sox9b Is a Key Regulator of Pancreaticobiliary Ductal System Development

The pancreaticobiliary ductal system connects the liver and pancreas to the intestine. It is composed of the hepatopancreatic ductal (HPD) system as well as the intrahepatic biliary ducts and the intrapancreatic ducts. Despite its physiological importance, the development of the pancreaticobiliary ductal system remains poorly understood. The SRY-related transcription factor SOX9 is expressed in the mammalian pancreaticobiliary ductal system, but the perinatal lethality of Sox9 heterozygous mice makes loss-of-function analyses challenging. We turned to the zebrafish to assess the role of SOX9 in pancreaticobiliary ductal system development. We first show that zebrafish sox9b recapitulates the expression pattern of mouse Sox9 in the pancreaticobiliary ductal system and use a nonsense allele of sox9b, sox9bfh313, to dissect its function in the morphogenesis of this structure. Strikingly, sox9bfh313 homozygous mutants survive to adulthood and exhibit cholestasis associated with hepatic and pancreatic duct proliferation, cyst formation, and fibrosis. Analysis of sox9bfh313 mutant embryos and larvae reveals that the HPD cells appear to mis-differentiate towards hepatic and/or pancreatic fates, resulting in a dysmorphic structure. The intrahepatic biliary cells are specified but fail to assemble into a functional network. Similarly, intrapancreatic duct formation is severely impaired in sox9bfh313 mutants, while the embryonic endocrine and acinar compartments appear unaffected. The defects in the intrahepatic and intrapancreatic ducts of sox9bfh313 mutants worsen during larval and juvenile stages, prompting the adult phenotype. We further show that Sox9b interacts with Notch signaling to regulate intrahepatic biliary network formation: sox9b expression is positively regulated by Notch signaling, while Sox9b function is required to maintain Notch signaling in the intrahepatic biliary cells. Together, these data reveal key roles for SOX9 in the morphogenesis of the pancreaticobiliary ductal system, and they cast human Sox9 as a candidate gene for pancreaticobiliary duct malformation-related pathologies

Dynamic Control of Cell Cycle and Growth Coupling by Ecdysone, EGFR, and PI3K Signaling in Drosophila Histoblasts

12 pages, 7 figures.-- PMID: 19355788 [PubMed].-- Supporting information (Suppl. figures S1-S3, movies S1-S7) available at: http://biology.plosjournals.org/perlserv/?request=get-document&doi=10.1371/journal.pbio.1000079#toclink6Regulation of cell proliferation has been extensively studied in cultured cell systems that are characterized by coordinated growth and cell-cycle progression and relatively uniform cell size distribution. During the development of multicellular organisms, however, growth and division can be temporally uncoupled, and the signaling pathways that regulate these growth programs are poorly understood. A good model for analyzing proliferation control in such systems is the morphogenesis of the Drosophila adult abdominal epidermis by histoblasts. These cells undergo a series of temporally regulated transitions during which neither cell size nor division rate is constant. The proliferation of histoblasts during metamorphosis is uniquely amenable to clonal analysis in combination with live imaging. Thereby, we show that abdominal histoblasts, which grow while in G2 arrest during larval stages, enter a proliferative stage in the pupal period that is initiated by ecdysone-dependent string/Cdc25 phosphatase transcription. The proliferating histoblasts have preaccumulated stores of Cyclin E, which trigger an immediate S phase onset after mitosis. These rapid cell cycles lack a G1 phase and result in a progressive reduction of cell size. Eventually, the histoblasts proceed to a stage of slower proliferation that, in contrast to the preceding, depends on epidermal growth factor receptor (EGFR) signaling for progression through the G2/M transition and on insulin receptor/PI3K-mediated signaling for growth. These results uncover the developmentally programmed changes coupling the growth and proliferation of the histoblasts that form the abdominal epidermis of Drosophila. Histoblasts proceed through three distinct stages: growth without division, division without growth, and growth-coupled proliferation. Our identification of the signaling pathways and cell-cycle regulators that control these programs illustrates the power of in vivo time-lapse analyses after clone induction. It sets the stage for the comprehensive understanding of the coordination of cell growth and cell-cycle progression in complex multicellular eukaryotes.[Author summary] A fundamental issue in biology is the question of how the rate of cell division is coupled to cell growth. Coordination of these processes has been studied extensively in cultured cell systems but to a much lesser extent in intact organisms. To study this phenomenon in a physiological setting, we developed a methodology to observe and manipulate cell division and growth in a population of Drosophila abdominal cells called histoblasts. The various developmental stages of histoblast morphogenesis include exit from cell-cycle arrest, initially rapid growth in the absence of cell division, and subsequent coupling of proliferation and growth. We identified several critical developmental signaling pathways (including signaling via ecdysone, the EGF receptor, and PI 3-kinase) that regulate and coordinate cell growth and division cycles during these different types of cell-cycle phenomena. We propose that the internal logic of the Drosophila histoblast system may serve as a basic framework for understanding not only how coordinated cell growth and division operate in a number of other developmental contexts, but also how misregulation of cell growth and division occurs in contexts such as cancer cell populations.NN was supported by a Formación de Profesorado Universitario (FPU) fellowship from the Spanish Ministry of Education and Science (MEC) and CM by the "Juan de la Cierva" MEC program. Work in EM-B's lab is supported by grants of the DGICYT (MEC) and the European Union (EU) (WOUND-STREP Project).Peer reviewe

Microinsurance – Potential for Development in Bulgaria

According to the World Bank 1.5% of the Bulgarian population lives below $1.90 per day. For a population of Bulgaria as of 31st December 2014, comprising 7 202 198 people, this share covers approximately 108 032 people. At the same time, in relation to the implementation of social assistance activities, according to the Social Assistance Act (SAA) and the Regulation on the Implementation of the Social Assistance Act (RISAA), from the begging of 2014 until the end of December of the same year under the Regulation on the Implementation of the Social Assistance Act with one-of, targeted and monthly social benefits in the country, a total of 63 932 persons and families were supported. This fact demonstrates an alarming trend in particular that not a small number of people remain out of the coverage of the publicly organized social assistance system – approximately 44 100 people, who are not eligible for social benefits for various reasons. All this gives us reason to look for alternative solutions to improve social protection, especially to those being absolutely poor in our country. One of these alternatives, which is widespread in the world and unfortunately almost unknown in our country, is microinsurance. The latter has the potential to increase the social security of those who are in extreme poverty and to expand the activity of the insurance companies in Bulgaria

Whole organism high content screening identifies stimulators of pancreatic beta-cell proliferation.

Inducing beta-cell mass expansion in diabetic patients with the aim to restore glucose homeostasis is a promising therapeutic strategy. Although several in vitro studies have been carried out to identify modulators of beta-cell mass expansion, restoring endogenous beta-cell mass in vivo has yet to be achieved. To identify potential stimulators of beta-cell replication in vivo, we established transgenic zebrafish lines that monitor and allow the quantification of cell proliferation by using the fluorescent ubiquitylation-based cell cycle indicator (FUCCI) technology. Using these new reagents, we performed an unbiased chemical screen, and identified 20 small molecules that markedly increased beta-cell proliferation in vivo. Importantly, these structurally distinct molecules, which include clinically-approved drugs, modulate three specific signaling pathways: serotonin, retinoic acid and glucocorticoids, showing the high sensitivity and robustness of our screen. Notably, two drug classes, retinoic acid and glucocorticoids, also promoted beta-cell regeneration after beta-cell ablation. Thus, this study establishes a proof of principle for a high-throughput small molecule-screen for beta-cell proliferation in vivo, and identified compounds that stimulate beta-cell proliferation and regeneration

Modelling pancreatic β-cell inflammation in zebrafish identifies the natural product wedelolactone for human islet protection

Islet inflammation and cytokine production are implicated in pancreatic β-cell dysfunction and diabetes pathogenesis. However, we lack therapeutics to protect the insulin-producing β-cells from inflammatory damage. Closing this clinical gap requires the establishment of new disease models of islet inflammation to facilitate screening efforts aimed at identifying new protective agents. Here, we have developed a genetic model of Interleukin-1β (Il-1β)-driven islet inflammation in zebrafish, a vertebrate that allows for non-invasive imaging of β-cells and in vivo drug discovery. Live imaging of immune cells and β-cells in our model revealed dynamic migration, increased visitation and prolonged macrophage retention in the islet, together with robust activation of NF-κB signalling in β-cells. We find that Il-1β-mediated inflammation does not cause β-cell destruction but, rather, it impairs β-cell function and identity. In vivo, β-cells exhibit impaired glucose-stimulated calcium influx and reduced expression of genes involved in function and maturity. These defects are accompanied by α-cell expansion, glucose intolerance and hyperglycemia following a glucose challenge. Notably, we show that a medicinal plant derivative (wedelolactone) is capable of reducing the immune-cell infiltration while also ameliorating the hyperglycemic phenotype of our model. Importantly, these anti-diabetic properties in zebrafish are predictive of wedelolactone's efficacy in protecting rodent and human islets from cytokine-induced apoptosis. In summary, this new zebrafish model of diabetes opens a window to study the interactions between immune and β-cells in vivo, while also allowing the identification of therapeutic agents for protecting β-cells from inflammation

MODERN DIMENSIONS OF THE POLICIES AND STRATEGIES "ANTIPOVERTY" IN REPUBLIC OF BULGARIA IN THE CONTEXT OF THE EUROPEAN SOCIAL MODEL

В настоящата публикация са разгледани, някои основни проблеми залегнали в разработения проект. Доколко обема позволява засегнати са основните теоретико-концептуални основи на бедността, видовете и функциите и. Акцентът се поставя най вече върху гъвкавостта на трудовия пазар, на икономическата активност и заетост. Обосновани са регионите с най-висока бедност в страната.Разкриват се най-търсените и прилагани програми и мерки за заетост в регионите с най-висока безработица и се акцентира върху тяхната ефективност. Въз основа на мненията на специалистите, занимаващи се с разглежданите проблеми от областите с високо равнище на бедност са направени критични бележки относно ефективността на тяхното използване. Същевременно се поставят и разглеждат проблемите на политиката на социалното подпомагане за намаляване на бедността като се открояват програмите за гарантиран минимален доход и целевото енергийно регулиране с цел снижаване равнището на бедност в най-бедните региони. Some fundamental problems underlined in the project are discussed. In so far as the volume allows, the basic theoretical and conceptual foundations of poverty its functions and types are affected. The focus is primarily on labor market flexibility, on economic activity and employment. The regions with the highest poverty in the country are justified. The most sought and implemented programs and measures for employment with the regions with the highest unemployment rates are disclosed. The emphasis is placed on their effectiveness. Based on the opinions of specialists dealing with the problems of areas with high level of poverty, some critical remarks about the effectiveness of their use are made. At the same time, policy problems of social assistance for poverty reduction are placed and processed. Programs for guaranteed minimum income and target energy assistance carried out to reduce poverty in the poorest regions are highlighted

Dpp Signaling Directs Cell Motility and Invasiveness during Epithelial Morphogenesis

Tissue remodeling in development and disease involves the coordinated invasion of neighboring territories and/or the replacement of entire cell populations. Cell guidance, cell matching, transitions from passive to migratory epithelia, cell growth and death, and extracellular matrix remodeling all impinge on epithelial spreading. Significantly, the extracellular signals that direct these activities and the specific cellular elements and mechanisms regulated by these signals remain in most cases to be identified. To address these issues, we performed an analysis of histoblasts (Drosophila abdominal epithelial founder cells on their transition from a dormant state to active migration replacing obsolete larval epidermal cells (LECs)). We found that during expansion, Decapentaplegic (Dpp) secreted from surrounding LECs leads to graded pathway activation in cells at the periphery of histoblast nests. Across nests, Dpp activity confers differential cellular behavior and motility by modulating cell-cell contacts, the organization and activity of the cytoskeleton, and histoblast attachment to the substrate. Furthermore, Dpp also prevents the premature death of LECs, allowing the coordination of histoblast expansion to LEC delamination. Dpp signaling activity directing histoblast spreading and invasiveness mimics transforming growth factor-beta; and bone morphogenetic proteins` role in enhancing the motility and invasiveness of cancer cells, resulting in the promotion of metastasis