Canonical wnt signaling activity in early stages of chick lung development

Wnt signaling pathway is an essential player during vertebrate embryonic development which has been associated with several developmental processes such as gastrulation, body axis formation and morphogenesis of numerous organs, namely the lung. Wnt proteins act through specific transmembrane receptors, which activate intracellular pathways that regulate cellular processes such as cell proliferation, differentiation and death. Morphogenesis of the fetal lung depends on epithelial-mesenchymal interactions that are governed by several growth and transcription factors that regulate cell proliferation, fate, migration and differentiation. This process is controlled by different signaling pathways such as FGF, Shh and Wnt among others. Wnt signaling is recognized as a key molecular player in mammalian pulmonary development but little is known about its function in avian lung development. The present work characterizes, for the first time, the expression pattern of several Wnt signaling members, such as wnt-1, wnt-2b, wnt-3a, wnt-5a, wnt-7b, wnt-8b, wnt-9a, lrp5, lrp6, sfrp1, dkk1, β-catenin and axin2 at early stages of chick lung development. In general, their expression is similar to their mammalian counterparts. By assessing protein expression levels of active/total β-catenin and phospho-LRP6/LRP6 it is revealed that canonical Wnt signaling is active in this embryonic tissue. In vitro inhibition studies were performed in order to evaluate the function of Wnt signaling pathway in lung branching. Lung explants treated with canonical Wnt signaling inhibitors (FH535 and PK115-584) presented an impairment of secondary branch formation after 48 h of culture along with a decrease in axin2 expression levels. Branching analysis confirmed this inhibition. Wnt-FGF crosstalk assessment revealed that this interaction is preserved in the chick lung. This study demonstrates that Wnt signaling is crucial for precise chick lung branching and further supports the avian lung as a good model for branching studies since it recapitulates early mammalian pulmonary development.Rute S. Moura was supported by a grant of ON.2 SR&TD Integrated Program (N-01-01-0124-01-07), ref: UMINHO/BPD/31/2013. The funders had no role in study design, data collection and analysis

β-catenin promotes endothelial survival by regulating eNOS activity and flow-dependent anti-apoptotic gene expression

Increased endothelial cell apoptosis is associated with the development of atherosclerotic plaques that develop predominantly at sites exposed to disturbed flow. Strategies to promote endothelial cell survival may therefore represent a novel therapeutic approach in cardiovascular disease. Nitric oxide (NO) and β-catenin have both been shown to promote cell survival and they interact in endothelial cells as we previously demonstrated. Here we investigated the physiological role of β-catenin as a mediator of NO-induced cell survival in endothelial cells. We found that β-catenin depleted human umbilical vein endothelial cells (HUVEC) stimulated with pharmacological activators of endothelial NO synthase (eNOS) showed a reduction in eNOS phosphorylation (Ser1177) as well as reduced intracellular cyclic guanosine monophosphate (cGMP) levels compared to control cells in static cultures. In addition, β-catenin depletion abrogated the protective effects of the NO donor, SNAP, during TNFα- and H2O2-induced apoptosis. Using an orbital shaker to generate shear stress, we confirmed eNOS and β-catenin interaction in HUVEC exposed to undisturbed flow (UF) and disturbed flow (DF) and showed that β-catenin depletion reduced eNOS phosphorylation. β- catenin depletion promoted apoptosis exclusively in HUVEC exposed to DF as did inhibition of soluble guanylate cyclase (sGC) or β-catenin transcriptional activity. The expression of the pro-survival genes, Bcl-2 and survivin was also reduced following inhibition of β-catenin transcriptional activity, as was the expression of eNOS. In conclusion, our data demonstrate that β-catenin is a positive regulator of eNOS activity and cell survival in human endothelial cells. sGC activity and β-catenin-dependent transcription of Bcl-2, survivin, BIRC3 and eNOS are essential to maintain cell survival in endothelial cells under DF

Pre-replication complex proteins assemble at regions of low nucleosome occupancy within the Chinese hamster dihydrofolate reductase initiation zone

Genome-scale mapping of pre-replication complex proteins has not been reported in mammalian cells. Poor enrichment of these proteins at specific sites may be due to dispersed binding, poor epitope availability or cell cycle stage-specific binding. Here, we have mapped sites of biotin-tagged ORC and MCM protein binding in G1-synchronized populations of Chinese hamster cells harboring amplified copies of the dihydrofolate reductase (DHFR) locus, using avidin-affinity purification of biotinylated chromatin followed by high-density microarray analysis across the DHFR locus. We have identified several sites of significant enrichment for both complexes distributed throughout the previously identified initiation zone. Analysis of the frequency of initiations across stretched DNA fibers from the DHFR locus confirmed a broad zone of de-localized initiation activity surrounding the sites of ORC and MCM enrichment. Mapping positions of mononucleosomal DNA empirically and computing nucleosome-positioning information in silico revealed that ORC and MCM map to regions of low measured and predicted nucleosome occupancy. Our results demonstrate that specific sites of ORC and MCM enrichment can be detected within a mammalian intitiation zone, and suggest that initiation zones may be regions of generally low nucleosome occupancy where flexible nucleosome positioning permits flexible pre-RC assembly sites

The F-box protein FBXO45 promotes the proteasome-dependent degradation of p73

The transcription factor p73, a member of the p53 family, mediates cell-cycle arrest and apoptosis in response to DNA damage-induced cellular stress, acting thus as a proapoptotic gene. Similar to p53, p73 activity is regulated by post-translational modification, including phosphorylation, acetylation and ubiquitylation. In C. elegans, the F-box protein FSN-1 controls germline apoptosis by regulating CEP-1, the single ancestral p53 family member. Here we report that FBXO45, the human ortholog of FSN-1, binds specifically to p73 triggering its proteasome-dependent degradation. Importantly, SCF(FBXO45) ubiquitylates p73 both in vivo and in vitro. Moreover, siRNA-mediated depletion of FBXO45 stabilizes p73 and concomitantly induces cell death in a p53-independent manner. All together, these results show that the orphan F-box protein FBXO45 regulates the stability of p73, highlighting a conserved pathway evolved from nematode to human by which the p53 members are regulated by an SCF-dependent mechanism

Design, Development and Testing an Academic Repository

Technological advances, established best web development practices, and modern design of the 21st century have provided students, professors, researchers, etc., quasi-effortless access to academic documents encompassed within cleaner user interface and a higher level of usability. Access to and rigorous management of research publication and products is also mandated by funding agencies. Given these characteristics, we have developed an academic repository to maintain the student projects in a typical academic department. A repository of this nature is comprised of two major components: the database and the user interface. The key focus is to provide secure access to research materials (e.g. Master\u27s projects and the like), similar to that of a community or university library\u27s online catalogs, while sustaining a keen eye for contemporary front-end design. In addition to providing access to documentation, this repository uses collected data to present various citation styles, assisting users with easy composition of reference pages. Through a familiar search engine paradigm, information on projects, as well as the projects themselves, are discovered and queried using keywords and will be as if performing a Google search. The repository, while focused on single academic unit, can be expended as a campus wide tool, and provides an in house, easily expandable solution to off-the shelf repository solutions