Differential effects of familial Alzheimer’s disease-causing mutations on amyloid precursor protein (APP) trafficking, proteolytic conversion, and synaptogenic activity

The amyloid precursor protein (APP) is a key player in Alzheimer`s disease (AD) and the precursor of the Aβ peptide, which is generated by consecutive cleavages of β- and γ-secretases. Familial Alzheimer’s disease (FAD) describes a hereditary subgroup of AD that represents a low percentage of AD cases with an early onset of the disease. Different APP FAD mutations are thought to have qualitatively different effects on its proteolytic conversion. However, few studies have explored the pathogenic and putative physiological differences in more detail. Here, we compared different FAD mutations, located at the β- (Swedish), α- (Flemish, Arctic, Iowa) or γ-secretase (Iberian) cleavage sites. We examined heterologous expression of APP WT and FAD mutants in non-neuronal cells and their impact on presynaptic differentiation in contacting axons of co-cultured neurons. To decipher the underlying molecular mechanism, we tested the subcellular localization, the endocytosis rate and the proteolytic processing in detail by immunoprecipitation–mass spectrometry. Interestingly, we found that only the Iberian mutation showed altered synaptogenic function. Furthermore, the APP Iowa mutant shows significantly decreased α-secretase processing which is in line with our results that APP carrying the Iowa mutation was significantly increased in early endosomes. However, most interestingly, immunoprecipitation–mass spectrometry analysis revealed that the amino acid substitutions of APP FAD mutants have a decisive impact on their processing reflected in altered Aβ profiles. Importantly, N-terminally truncated Aβ peptides starting at position 5 were detected preferentially for APP Flemish, Arctic, and Iowa mutants containing amino acid substitutions around the α-secretase cleavage site. The strongest change in the ratio of Aβ40/Aβ42 was observed for the Iberian mutation while APP Swedish showed a substantial increase in Aβ1–17 peptides. Together, our data indicate that familial AD mutations located at the α-, β-, and γ-secretase cleavage sites show considerable differences in the underlying pathogenic mechanisms

The Tug1 locus is essential for male fertility

Background: Several long noncoding RNAs (lncRNAs) have been shown to function as central components of molecular machines that play fundamental roles in biology. While the number of annotated lncRNAs in mammalian genomes has greatly expanded, their functions remain largely uncharacterized. This is compounded by the fact that identifying lncRNA loci that have robust and reproducible phenotypes when mutated has been a challenge. Results: We previously generated a cohort of 20 lncRNA loci knockout mice. Here, we extend our initial study and provide a more detailed analysis of the highly conserved lncRNA locus, Taurine Upregulated Gene 1 (Tug1). We report that Tug1 knockout male mice are sterile with complete penetrance due to a low sperm count and abnormal sperm morphology. Having identified a lncRNA loci with a robust phenotype, we wanted to determine which, if any, potential elements contained in the Tug1 genomic region (DNA, RNA, protein, or the act of transcription) have activity. Using engineered mouse models and cell-based assays, we provide evidence that the Tug1 locus harbors three distinct regulatory activities - two noncoding and one coding: (i) a cis DNA repressor that regulates many neighboring genes, (ii) a lncRNA that can regulate genes by a trans-based function, and finally (iii) Tug1 encodes an evolutionary conserved peptide that when overexpressed impacts mitochondrial membrane potential. Conclusions: Our results reveal an essential role for the Tug1 locus in male fertility and uncover three distinct regulatory activities in the Tug1 locus, thus highlighting the complexity present at lncRNA loci

Reconfiguring tissue banking consent through enrichment of a restricted debate

Tissue banks are thought to be an essential resource for medical research in the post-genomic age. Collections of tissue, usually removed in the course of diagnostic or therapeutic procedures, enable laboratory-based epidemiological studies to be carried out, linking abnormalities in the tissue to disease aetiology, prognosis and treatment responsiveness. There are, however, a number of technical, regulatory and ethical concerns that challenge those wishing to engage in tissue banking research. It is becoming increasingly apparent that tissue banking research is not without risk of harms, even though there is no direct physical risk to donors. This is because, in order to be most useful, banked specimens need to be linked to personal information about tissue donors and this poses the risk of inadvertent disclosure of personal─ particularly genetic─ information to those who might exploit such information (eg. insurance companies and employers). Furthermore, the long-term storage of specimens, and the impossibility of predicting all potential types of research programs for which they might be useful, raises the possibility that future projects will be carried out that are unacceptable to some (past) tissue donors. The ethical principles of autonomy and respect for persons demand that research subjects be informed of such risks and of the nature of the research, and that they participate willingly. On the other hand, there is a desire for science to progress unhindered by stringent consent requirements. For these reasons, a debate has emerged in the academic (bioethical and biomedical) literature and in the legal (law reform) sphere over what would constitute adequate consent. Despite an extensive discourse, it is still unclear whether it is permissible to carry out research on archival tissue that was originally taken for diagnostic purposes and whether project-specific (as opposed to open-ended) consent is required for research on tissue collected today. This lack of clarity is of concern to researchers, ethics committees and research subjects, all of whom recognise the importance of tissue banking research, yet fear that current consent procedures may be ethically or legally inadequate. Thus it is important that the consent dilemma be resolved as quickly and definitively as possible. Ongoing controversy and regulatory ambiguity are appropriate when morally contentious issues are at stake, and their existence does not, on its own, signal any flaws in the discourse process. There are, however, two reasons to suspect that the current 'consent to tissue banking' debate, as portrayed in the academic literature and law reform documentation, is problematic. Firstly, the debate appears to be mired in an intractable conflict between those who want to maximise personal autonomy through stringent consent requirements, and those who want the scientific endeavour to progress in a manner that is unconstrained by what are viewed as arduous consent procedures. Secondly, the possible practical options (consent models) being generated by the debate are all limited because they are underpinned by a restricted notion of consent as an individualistic, legalistic and static activity, without consideration of any alternative conceptualisations of consent. Through a thematic analysis of the current 'consent to tissue banking' debate in the academic and law reform literature (Section 3), this thesis shows that debate is essentially occurring between those who see individual autonomy (and stringent consent) as being of primary importance, and those who see unimpeded, market-driven scientific progress as the more important social good, which should not be impeded by unnecessarily stringent consent. Thematic analysis also confirms the existence of the two problems described above, and a failure of those engaged in the debate to reflect on, and challenge, the value-level assumptions underpinning their arguments and those of their opponents. It is argued that this lack of reflection accounts for the two problems: • Firstly, it precludes recognition of the cause of─ and, therefore, ways of resolving─ the intractable conflict at the centre of the debate. Value-level reflection shows that this is a result of the logical and moral conflict within western liberalism, between two modernist goods: individual freedom and scientific progress. • Secondly, it precludes the generation of varied conceptions of consent. Value-level reflection shows that the current range of consent models is restricted to procedures which are individualistic, abstract, static and legalistic, since they are underpinned by western liberal notions of autonomy and scientific progress. This recognition paves the way to consideration of alternative notions of autonomy, scientific progress and, therefore, consent, such as those derived from communitarian and feminist systems of values. A conceptually enriched model of tissue banking consent is then developed (Section 4). This model incorporates dominant (liberal) conceptions of autonomy and scientific progress as well as alternative notions of autonomy and scientific progress espoused by communitarian and feminist systems of values. It is argued that this conceptually-enriched model provides a practical solution to the two problems associated with the standard 'consent to tissue banking' debate. In relation to the philosophically intractable conflict─ or what is termed the 'modernist dilemma'─ between those privileging autonomy and those privileging scientific progress, it shows how the two apparently conflicting 'modernist' goods can both be accommodated at a practical level, thus making the 'consent to tissue banking' debate more tractable and fruitful. In relation to the restricted range of consent models being generated by the current debate, it provides new insights into the ways in which consent might be obtained such that a broader range of community values can be accommodated. More specifically, it stimulates the construction of a model that 1) involves communities, as opposed to merely individuals, in all stages of the scientific process; 2) is flexible and able to adapt consent procedures to specific contexts, rather than predefining procedures in abstract terms; and 3) is transactional and relational rather than static and legalistic. This outcome has interesting philosophical as well as practical implications. It shows that despite apparently unresolved, and possibly irresolvable, normative-level conflicts between the two modernist elements of western liberalism (autonomy and scientific progress), and between liberal, feminist and communitarian systems of values, a multi-perspectival, inclusive, model-building approach provides a practical solution that circumvents these normative-level conflicts

Cryptic Haploid Stages in the Life Cycle of Leathesia marina (Chordariaceae, Phaeophyceae) Under In Vitro Culture

We evaluated the life cycle of Leathesia marina through molecular analyses, culture studies, morphological observations, and ploidy measurements. Macroscopic sporophytes were collected from two localities in Atlantic Patagonia and were cultured under long-day (LD) and short-day (SD) conditions. Molecular identification of the microscopic and macroscopic phases was performed through the cox3 and rbcL genes and the phylogeny was assessed on the basis of single gene and concatenated datasets. Nuclear ploidy of each phase was estimated from the DNA contents of individual nuclei through epifluorescence microscopy and flow cytometry. Molecular results confirmed the identity of the Argentinian specimens as L. marina and revealed their conspecificity with L. marina from New Zealand, Germany, and Japan. The sporophytic macrothalli (2n) released mitospores from plurilocular sporangia, which developed into globular microthalli (2n), morphologically similar to the sporophytes but not in size, constituting a generation of small diploid thalli, with a mean fluorescent nuclei cross-sectional area of 3.21 ± 0.7 μm2. The unilocular sporangia released meiospores that developed two morphologically different types of microthalli: erect branched microthalli (n) with a nuclear area of 1.48 ± 0.07 µm2 that reproduces asexually, and prostrate branched microthalli (n) with a nuclear area of 1.24 ± 0.10 µm2 that reproduces sexually. The prostrate microthalli released gametes in LD conditions, which merged and produced macroscopic thalli with a nuclear cross-sectional area of 3.45 ± 0.09 µm2. Flow cytometry confirmed that the erect and prostrate microthalli were haploid and that the globular microthalli and macrothalli were diploid.Fil: Poza, Ailen Melisa. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Bahía Blanca. Instituto Argentino de Oceanografía. Universidad Nacional del Sur. Instituto Argentino de Oceanografía; ArgentinaFil: Santiañez, Wilfred John E.. Hokkaido University; Japón. University of the Philippines Diliman; FilipinasFil: Croce, Maria Emilia. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Bahía Blanca. Instituto Argentino de Oceanografía. Universidad Nacional del Sur. Instituto Argentino de Oceanografía; Argentina. Universidad Nacional del Sur. Departamento de Biología, Bioquímica y Farmacia; ArgentinaFil: Gauna, Maria Cecilia. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Bahía Blanca. Instituto Argentino de Oceanografía. Universidad Nacional del Sur. Instituto Argentino de Oceanografía; Argentina. Universidad Nacional del Sur. Departamento de Biología, Bioquímica y Farmacia; ArgentinaFil: Kogame, Kazuhiro. Hokkaido University; JapónFil: Parodi, Elisa Rosalia. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Bahía Blanca. Instituto Argentino de Oceanografía. Universidad Nacional del Sur. Instituto Argentino de Oceanografía; Argentin

Silencing of GATA3 defines a novel stem cell-like subgroup of ETP-ALL

This article is distributed under the terms of the Creative Commons Attribution 4.0 International License (http://creativecommons.org/licenses/by/4.0/), which permits unrestricted use, distribution, and reproduction in any medium, provided you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons license, and indicate if changes were made.This work was supported by a research grant from the Deutsche Krebshilfe (Mildred Scheel Professur) and the Wilhelm Sander-Stiftung to CD Baldu

The <i>Ectocarpus</i> genome and the independent evolution of multicellularity in brown algae

Brown algae (Phaeophyceae) are complex photosynthetic organisms with a very different evolutionary history to green plants, to which they are only distantly related1. These seaweeds are the dominant species in rocky coastal ecosystems and they exhibit many interesting adaptations to these, often harsh, environments. Brown algae are also one of only a small number of eukaryotic lineages that have evolved complex multicellularity (Fig. 1).We report the 214 million base pair (Mbp) genome sequence of the filamentous seaweed Ectocarpus siliculosus (Dillwyn) Lyngbye, a model organism for brown algae, closely related to the kelps (Fig. 1). Genome features such as the presence of an extended set of light-harvesting and pigment biosynthesis genes and new metabolic processes such as halide metabolism help explain the ability of this organism to cope with the highly variable tidal environment. The evolution of multicellularity in this lineage is correlated with the presence of a rich array of signal transduction genes. Of particular interest is the presence of a family of receptor kinases, as the independent evolution of related molecules has been linked with the emergence of multicellularity in both the animal and green plant lineages. The Ectocarpus genome sequence represents an important step towards developing this organism as a model species, providing the possibility to combine genomic and genetic2 approaches to explore these and other aspects of brown algal biology further