A genetic interaction between RAP1 and telomerase reveals an unanticipated role for RAP1 in telomere maintenance

RAP1 is one of the components of shelterin, the capping complex at chromosome ends or telomeres, although its role in telomere length maintenance and protection has remained elusive. RAP1 also binds subtelomeric repeats and along chromosome arms, where it regulates gene expression and has been shown to function in metabolism control. Telomerase is the enzyme that elongates telomeres, and its deficiency causes a premature aging in humans and mice. We describe an unanticipated genetic interaction between RAP1 and telomerase. While RAP1 deficiency alone does not impact on mouse survival, mice lacking both RAP1 and telomerase show a progressively decreased survival with increasing mouse generations compared to telomerase single mutants. Telomere shortening is more pronounced in Rap1-/- Terc-/- doubly deficient mice than in the single-mutant Terc-/- counterparts, leading to an earlier onset of telomere-induced DNA damage and degenerative pathologies. Telomerase deficiency abolishes obesity and liver steatohepatitis provoked by RAP1 deficiency. Using genomewide ChIP sequencing, we find that progressive telomere shortening owing to telomerase deficiency leads to re-localization of RAP1 from telomeres and subtelomeric regions to extratelomeric sites in a genomewide manner. These findings suggest that although in the presence of sufficient telomere reserve RAP1 is not a key factor for telomere maintenance and protection, it plays a crucial role in the context of telomerase deficiency, thus in agreement with its evolutionary conservation as a telomere component from yeast to humans.Research in the Blasco laboratory is funded by Spanish Ministry of Economy and Competitiveness (MINECO and FEDER) Project RETOS (SAF2013-45111-R), the European Research Council (ERC) Project TEL STEM CELL (ERC-2008-AdG/232854), and Fundacion Botin.S

Normal Proliferation and Tumorigenesis but Impaired Pancreatic Function in Mice Lacking the Cell Cycle Regulator Sei1

Sei1 is a positive regulator of proliferation that promotes the assembly of Cdk4-cyclin D complexes and enhances the transcriptional activity of E2f1. The potential oncogenic role of Sei1 is further suggested by its overexpression in various types of human cancers. To study the role of Sei1, we have generated a mouse line deficient for this gene. Sei1-null fibroblasts did not show abnormalities regarding proliferation or susceptibility to neoplastic transformation, nor did we observe defects on Cdk4 complexes or E2f activity. Sei1-null mice were viable, did not present overt pathologies, had a normal lifespan, and had a normal susceptibility to spontaneous and chemically-induced cancer. Pancreatic insulin-producing cells are known to be particularly sensitive to Cdk4-cyclin D and E2f activities, and we have observed that Sei1 is highly expressed in pancreatic islets compared to other tissues. Interestingly, Sei1-null mice present lower number of islets, decreased β-cell area, impaired insulin secretion, and glucose intolerance. These defects were associated to nuclear accumulation of the cell-cycle inhibitors p21Cip1 and p27Kip1 in islet cells. We conclude that Sei1 plays an important role in pancreatic β-cells, which supports a functional link between Sei1 and the core cell cycle regulators specifically in the context of the pancreas

Impact of telomerase ablation on organismal viability, aging, and tumorigenesis in mice lacking the DNA repair proteins PARP-1, Ku86, or DNA-PKcs

The DNA repair proteins poly(ADP-ribose) polymerase-1 (PARP-1), Ku86, and catalytic subunit of DNA-PK (DNA-PKcs) have been involved in telomere metabolism. To genetically dissect the impact of these activities on telomere function, as well as organismal cancer and aging, we have generated mice doubly deficient for both telomerase and any of the mentioned DNA repair proteins, PARP-1, Ku86, or DNA-PKcs. First, we show that abrogation of PARP-1 in the absence of telomerase does not affect the rate of telomere shortening, telomere capping, or organismal viability compared with single telomerase-deficient controls. Thus, PARP-1 does not have a major role in telomere metabolism, not even in the context of telomerase deficiency. In contrast, mice doubly deficient for telomerase and either Ku86 or DNA-PKcs manifest accelerated loss of organismal viability compared with single telomerase-deficient mice. Interestingly, this loss of organismal viability correlates with proliferative defects and age-related pathologies, but not with increased incidence of cancer. These results support the notion that absence of telomerase and short telomeres in combination with DNA repair deficiencies accelerate the aging process without impacting on tumorigenesis

Increased p53 gene dosage reduces neointimal thickening induced by mechanical injury but has no effect on native atherosclerosis

This is a pre-copy-editing, author-produced PDF of an article accepted for publication in Cardiovascular Research following peer review. The definitive publisher-authenticated version Cardiovasc Res. 75 (4):803-12. is available online at: http://cardiovascres.oxfordjournals.org/cgi/content/full/75/4/803OBJECTIVE: The tumor suppressor p53 regulates cell proliferation and apoptosis, two key processes in the pathogenesis of occlusive vascular disease. Here, we examined the consequences of heightening p53 function on neointimal lesion formation in the setting of atherosclerosis and mechanical injury. METHODS: (1) Immunohistopathological characterization of neointimal lesions in atherosclerosis-prone apolipoprotein E-null mice with normal p53 gene dosage (apoEKO) and carrying a p53 transgene (Super-p53/apoE-KO); (2) molecular studies in macrophages and smooth muscle cells (SMCs) obtained from these mice. RESULTS: The p53 transgene conferred p53 gain-of-function in cultured cells and mice. In vitro, survival of irradiated Super-p53 macrophages and femoral SMCs was reduced, but only Super-p53 SMCs exhibited attenuated proliferation. In vivo, whereas the size of spontaneously formed and diet-induced aortic atheromas was undistinguishable in apoE-KO and Super-p53/apoE-KO mice, the latter exhibited attenuated neointimal thickening in mechanically-injured femoral artery. In both models, neither apoptosis nor cell proliferation were affected by additional p53 gene dosage when examined in established neointimal lesions. However, at 2 days after mechanical injury when neointimal lesions were not formed yet, cell proliferation was significantly attenuated within medial SMCs of Super-p53/apoEKO mice. CONCLUSION: Heightening p53 function has differential effects on in vitro proliferation of macrophages (unaffected) versus SMCs (reduced), and on native atherosclerosis (unaffected) versus mechanically-induced neointimal thickening (reduced) in apoE-KO mice. The protective effect of p53 in mechanically-injured femoral artery coincided with limited medial SMC proliferation at early time points preceding neointima formation, but neither medial nor neointimal cell proliferation was affected in vessels with established occlusive lesions. These findings corroborate p53 gain-of-function as a promising therapeutic strategy to limit post-angioplasty restenosis but not native atherosclerosis.Work financed by grants from Ministerio de Sanidad y Consumo/Instituto de Salud Carlos III (Red Temática de Investigación Cooperativa en Enfermedades Cardiovasculares, RECAVA), from the Regional Government of Valencia (GV04B-288) and from Ministerio de Educación y Ciencia and the European Regional Development Fund (SAF2004-03057). S.M.S.-G. and J.M.G received salary support from Instituto de Salud Carlos III, and J.J.F. from CSIC-I3P predoctoral fellowship program cosponsored by the European Social Fund.Peer reviewe

Cannabinoids reduce ErbB2-driven breast cancer progression through Akt inhibition.

RIGHTS : This article is licensed under the BioMed Central licence at http://www.biomedcentral.com/about/license which is similar to the 'Creative Commons Attribution Licence'. In brief you may : copy, distribute, and display the work; make derivative works; or make commercial use of the work - under the following conditions: the original author must be given credit; for any reuse or distribution, it must be made clear to others what the license terms of this work are.BACKGROUND: ErbB2-positive breast cancer is characterized by highly aggressive phenotypes and reduced responsiveness to standard therapies. Although specific ErbB2-targeted therapies have been designed, only a small percentage of patients respond to these treatments and most of them eventually relapse. The existence of this population of particularly aggressive and non-responding or relapsing patients urges the search for novel therapies. The purpose of this study was to determine whether cannabinoids might constitute a new therapeutic tool for the treatment of ErbB2-positive breast tumors. We analyzed their antitumor potential in a well established and clinically relevant model of ErbB2-driven metastatic breast cancer: the MMTV-neu mouse. We also analyzed the expression of cannabinoid targets in a series of 87 human breast tumors. RESULTS: Our results show that both Delta9-tetrahydrocannabinol, the most abundant and potent cannabinoid in marijuana, and JWH-133, a non-psychotropic CB2 receptor-selective agonist, reduce tumor growth, tumor number, and the amount/severity of lung metastases in MMTV-neu mice. Histological analyses of the tumors revealed that cannabinoids inhibit cancer cell proliferation, induce cancer cell apoptosis, and impair tumor angiogenesis. Cannabinoid antitumoral action relies, at least partially, on the inhibition of the pro-tumorigenic Akt pathway. We also found that 91% of ErbB2-positive tumors express the non-psychotropic cannabinoid receptor CB2. CONCLUSIONS: Taken together, these results provide a strong preclinical evidence for the use of cannabinoid-based therapies for the management of ErbB2-positive breast cancer

OBESIDAD EN ADOLESCENTES ESCOLARIZADOS COMO FACTOR DE RIESGO EN DESARROLLO DE DIABETES EN CIUDAD JUÁREZ, CHIHUAHUA, MÉXICO

La obesidad en alumnos adolescentes es el resultado de cambios en los hábitos alimenticios en donde predomina la comida rápida y alimentos chatarra, y en el estilo de vida, falta de ejercicio o sedentarismo, y trae como consecuencia un incremento importante de diabetes tipo 2 en esta población en la Frontera de MéxicoEstados Unidos. Se estudió a 415 alumnos de 3 escuelas secundarias; se contó con la autorización firmada de los padres y autoridades escolares, se respetó el anonimato y la participación voluntaria y se derivó a tratamiento médico a población detectada con riesgo. Se determinó glucosa según DIABETIMSS, ÍMC, entre otras, el análisis se hizo con SPSS 17.0. Resultados; edad ± 14 años, AFD diabetes 64 %, acantosis nigricans 7.47 %, consumo alimentos chatarra 26.5 %, sobrepeso-obesidad 35.4 %, riesgo para desarrollo de DM; mujer (OR 3.8, IC 1.85-7.77). Discusión; La población adolescente escolarizada presenta de forma alarmante problemas con sobre peso y obesidad lo que implica un riesgo para el desarrollo de diabetes mellitus tipo 2, la prevalencia encontrada fue de 9.6%, por lo que a temprana edad es fundamental promover la educación en salud sobre estilos de vida saludables. Abstarct Obesity in adolescent students is the result of changes in eating habits in a predominantly fast food and junk food, and lack of exercise or sedentary lifestyle, and results in a significant increase in type 2 diabetes in this population at the Border Mexico-United States. We studied 415 students in three high schools, we had the authorization signed by parents and school authorities respected the anonymity and voluntary participation and led to medical treatment for people at risk detected. Glucose was determined according DIABETIMSS, BMI, among others; the analysis was done with SPSS 17.0. Results: age ± 14 years, family history of diabetes 64%, 7.47% acanthosis nigricans, junk food consumption 26.5%, 35.4% overweight, obesity, risk for development of DM; women (OR 3.8, CI 1.85-7.77). Discussion, The adolescent population presents an alarming overweight and obesity which is a risk for developing type 2 diabetes mellitus, the prevalence was 9.6%, so it is essential to promote health education on healthy lifestyles early. Palabras Clave: Obesidad, Adolescente, Diabetes.

Distinct p21 requirements for regulating normal and self-reactive T cells through IFN-γ production.

Self/non-self discrimination characterizes immunity and allows responses against pathogens but not self-antigens. Understanding the principles that govern this process is essential for designing autoimmunity treatments. p21 is thought to attenuate autoreactivity by limiting T cell expansion. Here, we provide direct evidence for a p21 role in controlling autoimmune T cell autoreactivity without affecting normal T cellresponses. We studied C57BL/6, C57BL/6/lpr and MRL/lpr mice overexpressing p21 in T cells, and showed reduced autoreactivity and lymphadenopathy in C57BL/6/lpr, and reduced mortality in MRL/lpr mice. p21 inhibited effector/memory CD4(+) CD8(+) and CD4(-)CD8(-) lpr T cell accumulation without altering defective lpr apoptosis. This was mediated by a previously non-described p21 function in limiting T cell overactivation and overproduction of IFN-γ, a key lupus cytokine. p21 did not affect normal T cell responses, revealing differential p21 requirements for autoreactive and normal T cell activity regulation. The underlying concept of these findings suggests potential treatments for lupus and autoimmune lymphoproliferative syndrome, without compromising normal immunity.This work was supported by grants from the Ministry of Economy and Competitivity (MINECO)/Instituto Carlos III (PI081835 PI11/00950) and the CAM (MITIC S2011/ BMD2502) to DB, and from the MINECO (SAF2010-21205 and PIB2010BZ-00564) and the CAM (MITIC S2011/BMD2502) to CMA.Peer reviewe

Recolección de hongos comestibles silvestres en el contexto del pastoreo de alta montaña en la localidad de Agua Blanca en el Nevado de Toluca, México

Objective: Describe the collection of wild edible mushrooms that occurs in the rainy season in Agua Blanca, located in the Area of Protection of Flora and Fauna Nevado de Toluca Design, methodology and approximation: Simple case study with qualitative perspective and ethnomethodological approach. Results: They were detected 57 species of wild edible mushrooms that are collected in the context of high mountain grazing, being the production and management of sheep the main productive and economic activity in which they spend their time, alternating this activity with the mushrooms harvesting in rainy season. Limitations and implications: It is a descriptive and exploratory work that only allows contributing to the documentation of the phenomenon within the study area. Findings and conclusions: Mushroom harvesting is a complementary activity to livestock grazing and an opportunity to obtain extra income that allows families to survive during this season.Objetivo: Describir la recolección de hongos comestibles silvestres que se da en temporada de lluvias en la localidad Agua Blanca, ubicada en el Área de Protección de Flora y Fauna Nevado de Toluca Diseño, metodología y aproximación: Estudio de caso simple con perspectiva cualitativa y aproximación etnometodológica. Resultados: Fueron detectadas 57 especies de hongos comestibles silvestres que se recolectan en el contexto de pastoreo de alta montaña, siendo la producción y manejo de ganado ovino la principal actividad productiva y económica en la que emplean su tiempo, alternando esta actividad con la recolección de hongos en temporada de lluvias. Limitaciones e implicaciones: Se trata de un trabajo descriptivo y exploratorio que sólo permite contribuir a la documentación del fenómeno dentro del área de estudio. Hallazgos y conclusiones: La recolección de hongos es una actividad complementaria al pastoreo del ganado y una oportunidad de obtener ingresos extras que permiten la subsistencia de las familias durante esta temporada