Transcriptional activation of the Lats1 tumor suppressor gene in tumors of CUX1 transgenic mice

<p>Abstract</p> <p>Background</p> <p><it>Lats1 </it>(large tumor suppressor 1) codes for a serine/threonine kinase that plays a role in the progression through mitosis. Genetic studies demonstrated that the loss of LATS1 in mouse, and of its ortholog <it>wts </it>(warts) in Drosophila, is associated with increased cancer incidence. There are conflicting reports, however, as to whether overexpression of <it>Lats1 </it>inhibits cell proliferation. CUX1 is a transcription factor that exists in different isoforms as a result of proteolytic processing or alternative transcription initiation. Expression of p110 and p75 CUX1 in transgenic mice increases the susceptibility to cancer in various organs and tissues. In tissue culture, p110 CUX1 was shown to accelerate entry into S phase and stimulate cell proliferation.</p> <p>Results</p> <p>Genome-wide location arrays in cell lines of various cell types revealed that <it>Lats1 </it>was a transcriptional target of CUX1. Scanning ChIP analysis confirmed that CUX1 binds to the immediate promoter of <it>Lats1</it>. Expression of <it>Lats1 </it>was reduced in cux1^-/-MEFs, whereas it was increased in cells stably or transiently expressing p110 or p75 CUX1. Reporter assays confirmed that the immediate promoter of <it>Lats1 </it>was sufficient to confer transcriptional activation by CUX1. <it>Lats1 </it>was found to be overexpressed in tumors from the mammary gland, uterus and spleen that arise in p110 or p75 CUX1 transgenic mice. In tissue culture, such elevated LATS1 expression did not hinder cell cycle progression in cells overexpressing p110 CUX1.</p> <p>Conclusion</p> <p>While inactivation of <it>Lats1</it>/<it>wts </it>in mouse and Drosophila can increase cancer incidence, results from the present study demonstrate that <it>Lats1 </it>is a transcriptional target of CUX1 that can be overexpressed in tumors of various tissue-types. Interestingly, two other studies documented the overexpression of <it>LATS1 </it>in human cervical cancers and basal-like breast cancers. We conclude that, similarly to other genes involved in mitotic checkpoint, cancer can be associated with either loss-of-function or overexpression of <it>Lats1</it>.</p

Genome-wide location analysis and expression studies reveal a role for p110 CUX1 in the activation of DNA replication genes

Proteolytic processing of the CUX1 transcription factor generates an isoform, p110 that accelerates entry into S phase. To identify targets of p110 CUX1 that are involved in cell cycle progression, we performed genome-wide location analysis using a promoter microarray. Since there are no antibodies that specifically recognize p110, but not the full-length protein, we expressed physiological levels of a p110 isoform with two tags and purified chromatin by tandem affinity purification (ChAP). Conventional ChIP performed on synchronized populations of cells confirmed that p110 CUX1 is recruited to the promoter of cell cycle-related targets preferentially during S phase. Multiple approaches including silencing RNA (siRNA), transient infection with retroviral vectors, constitutive expression and reporter assays demonstrated that most cell cycle targets are activated whereas a few are repressed or not affected by p110 CUX1. Functional classes that were over-represented among targets included DNA replication initiation. Consistent with this finding, constitutive expression of p110 CUX1 led to a premature and more robust induction of replication genes during cell cycle progression, and stimulated the long-term replication of a plasmid bearing the oriP replicator of Epstein Barr virus (EBV).The pc3oriPE plasmid and helpful advices were kindly provided by Dr Lori Frappier. A.N. is the recipient of a scholarship from the Fonds de la Recherche en Sante´ du Québec. C.V. is the recipient of a studentship from the McGill University Cancer Consortium Training Grant in Cancer Research (sponsored by CIHR). F.R. holds a new investigator award from the CIHR. This research was supported by grant No. 014288 from the Canadian Cancer Society to A.N. and a grant from Genome Canada/ Génome Québec to F.R and A.N. Funding to pay the Open Access publication charges for this article was provided by grant No. 014288 from the Canadian Cancer Society to A.N

A Cathepsin L Isoform that Is Devoid of a Signal Peptide Localizes to the Nucleus in S Phase and Processes the CDP/Cux Transcription Factor

AbstractThe subclass of cysteine proteases termed lysosomal cathepsins has long been thought to be primarily involved in end-stage protein breakdown within lysosomal compartments. Furthermore, few specific protein substrates for these proteases have been identified. We show here that cathepsin L functions in the regulation of cell cycle progression through proteolytic processing of the CDP/Cux transcription factor. CDP/Cux processing in situ was increased following ectopic expression of cathepsin L but was reduced in Cat L−/− cells. Furthermore, catalytically active cathepsin L was localized to the nucleus during the G1-S transition as detected by immunofluorescence imaging and labeling using activity-based probes. Trafficking of cathepsin L to the nucleus is accomplished through a mechanism involving translation initiation at downstream AUG sites and the synthesis of proteases that are devoid of a signal peptide. Overall, these results uncover an as yet unsuspected role for cysteine proteases in the control of cell cycle progression

Phenotypic and genotypic correlations for wood properties of hybrid poplar clones of southern Quebec

: This study aims to understand the phenotypic and genotypic correlations among wood anatomical, physical, and mechanical properties of hybrid poplar clones. Samples were taken from seven clones grown on three sites in Southern Quebec, Canada. Five trees per clone were randomly sampled from each site to measure anatomical (fiber length, fiber proportion, vessel proportion, fiber wall thickness, tension wood), physical (basic density, volumetric, longitudinal, tangential, and radial shrinkage), and mechanical wood properties (flexural modulus of elasticity (MOE), modulus of rupture (MOR), ultimate crushing strength parallel to the grain). The observed phenotypic and genotypic correlations between these wood properties were moderate to strong, except for fiber length and vessel proportion. Genotypic correlations for all wood properties were higher than for corresponding phenotypic correlations. Furthermore, fiber length showed weak correlations, whereas, vessel proportion showed strongly negative correlations with all other properties. Strong correlations were also found among fiber proportion, fiber wall thickness, basic density, and mechanical properties. Furthermore, results from this study show close genotypic and phenotypic correlations between fiber proportion, fiber wall thickness, and wood density, which consequently affect the mechanical performance of wood products. These findings indicate that there is a substantial opportunity to improve wood quality by selecting several wood properties for different end uses

CUX1 transcription factor is required for optimal ATM/ATR-mediated responses to DNA damage

The p110 Cut homeobox 1 (CUX1) transcription factor regulates genes involved in DNA replication and chromosome segregation. Using a genome-wide-approach, we now demonstrate that CUX1 also modulates the constitutive expression of DNA damage response genes, including ones encoding ATM and ATR, as well as proteins involved in DNA damage-induced activation of, and signaling through, these kinases. Consistently, RNAi knockdown or genetic inactivation of CUX1 reduced ATM/ATR expression and negatively impacted hallmark protective responses mediated by ATM and ATR following exposure to ionizing radiation (IR) and UV, respectively. Specifically, abrogation of CUX1 strongly reduced ATM autophosphorylation after IR, in turn causing substantial decreases in (i) levels of phospho-Chk2 and p53, (ii) γ-H2AX and Rad51 DNA damage foci and (iii) the efficiency of DNA strand break repair. Similarly remarkable reductions in ATR-dependent responses, including phosphorylation of Chk1 and H2AX, were observed post-UV. Finally, multiple cell cycle checkpoints and clonogenic survival were compromised in CUX1 knockdown cells. Our results indicate that CUX1 regulates a transcriptional program that is necessary to mount an efficient response to mutagenic insult. Thus, CUX1 ensures not only the proper duplication and segregation of the genetic material, but also the preservation of its integrity

Inhibition of Notch pathway arrests PTEN-deficient advanced prostate cancer by triggering p27-driven cellular senescence

Activation of NOTCH signalling is associated with advanced prostate cancer and treatment resistance in prostate cancer patients. However, the mechanism that drives NOTCH activation in prostate cancer remains still elusive. Moreover, preclinical evidence of the therapeutic efficacy of NOTCH inhibitors in prostate cancer is lacking. Here, we provide evidence that PTEN loss in prostate tumours upregulates the expression of ADAM17, thereby activating NOTCH signalling. Using prostate conditional inactivation of both Pten and Notch1 along with preclinical trials carried out in Pten-null prostate conditional mouse models, we demonstrate that Pten-deficient prostate tumours are addicted to the NOTCH signalling. Importantly, we find that pharmacological inhibition of γ-secretase promotes growth arrest in both Pten-null and Pten/Trp53-null prostate tumours by triggering cellular senescence. Altogether, our findings describe a novel pro-tumorigenic network that links PTEN loss to ADAM17 and NOTCH signalling, thus providing the rational for the use of γ-secretase inhibitors in advanced prostate cancer patients

Romantismo e objetividade: notas sobre um panorama do Rio de Janeiro

The article deals with the great Panorama of Rio de Janeiro exhibited in Paris, 1824, and its sources - a series of watercolours which have also generated succeeding engravings produced dur-ing the 1830s. Panoramas, in their early formal conventions are shown to interplay with Romanticism's and Naturphilosophie's theses and to put in motion the legacy of 11th-century paint-ing . As this geme of visual device develops, Rio's watercoulours display symptoms of a gradual dismissal of its initial ambilions, through lhe treatment of the natural site and the city. At last the invention of the daguerreotype and vai d'oiseau urban images, among other traits, signale the changes in sensibility related to the production and consumption of those circular canvasses. From 1840/50 on panoramas conceived by the will to fuse art and science and bya reflection on nature and liberty turn essentially into a mass entertainment.Romantismo e objetividade: notas sobre um panorama do Rio de Janeiro Margarelh da Silva Pereira Enfoca O grande Panorama do Rio de Janeiro, exibido em Paris em 1824, do qual se conhece a série de aquarelas que serviram de base tanto àquela ampliação quanto às sucessivas gravuras da cena que foram produzidas na década de 1830. Busca-se mostrar como os panoramas em sua formalização inicial dialogam com as teses do romantismo e da Naturphilosophie, mobilizan-do heranças da pintura seiscentista. No desenvolvimento desta forma de exibição as aquarelas do Rio apresentam sintomas do gradual afastamento das ambições iniciais através do tratamento dispensado ao sítio natural e à cidade. Por fim, a invenção do daguerreótipo, e as vistas urbanas em võo de pássaro, enlre outros, balizariam a mudança de sensibilidade na produção e na fruição dessas telas circulares. A partir de 1840/50 os panoramas engendrados pelo desejo de fusão entre arte e ciência e pela reflexão sobre a natureza e a liberdade, tornar-se-iam, sobretudo, um divertimento de massas

L'intégration d'une molécule d'ADN, contenant des séquences hautement répétitives, dans le génome de cellules de rat

Nous avons voulu vérifier s'il était possible, dans les cellules somatiques, de diriger l'intégration d'une molécule de DNA au niveau d'un site cellulaire homologue. Nous avons transféré, dans des cellules de rat, une molécule d'ADN recombinant (Rml), contenant un génome complet du virus du polyome associé à des séquences cellulaires hautement répétitives et polydispersées. Nous avons isolé des foyers de cellules transformées et nous avons fait l'analyse des insertions de Rml présentes dans les génomes de ces cellules. Dans le clone 11.6, un des crossing-over ayant conduit à l'intégration de Rml, a fait intervenir une région de cette molécule contenant des séquences répétitives. L'analyse de ce crossing-over allait nous permettre de vérifier si l'homologie peut jouer un rôle dans les mécanismes de recombinaison intervenant lors de l'intégration d'ADN exogène dans le génome de cellules animales. Nous avons cloné une partie du site d'intégration du clone 11.6, comprenant la jonction ""séquence cellulaire de rat-région répétitive de Rml"". Nous avons utilisé une séquence unique flanquant cette jonction pour cloner le site original dans lequel s'était intégré Rml. Nous avons séquencé les régions appropriées de ces divers fragments d'ADN. Nos résultats montrent que la molécule Rml s'était intégrée par recombinaison illégitime en dépit de la présence de séquences homologues à proximité du site d'intégration. Nous concluons qu'il n'est pas possible, dans les cellules animales, de faire de l'intégration dirigée en absence de sélection

L'intégration d'une molécule d'ADN, contenant des séquences hautement répétitives, dans le génome de cellules de rat

Nous avons voulu vérifier s'il était possible, dans les cellules somatiques, de diriger l'intégration d'une molécule de DNA au niveau d'un site cellulaire homologue. Nous avons transféré, dans des cellules de rat, une molécule d'ADN recombinant (Rml), contenant un génome complet du virus du polyome associé à des séquences cellulaires hautement répétitives et polydispersées. Nous avons isolé des foyers de cellules transformées et nous avons fait l'analyse des insertions de Rml présentes dans les génomes de ces cellules. Dans le clone 11.6, un des crossing-over ayant conduit à l'intégration de Rml, a fait intervenir une région de cette molécule contenant des séquences répétitives. L'analyse de ce crossing-over allait nous permettre de vérifier si l'homologie peut jouer un rôle dans les mécanismes de recombinaison intervenant lors de l'intégration d'ADN exogène dans le génome de cellules animales. Nous avons cloné une partie du site d'intégration du clone 11.6, comprenant la jonction ""séquence cellulaire de rat-région répétitive de Rml"". Nous avons utilisé une séquence unique flanquant cette jonction pour cloner le site original dans lequel s'était intégré Rml. Nous avons séquencé les régions appropriées de ces divers fragments d'ADN. Nos résultats montrent que la molécule Rml s'était intégrée par recombinaison illégitime en dépit de la présence de séquences homologues à proximité du site d'intégration. Nous concluons qu'il n'est pas possible, dans les cellules animales, de faire de l'intégration dirigée en absence de sélection

Apurinic/apyrimidinic endonuclease 1 performs multiple roles in controlling the outcome of cancer cells toward radiation and chemotherapeutic agents

Many endogenous and exogenous sources produce reactive oxygen species such as superoxide radical anions and hydrogen peroxide that are converted to the highly reactive form, hydroxyl radical. It is this latter species that can damage several macromolecules in the cells, in particular, the DNA to produce a variety of DNA lesions. These DNA lesions include oxidatively damaged purine and pyrimidine bases, as well as single-strand and double-strand breaks. These unrepaired DNA lesions lead to base substitutions, deletions, insertions, and rearrangements of the chromosome, ultimately altering the stability of the genome. Maintaining the integrity of the genome is essential to prevent various diseases such as several types of cancers. There are several DNA repair pathways including base-excision repair (BER), nucleotide-excision repair, mismatch repair, homologous recombination, and nonhomologous end joining that operate in the human cells to prevent genomic instability. Each of these DNA repair pathways consists of multiple enzymes that execute specific function (s). This review focuses on a key enzyme apurinic/apyrimidinic endonuclease 1 (APE1) that belongs to the BER pathway that plays a pivotal role in the removal of modified DNA bases. We provide an overview of the multifaceted roles performed by APE1, which also serves as a redox factor and referred to as redox effector factor 1 (Ref-1) or APE1/Ref-1. In addition, we discuss more recent findings whereby (i) peroxiredoxin 1 controls the redox activity of APE1 and (ii) CUT-like homeobox 1 protein, a transcription factor that binds to DNA and stimulates the DNA repair activities of APE1 to confer resistance to radio- and chemotherapy