RESUMEN
Ly-49C is a member of the polymorphic family of murine NK cell inhibitory receptors. The 5E6 antibody that defines a subset of NK cells responsible for the rejection of parental H-2d bone marrow by F1 mice has been shown previously to react with Ly-49C. Here, the 5E6 antibody was found to detect two Ly-49C-related molecules in B6 mice. Two cDNA clones were isolated from B6 NK cells, one identical to previously reported Ly-49CB6 and the other a novel cDNA. The deduced amino acid sequence of the latter differs from that of Ly-49CBALB at only 4 residues, whereas the previously reported Ly-49CB6 differs at 22 residues. Flow cytometric analyses of COS cells transfected with the two cDNAs showed that the 5E6 antibody binds to both Ly-49 molecules, while another anti-Ly-49C antibody, 4LO3311, binds to the newly described Ly-49C but not the previously reported Ly-49CB6. Two-color flow cytometric analysis detected 5E6+4LO3311- as well as 5E6+4LO3311+ subsets of NK cells from B6, but not BALB/c, mice. The level of Ly-49C expression on B6 NK cells detected by the 4LO3311 antibody was substantially lower than that on BALB/c NK cells. Binding specificity of the novel Ly-49CB6 was indistinguishable from that of Ly-49CBALB, whereas no binding was detectable with previously reported Ly-49CB6. These results demonstrate that the newly described Ly-49CB6, not the previously reported Ly-49CB6, is the probable B6 allelic form of Ly-49C. The previously reported Ly-49CB6 must be encoded by a separate gene and should be renamed Ly-49I. The implication of these results with respect to the role of Ly-49C in hybrid resistance is discussed.
Asunto(s)
Células Asesinas Naturales/inmunología , Glicoproteínas de Membrana/biosíntesis , Glicoproteínas de Membrana/química , Secuencia de Aminoácidos , Animales , Antígenos Ly/biosíntesis , Secuencia de Bases , Células COS , Membrana Celular/inmunología , Cartilla de ADN , Citometría de Flujo , Lectinas Tipo C , Ratones , Ratones Endogámicos BALB C , Ratones Endogámicos C57BL , Datos de Secuencia Molecular , Reacción en Cadena de la Polimerasa , Receptores Similares a Lectina de Células NK , Proteínas Recombinantes/biosíntesis , Proteínas Recombinantes/química , Homología de Secuencia de Aminoácido , Especificidad de la Especie , TransfecciónRESUMEN
Natural killer (NK) cells represent an important first line of defense against viruses and malignancy [1]. NK cells express a variety of inhibitory and activating receptors that interact with classical major histocompatibility complex (MHC) class I molecules on potential target cells and determine the NK cell response [2-4]. Mouse NK receptors are encoded by the C-type lectin multigene family Ly49. However, in humans, a completely different family of receptors, the immunoglobulin-like killer inhibitory receptors (KIRs), performs the same function [2-4]. One Ly49-like gene, Ly49L, exists in humans but is incorrectly spliced and assumed to be nonfunctional [5, 6]. Mouse KIR-like genes have not been found, and evidence suggests that the primate KIRs amplified after rodents and primates diverged [7, 8]. Thus, two structurally dissimilar families, Ly49 and KIR, have evolved to play similar roles in mouse and human NK cells. This apparent example of functional convergent evolution raises several questions. It is unknown, for example, when the Ly49L gene became nonfunctional and if this event affected the functional evolution of the KIRs. The distribution of these gene families in different mammals is unstudied, and it is not known if any species uses both types of receptors. Here, we demonstrate that the Ly49L gene shows evidence of conservation in other mammals and that the human gene likely became nonfunctional 6-10 million years ago. Furthermore, we show that baboon lymphocytes express both full-length Ly49L transcripts and multiple KIR genes.
Asunto(s)
Antígenos Ly , Evolución Molecular , Células Asesinas Naturales/inmunología , Glicoproteínas de Membrana/genética , Receptores Inmunológicos/genética , Empalme Alternativo , Secuencia de Aminoácidos , Animales , Secuencia de Bases , ADN Complementario , Humanos , Lectinas Tipo C , Datos de Secuencia Molecular , Papio , Receptores KIR , Receptores Similares a Lectina de Células NK , Homología de Secuencia de Ácido NucleicoRESUMEN
Programmed cell death (PCD), important in normal animal physiology and disease, can be divided into at least two morphological subtypes, including type I, or apoptosis, and type II, or autophagic cell death. While many molecules involved in apoptosis have been discovered and studied intensively during the past decade, autophagic cell death is not well characterized molecularly. Here we report the first comprehensive identification of molecules associated with autophagic cell death during normal metazoan development in vivo. During Drosophila metamorphosis, the larval salivary glands undergo autophagic cell death regulated by a hormonally induced transcriptional cascade. To identify and analyze the genes expressed, we examined wild-type patterns of gene expression in three predeath stages of Drosophila salivary glands using serial analysis of gene expression (SAGE) [7]. 1244 transcripts, including genes involved in autophagy, defense response, cytoskeleton remodeling, noncaspase proteolysis, and apoptosis, were expressed differentially prior to salivary gland death. Mutant expression analysis indicated that several of these genes were regulated by E93, a gene required for salivary gland cell death. Our analyses strongly support both the emerging notion that there is overlap with respect to the molecules involved in autophagic cell death and apoptosis, and that there are important differences.
Asunto(s)
Apoptosis/genética , Autofagia/genética , Drosophila/genética , Perfilación de la Expresión Génica , Animales , Drosophila/citología , Glándulas Salivales/citología , Glándulas Salivales/metabolismo , Transducción de SeñalRESUMEN
Seven cases of lower respiratory tract infection due to Corynebacterium pseudodiphtheriticum are described. Lower respiratory tract infections with C. pseudodiphtheriticum in immunocompetent patients are usually associated with pre-existing chronic pulmonary disease, and are sometimes associated with endotracheal intubation. Antimicrobial susceptibility testing of these isolates showed uniform sensitivity to penicillin and variable results to erythromycin.
Asunto(s)
Infecciones por Corynebacterium/microbiología , Infecciones del Sistema Respiratorio/microbiología , Anciano , Anciano de 80 o más Años , Corynebacterium/efectos de los fármacos , Corynebacterium/aislamiento & purificación , Femenino , Humanos , Masculino , Pruebas de Sensibilidad Microbiana , Persona de Mediana EdadAsunto(s)
Brotes de Enfermedades , Neumonía por Mycoplasma/diagnóstico , Adolescente , Adulto , Niño , Preescolar , Pruebas de Fijación del Complemento , Humanos , Inmunoglobulina M/análisis , Neumonía por Mycoplasma/inmunología , Neumonía por Mycoplasma/transmisión , Refugiados , Estudios Retrospectivos , TailandiaRESUMEN
A strong regional program can be successful in either a single location or at multiple locations, but it cannot function properly if it is not well organized and staffed properly to deliver services. Extremely important elements to the success of an occupational health clinic that serves a wide geographical region are client retention, a strong information system to manage programs for multiple employers, and cutting-edge leadership that stays in the forefront and educates the business community on emerging issues in occupational health and safety.
Asunto(s)
Servicios de Salud del Trabajador/organización & administración , Sector Privado , Accidentes de Trabajo , Necesidades y Demandas de Servicios de Salud , Reestructuración Hospitalaria/organización & administración , Humanos , Medicina del Trabajo/organización & administración , Administración de Línea de Producción , Calidad de la Atención de Salud , Estados UnidosRESUMEN
The effects of ocean waves on lidar imaging of submerged objects are investigated. Two significant consequences of wave focusing or defocusing are quantified: (a) intensification of near-surface backscatter in which the mean return is increased relative to that for a flat interface, and (b) spatial-temporal modulations of the backscattered return. For the former, mean returns can be as much as 50% larger than flat surface returns at shallow depth. For the latter, the strong modulations induced by wave motion present a dominant clutter field that significantly affects the imaging of shallow objects. Both effects are compensated at greater depths by beam spreading caused by multiple scattering, which diminishes the intensity of the wave focusing.
RESUMEN
We have cloned several prototypic members of the family of human endogenous retroviruslike elements having a histidine tRNA primer-binding site (RTVL-H) and have determined the nucleotide sequence of one of these clones (RTVL-H2). The RTVL-H2 sequence is 5,813 nucleotides long, with long terminal repeats of 450 nucleotides. Although this particular sequence contains no long open reading frames, computer searches have revealed several segments of amino acid homology with known retroviral gene products. In the gag region of RTVL-H2, there is a segment with significant homology to a region of the gag protein p30 of type C baboon endogenous virus. In the pol region of RTVL-H2, three segments similar to the Moloney leukemia virus (MLV) pol polyprotein were detected. These correspond to parts of the protease, reverse transcriptase, and endonuclease domains of the MLV pol gene. Interestingly, the last two pol domains are equidistant in RTVL-H2 and the type C murine retroviruslike DNA sequence (MuRRS), both having deletions of equal sizes relative to the MLV pol gene. One other segment similar to a retroviral gene product was identified in the RTVL-H2 gag region. This segment has 55 to 60% amino acid homology to a 50-amino-acid region of the gag nucleic acid-binding proteins encoded by human T-cell lymphotropic viruses types I and II and bovine leukemia virus. Thus, the RTVL-H2 genome harbors sequences related to evolutionarily distant retroviruses.
Asunto(s)
Deltaretrovirus/genética , Genes Virales , Genes , Retroviridae/genética , Secuencia de Aminoácidos , Secuencia de Bases , ADN/genética , ADN Viral/genética , Endonucleasas/genética , Humanos , Datos de Secuencia Molecular , Péptido Hidrolasas/genética , ADN Polimerasa Dirigida por ARN/genética , Secuencias Repetitivas de Ácidos Nucleicos , Homología de Secuencia de Ácido Nucleico , Proteínas Virales/genéticaRESUMEN
The repetitive ETn (early transposon) family of sequences represents an active "mobile mutagen" in the mouse genome. The presence of long terminal repeats (LTRs) and other diagnostic features indicate that ETns are retrotransposons but they contain no long open reading frames or documented similarity to the genes of known retroviruses or other retroelements. Thus, the mechanisms responsible for the mobility of this family have been unknown. In this study, we used computer searches to detect a small region of previously unrecognized type D retroviral pol homology within ETn elements. This small region was used to isolate two mouse endogenous proviral elements with gag, pro, and pol genes similar to simian type D viruses. This new family of mouse endogenous proviruses, termed MusD, is present in several hundred copies in the genome. Interestingly, the MusD LTRs, 3' internal region, and the 5' region expected to contain the packaging signal are very closely related to members of the ETn subfamily that have recently transposed. Analysis of different mouse strains indicates that MusD elements predate the existence of the mobile subfamily of ETns. These findings indicate that the ETn family was likely created via recombination events resulting in a near complete substitution of MusD coding sequences with unrelated DNA. Furthermore, these results suggest that ETn transcripts retrotranspose using proteins provided by MusD proviruses.
Asunto(s)
Retrovirus Endógenos/genética , Provirus/genética , Retroelementos/genética , Secuencias Repetidas Terminales/genética , Secuencia de Aminoácidos , Animales , Secuencia de Bases , Genes gag/genética , Genes pol/genética , Genoma Viral , Virus del Mono Mason-Pfizer , Ratones , Datos de Secuencia Molecular , Análisis de Secuencia de ADNRESUMEN
The evolutionary origin and age of the HERV-H family of human endogenous retrovirus-like sequences was investigated in this study. HERV-H elements exist in approximately 900 partially deleted copies and 50-100 more intact forms in humans and Old World monkeys. However, their possible presence in more divergent species is unknown. We have isolated a 1.6-kb genomic DNA segment from the New World monkey marmoset that had been PCR amplified using human HERV-H primers. DNA and protein comparisons and database searches indicate that this marmoset clone is more closely related to human HERV-H elements than to any other sequence, indicating that HERV-H-related sequences do exist in New World monkeys. In contrast to the high copy numbers of deleted elements in Old World primates. Southern blot analysis shows that such elements are present in less than 50 copies in two different species of New World monkey. To estimate evolutionary ages of the common deleted form of the element, a selected DNA segment from the pol region was compared from multiple human HERV-H elements. This comparison suggests that many HERV-H elements of the abundant deleted subfamily integrated approximately 30-35 million years ago. Very similar percentage divergence values between 5' and 3' long terminal repeats of individual elements of the deleted subfamily also suggest that these elements are close in age. These results indicate that HERV-H elements first appeared in the germline prior to the New World/Old World divergence over 40 million years ago. Interestingly, they remained in low numbers in the New World branch while a subfamily underwent a major amplification in Old World primates before the time of divergence of hominoids from Old World monkeys.
Asunto(s)
Cebidae/genética , Cercopithecidae/genética , Evolución Molecular , Genoma Viral , Genoma , Retroviridae/genética , Animales , Aotidae/genética , Aotidae/virología , Secuencia de Bases , Callithrix/genética , Callithrix/virología , Cebidae/virología , Línea Celular , Línea Celular Transformada , Cercopithecidae/virología , Cartilla de ADN , Amplificación de Genes , Genes pol , Humanos , Datos de Secuencia Molecular , Filogenia , Secuencias Repetitivas de Ácidos Nucleicos , Homología de Secuencia de Aminoácido , Homología de Secuencia de Ácido NucleicoRESUMEN
We previously reported that a long terminal repeat (LTR) of a human endogenous retrovirus of the HERV-H family promotes expression of a cellular fusion transcript in teratocarcinoma cell lines. This transcript was termed PLA2L due to two regions of similarity to the secreted form of phospholipase A2. In this study, evidence is presented indicating that this transcript appears to be the result of intergenic splicing between the HERV-H element and two independent downstream genes. The 5' gene has been named HHLA1 (HERV-H LTR-associating 1) and is of unknown function but shows sequence conservation in other mammals. The 3' gene is now known to encode human otoconin-90 (OC90) which, in mice, is a major protein expressed in the fetal inner ear. Evidence for intergenic splicing of these two genes includes: (1) the isolation of LTR-driven HHLA1 transcripts, unspliced to otoconin-90 exons, with variable sites of polyadenylation; (2) the cloning of both the putative human intergenic genomic region and the novel 5' terminus of the mouse otoconin-90 gene; (3) the identification of homologous potential signal sequences in the 5' region of mouse otoconin-90 and in the middle of the PLA2L transcript; and (4) the lack of detectable chromosomal rearrangements involving this region in teratocarcinoma cells. The PLA2L transcript therefore represents a rare example of intergenic splicing of two closely linked genes. We hypothesize that human HHLA1 and OC90 are normally expressed independently from different promoters but are expressed from the LTR promoter and spliced together in teratocarcinoma cells. It is tempting to speculate that the high activity of the LTR promoter in this cell type may induce transcriptional fusion between these two genes.
Asunto(s)
Retrovirus Endógenos/genética , Genes Virales , Glicoproteínas/genética , Fosfolipasas A/genética , Empalme del ARN , Regiones no Traducidas 5' , Secuencia de Aminoácidos , Animales , Secuencia de Bases , Células COS , Proteínas de Unión al Calcio , Callithrix , Línea Celular , Clonación Molecular , Secuencia Conservada , ADN Complementario , Evolución Molecular , Proteínas de la Matriz Extracelular , Reordenamiento Génico , Fosfolipasas A2 Grupo II , Humanos , Ratones , Datos de Secuencia Molecular , Sistemas de Lectura Abierta , Fosfolipasas A2 , Translocación GenéticaRESUMEN
The effectiveness of a research program for minority high school students was evaluated. The program, supported by funding from the National Institutes of Health, was begun in 1982; during the subsequent five years, there were 59 applicants and 38 participants in the program. Of the responding 20 participants, 12 were pursuing careers in science and medicine, and half of the 16 respondents with career plans reported that the program had influenced their career decisions. Overall and in each year, black male students were underrepresented in both the applicant pool and the participants as compared with the metropolitan high school population.
Asunto(s)
Educación Médica , Becas , Grupos Minoritarios , Adolescente , Selección de Profesión , Estudios de Evaluación como Asunto , Femenino , Empleos en Salud , Humanos , Louisiana , Masculino , National Institutes of Health (U.S.) , Encuestas y Cuestionarios , Estados UnidosRESUMEN
HERV-H elements are a large family of endogenous retrovirus-like sequences found in approximately 1000 dispersed copies in the genomes of humans and other primates. The most abundant subclass of these elements is a partially deleted form of 5.8 kb which is transcribed primarily as a 5.6-kb unit length RNA and a 3.7-kb spliced derivative. The provirus-like structure of these elements suggests that their numbers have increased in the genome through retrotransposition. However, this has not been demonstrated for HERV-H. To determine if genomic expansion of HERV-H elements involved an RNA intermediate, primate DNAs were screened by PCR for elements that were transcribed, spliced, reverse transcribed, and integrated back into the genome. This PCR screen detected several genomic HERV-H fragments that appear to be derived from spliced transcripts. Interestingly, the presence of one of these fragments is polymorphic in humans, suggesting that its integration was a relatively recent event. Another PCR strategy was used to determine that at least one of the spliced elements has an intact 5' LTR, indicating that it is not simply a "processed pseudogene" or cDNA copy of a HERV-H transcript. Genomic cloning and sequencing of a human locus harboring a spliced element revealed the expected structure, e.g., intact LTRs and flanking 5-bp direct repeats, for a virally retrotransposed element. A genomic library screening method also indicated that very few HERV-H elements (less than 1%) have the structure of processed pseudogenes. These results suggest that most HERV-H elements amplified in the genome as viral retrotransposons.
Asunto(s)
ADN Viral/análisis , ADN/genética , Amplificación de Genes , Empalme del ARN , Retroviridae/genética , Integración Viral , Animales , Secuencia de Bases , Línea Celular , ADN Viral/genética , Humanos , Datos de Secuencia Molecular , Primates , Seudogenes , Retroelementos , Homología de Secuencia de Ácido NucleicoRESUMEN
Several families of repetitive sequences related to integrated retroviruses have been identified in the human genome. The largest of these families, the RTVL-H family, has close to 1000 members in addition to a similar number of solitary long terminal repeats (LTRs) dispersed on all chromosomes. Previous work has shown that the expression of genomic RTVL-H elements is driven by their LTRs and that some LTRs can promote expression of a reporter gene. These observations suggest that some endogenous RTVL-HLTRs may naturally regulate the transcription of adjacent cellular genes or that rearrangements involving these elements may cause aberrant gene expression. To investigate this possibility, we have used a differential screening strategy to identify chimeric cDNA clones derived from LTR-promoted transcripts. Here we report the identification and analysis of four such clones isolated from an NTera2D1 (teratocarcinoma) cDNA library. Two of the clones, AF-1 and AF-2, contain termination codons in all reading frames. Another clone, AF-4, contains LTR sequences linked in the genome to a CpG island. The fourth clone, AF-3, contains an 862-bp open reading frame representing part of a novel gene (CDC4L) with homology to the yeast cell division cycle gene CDC4. These findings indicate that RTVL-H elements may be involved in the regulation of diverse cellular transcripts in human cells.
Asunto(s)
Secuencias Repetitivas de Ácidos Nucleicos , Saccharomyces cerevisiae/genética , Transcripción Genética , Secuencia de Aminoácidos , Secuencia de Bases , Northern Blotting , Southern Blotting , ADN , Humanos , Datos de Secuencia Molecular , Homología de Secuencia de Ácido NucleicoRESUMEN
An analytical model for the beam spread function with time dispersion is modeled and validated against Monte Carlo calculations. The model, which is structured on simple statistical concepts and relies on only first and second moments for displacement, angle, and multipath time, is suitable for describing pulsed laser radiation propagation in nonconservative scattering media out to tens of scattering lengths. Numerical examples for marine environments are used to show its robustness and versatility.
RESUMEN
During the course of an investigation into the potential effects of endogenous retroviruses on adjacent gene expression, we isolated two cDNA clones containing a small sequence segment belonging to the human endogenous retrovirus family, HERV-H. Characterization of the clones revealed that they represent transcripts from a novel KRAB zinc finger gene termed ZNF177. The two cDNA clones differ at their 5' termini and in the presence of a 559-bp internal exon. The clone containing this internal exon has six imperfect zinc finger motifs followed by seven perfect copies of the C2H2 type but has a frame shift between the KRAB domain and the downstream zinc finger region. The smaller clone lacks the six imperfect motifs and has an intact ORF. The 5' putative untranslated regions of both cDNAs contain an 86-bp HERV-H env segment and a segment of an Alu repeat, both in the antisense orientation, that have been incorporated by splicing. RT-PCR experiments show evidence of alternative splicing but the majority of transcripts appear to contain the Alu and env segments. Genomic PCR and hybridization experiments suggest that a partial HERV-H element is integrated within the ZNF177 locus, which Southern analysis has shown to be a single-copy gene. Northern and RT-PCR analyses suggest that ZNF177 is transcribed at a low level in a variety of cell types.
Asunto(s)
Proteínas de Unión al ADN , Empalme del ARN , Secuencias Repetitivas de Ácidos Nucleicos , Retroviridae/genética , Transcripción Genética , Proteínas Virales/biosíntesis , Proteínas Virales/genética , Dedos de Zinc/genética , Secuencia de Aminoácidos , Secuencia de Bases , Clonación Molecular , Cartilla de ADN , Sondas de ADN , Biblioteca de Genes , Genes env , Humanos , Datos de Secuencia Molecular , Reacción en Cadena de la Polimerasa , Biosíntesis de Proteínas , Retroviridae/aislamiento & purificación , Homología de Secuencia de Aminoácido , Homología de Secuencia de Ácido Nucleico , Teratocarcinoma , Células Tumorales CultivadasRESUMEN
Ly-49 (YE1/48, A1) is a dimer protein expressed on subpopulations of murine NK cells. It is a member of a superfamily of type II transmembrane proteins containing carbohydrate recognition domains (CRD). In the mouse genome, the detection of multiple restriction fragments that cross-hybridize with Ly-49 cDNA probes suggests the presence of related genes. In this study, we have isolated several genomic clones encoding portions of CRD sequences highly homologous to the CRD of Ly-49. By using primers based on the consensus sequences of the genomic clones, expression of Ly-49-related genes was detected by the polymerase chain reaction in various organs, including lung, kidney, liver, spleen, and thymus. Two full-length cDNA clones that are highly homologous to the Ly-49 gene were subsequently isolated from a lung cDNA library. At the nucleotide level, the two clones are 72% and 80% identical to Ly-49 in their translated regions, but their sequences are different from those of the genomic clones characterized to date. The two cDNA clones potentially encode type II transmembrane proteins containing CRD that are very similar to Ly-49. These amino acid sequences are also homologous to other members of the superfamily of CRD-containing type II transmembrane proteins, including hepatic lectins and the low affinity IgER (CD23). The homology is most evident in the CRD but is also significant in other domains. These results demonstrate the existence of several functional genes that are highly related to Ly-49. These genes comprise a subfamily within the superfamily of type II transmembrane proteins containing CRD.
Asunto(s)
Antígenos Ly/genética , Células Asesinas Naturales/química , Proteínas de la Membrana/genética , Familia de Multigenes , Secuencia de Aminoácidos , Animales , Antígenos Ly/fisiología , Secuencia de Bases , Northern Blotting , Metabolismo de los Hidratos de Carbono , Clonación Molecular , ADN/aislamiento & purificación , Ratones , Datos de Secuencia Molecular , Reacción en Cadena de la PolimerasaRESUMEN
In a previous study, we isolated a novel human cDNA with two domains of homology to secreted phospholipase A2 (sPLA2) embedded within a much larger open reading frame. The corresponding gene, termed PLA2L, is also unusual in that it is transcribed from an endogenous retroviral long terminal repeat promoter in teratocarcinoma cell lines. The associated retroviral element, a member of the HERV-H family of sequences, is found within an intron of the human PLA2L gene and has apparently assumed transcriptional regulatory functions at this locus. In this study we have isolated genomic clones spanning the human PLA2L locus and have determined the intron/exon structure of the PLA2-like domains. This intron/exon structure is very similar to that of known sPLA2s despite the fact that the PLA2L gene is highly diverged and has a novel duplicated structure. We also mapped PLA2L to chromosome 8q24, a location that differs from the known locations of human sPLA2s. Genomic PCR across primate species was performed to determine the approximate time of integration of the HERV-H element. Results indicate that the element integrated 15-20 million years ago since it is present in chimpanzee and gorilla but absent in orangutan and lower primates. Although the function of the PLA2L gene is not known, genomic Southern analyses suggest evolutionary conservation in mammals. These results contribute to our understanding of the unique and complex evolutionary history of the PLA2L gene.
Asunto(s)
Evolución Molecular , Exones , Intrones , Fosfolipasas A/genética , Secuencia de Aminoácidos , Animales , Mapeo Cromosómico , Cromosomas Humanos Par 8 , Clonación Molecular , Secuencia Conservada , Regulación de la Expresión Génica , Fosfolipasas A2 Grupo II , Humanos , Datos de Secuencia Molecular , Fosfolipasas A2 , Mapeo Restrictivo , Retroviridae/genética , Homología de Secuencia de AminoácidoRESUMEN
Despite numerous studies on the function of Ly49 natural killer cell receptors in the mouse, relatively little is known about how these genes are regulated at the transcriptional level. In the present study, we sequenced and compared 800 bp of the promoter region of nine Ly49 genes from C57B1/6 mice. This comparison showed that there is a high degree of sequence identity between the genes, and also revealed a region which is conserved between the mouse genes and the human Ly49L gene, indicating a potential core promoter region. This analysis also found that Ly49B and H differ from the other genes in having long interspersed repetitive sequence in their promoter region which suggests a gene conversion or rearrangement involving these two genes. In addition, we performed 5' rapid amplification of cDNA ends on four Ly49 genes to localize transcriptional start sites. These experiments showed that the transcriptional initiation sites are heterogeneous for all of the genes examined, and that a large majority of Ly49G transcripts originate from the second exon as well as its first intron. Although potential TATA boxes have been previously identified for some of the genes, we did not find evidence that a majority of transcripts initiate at the expected distance downstream of these boxes. Our data suggest that differences in the location of transcriptional start sites contribute to the observed complexity in receptor repertoire patterns.