Crystallization and preliminary X-ray diffraction studies of D-glyceraldehyde-3-phosphate dehydrogenase from the hyperthermophilic archaeon Methanothermus fervidus.

Journal ArticleThe homotetrameric holo-D-glyceraldehyde-3-phosphate dehydrogenase from the hyperthermophilic archaeon Methanothermus fervidus has been crystallized in the presence of NADP+ using the hanging-drop vapour-diffusion method. Crystals grew from a solution containing 2-methyl-2,4-pentanediol and magnesium acetate. A native data set has been collected to 2.1 A using synchrotron radiation and cryocooling. Diffraction data have been processed in the orthorhombic system (space group P21212) with unit-cell dimensions a = 136.7, b = 153.3, c = 74.9 A and one tetramer per asymmetric unit

In Vitro Transformation of Primary Human CD34+ Cells by AML Fusion Oncogenes: Early Gene Expression Profiling Reveals Possible Drug Target in AML

Different fusion oncogenes in acute myeloid leukemia (AML) have distinct clinical and laboratory features suggesting different modes of malignant transformation. Here we compare the in vitro effects of representatives of 4 major groups of AML fusion oncogenes on primary human CD34+ cells. As expected from their clinical similarities, MLL-AF9 and NUP98-HOXA9 had very similar effects in vitro. They both caused erythroid hyperplasia and a clear block in erythroid and myeloid maturation. On the other hand, AML1-ETO and PML-RARA had only modest effects on myeloid and erythroid differentiation. All oncogenes except PML-RARA caused a dramatic increase in long-term proliferation and self-renewal. Gene expression profiling revealed two distinct temporal patterns of gene deregulation. Gene deregulation by MLL-AF9 and NUP98-HOXA9 peaked 3 days after transduction. In contrast, the vast majority of gene deregulation by AML1-ETO and PML-RARA occurred within 6 hours, followed by a dramatic drop in the numbers of deregulated genes. Interestingly, the p53 inhibitor MDM2 was upregulated by AML1-ETO at 6 hours. Nutlin-3, an inhibitor of the interaction between MDM2 and p53, specifically inhibited the proliferation and self-renewal of primary human CD34+ cells transduced with AML1-ETO, suggesting that MDM2 upregulation plays a role in cell transformation by AML1-ETO. These data show that differences among AML fusion oncogenes can be recapitulated in vitro using primary human CD34+ cells and that early gene expression profiling in these cells can reveal potential drug targets in AML

N-Méthyl peptides. VIII étude radiocristallographique du repliement ßVI des séquences homochirales

Les structures cristallines des deux dipeptides tBuCO-L-Pro-Me-L-X-NHMe avec X = Leu et Phe ont été résolues par diffraction des rayons X. Tous deux adoptent la forme repliée βVI caractérisée par une liaison hydrogène unissant les sites NH et CO extrêmes et par une conformation cis de la liaison amide médiane N-méthylée. Il apparaît que ce type de repliement est particulièrement favorisé dans le cas d'une séquence peptidique homochirale N-méthylée

Mise au point Modulations conformationnelles du repliement β en serie peptidique et pseudopeptidique

L'unité structurale appelée repliement β dans les peptides et les protéines concerne une courte séquence de quatre résidus peptidiques qui est le siège d'une liaison hydrogène N — H...O = C fermant un cycle à dix atomes. Ce motif permet une inversion de la direction de propagation de la chaîne peptidique et constitue une zone exposée aux contacts intermoléculaires.L'une des voies de recherche en matière d’utilisation thérapeutique des peptides consiste à ralentir leur degradation enzymatique par modification chimique du squelette peptidique Cα—CO —NH. Toutefois, il peut aussi en résulter un changement des propriétés conformationnelles, propice ou néfaste à l’effet recherché. La présente revue examine l'influence de telles modifications sur la stabilité du repliement β. Certaines ont fait l'objet de nombreuses études (inversion de la configuration du carbone Cα, Cα-méthylation...), mais la plupart ont été peu examinées d'un point de vue conformationnel.L'examen de composés dérivés de la séquence minimale pour la réalisation du repliement β fournit des informations précises sur l'influence des diverses modifications introduites dans les analogues des peptides. Les résultats de ces études spectroscopiques (IR et RMN) en solution et radiocristallographiques sur l'état solide sont présentés et complétés par les observations rapportées dans la littérature

Ameaça de desastre ou risco dominado? Uma abordagem geo-histórica do risco de inundação em áreas urbanas.: Exemplo de Mulhouse (França)

The Prevention Plan against Flood Risks in the Ill Basin reveals that the city of Mulhouse (France) is almost entirely free from flood nuisance. This situation appears to result from the building of an important diversion canal for the Ill river during the second half of the 19th century. To improve the undeniable efficiency of the canal, we adopt a historical and geographical perspective at different scales in order to place the devastating floods as well as the urban and river system of protection in a broader context. Those results proceed from the studies carried out within the framework of the French-German program TRANSRISK, financed by the ANR and the DFG.O Plano de Prevenção dos riscos de inundação na bacia do Ill revela que a cidade de Mulhouse (França) está quase totalmente fora de perigo de inundações. Esta situação parece ser o resultado da construção de um importante canal de derivação durante a segunda metade do século XIX. Para avaliar a sua eficiência incontestável, adoptamos uma abordagem histórica e geográfica sistémica e em diferentes escalas com o objetivo de contextualizar a evolução das inundações devastadoras e do sistema de proteção. Estes trabalhos foram realizados no âmbito do programa francoalemão TRANSRISK, financiado pela ANR e pela DFG

Rexinoid-triggered differentiation and tumor-selective apoptosis of acute myeloid leukemia by protein kinase A-mediated desubordination of retinoid X receptor.

Apart from PML-retinoic acid receptor-alpha (RAR alpha) acute promyelocytic leukemia all other acute myeloid leukemias (AML) are unresponsive to retinoid differentiation therapy. However, elevating the levels of cyclic AMP (cAMP) confers onto retinoid X receptor (RXR)-selective agonists ("rexinoids") the ability to induce terminal granulocyte differentiation and apoptosis of all-trans retinoic acid-resistant and insensitive AML cells and patients' blasts. Protein kinase A activation leads to corepressor release from the RAR subunit of the RAR-RXR heterodimer, resulting in "desubordination" of otherwise silent RXR, which acquires transcriptional competence in response to cognate ligands. Rexinoid-cAMP induction of endogenous RAR beta is blunted in mouse embryo fibroblasts lacking RARs, but reintroduction of exogenous RAR alpha reestablishes responsiveness, thus confirming that the RAR alpha-RXR heterodimer is the rexinoid mediator. The apoptogenic effect of this treatment involves enhanced expression of the death receptor DR5 and its cognate ligand, tumor necrosis factor-related apoptosis inducing ligand, both of which are known to induce apoptosis in a tumor cell-selective manner and lead to the activation of initiator caspases. Inummohistochemistry confirmed induction of tumor necrosis factor-related apoptosis inducing ligand and DR5 in AML patient blasts cultured ex vivo. AML patients' blasts responded to rexinoid-cAMP combination treatment with induction of maturation and apoptosis, independent of karyotype, immunophenotype, and French-American-British classification status. Clonogenic assays revealed complete inhibition of blast clonogenicity in four out of five tested samples. Our results suggest that despite the genetic, morphologic, and clinical variability of this disease, the combination of rexinoids and cAMP-elevating drugs, such as phosphodiesterase inhibitors, might lead to a novel therapeutic option for AML patients by inducing a tumor-selective death pathwa