90 research outputs found
Catalytic asymmetric synthesis of the alkaloid (+)-myrtine
A new protocol for the asymmetric synthesis of trans-2,6-disubstituted-4-piperidones has been developed using a catalytic enantioselective conjugate addition reaction in combination with a diastereoselective lithiationâsubstitution sequence; an efficient synthesis of (+)-myrtine has been achieved via this route.
Poly(ADP-ribose)-dependent chromatin unfolding facilitates the association of DNA-binding proteins with DNA at sites of damage
Zinc finger protein ZNF384 is an adaptor of Ku to DNA during classical non-homologous end-joining
Classical non-homologous end-joining (cNHEJ) is the dominant pathway used by human cells to repair DNA double-strand breaks (DSBs) and maintain genome stability. Here the authors show that PARP1-driven chromatin expansion allows the recruitment of ZNF384, which in turn recruits Ku70/Ku80 to facilitate cNHEJ.DNA double-strand breaks (DSBs) are among the most deleterious types of DNA damage as they can lead to mutations and chromosomal rearrangements, which underlie cancer development. Classical non-homologous end-joining (cNHEJ) is the dominant pathway for DSB repair in human cells, involving the DNA-binding proteins XRCC6 (Ku70) and XRCC5 (Ku80). Other DNA-binding proteins such as Zinc Finger (ZnF) domain-containing proteins have also been implicated in DNA repair, but their role in cNHEJ remained elusive. Here we show that ZNF384, a member of the C2H2 family of ZnF proteins, binds DNA ends in vitro and is recruited to DSBs in vivo. ZNF384 recruitment requires the poly(ADP-ribosyl) polymerase 1 (PARP1)-dependent expansion of damaged chromatin, followed by binding of its C2H2 motifs to the exposed DNA. Moreover, ZNF384 interacts with Ku70/Ku80 via its N-terminus, thereby promoting Ku70/Ku80 assembly and the accrual of downstream cNHEJ factors, including APLF and XRCC4/LIG4, for efficient repair at DSBs. Altogether, our data suggest that ZNF384 acts as a 'Ku-adaptor' that binds damaged DNA and Ku70/Ku80 to facilitate the build-up of a cNHEJ repairosome, highlighting a role for ZNF384 in DSB repair and genome maintenance.Cancer Signaling networks and Molecular Therapeutic
Rh-Catalyzed Asymmetric Hydrogenation of Prochiral Olefins with a Dynamic Library of Chiral TROPOS Phosphorus Ligands
ChemInform Abstract: Copper-Catalyzed Asymmetric Conjugate Addition of Trialkylaluminum Reagents to Trisubstituted Enones: Construction of Chiral Quaternary Centers.
Copper-catalyzed asymmetric conjugate addition to various Michael acceptors : construction of all-carbon quarternary chiral centres
L'emploi des ligands de type phosphoramidite pour l'Addition ConjuguĂ©e AsymĂ©trique (A.C.A.) catalysĂ©e par le cuivre d'espĂšces organozinciques (RâZn) ou organoaluminiques (RâAI) sur des substrats disubstituĂ©s, cycliques ou acycliques, de gĂ©omĂ©trie exclusivement E ou Z, conduit Ă la formation d'adduits chiraux avec d'excellentes Ă©nantiosĂ©lectivitĂ©s atteignant 99%. En outre, le caractĂšre acide de Lewis de RâAI permet une activation suffisante des substrats 2- ou 3-trisubstituĂ©s, et ainsi, l'obtention d'adduits cycliques possĂ©dant un centre quaternaire chiral avec une induction asymĂ©trique atteignant 98% via l'A.C.A. catalysĂ©e par le cuivre. L'utilisation des Ă©nolates mĂ©talliques Ă©nantio-enrichis est Ă©tudiĂ©e aussi bien pour les systĂšmes di- que trisubstituĂ©s, avec notamment la formation d'acĂ©tates d'Ă©nol chiraux comme alternative Ă la synthĂšse d'Ă©thers d'Ă©nol silylĂ©s. Enfin, l'utilisation ultĂ©rieure des adduits possĂ©dant un centre quaternaire chiral est envisagĂ©e afin de trouver diverses applications Ă la mĂ©thodologie dĂ©veloppĂ©e, alors qu'une nouvelle rĂ©action tandem d'hydroalumination-A.C.A. est mise au point
Caractérisation de la dynamique de l'ADN-glycosylase OGG1 et de résidus responsables de son interaction avec l'ADN en cellules vivantes
DNA is constantly subjected to various stress, threatening its integrity, and consequently, the proper functioning of the cell. In order to preserve the genomic integrity, the cell can activate a large set of repair pathways. One of the most common genomic alteration is the base modification 8-oxoguanine (8-oxoG), an oxidized form of guanine. It is highly mutagenic, due to its tendency to pair with adenine instead of cytosine during replication. Thus, it needs to be detected and repaired on time to avoid G:C to T:A transversions. 8-oxoG paired with cytosine is recognized and excised by the 8-oxoguanine DNA-glycosylase (OGG1), which initiates the base excision repair pathway. Although OGG1 has been widely studied in vitro and many structural data are available, many questions remain concerning the dynamics of the protein within the cell nucleus. Hence, the goal of my PhD project was to characterize the dynamics of OGG1 searching for 8-oxoG and get new insights about the residues or functions of OGG1 that regulate these dynamics. I was able to show that the interaction between OGG1 and DNA is crucial for the efficient search of 8-oxoG, and that mutating the residues involved in such interaction impairs OGG1 dynamics and its ability to detect and excise 8-oxoG. Similarly, 8-oxoG detection, but also that of the facing cytosine, both play an important role in the function of the DNA-glycosylase and in its ability to accumulate at the sites of damage. Finally, the NNN motif, which is highly conserved but very poorly characterized, seems to be essential to the specific association with 8-oxoG, but not for the nuclear exploration by OGG1.LâADN est constamment soumis Ă de nombreux stress, menaçant son intĂ©gritĂ© et, par consĂ©quent, le bon fonctionnement cellulaire. Pour y faire face, la cellule dispose de tout un arsenal de voies de rĂ©paration. Lâune des altĂ©ration du gĂ©nome les plus frĂ©quentes est lâoxydation de la guanine en 8-oxoguanine (8-oxoG). La 8-oxoG possĂšde un fort potentiel mutagĂšne du fait de son appariement prĂ©fĂ©rentiel avec lâadĂ©nine au lieu de la cytosine lors de la rĂ©plication. Ainsi, elle doit ĂȘtre dĂ©tectĂ©e et rĂ©parĂ©e Ă temps pour Ă©viter la fixation dans le gĂ©nome de mutation par transversion G:C vers T:A. Cette lĂ©sion appairĂ©e Ă une cytosine est dĂ©tectĂ©e et excisĂ©e par la 8-oxoguanine ADN-glycosylase (OGG1), ce qui initie la rĂ©paration par excision de base. Si le fonctionnement dâOGG1 a Ă©tĂ© largement Ă©tudiĂ© in vitro et que de nombreuses donnĂ©es structurales sont disponibles, trĂšs peu dâĂ©tudes se sont penchĂ©es sur la dynamique de cette protĂ©ine au sein du noyau cellulaire. Le but de ma thĂšse Ă©tait donc de caractĂ©riser la dynamique de recherche de la 8-oxoG par OGG1 et dâidentifier les Ă©lĂ©ments (rĂ©sidus ou fonctions) rĂ©gulant cette dynamique. Ainsi, jâai pu montrer que lâinteraction avec lâADN Ă©tait un Ă©lĂ©ment majeur de la recherche de la 8-oxoG par OGG1, et que muter les rĂ©sidus impliquĂ©s dans lâinteraction avec lâADN perturbait la dynamique dâOGG1 et sa capacitĂ© Ă trouver et exciser la 8-oxoG. De mĂȘme, la reconnaissance de la 8-oxoG, mais Ă©galement celle de la cytosine lui faisant face, jouent toutes deux un rĂŽle important dans le fonctionnement de lâADN-glycosylase et son recrutement Ă la zone de dommages. Enfin, le motif NNN, trĂšs conservĂ© mais trĂšs peu caractĂ©risĂ© jusquâici semble ĂȘtre essentiel Ă lâassociation spĂ©cifique avec la 8-oxoG mais pas Ă la dynamique de recherche
Characterization of the dynamics of the DNA-glycosylase OGG1 and of residues responsible for its interaction with DNA in living cells
LâADN est constamment soumis Ă de nombreux stress, menaçant son intĂ©gritĂ© et, par consĂ©quent, le bon fonctionnement cellulaire. Pour y faire face, la cellule dispose de tout un arsenal de voies de rĂ©paration. Lâune des altĂ©ration du gĂ©nome les plus frĂ©quentes est lâoxydation de la guanine en 8-oxoguanine (8-oxoG). La 8-oxoG possĂšde un fort potentiel mutagĂšne du fait de son appariement prĂ©fĂ©rentiel avec lâadĂ©nine au lieu de la cytosine lors de la rĂ©plication. Ainsi, elle doit ĂȘtre dĂ©tectĂ©e et rĂ©parĂ©e Ă temps pour Ă©viter la fixation dans le gĂ©nome de mutation par transversion G:C vers T:A. Cette lĂ©sion appairĂ©e Ă une cytosine est dĂ©tectĂ©e et excisĂ©e par la 8-oxoguanine ADN-glycosylase (OGG1), ce qui initie la rĂ©paration par excision de base. Si le fonctionnement dâOGG1 a Ă©tĂ© largement Ă©tudiĂ© in vitro et que de nombreuses donnĂ©es structurales sont disponibles, trĂšs peu dâĂ©tudes se sont penchĂ©es sur la dynamique de cette protĂ©ine au sein du noyau cellulaire. Le but de ma thĂšse Ă©tait donc de caractĂ©riser la dynamique de recherche de la 8-oxoG par OGG1 et dâidentifier les Ă©lĂ©ments (rĂ©sidus ou fonctions) rĂ©gulant cette dynamique. Ainsi, jâai pu montrer que lâinteraction avec lâADN Ă©tait un Ă©lĂ©ment majeur de la recherche de la 8-oxoG par OGG1, et que muter les rĂ©sidus impliquĂ©s dans lâinteraction avec lâADN perturbait la dynamique dâOGG1 et sa capacitĂ© Ă trouver et exciser la 8-oxoG. De mĂȘme, la reconnaissance de la 8-oxoG, mais Ă©galement celle de la cytosine lui faisant face, jouent toutes deux un rĂŽle important dans le fonctionnement de lâADN-glycosylase et son recrutement Ă la zone de dommages. Enfin, le motif NNN, trĂšs conservĂ© mais trĂšs peu caractĂ©risĂ© jusquâici semble ĂȘtre essentiel Ă lâassociation spĂ©cifique avec la 8-oxoG mais pas Ă la dynamique de recherche.DNA is constantly subjected to various stress, threatening its integrity, and consequently, the proper functioning of the cell. In order to preserve the genomic integrity, the cell can activate a large set of repair pathways. One of the most common genomic alteration is the base modification 8-oxoguanine (8-oxoG), an oxidized form of guanine. It is highly mutagenic, due to its tendency to pair with adenine instead of cytosine during replication. Thus, it needs to be detected and repaired on time to avoid G:C to T:A transversions. 8-oxoG paired with cytosine is recognized and excised by the 8-oxoguanine DNA-glycosylase (OGG1), which initiates the base excision repair pathway. Although OGG1 has been widely studied in vitro and many structural data are available, many questions remain concerning the dynamics of the protein within the cell nucleus. Hence, the goal of my PhD project was to characterize the dynamics of OGG1 searching for 8-oxoG and get new insights about the residues or functions of OGG1 that regulate these dynamics. I was able to show that the interaction between OGG1 and DNA is crucial for the efficient search of 8-oxoG, and that mutating the residues involved in such interaction impairs OGG1 dynamics and its ability to detect and excise 8-oxoG. Similarly, 8-oxoG detection, but also that of the facing cytosine, both play an important role in the function of the DNA-glycosylase and in its ability to accumulate at the sites of damage. Finally, the NNN motif, which is highly conserved but very poorly characterized, seems to be essential to the specific association with 8-oxoG, but not for the nuclear exploration by OGG1
Caractérisation de la dynamique de l'ADN-glycosylase OGG1 et de résidus responsables de son interaction avec l'ADN en cellules vivantes
DNA is constantly subjected to various stress, threatening its integrity, and consequently, the proper functioning of the cell. In order to preserve the genomic integrity, the cell can activate a large set of repair pathways. One of the most common genomic alteration is the base modification 8-oxoguanine (8-oxoG), an oxidized form of guanine. It is highly mutagenic, due to its tendency to pair with adenine instead of cytosine during replication. Thus, it needs to be detected and repaired on time to avoid G:C to T:A transversions. 8-oxoG paired with cytosine is recognized and excised by the 8-oxoguanine DNA-glycosylase (OGG1), which initiates the base excision repair pathway. Although OGG1 has been widely studied in vitro and many structural data are available, many questions remain concerning the dynamics of the protein within the cell nucleus. Hence, the goal of my PhD project was to characterize the dynamics of OGG1 searching for 8-oxoG and get new insights about the residues or functions of OGG1 that regulate these dynamics. I was able to show that the interaction between OGG1 and DNA is crucial for the efficient search of 8-oxoG, and that mutating the residues involved in such interaction impairs OGG1 dynamics and its ability to detect and excise 8-oxoG. Similarly, 8-oxoG detection, but also that of the facing cytosine, both play an important role in the function of the DNA-glycosylase and in its ability to accumulate at the sites of damage. Finally, the NNN motif, which is highly conserved but very poorly characterized, seems to be essential to the specific association with 8-oxoG, but not for the nuclear exploration by OGG1.LâADN est constamment soumis Ă de nombreux stress, menaçant son intĂ©gritĂ© et, par consĂ©quent, le bon fonctionnement cellulaire. Pour y faire face, la cellule dispose de tout un arsenal de voies de rĂ©paration. Lâune des altĂ©ration du gĂ©nome les plus frĂ©quentes est lâoxydation de la guanine en 8-oxoguanine (8-oxoG). La 8-oxoG possĂšde un fort potentiel mutagĂšne du fait de son appariement prĂ©fĂ©rentiel avec lâadĂ©nine au lieu de la cytosine lors de la rĂ©plication. Ainsi, elle doit ĂȘtre dĂ©tectĂ©e et rĂ©parĂ©e Ă temps pour Ă©viter la fixation dans le gĂ©nome de mutation par transversion G:C vers T:A. Cette lĂ©sion appairĂ©e Ă une cytosine est dĂ©tectĂ©e et excisĂ©e par la 8-oxoguanine ADN-glycosylase (OGG1), ce qui initie la rĂ©paration par excision de base. Si le fonctionnement dâOGG1 a Ă©tĂ© largement Ă©tudiĂ© in vitro et que de nombreuses donnĂ©es structurales sont disponibles, trĂšs peu dâĂ©tudes se sont penchĂ©es sur la dynamique de cette protĂ©ine au sein du noyau cellulaire. Le but de ma thĂšse Ă©tait donc de caractĂ©riser la dynamique de recherche de la 8-oxoG par OGG1 et dâidentifier les Ă©lĂ©ments (rĂ©sidus ou fonctions) rĂ©gulant cette dynamique. Ainsi, jâai pu montrer que lâinteraction avec lâADN Ă©tait un Ă©lĂ©ment majeur de la recherche de la 8-oxoG par OGG1, et que muter les rĂ©sidus impliquĂ©s dans lâinteraction avec lâADN perturbait la dynamique dâOGG1 et sa capacitĂ© Ă trouver et exciser la 8-oxoG. De mĂȘme, la reconnaissance de la 8-oxoG, mais Ă©galement celle de la cytosine lui faisant face, jouent toutes deux un rĂŽle important dans le fonctionnement de lâADN-glycosylase et son recrutement Ă la zone de dommages. Enfin, le motif NNN, trĂšs conservĂ© mais trĂšs peu caractĂ©risĂ© jusquâici semble ĂȘtre essentiel Ă lâassociation spĂ©cifique avec la 8-oxoG mais pas Ă la dynamique de recherche
Estimates of Effective Population Size and Inbreeding Level for Three Australian Pig Breeds
Selective breeding may result in higher inbreeding levels which can lead to inbreeding depression and limit future genetic gain. This study quantified inbreeding levels and evaluated effective population sizes for Large White (LW), Landrace (LR) and Duroc (DU) populations in Australia. Pedigree data from 1994 to 2015 representing about 12 generations on average were explored with the software package PopRep by Groeneveld et al. (2009) which provides multiple population parameters. Pedigree completeness was highest in 2004 and 2005 when it reached about 95% and 80% in the third and sixth generation. Average inbreeding levels were highest for these years with averages of 0.031, 0.034 and 0.050 in LW, LR and DU, respectively. Two herds joined the across-herd genetic evaluations at that time and pedigree completeness varied from 80 to 90% and from 60 to 70% in the third and sixth generation in subsequent years leading to lower estimates of inbreeding levels. Estimates of effective population size varied from 64 to 98 in LW, from 52 to 108 in LR and from 42 to 61 in DU over time. These estimates of effective population size are imprecise and an underestimate of true effective population sizes given the limited time period considered and the extent of missing pedigree
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