gy. The median follow up was 24 months. The OS at 1 year was 56% with a median OS of 14 (95% CI: 7.8-20.2) months from start of SBRT and 22 (95% CI: 17.5-26.5) months from diagnosis. Eight lesions progressed locally. The local control rate (LC) at 1 year was 78%. The median progression free survival was 9 months (95% CI 2.8-15.2) 21 patients progressed in the liver but out of field and 15 progressed distantly. SBRT was well tolerated. Three patients (9%) developed a Grade III bleeding. Seven patients developed a cholangitis, one due to progression and the other because of a stent dysfunction 2-21(median 8) months from SBRT. CONCLUSION: In patients with locally advanced cholangiocarcinoma, SBRT is a local treatment option with an acceptable toxicity profile which warrants further investigation in prospective trials.


Assuntos
Neoplasias dos Ductos Biliares/diagnóstico , Neoplasias dos Ductos Biliares/radioterapia , Colangiocarcinoma/diagnóstico , Colangiocarcinoma/radioterapia , Radiocirurgia , Adulto , Idoso , Idoso de 80 Anos ou mais , Neoplasias dos Ductos Biliares/mortalidade , Colangiocarcinoma/mortalidade , Terapia Combinada , Fracionamento da Dose de Radiação , Feminino , Humanos , Imageamento por Ressonância Magnética , Masculino , Pessoa de Meia-Idade , Estadiamento de Neoplasias , Tomografia por Emissão de Pósitrons combinada à Tomografia Computadorizada , Doses de Radiação , Radiocirurgia/efeitos adversos , Radiocirurgia/métodos , Estudos Retrospectivos , Tomografia Computadorizada por Raios X , Falha de Tratamento , Resultado do Tratamento
8.
Eur J Gastroenterol Hepatol ; 28(12): 1374-1382, 2016 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-27580215

RESUMO

OBJECTIVE: Lichen planus (LP) is a classic skin disease that can involve the skin, hair, and nails, as well as the oral and genital mucosa. Histopathology is characterized by a T-lymphocytic, lichenoid, and interface dermatitis. Multiple case reports and small case series have shown that LP can involve the esophagus. However, the diagnostic criteria, incidence, and best treatment options remain uncertain. This study aimed to refine the diagnostic criteria, estimate prevalence, and present an outlook on treatment options to prevent long-term sequelae. PATIENTS AND METHODS: Thirty-two consecutive patients with LP of the skin, hair, nails, oral mucosa, and/or genital mucosa underwent a comprehensive clinicopathologic assessment. Esophagogastroduodenoscopy was performed, and biopsies were evaluated histologically, immunohistochemically, and by direct immunofluorescence. Patients diagnosed with esophageal lichen planus (ELP) were followed up prospectively where possible. RESULTS: In total, 20 of 32 patients had ELP. Ten of these 20 patients were classified as having proven ELP, with clear-cut endoscopically visible lesions; the other 10 were classified as having probable ELP. Eight of 10 patients with proven ELP were started on new or additional therapy because of esophageal findings. Treatment with a topical budesonide formulation or systemic corticosteroids was successful in most patients with proven ELP and reversed functional esophageal stenosis. CONCLUSION: ELP can be found in more than 50% of patients with proven mucocutaneous LP when clinical and pathologic findings are correlated carefully. Topical or systemic corticosteroids are the first-line therapy for ELP. Timely medical therapy seems to prevent scarring stenosis of the esophagus.


Assuntos
Doenças do Esôfago/diagnóstico , Líquen Plano/diagnóstico , Adulto , Idoso , Biópsia , Budesonida/uso terapêutico , Endoscopia do Sistema Digestório , Doenças do Esôfago/tratamento farmacológico , Doenças do Esôfago/epidemiologia , Doenças do Esôfago/patologia , Feminino , Imunofluorescência , Glucocorticoides/uso terapêutico , Humanos , Imuno-Histoquímica , Líquen Plano/tratamento farmacológico , Líquen Plano/epidemiologia , Líquen Plano/patologia , Masculino , Pessoa de Meia-Idade , Prevalência
10.
Hepat Oncol ; 1(1): 135-142, 2014 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-30190947

RESUMO

Cholangiocarcinomas (CCCs) are rare tumors that are derived from the epithelial cell lining of the bile ducts. They can be classified as intrahepatic, extrahepatic-perihilar and extrahepatic-distal tumors. The prognosis of CCCs is poor as, in many cases, they are diagnosed at advanced stages, at which point curative surgical resection is not possible. Furthermore, most patients will experience a tumor recurrence despite initial complete CCC resection. Therefore, alternative/additional therapeutic strategies are needed to improve tumor- and recurrence-free survival after surgery as well as tumor control in patients with advanced disease. In clinical practice, apart from systemic chemotherapies for the therapeutic management of CCCs, locoregional as well as multimodal strategies are available, including external and internal radiation therapies. This review focuses on the currently available nonsurgical therapies for patients with CCCs, alone or in combination with other modalities, and on evolving therapeutic concepts that are being explored in clinical studies.

11.
PLoS One ; 7(1): e29286, 2012.
Artigo em Inglês | MEDLINE | ID: mdl-22235280

RESUMO

Fine mapping of human cytotoxic T lymphocyte (CTL) responses against hepatitis C virus (HCV) is based on external loading of target cells with synthetic peptides which are either derived from prediction algorithms or from overlapping peptide libraries. These strategies do not address putative host and viral mechanisms which may alter processing as well as presentation of CTL epitopes. Therefore, the aim of this proof-of-concept study was to identify naturally processed HCV-derived major histocompatibility complex (MHC) class I ligands. To this end, continuous human cell lines were engineered to inducibly express HCV proteins and to constitutively express high levels of functional HLA-A2. These cell lines were recognized in an HLA-A2-restricted manner by HCV-specific CTLs. Ligands eluted from HLA-A2 molecules isolated from large-scale cultures of these cell lines were separated by high performance liquid chromatography and further analyzed by electrospray ionization quadrupole time of flight mass spectrometry (MS)/tandem MS. These analyses allowed the identification of two HLA-A2-restricted epitopes derived from HCV nonstructural proteins (NS) 3 and 5B (NS31406₋1415 and NS5B2594₋2602). In conclusion, we describe a general strategy that may be useful to investigate HCV pathogenesis and may contribute to the development of preventive and therapeutic vaccines in the future.


Assuntos
Engenharia Genética/métodos , Antígeno HLA-A2/metabolismo , Hepacivirus/metabolismo , Proteínas Virais/genética , Proteínas Virais/metabolismo , Sequência de Aminoácidos , Linhagem Celular Tumoral , Mapeamento de Epitopos , Antígeno HLA-A2/genética , Antígeno HLA-A2/imunologia , Hepacivirus/imunologia , Humanos , Ligantes , Especificidade da Espécie , Linfócitos T Citotóxicos/imunologia , Linfócitos T Citotóxicos/virologia , Proteínas não Estruturais Virais/química , Proteínas não Estruturais Virais/imunologia , Proteínas Virais/imunologia
12.
J Virol ; 84(21): 11580-4, 2010 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-20739529

RESUMO

Hepatitis C virus (HCV) nonstructural protein 5B (NS5B), the viral RNA-dependent RNA polymerase (RdRp), is a tail-anchored protein with a highly conserved C-terminal transmembrane domain (TMD) that is required for the assembly of a functional replication complex. Here, we report that the TMD of the HCV RdRp can be functionally replaced by a newly identified analogous membrane anchor of the GB virus B (GBV-B) NS5B RdRp. Replicons with a chimeric RdRp consisting of the HCV catalytic domain and the GBV-B membrane anchor replicated with reduced efficiency. Compensatory amino acid changes at defined positions within the TMD improved the replication efficiency of these chimeras. These observations highlight a conserved structural motif within the TMD of the HCV NS5B RdRp that is required for RNA replication.


Assuntos
Hepacivirus/genética , RNA Viral/biossíntese , Proteínas não Estruturais Virais/fisiologia , Substituição de Aminoácidos , Sequência Conservada , Estrutura Terciária de Proteína , RNA Polimerase Dependente de RNA , Proteínas não Estruturais Virais/química , Proteínas não Estruturais Virais/genética
14.
Hepatology ; 50(1): 46-55, 2009 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-19333911

RESUMO

UNLABELLED: Coinfection with hepatitis B virus (HBV) and hepatitis C virus (HCV) has been associated with severe liver disease and frequent progression to cirrhosis and hepatocellular carcinoma. Clinical evidence suggests reciprocal replicative suppression of the two viruses, or viral interference. However, interactions between HBV and HCV have been difficult to study due to the lack of appropriate model systems. We have established a novel model system to investigate interactions between HBV and HCV. Stable Huh-7 cell lines inducibly replicating HBV were transfected with selectable HCV replicons or infected with cell culture-derived HCV. In this system, both viruses were found to replicate in the same cell without overt interference. Specific inhibition of one virus did not affect the replication and gene expression of the other. Furthermore, cells harboring replicating HBV could be infected with cell culture-derived HCV, arguing against superinfection exclusion. Finally, cells harboring replicating HBV supported efficient production of infectious HCV. CONCLUSION: HBV and HCV can replicate in the same cell without evidence for direct interference in vitro. Therefore, the viral interference observed in coinfected patients is probably due to indirect mechanisms mediated by innate and/or adaptive host immune responses. These findings provide new insights into the pathogenesis of HBV-HCV coinfection and may contribute to its clinical management in the future.


Assuntos
Hepatite B/complicações , Hepatite B/virologia , Hepatite C/complicações , Hepatite C/virologia , Interferência Viral , Células Cultivadas/virologia , Humanos
15.
Methods Mol Biol ; 510: 195-209, 2009.
Artigo em Inglês | MEDLINE | ID: mdl-19009263

RESUMO

Formation of a membrane-associated replication complex, composed of viral proteins, replicating RNA, altered cellular membranes, and other host factors, is a hallmark of all positive-strand RNA viruses. In the case of HCV, RNA replication takes place in a likely endoplasmic reticulum-derived membrane alteration referred to as the "membranous web." In vitro transcription-translation, membrane extraction and flotation analyses, immunofluorescence microscopy, fluorescent in situ hybridization, and RNA metabolic labeling followed by confocal laser scanning microscopy have yielded insights into the structure and function of the HCV replication complex. We describe these techniques and highlight selected results.


Assuntos
Hepacivirus/metabolismo , RNA Viral/biossíntese , Proteínas Virais/química , Proteínas Virais/metabolismo , Replicação Viral , Animais , Bromodesoxiuridina/metabolismo , Membrana Celular/metabolismo , Imunofluorescência , Hibridização in Situ Fluorescente , Biossíntese de Proteínas , Coloração e Rotulagem , Transcrição Gênica , Proteínas Virais/biossíntese
16.
Proc Natl Acad Sci U S A ; 105(38): 14545-50, 2008 Sep 23.
Artigo em Inglês | MEDLINE | ID: mdl-18799730

RESUMO

Hepatitis C virus (HCV) NS3-4A is a membrane-associated multifunctional protein harboring serine protease and RNA helicase activities. It is an essential component of the HCV replication complex and a prime target for antiviral intervention. Here, we show that membrane association and structural organization of HCV NS3-4A are ensured in a cooperative manner by two membrane-binding determinants. We demonstrate that the N-terminal 21 amino acids of NS4A form a transmembrane alpha-helix that may be involved in intramembrane protein-protein interactions important for the assembly of a functional replication complex. In addition, we demonstrate that amphipathic helix alpha(0), formed by NS3 residues 12-23, serves as a second essential determinant for membrane association of NS3-4A, allowing proper positioning of the serine protease active site on the membrane. These results allowed us to propose a dynamic model for the membrane association, processing, and structural organization of NS3-4A on the membrane. This model has implications for the functional architecture of the HCV replication complex, proteolytic targeting of host factors, and drug design.


Assuntos
Proteínas de Transporte/química , Proteínas de Transporte/metabolismo , Hepacivirus/metabolismo , Modelos Moleculares , Proteínas não Estruturais Virais/química , Proteínas não Estruturais Virais/metabolismo , Proteínas Virais/química , Proteínas Virais/metabolismo , Sequência de Aminoácidos , Proteínas de Transporte/genética , Análise Mutacional de DNA , Hepacivirus/química , Hepacivirus/enzimologia , Peptídeos e Proteínas de Sinalização Intracelular , Dados de Sequência Molecular , Estrutura Secundária de Proteína , Estrutura Terciária de Proteína , Proteínas da Matriz Viral/química , Proteínas da Matriz Viral/metabolismo , Proteínas Virais/genética
17.
J Virol ; 81(6): 2745-57, 2007 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-17192310

RESUMO

Nonstructural protein 5A (NS5A) is a membrane-associated essential component of the hepatitis C virus (HCV) replication complex. An N-terminal amphipathic alpha helix mediates in-plane membrane association of HCV NS5A and at the same time is likely involved in specific protein-protein interactions required for the assembly of a functional replication complex. The aim of this study was to identify the determinants for membrane association of NS5A from the related GB viruses and pestiviruses. Although primary amino acid sequences differed considerably, putative membrane anchor domains with amphipathic features were predicted in the N-terminal domains of NS5A proteins from these viruses. Confocal laser scanning microscopy, as well as membrane flotation analyses, demonstrated that NS5As from GB virus B (GBV-B), GBV-C, and bovine viral diarrhea virus, the prototype pestivirus, display membrane association characteristics very similar to those of HCV NS5A. The N-terminal 27 to 33 amino acid residues of these NS5A proteins were sufficient for membrane association. Circular dichroism analyses confirmed the capacity of these segments to fold into alpha helices upon association with lipid-like molecules. Despite structural conservation, only very limited exchanges with sequences from related viruses were tolerated in the context of functional HCV RNA replication, suggesting virus-specific interactions of these segments. In conclusion, membrane association of NS5A by an N-terminal amphipathic alpha helix is a feature shared by HCV and related members of the family Flaviviridae. This observation points to conserved roles of the N-terminal amphipathic alpha helices of NS5A in replication complex formation.


Assuntos
Membrana Celular/metabolismo , Vírus da Diarreia Viral Bovina/química , Vírus GB A/química , Vírus GB B/química , Proteínas não Estruturais Virais/química , Sequência de Aminoácidos , Aminoácidos/química , Animais , Bovinos , Linhagem Celular Tumoral , Dicroísmo Circular , Sequência Conservada , Eletroporação , Humanos , Dados de Sequência Molecular , Osteossarcoma/patologia , Peptídeos/química , Biossíntese de Proteínas , Estrutura Secundária de Proteína , Estrutura Terciária de Proteína , Tetraciclina/farmacologia , Transfecção
18.
Int J Med Sci ; 3(2): 29-34, 2006.
Artigo em Inglês | MEDLINE | ID: mdl-16614739

RESUMO

Fascinating progress in the understanding of the molecular biology of hepatitis C virus (HCV) was achieved recently. The replicon system revolutionized the investigation of HCV RNA replication and facilitated drug discovery. Novel systems for functional analyses of the HCV glycoproteins allowed the validation of HCV receptor candidates and the investigation of cell entry mechanisms. Most recently, recombinant infectious HCV could be produced in cell culture, rendering all steps of the viral life cycle, including entry and release of viral particles, amenable to systematic analysis. In this review, we summarize recent advances and discuss future research directions.

19.
Biochemistry ; 45(7): 2221-33, 2006 Feb 21.
Artigo em Inglês | MEDLINE | ID: mdl-16475810

RESUMO

Hepatitis C virus (HCV) nonstructural protein 5A (NS5A) is a monotopic membrane protein anchored to the membrane by an N-terminal in-plane amphipathic alpha-helix. This membrane anchor is essential for the assembly of a functional viral replication complex. Although amino acid sequences differ considerably, putative membrane anchors with amphipathic features were predicted in NS5A from related Flaviviridae family members, in particular bovine viral diarrhea virus (BVDV), the prototype representative of the genus Pestivirus. We report here the NMR structure of the membrane anchor 1-28 of NS5A from BVDV in the presence of different membrane mimetic media. This anchor includes a long amphipathic alpha-helix of 21 residues interacting in-plane with the membrane interface and including a putative flexible region. Molecular dynamic simulation at a water-dodecane interface used to mimic the surface separating a lipid bilayer and an aqueous medium demonstrated the stability of the helix orientation and the location at the hydrophobic-hydrophilic interface. The flexible region of the helix appears to be required to allow the most favorable interaction of hydrophobic and hydrophilic side chain residues with their respective environment at the membrane interface. Despite the lack of amino acid sequence similarity, this amphipathic helix shares common structural features with that of the HCV counterpart, including a stable, hydrophobic N-terminal segment separated from the more hydrophilic C-terminal segment by a local, flexible region. These structural conservations point toward conserved roles of the N-terminal in-plane membrane anchors of NS5A in replication complex formation of HCV, BVDV, and other related viruses.


Assuntos
Membrana Celular/metabolismo , Vírus da Diarreia Viral Bovina/química , Proteínas não Estruturais Virais/química , Sequência de Aminoácidos , Simulação por Computador , Modelos Moleculares , Dados de Sequência Molecular , Ressonância Magnética Nuclear Biomolecular
20.
Hepatology ; 42(3): 732-5, 2005 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-16116650

RESUMO

Hepatitis C virus (HCV) is a human pathogen affecting nearly 3% of the world's population. Chronic infections can lead to cirrhosis and liver cancer. The RNA replication machine of HCV is a multi-subunit membrane-associated complex. The nonstructural protein NS5A is an active component of HCV replicase, as well as a pivotal regulator of replication and a modulator of cellular processes ranging from innate immunity to dysregulated cell growth. NS5A is a large phosphoprotein (56-58 kd) with an amphipathic -helix at its amino terminus that promotes membrane association. After this helix region, NS5A is organized into 3 domains. The N-terminal domain (domain I) coordinates a single zinc atom per protein molecule. Mutations disrupting either the membrane anchor or zinc binding of NS5A are lethal for RNA replication. However, probing the role of NS5A in replication has been hampered by a lack of structural information about this multifunctional protein. Here we report the structure of NS5A domain I at 2.5-A resolution, which contains a novel fold, a new zinc-coordination motif, and a disulfide bond. We use molecular surface analysis to suggest the location of protein-, RNA-, and membrane-interaction sites.


Assuntos
Hepacivirus/enzimologia , Proteínas não Estruturais Virais/química , Sítios de Ligação , Dissulfetos/análise , Modelos Moleculares , Fragmentos de Peptídeos/química , Conformação Proteica , RNA Polimerase Dependente de RNA/química , Zinco/metabolismo
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