RESUMO
NAA20 is the catalytic subunit of the NatB complex, which is responsible for N-terminal acetylation of approximately 20% of the human proteome. Recently, pathogenic biallelic variants in NAA20 were associated with a novel neurodevelopmental disorder in five individuals with limited clinical information. We report two sisters harboring compound heterozygous variant (c.100C>T (p.Gln34Ter) and c.11T>C p.(Leu4Pro)) in the NAA20 gene, identified by exome sequencing. In vitro studies showed that the missense variant p.Leu4Pro resulted in a reduction of NAA20 catalytic activity due to weak coupling with the NatB auxiliary subunit. In addition, unpublished data of the previous families were reported, outlining the core phenotype of the NAA20-related disorder mostly characterized by cognitive impairment, microcephaly, ataxia, brain malformations, dysmorphism and variable occurrence of cardiac defect and epilepsy. Remarkably, our two patients featured epilepsy onset in adolescence suggesting this may be a part of syndrome evolution. Functional studies are needed to better understand the complexity of NAA20 variants pathogenesis as well as of other genes linked to N-terminal acetylation.
Assuntos
Microcefalia , Malformações do Sistema Nervoso , Adolescente , Humanos , Domínio Catalítico , Microcefalia/genética , Síndrome , Fenótipo , Acetiltransferase N-Terminal B/genética , Acetiltransferase N-Terminal B/metabolismoRESUMO
Here, we report the detection and complete genome sequence of a novel potexvirus, tentatively named "Adenium obesum virus X" (AobVX), isolated from Adenium obesum, that was sent for virus screening at Australian Government post-entry quarantine (PEQ) facilities after being imported into Australia from China. The AobVX genome is 6781 nucleotides in length excluding the poly(A) tail and is predicted to encode conserved potexvirus proteins and sequence motifs across five open reading frames. The RNA-dependent RNA polymerase of this virus shares the highest amino acid sequence similarity with that of nerine potexvirus 1 (58.7% identity) and nerine virus X (58.58% identity). This is the first report of a positive-sense single-stranded RNA virus in A. obesum related to members of the genus Potexvirus in the family Alphaflexiviridae.
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Apocynaceae , Potexvirus , Apocynaceae/virologia , Potexvirus/classificação , Potexvirus/genética , Potexvirus/isolamento & purificação , Filogenia , Genoma Viral , RNA Polimerase Dependente de RNA/genéticaRESUMO
Synonymous variants have been shown to alter the correct splicing of pre-mRNAs and generate disease-causing transcripts. These variants are not an uncommon etiology of genetic disease; however, they are frequently overlooked during genetic testing in the absence of functional and clinical data. Here, we describe the occurrence of a synonymous variant [NM_005422.4 (TECTA):c.327C>T, p.(Gly109=)] in seven individuals with hearing loss from six unrelated families. The variant is not located near exonic/intronic boundaries but is predicted to impact splicing by activating a cryptic splicing donor site in exon 4 of TECTA. In vitro minigene assays show that the variant disrupts the reading frame of the canonical transcript, which is predicted to cause a premature termination codon 48 amino acids downstream of the variant, leading to nonsense-mediated decay. The variant is present in population databases, predominantly in Latinos of African ancestry, but is rare in other ethnic groups. Our findings suggest that this synonymous variant is likely pathogenic for TECTA-associated autosomal recessive hearing loss and seems to have arisen as a founder variant in this specific Latino subpopulation. This study demonstrates that synonymous variants need careful splicing assessment and support from additional testing methodologies to determine their clinical impact.
Assuntos
Surdez , Perda Auditiva , Humanos , Sítios de Splice de RNA , Splicing de RNA/genética , Perda Auditiva/genética , Surdez/genética , Éxons/genética , Proteínas da Matriz Extracelular/genética , Proteínas Ligadas por GPI/genéticaRESUMO
PURPOSE: N-terminal acetyltransferases modify proteins by adding an acetyl moiety to the first amino acid and are vital for protein and cell function. The NatB complex acetylates 20% of the human proteome and is composed of the catalytic subunit NAA20 and the auxiliary subunit NAA25. In five individuals with overlapping phenotypes, we identified recessive homozygous missense variants in NAA20. METHODS: Two different NAA20 variants were identified in affected individuals in two consanguineous families by exome and genome sequencing. Biochemical studies were employed to assess the impact of the NAA20 variants on NatB complex formation and catalytic activity. RESULTS: Two homozygous variants, NAA20 p.Met54Val and p.Ala80Val (GenBank: NM_016100.4, c.160A>G and c.239C>T), segregated with affected individuals in two unrelated families presenting with developmental delay, intellectual disability, and microcephaly. Both NAA20-M54V and NAA20-A80V were impaired in their capacity to form a NatB complex with NAA25, and in vitro acetylation assays revealed reduced catalytic activities toward different NatB substrates. Thus, both NAA20 variants are impaired in their ability to perform cellular NatB-mediated N-terminal acetylation. CONCLUSION: We present here a report of pathogenic NAA20 variants causing human disease and data supporting an essential role for NatB-mediated N-terminal acetylation in human development and physiology.
Assuntos
Deficiência Intelectual , Microcefalia , Acetiltransferases , Humanos , Deficiência Intelectual/genética , Microcefalia/genética , Acetiltransferase N-Terminal BRESUMO
BACKGROUND: Thyroid cancer is the most common endocrine malignancy, and many patients with metastatic differentiated thyroid cancer (DTC), poorly differentiated thyroid cancer (PDTC), and anaplastic thyroid cancer (ATC) fail to respond to conventional therapies, resulting in morbidity and mortality. Additional therapeutic targets and treatment options are needed for these patients. We recently reported that peroxisome proliferator-activated receptor gamma (PPARγ) is highly expressed in ATC and confers an aggressive phenotype when overexpressed in DTC cells. METHODS: Microarray analysis was used to identify downstream targets of PPARγ in ATC cells. Western blot analysis and immunohistochemistry (IHC) were used to assess thioredoxin interacting protein (TXNIP) expression in thyroid cancer cell lines and primary tumor specimens. Retroviral transduction was used to generate ATC cell lines that overexpress TXNIP, and assays that assess glucose uptake, viable cell proliferation, and invasion were used to characterize the in vitro properties of these cells. An orthotopic thyroid cancer mouse model was used to assess the effect of TXNIP overexpression in ATC cell lines in vivo. RESULTS: Using microarray analysis, we show that TXNIP is highly upregulated when PPARγ is depleted from ATC cells. Using Western blot analysis and IHC, we show that DTC and ATC cells exhibit differential TXNIP expression patterns. DTC cell lines and patient tumors have high TXNIP expression in contrast to low or absent expression in ATC cell lines and tumors. Overexpression of TXNIP decreases the growth of HTh74 cells compared to vector controls and inhibits glucose uptake in the ATC cell lines HTh74 and T238. Importantly, TXNIP overexpression in T238 cells results in attenuated tumor growth and decreased metastasis in an orthotopic thyroid cancer mouse model. CONCLUSIONS: Our findings indicate that TXNIP functions as a tumor suppressor in thyroid cells, and its downregulation is likely important in the transition from differentiated to advanced thyroid cancer. These studies underscore the potential of TXNIP as a novel therapeutic target and prognostic indicator in advanced thyroid cancer.
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Proteínas de Transporte/genética , Proteínas de Transporte/metabolismo , Genes Supressores de Tumor/fisiologia , Neoplasias da Glândula Tireoide/genética , Neoplasias da Glândula Tireoide/metabolismo , Animais , Western Blotting , Linhagem Celular Tumoral , Xenoenxertos , Humanos , Imuno-Histoquímica , Camundongos , Análise de Sequência com Séries de Oligonucleotídeos , Reação em Cadeia da Polimerase Via Transcriptase Reversa , Transdução GenéticaRESUMO
INTRODUCTION: Does telehealth decrease health disparities by improving connections to care or simply result in new barriers for vulnerable populations who often lack access to technology? This study aims to better understand the role of telehealth and social determinants of health in improving care connections and outcomes for Community Health Center patients with diabetes. METHODS: This retrospective analysis of Electronic Health Record (EHR) data examined the relationship between telehealth utilization and glycemic control and consistency of connection to the health care team ("connectivity"). EHR data were collected from 20 Community Health Centers from July 1, 2019 through December 31, 2021. Descriptive statistics were calculated, and multivariable linear regression was used to assess the associations between telehealth use and engagement in care and glycemic control. RESULTS: The adjusted analysis found positive, statistically significant associations between telehealth use and each of the 2 primary outcomes. Telehealth use was associated with 0.89 additional months of hemoglobin A1c (HbA1c) control (95% confidence interval [CI], 0.73 to 1.04) and 4.49 additional months of connection to care (95% CI, 4.27 to 4.70). DISCUSSION: The demonstrated increased engagement in primary care for telehealth users is significant and encouraging as Community Health Center populations are at greater risk of lapses in care and loss to follow up. CONCLUSIONS: Telehealth can be a highly effective, patient-centered form of care for people with diabetes. Telehealth can play a critical role in keeping vulnerable patients with diabetes connected to their care team and involved in care and may be an important tool for reducing health disparities.
Assuntos
Centros Comunitários de Saúde , Diabetes Mellitus , Hemoglobinas Glicadas , Telemedicina , Humanos , Telemedicina/estatística & dados numéricos , Centros Comunitários de Saúde/estatística & dados numéricos , Centros Comunitários de Saúde/organização & administração , Estudos Retrospectivos , Masculino , Feminino , Pessoa de Meia-Idade , Diabetes Mellitus/terapia , Hemoglobinas Glicadas/análise , Idoso , Registros Eletrônicos de Saúde/estatística & dados numéricos , Adulto , Determinantes Sociais da Saúde , Controle Glicêmico/estatística & dados numéricos , Acessibilidade aos Serviços de Saúde/estatística & dados numéricosRESUMO
OBJECTIVE: COASY, the gene encoding the bifunctional enzyme CoA synthase, which catalyzes the last two reactions of cellular de novo coenzyme A (CoA) biosynthesis, has been linked to two exceedingly rare autosomal recessive disorders, such as COASY protein-associated neurodegeneration (CoPAN), a form of neurodegeneration with brain iron accumulation (NBIA), and pontocerebellar hypoplasia type 12 (PCH12). We aimed to expand the phenotypic spectrum and gain insights into the pathogenesis of COASY-related disorders. METHODS: Patients were identified through targeted or exome sequencing. To unravel the molecular mechanisms of disease, RNA sequencing, bioenergetic analysis, and quantification of critical proteins were performed on fibroblasts. RESULTS: We identified five new individuals harboring novel COASY variants. While one case exhibited classical CoPAN features, the others displayed atypical symptoms such as deafness, language and autism spectrum disorders, brain atrophy, and microcephaly. All patients experienced epilepsy, highlighting its potential frequency in COASY-related disorders. Fibroblast transcriptomic profiling unveiled dysregulated expression in genes associated with mitochondrial respiration, responses to oxidative stress, transmembrane transport, various cellular signaling pathways, and protein translation, modification, and trafficking. Bioenergetic analysis revealed impaired mitochondrial oxygen consumption in COASY fibroblasts. Despite comparable total CoA levels to control cells, the amounts of mitochondrial 4'-phosphopantetheinylated proteins were significantly reduced in COASY patients. INTERPRETATION: These results not only extend the clinical phenotype associated with COASY variants but also suggest a continuum between CoPAN and PCH12. The intricate interplay of altered cellular processes and signaling pathways provides valuable insights for further research into the pathogenesis of COASY-associated diseases.
Assuntos
Fenótipo , Transcriptoma , Humanos , Masculino , Feminino , Criança , Pré-Escolar , Epilepsia/genética , Fibroblastos/metabolismo , Adolescente , Transtorno do Espectro Autista/genética , Adulto , TransferasesRESUMO
A critical step in preserving protein homeostasis is the recognition, binding, unfolding, and translocation of protein substrates by six AAA-ATPase proteasome subunits (ATPase-associated with various cellular activities) termed PSMC1-6, which are required for degradation of proteins by 26S proteasomes. Here, we identified 15 de novo missense variants in the PSMC3 gene encoding the AAA-ATPase proteasome subunit PSMC3/Rpt5 in 23 unrelated heterozygous patients with an autosomal dominant form of neurodevelopmental delay and intellectual disability. Expression of PSMC3 variants in mouse neuronal cultures led to altered dendrite development, and deletion of the PSMC3 fly ortholog Rpt5 impaired reversal learning capabilities in fruit flies. Structural modeling as well as proteomic and transcriptomic analyses of T cells derived from patients with PSMC3 variants implicated the PSMC3 variants in proteasome dysfunction through disruption of substrate translocation, induction of proteotoxic stress, and alterations in proteins controlling developmental and innate immune programs. The proteostatic perturbations in T cells from patients with PSMC3 variants correlated with a dysregulation in type I interferon (IFN) signaling in these T cells, which could be blocked by inhibition of the intracellular stress sensor protein kinase R (PKR). These results suggest that proteotoxic stress activated PKR in patient-derived T cells, resulting in a type I IFN response. The potential relationship among proteosome dysfunction, type I IFN production, and neurodevelopment suggests new directions in our understanding of pathogenesis in some neurodevelopmental disorders.
Assuntos
Interferon Tipo I , Complexo de Endopeptidases do Proteassoma , Animais , Humanos , Camundongos , Adenosina Trifosfatases/genética , Drosophila melanogaster , Expressão Gênica , Complexo de Endopeptidases do Proteassoma/metabolismo , ProteômicaRESUMO
Marion, a university lecturer aged 48 years, presented to her general practitioner complaining of persistent hoarseness for 4-5 weeks. Over the preceding 5 months she had suffered two prolonged episodes of bacterial sinusitis and an infective exacerbation of her asthma, each requiring several weeks of various antibiotics and oral prednisone, and each associated with transient hoarseness.
Assuntos
Candidíase/diagnóstico , Rouquidão/etiologia , Laringite/microbiologia , Corticosteroides/efeitos adversos , Anti-Inflamatórios/efeitos adversos , Asma/complicações , Asma/tratamento farmacológico , Candidíase/complicações , Feminino , Humanos , Laringite/diagnóstico , Pessoa de Meia-Idade , Fatores de RiscoRESUMO
Introduction. Allergen-specific IgE (sIgE) testing provides an objective assessment of sensitization to an allergen. Goal. To identify the time when serum measurements of sIgE would be most sensitive. Methods. This was a prospective study conducted between September 1, 2015, and February 25, 2019. Subjects ≥5 and ≤18 years of age, seen in the ED or admitted with an asthma exacerbation, were tested for total IgE and 8 perennial sIgE levels. Subjects with elevated sIgE were tested again after symptom resolution. Results. A total of 104 subjects were enrolled; 50 subjects were eligible for inclusion in the analysis. There were statistically significant differences between the visits for all sIgE, except Alternaria alternatum. Conclusions. In pediatric patients, serum sIgE levels measured during an asthma exacerbation were elevated compared with when their asthma was in better control. sIgE testing during an asthma exacerbation may help identify asthma triggers, mitigate exposure, and hence improve asthma control.
Assuntos
Asma/diagnóstico , Imunoglobulina E/sangue , Adolescente , Alérgenos/sangue , Biomarcadores/sangue , Criança , Pré-Escolar , Progressão da Doença , Feminino , Humanos , Masculino , Estudos Prospectivos , Rinite Alérgica Perene/diagnóstico , Fatores de RiscoRESUMO
In contrast to Eurasia and North America, powdery mildews (Ascomycota, Erysiphales) are understudied in Australia. There are over 900 species known globally, with fewer than currently 60 recorded from Australia. Some of the Australian records are doubtful as the identifications were presumptive, being based on host plant-pathogen lists from overseas. The goal of this study was to provide the first comprehensive catalog of all powdery mildew species present in Australia. The project resulted in (i) an up-to-date list of all the taxa that have been identified in Australia based on published DNA barcode sequences prior to this study; (ii) the precise identification of 117 specimens freshly collected from across the country; and (iii) the precise identification of 30 herbarium specimens collected between 1975 and 2013. This study confirmed 42 species representing 10 genera, including two genera and 13 species recorded for the first time in Australia. In Eurasia and North America, the number of powdery mildew species is much higher. Phylogenetic analyses of powdery mildews collected from Acalypha spp. resulted in the transfer of Erysiphe acalyphae to Salmonomyces, a resurrected genus. Salmonomyces acalyphae comb. nov. represents a newly discovered lineage of the Erysiphales. Another taxonomic change is the transfer of Oidium ixodiae to Golovinomyces. Powdery mildew infections have been confirmed on 13 native Australian plant species in the genera Acacia, Acalypha, Cephalotus, Convolvulus, Eucalyptus, Hardenbergia, Ixodia, Jagera, Senecio, and Trema. Most of the causal agents were polyphagous species that infect many other host plants both overseas and in Australia. All powdery mildews infecting native plants in Australia were phylogenetically closely related to species known overseas. The data indicate that Australia is a continent without native powdery mildews, and most, if not all, species have been introduced since the European colonization of the continent.
RESUMO
Vehicles cause environmental damage on sandy beaches, including physical displacement and compaction of the sediment. Such physical habitat disturbance provides a relatively simple indicator of ORV-related impacts that is potentially useful in monitoring the efficacy of beach traffic management interventions; such interventions also require data on the relationship between traffic volumes and the resulting levels of impact. Here we determined how the extent of beach disturbance is linked to traffic volumes and tested the utility of image-based data acquisition to monitor beach surfaces. Experimental traffic application resulted in disturbance effects ranging from 15% of the intertidal zone being rutted after 10 vehicle passes to 85% after 100 passes. A new camera platform, specifically designed for beach surveys, was field tested and the resulting image-based data compared with traditional line-intercept methods and in situ measurements using quadrats. All techniques gave similar results in terms of quantifying the relationship between traffic intensity and beach disturbance. However, the physical, in situ measurements, using quadrats, generally produced higher (+4.68%) estimates than photos taken with the camera platform coupled with off-site image analysis. Image-based methods can be more costly, but in politically and socially sensitive monitoring applications, such as ORV use on sandy beaches, they are superior in providing unbiased and permanent records of environmental conditions in relation to anthropogenic pressures.
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Praias , Monitoramento Ambiental/métodos , Monitoramento Ambiental/estatística & dados numéricos , Modelos Teóricos , Veículos Off-Road/estatística & dados numéricos , QueenslandRESUMO
EBV is associated with the epithelial cancer, nasopharyngeal carcinoma (NPC), and the lymphoid malignancy, Hodgkin lymphoma (HL). The EBV latent membrane proteins 1 and 2A are expressed in these tumors. These proteins activate the phosphatidylinositol 3'-OH kinase (PI3K)/Akt pathway, which is commonly activated inappropriately in malignancy. In this study, the status of Akt activation and its targets, glycogen synthase kinase-3beta (GSK-3beta) and beta-catenin, was investigated in NPC and HL clinical specimens. In the majority of HL and NPC specimens, Akt was activated, indicating an important role for this kinase in the development and/or progression of these tumors. Akt phosphorylates and inactivates GSK-3beta, a negative regulator of the proto-oncoprotein beta-catenin that is aberrantly activated in many cancers. GSK-3beta was phosphorylated and inactivated with concomitant nuclear beta-catenin accumulation in the majority of NPC specimens. The malignant cells of the majority of HL cases, however, did not have inactivated GSK-3beta and lacked nuclear beta-catenin expression. These data indicate that this signaling arm of PI3K/Akt is universal and important in NPC pathogenesis but is apparently not affected in HL. These findings point to a divergence in pathways activated by EBV in different cellular contexts.
Assuntos
Infecções por Vírus Epstein-Barr/metabolismo , Herpesvirus Humano 4/patogenicidade , Doença de Hodgkin/metabolismo , Neoplasias Nasofaríngeas/metabolismo , Transdução de Sinais , Animais , Proteínas do Citoesqueleto/metabolismo , Infecções por Vírus Epstein-Barr/virologia , Quinase 3 da Glicogênio Sintase/antagonistas & inibidores , Quinase 3 da Glicogênio Sintase/metabolismo , Glicogênio Sintase Quinase 3 beta , Doença de Hodgkin/patologia , Doença de Hodgkin/virologia , Humanos , Camundongos , Neoplasias Nasofaríngeas/patologia , Neoplasias Nasofaríngeas/virologia , Fosforilação , Proteínas Serina-Treonina Quinases/metabolismo , Proteínas Proto-Oncogênicas/metabolismo , Proteínas Proto-Oncogênicas c-akt , Transativadores/metabolismo , Transplante Heterólogo , Células Tumorais Cultivadas , Proteínas da Matriz Viral/genética , Proteínas da Matriz Viral/fisiologia , beta CateninaRESUMO
Thyroid cancer incidence has been increasing over time, and it is estimated that â¼1950 advanced thyroid cancer patients will die of their disease in 2015. To combat this disease, an enhanced understanding of thyroid cancer development and progression as well as the development of efficacious, targeted therapies are needed. In vitro and in vivo studies utilizing thyroid cancer cell lines and animal models are critically important to these research efforts. In this report, we detail our studies with a panel of authenticated human anaplastic and papillary thyroid cancer (ATC and PTC) cell lines engineered to express firefly luciferase in two in vivo murine cancer models-an orthotopic thyroid cancer model as well as an intracardiac injection metastasis model. In these models, primary tumor growth in the orthotopic model and the establishment and growth of metastases in the intracardiac injection model are followed in vivo using an IVIS imaging system. In the orthotopic model, the ATC cell lines 8505C and T238 and the PTC cell lines K1/GLAG-66 and BCPAP had take rates >90 % with final tumor volumes ranging 84-214 mm(3) over 4-5 weeks. In the intracardiac model, metastasis establishment was successful in the ATC cell lines HTh74, HTh7, 8505C, THJ-16T, and Cal62 with take rates ≥70 %. Only one of the PTC cell lines tested (BCPAP) was successful in the intracardiac model with a take rate of 30 %. These data will be beneficial to inform the choice of cell line and model system for the design of future thyroid cancer studies.
Assuntos
Modelos Animais de Doenças , Metástase Neoplásica/patologia , Transplante de Neoplasias/métodos , Neoplasias da Glândula Tireoide/patologia , Animais , Linhagem Celular Tumoral , Neoplasias Cardíacas/secundário , Xenoenxertos , Humanos , Camundongos , Camundongos NusAssuntos
Óculos , Testa/cirurgia , Retalhos Cirúrgicos , Humanos , Nariz , Procedimentos de Cirurgia PlásticaRESUMO
Heterogeneity of heart failure (HF) phenotypes indicates contributions from underlying common polymorphisms. We considered polymorphisms in the beta(1)-adrenergic receptor (beta(1)AR), a beta-blocker target, as candidate pharmacogenomic loci. Transfected cells, genotyped human nonfailing and failing ventricles, and a clinical trial were used to ascertain phenotype and mechanism. In nonfailing and failing isolated ventricles, beta(1)-Arg-389 had respective 2.8 +/- 0.3- and 4.3 +/- 2.1-fold greater agonist-promoted contractility vs. beta(1)-Gly-389, defining enhanced physiologic coupling under relevant conditions of endogenous expression and HF. The beta-blocker bucindolol was an inverse agonist in failing Arg, but not Gly, ventricles, without partial agonist activity at either receptor; carvedilol was a genotype-independent neutral antagonist. In transfected cells, bucindolol antagonized agonist-stimulated cAMP, with a greater absolute decrease observed for Arg-389 (435 +/- 80 vs. 115 +/- 23 fmol per well). Potential pathophysiologic correlates were assessed in a placebo-controlled trial of bucindolol in 1,040 HF patients. No outcome was associated with genotype in the placebo group, indicating little impact on the natural course of HF. However, the Arg-389 homozygotes treated with bucindolol had an age-, sex-, and race-adjusted 38% reduction in mortality (P = 0.03) and 34% reduction in mortality or hospitalization (P = 0.004) vs. placebo. In contrast, Gly-389 carriers had no clinical response to bucindolol compared with placebo. Those with Arg-389 and high baseline norepinephrine levels trended toward improved survival, but no advantage with this allele and exaggerated sympatholysis was identified. We conclude that beta(1)AR-389 variation alters signaling in multiple models and affects the beta-blocker therapeutic response in HF and, thus, might be used to individualize treatment of the syndrome.
Assuntos
Antagonistas Adrenérgicos beta/farmacologia , Insuficiência Cardíaca/tratamento farmacológico , Insuficiência Cardíaca/patologia , Polimorfismo Genético , Receptores Adrenérgicos beta 1/genética , Motivos de Aminoácidos , Sequência de Aminoácidos , Animais , Cricetinae , Feminino , Genótipo , Ventrículos do Coração/patologia , Humanos , Masculino , Dados de Sequência Molecular , Farmacogenética/métodos , Propanolaminas/farmacologia , Homologia de Sequência de AminoácidosRESUMO
Epstein-Barr virus (EBV) latent membrane protein 2A (LMP2A) is important for maintenance of latency in infected B lymphocytes. Through its immunoreceptor tyrosine-based activation motif (ITAM) and PY motifs, LMP2A is able to block B-cell receptor (BCR) signaling, bind BCR-associated kinases, and manipulate the turnover of itself and these kinases via a PY-mediated interaction with the Nedd4 family of ubiquitin ligases. In epithelial cells, LMP2A has been shown to activate the phosphatidylinositol 3'-OH kinase/Akt and beta-catenin signaling pathways. In the present study, the biological consequences of LMP2A expression in the normal human foreskin keratinocyte (HFK) cell line were investigated and the importance of the ITAM and PY motifs for LMP2A signaling effects in HFK cells was ascertained. The ITAM was essential for the activation of Akt by LMP2A in HFK cells, while both the ITAM and PY motifs contributed to LMP2A-mediated accumulation and nuclear translocation of the oncoprotein beta-catenin. LMP2A inhibited induction of differentiation in an assay conducted with semisolid methylcellulose medium, and the PY motifs were critical for this inhibition. LMP2A is expressed in the EBV-associated epithelial malignancies nasopharyngeal carcinoma and gastric carcinoma, and these data indicate that LMP2A affects cellular processes that likely contribute to carcinogenesis.
Assuntos
Motivos de Aminoácidos/fisiologia , Proteínas do Citoesqueleto/metabolismo , Células Epiteliais/efeitos dos fármacos , Herpesvirus Humano 4/química , Transativadores/metabolismo , Proteínas da Matriz Viral/farmacologia , Diferenciação Celular/efeitos dos fármacos , Diferenciação Celular/fisiologia , Linhagem Celular Transformada , Células Epiteliais/citologia , Células Epiteliais/virologia , Humanos , Transdução de Sinais/efeitos dos fármacos , Proteínas da Matriz Viral/química , beta CateninaRESUMO
Both insulin and estrogen are well recognized as growth-promoting substances at physiological concentrations, but they function as teratogens at high doses. Both agents can affect alterations in fetal and maternal serum human alpha-fetoprotein (HAFP) levels during pregnancy. In the present study, we have employed animal models of both insulin and estrogen fetotoxicity and teratogenicity in order to study the growth-regulatory properties of HAFP and its derived peptides (HAFP/PEP). We report here the effects of HAFP/PEP on fetotoxicity, congenital malformations, and growth retardation in developing chick and murine fetuses. In the insulin model, HAFP/PEP were effective in reducing both fetal mortality and anatomic anomalies, with the result that growth-retarded fetuses were produced. With HAFP/PEP treatment, fetal demise was reduced by as much as 73 and 63% in murine and chick fetuses, respectively, while fetal anomalies were diminished by 50% during chick development. Genebank searches of identity/similarity in a HAFP/PEP fragment identified matches with a number of proteins associated with glucose, pH, ionic, osmotic, and oxidative stresses, and with heat shock, in addition to stress proteins related to protein folding/unfolding processes. It was proposed that the peptide segment on HAFP may represent a topographic 'hotspot', sensitive to stress/shock conditions, which exhibits a propensity for conformational alteration in the tertiary structure of the fetal protein.