RESUMEN
This first-in-human study of AGN1 LOEP demonstrated that this minimally-invasive treatment durably increased aBMD in femurs of osteoporotic postmenopausal women. AGN1 resorption was coupled with new bone formation by 12 weeks and that new bone was maintained for at least 5-7 years resulting in substantially increased FEA-estimated femoral strength. INTRODUCTION: This first-in-human study evaluated feasibility, safety, and in vivo response to treating proximal femurs of postmenopausal osteoporotic women with a minimally-invasive local osteo-enhancement procedure (LOEP) to inject a resorbable triphasic osteoconductive implant material (AGN1). METHODS: This prospective cohort study enrolled 12 postmenopausal osteoporotic (femoral neck T-score ≤ - 2.5) women aged 56 to 89 years. AGN1 LOEP was performed on left femurs; right femurs were untreated controls. Subjects were followed-up for 5-7 years. Outcomes included adverse events, proximal femur areal bone mineral density (aBMD), AGN1 resorption, and replacement with bone by X-ray and CT, and finite element analysis (FEA) estimated hip strength. RESULTS: Baseline treated and control femoral neck aBMD was equivalent. Treated femoral neck aBMD increased by 68 ± 22%, 59 ± 24%, and 58 ± 27% over control at 12 and 24 weeks and 5-7 years, respectively (p < 0.001, all time points). Using conservative assumptions, FEA-estimated femoral strength increased by 41%, 37%, and 22% at 12 and 24 weeks and 5-7 years, respectively (p < 0.01, all time points). Qualitative analysis of X-ray and CT scans demonstrated that AGN1 resorption and replacement with bone was nearly complete by 24 weeks. By 5-7 years, AGN1 appeared to be fully resorbed and replaced with bone integrated with surrounding trabecular and cortical bone. No procedure- or device-related serious adverse events (SAEs) occurred. CONCLUSIONS: Treating femurs of postmenopausal osteoporotic women with AGN1 LOEP results in a rapid, durable increase in aBMD and femoral strength. These results support the use and further clinical study of this approach in osteoporotic patients at high risk of hip fracture.
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Densidad Ósea , Fracturas de Cadera , Absorciometría de Fotón , Anciano , Anciano de 80 o más Años , Femenino , Fémur/diagnóstico por imagen , Fémur/cirugía , Cuello Femoral/cirugía , Humanos , Persona de Mediana Edad , Posmenopausia , Estudios ProspectivosRESUMEN
The natural reservoir for influenza viruses is waterfowl, and from there they succeeded in crossing the barrier to different mammalian species. We analyzed the adaptation of avian influenza viruses to a mammalian host by passaging an H9N2 strain three times in differentiated swine airway epithelial cells. Using precision-cut slices from the porcine lung to passage the parental virus, isolates from each of the three passages (P1 to P3) were characterized by assessing growth curves and ciliostatic effects. The only difference noted was an increased growth kinetics of the P3 virus. Sequence analysis revealed four mutations: one each in the PB2 and NS1 proteins and two in the HA protein. The HA mutations, A190V and T212I, were characterized by generating recombinant viruses containing either one or both amino acid exchanges. Whereas the parental virus recognized α2,3-linked sialic acids preferentially, the HA190 mutant bound to a broad spectrum of glycans with α2,6/8/9-linked sialic acids. The HA212 mutant alone differed only slightly from the parental virus; however, the combination of both mutations (HA190+HA212) increased the binding affinity to those glycans recognized by the HA190 mutant. Remarkably, only the HA double mutant showed a significantly increased pathogenicity in mice. In contrast, none of those mutations affected the ciliary activity of the epithelial cells which is characteristic for virulent swine influenza viruses. Taken together, our results indicate that shifts in the HA receptor affinity are just an early adaptation step of avian H9N2 strains; further mutational changes may be required to become virulent for pigs.IMPORTANCE Swine play an important role in the interspecies transmission of influenza viruses. Avian influenza A viruses (IAV) of the H9N2 subtype have successfully infected hosts from different species but have not established a stable lineage. We have analyzed the adaptation of IAV-H9N2 virus to target cells of a new host by passaging the virus three times in differentiated porcine respiratory epithelial cells. Among the four mutations detected, the two HA mutations were analyzed by generating recombinant viruses. Depending on the infection system used, the mutations differed in their phenotypic expression, e.g., sialic acid binding activity, replication kinetics, plaque size, and pathogenicity in inbred mice. However, none of the mutations affected the ciliary activity which serves as a virulence marker. Thus, early adaptive mutation enhances the replication kinetics, but more mutations are required for IAV of the H9N2 subtype to become virulent.
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Adaptación Biológica , Células Epiteliales/virología , Subtipo H9N2 del Virus de la Influenza A/genética , Subtipo H9N2 del Virus de la Influenza A/patogenicidad , Ácido N-Acetilneuramínico/metabolismo , Mucosa Respiratoria/virología , Acoplamiento Viral , Animales , Análisis Mutacional de ADN , Glicoproteínas Hemaglutininas del Virus de la Influenza/genética , Subtipo H9N2 del Virus de la Influenza A/crecimiento & desarrollo , Ratones , Mutación Missense , ARN Polimerasa Dependiente del ARN/genética , Genética Inversa , Pase Seriado , Porcinos , Proteínas no Estructurales Virales/genética , Proteínas Virales/genética , VirulenciaRESUMEN
BACKGROUND AND AIMS: Increasing evidence has indicated that insulin resistance is associated with inflammation. However, few studies have investigated the association between white blood cell (WBC) count and insulin resistance, as measured by a homeostasis model assessment of insulin resistance (HOMA-IR) in a general pediatric population. This study aimed to examine the association between WBC count and insulin resistance as measured by HOMA-IR in a nationally representative sample of children and adolescents. METHODS AND RESULTS: In total, 2761 participants (1479 boys and 1282 girls) aged 10-18 years were selected from the 2008-2010 Korean National Health and Nutrition Examination Survey. Insulin resistance was defined as a HOMA-IR value greater than the 90th percentile. The odds ratios and 95% confidence intervals for insulin resistance were determined using multiple logistic regression analysis. The mean values of most cardiometabolic variables tended to increase proportionally with WBC count quartiles. The prevalence of insulin resistance significantly increased in accordance with WBC count quartiles in both boys and girls. Compared to individuals in the lowest WBC count quartile, the odds ratio for insulin resistance for individuals in the highest quartile was 2.84 in boys and 3.20 in girls, after adjusting for age, systolic blood pressure, body mass index, and waist circumference. CONCLUSION: A higher WBC count was positively associated with an increased risk of insulin resistance in Korean children and adolescents. This study suggests that WBC count could facilitate the identification of children and adolescents with insulin resistance.
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Inflamación/sangre , Resistencia a la Insulina , Recuento de Leucocitos , Síndrome Metabólico/sangre , Adolescente , Factores de Edad , Biomarcadores/sangre , Glucemia/análisis , Niño , Estudios Transversales , Femenino , Humanos , Inflamación/diagnóstico , Inflamación/epidemiología , Insulina/sangre , Modelos Logísticos , Masculino , Síndrome Metabólico/diagnóstico , Síndrome Metabólico/epidemiología , Análisis Multivariante , Encuestas Nutricionales , Oportunidad Relativa , Valor Predictivo de las Pruebas , Prevalencia , República de Corea/epidemiología , Medición de Riesgo , Factores de RiesgoRESUMEN
The inflammation hypothesis of Alzheimer's pathogenesis has directed much scientific effort towards ameliorating this disease. The development of mouse models of amyloid deposition permitted direct tests of the proposal that amyloid-activated microglia could cause neurodegeneration in vivo. Many approaches to manipulating microglial activation have been applied to these mouse models, and are the subject of this review. In general, these results do not support a direct neuricidal action of microglia in mouse amyloid models under any activation state. Some of the manipulations cause both a reduction in pathology and a reduction in microglial activation. However, at least for agents like ibuprofen, this outcome may result from a direct action on amyloid production, and a reduction in the microglial-provoking amyloid deposits, rather than from reduced microglial activation leading to a decline in amyloid deposition. Instead, a surprising number of the experimental manipulations which increase microglial activation lead to enhanced clearance of the amyloid deposits. Both the literature and new data presented here suggest that either classical or alternative activation of microglia can lead to enhanced amyloid clearance. However, a limited number of studies comparing the same treatments in amyloid-depositing vs. tau-depositing mice find the opposite effects. Treatments that benefit amyloid pathology accelerate tau pathology. This observation argues strongly that potential treatments be tested for impact on both amyloid and tau pathology before consideration of testing in humans.
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Enfermedad de Alzheimer/patología , Microglía/patología , Placa Amiloide/patología , Proteínas tau/metabolismo , Enfermedad de Alzheimer/inmunología , Enfermedad de Alzheimer/metabolismo , Péptidos beta-Amiloides/metabolismo , Animales , Modelos Animales de Enfermedad , Ratones , Microglía/inmunología , Microglía/metabolismo , Placa Amiloide/inmunología , Placa Amiloide/metabolismoRESUMEN
We report the design and characterization of external-cavity DBR lasers built with a III-V-semiconductor reflective-SOA with spot-size converter edge-coupled to SOI waveguides containing Bragg grating mirrors. The un-cooled lasers have wall-plug-efficiencies of up to 9.5% at powers of 6 mW. The lasers are suitable for making power efficient, hybrid WDM transmitters in a CMOS-compatible SOI optical platform.
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Rayos Láser , Lentes , Refractometría/instrumentación , Semiconductores , Transferencia de Energía , Diseño de Equipo , Análisis de Falla de EquipoRESUMEN
1. Hyper-induction of cytokines and chemokines was found in human blood macrophages infected with the avian influenza H5N1 and H9N2/G1 viruses, as compared to those infected with human influenza H1N1 virus. 2. IRF3 played a significant role in the hyperinduction of cytokines including IFN-ß, IFN-λ1,IFN-α subtypes, MCP-1, and TNF-α, and also played a part in subsequent cytokine-induced cell signalling cascades. 3. Compared with H1N1 viruses, avian influenza viruses including H5N1/97 and its precursors triggered a caspase-mediated but delayed apoptotic response in human macrophages. 4. Therapies that can minimise immunopathology-associated dysregulation of innate immunity without impairing effective host defence may be valuable adjuncts to antiviral therapy.
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Apoptosis , Citocinas/genética , Subtipo H5N1 del Virus de la Influenza A , Gripe Humana/metabolismo , Factor 3 Regulador del Interferón/metabolismo , Macrófagos/metabolismo , ARN Mensajero/metabolismo , Caspasa 3/metabolismo , Células Cultivadas , Citocinas/biosíntesis , Regulación de la Expresión Génica , Humanos , Subtipo H1N1 del Virus de la Influenza A , Factor 3 Regulador del Interferón/genética , Interferón beta/biosíntesis , Interferón beta/genética , Interferones , Interleucinas/biosíntesis , Interleucinas/genética , Macrófagos/enzimología , Macrófagos/virología , Poli(ADP-Ribosa) Polimerasas/metabolismo , ARN Interferente Pequeño , Factores de Transcripción/metabolismo , Factor de Necrosis Tumoral alfa/biosíntesis , Factor de Necrosis Tumoral alfa/genética , Regulación hacia Arriba/genéticaRESUMEN
MicroRNAs (miRNAs) are involved in the post-transcriptional regulation of gene expression during development. This study was performed to determine gestational age-dependent changes in miRNA expression in the chorioamniotic membranes and to assess the significance of miRNAs in human pregnancy and parturition. The expression profile of 455 miRNAs was compared between patients at term without labour (TNL: n = 10), in labour (TL: n = 10), and preterm labour (PTL: n = 10) using microarrays. A total of 39 miRNAs were differentially expressed between term and preterm cases, of which 31 (79.5%) were down-regulated at term. Expression of ten miRNAs, including miR-338, differentially expressed between PTL and TL groups was decreased at term. Computational analyses using miRBase Targets have identified PLA2G4B, a phospholipase implicated in parturition, as a putative target of miR-338. Inhibition of endogenous miR-338 with anti-miR-338 increased the mRNA and protein expression of PLA2G4B in decidual cells. Luciferase assay with reporter constructs confirmed that the suppression of PLA2G4B occurs through binding of miR-338 to the 3UTR of PLA2G4B. Interestingly, the expression of Dicer, a key miRNA-processing enzyme, was markedly decreased at term, particularly with labour in the chorioamniotic membranes. Collectively, the novel findings reported herein strongly suggest that post-transcriptional regulation of genes by miRNAs, coupled with the changes of miRNA processing machinery in the chorioamniotic membranes, plays a role in pregnancy and parturition. Furthermore, the expression level of Dicer in the chorioamniotic membranes dichotomizes pathological preterm labour and physiological spontaneous labour at term.
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Amnios/metabolismo , Corion/metabolismo , MicroARNs/metabolismo , Embarazo/genética , Adolescente , Adulto , Secuencia de Bases , Peso al Nacer , Decidua/metabolismo , Regulación hacia Abajo , Femenino , Perfilación de la Expresión Génica/métodos , Edad Gestacional , Fosfolipasas A2 Grupo IV/biosíntesis , Fosfolipasas A2 Grupo IV/genética , Humanos , Cariotipificación , MicroARNs/fisiología , Datos de Secuencia Molecular , Trabajo de Parto Prematuro/genética , Trabajo de Parto Prematuro/metabolismo , Análisis de Secuencia por Matrices de Oligonucleótidos/métodos , Parto/genética , Parto/metabolismo , Embarazo/metabolismo , Proteínas Gestacionales/genética , Proteínas Gestacionales/metabolismo , Ribonucleasa III/metabolismo , Adulto JovenRESUMEN
OBJECTIVE: Handgrip strength is considered a biomarker of nutritional status and strength capacity, which are both linked to heart complications. However, it is not well understood how weakness, as measured by handgrip strength, factors into common heart conditions seen in aging adults such as chronic heart failure (CHF). The purpose of this study was to determine the association between weakness and incident CHF for aging Americans. DESIGN: Longitudinal-Panel. SETTING: Physical measures were completed during enhanced face-to-face interviews. The core interview was typically conducted over the telephone. PARTICIPANTS: Data from 17,431 adults aged at least 50 years who identified as Black or White, completed interviews without a proxy, and participated in at least one wave of the 2006-2014 waves of the Health and Retirement Study were included. MEASUREMENTS: Handgrip strength was measured with a hand-held dynamometer. Healthcare provider diagnosed CHF was self-reported at each wave. Sex- and race-specific maximal handgrip strength cut-points were used for determining weakness (Black men: <40-kilograms, Black women: <31-kilograms, White men: <35-kilograms, White women: <22-kilograms). A covariate-adjusted Cox model analyzed the association between weakness and incident CHF. RESULTS: Of those included, 5,397 (31.0%) were weak and 327 (1.9%) developed CHF during the mean follow-up of 4.7±2.7 years. Those who were weak had a 35% higher risk (hazard ratio: 1.35; 95% confidence interval: 1.05, 1.74) of developing CHF, compared to those who were not-weak. CONCLUSION: Measures of handgrip strength should be utilized by healthcare providers for assessing age-related weakness, nutritional status, and CHF risk. Likewise, interventions aiming to prevent or treat CHF in aging adults should incorporate measures of handgrip strength for helping to determine efficacy of intervention programs.
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Envejecimiento/fisiología , Fuerza de la Mano/fisiología , Insuficiencia Cardíaca/fisiopatología , Debilidad Muscular/fisiopatología , Estado Nutricional/fisiología , Negro o Afroamericano , Anciano , Femenino , Humanos , Masculino , Persona de Mediana Edad , Modelos de Riesgos Proporcionales , Jubilación , Autoinforme , Encuestas y CuestionariosRESUMEN
Milankovitch orbital forcing theory has been used to assign time scales to many paleoclimate records. However, the validity of this theory remains uncertain, and independent sea-level chronologies used to test its applicability have been restricted largely to the past approximately 135,000 years. Here, we report U-series ages for coral reefs formed on Henderson Island during sea-level high-stands occurring at approximately 630,000 and approximately 330,000 years ago. These data are consistent with the hypothesis that interglacial climates are forced by Northern Hemisphere summer solar insolation centered at 65 degrees N latitude, as predicted by Milankovitch theory.
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Clima , Cnidarios , Animales , Cnidarios/química , Cnidarios/crecimiento & desarrollo , Espectrometría de Masas , Islas del Pacífico , Radioisótopos/análisis , Agua de Mar , Torio/análisis , Tiempo , Uranio/análisisRESUMEN
We have determined the abundances of 16O, 17O, and 18O in 31 lunar samples from Apollo missions 11, 12, 15, 16, and 17 using a high-precision laser fluorination technique. All oxygen isotope compositions plot within +/-0.016 per mil (2 standard deviations) on a single mass-dependent fractionation line that is identical to the terrestrial fractionation line within uncertainties. This observation is consistent with the Giant Impact model, provided that the proto-Earth and the smaller impactor planet (named Theia) formed from an identical mix of components. The similarity between the proto-Earth and Theia is consistent with formation at about the same heliocentric distance. The three oxygen isotopes (delta17O) provide no evidence that isotopic heterogeneity on the Moon was created by lunar impacts.
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Evolución Planetaria , Luna , Isótopos de Oxígeno , Oxígeno , Simulación por Computador , Medio Ambiente Extraterrestre , MeteoroidesRESUMEN
The ectodomains of numerous proteins are released from cells by proteolysis to yield soluble intercellular regulators. The responsible protease, tumor necrosis factor-alpha converting enzyme (TACE), has been identified only in the case when tumor necrosis factor-alpha (TNFalpha) is released. Analyses of cells lacking this metalloproteinase-disintegrin revealed an expanded role for TACE in the processing of other cell surface proteins, including a TNF receptor, the L-selectin adhesion molecule, and transforming growth factor-alpha (TGFalpha). The phenotype of mice lacking TACE suggests an essential role for soluble TGFalpha in normal development and emphasizes the importance of protein ectodomain shedding in vivo.
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Membrana Celular/metabolismo , Desarrollo Embrionario y Fetal , Proteínas de la Membrana/metabolismo , Metaloendopeptidasas/metabolismo , Factor de Necrosis Tumoral alfa/metabolismo , Proteínas ADAM , Proteína ADAM17 , Secuencia de Aminoácidos , Animales , Dominio Catalítico , Células Cultivadas , Cruzamientos Genéticos , Selectina L/metabolismo , Ligandos , Metaloendopeptidasas/química , Metaloendopeptidasas/genética , Ratones , Ratones Endogámicos C57BL , Datos de Secuencia Molecular , Mutación , Fenotipo , Procesamiento Proteico-Postraduccional , Receptores del Factor de Necrosis Tumoral/metabolismo , Factor de Crecimiento Transformador alfa/metabolismoRESUMEN
BACKGROUND AND PURPOSE: Recently, orthostatic hypotension was observed in patients with benign prostatic hyperplasia who are taking vardenafil (a PDE 5 inhibitor) and terazosin (a long acting alpha blocker). Therefore, this study was performed with DA-8159 (a long acting PDE 5 inhibitor) and terazosin in rats to find whether or not pharmacokinetic and pharmacodynamic interactions between the two drugs were observed. EXPERIMENTAL APPROACH: Pharmacokinetic and pharmacodynamic (changes in blood pressure) interactions between DA-8159 and terazosin were evaluated after simultaneous i.v. and p.o. administration of DA-8159 (30 mg kg(-1)) and terazosin (5 mg kg(-1)) to male Sprague-Dawley rats. KEY RESULTS: After simultaneous i.v. and p.o. administration of terazosin and DA-8159, the total area under the plasma concentration-time curve from time zero to time infinity (AUC) of terazosin became significantly greater (57.4 and 75.4% increase for i.v. and p.o. administration, respectively) than those of without DA-8159. The blood pressure dropping effect was considerable after simultaneous p.o. administration of DA-8159 and terazosin compared with each drug alone. CONCLUSIONS AND IMPLICATIONS: The significantly greater AUC of terazosin after both simultaneous i.v. and p.o. administration of both drugs could be due to the hepatic (both i.v. and p.o.) and intestinal (p.o.) inhibition of the metabolism of terazosin via CYP3A1 and/or 3A2 by DA-8159, since both DA-8159 and terazosin are metabolized via CYP3A1 and/or 3A2 in rats. The blood pressure lowering effect after simultaneous p.o. administration of both drugs could be due to significant increase in plasma concentrations of terazosin.
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Hidrocarburo de Aril Hidroxilasas/fisiología , Proteínas de la Membrana/fisiología , Prazosina/análogos & derivados , Pirimidinas/farmacología , Animales , Citocromo P-450 CYP3A , Dexametasona/farmacología , Interacciones Farmacológicas , Masculino , Microsomas Hepáticos/metabolismo , Prazosina/administración & dosificación , Prazosina/farmacocinética , Pirimidinas/farmacocinética , Ratas , Ratas Sprague-Dawley , Sulfonamidas , Troleandomicina/farmacologíaRESUMEN
We examined the transcription of a variety of adenovirus type 2 genes in a cell-free system containing purified ribonucleic acid polymerase II and a crude extract from cultured human cells. The early EIA, EIB, EIII, and EIV genes and the intermediate polypeptide IX gene, all of which contain a recognizable TATAA sequence upstream from the cap site, were actively transcribed in vitro, albeit with apparently different efficiencies, whereas the early EII (map position 74.9) and IVa2 genes, both of which lack a TATAA sequence, were not actively transcribed. A reverse transcriptase-primer extension analysis showed that the 5' ends of the in vitro transcripts were identical to those of the corresponding in vivo ribonucleic acids and that, in those instances where initiation was heterogeneous in vivo, a similar kind of heterogeneity was observed in the cell-free system. Transcription of the polypeptide IX gene indicated that this transcript was not terminated at, or processed to, the polyadenylic acid addition site in vitro. We also failed to observe, using the in vitro system, any indication of transcriptional regulation based on the use of adenovirus type 2-infected cell extracts.
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Adenovirus Humanos/genética , Regiones Promotoras Genéticas , Transcripción Genética , Sistema Libre de Células , Células Cultivadas , Mapeo Cromosómico , Genes Virales , Humanos , ARN Polimerasa II/metabolismoRESUMEN
Expression of the gene encoding transforming growth factor-alpha (TGF alpha) was examined in developing rat embryos by using a cloned TGF alpha cDNA as a hybridization probe. Northern blot analysis of RNA isolated from whole fetuses revealed that TGF alpha mRNA was present at relatively high levels in 8- through 10-day-old embryos and then declined to the low or undetectable level, which is characteristic of adult tissues before birth. The level of TGF alpha mRNA present during early gestation was similar to that present in retrovirus-transformed cells in culture, suggesting that TGF alpha expression is not highly localized in the embryo. These observations are consistent with the hypothesis that TGF alpha plays a role in development, possibly as a fetal growth factor.
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Péptidos/genética , ARN Mensajero/genética , Animales , Embrión de Mamíferos/metabolismo , Regulación de la Expresión Génica , Edad Gestacional , Biosíntesis de Péptidos , Ratas , Factores de Crecimiento TransformadoresRESUMEN
Two independent cDNA clones corresponding to a 2.7-kilobase (kb) epidermal growth factor receptor (EGF-R) mRNA were isolated from a rat liver cDNA library. Sequence analysis revealed 100% homology in the external domain when compared with the full-length rat EGF-R nucleotide sequence and 80 to 90% similarity relative to the human EGF-R. However, the 3'-terminal sequence of these clones did not match EGF-R or any other known sequence(s) and was distinct from the 3' end of the 2.8-kb mRNA, which encodes a truncated EGF-R in A431 cells. The deduced amino acid sequence revealed an open reading frame which is homologous to the external domain of the EGF-R but which terminates prior to the transmembrane region. Southern blot analysis of rat genomic DNA indicated that the 3'-terminal sequence of this transcript is derived from the EGF-R gene. Analysis of a genomic clone containing the 3' end of the 2.7-kb transcript revealed that this sequence is present as a discrete exon in the mid-region of the receptor gene in proximity to the exon encoding the transmembrane domain. Introduction of an expression vector containing the truncated EGF-R cDNA into Chinese hamster ovary (CHO) cells led to the expression of a 95-kilodalton protein which was detected in conditioned media, by using antisera directed against the EGF-R. A similarly sized protein was also detected in the media of WB cells, a continuous, nontransformed line of rat hepatic epithelial cells. Northern (RNA blot) analysis established that the truncated receptor is encoded by a 2.7-kb transcript found in normal rat liver. Furthermore, Northern analysis of rat poly(A)+ RNA showed that the 2.7-kb EGF-R transcript is expressed at differing levels in various fetal and adult tissues. These data indicate that alternative splicing of the EGF-R primary transcript yields a 2.7-kb mRNA which codes for a truncated form of the receptor. This receptor is secreted by rat hepatic epithelial cells in culture, which suggests that it may be secreted by normal rat cells or tissues and perhaps serve an as yet unknown physiological function.
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Receptores ErbB/genética , Empalme del ARN , Transcripción Genética , Secuencia de Aminoácidos , Animales , Secuencia de Bases , Clonación Molecular , ADN/genética , ADN/aislamiento & purificación , Desoxirribonucleasa EcoRI , Exones , Biblioteca de Genes , Humanos , Intrones , Hígado/metabolismo , Datos de Secuencia Molecular , ARN Mensajero/genética , Ratas , Homología de Secuencia de Ácido NucleicoRESUMEN
We have determined the complete nucleotide sequence of rat transforming growth factor alpha (TGF alpha) mRNA and characterized the six exons that encode this transcript. These six exons span approximately 85 kilobases of genomic DNA, with exons 1 to 3 separated by particularly large introns. What had previously been thought to represent a species-specific difference in the size of the TGF alpha precursor (proTGF alpha) is now shown to be due to microheterogeneity in the splicing of exons 2 and 3. This results from a tandem duplication of the acceptor CAG and gives rise to two alternate forms (159 and 160 amino acids) of the integral membrane precursor. Exon 6, which encodes the 3' untranslated region of TGF alpha mRNA, also encodes, on the opposite strand, a small (approximately 200-nucleotide) transcript whose sequence predicts an open reading frame of 51 amino acids. Expression of this latter transcript does not appear to be coregulated with that of TGF alpha mRNA. Primer extension and S1 nuclease analyses of authentic TGF alpha transcripts revealed two major and multiple minor 5' ends which span more than 200 base pairs of DNA in a G + C-rich region that lacks canonical CCAAT or TATA sequences. The 5' ends of six independently derived cDNAs localized to five different sites in this same region. Restriction fragments that overlap these transcription start sites and extend approximately 300 base pairs in the 5' direction faithfully promote transcription in vitro with HeLa cell nuclear extracts. In addition, they direct the expression of the bacterial chloramphenicol acetyltransferase gene in transient-transfection assays.
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Factores de Crecimiento Transformadores/genética , Secuencia de Aminoácidos , Animales , Secuencia de Bases , Clonación Molecular , ADN/genética , Expresión Génica , Genes , Intrones , Datos de Secuencia Molecular , Regiones Promotoras Genéticas , ARN Mensajero/genética , Ratas/genética , Secuencias Reguladoras de Ácidos Nucleicos , Mapeo RestrictivoRESUMEN
Previous studies have shown that transforming growth factor alpha is expressed during rodent development. To establish the site(s) of transforming growth factor alpha mRNA expression during rat embryogensis, we performed in situ hybridization and Northern blot analyses on samples of embryonic and maternal tissues at various gestational ages. Our results indicate that the high levels of transforming growth factor alpha mRNA that are observed during early development are the result of expression in the maternal decidua and not in the embryo. Decidual expression appears to be induced after implantation, peaks at day 8, and then slowly declines through day 15 at which time the decidua is being resorbed. Expression of transforming growth factor alpha mRNA is highest in that region of the decidua adjacent to the embryo and is low or nondetectable in the uterus, placenta, and other maternal tissues. The developmentally regulated expression of transforming growth factor alpha mRNA in the decidua, together with the presence of epidermal growth factor receptors in this tissue, suggests that transforming growth factor alpha stimulates proliferation locally through an autocrine mechanism. Since epidermal growth factor receptors are present in the embryo and placenta, transforming growth factor alpha produced in the decidua may also act on these tissues through paracrine or endocrine mechanisms.
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Decidua/metabolismo , Biosíntesis de Péptidos , Animales , Embrión de Mamíferos/metabolismo , Femenino , Regulación de la Expresión Génica , Edad Gestacional , Péptidos/genética , Embarazo , ARN Mensajero/genética , ARN Mensajero/metabolismo , Ratas , Ratas Endogámicas , Distribución Tisular , Factores de Crecimiento TransformadoresRESUMEN
Analysis of a cDNA clone derived from retrovirus-transformed rat fibroblasts has recently suggested that the mature 50-amino-acid form of transforming growth factor alpha (TGF alpha) is derived from a 159-amino-acid transmembrane precursor by proteolytic cleavage. To understand the processing of the TGF alpha precursor molecule in more detail, we have expressed this protein in baby hamster kidney (BHK) fibroblasts under control of the metal-ion-inducible metallothionein promoter and characterized the expressed precursor with site-specific antipeptide antibodies. One of the BHK transfectants, termed 5:2, expressed the TGF alpha mRNA in a cadmium- and zinc-inducible manner. The TGF alpha precursor protein was detected by immunoprecipitation analysis of radiolabeled cell cultures. In the induced 5:2 cells, a polypeptide of Mr 13,000 to 17,000 was readily identified by peptide antisera made to three different regions of the TGF alpha precursor protein. No such protein species were observed in BHK cells treated with cadmium and zinc or in uninduced 5:2 cells. However, two cell lines known to produce TGF alpha naturally, Leydig testicular tumor cells and Snyder-Theilan feline sarcoma virus-transformed Fisher rat embryo fibroblasts, possessed detectable levels of immunologically related Mr 13,000 to 17,000 proteins. Cell fractionation studies indicate that the Mr 13,000 to 17,000 species expressed in induced 5:2 cells is membrane associated, consistent with predictions based on the cDNA sequence of the TGF alpha precursor. Media conditioned by induced 5:2 cells contained epidermal growth factor receptor-competing activity, which, upon size fractionation, was similar in size to the mature processed form of TGF alpha. These data show that these nontransformed BHK cells possess the ability to process the TGF alpha precursor molecule into its native form.