No description available.

No description available.

Centrosomes are microtubule-based organelles composed of two centrioles and peri-centriolar material, involved in the formation and organization of the mitotic spindle, serving as microtubule-organizing center and involved in ciliogenesis. Supernumerary centrosomes are detrimental for cell physiology and activate the PIDDosome, a multi-protein complex that serves as a platform for the activation of Caspase-2, composed of: PIDD1, RAIDD and Caspase-2 itself. Caspase-2’s preferred cleavage site based on peptide screening is VDVAD, however Caspase-2, when activated via the PIDDosome, cleaves its bona fide substrate MDM2 (negative p53 regulator) in the FDVPD sequence. Here, I present evidence for VDVADase activity in apoptotic cells lacking Caspase-2, which suggests that this cleavage site is not Caspase-2 specific when the Caspase-2 activation occurs via the PIDDosome. In order to investigate if the mode of activation of Caspase-2 determines its substrate specificities I performed a Caspase-2 rescue experiment and introduced several mutations affecting the Caspase-2 autoproteolytic-processing. Furthermore, I present evidence that exogenous Caspase-2 is able to form the PIDDosome and cleaves MDM2 but when key autoproteolytic sites are mutated no MDM2 cleavage is detectable. Supernumerary centrosomes also accumulate upon overexpression of PLK4 (a kinase regulator of the centriole duplication). Immunofluorescence images of cells overexpressing PLK4 were taken following the centrioles quantification over time. Consequently, a large amount of image data was accumulated, which necessitated the development of a semi-automated pipeline for centrioles counting. This pipeline was generated using the image processing and analysis tool ImageJ and the deep learning segmentation tool MitoS together with the pretrained MitoSegNet model, which was finetuned to count centrioles stained against different centrosomal epitopes, namely Centrin 1, γ-Tubulin and ANKRD26. This semi-automated method of centrioles quantification is easy to use, reproducible and faster than manual quantification. Using this pipeline to quantify centrioles in p53, SCLT1 or ANKRD26 lacking cells we demonstrate accumulation of supernumerary centrosomes in these cells similar to parental cells. / I centrosomi sono organelli cellulari a base di microtubuli, composti da due centrioli e dal materiale pericentriolare che li circonda. I centrosomi sono coinvolti nell'organizzazione dei microtubuli, nella formazione del fuso mitotico e nella ciliogenesi. I centrosomi soprannumerari sono dannosi per la fisiologia cellulare e attivano il PIDDosoma, un complesso multiproteico, composto da PIDD1, RAIDD e Caspasi-2, che funge da piattaforma per l'attivazione della caspasi stessa. Il sito preferenziale di proteolisi di Caspasi-2 è stato individuato tramite screening peptidico nella sequenza VDVAD. Nonostante ciò, quando attivata tramite il PIDDosoma, Caspasi-2 scinde il suo substrato di elezione MDM2 (regolatore negativo di p53) a livello della sequenza FDVPD. In questa tesi presento evidenze di attività VDVAD-asica in cellule apoptotiche prive di Caspasi-2, suggerendo che questo sito di taglio non sia specifico di Caspasi-2 quando la sua attivazione avviene tramite il PIDDosoma. Al fine di indagare se la modalità di attivazione della proteasi determina le sue specificità di substrato, ho eseguito esperimenti di complementazione di Caspasi-2 facendo uso di diversi mutanti che influenzano il suo processamento autoproteolitico. Inoltre, presento prove che Caspasi-2 esogena è in grado di assemblare il PIDDosoma e proteolizzare MDM2 ma quando i suoi siti chiave di autoproteolisi sono mutati non è rilevabile il taglio di MDM2. I centrosomi soprannumerari si accumulano anche in caso di sovraespressione di PLK4 (chinasi regolatrice della duplicazione dei centrioli). Immagini di immunofluorescenza di cellule che sovraesprimono PLK4 sono state acquisite seguendo la cinetica di accumulo dei centrioli nel tempo. Di conseguenza, l’ingente mole di dati generati ha reso necessario lo sviluppo di una procedura semiautomatica per la conta dei centrioli. Questa pipeline è stata generata utilizzando il programma di elaborazione e analisi di immagini ImageJ e il programma di segmentazione basato su deep learning MitoS, insieme al modello MitoSegNet, che è stato affinato per la conta dei centrioli evidenziati tramite immunofluorescenza diretta contro diversi epitopi centrosomiali, ossia: Centrin 1, γ-Tubulina e ANKRD26. Questo metodo semiautomatico di quantificazione dei centrioli è facile da usare, riproducibile e più veloce della quantificazione manuale. Utilizzando questa procedura per quantificare i centrioli nelle cellule prive di p53, SCLT1 o ANKRD26, dimostriamo che l'accumulo di centrosomi soprannumerari in queste cellule è simile a quello riscontrato nelle cellule parentali.

Mémoire numérisé par la Direction des bibliothèques de l'Université de Montréal.

INTRODUÇÃO: As doenças retinianas associadas à neovascularização, tais como a degeneração macular relacionada à idade e as retinopatias diabética e da prematuridade são as principais e mais importantes causas da cegueira em todo o mundo. Nos últimos anos, injeções intravítreas de fármacos com ação antiangiogênica, como o bevacizumabe (BVZ), têm sido de grande valia tanto em pacientes na fase adulta quanto nos recém-natos. Todavia, estudos experimentais in vitro e in vivo sugerem que essas drogas promovam efeitos adversos sobre alguns processos celulares, interferindo diretamente em mecanismos fisiológicos que mantém a homeostase do tecido retiniano, incluindo os mecanismos de proliferação, diferenciação e morte celular. OBJETIVO: investigar o efeito do BVZ nos processos de transcrição e tradução de marcadores da gliose: GFAP e vimentina, de morte celular, caspase-3 e beclina-1, e dos proteoglicanos relacionados à manutenção e desenvolvimento de tecido retiniano: neurocam, fosfacam e sindecam-3. MÉTODOS: Dois modelos experimentais foram usados nesse estudo: 1) linhagem celular de Müller de Glia humana adulta (MIO-M1), cultivada em meio de cultura D-MEM na presença e ausência de BVZ por 12 e 24 horas nas concentrações de 0,25 mg/mL e 0,50 mg/mL e 2) explantes de retinas de ratos 2 dias pós-nascidos submetidos à 0,50 mg/mL da droga por 48 horas. Durante este período foram mantidos a 5% de dióxido de carbono à temperatura de 37°C. A análise de proteínas foi realizada por imunocitohistoquímica e Western Blotting e a expressão de RNAm, pela reação em cadeia da polimerase em tempo real (PCR Real Time). Foi utilizado o Teste de ANOVA - fator único para a comparação entre os grupos controle e tratados com BVZ de um mesmo período (12h ou 24h) e o teste t de Student para a comparação entre as mesmas concentrações de 12h e 24h, e para a comparação entre os grupos controle e tratado com BVZ dos explantes (p < 0,05). RESULTADOS: Nas células MIO-M1, o BVZ, aumentou a expressão gênica e diminui a tradução de VEGF na concentração de 0,50 mg/mL em 24h comparado a 12h. Para o GFAP, houve um aumento da transcrição em 0,50 mg/mL em 24h comparado a 12h e aos outros grupos em 24h. Entretanto, houve diminuição da tradução para estes mesmos períodos e condições. Para a vimentina, houve aumento na transcrição em 0,50 mg/mL após 24h. Os achados de beclina-1 revelaram uma diminuição da transcrição e tradução em 0,25 mg/mL em 24h comparado a 12h. A transcrição entre os grupos do mesmo período aumentou nos grupos tratados com BVZ tanto em 12h quanto em 24h. A tradução da beclina-1 diminuiu em 0,25 mg/mL, mas aumentou em 0,50 mg/mL em 24h em relação à 12h. A comparação entre os grupos de 24h revelou aumento da tradução em 0,50 mg/mL. Para a caspase-3, houve diminuição da transcrição em 0,25 mg/mL e 0,50 mg/mL em 24h em relação a 12h e entre nos grupos tratados com BVZ em 24h. A tradução revelou um aumento em 0,50 mg/mL em 24h em relação a 12h. No fosfacam, houve diminuição da transcrição em 0,50 mg/mL em 24h comparado a 12h e entre os grupos tratados com BVZ e controles para 12h e 24h. A transcrição de neurocam diminuiu em 0,25 mg/mL e 0,50 mg/mL em 24h comparado a 12h e entre os grupos tratados com BVZ e controles em 12h e 24h. A tradução aumentou em 0,50 mg/mL em 24h em relação a 12h, mas diminuiu entre os grupos em 24h. Nos explantes, a transcrição e tradução de VEGF diminuiram no grupo tratado com BVZ após 48h. CONCLUSÃO: Nossos resultados relacionados às células MIO-M1 e ao explante de ratos, in vitro, nos permitem aventar o possível comprometimento ocasionado pela depleção do VEGF pelo BVZ na homeostase do tecido retiniano, in vivo, interferindo nas moléculas envolvidas na morte e diferenciação celular e na neuroproteção em indivíduos em fase adulta e recém-nato / Backgraound: Vasoproliferative retinal disorders such as age-related macular, degeneration, diabetic retinopathy and retinopathy of prematurity are major causes of blindness in the world. In recent years, intravitreal injections of drugs with antiangiogenic action, as bevacizumab, have been very useful for both patients in adulthood and in newborns. However, experimental studies, in vivo and in vitro, suggest that antiangiogenic drugs may promote side effects in cellular proceedings, interfering directly in physiological mechanisms of cellular proliferation, differentiation and death. POURPOSE: Investigate the bevacizumab effects in transcription and translation processes of gliosis, GFAP and vimentin, cellular death markers, caspase-3 and beclin-1, and proteoglycans involved in retinal tissue maintenance and development, neurocan, phosphacan and syndecan-3. METHODS: Two experimental models were used on this research: cellular lineage of adult and human Müller glial cell(MIO-M1) were cultivated on D-MEM medium with 0,25 and 0,50 mg/mL bevacizumab for 12 and 24 hours, and two days old rat retinal explants submitted to 0,50 mg/mL for 48 hours. During this period were stored in laboratory ovens at 5% carbon dioxide pressure and 37 °C average temperature. Molecular techniques were used to evaluate gene expression and protein content. Protein assessments were performed by immunocytochemistry and western blotting analysis, while Real Time PCR was used to measure mRNA content. ANOVA tests one factor were applied to compare the control and BVZ groups of the same period (12h or 24h) and t test from Student to compare the same conditions of 12h and 24h, and to compare the control and BVZ retinal explants groups (p<0.05). RESULTS: At MIO-M1 cells, BVZ increased the gene expression and reduced the translation of VEGF at concentration of 0.50 mg / mL in 24 hours compared to 12 hours. For GFAP, there was an increase of transcription at 0.50 mg / mL in 24 hours compared to 12 hours and to the other groups at 24 hours. However, there was a decrease in translation for these same periods and conditions. For vimentin, there was an increase in transcription at 0.50 mg / mL after 24 hours. The beclin-1 findings revealed a decrease of transcription and translation at 0.25 mg / ml compared at 24 h compared to 12h. Transcription among groups increased in BVZ treated groups at 12h and 24h. The translation of beclin-1 decreased at 0.25 mg / ml, but increased at 0.50 mg / mL at 24 hours compared to 12 hours. The comparison between the groups at 24h revealed an increased in translation at 0.50 mg / mL. For caspase-3, there was a decrease in transcription at 0.25 mg / ml and 0.50 mg / ml at 24 compared to 12 hours and among BVZ treated groups at 24h. Translation revealed an increase at 0.50 mg / mL at 24 hours compared to 12 hours. For fosfacam, there was a decreased in transcription at 0.50 mg / mL in 24 hours compared to 12 hours and among BVZ treated groups and controls at 12h and 24h. The transcription of neurocam decreased at 0.25 mg / ml and 0.50 mg / ml at 24 hours compared to 12 hours and among BVZ treated groups and controls at 12h and 24h. Translation increased at 0.50 mg / mL at 24 compared to 12 hours, but decreased among the groups at 24 hours. For explants, transcription and translation of VEGF decreased in the BVZ group treated after 48h. CONCLUSION: Our results related to the MIO-M1 cells and explants of rats,in vitro, allow us to suggest the possible impairment caused by depletion of VEGF by BVZ in the homeostasis of retinal tissue, in vivo, interfering in the molecules involved in cell death and cell differentiation and neuroprotection in individuals in adulthood and newborns

Die rasanten Fortschritte in der neonatalen Intensivmedizin haben zwar die Ueberlebenschancen von Fruehgeborenen enorm verbessert, aber auch viele Probleme und Fragen aufgeworfen. In dieser Arbeit wurde untersucht, ob Hyperoxie Einfluss nimmt auf die Expression von apoptotischen Genen, Wachstumsfaktoren und Zytokinen und so ueber verschiedene Mechanismen und Signalwege zu einem Ungleichgewicht der ueber das neuronale Ueberleben entscheidenden Faktoren fuehrt. 6-Tage alte Ratten wurden fuer bestimme Zeitabschnitte (2, 6, 12, 24, 48, 72 Stunden) einer 80%igen Sauerstoffkonzentration ausgesetzt. In dieser Arbeit konnte am unreifen Rattengehirn nachgewiesen werden, dass eine 80%ige Sauerstoffkonzentration in der Atemluft maximal nach 12 bis 24 Stunden zu einer ausgepraegten, diffusen apoptotischen Neurodegeneration im Gehirn fuehrt. Die Exposition mit hoher Sauerstoffkonzentration fuehrte im unreifen Gehirn zu einer deutlich verminderten Expression der Neurotrophinen, wie deren Signalproteine ERK 1/2 und Akt. Als spezifischer Nachweis fuer eine apoptotische Neurodegeneration wurden neben dem histologischen Verfahren auf molekularer Ebene apoptotische Gene untersucht. Unter Hyperoxie kam es zu einer erhoehten Expression des Todesrezeptors Fas und einer gesteigerten Aktivitaet von Caspase-3.Des Weiteren fand sich infolge der Hyperoxieexposition ein drastischer Anstieg der inflammatorischen Zytokine IL-1beta und IL-18. Es zeigt sich also, dass hohe Sauerstoffkonzentrationen in einer sehr vulnerablen Phase der Hirnentwicklung (Phase des rapiden Hirnwachstums) zu massiven Veraenderungen fuehren, welche den bisher ungeklaerten diffusen Neuronenuntergang bei Fruehgeborenen erklaeren koennten. Die vorliegenden Ergebnisse implizieren aeu§erste Vorsicht bei der therapeutischen Anwendung von Sauerstoff bei Fruehgeborenen, fuer die die postnatalen Konditionen, verglichen mit den intrauterinen Bedingungen, immer hyperoxisch sind und die noch ueber ein unreifes Antioxidationssystem verfuegen. / Infants born prematurely may develop neurocognitive deficits without an obvious cause. Oxygen, which is widely used in neonatal medicine, constitutes one possible contributing neurotoxic factor, because it can trigger neuronal apoptosis in the developing brain of rodents. Premature infants are exposed to partial oxygen pressures that are fourfold higher compared to intrauterine conditions, even if no supplemental oxygen is administered. Here is reported that short exposures to nonphysiologic oxygen levels can trigger apoptotic neurodegeneration in the developing brain. Vulnerability to oxygen neurotoxicity is confined to the first 2 weeks of life, a period characterized by rapid growth, which in humans expands from the sixth month of pregnancy to the third year of life. Hyperoxia caused decreased expression of neurotrophins, and inactivation of survival signalling proteins extracellular signal-regulated kinase (ERK1/2), and protein kinase B (Akt). In addition we hypothesized that two caspase-1-processed cytokines, interleukin (IL)-1beta and IL-18, are involved in oxygen-induced neuronal cell death. Six-day-old Wistar rats were exposed to 80% oxygen for various time periods (2, 6, 12, 24, 48, 72 hours). Neuronal cell death in the brain, as assessed by silver staining, peaked at 12 to 24 hours and was preceded by a marked increase in mRNA of IL-1beta, IL-18 and FAS and a decrease in mRNA and protein levels of neurotrophins and ERK1/2 and Akt Our findings reveal mechanisms that could potentially damage the developing brain of human premature neonates.

No description available.

INTRODUÇÃO: As doenças retinianas associadas à neovascularização, tais como a degeneração macular relacionada à idade e as retinopatias diabética e da prematuridade são as principais e mais importantes causas da cegueira em todo o mundo. Nos últimos anos, injeções intravítreas de fármacos com ação antiangiogênica, como o bevacizumabe (BVZ), têm sido de grande valia tanto em pacientes na fase adulta quanto nos recém-natos. Todavia, estudos experimentais in vitro e in vivo sugerem que essas drogas promovam efeitos adversos sobre alguns processos celulares, interferindo diretamente em mecanismos fisiológicos que mantém a homeostase do tecido retiniano, incluindo os mecanismos de proliferação, diferenciação e morte celular. OBJETIVO: investigar o efeito do BVZ nos processos de transcrição e tradução de marcadores da gliose: GFAP e vimentina, de morte celular, caspase-3 e beclina-1, e dos proteoglicanos relacionados à manutenção e desenvolvimento de tecido retiniano: neurocam, fosfacam e sindecam-3. MÉTODOS: Dois modelos experimentais foram usados nesse estudo: 1) linhagem celular de Müller de Glia humana adulta (MIO-M1), cultivada em meio de cultura D-MEM na presença e ausência de BVZ por 12 e 24 horas nas concentrações de 0,25 mg/mL e 0,50 mg/mL e 2) explantes de retinas de ratos 2 dias pós-nascidos submetidos à 0,50 mg/mL da droga por 48 horas. Durante este período foram mantidos a 5% de dióxido de carbono à temperatura de 37°C. A análise de proteínas foi realizada por imunocitohistoquímica e Western Blotting e a expressão de RNAm, pela reação em cadeia da polimerase em tempo real (PCR Real Time). Foi utilizado o Teste de ANOVA - fator único para a comparação entre os grupos controle e tratados com BVZ de um mesmo período (12h ou 24h) e o teste t de Student para a comparação entre as mesmas concentrações de 12h e 24h, e para a comparação entre os grupos controle e tratado com BVZ dos explantes (p < 0,05). RESULTADOS: Nas células MIO-M1, o BVZ, aumentou a expressão gênica e diminui a tradução de VEGF na concentração de 0,50 mg/mL em 24h comparado a 12h. Para o GFAP, houve um aumento da transcrição em 0,50 mg/mL em 24h comparado a 12h e aos outros grupos em 24h. Entretanto, houve diminuição da tradução para estes mesmos períodos e condições. Para a vimentina, houve aumento na transcrição em 0,50 mg/mL após 24h. Os achados de beclina-1 revelaram uma diminuição da transcrição e tradução em 0,25 mg/mL em 24h comparado a 12h. A transcrição entre os grupos do mesmo período aumentou nos grupos tratados com BVZ tanto em 12h quanto em 24h. A tradução da beclina-1 diminuiu em 0,25 mg/mL, mas aumentou em 0,50 mg/mL em 24h em relação à 12h. A comparação entre os grupos de 24h revelou aumento da tradução em 0,50 mg/mL. Para a caspase-3, houve diminuição da transcrição em 0,25 mg/mL e 0,50 mg/mL em 24h em relação a 12h e entre nos grupos tratados com BVZ em 24h. A tradução revelou um aumento em 0,50 mg/mL em 24h em relação a 12h. No fosfacam, houve diminuição da transcrição em 0,50 mg/mL em 24h comparado a 12h e entre os grupos tratados com BVZ e controles para 12h e 24h. A transcrição de neurocam diminuiu em 0,25 mg/mL e 0,50 mg/mL em 24h comparado a 12h e entre os grupos tratados com BVZ e controles em 12h e 24h. A tradução aumentou em 0,50 mg/mL em 24h em relação a 12h, mas diminuiu entre os grupos em 24h. Nos explantes, a transcrição e tradução de VEGF diminuiram no grupo tratado com BVZ após 48h. CONCLUSÃO: Nossos resultados relacionados às células MIO-M1 e ao explante de ratos, in vitro, nos permitem aventar o possível comprometimento ocasionado pela depleção do VEGF pelo BVZ na homeostase do tecido retiniano, in vivo, interferindo nas moléculas envolvidas na morte e diferenciação celular e na neuroproteção em indivíduos em fase adulta e recém-nato / Backgraound: Vasoproliferative retinal disorders such as age-related macular, degeneration, diabetic retinopathy and retinopathy of prematurity are major causes of blindness in the world. In recent years, intravitreal injections of drugs with antiangiogenic action, as bevacizumab, have been very useful for both patients in adulthood and in newborns. However, experimental studies, in vivo and in vitro, suggest that antiangiogenic drugs may promote side effects in cellular proceedings, interfering directly in physiological mechanisms of cellular proliferation, differentiation and death. POURPOSE: Investigate the bevacizumab effects in transcription and translation processes of gliosis, GFAP and vimentin, cellular death markers, caspase-3 and beclin-1, and proteoglycans involved in retinal tissue maintenance and development, neurocan, phosphacan and syndecan-3. METHODS: Two experimental models were used on this research: cellular lineage of adult and human Müller glial cell(MIO-M1) were cultivated on D-MEM medium with 0,25 and 0,50 mg/mL bevacizumab for 12 and 24 hours, and two days old rat retinal explants submitted to 0,50 mg/mL for 48 hours. During this period were stored in laboratory ovens at 5% carbon dioxide pressure and 37 °C average temperature. Molecular techniques were used to evaluate gene expression and protein content. Protein assessments were performed by immunocytochemistry and western blotting analysis, while Real Time PCR was used to measure mRNA content. ANOVA tests one factor were applied to compare the control and BVZ groups of the same period (12h or 24h) and t test from Student to compare the same conditions of 12h and 24h, and to compare the control and BVZ retinal explants groups (p<0.05). RESULTS: At MIO-M1 cells, BVZ increased the gene expression and reduced the translation of VEGF at concentration of 0.50 mg / mL in 24 hours compared to 12 hours. For GFAP, there was an increase of transcription at 0.50 mg / mL in 24 hours compared to 12 hours and to the other groups at 24 hours. However, there was a decrease in translation for these same periods and conditions. For vimentin, there was an increase in transcription at 0.50 mg / mL after 24 hours. The beclin-1 findings revealed a decrease of transcription and translation at 0.25 mg / ml compared at 24 h compared to 12h. Transcription among groups increased in BVZ treated groups at 12h and 24h. The translation of beclin-1 decreased at 0.25 mg / ml, but increased at 0.50 mg / mL at 24 hours compared to 12 hours. The comparison between the groups at 24h revealed an increased in translation at 0.50 mg / mL. For caspase-3, there was a decrease in transcription at 0.25 mg / ml and 0.50 mg / ml at 24 compared to 12 hours and among BVZ treated groups at 24h. Translation revealed an increase at 0.50 mg / mL at 24 hours compared to 12 hours. For fosfacam, there was a decreased in transcription at 0.50 mg / mL in 24 hours compared to 12 hours and among BVZ treated groups and controls at 12h and 24h. The transcription of neurocam decreased at 0.25 mg / ml and 0.50 mg / ml at 24 hours compared to 12 hours and among BVZ treated groups and controls at 12h and 24h. Translation increased at 0.50 mg / mL at 24 compared to 12 hours, but decreased among the groups at 24 hours. For explants, transcription and translation of VEGF decreased in the BVZ group treated after 48h. CONCLUSION: Our results related to the MIO-M1 cells and explants of rats,in vitro, allow us to suggest the possible impairment caused by depletion of VEGF by BVZ in the homeostasis of retinal tissue, in vivo, interfering in the molecules involved in cell death and cell differentiation and neuroprotection in individuals in adulthood and newborns

Ces dernières années, de nombreuses études ont prouvé que la protéine précurseur de l'amyloïde (APP) joue un rôle clé dans le processus de formation de la mémoire, le développement des connexions synaptiques et la régulation de la force synaptique. L’importance d’APP naît du fait que son clivage protéolytique produit le peptide bêta-amyloïde (Aβ), considéré comme l'un des facteurs cruciaux dans le développement de la maladie d'Alzheimer. Les recherches se sont donc concentrées sur Aβ plutôt que sur le domaine intracellulaire APP (APP-ICD). Récemment, il a été démontré qu’APP-ICD affecte l'induction de la plasticité synaptique, et Aβ à haute concentration est connu pour induire une dépression synaptique. Ici, nous montrons qu’APP-ICD et Aβ fonctionnent ensemble et induisent une dépression synaptique en modifiant la transmission synaptique par effet additif. L’activation de la caspase-3 clivant APP-ICD est nécessaire pour la dépression à long terme. Nous constatons que l’activation de la caspase-3 et son site de clivage d’APP-ICD, ainsi que le clivage d’APP par la gamma-sécrétase sont nécessaires à la dépression synaptique dépendante d’Aβ. La microglie assure la clairance d’Aβ et certains effets de plasticité. Nous démontrons qu’elle médie partiellement la dépression synaptique dépendante d’Aβ. Les mécanismes par lesquels APP-ICD et Aβ médient la dépression synaptique ne sont pas connus. Ici, nous discutons de pistes possibles pour la recherche future, notamment des changements dans l'homéostasie du calcium en tant que cible thérapeutique potentielle. Comprendre comment APP-ICD et Aβ travaillent ensemble pour induire une dépression synaptique aiderait à développer de meilleurs traitements pour la maladie d'Alzheimer. / In recent years, more and more evidence has proven that the amyloid precursor protein (APP) plays a key role in the process of memory formation, the development of synaptic connections, and the regulation of synaptic strength. APP rose to prominence since its proteolytic cleavage produces the amyloid-beta (Aβ) peptide, which is believed to be one of the crucial factors in the development of Alzheimer disease. Therefore, most of the research focused on Aβ, while APP intracellular domain (APP-ICD) received much less attention. In a recent study, APP-ICD was shown to affect the induction of synaptic plasticity, and Aβ at high concentration is known to induce synaptic depression. Here we show that APP-ICD works together with Aβ to induce synaptic depression, meaning they have an additive effect that changes synaptic transmission. Caspase-3 cleaves APP-ICD, and its activation is required for long-term depression. We found that the caspase-3 cleavage site of APP-ICD and caspase-3 activation are needed for Aβ-dependent synaptic depression. We also show that cleavage of APP by gamma-secretase is needed for the effect. Microglia mediate clearance of Aβ as well as some plasticity effects. We demonstrate that microglia partially mediate Aβ-dependent synaptic depression. The mechanisms of how APP-ICD and Aβ mediate synaptic depression are not known, here, we discuss possible avenues for future research, specifically changes in calcium homeostasis as a potential therapeutic target. Hence, understanding how APP-ICD and Aβ work together to induce synaptic depression would aid in developing better treatments for Alzheimer disease.

<p>Women with pregestational diabetes have a 2-5 fold increased risk of giving birth to malformed babies compared with non-diabetic women. Diabetes-induced oxidative stress in maternal and embryonic tissues has been implicated in the teratogenic process. The malformations are likely to be induced before the seventh week of pregnancy, when the yolk sac is partly responsible for the transfer of metabolites to the embryo, and the uterine blood flow to the implantation site determines the net amount of nutrients available to the conceptus. We aimed to evaluate the effect on embryogenesis caused by a diabetes-induced disturbance in yolk sac morphology, uterine blood flow or altered maternal antioxidative status in conjunction with a varied severity of the maternal diabetic state.</p><p>We investigated to which extent maternal diabetes with or without folic acid (FA) supplementation affects mRNA levels and protein distribution of ROS scavenging enzymes (SOD, CAT, GPX), vascular endothelial growth factor-A (Vegf-A), folate binding protein-1 (Folbp-1), and apoptosis associated proteins (Bax, Bcl-2, Caspase-3) in the yolk sacs of rat embryos on gestational days 10 and 11. We found that maternal diabetes impairs, and that FA supplementation restores, yolk sac vessel morphology, and that maternal diabetes is associated with increased apoptotic rate in embryos and yolk sacs, as well as impaired SOD gene expression. We assessed uterine blood flow with a laser-Doppler-flow-meter and found increased blood flow to implantation sites of diabetic rats compared with controls. Furthermore, resorbed and malformed offspring showed increased and decreased blood flow to their implantation sites, respectively. In mice with genetically altered CuZnSOD levels, maternal diabetes increased embryonic dysmorphogenesis irrespective of CuZnSOD expression. We thus found the maternal diabetic state to be a major determinant of diabetic embryopathy and that the CuZnSOD status exerts a partial protection for the embryo in diabetic pregnancy. </p>