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1.
Methods Cell Biol ; 163: 197-229, 2021.
Artículo en Inglés | MEDLINE | ID: mdl-33785166

RESUMEN

The early detection and management of oral premalignant lesions (OPMDs) improve their outcomes. Animal models that mimic histological and biological processes of human oral carcinogenesis may help to improve the identification of OPMD at-risk of progression into oral squamous cell carcinoma and to develop preventive strategies for the entire field of cancerization. No animal model is perfectly applicable for investigating human oral carcinogenesis. However, the 4-nitroquinoline 1-oxide (4-NQO) mouse model is well established and mimics several morphological, histological, genomic and molecular features of human oral carcinogenesis. Some of the reasons for the success of this model include its reproducible experimental conditions with limited variation, the possibility of realizing longitudinal studies with invasive intervention or gene manipulation, and sample availability for all stages of oral carcinogenesis, especially premalignant lesions. Moreover, the role of histological and molecular alterations in the field of cancerization (i.e., macroscopically healthy mucosa exposed to a carcinogen) during oral carcinogenesis can be easily explored using this model. In this review, we discuss the advantages and drawbacks of this model for studying human oral carcinogenesis. In summary, the 4-NQO-induced murine oral cancer model is relevant for investigating human oral carcinogenesis, including the immune microenvironment, and for evaluating therapeutic and chemoprevention agents.


Asunto(s)
Carcinoma de Células Escamosas , Neoplasias de la Boca , 4-Nitroquinolina-1-Óxido/toxicidad , Animales , Carcinogénesis , Carcinógenos/toxicidad , Carcinoma de Células Escamosas/inducido químicamente , Carcinoma de Células Escamosas/genética , Ratones , Neoplasias de la Boca/inducido químicamente , Microambiente Tumoral
2.
ESMO Open ; 6(1): 100044, 2021 02.
Artículo en Inglés | MEDLINE | ID: mdl-33516148

RESUMEN

BACKGROUND: Second primary cancers (SPCs) are diagnosed in over 5% of patients after a first primary cancer (FPC). We explore here the impact of immune checkpoint inhibitors (ICIs) given for an FPC on the risk of SPC in different age groups, cancer types and treatments. PATIENTS AND METHODS: The files of the 46 829 patients diagnosed with an FPC in the Centre Léon Bérard from 2013 to 2018 were analyzed. Structured data were extracted and electronic patient records were screened using a natural language processing tool, with validation using manual screening of 2818 files of patients. Univariate and multivariate analyses of the incidence of SPC according to patient characteristics and treatment were conducted. RESULTS: Among the 46 829 patients, 1830 (3.9%) had a diagnosis of SPC with a median interval of 11.1 months (range 0-78 months); 18 128 (38.7%) received cytotoxic chemotherapy (CC) and 1163 (2.5%) received ICIs for the treatment of the FPC in this period. SPCs were observed in 7/1163 (0.6%) patients who had received ICIs for their FPC versus 437/16 997 (2.6%) patients receiving CC and no ICIs for the FPC versus 1386/28 669 (4.8%) for patients receiving neither CC nor ICIs for the FPC. This reduction was observed at all ages and for all histotypes analyzed. Treatment with ICIs and/or CC for the FPC are associated with a reduced risk of SPC in multivariate analysis. CONCLUSION: Immunotherapy with ICIs alone and in combination with CC was found to be associated with a reduced incidence of SPC for all ages and cancer types.


Asunto(s)
Inhibidores de Puntos de Control Inmunológico , Neoplasias Primarias Secundarias , Humanos , Incidencia , Neoplasias Primarias Secundarias/epidemiología
3.
J Stomatol Oral Maxillofac Surg ; 122(4): 434-440, 2021 09.
Artículo en Inglés | MEDLINE | ID: mdl-33242658

RESUMEN

The ongoing shortage in healthcare services and the increasing cancer incidence, highlight the need for new strategies to ensure optimal treatments, cares and follow-up for all patients. Digitalized healthcare, which includes various concepts (digital health, telemedicine, telemonitoring and digital therapeutics), are a promising option to meet these needs. In this scoping review, we provide an overview of the recent available research evidence on digitalized healthcare for HNC patients and caregivers. Through the interrogation of PubMed and Cochrane Library databases, a total of 32 relevant articles reporting the use of digitalized healthcare in different settings of HNC patients' care management, were analyzed. Overall, HNC patients as well as caregivers were highly satisfied, especially because digitalized healthcare allows the early detection of health disorders, improve patient's management, quality of life, self-confidence and communication. Furthermore, digitalized healthcare were significantly time- and cost-effective. While the benefits digitalized healthcare has been reported to be feasible and clinically relevant, our future efforts should focus on the demonstration of their clinical utility in well-designed clinical trials. It is tempting to anticipate that this approach will improve patients' management and quality of life and change the way patients interact with family and professional health care givers.


Asunto(s)
Neoplasias de Cabeza y Cuello , Calidad de Vida , Comunicación , Atención a la Salud , Neoplasias de Cabeza y Cuello/diagnóstico , Neoplasias de Cabeza y Cuello/epidemiología , Neoplasias de Cabeza y Cuello/terapia , Humanos
4.
Oncoimmunology ; 7(12): e1496880, 2018.
Artículo en Inglés | MEDLINE | ID: mdl-30524889

RESUMEN

Oral squamous cell carcinoma (OSCC) is a major cause of cancer-associated morbidity and mortality and may develop from oral premalignant lesions (OPL). An improved molecular classification of OPL may help refining prevention strategies. We identified two main OPL gene-expression subtypes, named immunological and classical, in 86 OPL (discovery dataset). A gene expression-based score was then developed to classify OPL samples from three independent datasets, including 17 (GSE30784),13 (GSE10174) and 15 (GSE85195) OPLs, into either one of the two gene-expression subtypes. Using the single sample gene set enrichment analysis, enrichment scores for immune-related pathways were different between the two OPL subtypes. In OPL from the discovery set, loss of heterozygosities (LOH) at 3p14, 17p13, TP53, 9p21 and 8p22 and miRNA gene expression profiles were analyzed. Deconvolution of the immune infiltrate was performed using the Microenvironment Cell Populations-counter tool. A multivariate analysis revealed that decreased miRNA-142-5p expression (P = 0.0484) and lower T-cell, monocytic and myeloid dendritic cells (MDC) immune infiltration (T-cells, P = 0.0196; CD8 T cells, P = 0.0129; MDC, P = 0.0481; and monocytes, P = 0.0212) were associated with oral cancer development in the immunological subtype only. In contrast, LOH at 3p14 (P = 0.0241), 17p13 (P = 0.0348) and TP53 (P = 0.004) were associated with oral cancer development in the classical subtype only. In conclusion, we identified 2 subtypes of OPLs, namely immune and classical, which may benefit from different and specific personalized prevention interventions.

5.
J Stomatol Oral Maxillofac Surg ; 118(4): 242-247, 2017 Sep.
Artículo en Inglés | MEDLINE | ID: mdl-28576460

RESUMEN

Oral squamous cell carcinoma (OSCC) is a major cause of cancer-associated morbidity and mortality. Although OSCC may develop from easily accessible oral preneoplastic lesions (OPLs), no intervention has been reported so far that reduces the rate of malignant transformation. A comprehensive molecular characterization of oral carcinogenesis may help refining treatment strategies both in patients with OPLs and OSCC. Herein, we review main molecular alterations occurring at different steps during oral carcinogenesis and show how molecularly-based medicine and surgery may impact the outcome of OSCC in the future.


Asunto(s)
Carcinoma de Células Escamosas/genética , Carcinoma de Células Escamosas/terapia , Perfilación de la Expresión Génica , Neoplasias de la Boca/genética , Neoplasias de la Boca/terapia , Medicina de Precisión/tendencias , Biomarcadores de Tumor/análisis , Biomarcadores de Tumor/genética , Carcinoma de Células Escamosas/diagnóstico , Transformación Celular Neoplásica/genética , Transformación Celular Neoplásica/patología , Perfilación de la Expresión Génica/métodos , Humanos , Márgenes de Escisión , Terapia Molecular Dirigida , Neoplasias de la Boca/diagnóstico , Recurrencia Local de Neoplasia/diagnóstico , Recurrencia Local de Neoplasia/genética , Recurrencia Local de Neoplasia/terapia , Estadificación de Neoplasias , Procedimientos Quirúrgicos Orales/métodos , Lesiones Precancerosas/patología , Medicina de Precisión/métodos , Transcriptoma/fisiología
6.
Ann Oncol ; 28(8): 1934-1941, 2017 Aug 01.
Artículo en Inglés | MEDLINE | ID: mdl-28460011

RESUMEN

BACKGROUND: Never-smokers and never-drinkers patients (NSND) suffering from oral squamous cell carcinoma (OSCC) are epidemiologically different from smokers drinkers (SD). We therefore hypothesized that they harbored distinct targetable molecular alterations. PATIENTS AND METHODS: Data from The Cancer Genome Atlas (TCGA) (discovery set), Gene Expression Omnibus and Centre Léon Bérard (CLB) (three validation sets) with available gene expression profiles of HPV-negative OSCC from NSND and SD were mined. Protein expression profiles and genomic alterations were also analyzed from TCGA, and a functional pathway enrichment analysis was carried out. Formalin-fixed paraffin-embedded samples from 44 OSCC including 20 NSND and 24 SD treated at CLB were retrospectively collected to perform targeted-sequencing of 2559 transcripts (HTG EdgeSeq system), and CD3, CD4, CD8, IDO1, and PD-L1 expression analyses by immunohistochemistry (IHC). Enrichment of a six-gene interferon-γ signature of clinical response to pembrozulimab (PD-1 inhibitor) was evaluated in each sample from all cohorts, using the single sample gene set enrichment analysis method. RESULTS: A total of 854 genes and 29 proteins were found to be differentially expressed between NSND and SD in TCGA. Functional pathway analysis highlighted an overall enrichment for immune-related pathways in OSCC from NSND, especially involving T-cell activation. Interferon-γ response and PD1 signaling were strongly enriched in NSND. IDO1 and PD-L1 were overexpressed and the score of response to pembrolizumab was higher in NSND than in SD, although the mutational load was lower in NSND. IHC analyses in the CLB cohort evidenced IDO1 and PD-L1 overexpression in tumor cells that was associated with a higher rate of tumor-infiltrating T-cells in NSND compared with SD. CONCLUSION: The main biological and actionable difference between OSCC from NSND and SD lies in the immune microenvironment, suggesting a higher clinical benefit of PD-L1 and IDO1 inhibition in OSCC from NSND.


Asunto(s)
Antígeno B7-H1/antagonistas & inhibidores , Carcinoma de Células Escamosas/inmunología , Indolamina-Pirrol 2,3,-Dioxigenasa/antagonistas & inhibidores , Neoplasias de la Boca/inmunología , Microambiente Tumoral , Anciano , Consumo de Bebidas Alcohólicas , Alphapapillomavirus/aislamiento & purificación , Antígeno B7-H1/genética , Carcinoma de Células Escamosas/genética , Carcinoma de Células Escamosas/virología , Estudios de Cohortes , Femenino , Perfilación de la Expresión Génica , Humanos , Indolamina-Pirrol 2,3,-Dioxigenasa/genética , Masculino , Persona de Mediana Edad , Neoplasias de la Boca/genética , Neoplasias de la Boca/virología , Fumar
7.
Br J Cancer ; 105(3): 382-92, 2011 Jul 26.
Artículo en Inglés | MEDLINE | ID: mdl-21750552

RESUMEN

BACKGROUND: To study the molecular mechanisms regulating cancer cell resistance to four different tyrosine kinase inhibitors (TKIs): erlotinib, gefitinib, vandetanib and sorafenib. METHODS: An in vitro model of acquired resistance to these TKIs was developed by continuously treating the human lung adenocarcinoma cell line CALU-3 with escalating doses of each drug. Transcriptional profiling was performed with Agilent whole genome microarrays. Western blot analysis, enzyme-linked immunosorbent (ELISA), 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) cell proliferation, migration, invasion and anchorage-independent colony growth assays were conducted in vitro and experiments with established xenografts in athymic nude mice were performed in vivo in parental (P) and TKI-resistant (R) CALU-3 cell lines. RESULTS: As compared with P-CALU-3 cells, in TKI-R CALU-3 cell lines a significant increase in the expression of activated, phosphorylated MET, IGF-1R, AKT, MEK, MAPK and of survivin was observed. Downregulation of E-cadherin and amphiregulin mRNAs and upregulation of vimentin, VE-cadherin, HIF-1α and vascular endothelial growth factor receptor-1 mRNAs were observed in all four TKI-R CALU-3 cell lines. All four TKI-R CALU-3 cells showed increased invasion, migration and anchorage-independent growth. Together, these data suggest epithelial to mesenchymal transition (EMT) in TKI-R CALU-3 cells. Treatment with several agents that target AKT, MET or IGF-1R did not affect TKI-R CALU-3 cell proliferation. In contrast, treatment with MSC19363669B and selumetinib, two selective MEK inhibitors, caused inhibition of cell proliferation, invasion, migration, anchorage-independent growth in vitro and of tumour growth in vivo of all four TKI-R CALU-3 cell lines. CONCLUSION: These data suggest that resistance to four different TKIs is characterised by EMT, which is MEK-inhibitor sensitive in human CALU-3 lung adenocarcinoma.


Asunto(s)
Adenocarcinoma/tratamiento farmacológico , Resistencia a Antineoplásicos , Neoplasias Pulmonares/tratamiento farmacológico , Quinasas Quinasa Quinasa PAM/antagonistas & inhibidores , Inhibidores de Proteínas Quinasas/uso terapéutico , Adenocarcinoma del Pulmón , Animales , Bencenosulfonatos/farmacología , Línea Celular Tumoral , Proliferación Celular/efectos de los fármacos , Transición Epitelial-Mesenquimal/efectos de los fármacos , Clorhidrato de Erlotinib , Gefitinib , Perfilación de la Expresión Génica , Humanos , Ratones , Ratones Desnudos , Niacinamida/análogos & derivados , Compuestos de Fenilurea , Piperidinas/farmacología , Piridinas/farmacología , Quinazolinas/farmacología , Sorafenib , Ensayos Antitumor por Modelo de Xenoinjerto
8.
Br J Cancer ; 103(4): 560-6, 2010 Aug 10.
Artículo en Inglés | MEDLINE | ID: mdl-20628376

RESUMEN

BACKGROUND: It can be hypothesised that inherited polymorphisms in the drug-transporter ABCB1 gene may interfere with interindividual variations in drug response in breast cancer patients. Docetaxel is a substrate for ABCB1 whose function has been shown to be modulated by oestrogen and progesterone. METHODS: Whether ABCB1 polymorphisms including T-129C, A61G, C1236T, G2677T/A and C3435T polymorphisms could account for variations in the disposition of docetaxel and whether menopausal status at the time of diagnosis might interact with this effect were analysed in women receiving neoadjuvant chemotherapy for breast cancer (n=86). RESULTS: A highly significant association was observed, but restricted to premenopausal women (n=53), between the pharmacokinetics of docetaxel and C3435T polymorphism, as patients with CC genotype had lower mean values of the area under the plasma concentration-time curve (AUC) of docetaxel than patients with CT and TT genotypes (P<0.0001). Comparison between pre- and postmenopausal women with the same C3435T genotype yielded a significant difference in docetaxel AUC only for CC genotype (P<0.0001). CONCLUSION: These results suggest that C3435T polymorphism genotyping and menopausal status at the time of diagnosis might be useful when considering chemotherapy regimens including docetaxel in breast cancer patients.


Asunto(s)
Miembro 1 de la Subfamilia B de Casetes de Unión a ATP/genética , Antineoplásicos/farmacocinética , Neoplasias de la Mama/genética , Taxoides/farmacocinética , Subfamilia B de Transportador de Casetes de Unión a ATP , Adulto , Anciano , Antineoplásicos/uso terapéutico , Área Bajo la Curva , Neoplasias de la Mama/tratamiento farmacológico , Neoplasias de la Mama/cirugía , Docetaxel , Femenino , Humanos , Persona de Mediana Edad , Terapia Neoadyuvante , Polimorfismo Genético , Posmenopausia , Premenopausia , Taxoides/uso terapéutico
9.
Oncogene ; 29(18): 2616-27, 2010 May 06.
Artículo en Inglés | MEDLINE | ID: mdl-20154724

RESUMEN

Recent studies have established that amplification of the MET proto-oncogene can cause resistance to epidermal growth factor receptor (EGFR) tyrosine kinase inhibitors (TKIs) in non-small cell lung cancer (NSCLC) cell lines with EGFR-activating mutations. The role of non-amplified MET in EGFR-dependent signaling before TKI resistance, however, is not well understood. Using NSCLC cell lines and transgenic models, we demonstrate here that EGFR activation by either mutation or ligand binding increases MET gene expression and protein levels. Our analysis of 202 NSCLC patient specimens was consistent with these observations: levels of MET were significantly higher in NSCLC with EGFR mutations than in NSCLC with wild-type EGFR. EGFR regulation of MET levels in cell lines occurred through the hypoxia-inducible factor (HIF)-1alpha pathway in a hypoxia-independent manner. This regulation was lost, however, after MET gene amplification or overexpression of a constitutively active form of HIF-1alpha. EGFR- and hypoxia-induced invasiveness of NSCLC cells, but not cell survival, were found to be MET dependent. These findings establish that, absent MET amplification, EGFR signaling can regulate MET levels through HIF-1alpha and that MET is a key downstream mediator of EGFR-induced invasiveness in EGFR-dependent NSCLC cells.


Asunto(s)
Carcinoma de Pulmón de Células no Pequeñas/patología , Receptores ErbB/fisiología , Subunidad alfa del Factor 1 Inducible por Hipoxia/fisiología , Neoplasias Pulmonares/patología , Proteínas Proto-Oncogénicas c-met/fisiología , Receptores de Factores de Crecimiento/fisiología , Animales , Hipoxia de la Célula , Línea Celular Tumoral , Receptores ErbB/antagonistas & inhibidores , Amplificación de Genes , Humanos , Subunidad alfa del Factor 1 Inducible por Hipoxia/análisis , Ratones , Invasividad Neoplásica , Proto-Oncogenes Mas , Proteínas Proto-Oncogénicas c-met/análisis , Proteínas Proto-Oncogénicas c-met/genética , Receptores de Factores de Crecimiento/análisis , Receptores de Factores de Crecimiento/genética
10.
Rev Mal Respir ; 23(2 Pt 1): 149-51, 2006 Apr.
Artículo en Francés | MEDLINE | ID: mdl-16788439

RESUMEN

BACKGROUND: Carcinomatous meningitis is a major complication in Non Small Cell Lung Cancer (NSCLC). Despite treatment with radiotherapy alone or in combination with intrathecal and systemic chemotherapy, its prognosis remains poor. OBSERVATION: We report a case of a female non-smoker with adenocarcinoma with bronchoalveolar features presenting with carcinomatous meningitis three years after the diagnosis of her primary tumour. Gefitinib treatment was proposed because of the persistence of meningitic symptoms despite cranial irradiation. Clinical response was observed within 3 weeks and lasted for 9 months. CONCLUSION: Gefitinib may be effective in treating carcinomatous meningitis complicating NSCLC and should be considered in this situation given the absence of effective alternatives.


Asunto(s)
Adenocarcinoma Bronquioloalveolar/tratamiento farmacológico , Antineoplásicos/uso terapéutico , Carcinoma de Pulmón de Células no Pequeñas/tratamiento farmacológico , Quimioterapia Adyuvante , Neoplasias Pulmonares/patología , Meningitis/tratamiento farmacológico , Inhibidores de Proteínas Quinasas/uso terapéutico , Quinazolinas/uso terapéutico , Adenocarcinoma Bronquioloalveolar/patología , Adenocarcinoma Bronquioloalveolar/radioterapia , Carboplatino/administración & dosificación , Carcinoma de Pulmón de Células no Pequeñas/patología , Carcinoma de Pulmón de Células no Pequeñas/radioterapia , Cisplatino/administración & dosificación , Terapia Combinada , Irradiación Craneana , Receptores ErbB/antagonistas & inhibidores , Femenino , Gefitinib , Humanos , Neoplasias Pulmonares/tratamiento farmacológico , Neoplasias Pulmonares/cirugía , Meningitis/radioterapia , Persona de Mediana Edad , Proteínas de Neoplasias/antagonistas & inhibidores , Paclitaxel/administración & dosificación , Cuidados Paliativos , Neumonectomía , Vinblastina/administración & dosificación , Vinblastina/análogos & derivados , Vinorelbina
11.
Br J Cancer ; 94(8): 1164-9, 2006 Apr 24.
Artículo en Inglés | MEDLINE | ID: mdl-16622440

RESUMEN

The aim of the present study was to evaluate the occult lymph node carcinomatous diffusion in head and neck squamous cell carcinoma (HNSCC). A total of 1328 lymph nodes from 31 patients treated between 2004 and 2005 were prospectively evaluated by routine haematoxylin-eosin-safran (HES) staining, immunohistochemistry (IHC) and real-time Taqman reverse-transcriptase polymerase chain reaction (real-time RT-PCR) assay. Amplification of cytokeratin 19 (CK19) mRNA transcripts using real-time RT-PCR was used to quantify cervical micrometastatic burden. The cervical lymph node metastatic rates determined by routine HES staining and real-time RT-PCR assay were 16.3 and 36.0%, respectively (P<0.0001). A potential change in the nodal status was observed in 13 (42.0%) of the 31 patients and an atypical pattern of lymphatic spread was identified in four patients (12.9%). Moreover, CK19 mRNA expression values in histologically positive lymph nodes were significantly higher than those observed in histologically negative lymph nodes (P<0.0001). These results indicate that real-time RT-PCR assay for the detection of CK19 mRNA is a sensitive and reliable method for the detection of carcinomatous cells in lymph nodes. This type of method could be used to reassess lymph node status according to occult lymphatic spread in patients with HNSCC.


Asunto(s)
Carcinoma de Células Escamosas/diagnóstico , Neoplasias de Cabeza y Cuello/diagnóstico , Queratinas/genética , Ganglios Linfáticos/patología , Metástasis Linfática/diagnóstico , ARN Mensajero/análisis , Reacción en Cadena de la Polimerasa de Transcriptasa Inversa/métodos , Adulto , Anciano , Carcinoma de Células Escamosas/secundario , Carcinoma de Células Escamosas/cirugía , Femenino , Neoplasias de Cabeza y Cuello/secundario , Neoplasias de Cabeza y Cuello/cirugía , Humanos , Inmunohistoquímica , Escisión del Ganglio Linfático , Ganglios Linfáticos/cirugía , Metástasis Linfática/patología , Masculino , Persona de Mediana Edad , Estadificación de Neoplasias , Estudios Prospectivos , ARN Mensajero/genética , Sensibilidad y Especificidad
12.
Rev Mal Respir ; 21(1): 105-16, 2004 Feb.
Artículo en Francés | MEDLINE | ID: mdl-15260043

RESUMEN

INTRODUCTION: Non-small cell lung cancer has a poor prognosis, including those with operable, apparently localised, disease. Preoperative staging investigations and histo-pathological analysis are poor at detecting small clusters of tumour cells, particularly in lymph nodes. STATE OF THE ART: New methods based on immunohistochemistry, or molecular biology, have been developed to detect these so-called micro-metastases. We present a ten-year review of the literature published on this topic. PERSPECTIVE: These publications primarily reported on the detection of micro-metastases within mediastinal lymph nodes removed at operation in order to identify patients at risk of recurrence, for whom adjuvant therapy might be offered. CONCLUSIONS: Lymph node micro-metastases have been demonstrated to be an independent prognostic factor for survival, especially in stage I patients. On the other hand, the presence of bone marrow micro-metastases did not appear to be of significant prognostic value in non-small-cell lung cancer. Finally, the clinical relevance of circulating tumour cells is still debatable, although recent published studies show interesting results.


Asunto(s)
Carcinoma de Pulmón de Células no Pequeñas/secundario , Neoplasias Pulmonares/patología , Neoplasias de la Médula Ósea/secundario , Humanos , Metástasis Linfática/diagnóstico , Células Neoplásicas Circulantes , Pronóstico
14.
J Muscle Res Cell Motil ; 17(5): 555-73, 1996 Oct.
Artículo en Inglés | MEDLINE | ID: mdl-8906623

RESUMEN

A mixture of two peptides of approximately M(r) 13000 has been isolated from a papain digest of LC2 deficient myosin. The peptides assemble into highly ordered aggregates which in one view are made up of strands of pairs of dots with an average side to side spacing of 13.0 nm and an average axial repeat of 9.0 nm. In another view there are strands of single dots with a side-to-side spacing of 7.8 nm and an axial repeat of 9.1 nm. From N-terminal peptide sequencing, the two peptides have been shown to come from regions of the myosin rod displaced by 195 residues. We have shown that either peptide alone can assemble to form the same aggregates. The 195 residue displacement of the M(r) 13000 peptides corresponds closely to the 196 residue repeat of charges along the myosin rod. This finding permits us to designate 195 residue segments of the myosin rod and to relate assembly characteristics directly to the similar 195 residue segments and 196 residue charge repeat. The most C-terminal 195 residue segment carries information for assembly into helical strands. The contiguous 195 residue segment, in major part, carries information for the unipolar assembly, characteristic of the assembly in each half of the myosin filament. The next contiguous 195 residue segment, in major part, carries information for bipolar assembly which is characteristic of the bare zone region of the filament; and for the transition from the bipolar bare zone to unipolar assembly. The effect of the eight C-terminal residues of the myosin rod on the assembly of the contiguous 195 residues has also been studied. The entire fragment of 195 + eight C-terminal residues assembled to form helical strands with an axial repeat of 30 nm. Successive deletion of charged residues changed the axial repeat of the helical strands suggesting that the charged residues at the C-terminus are involved in determining the pitch in the helical assembly of the contiguous 195 residues.


Asunto(s)
Subfragmentos de Miosina/química , Secuencia de Aminoácidos , Animales , Pollos , Electroforesis en Gel de Poliacrilamida , Datos de Secuencia Molecular , Peso Molecular , Papaína/metabolismo
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