New ligands of the Cellular Retinoic Acid-Binding Protein 2 (CRABP2) suggest a role for this protein in chromatin remodeling

Retinoic acid (RA) regulates the transcription of a series of genes involved in cell proliferation, differentiation and apoptosis by binding to the RA Receptor (RAR) and Retinoid X Receptor (RXR) heterodimers. The cellular retinoic acid-binding protein 2 (CRABP2) is involved in the transport of RA from the cytosol to specific RA receptors in the nucleus, acting as a coactivator of nuclear retinoid receptors. In order to have a better understanding of the role of CRABP2 in RA signaling, we used the yeast two-hybrid system as a tool for the identification of physical protein-protein interactions. Twenty-three putative CRABP2-interacting proteins were identified by screening in the presence of RA, five of which are related to transcription regulation or, more specifically, to the process of chromatin remodeling: t-complex 1 (TCP1); H3 histone, family 3A (H3F3A); H3 histone, family 3B (H3F3B); β-tubulin (TUBB) and SR-related CTD-associated factor 1 (SCAF1). These results suggest a more direct role for CRABP2 in chromatin remodeling and may be a starting point for the elucidation of the fine-tuning control of transcription by RA receptors...

Caracterização funcional da interação entre as proteínas CTSP-1 e CTCF / Functional characterization of the interaction between the proteins CTSP-1 and CTCF

Os antígenos cancer-testis (CT) são proteínas imunogênicas expressas em tecido gametogênico e em diferentes tipos de tumor, sendo considerados candidatos promissores para a imunoterapia do câncer. Entretanto, pouco se sabe sobre a função desses antígenos na tumorigênese. Em 2006, identificamos CTSP-1 como um novo antígeno CT, frequentemente expresso em vários tumores. Nesse trabalho, investigamos a função de CTSP-1 por meio da identificação de proteínas expressas em tumores de próstata e que são capazes de interagir fisicamente com esse antígeno. Demonstramos que CTSP-1 interage com a proteína CTCF em ensaios de duplo-híbrido em leveduras, pulldown e de co-localização e, em seguida, analisamos o impacto da superexpressão de CTSP-1 no controle da expressão de genes CT mediada por CTCF e na progressão do ciclo celular. Utilizando o CT NY-ESO-1 como modelo, demonstramos que a superexpressão de CTSP-1 não altera os níveis endógenos de NY-ESO-1 na linhagem celular tumoral H1299. Por outro lado, observamos que a superexpressão de CTSP-1 48h após as transfecções em H1299 induz um bloqueio do ciclo em G0/G1, reduzindo a capacidade clonogênica dessas células por um mecanismo dependente dos níveis de expressão de CTSP-1. Resultados semelhantes não foram observados em ensaios com clones superexpressando CTSP-1 estavelmente, o que sugere que eles tenham se originado de células que conseguiram escapar do bloqueio em G0/G1. Resultados preliminares sugerem que a redução da capacidade clonogênica das células H1299 que superexpressam CTSP-1 48h após as tansfecções não está associada à ocorrência de morte por apoptose

Cancer-testis (CT) antigens are immunogenic proteins expressed in gametogenic tissues and in different histological types of tumors, being considered promising candidates for cancer immunotherapy. However, little is known about their role in tumorigenesis. In 2006, we identified CTSP-1 as a novel CT antigen, frequently expressed in different types of tumors. In this work, we investigated the functional role of CTSP-1 through the identification of proteins expressed in prostate tumors and that physically interact with this tumor antigen. We demonstrate that CTSP-1 interacts with the CTCF protein using the yeast two-hybrid system, pulldown and co-localization assays and have further analyzed the impact of CTSP-1 overexpression on the expression of CT genes mediated by CTCF and on the cell cycle progression. Using the CT antigen NY-ESO-1 as a model, we showed that the CTSP-1 overexpression does not alter the endogenous levels of NY-ESO-1 in the tumor cell line H1299. On the other hand, we observed that the overexpression of CTSP-1 in H1299 cells 48h after the transfections induces a cell cycle arrest in G0/G1 and reduces the clonogenic capacity of these cells by a mechanism dependent on the CTSP-1 expression levels. Similar results were not observed for cell clones stably overexpressing CTSP-1, suggesting that these clones have arisen from cells that managed to escape cell cycle arrest in G0/G1. Preliminary results suggest that the reduced clonogenic capacity of H1299 cells expressing CTSP-1 and analyzed 48h after the transfections is not associated with cell death by apoptosis

Prevalence and risk factors of human papillomavirus infection in asymptomatic women in a Venezuelan urban area

The purpose of this study was to investigate the prevalence and risk factors of genital human papillomavirus (HPV) infection in asymptomatic women, using the HPV DNA Hybrid Capture 2 (HC2) test. Three hundred and two women who attended the Out-Patient Gynecological Clinic of a tertiary level hospital, in a Venezuelan urban area, were selected for the study. A pap smear, a cervical swab for HC2 and gynecological exam were performed to each patient. The HC2 testing showed that 47 samples (15.6%) were positive to HPV. Forty patients (13.2%) were positive to high risk-HPV (HR-HPV) and 11 (3.6%) were positive to low-risk-HPV (LR-HPV). The prevalence of HPV infections was higher for women under 35 years (51.1%; p < 0.02), and decreased to 6.4% for women 65 years old. Women who had not finished high school had a higher prevalence of HPV infection (p < 0.035). Twenty six (42.6%) of 61 pathological Pap smears were positives to HPV infection. A statistically significant difference was found when HPV infection was compared in normal and abnormal Pap smear (HSIL+LSIL; p<0.0001). Twenty four of 56 (43%) women with diagnosis of LSIL, and 2(40%) of 5 with diagnosis of HSIL were positive for HPV infection. A statistically significant difference was found when we compared HPV infection in negative Pap smears and those with LSIL (p<0.001). The present study found that the prevalence of HPV infection in asymptomatic Venezuelan women who attended a tertiary level hospital was 15.6%. HPV infection was more frequent in young adult, and in women with low educational level.

El propósito de este estudio fue investigar la prevalencia y factores de riesgo que influencia la presencia de la infección por el virus del papiloma humano (VPH) en pacientes asintomáticas que asistieron a un hospital nivel 3 en un área urbana venezolana. Se estudiaron las pacientes que acudieron a la Consulta de Patología del Cuello Uterino del Hospital Manuel Noriega Trigo. A cada paciente se le realizó una historia clínica, toma de citología cervico-vaginal y una muestra del cérvix para captura de híbridos 2(CH2). Se incluyeron 302 pacientes. La CH2 mostró 47 muestras (15,6%) positivas al VPH. Cuarenta mujeres (13,2%) fueron positivas a VPH de alto riesgo (VPH-AR) y 11 (3,6%) a VPH de bajo riesgo (VPH-BR). La prevalencia de la infección por VPH fue más alta en mujeres 35 años (51,1%; p < 0,02) y disminuyó a un 6,4% en mujeres 65 años. Las pacientes que no habían terminado los estudios de bachillerato presentaron un prevalencia más elevada del VPH (p < 0,035). Veinte y seis (42,6%) de 61 CCV patológicas fueron positivas a la infección del VPH. Una diferencia estadísticamente significativa fue encontrada cuando se comparó la presencia del VPH en las CCV normales con las CCV anormales (Lesión Intraepitelial Escamosa de Alto y Bajo Grado-LIE-AG y LIE-BG; p < 0,0001). Veinte y cuatro de 56 (43%) mujeres con diagnostico de LIE-BG, y 2(40%) de 5 con diagnóstico de LIE-AG fueron positivos a la presencia del VPH. Se encontró una diferencia estadísticamente significativa cuando se comparó la presencia de infección por el VPH en CCV normales y CCV con LIE-BG (p < 0,001). El presente estudio encontró una prevalencia de la infección por el VPH en mujeres asintomáticas que asisten a un hospital nivel 3 de 15,6% en área urbana venezolana. Fue más frecuente en mujeres jóvenes y de bajo nivel educacional.