28 research outputs found
Caractérisation des mécanismes de la traduction dans les astrocytes
Dans le systĂšme nerveux central, les astrocytes, cellules gliales, jouent des rĂŽles cruciaux dans la physiologie du cerveau en rĂ©gulant la transmission synaptique, lâhomĂ©ostasie ionique, lâintĂ©gritĂ© de la barriĂšre sang-cerveau et le flux sanguin cĂ©rĂ©bral. Ces fonctions sont soutenues par des polaritĂ©s morphologique et molĂ©culaire des astrocytes avec des interfaces contactant les synapses, avec les prolongements pĂ©risynaptiques (PAP), et les vaisseaux sanguins, avec les prolongements pĂ©rivasculaires (PvAP). Nous et dâautres avons dĂ©montrĂ© la prĂ©sence dâARNm, de ribosomes et de synthĂšse protĂ©ique locale dans les PAPs et PvAPs et proposĂ© que la traduction locale soit un mĂ©canisme pour la mise en place de la polaritĂ© astrocytaire. Cependant, on connaĂźt peu les mĂ©canismes de traduction dans les astrocytes. Mon projet de thĂšse a eu pour but de dĂ©crypter comment la traduction dans les astrocytes est rĂ©gulĂ©e et le quels sont les rĂŽles de ces mĂ©canismes dans la physiologie du cerveau. Nous avons dâabord caractĂ©risĂ© la distribution des ARNm dans les astrocytes en dĂ©veloppant AstroDot, une approche in situ pour quantifier la densitĂ© et la distribution des ARNm. Nous avons dĂ©terminĂ© dans les astrocytes de lâhippocampe que la distribution et la densitĂ© dâARNm codant pour les isoformes alpha et delta de la GFAP Ă©taient altĂ©rĂ©es et variaient avec la prĂ©sence de plaques amyloĂŻdes dans un modĂšle murin de la maladie dâAlzheimer. Nous avons aussi montrĂ© pour la 1Ăšre fois la prĂ©sence dâARNm dans les prolongements de microglies, une cellule gliale impliquĂ©e dans lâimmunitĂ© cĂ©rĂ©brale. AprĂšs, jâai voulu identifier les mĂ©canismes de mise en place de la traduction dans les astrocytes et je me suis concentrĂ© sur les protĂ©ines associĂ©es aux polysomes de cette cellule. Jâai dĂ©veloppĂ© une mĂ©thode combinant le TRAP avec la spectromĂ©trie de masse. Parmi les protĂ©ines immunoprĂ©cipitĂ©es, je me suis concentrĂ© sur RACK1, une protĂ©ine dâĂ©chafaudage connue pour sâassocier avec la petite sous unitĂ© des ribosomes. Notre analyse prĂ©cĂ©dente du translatome des PAPs a identifiĂ© Gnb2l1, codant pour RACK1, comme lâun des ARNm traduit les plus enrichis dans les PAPs suggĂ©rant son rĂŽle dans la rĂ©gulation de la traduction Ă cette interface. RACK1 agit comme un rĂ©gulateur de la formation des ribosomes, de la traduction et prend part au contrĂŽle qualitĂ© des ARNm. Son rĂŽle dans les astrocytes Ă©tait inconnu. En utilisant un panel restreint dâARN astrocytaires spĂ©cifiques, jâai montrĂ© que RACK1 Ă©tait prĂ©fĂ©rentiellement associĂ© Ă Kcnj10 codant pour le canal potassique KIR4.1 et Slc1a2 codant pour le transporteur au glutamate GLT1. Pour adresser le rĂŽle de RACK1 dans les astrocytes, jâai dĂ©veloppĂ© un modĂšle de souris dans laquelle RACK1 est inactivĂ© dans les astrocytes. Dans ce modĂšle, le niveau de KIR4.1 Ă©tait augmentĂ© dans le cerveau et dans les PAPs alors que GLT1 Ă©tait inchangĂ©. RACK1 peut agir aux niveaux du ribosome et de lâARN pour rĂ©guler la traduction. Des expĂ©riences in vitro sur des cellules HEK RACK1 KO transfectĂ©es avec des rapporteurs lucifĂ©rase ont montrĂ© que lâaugmentation de KIR4.1 nâimpliquait pas le blocage des ribosomes sur la sĂ©quence codante de son ARNm kcnj10 mais Ă©tait liĂ© Ă sa partie 5â non codante. Nous avons adressĂ© les consĂ©quences physiologiques de ces rĂ©gulations. Par enregistrements Ă©lectrophysiologiques, nous avons dĂ©terminĂ© que lâaugmentation de KIR4.1 en lâabsence de RACK1 menait Ă un changement dans les propriĂ©tĂ©s Ă©lectriques des neurones de lâhippocampe avec une protection globale contre des activitĂ©s synaptiques Ă©levĂ©es certainement due Ă une plus grande capacitĂ© des PAPs Ă capturer le potassium. En rĂ©sumĂ©, jâai dĂ©veloppĂ© une nouvelle mĂ©thode pour caractĂ©riser la distribution des ARNm dans les astrocytes. Jâai identifiĂ© un pool de protĂ©ines associĂ©es aux polyribosomes astrocytaires. Enfin, Je me suis concentrĂ© sur RACK1 et je lâai identifiĂ© comme un rĂ©gulateur de la traduction de KIR4.1 et de lâhomĂ©ostasie du potassium pĂ©risynaptique.In the central nervous system, astrocytes are glial cells displaying crucial roles in the brain physiology by regulating synaptic transmission, ion homeostasis, the blood brain barrier integrity or the cerebral blood flow. These functions are sustained by morphological and molecular polarities of astrocytes with specific interfaces contacting synapses, the perisynaptic processes (PAP), and blood vessels, the perivascular processes (PvAP). Recently, my laboratory and others demonstrated the presence of mRNAs, ribosomes and local protein synthesis in PAPs and PvAPs and proposed local translation as a mechanism for setting astrocytic polarity. However, little is known about the mechanisms of translation in astrocytes. My PhD project aimed at deciphering how translation is regulated in astrocytes and their interfaces and the role of these mechanisms in brain physiology. First, to characterize the distribution of mRNAs in astrocytes, I developed AstroDot, a specific in-situ approach to quantify the density and distribution of mRNAs in astrocytes. I determined that in hippocampal astrocytes, the distribution and density of mRNAs encoding α and ÎŽ isoforms of the glial fibrillary acidic protein (GFAP) are altered and vary with the presence of amyloid plaques in APP/PS1dE9 mice, a mouse model of Alzheimerâs disease. I also demonstrated for the first time the presence of mRNAs in microglia processes, a resident glial cell involved in particular in brain immunity. Following this study, I aimed at identifying mechanisms setting translation in astrocytes and focused on proteins associated with polysomes in astrocytes. I developed a method combining translating ribosome affinity purification in astrocytes with mass spectrometry. Among immunoprecipitated proteins, I focused on RACK1, a scaffold protein known to associate with the small subunit of ribosomes. Our previous analysis of the translatome in PAPs identified Gnb2l1 encoding RACK1 as one of the most enriched translated mRNAs in PAPs, suggesting its possible role in the regulation of translation at this interface. RACK1 acts as a ribosome formation mediator, a translation regulator and takes part in RNA quality control. Its role in astrocytes was unknown. Using a restricted panel of astrocytic enriched or specific mRNAs, I showed that RACK1 preferentially associates with Kncj10 coding for the potassium channel KIR4.1, one of the main regulator of K+ homeostasis in PAPs and PvAPs, and Slc1a2 coding for a glutamate transporter GLT1 which allows glutamate recycling in PAPs. To further address the role of RACK1 in astrocytes, I developed a mouse model in which RACK1 is specifically inactivated in astrocytes (RACK1 cKO). In this model, I found the level of KIR4.1 upregulated in the brain and in PAPs, whereas GLT1 was unchanged. RACK1 can act on the ribosome and on the RNA levels to regulate translation. In vitro investigations on RACK1 KO HEK cells transfected with luciferase reporters showed that KIR4.1 upregulation does not involve ribosome stalling on the Kncj10 coding sequence but relies on a part of the 5âUTR of Kcnj10 (Collaboration with ClĂ©ment Chapat, Polytechnique). We finally addressed the physiological consequences of these regulations. Performing electrophysiological recordings (Collaboration with Nathalie Rouach, CIRB), we determined that KIR4.1 increase in absence of RACK1 leads to changes in the electrophysiological properties of the hippocampal neurons with an overall protection against high synaptic activity, certainly due to a higher capacity of PAPs to uptake K+. In summary, I developed during my thesis a new method to characterize mRNA distribution in astrocytes. I identified a pool of proteins associated to polysomes in astrocytes. Finally, I focused on RACK1 and identified it as an important regulator of KIR4.1 translation and astrocytic perisynaptic K+ homeostasis
Caractérisation des mécanismes de la traduction dans les astrocytes
In the central nervous system, astrocytes are glial cells displaying crucial roles in the brain physiology by regulating synaptic transmission, ion homeostasis, the blood brain barrier integrity or the cerebral blood flow. These functions are sustained by morphological and molecular polarities of astrocytes with specific interfaces contacting synapses, the perisynaptic processes (PAP), and blood vessels, the perivascular processes (PvAP). Recently, my laboratory and others demonstrated the presence of mRNAs, ribosomes and local protein synthesis in PAPs and PvAPs and proposed local translation as a mechanism for setting astrocytic polarity. However, little is known about the mechanisms of translation in astrocytes. My PhD project aimed at deciphering how translation is regulated in astrocytes and their interfaces and the role of these mechanisms in brain physiology. First, to characterize the distribution of mRNAs in astrocytes, I developed AstroDot, a specific in-situ approach to quantify the density and distribution of mRNAs in astrocytes. I determined that in hippocampal astrocytes, the distribution and density of mRNAs encoding α and ÎŽ isoforms of the glial fibrillary acidic protein (GFAP) are altered and vary with the presence of amyloid plaques in APP/PS1dE9 mice, a mouse model of Alzheimerâs disease. I also demonstrated for the first time the presence of mRNAs in microglia processes, a resident glial cell involved in particular in brain immunity. Following this study, I aimed at identifying mechanisms setting translation in astrocytes and focused on proteins associated with polysomes in astrocytes. I developed a method combining translating ribosome affinity purification in astrocytes with mass spectrometry. Among immunoprecipitated proteins, I focused on RACK1, a scaffold protein known to associate with the small subunit of ribosomes. Our previous analysis of the translatome in PAPs identified Gnb2l1 encoding RACK1 as one of the most enriched translated mRNAs in PAPs, suggesting its possible role in the regulation of translation at this interface. RACK1 acts as a ribosome formation mediator, a translation regulator and takes part in RNA quality control. Its role in astrocytes was unknown. Using a restricted panel of astrocytic enriched or specific mRNAs, I showed that RACK1 preferentially associates with Kncj10 coding for the potassium channel KIR4.1, one of the main regulator of K+ homeostasis in PAPs and PvAPs, and Slc1a2 coding for a glutamate transporter GLT1 which allows glutamate recycling in PAPs. To further address the role of RACK1 in astrocytes, I developed a mouse model in which RACK1 is specifically inactivated in astrocytes (RACK1 cKO). In this model, I found the level of KIR4.1 upregulated in the brain and in PAPs, whereas GLT1 was unchanged. RACK1 can act on the ribosome and on the RNA levels to regulate translation. In vitro investigations on RACK1 KO HEK cells transfected with luciferase reporters showed that KIR4.1 upregulation does not involve ribosome stalling on the Kncj10 coding sequence but relies on a part of the 5âUTR of Kcnj10 (Collaboration with ClĂ©ment Chapat, Polytechnique). We finally addressed the physiological consequences of these regulations. Performing electrophysiological recordings (Collaboration with Nathalie Rouach, CIRB), we determined that KIR4.1 increase in absence of RACK1 leads to changes in the electrophysiological properties of the hippocampal neurons with an overall protection against high synaptic activity, certainly due to a higher capacity of PAPs to uptake K+. In summary, I developed during my thesis a new method to characterize mRNA distribution in astrocytes. I identified a pool of proteins associated to polysomes in astrocytes. Finally, I focused on RACK1 and identified it as an important regulator of KIR4.1 translation and astrocytic perisynaptic K+ homeostasis.Dans le systĂšme nerveux central, les astrocytes, cellules gliales, jouent des rĂŽles cruciaux dans la physiologie du cerveau en rĂ©gulant la transmission synaptique, lâhomĂ©ostasie ionique, lâintĂ©gritĂ© de la barriĂšre sang-cerveau et le flux sanguin cĂ©rĂ©bral. Ces fonctions sont soutenues par des polaritĂ©s morphologique et molĂ©culaire des astrocytes avec des interfaces contactant les synapses, avec les prolongements pĂ©risynaptiques (PAP), et les vaisseaux sanguins, avec les prolongements pĂ©rivasculaires (PvAP). Nous et dâautres avons dĂ©montrĂ© la prĂ©sence dâARNm, de ribosomes et de synthĂšse protĂ©ique locale dans les PAPs et PvAPs et proposĂ© que la traduction locale soit un mĂ©canisme pour la mise en place de la polaritĂ© astrocytaire. Cependant, on connaĂźt peu les mĂ©canismes de traduction dans les astrocytes. Mon projet de thĂšse a eu pour but de dĂ©crypter comment la traduction dans les astrocytes est rĂ©gulĂ©e et le quels sont les rĂŽles de ces mĂ©canismes dans la physiologie du cerveau. Nous avons dâabord caractĂ©risĂ© la distribution des ARNm dans les astrocytes en dĂ©veloppant AstroDot, une approche in situ pour quantifier la densitĂ© et la distribution des ARNm. Nous avons dĂ©terminĂ© dans les astrocytes de lâhippocampe que la distribution et la densitĂ© dâARNm codant pour les isoformes alpha et delta de la GFAP Ă©taient altĂ©rĂ©es et variaient avec la prĂ©sence de plaques amyloĂŻdes dans un modĂšle murin de la maladie dâAlzheimer. Nous avons aussi montrĂ© pour la 1Ăšre fois la prĂ©sence dâARNm dans les prolongements de microglies, une cellule gliale impliquĂ©e dans lâimmunitĂ© cĂ©rĂ©brale. AprĂšs, jâai voulu identifier les mĂ©canismes de mise en place de la traduction dans les astrocytes et je me suis concentrĂ© sur les protĂ©ines associĂ©es aux polysomes de cette cellule. Jâai dĂ©veloppĂ© une mĂ©thode combinant le TRAP avec la spectromĂ©trie de masse. Parmi les protĂ©ines immunoprĂ©cipitĂ©es, je me suis concentrĂ© sur RACK1, une protĂ©ine dâĂ©chafaudage connue pour sâassocier avec la petite sous unitĂ© des ribosomes. Notre analyse prĂ©cĂ©dente du translatome des PAPs a identifiĂ© Gnb2l1, codant pour RACK1, comme lâun des ARNm traduit les plus enrichis dans les PAPs suggĂ©rant son rĂŽle dans la rĂ©gulation de la traduction Ă cette interface. RACK1 agit comme un rĂ©gulateur de la formation des ribosomes, de la traduction et prend part au contrĂŽle qualitĂ© des ARNm. Son rĂŽle dans les astrocytes Ă©tait inconnu. En utilisant un panel restreint dâARN astrocytaires spĂ©cifiques, jâai montrĂ© que RACK1 Ă©tait prĂ©fĂ©rentiellement associĂ© Ă Kcnj10 codant pour le canal potassique KIR4.1 et Slc1a2 codant pour le transporteur au glutamate GLT1. Pour adresser le rĂŽle de RACK1 dans les astrocytes, jâai dĂ©veloppĂ© un modĂšle de souris dans laquelle RACK1 est inactivĂ© dans les astrocytes. Dans ce modĂšle, le niveau de KIR4.1 Ă©tait augmentĂ© dans le cerveau et dans les PAPs alors que GLT1 Ă©tait inchangĂ©. RACK1 peut agir aux niveaux du ribosome et de lâARN pour rĂ©guler la traduction. Des expĂ©riences in vitro sur des cellules HEK RACK1 KO transfectĂ©es avec des rapporteurs lucifĂ©rase ont montrĂ© que lâaugmentation de KIR4.1 nâimpliquait pas le blocage des ribosomes sur la sĂ©quence codante de son ARNm kcnj10 mais Ă©tait liĂ© Ă sa partie 5â non codante. Nous avons adressĂ© les consĂ©quences physiologiques de ces rĂ©gulations. Par enregistrements Ă©lectrophysiologiques, nous avons dĂ©terminĂ© que lâaugmentation de KIR4.1 en lâabsence de RACK1 menait Ă un changement dans les propriĂ©tĂ©s Ă©lectriques des neurones de lâhippocampe avec une protection globale contre des activitĂ©s synaptiques Ă©levĂ©es certainement due Ă une plus grande capacitĂ© des PAPs Ă capturer le potassium. En rĂ©sumĂ©, jâai dĂ©veloppĂ© une nouvelle mĂ©thode pour caractĂ©riser la distribution des ARNm dans les astrocytes. Jâai identifiĂ© un pool de protĂ©ines associĂ©es aux polyribosomes astrocytaires. Enfin, Je me suis concentrĂ© sur RACK1 et je lâai identifiĂ© comme un rĂ©gulateur de la traduction de KIR4.1 et de lâhomĂ©ostasie du potassium pĂ©risynaptique
Caractérisation des mécanismes de la traduction dans les astrocytes
In the central nervous system, astrocytes are glial cells displaying crucial roles in the brain physiology by regulating synaptic transmission, ion homeostasis, the blood brain barrier integrity or the cerebral blood flow. These functions are sustained by morphological and molecular polarities of astrocytes with specific interfaces contacting synapses, the perisynaptic processes (PAP), and blood vessels, the perivascular processes (PvAP). Recently, my laboratory and others demonstrated the presence of mRNAs, ribosomes and local protein synthesis in PAPs and PvAPs and proposed local translation as a mechanism for setting astrocytic polarity. However, little is known about the mechanisms of translation in astrocytes. My PhD project aimed at deciphering how translation is regulated in astrocytes and their interfaces and the role of these mechanisms in brain physiology. First, to characterize the distribution of mRNAs in astrocytes, I developed AstroDot, a specific in-situ approach to quantify the density and distribution of mRNAs in astrocytes. I determined that in hippocampal astrocytes, the distribution and density of mRNAs encoding α and ÎŽ isoforms of the glial fibrillary acidic protein (GFAP) are altered and vary with the presence of amyloid plaques in APP/PS1dE9 mice, a mouse model of Alzheimerâs disease. I also demonstrated for the first time the presence of mRNAs in microglia processes, a resident glial cell involved in particular in brain immunity. Following this study, I aimed at identifying mechanisms setting translation in astrocytes and focused on proteins associated with polysomes in astrocytes. I developed a method combining translating ribosome affinity purification in astrocytes with mass spectrometry. Among immunoprecipitated proteins, I focused on RACK1, a scaffold protein known to associate with the small subunit of ribosomes. Our previous analysis of the translatome in PAPs identified Gnb2l1 encoding RACK1 as one of the most enriched translated mRNAs in PAPs, suggesting its possible role in the regulation of translation at this interface. RACK1 acts as a ribosome formation mediator, a translation regulator and takes part in RNA quality control. Its role in astrocytes was unknown. Using a restricted panel of astrocytic enriched or specific mRNAs, I showed that RACK1 preferentially associates with Kncj10 coding for the potassium channel KIR4.1, one of the main regulator of K+ homeostasis in PAPs and PvAPs, and Slc1a2 coding for a glutamate transporter GLT1 which allows glutamate recycling in PAPs. To further address the role of RACK1 in astrocytes, I developed a mouse model in which RACK1 is specifically inactivated in astrocytes (RACK1 cKO). In this model, I found the level of KIR4.1 upregulated in the brain and in PAPs, whereas GLT1 was unchanged. RACK1 can act on the ribosome and on the RNA levels to regulate translation. In vitro investigations on RACK1 KO HEK cells transfected with luciferase reporters showed that KIR4.1 upregulation does not involve ribosome stalling on the Kncj10 coding sequence but relies on a part of the 5âUTR of Kcnj10 (Collaboration with ClĂ©ment Chapat, Polytechnique). We finally addressed the physiological consequences of these regulations. Performing electrophysiological recordings (Collaboration with Nathalie Rouach, CIRB), we determined that KIR4.1 increase in absence of RACK1 leads to changes in the electrophysiological properties of the hippocampal neurons with an overall protection against high synaptic activity, certainly due to a higher capacity of PAPs to uptake K+. In summary, I developed during my thesis a new method to characterize mRNA distribution in astrocytes. I identified a pool of proteins associated to polysomes in astrocytes. Finally, I focused on RACK1 and identified it as an important regulator of KIR4.1 translation and astrocytic perisynaptic K+ homeostasis.Dans le systĂšme nerveux central, les astrocytes, cellules gliales, jouent des rĂŽles cruciaux dans la physiologie du cerveau en rĂ©gulant la transmission synaptique, lâhomĂ©ostasie ionique, lâintĂ©gritĂ© de la barriĂšre sang-cerveau et le flux sanguin cĂ©rĂ©bral. Ces fonctions sont soutenues par des polaritĂ©s morphologique et molĂ©culaire des astrocytes avec des interfaces contactant les synapses, avec les prolongements pĂ©risynaptiques (PAP), et les vaisseaux sanguins, avec les prolongements pĂ©rivasculaires (PvAP). Nous et dâautres avons dĂ©montrĂ© la prĂ©sence dâARNm, de ribosomes et de synthĂšse protĂ©ique locale dans les PAPs et PvAPs et proposĂ© que la traduction locale soit un mĂ©canisme pour la mise en place de la polaritĂ© astrocytaire. Cependant, on connaĂźt peu les mĂ©canismes de traduction dans les astrocytes. Mon projet de thĂšse a eu pour but de dĂ©crypter comment la traduction dans les astrocytes est rĂ©gulĂ©e et le quels sont les rĂŽles de ces mĂ©canismes dans la physiologie du cerveau. Nous avons dâabord caractĂ©risĂ© la distribution des ARNm dans les astrocytes en dĂ©veloppant AstroDot, une approche in situ pour quantifier la densitĂ© et la distribution des ARNm. Nous avons dĂ©terminĂ© dans les astrocytes de lâhippocampe que la distribution et la densitĂ© dâARNm codant pour les isoformes alpha et delta de la GFAP Ă©taient altĂ©rĂ©es et variaient avec la prĂ©sence de plaques amyloĂŻdes dans un modĂšle murin de la maladie dâAlzheimer. Nous avons aussi montrĂ© pour la 1Ăšre fois la prĂ©sence dâARNm dans les prolongements de microglies, une cellule gliale impliquĂ©e dans lâimmunitĂ© cĂ©rĂ©brale. AprĂšs, jâai voulu identifier les mĂ©canismes de mise en place de la traduction dans les astrocytes et je me suis concentrĂ© sur les protĂ©ines associĂ©es aux polysomes de cette cellule. Jâai dĂ©veloppĂ© une mĂ©thode combinant le TRAP avec la spectromĂ©trie de masse. Parmi les protĂ©ines immunoprĂ©cipitĂ©es, je me suis concentrĂ© sur RACK1, une protĂ©ine dâĂ©chafaudage connue pour sâassocier avec la petite sous unitĂ© des ribosomes. Notre analyse prĂ©cĂ©dente du translatome des PAPs a identifiĂ© Gnb2l1, codant pour RACK1, comme lâun des ARNm traduit les plus enrichis dans les PAPs suggĂ©rant son rĂŽle dans la rĂ©gulation de la traduction Ă cette interface. RACK1 agit comme un rĂ©gulateur de la formation des ribosomes, de la traduction et prend part au contrĂŽle qualitĂ© des ARNm. Son rĂŽle dans les astrocytes Ă©tait inconnu. En utilisant un panel restreint dâARN astrocytaires spĂ©cifiques, jâai montrĂ© que RACK1 Ă©tait prĂ©fĂ©rentiellement associĂ© Ă Kcnj10 codant pour le canal potassique KIR4.1 et Slc1a2 codant pour le transporteur au glutamate GLT1. Pour adresser le rĂŽle de RACK1 dans les astrocytes, jâai dĂ©veloppĂ© un modĂšle de souris dans laquelle RACK1 est inactivĂ© dans les astrocytes. Dans ce modĂšle, le niveau de KIR4.1 Ă©tait augmentĂ© dans le cerveau et dans les PAPs alors que GLT1 Ă©tait inchangĂ©. RACK1 peut agir aux niveaux du ribosome et de lâARN pour rĂ©guler la traduction. Des expĂ©riences in vitro sur des cellules HEK RACK1 KO transfectĂ©es avec des rapporteurs lucifĂ©rase ont montrĂ© que lâaugmentation de KIR4.1 nâimpliquait pas le blocage des ribosomes sur la sĂ©quence codante de son ARNm kcnj10 mais Ă©tait liĂ© Ă sa partie 5â non codante. Nous avons adressĂ© les consĂ©quences physiologiques de ces rĂ©gulations. Par enregistrements Ă©lectrophysiologiques, nous avons dĂ©terminĂ© que lâaugmentation de KIR4.1 en lâabsence de RACK1 menait Ă un changement dans les propriĂ©tĂ©s Ă©lectriques des neurones de lâhippocampe avec une protection globale contre des activitĂ©s synaptiques Ă©levĂ©es certainement due Ă une plus grande capacitĂ© des PAPs Ă capturer le potassium. En rĂ©sumĂ©, jâai dĂ©veloppĂ© une nouvelle mĂ©thode pour caractĂ©riser la distribution des ARNm dans les astrocytes. Jâai identifiĂ© un pool de protĂ©ines associĂ©es aux polyribosomes astrocytaires. Enfin, Je me suis concentrĂ© sur RACK1 et je lâai identifiĂ© comme un rĂ©gulateur de la traduction de KIR4.1 et de lâhomĂ©ostasie du potassium pĂ©risynaptique
[Ni(xbsms)Ru(CO)2Cl2]: A bioinspired nickel-ruthenium functional model of [NiFe] hydrogenase
International audienc
Dinuclear Nickel-Ruthenium Complexes as Functional Bio-Inspired Models of [NiFe] Hydrogenase
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Synthesis, crystal structure, magnetic properties and reactivity of a Ni-Ru model of NiFe hydrogenases with a pentacoordinated triplet (S=1) NiII center
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A structural and functional mimic of the active site of NiFe hydrogenases.
International audienceThe structural mimic of the active site of NiFe hydrogenases, [Ni(xbsms)FeCp(CO)](BF(4)), is an electrocatalyst for hydrogen evolution from trifluoroacetic acid in DMF
AstroDot -a new method for studying the spatial distribution of mRNA in astrocytes
International audienceAstrocytes are morphologically complex and use local translation to regulate distal functions. To study the distribution of mRNA in astrocytes, we combined mRNA detection via in situ hybridization with immunostaining of the astrocyte-specific intermediate filament glial fibrillary acidic protein (GFAP). mRNAs at the level of GFAP-immunolabelled astrocyte somata, and large and fine processes were analysed using AstroDot, an ImageJ plug-in and the R package AstroStat. Taking the characterization of mRNAs encoding GFAP-α and GFAP-Ύ isoforms as a proof of concept, we showed that they mainly localized on GFAP processes. In the APPswe/PS1dE9 mouse model of Alzheimer's disease, the density and distribution of both α and Ύ forms of Gfap mRNA changed as a function of the region of the hippocampus and the astrocyte's proximity to amyloid plaques. To validate our method, we confirmed that the ubiquitous Rpl4 (large subunit ribosomal protein 4) mRNA was present in astrocyte processes as well as in microglia processes immunolabelled for ionized calcium binding adaptor molecule 1 (Iba1; also known as IAF1). In summary, this novel set of tools allows the characterization of mRNA distribution in astrocytes and microglia in physiological or pathological settings
Tricarbonylmanganese(I)-lysozyme complex : a structurally characterized organometallic protein
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