RESUMEN
Familial gastrointestinal stromal tumours (GISTs) are rare but otherwise well-characterized tumour syndromes, most commonly occurring on a background of germline-activating mutations in the tyrosine kinase receptor c-KIT. The associated clinical spectrum reflects the constitutive activation of this gene product across a number of cell lines, generating gain-of-function phenotypes in interstitial cells of Cajal (GIST and dysphagia), mast cells (mastocytosis) and melanocytes (hyperpigmentation). We report a three-generation kindred harbouring a c-KIT germline-activating mutation resulting in multifocal GISTs, dysphagia and a complex melanocyte hyperpigmentation and hypopigmentation disorder, the latter with features typical of those observed in Waardenburg type 2 syndrome (WS2F). Sequencing of genes known to be causative for WS [microphthalmia transcription factor (MITF), Pax3, Sox10, SNAI2 ] failed to show any candidate mutations to explain this complex cutaneous depigmentation phenotype. Our case report conclusively expands the clinical spectrum of familial GISTs and shows a hitherto unrecognized link to WS. Possible mechanisms responsible for this novel cause of WS2F will be discussed.
Asunto(s)
Tumores del Estroma Gastrointestinal/genética , Síndromes Neoplásicos Hereditarios/genética , Síndrome de Waardenburg/genética , Alelos , Trastornos de Deglución/genética , Trastornos de Deglución/patología , Tumores del Estroma Gastrointestinal/patología , Mutación de Línea Germinal , Humanos , Hiperplasia , Células Intersticiales de Cajal/patología , Masculino , Persona de Mediana Edad , Mutación Missense , Plexo Mientérico/patología , Síndromes Neoplásicos Hereditarios/patología , Linaje , Fenotipo , Proteínas Proto-Oncogénicas c-kit/genética , Proteínas Proto-Oncogénicas c-kit/metabolismo , Análisis de Secuencia de ADN , Síndrome de Waardenburg/patologíaRESUMEN
Children with intellectual disability, dysmorphic features, malformations and/or growth abnormalities frequently display normal karyotypes. Recent studies have shown that genome-wide single nucleotide polymorphism (SNP) arrays can be effective in detecting abnormalities involving copy number variation (CNV), deletions, duplications and loss of heterozygosity (LOH) that routine cytogenetic tests fail to identify. Five patients with various degrees of intellectual disability and/or dysmorphic features and other malformations were whole-genome genotyped using the Human-1 Genotyping BeadChip--Exon-Centrix 100K SNP arrays (Illumina). All patients had undergone routine cytogenetic testing; four patients had normal karyotypes, while one patient had an apparently balanced complex translocation involving chromosomes 1q25, 1q32, 2q23, 7q22 and 16q24. We detected deletions on chromosome 1q44 and 13q31.1 in one patient, and LOH of the entire chromosome 2 in another patient, both with cytogenetically normal karyotypes. The patient with the complex translocation had a deletion on chromosome 7q22.2-22.3, which is in conjunction with one of the translocation breakpoints. Our findings provide further evidence of there being a critical region for the development of microcephaly and corpus callosum abnormalities in children with distal 1q deletions. We have also shown that apparently balanced complex translocations might not be balanced at the DNA level, and we report the fourth case of paternal uniparental disomy of chromosome 2. The results of this study suggest that it may be desirable to investigate idiopathic mental retardation using genome-wide SNP arrays, in conjunction with other cytogenetic and molecular techniques.
Asunto(s)
Cromosomas Humanos Par 1 , Cromosomas Humanos Par 2 , Eliminación de Secuencia , Translocación Genética , Disomía Uniparental , Adolescente , Alelos , Niño , Padre , Femenino , Dosificación de Gen , Frecuencia de los Genes , Humanos , Lactante , Pérdida de Heterocigocidad , Masculino , Análisis de Secuencia por Matrices de Oligonucleótidos , Fenotipo , Polimorfismo de Nucleótido SimpleRESUMEN
Hereditary non-polyposis colorectal cancer (HNPCC) is an autosomal dominantly inherited syndrome caused by germline mutations in mismatch repair (MMR) genes. HNPCC patients have a lifetime risk of 80% of developing colorectal cancer (CRC); however the likely age of onset is difficult to predict. A single C>T polymorphism located within the promoter region of the DeltaDNMT3B gene has recently been reported to be associated with a significant increase to the risk of early onset CRC. In this study we determined the DeltaDNMT3B genotype in 404 confirmed HNPCC participants (total of 194 CRC cases) from Australia (203) and Poland (201). From the total number of participants there were 194 diagnosed cases of CRC and 210 healthy MMR gene mutation carriers. The study was undertaken to assess whether the reported effect observed in a previous study of 146 HNPCC patients is consistent in a larger separate and unrelated participant cohort. Through the statistical tests of Kaplan-Meier survival analysis and Cox hazard regression models we did not observe any significant association between the DeltaDNMT3B C>T SNP and early onset CRC in HNPCC patients.
Asunto(s)
Neoplasias Colorrectales Hereditarias sin Poliposis/genética , ADN (Citosina-5-)-Metiltransferasas/genética , Polimorfismo de Nucleótido Simple , Adolescente , Adulto , Edad de Inicio , Anciano , Femenino , Predisposición Genética a la Enfermedad , Heterocigoto , Humanos , Estimación de Kaplan-Meier , Masculino , Persona de Mediana Edad , Polimorfismo de Longitud del Fragmento de Restricción , Modelos de Riesgos Proporcionales , ADN Metiltransferasa 3BAsunto(s)
Proteína BRCA1/genética , Neoplasias de la Mama/congénito , ADN Complementario/genética , Intrones , ARN Mensajero/genética , Adulto , Secuencia de Bases , Neoplasias de la Mama/genética , Neoplasias de la Mama/patología , Análisis Mutacional de ADN , Femenino , Humanos , Persona de Mediana Edad , Datos de Secuencia Molecular , Mutagénesis Insercional , Linaje , Empalme del ARNRESUMEN
BACKGROUND: The receptor tyrosine kinase c-KIT plays a key role in normal mast cell development. Point mutations in c-KIT have been associated with sporadic or familial mastocytosis. OBJECTIVES: Two unrelated pairs of apparently identical twins affected by cutaneous mastocytosis attending the Mastocytosis Clinic at the Royal Children's Hospital, Melbourne, provided an opportunity to assess the possible contribution of c-KIT germline mutations or polymorphisms in this disease. METHODS: Tissue biopsy, blood and/or buccal swab specimens were collected from 10 children with mastocytosis. To detect germline mutations/polymorphisms in c-KIT, we studied all coding exons by denaturing high pressure liquid chromatography. Exons showing mismatches were examined by direct sequencing. The influence of the substitution identified was further examined by expressing the variant form of c-KIT in factor-dependent FDC-P1 cells. RESULTS: In both pairs of twins, a heterozygous ATG to CTG transition in codon 541 was observed, resulting in the substitution of a methionine residue in the transmembrane domain by leucine (M541L). In each case, one parent was also heterozygous for this allele. Expression of M541L KIT in FDC-P1 cells enabled them to grow in human KIT ligand (stem cell factor, SCF) but did not confer factor independence. Compared with cells expressing wild-type KIT at a similar level, M541L KIT-expressing cells displayed enhanced growth at low levels of SCF, and heightened sensitivity to the KIT inhibitor, imatinib mesylate. CONCLUSIONS: The data suggest that the single nucleotide polymorphism resulting in the substitution M541L may predispose to paediatric mastocytosis.
Asunto(s)
Sustitución de Aminoácidos , Enfermedades en Gemelos/genética , Mastocitosis/genética , Polimorfismo Genético , Proteínas Proto-Oncogénicas c-kit/genética , Adolescente , Benzamidas , Proliferación Celular , Niño , Preescolar , Exones/genética , Femenino , Humanos , Mesilato de Imatinib , Lactante , Masculino , Mastocitosis/metabolismo , Piperazinas/farmacología , Reacción en Cadena de la Polimerasa , Proteínas Proto-Oncogénicas c-kit/metabolismo , Pirimidinas/farmacología , Gemelos MonocigóticosRESUMEN
The finding that codons for hydrophobic and hydrophilic amino acids are generally complemented by codons for hydrophilic and hydrophobic amino acids respectively has led to a novel observation. The antisense peptides coded for by the complementary DNA strand of biologically active peptides are able to bind their active sense counterparts with high specificity. Sense-antisense relationships have been observed in several peptide species as well as in receptor-ligand interactions. The idea that sense-antisense interactions are biologically relevant and indeed feasible among complex molecules prompts the examination of virus-host cell interactions. We propose such a sense-antisense interaction exists between the HIV glycoprotein gp120 and the intracellular domain of the HIV receptor CD4. This interaction is at a site which may be occupied by the proto oncogene product p56lck.
Asunto(s)
Proteína gp120 de Envoltorio del VIH/genética , VIH-1/genética , Secuencia de Aminoácidos , Secuencia de Bases , Sitios de Unión , Antígenos CD4/genética , Antígenos CD4/metabolismo , Codón/genética , ADN sin Sentido/genética , ADN Viral/genética , Proteína gp120 de Envoltorio del VIH/metabolismo , Infecciones por VIH/genética , Infecciones por VIH/inmunología , Infecciones por VIH/metabolismo , Humanos , Proteína Tirosina Quinasa p56(lck) Específica de Linfocito , Datos de Secuencia Molecular , Proteínas Oncogénicas Virales/genética , Proteínas Oncogénicas Virales/metabolismo , Péptidos/genética , Péptidos/metabolismo , Proteínas Tirosina Quinasas/genética , Proteínas Tirosina Quinasas/metabolismo , Proto-Oncogenes MasRESUMEN
Despite the routine nature of comparing sequence variations identified during clinical testing to database records, few databases meet quality requirements for clinical diagnostics. To address this issue, The Royal College of Pathologists of Australasia (RCPA) in collaboration with the Human Genetics Society of Australasia (HGSA), and the Human Variome Project (HVP) is developing standards for DNA sequence variation databases intended for use in the Australian clinical environment. The outputs of this project will be promoted to other health systems and accreditation bodies by the Human Variome Project to support the development of similar frameworks in other jurisdictions.
RESUMEN
The genetic predisposition Peutz-Jeghers Syndrome (PJS) has been shown to be associated with mutations in the serine threonine kinase 11 (STK11) gene but only a proportion of probands have been shown to harbour changes in the gene. The remaining patients were proposed to be either associated with a second PJS gene or they harboured more cryptic mutations within the STK11 gene itself. With the introduction of the multiplex ligation probe amplification (MLPA) assay, large sequence losses or gains can be more readily identified. In this report we have screened 33 PJS patients from unrelated families, employing a combination of denaturing high-performance liquid chromatography, direct DNA sequencing and the MLPA assay to identify deleterious changes in the STK11 gene. The results revealed that 24 (73%) of patients diagnosed with PJS-harboured pathogenic mutations in the STK11 gene, including 10 (36%) with exonic or whole-gene deletions. No phenotypic differences were identified in patients harbouring large deletions in the STK11 gene compared to patients harbouring missense or nonsense mutations. Mutation analysis in PJS should include techniques such as MLPA to identify large exonic or whole-gene deletions and rearrangements. The high proportion of families with identifiable mutations in the STK11 gene using this range of techniques suggests that most, if not all PJS, is attributable to mutations in the STK11 gene, perhaps including as yet undiscovered changes in promoter or enhancer sequences or other cryptic changes.
Asunto(s)
Mutación , Síndrome de Peutz-Jeghers/genética , Proteínas Serina-Treonina Quinasas/genética , Quinasas de la Proteína-Quinasa Activada por el AMP , Adolescente , Adulto , Australia , Niño , Preescolar , Análisis Mutacional de ADN , Exones , Femenino , Eliminación de Gen , Humanos , Masculino , Persona de Mediana Edad , Técnicas de Amplificación de Ácido Nucleico , Síndrome de Peutz-Jeghers/enzimología , Eliminación de SecuenciaRESUMEN
After one subject withdrew from an original group of twelve, eleven children with severe nocturnal enuresis were successfully treated by the Dry-Bed method. The children were aged five to nine years. The group median for the duration of treatment was four weeks, dryness being defined as two successive weeks without a bed-wetting incident. Training periods ranged from two to twenty weeks. Subsequently, two subjects relapsed, although organic and psychiatric factors respectively were probably responsible. At nine-month follow-up 73% of subjects were completely dry. The procedure made heavy demands on parents and clinician; especially in its initial phase. It was suggested that further feasibility studies are required of te Dry-Bed method of treatment in everyday service contexts.
Asunto(s)
Terapia Conductista/métodos , Enuresis/terapia , Niño , Preescolar , Enuresis/psicología , Femenino , Estudios de Seguimiento , Humanos , Masculino , InvestigaciónRESUMEN
Here we describe the isolation and characterization of a Triton X-100-insoluble fraction isolated from lysates of platelets by flotation in sucrose gradients. Transmission electron microscopy of the insoluble material revealed a heterogeneous population of vesicles ranging in size from 20 to 1000 nm, and Western blot analyses of platelet lysates for the caveolae structural coat protein, caveolin/VIP21, were negative. Biochemical characterization of the Triton X-100-insoluble fraction showed it to be cholesterol-rich, greatly and specifically enriched in the plasma membrane glycoprotein CD36, and also to contain Src and the Src-related kinase, Lyn. CD36 within this fraction is shown to be palmitoylated, but the fraction itself is not generally enriched in palmitoylated platelet proteins. These results suggest that this fraction represents caveolin-negative, CD36-rich microdomains in the resting platelet membrane. CD36 can form associations with certain Src-related kinases and can signal to activate platelets. These results suggest the possibility that such microdomains are implicated in platelet activation.
Asunto(s)
Plaquetas/química , Antígenos CD36/sangre , Caveolinas , Membrana Celular/química , Plaquetas/inmunología , Western Blotting , Caveolina 1 , Membrana Celular/inmunología , Electroforesis en Gel de Poliacrilamida , Fluorometría , Humanos , Proteínas de la Membrana/análisis , Octoxinol , Complejo GPIb-IX de Glicoproteína Plaquetaria/análisis , Proteínas Proto-Oncogénicas pp60(c-src)/análisis , Solubilidad , Familia-src Quinasas/análisisRESUMEN
The progression of colon cancer has been linked to both cell adhesion molecules called integrins and matrix-degrading enzymes called metalloproteinases. Herein we report that the alpha v beta 6 integrin expressed in colon cancer cells induces gelatinase B secretion through the C-terminal cytoplasmic extension unique to the beta 6 integrin subunit, and that this ligand-independent event involves activation of the protein-kinase-C pathway.
Asunto(s)
Antígenos de Neoplasias , Colagenasas/metabolismo , Neoplasias del Colon/metabolismo , Integrinas/metabolismo , Transducción de Señal , Humanos , Ligandos , Metaloproteinasa 9 de la Matriz , Células Tumorales CultivadasRESUMEN
Hereditary non-polyposis colorectal cancer (HNPCC) is an autosomal dominant, inherited condition that is characterized primarily by the development of early-onset colorectal cancer and a number of other epithelial malignancies. The underlying genetic basis of the disease is associated with a breakdown of DNA-mismatch repair. There are many genes involved in DNA-mismatch repair, and five of them have been implicated in HNPCC. Two of the genes (hMSH2 and hMLH1) account for the majority of HNPCC families (approximately 60%), and it is not known what the exact contributions of the remaining three genes (hPMS1, hPMS2, and hMSH6) are in relation to this condition. In addition, a sixth gene (hEXO1) has been associated with a disease phenotype that is consistent with HNPCC. Current estimates suggest that all four of these genes, combined, may account for up to 5% of families. In this report, we examine the contribution of hPMS2 and hEXO1 to a well-defined set of families that fulfill the diagnostic criteria for HNPCC. The genes, hPMS2 and hEXO1, were studied by denaturing high performance liquid chromatography (DHPLC) analysis in 21 families that have previously been determined not to have mutations in hMSH2 or hMLH1. hPMS2 accounts for a small proportion of HNPCC families, and none were deemed to be associated with hEXO1. Mutations in hPMS2 appear to account for a small proportion of families adhering to the Amsterdam II criteria, whereas hEXO1 does not appear to be associated with HNPCC.
Asunto(s)
Adenosina Trifosfatasas/genética , Neoplasias Colorrectales Hereditarias sin Poliposis/genética , Enzimas Reparadoras del ADN/genética , Proteínas de Unión al ADN/genética , Exodesoxirribonucleasas/genética , Mutación/fisiología , Proteínas Adaptadoras Transductoras de Señales , Adulto , Anciano , Proteínas Portadoras , Cromatografía Líquida de Alta Presión , Neoplasias Colorrectales Hereditarias sin Poliposis/epidemiología , Análisis Mutacional de ADN , Cartilla de ADN , Reparación del ADN/genética , Salud de la Familia , Predisposición Genética a la Enfermedad/genética , Humanos , Persona de Mediana Edad , Endonucleasa PMS2 de Reparación del Emparejamiento Incorrecto , Epidemiología Molecular , Homólogo 1 de la Proteína MutL , Proteína 2 Homóloga a MutS , Proteínas de Neoplasias/genética , Proteínas Nucleares , Proteínas Proto-Oncogénicas/genéticaRESUMEN
Familial adenomatous polyposis (FAP) is characterised by the presence of profuse colonic carpeting of adenomas throughout the entire colon and rectum. The genetic basis of FAP has been shown to be primarily associated with germline mutations in the APC gene. Notwithstanding, several reports have been published indicating that there is genetic heterogeneity in FAP and that the most likely explanation is the existence of another gene. In this report we further delineate the genotype/phenotype correlation in families that harbour germline mutations in the APC gene and identify some previously unreported changes in the APC gene which predispose to an attenuated disease phenotype. From 53 index patients diagnosed with either FAP or attenuated FAP, 27 harboured changes in the APC gene. The remaining 26 patients were further subgrouped according to their colonic phenotype. There were nine patients with a mixed hyperplastic/adenomatous colonic phenotype and there were 17 patients with an adenomatous colonic phenotype. Evaluation of the disease characteristics of these patients and their families is presented which may aid in the identification of new genes associated with colonic polyposis.
Asunto(s)
Poliposis Adenomatosa del Colon/genética , Heterogeneidad Genética , Índice de Severidad de la Enfermedad , Adolescente , Adulto , Niño , Preescolar , Femenino , Genes APC/genética , Genotipo , Mutación de Línea Germinal/genética , Humanos , Masculino , Persona de Mediana Edad , Linaje , Fenotipo , Reacción en Cadena de la PolimerasaRESUMEN
Allergic bronchopulmonary aspergillosis (ABPA) is a hypersensitivity reaction to the fungus Aspergillus fumigatus, causing severe asthma that may progress to bronchiectasis. Sputum neutrophilia can occur in association with sputum eosinophilia and correlates with the degree of bronchiectasis. The mechanisms of sputum neutrophilia in ABPA are not known. The aim of this study was to investigate the role of the chemokine interleukin (IL)-8 in sputum neutrophilia in ABPA. Induced sputum was obtained from subjects with ABPA (n=29), and compared to nonsensitised asthma (n=9) and healthy controls (n=21). Semiquantitative polymerase chain reaction was used to assess IL-8 gene expression in induced sputum and IL-8 protein was measured by enzyme-linked immunosorbent assay. Sputum IL-8 protein was significantly higher in ABPA compared to asthma and controls. IL-8 messenger ribonucleic acid/glyceraldehyde-3-phosphate dehydrogenase ratio was elevated in ABPA compared to asthma and controls. Sputum IL-8 correlated with sputum neutrophils, matrix metalloproteinase-9 levels and forced expiratory volume in one second. Interleukin-8 gene expression and protein release were increased in allergic bronchopulmonary aspergillosis and correlated with airway neutrophilia and airway obstruction. The interleukin-8-mediated neutrophil influx in allergic bronchopulmonary aspergillosis may induce lung damage via release of matrix metalloproteinase-9, potentially leading to bronchiectasis.
Asunto(s)
Aspergilosis Broncopulmonar Alérgica/enzimología , Aspergilosis Broncopulmonar Alérgica/inmunología , Aspergillus fumigatus , Asma/inmunología , Interleucina-8/genética , Metaloproteinasa 9 de la Matriz/metabolismo , Neutrófilos/inmunología , Esputo/inmunología , Adulto , Análisis de Varianza , Aspergilosis Broncopulmonar Alérgica/diagnóstico por imagen , Aspergillus fumigatus/inmunología , Estudios de Casos y Controles , Distribución de Chi-Cuadrado , Ensayo de Inmunoadsorción Enzimática , Eosinófilos/inmunología , Femenino , Expresión Génica , Humanos , Interleucina-8/metabolismo , Masculino , Persona de Mediana Edad , Reacción en Cadena de la Polimerasa , Pruebas de Función Respiratoria , Tomografía Computarizada por Rayos XRESUMEN
In human cancers, the co-operative role between cell-adhesion receptors and proteases capable of degrading matrix barriers remains poorly understood. We have previously reported that the epithelium-restricted integrin alpha(v)beta6 becomes highly expressed in colon cancer compared with normal mucosa and that heterologous expression of alpha(v)beta6 in colon cancer cells is associated with enhanced cell growth. Herein, we report that alpha(v)beta6 expression in colon cancer cells leads to a relative increase in secretion of the matrix metalloproteinase gelatinase B over its respective inhibitor and that this secretion parallels the level of cell-surface beta6 expression. The alpha(v)beta6-mediated gelatinase B secretion is associated with increased proteolysis of denatured collagen at the cell surface, and inactivation of gelatinase B in beta6-expressing tumour cells inhibits cell spreading and proliferation within 3-dimensional collagen matrices. Our findings suggest that alpha(v)beta6-mediated gelatinase B secretion is important in the progression of human colon cancer.
Asunto(s)
Antígenos de Neoplasias , Colagenasas/metabolismo , Neoplasias del Colon/enzimología , Neoplasias del Colon/metabolismo , Integrinas/fisiología , División Celular/efectos de los fármacos , Colágeno/metabolismo , Colagenasas/biosíntesis , Humanos , Integrinas/biosíntesis , Metaloproteinasa 9 de la Matriz , Inhibidores de Proteasas/farmacología , Inhibidor Tisular de Metaloproteinasa-1/metabolismo , Células Tumorales CultivadasRESUMEN
Hereditary nonpolyposis colorectal cancer (HNPCC) describes the condition of a disparate group of families that have in common a predisposition to colorectal cancer in the absence of a premalignant phenotype. The genetic basis of this disease has been linked to mutations in genes associated with DNA mismatch repair. A large proportion of families harbor changes in one of two genes, hMSH2 and hMLH1. Approximately 35% of families in which the diagnosis is based on the Amsterdam criteria do not appear to harbor mutations in DNA-mismatch-repair genes. In this report we present data from a large series of families with HNPCC and indicate that there are subtle differences between families that harbor germline changes in hMSH2 and families that harbor hMLH1 mutations. Furthermore, there are differences between the mutation-positive group (hMSH2 and hMLH1 combined) of families and the mutation-negative group of families. The major findings identified in this study focus primarily on the extracolonic disease profile observed between the mutation-positive families and the mutation-negative families. Breast cancer was not significantly overrepresented in the hMSH2 mutation-positive group but was overrepresented in the hMLH1 mutation-positive group and in the mutation-negative group. Prostate cancer was not overrepresented in the mutation-positive groups but was overrepresented in the mutation-negative group. In age at diagnosis of colorectal cancer, there was no difference between the hMSH2 mutation-positive group and the hMLH1 mutation-positive group, but there was a significant difference between these two groups and the mutation-negative group.
Asunto(s)
Neoplasias Colorrectales Hereditarias sin Poliposis/genética , Neoplasias Colorrectales Hereditarias sin Poliposis/patología , Mutación/genética , Adolescente , Adulto , Edad de Inicio , Anciano , Anciano de 80 o más Años , Secuencia de Aminoácidos , Secuencia de Bases , Niño , Neoplasias Colorrectales Hereditarias sin Poliposis/epidemiología , Análisis Mutacional de ADN , Exones/genética , Genotipo , Mutación de Línea Germinal/genética , Humanos , Intrones/genética , Persona de Mediana Edad , Datos de Secuencia Molecular , Mutagénesis/genética , Metástasis de la Neoplasia , FenotipoRESUMEN
Peutz-Jeghers syndrome (PJS) is a rare cancer predisposition, which is characterized by the presence of hamartomatous polyposis and mucocutaneous pigmentation. A significant proportion of both familial and sporadic forms of this disorder are associated with mutations in the STK11 (serine/threonine kinase 11)/LKB1 gene. In this report we present a series of Australian PJS cases, which suggest that mutations in the STK11 gene do not account for many families or patients without a family history. The most likely explanation is either the presence of another susceptibility gene or genetic mosaicism in the non-familial patients.
Asunto(s)
Síndrome de Peutz-Jeghers/genética , Proteínas Serina-Treonina Quinasas/genética , Quinasas de la Proteína-Quinasa Activada por el AMP , Australia , Mapeo Cromosómico , Análisis Mutacional de ADN , Femenino , Heterogeneidad Genética , Humanos , Masculino , Mutación , Análisis de SecuenciaRESUMEN
CD36 is a transmembrane glycoprotein expressed on the surface of a number of cell types. The analysis of CD36 from platelets using immunoblotting, gel filtration, and native PAGE indicated the presence of high molecular complexes exceeding the Mr of monomeric CD36. Experiments using transfected COS-7 cells revealed these complexes were homodimers and -multimers of CD36. The multimers could be dissociated by treatment with a reducing agent, indicating they were formed by intermolecular cysteine-bridging. Mutagenesis of the cDNA for CD36 implicated the cysteines in the extracellular domain of the molecule. The potential physiological roles of CD36 multimerisation are discussed.
Asunto(s)
Plaquetas/química , Antígenos CD36/química , Conformación Proteica , Animales , Biopolímeros , Antígenos CD36/sangre , Antígenos CD36/aislamiento & purificación , Antígenos CD36/metabolismo , Células COS , Cromatografía en Gel , Cisteína/química , Cisteína/metabolismo , Dimerización , Electroforesis en Gel Bidimensional , Electroforesis en Gel de Poliacrilamida , Técnica del Anticuerpo Fluorescente , Immunoblotting , Microscopía Fluorescente , Mutagénesis , Compuestos de Sulfhidrilo/farmacología , Radioisótopos de Azufre , TransfecciónRESUMEN
We have previously reported that human colon cancer cells secrete a factor(s) which induces elongation of colon fibroblasts in vitro. Isolation of this factor led to the identification of a 55kD protein with fibroblast stretching activity. Two internal amino acid sequences identified in this protein (YEI; GFQALGDAADI) share complete homology with tissue inhibitor of metalloproteinase (TIMP-1).