Suppression of neurodegeneration and increased neurotransmission caused by expanded full-length huntingtin accumulating in the cytoplasm.

Huntington's disease (HD) is a dominantly inherited neurodegenerative disorder caused by expansion of a translated CAG repeat in the N terminus of the huntingtin (htt) protein. Here we describe the generation and characterization of a full-length HD Drosophila model to reveal a previously unknown disease mechanism that occurs early in the course of pathogenesis, before expanded htt is imported into the nucleus in detectable amounts. We find that expanded full-length htt (128Qhtt(FL)) leads to behavioral, neurodegenerative, and electrophysiological phenotypes. These phenotypes are caused by a Ca2+-dependent increase in neurotransmitter release efficiency in 128Qhtt(FL) animals. Partial loss of function in synaptic transmission (syntaxin, Snap, Rop) and voltage-gated Ca2+ channel genes suppresses both the electrophysiological and the neurodegenerative phenotypes. Thus, our data indicate that increased neurotransmission is at the root of neuronal degeneration caused by expanded full-length htt during early stages of pathogenesis.

Leucyl-tRNA synthetase-dependent and -independent activation of a group I intron.

Leucyl-tRNA synthetase (LeuRS) is an essential RNA splicing factor for yeast mitochondrial introns. Intracellular experiments have suggested that it works in collaboration with a maturase that is encoded within the bI4 intron. RNA deletion mutants of the large bI4 intron were constructed to identify a competently folded intron for biochemical analysis. The minimized bI4 intron was active in RNA splicing and contrasts with previous proposals that the canonical core of the bI4 intron is deficient for catalysis. The activity of the minimized bI4 intron was enhanced in vitro by the presence of the bI4 maturase or LeuRS.

Huntingtin interacting proteins are genetic modifiers of neurodegeneration.

Huntington's disease (HD) is a fatal neurodegenerative condition caused by expansion of the polyglutamine tract in the huntingtin (Htt) protein. Neuronal toxicity in HD is thought to be, at least in part, a consequence of protein interactions involving mutant Htt. We therefore hypothesized that genetic modifiers of HD neurodegeneration should be enriched among Htt protein interactors. To test this idea, we identified a comprehensive set of Htt interactors using two complementary approaches: high-throughput yeast two-hybrid screening and affinity pull down followed by mass spectrometry. This effort led to the identification of 234 high-confidence Htt-associated proteins, 104 of which were found with the yeast method and 130 with the pull downs. We then tested an arbitrary set of 60 genes encoding interacting proteins for their ability to behave as genetic modifiers of neurodegeneration in a Drosophila model of HD. This high-content validation assay showed that 27 of 60 orthologs tested were high-confidence genetic modifiers, as modification was observed with more than one allele. The 45% hit rate for genetic modifiers seen among the interactors is an order of magnitude higher than the 1%-4% typically observed in unbiased genetic screens. Genetic modifiers were similarly represented among proteins discovered using yeast two-hybrid and pull-down/mass spectrometry methods, supporting the notion that these complementary technologies are equally useful in identifying biologically relevant proteins. Interacting proteins confirmed as modifiers of the neurodegeneration phenotype represent a diverse array of biological functions, including synaptic transmission, cytoskeletal organization, signal transduction, and transcription. Among the modifiers were 17 loss-of-function suppressors of neurodegeneration, which can be considered potential targets for therapeutic intervention. Finally, we show that seven interacting proteins from among 11 tested were able to co-immunoprecipitate with full-length Htt from mouse brain. These studies demonstrate that high-throughput screening for protein interactions combined with genetic validation in a model organism is a powerful approach for identifying novel candidate modifiers of polyglutamine toxicity.

Juventud y universidad: sujetos y escenarios para el debate crítico y autorreflexivo sobre el consumo de sustancias psicoactivas de uso legal e ilegal / Youth and University: Subjects and Scenarios for Critical and Self-Reflective Debate on the Use of Legal and Illegal Psychoactive Drugs / Juventude e universidade: sujeitos e cenários para o debate crítico e autorreflexivo sobre o consumo de substancias psicoativas de uso legal e ilegal

El objetivo de esta investigación fue la comprensión de los motivos que llevaron a un grupo de jóvenes universitarios a optar por el consumo de sustancias psicoactivas de uso legal e ilegal. Se trató de una investigación cualitativa de estudio de caso, con diseño fenomenológico, en la cual participaron 32 estudiantes. Las técnicas investigativas fueron la observación participante, la observación no participante y los grupos focales. Para el análisis de datos se aplicó la distinción de momentos y reducciones fenomenológicas y criterios de codificación abierta, axial y selectiva. Los principales resultados fueron que las sustancias más consumidas son el alcohol, el tabaco y la marihuana, en tanto que las motivaciones se asocian al ámbito familiar, académico, de la relación entre pares, a la decisión personal, el microtráfico de sustancias de uso ilegal y el comercio de sustancias legales. El consumo de drogas resulta de una red de determinaciones sociales, en relación con la cual, la Universidad podría abrir un debate crítico y autorreflexivo en función del sujeto y no de las sustancias.

The purpose of this research was to understand the reasons that led a group of young university students into the use of legal and illegal psychoactive drugs. This is a qualitative case study research, with a phenomenological design, with the participation of 32 students. The research techniques used were participant observation, non-participant observation, and focus groups. For data analysis we applied moment distinction, phenomenological reductions; and open, axial, and selective codification criteria. The main results show that the most used substances are alcohol, tobacco, and marihuana; regarding motivations, these are associated to family and academic settings, relationship with peers, personal decision, micro-traffic of illegal substances, and commerce of legal substances. Drug use turns into a network of social determinations around which the University could open a critical and self-reflective debate, focused on the subject and not on the substances.

O objetivo desta pesquisa foi a compreensao das motivações que levaram uma turma de jovens universitários optar pelo consumo de substancias psicoativas de uso legal e ilegal. Tratou-se de pesquisa qualitativa de estudo de caso, com desenho fenomenológico, na qual participaram 32 discentes. As técnicas investigativas foram a observação participante, observação nao participante e grupos focais. Para a análise de dados aplicou-se a distinção de momentos e reducoes fenomenológicas e criterios de codificação aberta, axial e seletiva. Os principais resultados foram que substancias mais consumidas sao álcool, tabaco e maconha, entanto que as motivações associam-se ao ámbito familiar, académico, do relacionamento entre pares, decisao pessoal, microtráfico de substancias de uso ilegal e comercio de substancias legais. O consumo de droga resulta de uma rede de determinações sociais, em relação com a qual, a universidade poderia abrir debate crítico e autorreflexivo em função do sujeito e nao das substancias.