La Drosophile comme modèle pour l'étude de la maladie d'Alzheimer : rôle de la protéine précurseur Amyloïde dans la mémoire olfactive

Alzheimer's disease (AD) is a neurodegenerative disorder characterized by a progressive deterioration of memory. The amyloid peptide (Aβ), the principal component of senile plaques found in patients’ brains, has been considered as the main cause of memory dysfunction. However, the exact molecular mechanisms that underlie memory decline remain unknown. Aβ is produced by the proteolysis of a transmembrane protein named Amyloid Precursor Protein (APP). It has been suggested that in addition to the accumulation of Aβ, APP loss of function may play a crucial role in the cognitive dysfunction associated with AD, especially at the onset of the disease. Drosophila contains a single APP ortholog APP-like (APPL), that undergoes processing pathways similar to that of APP. We have previously highlighted in young flies the involvement of APPL in associative olfactory memory (Goguel et al., 2011). During my thesis, we sought firstly to identify which form of APPL, among its numerous metabolites, is critical for memory, and secondly, to analyze the effect of promoting the amyloidogenic pathway in the young adult brain. Our results suggest several types of functional interactions between APPL and its metabolites: a positive interaction between the full length membrane and the secreted form - which would underlie implementation of memory under physiological conditions - and a negative interaction between APPL and dAβ - which would rather participate to the progression of the memory decline observed during AD.La maladie d’Alzheimer (MA) est un trouble neurodégénératif qui se manifeste, entre autres, par une détérioration progressive de la mémoire. Le peptide amyloïde (Aβ), composant principal des plaques séniles retrouvées dans le cerveau des patients, a longtemps été considéré comme le principal responsable de ce dysfonctionnement mnésique. Néanmoins, les mécanismes moléculaires à l’origine du déclin de la mémoire restent à ce jour inconnus. Le peptide Aβ est produit par la protéolyse d’une protéine transmembranaire appelée Protéine Précurseur Amyloïde (APP). Il a été proposé qu’en plus de l’effet néfaste de l'accumulation d’Aβ, une perte de fonction d’APP puisse jouer un rôle dans le dysfonctionnement cognitif associé à la MA, en particulier au début de la maladie. La drosophile possède un orthologue d’APP, APP-like (APPL), soumis à deux voies de maturation similaires à celles d’APP. Le laboratoire a mis en évidence l’implication d’APPL chez la mouche adulte dans la mémoire olfactive associative (Goguel et al., 2011). Au cours de ma thèse, nous avons poursuivi deux objectifs : 1) identifier le ou les métabolites d’APPL impliqués dans la mise en place de la mémoire, et 2) analyser l’incidence de la surexpression de la voie amyloïdogénique chez le jeune adulte. Nous avons mis à jour deux types d’interaction fonctionnelle entre APPL et ses métabolites : une interaction positive entre les formes sécrétées et membranaires, qui pourrait sous-tendre la mise en place de la mémoire dans des conditions physiologiques, et une interaction négative entre APPL et dAβ, qui pourrait au contraire participer à l’aggravation des déficits mnésiques observés au cours de l’évolution de la MA

BTX passive sampling to characterise traffic restriction effects

International audienceOn September 22 of each year a large number of French and European towns reduce the motor vehicle traffic in their city centre. Diffusive sampling of benzene, toluene and xylene during periods of 10 hours was used to characterise the improvement of the air quality due to these traffic restrictions. Despite the short sampling duration the use of diffusive sampling led to results consistent with the reduction of the number of motor vehicles and the measured concentrations of carbon monoxide. While under normal traffic conditions most benzene roadside concentrations measured during the day under low wind speed conditions exceeded the European limit value of 5 ug/m3 , these concentrations decreased to an average of 1.5 u.g/m3 under restricted traffic conditions with only 2 out of 10 measurement sites showing concentrations exceeding the French air quality target value of2 ug/m3

Drosophila Melanogaster as a model for Alzheimer disease's study : Role of the Amyloid Precursor Protein in olfactory memory

La maladie d’Alzheimer (MA) est un trouble neurodégénératif qui se manifeste, entre autres, par une détérioration progressive de la mémoire. Le peptide amyloïde (Aβ), composant principal des plaques séniles retrouvées dans le cerveau des patients, a longtemps été considéré comme le principal responsable de ce dysfonctionnement mnésique. Néanmoins, les mécanismes moléculaires à l’origine du déclin de la mémoire restent à ce jour inconnus. Le peptide Aβ est produit par la protéolyse d’une protéine transmembranaire appelée Protéine Précurseur Amyloïde (APP). Il a été proposé qu’en plus de l’effet néfaste de l'accumulation d’Aβ, une perte de fonction d’APP puisse jouer un rôle dans le dysfonctionnement cognitif associé à la MA, en particulier au début de la maladie. La drosophile possède un orthologue d’APP, APP-like (APPL), soumis à deux voies de maturation similaires à celles d’APP. Le laboratoire a mis en évidence l’implication d’APPL chez la mouche adulte dans la mémoire olfactive associative (Goguel et al., 2011). Au cours de ma thèse, nous avons poursuivi deux objectifs : 1) identifier le ou les métabolites d’APPL impliqués dans la mise en place de la mémoire, et 2) analyser l’incidence de la surexpression de la voie amyloïdogénique chez le jeune adulte. Nous avons mis à jour deux types d’interaction fonctionnelle entre APPL et ses métabolites : une interaction positive entre les formes sécrétées et membranaires, qui pourrait sous-tendre la mise en place de la mémoire dans des conditions physiologiques, et une interaction négative entre APPL et dAβ, qui pourrait au contraire participer à l’aggravation des déficits mnésiques observés au cours de l’évolution de la MA.Alzheimer's disease (AD) is a neurodegenerative disorder characterized by a progressive deterioration of memory. The amyloid peptide (Aβ), the principal component of senile plaques found in patients’ brains, has been considered as the main cause of memory dysfunction. However, the exact molecular mechanisms that underlie memory decline remain unknown. Aβ is produced by the proteolysis of a transmembrane protein named Amyloid Precursor Protein (APP). It has been suggested that in addition to the accumulation of Aβ, APP loss of function may play a crucial role in the cognitive dysfunction associated with AD, especially at the onset of the disease. Drosophila contains a single APP ortholog APP-like (APPL), that undergoes processing pathways similar to that of APP. We have previously highlighted in young flies the involvement of APPL in associative olfactory memory (Goguel et al., 2011). During my thesis, we sought firstly to identify which form of APPL, among its numerous metabolites, is critical for memory, and secondly, to analyze the effect of promoting the amyloidogenic pathway in the young adult brain. Our results suggest several types of functional interactions between APPL and its metabolites: a positive interaction between the full length membrane and the secreted form - which would underlie implementation of memory under physiological conditions - and a negative interaction between APPL and dAβ - which would rather participate to the progression of the memory decline observed during AD

Evaluation d'une action de formation sur la contraception hormonale d'urgence chez les adolescents

Introduction : Il existe des besoins importants en matière de contraception d'urgence chez les adolescents, la pilule du lendemain est néanmoins sous-utilisée. Est ce un problème d'information ? Méthodes : évaluation d'une action de formation d'une heure par une résidente en médecine dans 4 classes de troisième. Information encadrée par deux questionnaires identiques. Résultats : amélioration significative des connaissances des élèves dans 10 questions sur 18. L'amélioration des connaissances est d'autant plus importante que les connaissances de base des élèves sont faibles. Discussion : Il y a donc un intérêt à former les jeunes sur la contraception d'urgence à l'école et l'interne en médecine a un rôle à jouer en tant qu'intervenant extérieur, en matière d'éducation à la sexualité. Les modalités de ces interventions restent à définir.NANTES-BU Médecine pharmacie (441092101) / SudocPARIS-BIUM (751062103) / SudocSudocFranceF

Amyloid-β Peptide Exacerbates the Memory Deficit Caused by Amyloid Precursor Protein Loss-of-Function in Drosophila.

The amyloid precursor protein (APP) plays a central role in Alzheimer's disease (AD). APP can undergo two exclusive proteolytic pathways: cleavage by the α-secretase initiates the non-amyloidogenic pathway while cleavage by the β-secretase initiates the amyloidogenic pathway that leads, after a second cleavage by the γ-secretase, to amyloid-β (Aβ) peptides that can form toxic extracellular deposits, a hallmark of AD. The initial events leading to AD are still unknown. Importantly, aside from Aβ toxicity whose molecular mechanisms remain elusive, several studies have shown that APP plays a positive role in memory, raising the possibility that APP loss-of-function may participate to AD. We previously showed that APPL, the Drosophila APP ortholog, is required for associative memory in young flies. In the present report, we provide the first analysis of the amyloidogenic pathway's influence on memory in the adult. We show that transient overexpression of the β-secretase in the mushroom bodies, the center for olfactory memory, did not alter memory. In sharp contrast, β-secretase overexpression affected memory when associated with APPL partial loss-of-function. Interestingly, similar results were observed with Drosophila Aβ peptide. Because Aβ overexpression impaired memory only when combined to APPL partial loss-of-function, the data suggest that Aβ affects memory through the APPL pathway. Thus, memory is altered by two connected mechanisms-APPL loss-of-function and amyloid peptide toxicity-revealing in Drosophila a functional interaction between APPL and amyloid peptide

« Effets interactionnels de l’intégration de l’outil « classe virtuelle » dans un dispositif de formation hybride"

International audienc

« Effets interactionnels de l’intégration de l’outil « classe virtuelle » dans un dispositif de formation hybride"

International audienc

dBACE overexpression exacerbates the memory deficit caused by APPL partial loss-of-function.

<p>Unless indicated (A, w/o RU), flies were fed with RU for 48 h. (A) Flies were submitted to one cycle training and tested 2 h later. <i>Appl</i>^<i>d</i><i>/+;MBSw/+</i> flies show an STM deficit (<i>F</i>_(4,101) = 11.99, ***<i>p</i> < 0.0001, <i>n</i> ≥ 14, Newman-Keuls <i>post-hoc</i>, <i>Appl</i>^<i>d</i><i>/+;MBSw/+</i> vs <i>+</i> *<i>p</i> < 0.05), and <i>Appl</i>^<i>d</i>/+;<i>MBSw</i>/<i>dBACE</i> flies exhibit a STM score significantly lower than the genetic controls (Newman-Keuls <i>post-hoc</i>, <i>Appl</i>^<i>d</i>/+;<i>MBSw</i>/<i>dBACE</i> vs <i>Appl</i>^<i>d</i><i>/+;MBSw/+ ***p <</i> 0.001, <i>Appl</i>^<i>d</i>/+;<i>MBSw</i>/<i>dBACE</i> vs <i>+</i>/<i>dBACE ***p <</i> 0.001). <i>Appl</i>^<i>d</i>/+;<i>MBSw</i>/<i>dBACE</i> flies not fed with RU (w/o RU) display a STM score significantly different from flies of the same genotype fed with RU (Newman-Keuls <i>post-hoc</i>, *<i>p</i> < 0.05), and similar to <i>Appl</i>^<i>d</i>/+;<i>MBSw</i>/<i>+</i> flies (Newman-Keuls <i>post-hoc</i>, <i>p</i> > 0.05). (B) Learning is not affected. To assess learning, flies were tested immediately after one cycle training (<i>F</i>_(2,27) = 0.8522, <i>p</i> = 0.4385, <i>n</i> ≥ 8). (C) Neither shock reactivity (<i>F</i>_(2,21) = 2.747, <i>p</i> = 0.0896, <i>n</i> ≥ 7) nor olfactory acuity (octanol, <i>F</i>_(2,46) = 0.3490, <i>p</i> = 0.7073, <i>n</i> ≥ 15; methylcyclohexanol, <i>F</i>_(2,52) = 2.959, <i>p</i> = 0.0610, <i>n</i> ≥ 17) is impaired. Bars, Mean ± SEM. PI, Performance index. (D, E) Analysis of <i>dBACE</i> and <i>Appl</i> transcription. Total RNA was extracted from <i>MBSw</i>/<i>dBACE</i>, <i>Appl</i>^<i>d</i>/+;<i>MBSw</i>/+ and <i>Appl</i>^<i>d</i>/+;<i>MBSw</i>/<i>dBACE</i> heads. Resulting cDNA was quantified using tubulin (Tub) expression as a reference. Results shown are ratios to the reference. (D) Quantification of <i>dBACE</i> mRNA level (<i>t</i> test, <i>p</i> = 0.8376, <i>n</i> = 4). (E) Quantification of <i>Appl</i> mRNA level (<i>t</i> test, <i>p</i> = 0.2330, <i>n</i> = 3). Bars, Mean ± SEM. ns, not significant.</p

dBACE overexpression in adult MB does not alter memory.

<p>Flies were fed with RU for 48 h before conditioning to induce <i>UAS-dBACE</i> transgene expression. STM assessed 2 h after one training session is not affected. The score of <i>MBSw</i>/<i>dBACE</i> flies is not different from that of the genetic control groups (<i>F</i>_(2,77) = 4.048, *<i>p</i> = 0.0214, <i>n</i> ≥ 24, Newman–Keuls <i>post-hoc</i>, <i>MBSw</i>/<i>dBACE</i> vs +/<i>dBACE p</i> > 0.05, <i>MBSw</i>/<i>dBACE</i> vs <i>MBSw</i>/+ <i>p</i> > 0.05). Bars, Mean ± SEM. PI, Performance index.</p

dAβ expression alters memory only when associated with APPL partial loss-of-function.

<p>Unless indicated (B, w/o RU), flies were fed with RU for 48 h prior to either conditioning or mRNA extraction. (A, B) Flies were submitted to one cycle training and memory was tested 2 h later. (A) <i>MBSw</i>/<i>dAβ</i> flies exhibit a STM score similar to one of the genetic control groups (<i>F</i>_(2,53) = 8.421, ***<i>p</i> = 0.0007, <i>n</i> ≥ 17, Newman-Keuls <i>post-hoc</i>, <i>MBSw</i>/<i>dAβ</i> vs <i>+</i>/<i>dAβ p</i> > 0.05, <i>MBSw</i>/<i>dAβ</i> vs <i>MBSw</i>/<i>+</i> **<i>p</i> < 0.01). (B) <i>Appl</i>^<i>d</i><i>/+;MBSw/+</i> flies show an STM deficit (<i>F</i>_(4,144) = 12.41, ***<i>p</i> < 0.0001, <i>n</i> ≥ 26, Newman-Keuls <i>post-hoc</i>, <i>Appl</i>^<i>d</i><i>/+;MBSw/+</i> vs <i>+</i> **<i>p</i> < 0.01). <i>Appl</i>^<i>d</i>/+;<i>MBSw</i>/<i>dAβ</i> flies display a score significantly decreased compared to the controls (Newman-Keuls <i>post-hoc</i>, <i>Appl</i>^<i>d</i>/+;<i>MBSw</i>/<i>dAβ</i> vs <i>Appl</i>^<i>d</i><i>/+;MBSw/+ **p</i> < 0.01, <i>Appl</i>^<i>d</i>/+; <i>MBSw</i>/<i>dAβ</i> vs <i>+</i>/<i>dAβ ***p</i> < 0.001). <i>Appl</i>^<i>d</i>/+;<i>MBSw</i>/<i>dAβ</i> flies not fed with RU (w/o RU), exhibit scores significantly higher than flies of the same genotype fed with RU (Newman-Keuls <i>post hoc</i>, *<i>p</i> < 0.05), and similar to that of <i>Appl</i>^<i>d</i><i>/+;MBSw/+</i> control flies (Newman-Keuls <i>post hoc</i>, <i>p</i> > 0.05). (C) Learning is not affected. To assess learning, flies were submitted to one cycle training and tested immediately after (<i>F</i>_(2,30) = 1.684, <i>p</i> = 0.2038, <i>n</i> ≥ 9). (D) <i>Appl</i>^<i>d</i>/+;<i>MBSw</i>/<i>dAβ</i> flies exhibit wild-type shock reactivity (<i>F</i>_(2,34) = 0.7100, <i>p</i> = 0.4992, <i>n</i> ≥ 11), as well as wild-type olfactory acuity (octanol, <i>F</i>_(2,34) = 0.0507, <i>p</i> = 0.9506, <i>n</i> ≥ 11; methylcyclohexanol, <i>F</i>_(2,35) = 0.1433, <i>p</i> = 0.8670, <i>n</i> = 12). (E, F) Quantitative PCR analyses. RNA was extracted from <i>MBSw</i>/<i>dAβ</i><i>Appl</i>^<i>d</i>/+;<i>MBSw</i>/+ and <i>Appl</i>^<i>d</i>/+;<i>MBSw</i>/<i>dAβ</i> fly heads. Resulting cDNA was quantified using tubulin (Tub) expression as a reference. Results shown are ratios to the reference. (E) Quantification of <i>dAβ</i> mRNA level. PCR reactions were conducted with primers specific of the <i>UAS-dAβ</i> construct (<i>t</i> test, <i>p</i> = 0.5788, <i>n</i> = 2). (F) Quantification of <i>Appl</i> mRNA level (<i>t</i> test, <i>p</i> = 0.1931, <i>n</i> = 2). Bars, Mean ± SEM. PI, Performance index. ns, not significant.</p