Charakterisierung der funktionellen Bedeutung der mikroRNA-34a während der Entwicklung und der Tumorgenese mittels eines Mausmodells

MikroRNAs (miRNAs) sind kurze, nicht-kodierende RNAs, welche durch sequenzspezifische Interaktion mit mRNAs deren Stabilität und Translation regulieren. miRNAs regulieren eine Reihe wichtiger Funktionen während der Entwicklung, der Differenzierung, der Zellzyklusprogression und der Apoptose. Vorangehende Studien haben eine Beteiligung von miRNAs an der Initiation und der Progression im Krebs aufgezeigt. MiR-34a ist in einigen Tumorentitäten herunterreguliert, so z.B. im Medulloblastom. In primären humanen Medulloblastomen und in den untersuchten Medulloblastomzelllinien war die miR-34a im Vergleich zu normalem humanen Kleinhirngewebe herunterreguliert. Eine miR-34aÜberexpression in vitro reduzierte die Zellviabilität und die Zellproliferation und führte andererseits zum Anstieg der Apoptose-Rate und der Seneszenz. Des Weiteren wurde die Herunterregulierung der miR-34a Zielgene, MYCN, SIRT1 und E2F3, im Western Blot nachgewiesen. Der Effekt der manipulierten miR-34a- Expression in vivo wurde mittels zielgerichteter Transgenese in Mäusen untersucht. Hierfür wurden Mäuse generiert, die eine Deletion im miR-34a Gen aufweisen und somit keine funktionelle miR-34a exprimieren können. MiR-34a-defiziente Mäuse waren lebensfähig und fertil. Um einen Überblick über die physiologische Rolle der miR-34a im adulten Organismus zu bekommen wurden 80 Tiere in einem standardisiertem Screen, der mehr als 300 Parameter umfasst, in der German Mouse Clinic (GMC) phänotypisiert. Die Charakterisierung in der GMC ergab keine phänotypischen Auffälligkeiten in der miR-34a defizienten Maus. In einem etablierten Medulloblastom- Mausmodell, der ND2:SmoA1 Maus, zeigte sich eine tumorgewebsspezifische Suppression der miR-34a. Eine Verkreuzung der miR-34a-defizienten Mäuse mit ND2:SmoA1-Mäusen führte zu einer Beschleunigung der Tumorbildung. Die Tumore wurden morphologisch und auf Proteinebene näher charakterisiert. Interessanterweise waren SIRT1 und n-MYC sehr stark in den Medulloblastomen der doppelt transgenen SmoA1;MiR-34a ko/ko Mäuse exprimiert. Es konnte erstmals gezeigt werden, dass die mikroRNA-34a für die Hirnentwicklung im Normalgewebe nicht essentiell ist, dass ihr Verlust aber in prädisponierten Mäusen die Tumorbildung beschleunigt. Strategien zur Reexpression der miR-34a könnten in Zukunft eine effektive Tumortherapie darstellen

USING CONCEPT MAP ASSESSMENT TO COMPLEMENT TRADITIONAL ASSESSMENT IN THE PHYSICS CLASSROOM

ABSTRACT The issues related to adopting concept map assessment to complement traditional assessment in a secondary 3 physics classroom in Singapore were examined. The 65 participants in the study were all high ability students. Training in concept mapping techniques was integrated into classroom lessons. Students sat for a traditional test before the concept map test on the same lesson units. The construct-a-map task was given with a concept list. The test maps were scored using a scoring method based mainly on the quality of propositions. The results suggest that concept map assessment may be used to complement traditional assessment in This conference proceedings may be used for private study or research purpose only

BET bromodomain protein inhibition is a therapeutic option for medulloblastoma

Medulloblastoma is the most common malignant brain tumor of childhood, and represents a significant clinical challenge in pediatric oncology, since overall survival currently remains under 70%. Patients with tumors overexpressing MYC or harboring a MYC oncogene amplification have an extremely poor prognosis. Pharmacologically inhibiting MYC expression may, thus, have clinical utility given its pathogenetic role in medulloblastoma. Recent studies using the selective small molecule BET inhibitor, JQ1, have identified BET bromodomain proteins, especially BRD4, as epigenetic regulatory factors for MYC and its targets. Targeting MYC expression by BET inhibition resulted in antitumoral effects in various cancers. Our aim here was to evaluate the efficacy of JQ1 against preclinical models for high-risk MYC-driven medulloblastoma. Treatment of medulloblastoma cell lines with JQ1 significantly reduced cell proliferation and preferentially induced apoptosis in cells expressing high levels of MYC. JQ1 treatment of medulloblastoma cell lines downregulated MYC expression and resulted in a transcriptional deregulation of MYC targets, and also significantly altered expression of genes involved in cell cycle progression and p53 signalling. JQ1 treatment prolonged the survival of mice harboring medulloblastoma xenografts and reduced the tumor burden in these mice. Our preclinical data provide evidence to pursue testing BET inhibitors, such as JQ1, as molecular targeted therapeutic options for patients with high-risk medulloblastomas overexpressing MYC or harboring MYC amplifications

Deep sequencing reveals differential expression of microRNAs in favorable versus unfavorable neuroblastoma

Small non-coding RNAs, in particular microRNAs(miRNAs), regulate fine-tuning of gene expression and can act as oncogenes or tumor suppressor genes. Differential miRNA expression has been reported to be of functional relevance for tumor biology. Using next-generation sequencing, the unbiased and absolute quantification of the small RNA transcriptome is now feasible. Neuroblastoma(NB) is an embryonal tumor with highly variable clinical course. We analyzed the small RNA transcriptomes of five favorable and five unfavorable NBs using SOLiD next-generation sequencing, generating a total of >188 000 000 reads. MiRNA expression profiles obtained by deep sequencing correlated well with real-time PCR data. Cluster analysis differentiated between favorable and unfavorable NBs, and the miRNA transcriptomes of these two groups were significantly different. Oncogenic miRNAs of the miR17-92 cluster and the miR-181 family were overexpressed in unfavorable NBs. In contrast, the putative tumor suppressive microRNAs, miR-542-5p and miR-628, were expressed in favorable NBs and virtually absent in unfavorable NBs. In-depth sequence analysis revealed extensive post-transcriptional miRNA editing. Of 13 identified novel miRNAs, three were further analyzed, and expression could be confirmed in a cohort of 70 NBs

Overwintering individuals of the Arctic krill Thysanoessa inermis appear tolerant to short-term exposure to low pH conditions

Areas of the Arctic Ocean are already experiencing seasonal variation in low pH/elevated pCO2 and are predicted to be the most affected by future ocean acidification (OA). Krill play a fundamental ecological role within Arctic ecosystems, serving as a vital link in the transfer of energy from phytoplankton to higher trophic levels. However, little is known of the chemical habitat occupied by Arctic invertebrate species, and of their responses to changes in seawater pH. Therefore, understanding krill’s responses to low pH conditions has important implications for the prediction of how Arctic marine communities may respond to future ocean change. Here, we present natural seawater carbonate chemistry conditions found in the late polar winter (April) in Kongsfjord, Svalbard (79°North) as well as the response of the Arctic krill, Thysanoessa inermis, exposed to a range of low pH conditions. Standard metabolic rate (measured as oxygen consumption) and energy metabolism markers (incl. adenosine triphosphate (ATP) and l-lactate) of T. inermis were examined. We show that after a 7 days experiment with T. inermis, no significant effects of low pH on MO2, ATP and l-lactate were observed. Additionally, we report carbonate chemistry from within Kongsfjord, which showed that the more stratified inner fjord had lower total alkalinity, higher dissolved inorganic carbon, pCO2 and lower pH than the well-mixed outer fjord. Consequently, our results suggest that overwintering individuals of T. inermis may possess sufficient ability to tolerate short-term low pH conditions due to their migratory behaviour, which exposes T. inermis to the naturally varying carbonate chemistry observed within Kongsfjord, potentially allowing T. inermis to tolerate future OA scenarios

Appropriateness criteria for cardiovascular imaging use in heart failure: Report of literature review

The ImagingTask Force appointed by the European Society of Cardiology (ESC) and the European Association of Cardiovascular Imaging (EACVI) identified the need to develop appropriateness criteria for the use of cardiovascular imaging in heart failure as a result of continuously increasing demand for imaging in diagnosis, definition of aetiology, follow-up, and treatment planning. This article presents the report of literature review performed in order to inform the process of definition of clinical indications and to aid the decisions of the appropriateness criteria voting panel. The report is structured according to identified common heart failure clinical scenarios. Published on behalf of the European Society of Cardiology. All rights reserved. © The Author 2014