RESUMEN
Unprecedented advances in genomics, data science, and biotechnology have ushered in a new era of health care in which interventions are increasingly tailored to individual patients. Precision-based approaches extend to oral health, which is essential to overall health. Harnessing the full potential of precision oral health will depend on research to more fully understand the factors that underlie health and contribute to disease-including the human genome, microbiome, epigenome, proteome, and others.
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Salud Bucal , Medicina de Precisión , Genoma Humano , Genómica , Humanos , ProteomaRESUMEN
Despite impressive worldwide improvements in oral health, inequalities in oral health status among and within countries remain a daunting public health challenge. Oral health inequalities arise from a complex web of health determinants, including social, behavioral, economic, genetic, environmental, and health system factors. Eliminating these inequalities cannot be accomplished in isolation of oral health from overall health, or without recognizing that oral health is influenced at multiple individual, family, community, and health systems levels. For several reasons, this is an opportune time for global efforts targeted at reducing oral health inequalities. Global health is increasingly viewed not just as a humanitarian obligation, but also as a vehicle for health diplomacy and part of the broader mission to reduce poverty, build stronger economies, and strengthen global security. Despite the global economic recession, there are trends that portend well for support of global health efforts: increased globalization of research and development, growing investment from private philanthropy, an absolute growth of spending in research and innovation, and an enhanced interest in global health among young people. More systematic and far-reaching efforts will be required to address oral health inequalities through the engagement of oral health funders and sponsors of research, with partners from multiple public and private sectors. The oral health community must be "at the table" with other health disciplines and create opportunities for eliminating inequalities through collaborations that can harness both the intellectual and financial resources of multiple sectors and institutions.
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Investigación Dental/economía , Salud Global , Investigación sobre Servicios de Salud/economía , Disparidades en el Estado de Salud , Salud Bucal , Apoyo a la Investigación como Asunto , Recesión Económica , Política de Salud/economía , Prioridades en Salud/economía , Humanos , Cooperación Internacional , Salud Pública/economía , Asociación entre el Sector Público-Privado , Factores SocioeconómicosAsunto(s)
Interacciones Huésped-Patógeno , Interacciones Microbianas , Boca/microbiología , Genómica , HumanosRESUMEN
Epidemiological characteristics of sarcoidosis differ according to geographical distribution. The aim of our study was to disclose epidemiological characteristics in our country. The data was collected from investigators, who sent information on newly-diagnosed patients via internet. In 2 years 198 female and 95 male patients were enrolled to the study (f/m:2.08). Mean age of patients was 44+/-13 years (17-90). Mean age of male patients was 38+/-12 while mean age of female patients was 48+/-13 (p<0.001). 73.4% of patients were nonsmokers (85.4% of females; 48.4% of males; (p<0.001)). About 50% of our 293 patients were housewives. Familial sarcoidosis was found in 3 patients' first degree relatives. Estimated annual incidence of sarcoidosis for Turkey was calculated as 4 per 100,000 person. According to our study, 2/3 of sarcoidosis patients were women; mean age of patients was 45 and the disease began 10 years later in female patients. 80% of patients were nonsmokers; negative relation between sarcoidosis and smoking was evident especially in women. Familial sarcoidosis frequency was lower compared to other studies in the literature. There was no occupational exposure history in our patients. Our incidence rate, is similar with the results of other European studies.
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Sarcoidosis Pulmonar/epidemiología , Adolescente , Adulto , Anciano , Anciano de 80 o más Años , Métodos Epidemiológicos , Femenino , Humanos , Masculino , Tamizaje Masivo , Persona de Mediana Edad , Sarcoidosis Pulmonar/diagnóstico , Fumar/epidemiología , Turquía/epidemiología , Adulto JovenRESUMEN
O-Glycan biosynthesis is initiated by the transfer of N-acetylgalactosamine (GalNAc) from a nucleotide sugar donor (UDP-GalNAc) to Ser/Thr residues of an acceptor substrate. The detailed transfer mechanism, catalyzed by the UDP-GalNAc polypeptide:N-acetyl-alpha-galactosaminyltransferases (ppGalNAcTs), remains unclear despite structural information available for several isoforms in complex with substrates at various stages along the catalytic pathway. We used all-atom molecular dynamics simulations with explicit solvent and counterions to study the conformational dynamics of ppGalNAcT-2 in several enzymatic states along the catalytic pathway. ppGalNAcT-2 is simulated both in the presence and in the absence of substrates and reaction products to examine the role of conformational changes in ligand binding. In multiple 40-ns-long simulations of more than 600 ns total run time, we studied systems ranging from 45,000 to 95,000 atoms. Our simulations accurately identified dynamically active regions of the protein, as previously revealed by the X-ray structures, and permitted a detailed, atomistic description of the conformational changes of loops near the active site and the characterization of the ensemble of structures adopted by the transferase complex on the transition pathway between the ligand-bound and ligand-free states. In particular, the conformational transition of a functional loop adjacent to the active site from closed (active) to open (inactive) is correlated with the rotameric state of the conserved residue W331. Analysis of water dynamics in the active site revealed that internal water molecules have an important role in enhancing the enzyme flexibility. We also found evidence that charged side chains in the active site rearrange during site opening to facilitate ligand binding. Our results are consistent with the single-displacement transfer mechanism previously proposed for ppGalNAcTs based on X-ray structures and mutagenesis data and provide new evidence for possible functional roles of certain amino acids conserved across several isoforms.
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N-Acetilgalactosaminiltransferasas/química , Uridina Difosfato N-Acetilgalactosamina/química , Sitios de Unión , Cristalografía por Rayos X , Cinética , Ligandos , Manganeso/química , Manganeso/metabolismo , Modelos Moleculares , N-Acetilgalactosaminiltransferasas/metabolismo , Conformación Proteica , Relación Estructura-Actividad , Uridina Difosfato N-Acetilgalactosamina/metabolismo , Agua/química , Agua/metabolismoRESUMEN
Thoracic endometriosis is an uncommon disorder. In most cases, the diagnosis is based on history alone and radiographic findings depend on the menstrual cycle. CT findings include ill-defined or well-defined opacities, nodular lesions, cavities, cystic changes and bullous formation. We report a case of pulmonary parenchymal endometriosis with an unusual radiographic finding.
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Endometriosis/diagnóstico por imagen , Enfermedades Pulmonares/diagnóstico por imagen , Enfermedades Torácicas/diagnóstico por imagen , Adulto , Femenino , Humanos , Pulmón/diagnóstico por imagen , Tomografía Computarizada por Rayos X , UltrasonografíaAsunto(s)
Política de Salud , Programas Nacionales de Salud , Salud Bucal , Sector Privado , Humanos , Estados UnidosRESUMEN
BACKGROUND: Since the clinical features of sarcoidosis and tuberculosis may mimic each other, and that differentiation is not easy on clinical grounds, a histologic diagnosis may be mandatory in countries where the prevalence of tuberculosis is high or in populations with large numbers of immigrants from those countries. Previous studies have suggested the minor salivary gland biopsy as a useful method in the diagnosis of sarcoidosis. The present study was undertaken to evaluate the value of labial biopsy in the differentiation of sarcoidosis from tuberculosis in patients with enlarged hilar and paratracheal lymph nodes. METHODS: Labial biopsy was performed in 50 consecutive patients with sarcoidosis, and in 35 consecutive patients with tuberculosis who had intrathoracic lympadenopathy. The files of all patients were reviewed for the clinical presentation, radiographic features, SACE levels, tuberculin skin test anergy, and the frequency of positive labial biopsy in each disease. RESULTS: Noncaseating granulomas were present in labial biopsies obtained from 24 patients (48%) of 50 patients with sarcoidosis. Labial biopsies were positive in 4 of 6 patients who had an abnormality on eye examination and in 3 of 5 patients who had noncaseating granulomas on biopsy material from skin. In two of 4 patients who underwent mediastinoscopy, noncaseating granulomas were detected on labial biopsy. In contrast to the patients with sarcoidosis labial biopsies revealed normal minor salivary glands in all patients with tuberculosis. CONCLUSIONS: Labial biopsy has a high discriminatory value as a diagnostic tool in the differentiation of sarcoidosis from tuberculosis. Although it has a rather lower diagnostic yield than transbronchial lung biopsy, labial biopsy should be considered as a first line approach prior to performing other more invasive procedures for the tissue confirmation of sarcoidosis.
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Labio/patología , Sarcoidosis/diagnóstico , Tuberculosis Pulmonar/diagnóstico , Adolescente , Adulto , Biopsia , Diagnóstico Diferencial , Femenino , Humanos , Masculino , Persona de Mediana Edad , Sarcoidosis/patología , Tuberculosis Pulmonar/patologíaRESUMEN
We have cloned, expressed and characterized the gene encoding a ninth member of the mammalian UDP-GalNAc:polypeptide N-acetylgalactosaminyltransferase (ppGaNTase) family, termed ppGaNTase-T9. This type II membrane protein consists of a 9-amino acid N-terminal cytoplasmic region, a 20-amino acid hydrophobic/transmembrane region, a 94-amino acid stem region, and a 480-amino acid conserved region. Northern blot analysis revealed that the gene encoding this enzyme is expressed in a broadly distributed manner across many adult tissues. Significant levels of 5- and 4.2-kilobase transcripts were found in rat sublingual gland, testis, small intestine, colon, and ovary, with lesser amounts in heart, brain, spleen, lung, stomach, cervix, and uterus. In situ hybridization to mouse embryos (embryonic day 14.5) revealed significant hybridization in the developing mandible, maxilla, intestine, and mesencephalic ventricle. Constructs expressing this gene transiently in COS7 cells resulted in no detectable transferase activity in vitro against a panel of unmodified peptides, including MUC5AC (GTTPSPVPTTSTTSAP) and EA2 (PTTDSTTPAPTTK). However, when incubated with MUC5AC and EA2 glycopeptides (obtained by the prior action of ppGaNTase-T1), additional incorporation of GalNAc was achieved, resulting in new hydroxyamino acid modification. The activity of this glycopeptide transferase is distinguished from that of ppGaNTase-T7 in that it forms a tetra-glycopeptide species from the MUC5AC tri-glycopeptide substrate, whereas ppGaNTase-T7 forms a hexa-glycopeptide species. This isoform thus represents the second example of a glycopeptide transferase and is distinct from the previously identified form in enzymatic activity as well as expression in embryonic and adult tissues. These findings lend further support to the existence of a hierarchical network of differential enzymatic activity within the diversely regulated ppGaNTase family, which may play a role in the various processes governing development.
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N-Acetilgalactosaminiltransferasas/genética , N-Acetilgalactosaminiltransferasas/metabolismo , Transcripción Genética , Secuencia de Aminoácidos , Animales , Secuencia de Bases , Células COS , Clonación Molecular , Secuencia Conservada , Embrión de Mamíferos , Femenino , Regulación Enzimológica de la Expresión Génica , Glicopéptidos/metabolismo , Intestinos/enzimología , Masculino , Mamíferos , Ratones , Datos de Secuencia Molecular , N-Acetilgalactosaminiltransferasas/química , Especificidad de Órganos , Ovario/enzimología , Péptidos/química , Péptidos/metabolismo , Ratas , Proteínas Recombinantes/metabolismo , Ricina/química , Glándula Sublingual/enzimología , Especificidad por Sustrato , Testículo/enzimología , TransfecciónRESUMEN
Since the early 1900s, saliva has proven to be a noninvasive medium from which to measure a wide range of hormones, pharmaceuticals, and antibodies. It has also proven to be a convenient source of host and microbial DNA. As we enter the era of genomic medicine, increasing use of salivary diagnostics will help catalyze a shift from disease diagnosis to health surveillance. However, with the advances in this technology comes the additional obligation to ensure the privacy and rights of patients.
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Enfermedades de la Boca/diagnóstico , Saliva/química , Anticuerpos/análisis , Confidencialidad , ADN/análisis , ADN Bacteriano/análisis , Diagnóstico , Hormonas/análisis , Humanos , Salud Bucal , Derechos del Paciente , Saliva/inmunologíaRESUMEN
To address whether there are associations between the peptide composition of human parotid saliva and dental decay (caries) experience, we have characterized the peptides from parotid ductal saliva collected from nine adults who have remained free from dental caries (mean age = 59.2; Decayed Missing Filled Surfaces index [DMFS] = 0) and nine individuals who have experienced caries (mean age = 51.2; mean DMFS = 38.4). Ethanol-soluble peptides were size-fractionated on columns of Bio-Gel P-2; the salivary peptides derived from caries-susceptible subjects appeared larger than those found in the saliva of caries-free subjects. Peptides were then resolved into 19 species by cation exchange HPLC. Sequence analysis identified 18 peptides that appear to be proteolytic cleavage products of the basic proline-rich proteins IB-4, IB-5, IB-7, IB-8b, and P-B. The peptides that were more abundant in saliva obtained from the caries-free group differed from those isolated from the caries-susceptible group. The median peptide concentration of one possible precursor protein, IB-7, was found to be higher in saliva collected from caries-free individuals than in that from caries-susceptible individuals. Although differences were found in the phenotypes of proline-rich proteins expressed by these groups of caries-free and caries-susceptible subjects, no statistically significant associations were observed among proline-rich phenotypes and the level of any peptide. Collectively, our results indicate that proteolytic processing of parotid salivary proteins differs among individuals who have remained caries-free and those who have experienced dental decay.
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Caries Dental/complicaciones , Glándula Parótida/metabolismo , Péptidos/análisis , Prolina/análisis , Proteínas y Péptidos Salivales/análisis , Estudios de Casos y Controles , Cromatografía Líquida de Alta Presión , Índice CPO , Susceptibilidad a Caries Dentarias , Electroforesis en Gel de Poliacrilamida , Etanol , Femenino , Geles , Humanos , Immunoblotting , Masculino , Persona de Mediana Edad , Péptidos/genética , Fenotipo , Prolina/genética , Dominios Proteicos Ricos en Prolina , Precursores de Proteínas/análisis , Conductos Salivales/metabolismo , Proteínas y Péptidos Salivales/genética , SolventesRESUMEN
Cell migration and adhesion during embryonic development are complex processes which likely involve interactions among cell-surface carbohydrates. While considerable work has implicated proteoglycans in a wide range of developmental events, only limited attention has been directed towards understanding the 7role(s) played by the related class of mucin-type O-glycans. The initial step of mammalian mucin-type O-glycosylation is catalyzed by a family of UDP-GalNAc:polypeptide N-acetylgalactosaminyltransferases (ppGaNTases). The spatial expression patterns of the messenger RNAs of seven ppGaNTase family members were investigated from gastrulation through organogenesis stages of mouse development. The seven glycosyltransferases were expressed in unique patterns during embryogenesis. ppGaNTase-T1, -T2, -T4, and -T9 were expressed more ubiquitously than ppGaNTase-T3, -T5, and -T7. Organ systems with discrete accumulation patterns of ppGaNTase family members include the gastrointestinal tract (intestine, liver, stomach, submandibular gland), nervous system (brain, eye), lung, bone, yolk sac, and developing craniofacial region. The pattern in the craniofacial region included differential expression by family members in developing mandible, teeth, tongue and discrete regions of the brain including the pons and migratory, differentiating neurons. Additionally, ppGaNTase-T5 accumulates in a subset of mesenchymal cells at the ventral-most portions of the E12.5 maxilla and mandible underlying the dental lamina. The unique spatiotemporal expression of the different ppGaNTase family members during development suggests unique roles for each of these gene products.
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Regulación del Desarrollo de la Expresión Génica , Regulación Enzimológica de la Expresión Génica , N-Acetilgalactosaminiltransferasas/genética , ARN Mensajero/genética , Animales , Secuencia de Bases , Cartilla de ADN , Hibridación in Situ , RatonesRESUMEN
We report the cloning, expression, and characterization of a novel member of the mammalian UDP-GalNAc:polypeptide N-acetylgalactosaminyltransferase (ppGaNTase) family that transfers GalNAc to a GalNAc-containing glycopeptide. Northern blot analysis revealed that the gene encoding this enzyme, termed ppGaNTase-T6, is expressed in a highly tissue-specific manner. Significant levels of transcript were found in rat and mouse sublingual gland, stomach, small intestine, and colon; trace amounts were seen in the ovary, cervix, and uterus. Recombinant constructs were expressed transiently in COS7 cells but demonstrated no transferase activity in vitro against a panel of unmodified peptides, including GTTPSPVPTTSTTSAP (MUC5AC). However, when incubated with the total glycosylated products obtained by action of ppGaNTase-T1 on MUC5AC (mainly GTT(GalNAc)PSPVPTTSTT(GalNAc)SAP), additional incorporation of GalNAc was achieved, resulting in new hydroxyamino acids being modified. The MUC5AC glycopeptide failed to serve as a substrate for ppGaNTase-T6 after modification of the GalNAc residues by periodate oxidation and sodium borohydride reduction, indicating a requirement for the presence of intact GalNAc. This suggests that O-glycosylation of multisite substrates may proceed in a specific hierarchical manner and underscores the potential complexity of the processes that regulate O-glycosylation.
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N-Acetilgalactosaminiltransferasas/metabolismo , Péptidos/metabolismo , Secuencia de Aminoácidos , Animales , Secuencia de Bases , Clonación Molecular , Secuencia de Consenso , Secuencia Conservada , Humanos , Isoenzimas/química , Isoenzimas/genética , Isoenzimas/metabolismo , Ratones , Datos de Secuencia Molecular , N-Acetilgalactosaminiltransferasas/química , N-Acetilgalactosaminiltransferasas/genética , Especificidad de Órganos , Péptidos/química , Ratas , Proteínas Recombinantes/metabolismo , Alineación de Secuencia , Homología de Secuencia de Aminoácido , Especificidad por Sustrato , Polipéptido N-AcetilgalactosaminiltransferasaRESUMEN
Mucin-type O-glycosylation is initiated by a family of UDP-GalNAc:polypeptide N-acetylgalactosaminyltransferases (ppGaNTases). Based on sequence relationships with divergent proteins, the ppGaNTases can be subdivided into three putative domains: each putative domain contains a characteristic sequence motif. The 112-amino acid glycosyltransferase 1 (GT1) motif represents the first half of the catalytic unit and contains a short aspartate-any residue-histidine (DXH) or aspartate-any residue-aspartate (DXD)-like sequence. Secondary structure predictions and structural threading suggest that the GT1 motif forms a 5-stranded parallel beta-sheet flanked by 4 alpha-helices, which resembles the first domain of the lactose repressor. Four invariant carboxylates and a histidine residue are predicted to lie at the C-terminal end of three beta-strands and line the active site cleft. Site-directed mutagenesis of murine ppGaNTase-T1 reveals that conservative mutations at these 5 positions result in products with no detectable enzyme activity (D156Q, D209N, and H211D) or <1% activity (E127Q and E213Q). The second half of the catalytic unit contains a DXXXXXWGGENXE motif (positions 310-322) which is also found in beta1,4-galactosyltransferases (termed the Gal/GalNAc-T motif). Mutants of carboxylates within this motif express either no detectable activity, 1% or 2% activity (E319Q, E322Q, and D310N, respectively). Mutagenesis of highly conserved (but not invariant) carboxylates produces only modest alterations in enzyme activity. Mutations in the C-terminal 128-amino acid ricin-like lectin motif do not alter the enzyme's catalytic properties.
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N-Acetilgalactosaminiltransferasas/química , Conformación Proteica , Secuencia de Aminoácidos , Animales , Humanos , Lactosa , Ratones , Datos de Secuencia Molecular , Mutagénesis Sitio-Dirigida , N-Acetilgalactosaminiltransferasas/genética , N-Acetilgalactosaminiltransferasas/metabolismo , Análisis de Secuencia , Relación Estructura-ActividadRESUMEN
We report the cloning and expression of the fifth member of the mammalian UDP-GalNAc:polypeptide N-acetylgalactosaminyltransferase (ppGaNTase) family. Degenerate polymerase chain reaction amplification and hybridization screening of a rat sublingual gland (RSLG) cDNA library were used to identify a novel isoform termed ppGaNTase-T5. Conceptual translation of the cDNA reveals a uniquely long stem region not observed for other members of this enzyme family. Recombinant proteins expressed transiently in COS7 cells displayed transferase activity in vitro. Relative activity and substrate preferences of ppGaNTase-T5 were compared with previously identified isoforms (ppGaNTase-T1, -T3, and -T4); ppGaNTase-T5 and -T4 glycosylated a restricted subset of peptides whereas ppGaNTase-T1 and -T3 glycosylated a broader range of substrates. Northern blot analysis revealed that ppGaNTase-T5 is expressed in a highly tissue-specific manner; abundant expression was seen in the RSLG, with lesser amounts of message in the stomach, small intestine, and colon. Therefore, the pattern of expression of ppGaNTase-T5 is the most restricted of all isoforms examined thus far. The identification of this novel isoform underscores the diversity and complexity of the family of genes controlling O-linked glycosylation.
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Isoenzimas/genética , N-Acetilgalactosaminiltransferasas/genética , Secuencia de Aminoácidos , Animales , Secuencia de Bases , Clonación Molecular , Secuencia Conservada , ADN Complementario/genética , Biblioteca de Genes , Glicosilación , Isoenzimas/biosíntesis , Datos de Secuencia Molecular , Familia de Multigenes , N-Acetilgalactosaminiltransferasas/biosíntesis , Procesamiento Proteico-Postraduccional , Ratas , Proteínas Recombinantes/biosíntesis , Análisis de Secuencia de ADN , Homología de Secuencia de Aminoácido , Glándula Sublingual/enzimología , Distribución Tisular , Polipéptido N-AcetilgalactosaminiltransferasaRESUMEN
BACKGROUND: In this study, renal transplant recipients with tuberculosis of different organs, were retrospectively analysed with respect to prevalence, outcome and drug toxicity. PATIENTS AND METHODS: In 520 patients, 22 (4.2%) tuberculosis of various organs was diagnosed. The time interval between transplantation and diagnosis of tuberculosis was 44.4 +/- 33.5 (range 3-111) months. In 18 (82%) of the patients, tuberculosis was detected after the first year of transplantation. The most common form was pleuro/pulmonary tuberculosis (54%), and other localizations included jejunum, liver, bone, and urogenital tract. RESULTS: Sixteen of the 22 patients responded favourably to the treatment and maintain excellent allograft function, whereas six patients (27.2%) died. Toxic hepatitis was seen in four (18%) patients, and one case was complicated with acute hepatocellular failure due to isoniazide (INH). However, of the 23 patients at risk of tuberculosis who had had INH prophylaxis for 1 year, neither tuberculosis, nor hepatotoxicity was observed. CONCLUSION: Tuberculosis is a common infection of renal transplant recipients in developing countries. The peak incidence is after the first year of transplantation and mortality is considerable. Hepatoxicity is a considerable risk of treatment, possibly as a result of additive toxic effects of immunosuppressive drugs.
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Trasplante de Riñón/efectos adversos , Tuberculosis/etiología , Adulto , Antituberculosos/efectos adversos , Antituberculosos/uso terapéutico , Enfermedad Hepática Inducida por Sustancias y Drogas/etiología , Femenino , Humanos , Isoniazida/efectos adversos , Isoniazida/uso terapéutico , Masculino , Pronóstico , Estudios Retrospectivos , Tuberculosis/diagnóstico , Tuberculosis/prevención & control , TurquíaRESUMEN
Multiple isoforms of UDP-GalNAc:polypeptide N-acetylgalactosaminyl- transferase (ppGaNTase) have been cloned and expressed from a variety of organisms. In general, these isoforms display different patterns of tissue-specific expression, but exhibit overlapping substrate specificities, in vitro . A peptide substrate, derived from the sequence of the V3 loop of the HIV gp120 protein (HIV peptide), has previously been shown to be glycosylated in vitro exclusively by the ppGaNTase-T3 (Bennett et al. , 1996). To determine if this isoform-specificity is maintained in vivo , we have examined the glycosylation of this substrate when it is expressed as a reporter peptide (rHIV) in a cell background (COS7 cells) which lacks detectable levels of the ppGaNTase-T3. Glycosylation of rHIV was greatly increased by coexpression of a recombinant ppGaNTase-T3. Overexpression of ppGaNTase-T1 yielded only partial glycosylation of the reporter. We have also determined that the introduction of a proline residue at the +3 position flanking the potential glycosylation site eliminated ppGaNTase-T3 selectivity toward rHIV observed both in vivo and in vitro .
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Isoenzimas/metabolismo , N-Acetilgalactosaminiltransferasas/metabolismo , Secuencia de Aminoácidos , Animales , Secuencia de Bases , Sitios de Unión/genética , Células COS , Glicosilación , Proteína gp120 de Envoltorio del VIH/química , Proteína gp120 de Envoltorio del VIH/genética , Proteína gp120 de Envoltorio del VIH/metabolismo , Isoenzimas/genética , Datos de Secuencia Molecular , Mutación , N-Acetilgalactosaminiltransferasas/genética , Fragmentos de Péptidos/química , Fragmentos de Péptidos/genética , Fragmentos de Péptidos/metabolismo , Plásmidos/genética , Proteínas Recombinantes/química , Proteínas Recombinantes/genética , Proteínas Recombinantes/metabolismo , Especificidad por Sustrato , Polipéptido N-AcetilgalactosaminiltransferasaRESUMEN
The cDNA for a fourth member of the mammalian UDP-GalNAc:polypeptide N-acetylgalactosaminyltransferase family, termed ppGaNTase-T4, has been cloned from a murine spleen cDNA library and expressed transiently in COS7 cells as a secreted functional enzyme. Degenerate primers, based upon regions that are conserved among the known mammalian members of the enzyme family (ppGaNTase-T1, -T2, and -T3) and three Caenorhabditis elegans homologues (ppGaNTase-TA, -TB, and -TC), were used in polymerase chain reactions to identify and clone this new isoform. Substrate preferences for recombinant murine ppGaNTase-T1 and ppGaNTase-T4 isozymes were readily distinguished. ppGaNTase-T1 glycosylated a broader range of synthetic peptide substrates; in contrast, the ppGaNTase-T4 preferentially glycosylated a single substrate among the panel of 11 peptides tested. Using Northern blot analysis, a ppGaNTase-T4 message of 5.5 kilobases was detectable in murine embryonic tissues, as well as the adult sublingual gland, stomach, colon, small intestine, lung, cervix, and uterus with lower levels detected in kidney, liver, heart, brain, spleen, and ovary. Thus, the pattern of expression for ppGaNTase-T4 is more restricted than for the three previously reported isoforms of the enzyme. The variation in expression patterns and substrate specificities of the ppGaNTase enzyme family suggests that differential expression of these isoenzymes may be responsible for the cell-specific repertoire of mucin-type oligosaccharides on cell-surface and secreted O-linked glycoproteins.