RESUMEN
Premature telomere shortening or telomere instability is associated with a group of rare and heterogeneous diseases collectively known as telomere biology disorders (TBDs). Here we identified two unrelated individuals with clinical manifestations of TBDs and short telomeres associated with the identical monoallelic variant c.767A>G; Y256C in RPA2 Although the replication protein A2 (RPA2) mutant did not affect ssDNA binding and G-quadruplex-unfolding properties of RPA, the mutation reduced the affinity of RPA2 with the ubiquitin ligase RFWD3 and reduced RPA ubiquitination. Using engineered knock-in cell lines, we found an accumulation of RPA at telomeres that did not trigger ATR activation but caused short and dysfunctional telomeres. Finally, both patients acquired, in a subset of blood cells, somatic genetic rescue events in either POT1 genes or TERT promoters known to counteract the accelerated telomere shortening. Collectively, our study indicates that variants in RPA2 represent a novel genetic cause of TBDs. Our results further support the fundamental role of the RPA complex in regulating telomere length and stability in humans.
Asunto(s)
Proteína de Replicación A , Proteínas de Unión a Telómeros , Telómero , Humanos , Proteína de Replicación A/genética , Proteína de Replicación A/metabolismo , Telómero/genética , Proteínas de Unión a Telómeros/genética , Proteínas de Unión a Telómeros/metabolismo , Heterocigoto , Masculino , Femenino , Complejo Shelterina , Acortamiento del Telómero/genética , Mutación , Telomerasa/genética , Telomerasa/metabolismo , Ubiquitinación/genética , Ubiquitina-Proteína Ligasas/genéticaRESUMEN
Identification of a common Diels-Alder pattern in three classes of bioactive natural products led us to study the synthesis and cycloaddition of a new class of cyclic dienes readily available from ß,γ-unsaturated lactams. A practical and readily scalable route to the parent p-methoxybenzyl-protected 6- and 7-membered ß,γ-unsaturated lactams was developed. These were readily transformed into the corresponding O-silylated dienes, which were reacted with dimethyl and diethyl fumarate to yield stereoselectively highly functionalized bicyclic adducts. These exhibited unexpected and versatile transformations upon acid hydrolysis depending on the nature of the dienophile substituents and the acid catalyst. All reactions have been performed on multigram quantities. These transformations provide a convenient, economical, and easily scalable pathway for the rapid construction of functionally and stereochemically dense privileged scaffolds for the construction of libraries of natural products-inspired molecules of pharmacological relevance.
Asunto(s)
Productos Biológicos , Productos Biológicos/síntesis química , Productos Biológicos/química , Catálisis , Reacción de Cicloadición , Hidrólisis , Lactamas/químicaRESUMEN
Herein, we report a convenient synthesis of unprecedented aza-diketopiperazines (aza-DKPs). The strategy is based on selective diversification of bicyclic aza-DKP scaffolds by click reaction, N-acylation, and/or N-alkylation. These scaffolds containing either azido or amino groups were obtained by a key Rh(I)-catalyzed hydroformylative cyclohydrocarbonylation reaction of allyl-substituted aza-DKP. The methodology is readily amenable to the parallel synthesis of original aza-DKPs to enlarge the chemical diversity of aza-heterocycles.
RESUMEN
Thermic dimerization of methyl 1,3-cyclohexadiene 2-carboxylate gave original 3D-shape compounds by Diels-Alder cycloaddition and original [6 + 4]-ene reaction. Further selective modifications on an endo [4 + 2] cycloadduct via a diversity oriented synthesis (DOS) strategy quickly led to the preparation of a small library of original 3D scaffolds, providing access to a larger and unexplored chemical space for drug discovery processes.
RESUMEN
A patient with chronic lymphocytic leukaemia (CLL) progressive on fludarabine therapy and life-threatening anaemia related to immune haemolysis and pure red cell aplasia was treated with Campath-1H. The patient had sustained complete remission of both CLL and anaemia, but died of recurrent sepsis and cachexia 10 months after completion of the treatment. Campath-1H (alemtuzumab), a humanised anti-CD52 monoclonal antibody, is a potent therapeutic agent against advanced CLL and immune cytopenias. It could be indicated in the treatment of severe immune complications of CLL unresponsive to corticosteroids. Prolonged immunosuppression is a serious side-effect leading to severe infectious complication.