Publications des biologistes du forum

[Yoyo]

Bonjour,

Devant le nombre croissant de messages concernant des publications de membres dans la discussion Articles importants dans Nature, Science ou Cell, nous avons décidé de créer une nouvelle discussion exclusivement réservée aux publications des membres biologistes du forum. Tous les messages concernés ont été déplacés dans cette nouvelle discussion. Les règles sont les mêmes que pour la discussion précédente sauf que ce n'est pas limité qu'aux journaux de prestige (Nature, Science, Cell), et le forumeur qui poste la publication doit être co-auteur.

LXR

[Yoyo]

Allez, je resiste pas

Un super article qui identifie le premier gène dont l'expression est régulée par une protéine de type prion

Nature Cell Biology
Published online: 1 August 2008 | doi:10.1038/ncb1766

Epigenetic control of polyamines by the prion [PSI+]

Olivier Namy, Aurélie Galopier, Cyrielle Martini, Senya Matsufuji, Céline Fabret & Jean-Pierre Rousset

Prion proteins are found in mammals and yeast, and can transmit diseases and encode heritable phenotypic traits1. In Saccharomyces cerevisiae, eRF3, Rnq1, Ure2 and Swi1 are functional proteins with a soluble conformation that can switch to a non-functional, amyloid conformation denoted as [PSI+], [PIN+], [URE3] and [SWI+], respectively2, 3. The prion [PSI+] corresponds to an aggregated conformation of the translational release factor eRF3, which suppresses nonsense codons2. [PSI+] modifies cellular fitness and induces several phenotypes according to the genetic background4, 5. An elegant series of studies has demonstrated that several [PSI+]-induced phenotypes occur as a consequence of decreased translational termination efficiency6, 7. However, the genes whose expression levels are controlled by [PSI+] remain largely unknown. Here, we show that [PSI+] enhances expression of antizyme, a negative regulator of cellular polyamines, by modulating the +1 frameshifting required for its expression8. Our study also demonstrates that [PSI+] greatly affects cellular polyamines in yeast. We show that modification of the cellular content of polyamines by the prion accounts for half of the [PSI+]-induced phenotypes. Antizyme is the first protein to be described for which expression in its functional form is stimulated by [PSI+].

c'est accessible ici (pour ceux qui ont l'abonnement)
http://www.nature.com/ncb/journal/va...s/ncb1766.html

Bonne lecture
YOyo

[MaliciaR]

Bravo, Yoyo!

[John78]

Ca baisse quand même Yoyo, passer de Nature a Nature Cell Biol c'est la mauvaise pente, il faut se ressaisir là

(simple apparté)

Revenons a nos moutons.

A+
J

[piwi]

Un maaaAAAÂAAAaaagnifique article tout frais:

STRA8-deficient spermatocytes initiate, but fail to complete, meiosis and undergo premature chromosome condensation
Manuel Mark*, Hugues Jacobs, Mustapha Oulad-Abdelghani, Christine Dennefeld, Betty Féret, Nadège Vernet, Carmen-Alina Codreanu, Pierre Chambon and Norbert B. Ghyselinck*
Journal of Cell Science 121, 3233-3242 (2008)
http://jcs.biologists.org/cgi/conten...ct/121/19/3233

abstract:
We analysed the phenotypic outcome of a Stra8-null mutation on male meiosis. Because the mutant spermatocytes (1) underwent premeiotic DNA replication, (2) displayed cytological features attesting initiation of recombination and of axial-element assembly, and (3) expressed Spo11 and numerous other meiotic genes, it was concluded that STRA8 is dispensable for meiotic initiation. The few mutant spermatocytes that progressed beyond leptonema showed a prolonged bouquet-stage configuration, asynapsis and heterosynapsis, suggesting function(s) of STRA8 in chromosome pairing. Most importantly, a large number of mutant leptotene spermatocytes underwent premature chromosome condensation, within 24 hours following the meiotic S phase. This phenomenon yielded aberrant metaphase-like cells with 40 univalent chromosomes, similar to normal mitotic metaphases. From these latter observations and from the wild-type pattern of Stra8 expression, we propose that, in preleptotene spermatocytes, STRA8 is involved in the process that leads to stable commitment to the meiotic cell cycle.

Bon c'est pas nature ni même nature cell biol.
Mais bon, on a beaucoup réfléchi et on c'est dit qu'il ne fallait pas frustrer le chef, alors on c'est écrasé...
Personne me croit? Curieux.
Bon c'est pas grave. Même si il ne révolutionne pas absolument la science, sa gestation a été tellement difficile qu'on a pensé un moment à picsou magazine. Du coup J. Cell Science c'est quand même la classe

[LXR]

Ce qui est la classe aussi c'est d'avoir son nom aux côtés de celui de Pierre Chambon.

Greg

[Patfol]

Félicitation Piwi, et ça fais une de plus pour l'IGBMC

[jmbowie]

Tout est équilibre, cette fois ce sont des éléments génétiques de bactéries qui nous le rappellent.
L'article décrit la corrélation inverse entre expression et mobilité des gènes de résistances aux antibiotiques portée par les intégrons.
Bonne lecture, gratuite et en ligne:

http://www.plosgenetics.org/article/...l.pgen.1000793

[LXR]

Voici un superbe article publié dans PNAS où on montre qu'un hétérodimère de deux enzymes donne une nouvelle activité enzymatique qui n'est représentée que par cet hétérodimère.

Proc Natl Acad Sci U S A. 2010 Jul 6. [Epub ahead of print]
Identification and pharmacological characterization of cholesterol-5,6-epoxide hydrolase as a target for tamoxifen and AEBS ligands.

de Medina P, Paillasse MR, Segala G, Poirot M, Silvente-Poirot S.

Institut National de la Santé et de la Recherche Médicale, U563, Equipe: Métabolisme, Oncogenése et Différenciation Cellulaire, 31052 Toulouse, France.
Abstract

The microsomal antiestrogen binding site (AEBS) is a high-affinity target for the antitumor drug tamoxifen and its cognate ligands that mediate breast cancer cell differentiation and apoptosis. The AEBS, a hetero-oligomeric complex composed of 3beta-hydroxysterol-Delta(8)-Delta(7)-isomerase (D8D7I) and 3beta-hydroxysterol-Delta(7)-reductase (DHCR7), binds different structural classes of ligands, including ring B oxysterols. These oxysterols are inhibitors of cholesterol-5,6-epoxide hydrolase (ChEH), a microsomal epoxide hydrolase that has yet to be molecularly identified. We hypothesized that the AEBS and ChEH might be related entities. We show that the substrates of ChEH, cholestan-5alpha,6alpha-epoxy-3beta-ol (alpha-CE) and cholestan-5beta,6beta-epoxy-3beta-ol (beta-CE), and its product, cholestane-3beta,5alpha,6beta-triol (CT), are competitive ligands of tamoxifen binding to the AEBS. Conversely, we show that each AEBS ligand is an inhibitor of ChEH activity, and that there is a positive correlation between these ligands' affinity for the AEBS and their potency to inhibit ChEH (r(2) = 0.95; n = 39; P < 0.0001). The single expression of D8D7I or DHCR7 in COS-7 cells slightly increased ChEH activity (1.8- and 2.6-fold), whereas their coexpression fully reconstituted ChEH, suggesting that the formation of a dimer is required for ChEH activity. Similarly, the single knockdown of D8D7I or DHCR7 using siRNA partially inhibited ChEH in MCF-7 cells, whereas the knockdown of both D8D7I and DHCR7 abolished ChEH activity by 92%. Taken together, our findings strongly suggest that the AEBS carries out ChEH activity and establish that ChEH is a new target for drugs of clinical interest, polyunsaturated fatty acids and ring B oxysterols.

Enjoy!

[mantOs]

Un peu d'auto-satisfaction vu la difficulté à le faire passer.

Démonstration in vitro et in silicoque l'intégration de HIV-1 ne peut se faire dans une chromatine dense et stable et que la présence de nucléosomes peut être réfractaire à l'intégration.
On renverse ici, avec des manips plus précises et proche de la physiologie, le dogme admis il y a 15 ans.

http://www.plospathogens.org/article...C4C38C.ambra02

PLoS Pathog. 2011 Feb 10;7(2):e1001280.

Functional coupling between HIV-1 integrase and the SWI/SNF chromatin remodeling complex for efficient in vitro integration into stable nucleosomes.

Lesbats P, Botbol Y, Chevereau G, Vaillant C, Calmels C, Arneodo A, Andreola ML, Lavigne M, Parissi V.

Laboratoire MCMP, UMR 5234 CNRS-Université Victor Segalen Bordeaux 2, Bordeaux, France.
Abstract

Establishment of stable HIV-1 infection requires the efficient integration of the retroviral genome into the host DNA. The molecular mechanism underlying the control of this process by the chromatin structure has not yet been elucidated. We show here that stably associated nucleosomes strongly inhibit in vitro two viral-end integration by decreasing the accessibility of DNA to integrase. Remodeling of the chromatinized template by the SWI/SNF complex, whose INI1 major component interacts with IN, restores and redirects the full-site integration into the stable nucleosome region. These effects are not observed after remodeling by other human remodeling factors such as SNF2H or BRG1 lacking the integrase binding protein INI1. This suggests that the restoration process depends on the direct interaction between IN and the whole SWI/SNF complex, supporting a functional coupling between the remodeling and integration complexes. Furthermore, in silico comparison between more than 40,000 non-redundant cellular integration sites selected from literature and nucleosome occupancy predictions also supports that HIV-1 integration is promoted in the genomic region of weaker intrinsic nucleosome density in the infected cell. Our data indicate that some chromatin structures can be refractory for integration and that coupling between nucleosome remodeling and HIV-1 integration is required to overcome this natural barrier.

[LXR]

Félicitations c'est un bon journal! Sans grand étonnement, je vois que les supplementary data représentent une publie supplémentaire. Les exigences sont désormais énormes! Si tu souhaites la commenter (et si tu as le temps) dans la rubrique "vos publications" du forum, n'hésites pas.

[mantOs]

Félicitations c'est un bon journal! Sans grand étonnement, je vois que les supplementary data représentent une publie supplémentaire. Les exigences sont désormais énormes! Si tu souhaites la commenter (et si tu as le temps) dans la rubrique "vos publications" du forum, n'hésites pas.

Sans problème. Là je me suis payé un week end prolongé (vu le temps) je fais ça la semaine prochaine.

[LXR]

Si cela vous intéresse, Mantos a écrit un résumé "grand public" de sa publication dans la rubrique dédiée : http://forums.futura-sciences.com/vo...n-dogmeoe.html