RESUMEN

Aim: Promoter methylation of LINE-1 may be affected by prematurity, but there is little evidence in the literature.Materials & methods: Blood from premature and full-term neonates on days 0, 5, 30 and 90 was analyzed for DNA methylation percentage in a promoter region of the LINE-1, after bisulfite conversion and pyrosequencing.Results: Premature infants, as a whole, showed significantly lower methylation percentage at birth, but this difference diminished over time. However, the subgroup of extremely premature (<28 weeks gestational age) had higher methylation percentages, similar to full-term newborns.Conclusion: This research underscores the critical role of prematurity on the methylation pattern of LINE-1. These findings underline the complexity of epigenetic regulation in prematurity and emphasize the need for further studies.

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Premature birth can have significant effects on a baby's development and long-term health. This study investigates how being born prematurely affects a process called DNA methylation, which can influence how genes are turned on or off. Specifically, we examined the LINE-1 promoter, a frequently occurring region of DNA known for its role in regulating gene activity.We collected blood samples from both premature and full-term newborns at birth and at several points in the early months of life. Our findings showed that premature babies have lower levels of LINE-1 promoter methylation at birth compared with full-term babies. These differences in methylation could possibly affect the babies' development and health as they grow.Our research highlights the need for continued study in this area to explore how these epigenetic changes impact long-term health and to develop strategies to mitigate these effects.

Asunto(s)

Metilación de ADN , Recien Nacido Prematuro , Elementos de Nucleótido Esparcido Largo , Regiones Promotoras Genéticas , Humanos , Recién Nacido , Femenino , Masculino , Epigénesis Genética , Edad Gestacional

RESUMEN

PURPOSE: Retrotransposons play important roles during early development when they are transiently de-repressed during epigenetic reprogramming. Long interspersed element-1 (L1), the only autonomous retrotransposon in humans, comprises 17% of the human genome. We applied the Single Cell Transposon Insertion Profiling by Sequencing (scTIPseq) to characterize and map L1 insertions in human embryos. METHODS: Sixteen cryopreserved, genetically tested, human blastocysts, were accessed from consenting couples undergoing IVF at NYU Langone Fertility Center. Additionally, four trios (father, mother, and embryos) were also evaluated. scTIPseq was applied to map L1 insertions in all samples, using L1 locations reported in the 1000 Genomes as controls. RESULTS: Twenty-nine unknown and unique insertions were observed in the sixteen embryos. Most were intergenic; no insertions were located in exons or immediately upstream of genes. The location or number of unknown insertions did not differ between euploid and aneuploid embryos, suggesting they are not merely markers of aneuploidy. Rather, scTIPseq provides novel information about sub-chromosomal structural variation in human embryos. Trio analyses showed a parental origin of all L1 insertions in embryos. CONCLUSION: Several studies have measured L1 expression at different stages of development in mice, but this study for the first time reports unknown insertions in human embryos that were inherited from one parent, confirming no de novo L1 insertions occurred in parental germline or during embryogenesis. Since one-third of euploid embryo transfers fail, future studies would be useful for understanding whether these sub-chromosomal genetic variants or de novo L1 insertions affect embryo developmental potential.

Asunto(s)

Blastocisto , Elementos de Nucleótido Esparcido Largo , Humanos , Elementos de Nucleótido Esparcido Largo/genética , Blastocisto/metabolismo , Femenino , Embrión de Mamíferos/metabolismo , Desarrollo Embrionario/genética , Mutagénesis Insercional/genética , Aneuploidia , Genoma Humano/genética , Fertilización In Vitro , Masculino , Variación Genética/genética , Ratones , Mapeo Cromosómico/métodos

RESUMEN

Avian genomes are characterized as being more compact than other amniotes, with less diversity and density of transposable elements (TEs). In addition, birds usually show bimodal karyotypes, exhibiting a great variation in diploid numbers. Some species present unusually large sex chromosomes, possibly due to the accumulation of repetitive sequences. Avian retrotransposon-like element (AviRTE) is a long interspersed nuclear element (LINE) recently discovered in the genomes of birds and nematodes, and it is still poorly characterized in terms of chromosomal mapping and phylogenetic relationships. In this study, we mapped AviRTE isolated from the Trogon surrucura genome into the T. surrucura (TSU) karyotype. Furthermore, we analyzed the phylogenetic relationships of this LINE in birds and other vertebrates. Our results showed that the distribution pattern of AviRTE is not restricted to heterochromatic regions, with accumulation on the W chromosome of TSU, yet another species with an atypical sex chromosome and TE hybridization. The phylogenetic analysis of AviRTE sequences in birds agreed with the proposed phylogeny of species in most clades, and allowed the detection of this sequence in other species, expanding the distribution of the element.

Asunto(s)

Aves , Mapeo Cromosómico , Cariotipo , Filogenia , Retroelementos , Cromosomas Sexuales , Animales , Aves/genética , Aves/clasificación , Cromosomas Sexuales/genética , Masculino , Femenino , Elementos de Nucleótido Esparcido Largo

RESUMEN

Currently, the marketing of electronic cigarettes as a safe alternative to smoking has increased, which is associated with greater use of these devices, especially among young people and smokers interested in quitting tobacco cigarettes. Given the growing use of this type of product, there is a need to determine the consequences of electronic cigarettes on human health, especially since many of the compounds contained in the aerosol and liquid of these devices have a high potential to be carcinogenic and genotoxic. Additionally, many of these compounds' aerosol concentrations exceed the safe limits. We have evaluated the levels of genotoxicity and changes in DNA methylation patterns associated with vaping. We analyzed a total of 90 peripheral blood samples from a population of vapers (n = 32), smokers (n = 18), and controls (n = 32), in which the frequencies of genotoxicity were determined by the cytokinesis-blocking micronuclei (CBMN) assay and the patterns of methylation of the repetitive elements of LINE-1 through the Quantitative Methylation Specific PCR (qMSP) assay. Here we show an increase in genotoxicity levels associated with vaping habits. Additionally, the group of vapers showed changes at the epigenetic level specifically associated with the loss of methylation of the LINE-1 elements. These changes in LINE-1 methylation patterns were reflected in its representative RNA expression detected in vapers.

Asunto(s)

Sistemas Electrónicos de Liberación de Nicotina , Humanos , Adolescente , Metilación de ADN , Elementos de Nucleótido Esparcido Largo , Fumar , Aerosoles

RESUMEN

BACKGROUND: Long interspersed element 1 (LINE-1 or L1) retrotransposons are mobile elements that constitute 17-20% of the human genome. Strong correlations between abnormal L1 expression and several human diseases have been reported. This has motivated increasing interest in accurate quantification of the number of L1 copies present in any given biologic specimen. A main obstacle toward this aim is that L1s are relatively long DNA segments with regions of high variability, or largely present in the human genome as truncated fragments. These particularities render traditional alignment strategies, such as seed-and-extend inefficient, as the number of segments that are similar to L1s explodes exponentially. This study uses the pattern matching methodology for more accurate identification of L1s. We validate experimentally the superiority of pattern matching for L1 detection over alternative methods and discuss some of its potential applications. RESULTS: Pattern matching detected full-length L1 copies with high precision, reasonable computational time, and no prior input information. It also detected truncated and significantly altered copies of L1 with relatively high precision. The method was effectively used to annotate L1s in a target genome and to calculate copy number variation with respect to a reference genome. Crucial to the success of implementation was the selection of a small set of k-mer probes from a set of sequences presenting a stable pattern of distribution in the genome. As in seed-and-extend methods, the pattern matching algorithm sowed these k-mer probes, but instead of using heuristic extensions around the seeds, the analysis was based on distribution patterns within the genome. The desired level of precision could be adjusted, with some loss of recall. CONCLUSION: Pattern matching is more efficient than seed-and-extend methods for the detection of L1 segments whose characterization depends on a finite set of sequences with common areas of low variability. We propose that pattern matching may help establish correlations between L1 copy number and disease states associated with L1 mobilization and evolution.

Asunto(s)

Variaciones en el Número de Copia de ADN , Genoma Humano , Humanos , Elementos de Nucleótido Esparcido Largo/genética , Retroelementos

RESUMEN

This study aimed to understand the impact of LINE-1 and SINE-B1 retroelements on the architecture and karyotypic diversification of five rodent species of the genus Proechimys from different regions of the Amazon. Karyotype comparisons were performed using fluorescent interspecific in situ hybridization. The L1 and B1 retroelements showed a non-random arrangement and a conserved pattern when the genomes of the five species of Proechimys were compared, including the two cytotypes of Proechimys guyannensis The signal homeology among the chromosomes and the degree of similarity among the formed clusters indicate rearrangements such as fusion/fission, and demonstrates that these retroelements can behave as derived characters shared in Proechimys The differentiated distribution and organization of these retroelements in the karyotypes and in the chromosomal fiber, respectively, may represent a strong indication of their role as generating sources of karyotypic diversity in the genus Proechimys and provide insights into the evolutionary relationships between taxa.

Asunto(s)

Retroelementos , Roedores , Animales , Cromosomas , Elementos de Nucleótido Esparcido Largo/genética , Retroelementos/genética , Roedores/genética

RESUMEN

Down syndrome (DS) is the most common chromosomal disorder, resulting from the failure of normal chromosome 21 segregation. Studies have suggested that impairments within the one-carbon metabolic pathway can be of relevance for the global genome instability observed in mothers of individuals with DS. Based on the association between global DNA hypomethylation, genome instability, and impairments within the one-carbon metabolic pathway, the present study aimed to identify possible predictors, within the one-carbon metabolism, of global DNA methylation, measured by methylation patterns of LINE-1 and Alu repetitive sequences, in mothers of individuals with DS and mothers of individuals without the syndrome. In addition, we investigated one-carbon genetic polymorphisms and metabolites as maternal predisposing factors for the occurrence of trisomy 21 in children. Eighty-three samples of mothers of children with DS with karyotypically confirmed free trisomy 21 (case group) and 84 of mothers who had at least one child without DS or any other aneuploidy were included in the study. Pyrosequencing assays were performed to access global methylation. The results showed that group affiliation (case or control), betaine-homocysteine methyltransferase (BHMT) G742A and transcobalamin 2 (TCN2) C776G polymorphisms, and folate concentration were identified as predictors of global Alu DNA methylation values. In addition, thymidylate synthase (TYMS) 28-bp repeats 2R/3R or 3R/3R genotypes are independent maternal predisposing factors for having a child with DS. This study adds evidence that supports the association of impairments in the one-carbon metabolism, global DNA methylation, and the possibility of having a child with DS.

Asunto(s)

Carbono/metabolismo , Metilación de ADN/genética , Síndrome de Down/genética , Síndrome de Down/metabolismo , Estudio de Asociación del Genoma Completo , Inestabilidad Genómica/genética , Relaciones Madre-Hijo , Madres , Adolescente , Adulto , Anciano , Elementos Alu/genética , Betaína-Homocisteína S-Metiltransferasa/genética , Betaína-Homocisteína S-Metiltransferasa/metabolismo , Femenino , Ácido Fólico/metabolismo , Predisposición Genética a la Enfermedad/genética , Humanos , Elementos de Nucleótido Esparcido Largo/genética , Masculino , Persona de Mediana Edad , Polimorfismo Genético , Transducción de Señal/genética , Transducción de Señal/fisiología , Timidilato Sintasa/genética , Transcobalaminas/genética , Transcobalaminas/metabolismo , Adulto Joven

RESUMEN

Aim: We investigated GRIN1, GRIN2A, GRIN2B and LINE-1 DNA methylation in first-episode schizophrenia patients, their nonaffected siblings and age- and sex-matched controls testing for associations between DNA methylation and exposition to childhood trauma. Materials & methods: The Childhood Trauma Questionnaire evaluated the history of childhood trauma. Genomic DNA was bisulfite converted and pyrosequencing was employed to quantify DNA methylation. Results:GRIN2A, GRIN2B and LINE-1 DNA methylation was not associated with childhood trauma in patients, siblings and controls. Siblings with childhood trauma had hypermethylation at CpG1 of GRIN1 compared with siblings without trauma. Conclusion: Childhood trauma may influence GRIN1 methylation in subjects with liability to psychosis, but not in frank schizophrenia or controls.

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Lay abstract Schizophrenia results from a combination of genetic and environmental influences. We investigated how some changes in genes can be silenced by a process named DNA methylation and may be linked to schizophrenia. For this reason, we hypothesized that childhood trauma, an environmental risk factor, would be associated with DNA methylation in schizophrenia patients compared with their unaffected siblings and controls. Our research has shown that altered blood DNA methylation of one candidate gene for psychiatric disorders may be associated with childhood trauma in the unaffected siblings of schizophrenia patients, but not in frank schizophrenia or controls. We believe that this gene plays an important role in helping identify vulnerable as well as resilient individuals to schizophrenia disorder.

Asunto(s)

Experiencias Adversas de la Infancia , Susceptibilidad a Enfermedades , Receptores de N-Metil-D-Aspartato/genética , Esquizofrenia/epidemiología , Esquizofrenia/etiología , Adolescente , Adulto , Biomarcadores , Estudios de Casos y Controles , Islas de CpG , Metilación de ADN , Femenino , Regulación de la Expresión Génica , Humanos , Elementos de Nucleótido Esparcido Largo , Masculino , Persona de Mediana Edad , Receptores de N-Metil-D-Aspartato/metabolismo , Medición de Riesgo , Factores de Riesgo , Esquizofrenia/diagnóstico , Hermanos , Adulto Joven

RESUMEN

Alterations of global DNA methylation have been evaluated in several studies worldwide; however, Long Interspersed Nuclear Elements-1 (LINE-1) methylation in genetically conserved populations such as indigenous communities have not, to our knowledge, been reported. The aim of this study was to evaluate the relationship between LINE-1 methylation patterns and factors such as pesticide exposure and socio-cultural characteristics in the Indigenous Huichol Population of Nayarit, Mexico. A cross-sectional study was conducted in 140 Huichol indigenous individuals. A structured questionnaire was used to determine general and anthropometric characteristics, diet, harmful habits, and pesticide exposure. DNA methylation was determined by pyrosequencing of bisulfite-treated DNA. A lower level of LINE-1 methylation was found in the indigenous population when compared to a Mestizo population previously studied by our group. This difference might be due to the influence of the genetic admixture and differing dietary and lifestyle habits. The males in the indigenous population exhibited increased LINE-1 methylation in comparison to the females. Sex and alcohol consumption showed positive associations with LINE-1 methylation, while weight, current work in the field, current pesticide usage, and folate intake exhibited negative associations with LINE-1 methylation. The results suggest that ethnicity, as well as other internal and environmental factors, might influence LINE-1 methylation.

Asunto(s)

Metilación de ADN , Grupos de Población , Estudios Transversales , Femenino , Humanos , Elementos de Nucleótido Esparcido Largo/genética , Masculino , México

RESUMEN

PURPOSE: In contrast to hormone receptor driven breast cancer, patients presenting with triple-negative breast cancer (TNBC) often have limited drug treatment options. Efavirenz, a non-nucleoside reverse transcriptase (RT) inhibitor targets abnormally overexpressed long interspersed nuclear element 1 (LINE-1) RT and has been shown to be a promising anticancer agent for treating prostate and pancreatic cancers. However, its effectiveness in treating patients with TNBC has not been comprehensively examined. METHODS: In this study, the effect of Efavirenz on several TNBC cell lines was investigated by examining several cellular characteristics including viability, cell division and death, changes in cell morphology as well as the expression of LINE-1. RESULTS: The results show that in a range of TNBC cell lines, Efavirenz causes cell death, retards cell proliferation and changes cell morphology to an epithelial-like phenotype. In addition, it is the first time that a whole-genome RNA sequence analysis has identified the fatty acid metabolism pathway as a key regulator in this Efavirenz-induced anticancer process. CONCLUSION: In summary, we propose Efavirenz is a potential anti-TNBC drug and that its mode of action can be linked to the fatty acid metabolism pathway.

Asunto(s)

Alquinos/uso terapéutico , Antineoplásicos/uso terapéutico , Benzoxazinas/uso terapéutico , Ciclopropanos/uso terapéutico , Elementos de Nucleótido Esparcido Largo , Inhibidores de la Transcriptasa Inversa/uso terapéutico , Neoplasias de la Mama Triple Negativas/tratamiento farmacológico , Muerte Celular , Línea Celular Tumoral , Proliferación Celular/efectos de los fármacos , Forma de la Célula/efectos de los fármacos , Regulación hacia Abajo , Ácidos Grasos/metabolismo , Femenino , Humanos , Fenotipo , Transcriptoma , Neoplasias de la Mama Triple Negativas/genética , Neoplasias de la Mama Triple Negativas/patología

RESUMEN

Aim: To evaluate the risk of nonsyndromic orofacial clefts (NSOFCs) associated with LINE-1 methylation, as a marker of global DNA methylation, and the effect of MTHFR functional variants on this variable. Patients & methods: LINE-1 methylation was evaluated by bisulfite modification coupled to DNA pyrosequencing in 95 NSOFC cases and 95 controls. In these subjects, MTHFR genotypes for variants c.C677T (rs1801133) and c.A1298C (rs1801131) were obtained. Results: Middle levels (second tertile) of LINE-1 methylation increase the risk of NSOFCs. In addition, LINE-1 methylation depends on c.A1298C genotypes in controls but not in cases. Conclusion: A nonlinear association between global DNA methylation and NSOFCs was detected in this Chilean population, which appears to be influenced by MTHFR functional variants.

Asunto(s)

Encéfalo/anomalías , Labio Leporino/genética , Fisura del Paladar/genética , Metilación de ADN , Elementos de Nucleótido Esparcido Largo , Metilenotetrahidrofolato Reductasa (NADPH2)/genética , Adolescente , Estudios de Casos y Controles , Niño , Preescolar , Chile , Humanos , Lactante , Recién Nacido , Polimorfismo de Nucleótido Simple

RESUMEN

PURPOSE: Construction workers are exposed to a mixture of substances in the workplace considered carcinogenic. This study aimed to characterise gene-specific changes in DNA methylation over the workweek in this population as this type of environmental exposure has not been studied extensively. MATERIALS AND METHODS: We evaluated their DNA methylation in 4 gene-promoter regions (CDKN2A, RASSF1A, MLH1 and APC) and 2 repeat elements (ALU and LINE-1) in blood samples obtained on the first and fifth day of the same workweek of a group of 39 male construction workers. DNA methylation was measured by bisulphite-PCR-Pyrosequencing. We also measured the levels of trace elements in the whole blood by ICP-MS. RESULTS: Only the CDKN2A gene had significant differences in the average methylation level between the first and fifth day of the workweek. We also observed that the levels of Cu, Pb, Se, Mn, and Ti decreased during the fifth day of exposure, and only lead, titanium and copper showed a low significant correlation with the methylation level mean for three specific CpG sites of the CDKN2A. CONCLUSIONS: In summary, the data suggest that altered levels of CDKN2A methylation in construction workers may be a potential biomarker of recent exposure in this environment.

Asunto(s)

Inhibidor p16 de la Quinasa Dependiente de Ciclina/genética , Metilación de ADN/genética , Epigénesis Genética , Exposición Profesional/efectos adversos , Adulto , Elementos Alu/genética , Biomarcadores/sangre , Industria de la Construcción , Humanos , Elementos de Nucleótido Esparcido Largo/genética , Masculino , Homólogo 1 de la Proteína MutL/genética , Regiones Promotoras Genéticas/genética , Proteínas Supresoras de Tumor/genética

RESUMEN

Long INterspersed Elements-1 (L1s) constitute >17% of the human genome and still actively transpose in it. Characterizing L1 transposition across the genome is critical for understanding genome evolution and somatic mutations. However, to date, L1 insertion and fixation patterns have not been studied comprehensively. To fill this gap, we investigated three genome-wide data sets of L1s that integrated at different evolutionary times: 17,037 de novo L1s (from an L1 insertion cell-line experiment conducted in-house), and 1,212 polymorphic and 1,205 human-specific L1s (from public databases). We characterized 49 genomic features-proxying chromatin accessibility, transcriptional activity, replication, recombination, etc.-in the ±50 kb flanks of these elements. These features were contrasted between the three L1 data sets and L1-free regions using state-of-the-art Functional Data Analysis statistical methods, which treat high-resolution data as mathematical functions. Our results indicate that de novo, polymorphic, and human-specific L1s are surrounded by different genomic features acting at specific locations and scales. This led to an integrative model of L1 transposition, according to which L1s preferentially integrate into open-chromatin regions enriched in non-B DNA motifs, whereas they are fixed in regions largely free of purifying selection-depleted of genes and noncoding most conserved elements. Intriguingly, our results suggest that L1 insertions modify local genomic landscape by extending CpG methylation and increasing mononucleotide microsatellite density. Altogether, our findings substantially facilitate understanding of L1 integration and fixation preferences, pave the way for uncovering their role in aging and cancer, and inform their use as mutagenesis tools in genetic studies.

Asunto(s)

Evolución Biológica , Elementos Transponibles de ADN , Genoma Humano , Elementos de Nucleótido Esparcido Largo , Modelos Genéticos , Humanos , Mutagénesis Insercional

RESUMEN

Aim: We investigated the DNA methylation profile over LINE-1 in antipsychotic-naive, first-episode psychosis-patients (n = 69) before and after 2 months of risperidone treatment and in healthy controls (n = 62). Materials & methods: Patients were evaluated using standardized scales and classified as responders and nonresponders. DNA from blood was bisulfite converted and LINE-1 fragments were amplified and pyrosequencing was performed. Results: Lower LINE-1 methylation was observed in antipsychotic-naive first-episode psychosis patients than in healthy controls. Lower DNA methylation levels before treatment were associated with poor risperidone responses. A positive correlation was observed between LINE-1 methylation levels and positive symptoms response. Conclusion: Our study brings new insight regarding how epigenomic studies and clinical correlation studies can supplement psychosis treatment.

Asunto(s)

Antipsicóticos/uso terapéutico , Metilación de ADN , Elementos de Nucleótido Esparcido Largo , Trastornos Psicóticos/tratamiento farmacológico , Risperidona/uso terapéutico , Adolescente , Adulto , Estudios de Casos y Controles , Femenino , Humanos , Masculino , Trastornos Psicóticos/genética , Resultado del Tratamiento , Adulto Joven

RESUMEN

Long interspersed nuclear elements-1 (LINE-1) are mobile DNA elements that comprise the majority of interspersed repeats in the mammalian genome. During the last decade, these transposable sequences have been described as controlling elements involved in transcriptional regulation and genome plasticity. Recently, LINE-1 have been implicated in neurogenesis, but to date little is known about their nuclear organization in neurons. The olfactory epithelium is a site of continuous neurogenesis, and loci of olfactory receptor genes are enriched in LINE-1 copies. Olfactory neurons have a unique inverted nuclear architecture and constitutive heterochromatin forms a block in the center of the nuclei. Our DNA FISH images show that, even though LINE-1 copies are dispersed throughout the mice genome, they are clustered forming a cap around the central heterochromatin block and frequently occupy the same position as facultative heterochromatin in olfactory neurons nuclei. This specific LINE-1 organization could not be observed in other olfactory epithelium cell types. Analyses of H3K27me3 and H3K9me3 ChIP-seq data from olfactory epithelium revealed that LINE-1 copies located at OR gene loci show different enrichment for these heterochromatin marks. We also found that LINE-1 are transcribed in mouse olfactory epithelium. These results suggest that LINE-1 play a role in the olfactory neurons' nuclear architecture. SIGNIFICANCE STATEMENT: LINE-1 are mobile DNA elements and comprise almost 20% of mice and human genomes. These retrotransposons have been implicated in neurogenesis. We show for the first time that LINE-1 retrotransposons have a specific nuclear organization in olfactory neurons, forming aggregates concentric to the heterochromatin block and frequently occupying the same region as facultative heterochromatin. We found that LINE-1 at olfactory receptor gene loci are differently enriched for H3K9me3 and H3K27me3, but LINE-1 transcripts could be detected in the olfactory epithelium. We speculate that these retrotransposons play an active role in olfactory neurons' nuclear architecture.

Asunto(s)

Elementos de Nucleótido Esparcido Largo/fisiología , Mucosa Olfatoria/metabolismo , Neuronas Receptoras Olfatorias/metabolismo , Receptores Odorantes/metabolismo , Animales , Núcleo Celular/metabolismo , Regulación de la Expresión Génica/fisiología , Heterocromatina/metabolismo , Histonas/metabolismo , Masculino , Ratones Endogámicos C57BL , Receptores Odorantes/genética

RESUMEN

Breast cancer is the most common cancer type in females worldwide. Environmental exposure to pesticides affecting hormonal homeostasis does not necessarily induce DNA mutations but may influence gene expression by disturbances in epigenetic regulation. Expression of long interspersed nuclear element-1 (LINE-1) has been associated with tumorigenesis in several cancers. In nearly all somatic cells, LINE-1 is silenced by DNA methylation in the 5́'UTR and reactivated during disease initiation and/or progression. Strong ligands of aryl hydrocarbon receptor (AhR) activate LINE-1 through the transforming growth factor-ß1 (TGF-ß1)/Smad pathway. Hexachlorobenzene (HCB) and chlorpyrifos (CPF), both weak AhR ligands, promote cell proliferation and migration in breast cancer cells, as well as tumor growth in rat models. In this context, our aim was to examine the effect of these pesticides on LINE-1 expression and ORF1p localization in the triple-negative breast cancer cell line MDA-MB-231 and the non-tumorigenic epithelial breast cell line NMuMG, and to evaluate the role of TGF-ß1 and AhR pathways. Results show that 0.5 µM CPF and 0.005 µM HCB increased LINE-1 mRNA expression through Smad and AhR signaling in MDA-MB-231. In addition, the methylation of the first sites in 5́'UTR of LINE-1 was reduced by pesticide exposure, although the farther sites remained unaffected. Pesticides modulated ORF1p localization in MDA-MB-231: 0.005 µM HCB and 50 µM CPF increased nuclear translocation, while both induced cytoplasmic retention at 0.5 and 5 µM. Moreover, both stimulated double-strand breaks, enhancing H2AX phosphorylation, coincidentally with ORF1p nuclear localization. In NMuMG similar results were observed, since they heighten LINE-1 mRNA levels. CPF effect was through AhR and TGF-ß1 signaling, whereas HCB action depends only of AhR. In addition, both pesticides increase ORF1p expression and nuclear localization. Our results provide experimental evidence that HCB and CPF exposure modify LINE-1 methylation levels and induce LINE-1 reactivation, suggesting that epigenetic mechanisms could contribute to pesticide-induced breast cancer progression.

Asunto(s)

Factores de Transcripción con Motivo Hélice-Asa-Hélice Básico/metabolismo , Células Epiteliales/metabolismo , Elementos de Nucleótido Esparcido Largo/fisiología , Receptores de Hidrocarburo de Aril/metabolismo , Retroelementos/fisiología , Neoplasias de la Mama Triple Negativas/metabolismo , Línea Celular Tumoral , Relación Dosis-Respuesta a Droga , Células Epiteliales/efectos de los fármacos , Células Epiteliales/patología , Femenino , Hexaclorobenceno/metabolismo , Hexaclorobenceno/toxicidad , Humanos , Ligandos , Elementos de Nucleótido Esparcido Largo/efectos de los fármacos , Retroelementos/efectos de los fármacos , Neoplasias de la Mama Triple Negativas/patología

RESUMEN

Childhood obesity is a global burden affecting millions of children worldwide. It is well-known that the adiposity profile in children is critical for future occurrence of diseases. As a multifactorial disease, obesity is associated with genetic and environmental factors. Epigenetic mechanisms link the plethora of environmental clues to a given phenotype. DNA methylation is the most studied epigenetic mark and its importance in several diseases was acknowledged. In childhood obesity, specifically, the studies show a consistent association between adiposity and methylation at the gene and genome-wide scales. The relationship between DNA methylation and childhood obesity has been proved strong for some genes and pathways. However, the studies are heterogeneous in their design, methodologies, and results. The aim of this review is to discuss this heterogeneity and point out some aspects that should be considered in future studies to clarify the role of DNA methylation in childhood obesity.

Asunto(s)

Metilación de ADN , Epigénesis Genética , Predisposición Genética a la Enfermedad , Obesidad Infantil/genética , Proteínas Reguladoras de la Apoptosis/genética , Niño , Estudios Transversales , Epigenoma , Epigenómica , Genoma Humano , Estudio de Asociación del Genoma Completo , Humanos , Factor II del Crecimiento Similar a la Insulina/genética , Leptina/genética , Elementos de Nucleótido Esparcido Largo , Estudios Longitudinales , PPAR gamma/genética , Receptores de Leptina/genética , Proteínas Represoras/genética

RESUMEN

CONTEXT: Androgen insensitivity syndrome (AIS) is the most common cause of disorders of sex development in 46,XY individuals. It is an X-linked condition usually caused by pathogenic allelic variants in the androgen receptor (AR) gene. The phenotype depends on the AR variant, ranging from severe undervirilization (complete AIS) to several degrees of external genitalia undervirilization. Although 90% of those with complete AIS will have AR mutations, this will only be true for 40% of those with partial AIS (PAIS). OBJECTIVE: To identify the genetic etiology of AIS in a large multigenerational family with the PAIS phenotype. PARTICIPANTS: Nine affected individuals with clinical and laboratory findings consistent with PAIS and a normal exonic AR sequencing. SETTINGS: Endocrine clinic and genetic institute from two academic referral centers. DESIGN: Analysis of whole exons of the AR gene, including splicing regions, was performed, followed by sequencing of the 5'untranslated region (UTR) of the AR gene. Detailed phenotyping was performed at the initial diagnosis and long-term follow-up, and circulating levels of steroid gonadal hormones were measured in all affected individuals. AR expression was measured using RT-PCR and cultured fibroblasts. RESULTS: All 46,XY family members with PAIS had inherited, in hemizygosity, a complex defect (∼1100 bp) in the 5'UTR region of the AR surrounded by a duplicated 18-bp sequence (target site duplication). This sequence is 99.7% similar to an active, long, interspersed element present on the X chromosome (AC002980; Xq22.2), which was inserted in the 5'UTR of the AR gene, severely reducing AR expression and leading to PAIS. CONCLUSION: The molecular diagnosis of PAIS remains challenging. The genomic effect of retrotransposon mobilization should be considered a possible molecular cause of AIS and other AR diseases.

Asunto(s)

Síndrome de Resistencia Androgénica/etiología , Cromosomas Humanos X/genética , Elementos de Nucleótido Esparcido Largo/genética , Mutación , Receptores Androgénicos/genética , Adolescente , Adulto , Síndrome de Resistencia Androgénica/patología , Niño , Preescolar , Femenino , Estudios de Seguimiento , Humanos , Lactante , Masculino , Linaje , Fenotipo , Pronóstico

RESUMEN

Cardiovascular risk associated with fetal growth restriction (FGR) could result from an early impaired vascular function. However, whether this effect results in premature vascular aging has not been addressed. We studied the ex vivo reactivity of carotid and femoral arteries in fetal (near term), adults (eight months-old) and aged (16 months-old) guinea pigs in normal (control) and FGR offspring. Additionally, an epigenetic marker of vascular aging (i.e., LINE-1 DNA methylation) was evaluated in human umbilical artery endothelial cells (HUAEC) from control and FGR subjects. Control guinea pig arteries showed an increased contractile response (KCl-induced) and a progressive impairment of NO-mediated relaxing responses as animals get older. FGR was associated with an initial preserved carotid artery reactivity as well as a later significant impairment in NO-mediated responses. Femoral arteries from FGR fetuses showed an increased contractility but a decreased relaxing response compared with control fetuses, and both responses were impaired in FGR-adults. Finally, FGR-HUAEC showed decreased LINE-1 DNA methylation compared with control-HUAEC. These data suggest that the aging of vascular function occurs by changes in NO-mediated responses, with limited alterations in contractile capacity. Further, these effects are accelerated and imposed at early stages of development in subjects exposed to a suboptimal intrauterine environment.

Asunto(s)

Envejecimiento/patología , Endotelio Vascular/crecimiento & desarrollo , Retardo del Crecimiento Fetal/patología , Animales , Arterias Carótidas/crecimiento & desarrollo , Arterias Carótidas/patología , Arterias Carótidas/fisiopatología , Células Cultivadas , Metilación de ADN , Endotelio Vascular/metabolismo , Endotelio Vascular/patología , Femenino , Arteria Femoral/crecimiento & desarrollo , Arteria Femoral/patología , Arteria Femoral/fisiopatología , Retardo del Crecimiento Fetal/genética , Cobayas , Humanos , Elementos de Nucleótido Esparcido Largo/genética , Óxido Nítrico/metabolismo , Vasoconstricción , Vasodilatación

RESUMEN

STUDY OBJECTIVES: Sleep deprivation and low sleep quality are widespread among adolescents, and associate with obesity risk. Plausible mediators include diet and physical activity. Another potential interrelated pathway, as yet unexplored in adolescents, could involve epigenetic modification of metabolism genes. METHODS: In a cohort of 351 Mexico City adolescents (47% male; mean [SD] age = 14 [2] years), 7-day actigraphy was used to assess average sleep duration, sleep fragmentation, and movement index. DNA isolated from blood leukocytes was bisulfite-converted, amplified, and pyrosequenced at four candidate regions. Linear mixed models evaluated sex-stratified associations between sleep characteristics (split into quartiles [Q]) and DNA methylation of each region, adjusted for potential confounders. RESULTS: Mean sleep duration was 8.5 [0.8] hours for boys and 8.7 [1] hours for girls. There were sex-specific associations between sleep duration and LINE-1 (long interspersed nuclear element) methylation. Boys with longer sleep duration (Q4) had lower LINE-1 methylation than boys in the 3rd quartile reference category, while girls with both longer and shorter sleep duration had higher LINE-1 methylation compared to Q3. Longer sleep duration was associated with higher H19 methylation among girls (comparing highest to third quartile, -0.9% [-2.2, 0.5]; p, trend = 0.047). Sleep fragmentation was inversely associated with peroxisome proliferator-activated receptor alpha (PPARA) methylation among girls (comparing highest to lowest fragmentation quartile, 0.9% [0.1 to 1.8]). Girls also showed an inverse association between sleep fragmentation and hydroxysteroid (11-beta) dehydrogenase 2 (HSD11B2; Q4 to Q1, 0.6% [-1.2%, 0%]). CONCLUSIONS: Sleep duration and fragmentation in adolescents show sex-specific associations with leukocyte DNA methylation patterns of metabolism genes.

Asunto(s)

Metilación de ADN/genética , ADN/metabolismo , Epigénesis Genética/genética , Privación de Sueño/genética , Sueño/fisiología , Actigrafía , Adolescente , Dieta , Ejercicio Físico , Femenino , Humanos , Leucocitos/metabolismo , Elementos de Nucleótido Esparcido Largo/genética , Masculino , México , Obesidad/metabolismo , Privación de Sueño/metabolismo , Factores de Tiempo