Role of the REST/RE-1 system in beta-cell life, function and differentiation

SUMMARYDiabetes is characterized by insulin deficiency that results from the destruction of insulin-secreting pancreatic beta-cells (Type 1), or in part from beta-cell death and insulin secretion defects (Type 2). Therefore, understanding the mechanisms of beta cell neogenesis (to generate unlimited supply of beta cells for T1D transplantation] or identifying the specific genes that favors insulin secretion or beta-cell survival is of great importance for the management of diabetes. The transcriptional repressor RE-1 Silencing Transcription Factor (REST) restricts the expression of a large number of genes containing its binding element, called Repressor Element-1 (RE-1), to neurons and beta cells. To do so, REST is ubiquitously expressed but in neurons and beta cells. To identify these essential genes and their functional significance in beta cells, we have generated transgenic mice that express REST specifically in beta cells under the control of the rat insulin promoter (RIP-REST mice). This resulted in the repression of the RE-1- containing genes in beta cells, and we analyzed the consequences.We first showed that RIP-REST mice were glucose-intolerant because of a defective insulin secretion. To explain this defect, we identified that a subset of the REST target genes were necessary for insulin exocytosis, such as Snap25, Synaptotagmin (Syt) IX, Complexin II, and Ica512, and we further demonstrated that among the identified REST targets, Syt IV and VII were also involved in insulin release. We next analyzed a novel RIP-REST mouse line that featured diabetes and we showed that this defect was due to a major loss of beta-cell mass. To explain this phenotype, we identified REST target genes that were involved in beta-cell survival, such as Ibl, Irs2, Ica512 and Connexin36, and revealed that another REST target, Cdk5r2 is also involved in beta-cell protection. In a third part, we finally suggest that REST may be important for pancreatic endocrine differentiation, since transgenic mice expressing constitutive REST in pancreatic multipotent progenitors show impaired formation of Ngn3-expressing endocrine- committed precursors, and impaired formation of differentiated endocrine cells. Mapping the pattern of REST expression in wild type animals indicates that it is expressed in multipotent progenitors to become then excluded from endocrine cells. Preliminary results suggest that a downregulation of REST would result in relieved expression of at least the Mytl target, favoring subsequent acquisition of the endocrine competence by endocrine precursor cells.Thus, we propose that the REST/RE-1 system is an important feature for beta-cell neogenesis, function and survivalRESUMELe diabète se caractérise par une déficience en insuline qui résulte d'une destruction des cellules bêta (β) pancréatiques sécrétant l'insuline [Type 1], ou à un défaut de sécrétion d'insuline qui peut être associé à la mort des cellules β (Type 2). La compréhension des mécanismes de néogenèse des cellules β, ainsi que l'identification de gènes impliqués dans leur survie et dans le contrôle de la sécrétion d'insuline est donc importante pour le traitement du diabète. Le facteur de transcription de type répresseur, RE-1 Silencing Transcription Factor [REST], contribue à la spécificité d'expression dans les neurones et les cellules β, d'un grand nombre de gènes portant son motif de fixation, le Repressor Element-1 (RE-1). Pour cela, REST est exprimé dans toutes les cellules, sauf dans les neurones et les cellules β. Afin d'identifier les gènes cibles de REST ainsi que leur fonction au sein de la cellule β, nous avons généré des souris transgéniques qui expriment REST spécifiquement dans ces cellules, sous la dépendance du promoteur de l'insuline (souris RIP-REST]. Cette expression ectopique de REST a permis de diminuer l'expression des gènes contrôlés par REST, et d'en analyser les conséquences. Nous avons montré que les souris RIP-REST étaient intolérantes au glucose et que ceci était du à un défaut de sécrétion d'insuline. Pour expliquer ce phénotype, nous avons mis en évidence le fait que des gènes cibles de REST codent pour des protéines importantes pour l'exocytose de l'insuline, comme SNAP25, Synaptotagmin (Syt) IX, Complexin II ou ICA512. De plus, nous avons découvert deux nouvelles cibles de REST impliquées dans la sécrétion d'insuline, Syt IV et Syt VII. Par la suite, nous avons démontré qu'une nouvelle lignée de souris RIP-REST étaient atteintes d'un diabète sévère à cause d'une perte massive des cellules β. La disparition de ces cellules a été expliquée par l'identification de gènes cibles de REST impliqués dans la survie des cellules β, comme Ibl, Irs2, Ica512 ou la Connexine36. De plus, nous avons découvert qu'une nouvelle cible, Cdk5r2, était aussi impliquée dans la survie des cellules β. Dans une dernière partie, nous suggérons, grâce à l'analyse de nouvelles souris transgéniques exprimant constitutivement REST dans les cellules progénitrices du pancréas embryonnaire, que REST empêche la formation des précurseurs de cellules endocrines ainsi que la différenciation de ces cellules. L'analyse de l'expression de REST au cours du développement embryonnaire du pancréas indique que la diminution de l'expression de REST conduit en partie, à l'induction d'un de ses gènes cible Mytl, qui favorise la formation de précurseurs endocrines. Nous proposons donc que le système REST/RE-1 est important pour la génération, la fonction et la survie des cellules β.

Wave competition in excitable modulated media.

The propagation of an initially planar front is studied within the framework of the photosensitive Belousov-Zhabotinsky reaction modulated by a smooth spatial variation of the local front velocity in the direction perpendicular to front propagation. Under this modulation, the wave front develops several fingers corresponding to the local maxima of the modulation function. After a transient, the wave front achieves a stationary shape that does not necessarily coincide with the one externally imposed by the modulation. Theoretical predictions for the selection criteria of fingers and steady-state velocity are experimentally validated.

Food for thought: the importance of glucose and other energy substrates for sustaining brain function under varying levels of activity.

The brain requires a constant and substantial energy supply to maintain its main functions. For decades, it was assumed that glucose was the major if not the only significant source of energy for neurons. This view was supported by the expression of specific facilitative glucose transporters on cerebral blood vessels, as well as neurons. Despite the fact that glucose remains a key energetic substrate for the brain, growing evidence suggests a different scenario. Thus astrocytes, a major type of glial cells that express their own glucose transporter, play a critical role in coupling synaptic activity with glucose utilization. It was shown that glutamatergic activity triggers an enhancement of aerobic glycolysis in this cell type. As a result, lactate is provided to neurons as an additional energy substrate. Indeed, lactate has proven to be a preferential energy substrate for neurons under various conditions. A family of proton-linked carriers known as monocarboxylate transporters has been described and specific members have been found to be expressed by endothelial cells, astrocytes and neurons. Moreover, these transporters are subject to fine regulation of their expression levels and localization, notably in neurons, which suggests that lactate supply could be adjusted as a function of their level of activity. Considering the importance of energetics in the aetiology of several neurodegenerative diseases, a better understanding of its cellular and molecular underpinnings might have important implications for the future development of neuroprotective strategies.

Cholesterol transport from late endosomes to the Golgi regulates t-SNARE trafficking, assembly, and function

Cholesterol regulates plasma membrane (PM) association and functioning of syntaxin-4 and soluble N-ethylmaleimide-sensitive fusion protein 23 (SNAP23) in the secretory pathway. However, the molecular mechanism and cellular cholesterol pools that determine the localization and assembly of these target membrane SNAP receptors (t-SNAREs) are largely unknown. We recently demonstrated that high levels of annexin A6 (AnxA6) induce accumulation of cholesterol in late endosomes, thereby reducing cholesterol in the Golgi and PM. This leads to an impaired supply of cholesterol needed for cytosolic phospholipase A2 (cPLA2) to drive Golgi vesiculation and caveolin transport to the cell surface. Using AnxA6-overexpressing cells as a model for cellular cholesterol imbalance, we identify impaired cholesterol egress from late endosomes and diminution of Golgi cholesterol as correlating with the sequestration of SNAP23/syntaxin-4 in Golgi membranes. Pharmacological accumulation of late endosomal cholesterol and cPLA2 inhibition induces a similar phenotype in control cells with low AnxA6 levels. Ectopic expression of Niemann-Pick C1 (NPC1) or exogenous cholesterol restores the location of SNAP23 and syntaxin-4 within the PM. Importantly, AnxA6-mediated mislocalization of these t-SNAREs correlates with reduced secretion of cargo via the SNAP23/syntaxin-4¿dependent constitutive exocytic pathway. We thus conclude that inhibition of late endosomal export and Golgi cholesterol depletion modulate t-SNARE localization and functioning along the exocytic pathway.

Wave competition in excitable modulated media.

The propagation of an initially planar front is studied within the framework of the photosensitive Belousov-Zhabotinsky reaction modulated by a smooth spatial variation of the local front velocity in the direction perpendicular to front propagation. Under this modulation, the wave front develops several fingers corresponding to the local maxima of the modulation function. After a transient, the wave front achieves a stationary shape that does not necessarily coincide with the one externally imposed by the modulation. Theoretical predictions for the selection criteria of fingers and steady-state velocity are experimentally validated.

Potassium supply to cotton roots as affected by potassium fertilization and liming

Cotton (Gossypium hirsutum) is known to have a high requirement for K and to be very sensitive to low soil pH. Most of K reaches plant roots by diffusion in the soil. As K interacts with Ca and Mg, liming can interfere in K movement in the soil, affecting eventually the plant nutrition. The objective of this work was to study the effect of dolomitic lime and 0, 15, 30, 45 and 60 g kg-1 of K on the supply of K to cotton roots. Cotton plants were grown up to 40 days in 5 L pots containing a Dark Red Latosol (Typic Haplusthox) with 68% and 16% of sand and clay, respectively. There was an increase in dry matter yields and in K accumulation due to K fertilization. Root interception of soil K was also increased by K application, but was not affected by lime. Mass flow and diffusion increased linearly with K levels up to 60 mg kg-1, in pots with lime. In pots without lime the amount of K reaching the roots by diffusion increased up to 45 mg kg-1, but decreased at the highest K level. Accordingly, there was more K reaching the roots through mass flow at the highest K level. This happened because there were more fine roots in pots without lime, at the highest K level. As the roots grew closer, there was a stronger root competition leading to a decrease in the amount of K diffused to cotton roots.

Height distributions of Scots pine sapling stands affected by retained tree and edge stand competition

Abstract

The evolution ofRussian power industry from monopoly to market operation

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Laiteohjauksessamuodostuvan informaation jalostamisen mahdollisuudet

Teollisuuden automaatiojärjestelmät digitalisoituvat, samalla niiden tuottaman reaaliaikaisen datan määrä kasvaa ja etenkin sen saatavuus helpottuu. Samanaikaisesti laitevalmistajan liiketoimintamallit ovat muuttumassa perinteisestä konevalmistuksesta kohti palveluntarjontaa. Muuttuneessa tilanteessa laitteiden ohjauksessa käytettäviltä järjestelmiltä vaaditaan uusia ominaisuuksia. Informaation käsittely ja jalostaminen muodostuvat tärkeiksi kilpailu-tekijöiksi. Kirjallisuusosassa on tarkasteltu, miten data jalostuu informaatioksi ja siitä edelleen tietämykseksi. Työssä myös selvitetään, miten niitä voidaan hyödyntää liiketoiminnassa. Samalla perehdytään teollisuudesta löytyviin informaatio- ja tietämysjärjestelmiin. Kokeellisessa osassa esitellään toimiva tiedonkeruu- ja raportointijärjestelmä ja tutkitaan, miten sitä tulisi kehittää, jotta se sopisi paremmin muuttuviin liiketoimintamalleihin. Lopputuloksena kehitettiin mallijärjestelmä, jolla pystytään täyttämään laitevalmistajan ja loppukäyttäjän muuttuneet informaatiotarpeet osana laiteohjausta.

Dynamic arrest in polymer melts: competition between packing and intramolecular barriers

We present molecular dynamics simulations of a simple model for polymer melts with intramolecular barriers. We investigate structural relaxation as a function of the barrier strength. Dynamic correlators can be consistently analyzed within the framework of the mode coupling theory of the glass transition. Control parameters are tuned in order to induce a competition between general packing effects and polymer-specific intramolecular barriers as mechanisms for dynamic arrest. This competition yields unusually large values of the so-called mode coupling theory exponent parameter and rationalizes qualitatively different observations for simple bead-spring and realistic polymers. The systematic study of the effect of intramolecular barriers presented here also establishes a fundamental difference between the nature of the glass transition in polymers and in simple glass formers.

Hankintariskienhallinta Suomen IVD-teollisuudessa

Kansainvälinen ja kiristyvä kilpailu on muuttanut yritysten liiketoimintaympäristöä yhä monimutkaisemmaksi ja riskialttiimmaksi. Yritysten keskittyessä yhä syvemmin omaan ydinosaamiseensa on ulkoisten resurssien hallinnan merkitys korostunut. Työnjakoa syventämällä tavoitellaan parempaa joustavuutta, ajanhallintaa sekä kustannustehokkuutta. Myös hankintatoimen tehtävät ja vastuualueet muuttuvat ennakoivampaan ja riskialttiimpaan suuntaan. Modernin hankintatoimen on kyettävä tunnistamaan, analysoimaan ja hallitsemaan riskejä yhä pirstaloituneemmista lähteistä ja muodoista. Proaktiivinen hankintatoimi osallistuu yrityksen strategiseen suunnitteluun ja riskienhallintaan. Hankintariskit voidaan luokitella seuraaviin kymmeneen riskiluokkaan: keskeytymisriskit, saatavuusriskit, hintariskit, varasto- ja aikatauluriskit, teknologiariskit, luottamuksellisen tiedon vuotoriskit, laaturiskit, konfiguraatioriskit, opportunismiriskit sekä riippuvuusriskit. Tässä tutkimuksessa hankintariskienhallintaa tarkastellaan hankintastrategian valinnan näkökulmasta. Hankintastrategian yksi elementti on toimittajasuhteen ja toimittajien lukumäärän valinta. Tilanteesta riippuen yhteistyöstrategialla tai perinteisellä kilpailuttamisella voidaan tavoitella parempaa riskienhallintaa. Yhteistyöstrategioita ovat eri tasoiset kumppanuussuhteet ja liittoutumat, jolloin suhde toimittajaan on syvä ja luottamuksellinen hyödyttäen aidosti molempia osapuolia. Riskienhallinnan näkökulmasta yhteistyöstrategia soveltuu parhaiten tilanteissa, joissa toimittajista on pitkä kokemus sekä hankintanimikkeen tuottama arvo on merkittävä. Kilpailuttamisstrategia eli hankintojen toteuttaminen usealta toimittajalta vaatii ostavalta organisaatiolta tehokkaasti hyödynnettynä suurempia resursseja kuin yhteistyöstrategian käyttö. Kilpailuttaminen soveltuu usein parhaiten silloin, kun hankintanimikkeet ovat tavanomaisia ja vaihtoehtoisia hankintalähteitä on runsaasti. Lisäksi usean toimittajan käyttö suojaa materiaalivirran katkoksilta sekä lisää hankintamarkkinoiden tuntemusta. Empiirisessä tutkimusosassa tutkitaan, miten soveltuviksi riskienhallintamenetelmiksi erilaiset hankintastrategiat koetaan Suomen IVD-teollisuudessa. Lisäksi tunnistetaan Suomen IVD-teollisuudessa merkittävimmiksi koetut hankintariskiluokat sekä selvitetään millä organisaation tasolla hankintariskienhallinta pääasiassa suoritetaan. Lisäksi selvitetään, millä menetelmin hankintariskejä pääasiassa analysoidaan.

Supply Risk Management in Pharmaceutical

Fast development in the operating environment and fierce competition have driven companies to pursue efficiency and success through lean and global supply chains. At the same time overall uncertainty has increased in the business environment and supply chains have become a priority in risk management since their vulnerability may endanger business continuity. Although risk management should start at procurement strategy development phase, proactive contingency planning is also essential because it enables correct reaction and fast changes in process execution in the case of risk realization. This thesis is a case study conducted in the pharmaceutical industry where purchasing and materials management organizations face a number of challenges and limitations that have to be considered in supply risk management. The goal of the study was to discuss the operating environment, and identify and analyze supply risks and potential risk management practices. The study was concluded with suggestions for purchasing strategy development that take risk management considerations into account. This copy is the public version of the thesis.

Strategic supply chain alignment to customer buying behavior

In search for competitive advantage, designing and managing supply chain networks have become a necessary competence for organizations. The target of this thesis is to answer a question, how to design a multiple supply chain network. The purpose is to study, what kind of different supply chain designs exist and, how to choose appropriate supply chain designs for a company. In the thesis, the focus is on the supply chain alignment to customers, more specifically to customer buying behavior. The research method was a case study. A framework for measuring customer buying behavior was developed based on the literature and it was used in the study of customer buying behavior in the case environment. In the case company structured interviews and data records were used as sources of evidence. Persons working in the customer-interface were interviewed face-to-face and through an e-mail questionnaire. When analyzing the data, a Quality function deployment matrix was used as one analysis method. As a result of the thesis, supply chain network of the case company is proposed to be divided into three separate supply chains, which focus on different areas and they could be called lean, agile and continuous replenishment supply chains. In conclusion, in the supply chain alignment to customer buying behavior several aspects have to be studied from different perspectives. According to the results, a multiple supply chain strategy is recommended to be implemented in the case company, since the diversity of the customer needs cannot be managed efficiently through a single supply chain.

Assessment of purchasing maturity in spare parts supply chain

To describe the change of purchasing moving from administrative to strategic function academics have put forward maturity models which help practitioners to compare their purchasing activities to industry top performers and best practices. However, none of the models aim to distinguish the purchasing maturity from the after-sales point of view, even though after-sales activities are acknowledged as a relevant source of revenue, profit and competitive advantage in most manufacturing firms. The maturity of purchasing and supply management practices have a large impact to the overall performance of the spare parts supply chain and ultimately to the value creation and relationship building for the end customer. The research was done as a case study for a European after-sales organization which is part of a globally operating industrial firm specialized in heavy machinery. The study mapped the current state of the purchasing practices in the case organization and also distinguished the relevant areas for future development. The study was based on the purchasing maturity model developed by Schiele (2007) and investigated also how applicable is the maturity model in the spare parts supply chain context. Data for the assessment was gathered using five expert interviews inside the case organization and other parties involved in the company’s spare parts supply chain. Inventory management dimension was added to the original maturity model in order to better capture the important areas in a spare parts supply chain. The added five questions were deduced from the spare parts management literature and verified as relevant areas by the case organization’s personnel. Results indicate that largest need for development in the case organization are: better collaboration between sourcing and operative procurement functions, use of installed base information in the spare parts management, training plan development for new buyers, assessment of aligned KPI’s between the supply chain parties and better defining the role of after-sales sourcing. The purchasing maturity model used in this research worked well in H&R Leading, Controlling and Inventory Management dimensions. The assessment was more difficult to conduct in the Supplier related processes, Process integration and Organizational structure –dimensions, mainly because the assessment in these sections would for some parts require more company-wide assessment. Results indicate also that the purchasing maturity model developed by Schiele (2007) captures the relevant areas in the spare parts supply as well.

Modeling light interception and distribution in mixed canopy of common cocklebur (Xanthium stramarium) in competition with corn

The aim of this study was to model light interception and distribution in the mixed canopy of Common cocklebur (Xanthium stramarium) with corn. An experiment was conducted in factorial arrangement on the basis of randomized complete blocks design with three replications in Gonabad in 2006-2007 and 2007-2008 seasons. The factors used in this experiment include corn density of 7.5, 8.5 and 9.5 plants per meter of row and density of Common cocklebur of zero, 2, 4, 6 and 8 plants per meter of row. INTERCOM model was used through replacing parabolic function with triangular function of leaf area density. Vertical distribution of the species' leaf area showed that corn has concentrated the most leaf area in layer of 80 to 100 cm while Common cocklebur has concentrated in 35-50 cm of canopy height. Model sensitivity analysis showed that leaf area index, species' height, height where maximum leaf area is seen (hm), and extinction coefficient have influence on light interception rate of any species. In both species, the distribution density of leaf area at the canopy length fit a triangular function, and the height in which maximum leaf area was observed was changed by change in density. There was a correlation between percentage of the radiation absorbed by the weed and percentage of corn seed yield loss (r² = 0.89). Ideal type of corn was determined until the stage of tasseling in competition with weed. This determination indicates that the corn needs more height and leaf area, as well as less extinction coefficient to successfully fight against the weed.