Mecanismos epigenéticos e controle da expressão do gene HLA-G

Orientador: Maria da Graça BicalhoMonografia (Bacharelado) - Universidade Federal do Paraná. Setor de Ciências Biológicas. Curso de Graduação em Ciências BiológicasResumo : O gene HLA-G faz parte do Complexo Principal de Histocompatibilidade (MHC) e encontra-se no cromossomo 6, na posição 6p21.3. Ele apresenta uma distribuição tecidual restrita e possui funções relacionadas à supressão da resposta imune através da interação da proteína HLA-G com receptores inibitórios presentes nas células Natural Killer (NK) e linfócitos T. Um dos principais papéis atribuídos à HLA-G tem sido a indução da tolerância imunológica materna ao feto semi-alogênico no processo gestacional. Além disso, em situações patológicas tais como, células neoplásicas, transformadas ou infectadas por vírus, sua expressão tem sido considerada uma estratégia, ou mecanismo de escape ao sistema imune do hospedeiro. O controle da expressão de HLA-G ocorre via elementos em cis presentes em sua região promotora/reguladora quando interagem com fatores transcricionais e proteínas ativadoras/inibidoras de reguladores (elementos de ação trans) e acontece tanto em nível trascricional como traducional. Além disso, eventos epigenéticos podem ocorrer em ambos os níveis. Epigenética envolve o estudo de mudanças na expressão gênica sem que ocorram mudanças na sequência de DNA. Os principais eventos epigenéticos são: a metilação das citosinas (C) adjacentes às guaninas (G) na fita do DNA; modificações pós-traducionais da cauda das histonas e, controle da expressão do gene por associação do RNAm a microRNAs. O gene HLA-G está sujeito a todas essas formas de controle da expressão gênica de forma interativa. Neste trabalho ilustramos algumas influências dos eventos epigenéticos na expressão do HLA-G e, mostramos que variações nucleotídicas presentes nos alelos de HLA-G podem exercer grande influência no controle da sua expressão, quaisquer que sejam os mecanismos atuantes

Polimorfismo ins/del 14pb, alelos do gene HLA-G, expressão de sHLA-G e neoplasia intra-epitelial cervical de graus ll(NICll) e III (NICIII)

Orientadora : Profª Drª Maria da Graça BicalhoDissertação (mestrado) - Universidade Federal do Paraná, Setor de Ciências Biológicas, Programa de Pós-Graduação em Genética. Defesa: Curitiba, 27/02/2012Inclui bibliografiaResumo: O cancer cervical (CC) e o segundo cancer que mais afeta mulheres no mundo todo, ele progride a partir de lesoes no cervix uterino causadas pelo virus HPV, estas lesoes sao denominadas neoplasias intraepiteliais cervicais (NIC). As NICs são classificadas em lesao e baixo grau (NIC I) e lesoes de alto grau (NIC II e III). O desenvolvimento do CC depende da persistencia do virus no organismo e esta persistencia esta diretamente relacionada com a eficiencia da resposta imune contra as celulas infectadas. O antigeno leucocitario humano (HLA)-G e um gene HLA de classe I nao classico que apresenta um papel imunorregulatorio. Ele e capaz de inibir a resposta imune quando interage com receptores inibitorios presentes nas celulas Natural Killer e em Linfocitos T. A proteina HLA-G pode ser expressa na forma ligada a membrana celular, ou soluvel (sHLA-G). A expressao de HLA-G ja foi relacionada com diversas patologias e diferentes tipos de canceres como uma estrategia de escape do sistema imune. Neste estudo o objetivo foi investigar a associacao de polimorfismos do gene HLA-G e sua expressao soluvel com o desenvolvimento de lesoes cervicais. A amostra constitui de 100 mulheres diagnosticadas com NIC II, 101 NIC III, e 106 mulheres saudaveis, negativas para NIC. Foi feito a tipagem alelicas para o gene HLA-G e para o polimorfismo de 14 pb presente no exon 8 deste gene; alem disso foi realizada a quantificacao serica de sHLA-G. Nao foi registrada associacao entre a frequencia dos alelos identificados na amostra, ou do polimorfismo de 14 pb e a quantificacao de sHLA-G com predisposicao ou protecao ao desenvolvimento de lesoes cervicais. Tambem nao foi possivel definir associacoes entre os niveis sericos de sHLA-G com os alelos, ou com a presenca ou ausencia dos 14 pb. Palavras chave: HLA-G, sHLA-G, HPV, NIC e cancer cervical.Abstract: Cervical cancer (CC) is the second cancer that most affects women worldwide, it progresses from lesions in the uterine cervix caused by HPV virus, these lesions are called cervical intraepithelial neoplasia (CIN). CINs are classified in low-grade (CIN I) and high-grade lesions (CIN II and III). The development of the CC depends on the persistence of the virus in the body and this persistence is directly related to the efficiency of the immune response against infected cells. Human leukocyte antigen (HLA)-G is an HLA class I non-classic that presents an immunoregulatory role. It is able to inhibit the immune response when interacting with inhibitory receptors present on natural killer cells and T lymphocytes The HLA-G protein can be expressed in the membrane bound form, or soluble (sHLA-G). The expression of HLA-G has been associated with several diseases and different types of cancers as a strategy to escape from the immune system. In this study the aim was to investigate the association of polymorphisms of the HLA-G gene and its soluble expression with the development of cervical lesions. The sample consisted of 100 women diagnosed with CIN II, 101 with CIN III, and 106 healthy women negative for CIN. Allele typing for the gene HLA-G and for the 14 bp polymorphism present in exon 8 of this gene was done, also serum sHLA-G was quantified. No association was recorded between the frequency of the alleles identified in the sample, or 14 bp polymorphism and quantification of sHLA-G with predisposition or protection to the development of cervical lesions. Nor was it possible to define associations between serum levels of sHLA-G with the alleles, or the presence or absence of 14 bp. Keywords: HLA-G, sHLA-G, HPV, NIC and cervical cancer

Case–control study of HLA-G promoter methylation status, HPV infection and cervical neoplasia in Curitiba, Brazil: a pilot analysis

BACKGROUND: The causal association between persistent human papillomavirus (HPV) infection and cervical cancer has been established, but the mechanisms that favor HPV persistence in cervical cells are still unknown. The diminished capability of the immune system to control and resolve HPV infection is one of several hypotheses. The tolerogenic protein HLA-G has shown aberrant expression in a variety of cancers, which has been suggested as a mechanism for tumor escape from immunosurveillance. In the present study we evaluate the role of epigenetic modification (promoter de-methylation) of the HLA-G gene on susceptibility to HPV infection and development of high-grade cervical lesions. METHODS: A case–control study was carried out in Curitiba, Brazil, between February and June 2010. A total of 789 women aged 15–47 years were recruited: 510 controls with normal cervical cytology, and 279 cases with histologically confirmed cervical intraepithelial neoplasia grade 2 (CIN2, N = 150) or grade 3 (CIN3, N = 129). All women were administered a questionnaire by interview, which collected information on demographic and lifestyle factors, and a cervical sample was collected. HPV DNA detection was performed by GP5+/GP6+ primer-mediated PCR. HPV-positive samples were genotyped by multiplex PCR. A pilot analysis of HLA-G promoter methylation was carried out in a subset of the study population (96 cases and 76 controls) by pyrosequencing. HLA-G methylation and HPV infection status of cases and controls were compared, and confounding factors were computed by t Student and non-parametric Wilcoxon tests. Comparison of HLA-G methylation between cases and controls was assessed by the Bonferroni correction. The association of HLA-G methylation with CIN2/3 was evaluated by logistic regression. RESULTS: HPV prevalence was 19.6% in controls and 94.3% in CIN2/3 cases. HPV16, 31, 33, 35 and 18 were the most prevalent types. Methylation analysis of seven CpGs in the HLA-G promoter did not reveal any spontaneous de-methylation events in CIN2/3 cases (mean proportion of methylation: 75.8%) with respect to controls (mean 73.7%; odds ratio 1.01, 95% confidence interval 0.96, 1.07). CONCLUSIONS: This study did not support the hypothesis that spontaneous de-methylation events in the HLA-G promoter play a primary role in promoting escape from immunosurveillance in the development of precancerous cervical lesions

Genome-wide association study identifies a variant in HDAC9 associated with large vessel ischemic stroke

Genetic factors have been implicated in stroke risk but few replicated associations have been reported. We conducted a genome-wide association study (GWAS) in ischemic stroke and its subtypes in 3,548 cases and 5,972 controls, all of European ancestry. Replication of potential signals was performed in 5,859 cases and 6,281 controls. We replicated reported associations between variants close to PITX2 and ZFHX3 with cardioembolic stroke, and a 9p21 locus with large vessel stroke. We identified a novel association for a SNP within the histone deacetylase 9(HDAC9) gene on chromosome 7p21.1 which was associated with large vessel stroke including additional replication in a further 735 cases and 28583 controls (rs11984041, combined P = 1.87×10−11, OR=1.42 (95% CI) 1.28-1.57). All four loci exhibit evidence for heterogeneity of effect across the stroke subtypes, with some, and possibly all, affecting risk for only one subtype. This suggests differing genetic architectures for different stroke subtypes

Simultaneous CXCL12 and ESR1 CpG island hypermethylation correlates with poor prognosis in sporadic breast cancer

<p>Abstract</p> <p>Background</p> <p>CXCL12 is a chemokine that is constitutively expressed in many organs and tissues. <it>CXCL12 </it>promoter hypermethylation has been detected in primary breast tumours and contributes to their metastatic potential. It has been shown that the oestrogen receptor α (<it>ESR1</it>) gene can also be silenced by DNA methylation. In this study, we used methylation-specific PCR (MSP) to analyse the methylation status in two regions of the <it>CXCL12 </it>promoter and <it>ESR1 </it>in tumour cell lines and in primary breast tumour samples, and correlated our results with clinicopathological data.</p> <p>Methods</p> <p>First, we analysed <it>CXCL12 </it>expression in breast tumour cell lines by RT-PCR. We also used 5-aza-2'-deoxycytidine (5-aza-CdR) treatment and DNA bisulphite sequencing to study the promoter methylation for a specific region of <it>CXCL12 </it>in breast tumour cell lines. We evaluated <it>CXCL12 </it>and <it>ESR1 </it>methylation in primary tumour samples by methylation-specific PCR (MSP). Finally, promoter hypermethylation of these genes was analysed using Fisher's exact test and correlated with clinicopathological data using the Chi square test, Kaplan-Meier survival analysis and Cox regression analysis.</p> <p>Results</p> <p><it>CXCL12 </it>promoter hypermethylation in the first region (island 2) and second region (island 4) was correlated with lack of expression of the gene in tumour cell lines. In the primary tumours, island 2 was hypermethylated in 14.5% of the samples and island 4 was hypermethylated in 54% of the samples. The <it>ESR1 </it>promoter was hypermethylated in 41% of breast tumour samples. In addition, the levels of ERα protein expression diminished with increased frequency of <it>ESR1 </it>methylation (p < 0.0001). This study also demonstrated that <it>CXCL12 </it>island 4 and <it>ESR1 </it>methylation occur simultaneously at a high frequency (p = 0.0220).</p> <p>Conclusions</p> <p>This is the first study showing a simultaneous involvement of epigenetic regulation for both <it>CXCL12 </it>and <it>ESR1 </it>genes in Brazilian women. The methylation status of both genes was significantly correlated with histologically advanced disease, the presence of metastases and death. Therefore, the methylation pattern of these genes could be used as a molecular marker for the prediction of breast cancer outcome.</p

Cohort profile : demographic and clinical characteristics of the MILESTONE longitudinal cohort of young people approaching the upper age limit of their child mental health care service in Europe

Purpose: The presence of distinct child and adolescent mental health services (CAMHS) and adult mental health services (AMHS) impacts continuity of mental health treatment for young people. However, we do not know the extent of discontinuity of care in Europe nor the effects of discontinuity on the mental health of young people. Current research is limited, as the majority of existing studies are retrospective, based on small samples or used non-standardised information from medical records. The MILESTONE prospective cohort study aims to examine associations between service use, mental health and other outcomes over 24 months, using information from self, parent and clinician reports. Participants: Seven hundred sixty-three young people from 39 CAMHS in 8 European countries, their parents and CAMHS clinicians who completed interviews and online questionnaires and were followed up for 2 years after reaching the upper age limit of the CAMHS they receive treatment at. Findings to date: This cohort profile describes the baseline characteristics of the MILESTONE cohort. The mental health of young people reaching the upper age limit of their CAMHS varied greatly in type and severity: 32.8% of young people reported clinical levels of self-reported problems and 18.6% were rated to be ‘markedly ill’, ‘severely ill’ or ‘among the most extremely ill’ by their clinician. Fifty-seven per cent of young people reported psychotropic medication use in the previous half year. Future plans: Analysis of longitudinal data from the MILESTONE cohort will be used to assess relationships between the demographic and clinical characteristics of young people reaching the upper age limit of their CAMHS and the type of care the young person uses over the next 2 years, such as whether the young person transitions to AMHS. At 2 years follow-up, the mental health outcomes of young people following different care pathways will be compared. Trial registration number: NCT03013595

TEMAS POLÊMICOS E A ARGUMENTAÇÃO DE ESTUDANTES DO CURSO DE CIÊNCIAS BIOLÓGICAS

Analisa-se a estrutura e consistência dos argumentos de alunos do curso de Ciências Biológicas quando instigados a defender determinado ponto de vista sobre dois temas Mercado de Carbono e Experimetação Animal . Utilizando-se como referencial para análise o modelo de Toulmin, observou-se que prevaleceu Argumentos do tipo conclusão-justificativa e conclusão-dado-justificativa em ambos os debates, indicando que o método de argumentação dos alunos é derivado, principalmente, de opiniões próprias sobre o assunto ou de opiniões formadas através de aquisição de fatos aleatórios. De modo geral, os debates apresentaram uma boa expressividade e apesar dos argumentos não terem sido formuladas com base em dados científicos, há que se valorizar a importância desse tipo de atividade para o aprimoramento intelectual

TEMAS POLÊMICOS E A ARGUMENTAÇÃO DE ESTUDANTES DO CURSO DE CIÊNCIAS BIOLÓGICAS

Analisa-se a estrutura e consistência dos argumentos de alunos do curso de Ciências Biológicas quando instigados a defender determinado ponto de vista sobre dois temas "Mercado de Carbono" e "Experimetação Animal". Utilizando-se como referencial para análise o modelo de Toulmin, observou-se que prevaleceu Argumentos do tipo conclusão-justificativa e conclusão-dado-justificativa em ambos os debates, indicando que o método de argumentação dos alunos é derivado, principalmente, de opiniões próprias sobre o assunto ou de opiniões formadas através de aquisição de fatos aleatórios. De modo geral, os debates apresentaram uma boa expressividade e apesar dos argumentos não terem sido formuladas com base em dados científicos, há que se valorizar a importância desse tipo de atividade para o aprimoramento intelectual

Case–control study of HLA-G promoter methylation status, HPV infection and cervical neoplasia in Curitiba, Brazil: a pilot analysis

Abstract Background The causal association between persistent human papillomavirus (HPV) infection and cervical cancer has been established, but the mechanisms that favor HPV persistence in cervical cells are still unknown. The diminished capability of the immune system to control and resolve HPV infection is one of several hypotheses. The tolerogenic protein HLA-G has shown aberrant expression in a variety of cancers, which has been suggested as a mechanism for tumor escape from immunosurveillance. In the present study we evaluate the role of epigenetic modification (promoter de-methylation) of the HLA-G gene on susceptibility to HPV infection and development of high-grade cervical lesions. Methods A case–control study was carried out in Curitiba, Brazil, between February and June 2010. A total of 789 women aged 15–47 years were recruited: 510 controls with normal cervical cytology, and 279 cases with histologically confirmed cervical intraepithelial neoplasia grade 2 (CIN2, N = 150) or grade 3 (CIN3, N = 129). All women were administered a questionnaire by interview, which collected information on demographic and lifestyle factors, and a cervical sample was collected. HPV DNA detection was performed by GP5+/GP6+ primer-mediated PCR. HPV-positive samples were genotyped by multiplex PCR. A pilot analysis of HLA-G promoter methylation was carried out in a subset of the study population (96 cases and 76 controls) by pyrosequencing. HLA-G methylation and HPV infection status of cases and controls were compared, and confounding factors were computed by t Student and non-parametric Wilcoxon tests. Comparison of HLA-G methylation between cases and controls was assessed by the Bonferroni correction. The association of HLA-G methylation with CIN2/3 was evaluated by logistic regression. Results HPV prevalence was 19.6% in controls and 94.3% in CIN2/3 cases. HPV16, 31, 33, 35 and 18 were the most prevalent types. Methylation analysis of seven CpGs in the HLA-G promoter did not reveal any spontaneous de-methylation events in CIN2/3 cases (mean proportion of methylation: 75.8%) with respect to controls (mean 73.7%; odds ratio 1.01, 95% confidence interval 0.96, 1.07). Conclusions This study did not support the hypothesis that spontaneous de-methylation events in the HLA-G promoter play a primary role in promoting escape from immunosurveillance in the development of precancerous cervical lesions.</p