RESUMEN
We examined the long arm XY pseudoautosomal region for linkage to asthma, serum IgE, and bronchial hyperresponsiveness. In 57 Caucasian families multipoint nonparametric analyses provide evidence for linkage between DXYS154 and bronchial hyperresponsiveness (P = 0.000057) or asthma (P = 0.00065). This genomic region is approximately 320 kb in size and contains the interleukin-9 receptor gene. These results suggest that a gene controlling asthma and bronchial hyperresponsiveness maybe located in this region and that the interleukin-9 receptor is a potential candidate.
Asunto(s)
Asma/genética , Hiperreactividad Bronquial/genética , Cromosoma X/genética , Cromosoma Y/genética , Mapeo Cromosómico , Familia , Femenino , Ligamiento Genético , Humanos , Inmunoglobulina E/genética , Escala de Lod , Masculino , Repeticiones de Microsatélite , Receptores de Interleucina/genéticaRESUMEN
Genetic studies on mouse models of asthma have identified interleukin-9 (IL9) as a determining factor in controlling bronchial hyperresponsiveness, a hallmark of the disease. Recently, the human IL9 receptor (hIL9R) gene locus has also been implicated in determining susceptibility to bronchial hyperresponsiveness and asthma. In order to evaluate the structure and function of the encoded product, we analyzed receptor transcripts derived from peripheral blood mononuclear cells of 50 unrelated donors. Sequence analysis of the entire coding region identified a splice variant that contains an in frame deletion of a single residue at codon 173 (DeltaQ). This variant could be permanently expressed in a cytokine-dependent murine T-cell line but lacked the ability to induce proliferation in response to human IL9. In situ analyses of cells expressing the wild-type and DeltaQ receptors found both forms to be expressed at the cell surface, but the DeltaQ receptor was unable to bind hIL9 and could not be recognized by N-terminal specific antibodies. These findings demonstrate that hIL9RDeltaQ presents an altered structure and function and suggests its potential role in down-regulating IL9 signaling in effector cells and associated biological processes.
Asunto(s)
Empalme Alternativo , Variación Genética , Interleucina-9/fisiología , Activación de Linfocitos , Linfocitos/inmunología , Receptores de Interleucina/genética , Transcripción Genética , Secuencia de Aminoácidos , Animales , Células COS , Clonación Molecular , Codón , Citometría de Flujo , Humanos , Interleucina-9/farmacología , Ratones , Reacción en Cadena de la Polimerasa , Receptores de Interleucina/química , Receptores de Interleucina/fisiología , Receptores de Interleucina-9 , Proteínas Recombinantes/biosíntesis , Eliminación de Secuencia , Transducción de Señal , Linfocitos T/inmunología , TransfecciónRESUMEN
Asthma is a complex heritable inflammatory disorder of the airways associated with clinical signs of atopy and bronchial hyperresponsiveness. Recent studies localized a major gene for asthma to chromosome 5q31-q33 in humans. Thus, this segment of the genome represents a candidate region for genes that determine susceptibility to bronchial hyperresponsiveness and atopy in animal models. Homologs of candidate genes on human chromosome 5q31-q33 are found in four regions in the mouse genome, two on chromosome 18, and one each on chromosomes 11 and 13. We assessed bronchial responsiveness as a quantitative trait in mice and found it linked to chromosome 13. Interleukin 9 (IL-9) is located in the linked region and was analyzed as a gene candidate. The expression of IL-9 was markedly reduced in bronchial hyporesponsive mice, and the level of expression was determined by sequences within the qualitative trait locus (QTL). These data suggest a role for IL-9 in the complex pathogenesis of bronchial hyperresponsiveness as a risk factor for asthma.
Asunto(s)
Asma/genética , Interleucina-9/genética , Animales , Células Cultivadas , Mapeo Cromosómico , Femenino , Regulación de la Expresión Génica , Ligamiento Genético , Interleucina-9/metabolismo , Pulmón/metabolismo , Masculino , Ratones , Ratones Endogámicos , Fenotipo , Carácter Cuantitativo Heredable , ARN Mensajero/genética , ARN Mensajero/metabolismo , Especificidad de la Especie , Bazo/citología , Bazo/metabolismoRESUMEN
We have used clones of 17 single-copy human DNA sequences to analyze their counterparts in the genome of the domestic dog by heterologous hybridization. Ten of the 17 sequences represented anchor loci proposed for comparative mammalian mapping. Eight of 17 human clones (including three of the anchor loci) gave clear hybridization signals when used with Southern blots of canine DNA. Five of these eight (including two anchor loci) showed diallelic restriction fragment length polymorphisms in a large kindred of Brittany spaniels and could be used for segregation studies. Several probes chosen from different human chromosomes also were unlinked in the dog. By contrast, linkage was found between the canine counterparts of the closely linked human serum amyloid A gene family. Three markers linked on human chromosome II appeared not to be syntenic in the dog. DNA markers linked to various human genetic neuromuscular diseases were not linked to hereditary canine spinal muscular atrophy which segregates in this kindred. However, there was evidence of possible linkage of this disorder with a canine counterpart of the tyrosinase gene. Segregation studies using heterologous single-copy DNA probes can be performed in dogs, but the level of inbreeding may reduce heterogeneity and limit the power of the analysis.