Autophagy mediates degradation of nuclear lamina

Z.D. is supported by a fellow award from the Leukemia & Lymphoma Society. B.C.C. is supported by career development awards from the Dermatology Foundation, Melanoma Research Foundation, and American Skin Association. S.L.B., P.D.A. and R.M. are supported by NIA P01 grant (P01AG031862). S.L.B. is also supported by NIH R01 CA078831. R.D.G. is supported by R01 GM106023 and the Progeria Research Foundation

Comparative Analysis of DNA Replication Timing Reveals Conserved Large-Scale Chromosomal Architecture

Recent evidence suggests that the timing of DNA replication is coordinated across megabase-scale domains in metazoan genomes, yet the importance of this aspect of genome organization is unclear. Here we show that replication timing is remarkably conserved between human and mouse, uncovering large regions that may have been governed by similar replication dynamics since these species have diverged. This conservation is both tissue-specific and independent of the genomic G+C content conservation. Moreover, we show that time of replication is globally conserved despite numerous large-scale genome rearrangements. We systematically identify rearrangement fusion points and demonstrate that replication time can be locally diverged at these loci. Conversely, rearrangements are shown to be correlated with early replication and physical chromosomal proximity. These results suggest that large chromosomal domains of coordinated replication are shuffled by evolution while conserving the large-scale nuclear architecture of the genome

Selective sigma-2 ligands preferentially bind to pancreatic adenocarcinomas: applications in diagnostic imaging and therapy

<p>Abstract</p> <p>Background</p> <p>Resistance to modern adjuvant treatment is in part due to the failure of programmed cell death. Therefore the molecules that execute the apoptotic program are potential targets for the development of anti-cancer therapeutics. The sigma-2 receptor has been found to be over-expressed in some types of malignant tumors, and, recently, small molecule ligands to the sigma-2 receptor were found to induce cancer cell apoptosis.</p> <p>Results</p> <p>The sigma-2 receptor was expressed at high levels in both human and murine pancreas cancer cell lines, with minimal or limited expression in normal tissues, including: brain, kidney, liver, lung, pancreas and spleen. Micro-PET imaging was used to demonstrate that the sigma-2 receptor was preferentially expressed in tumor as opposed to normal tissues in pancreas tumor allograft-bearing mice. Two structurally distinct sigma-2 receptor ligands, SV119 and WC26, were found to induce apoptosis to mice and human pancreatic cancer cells <it>in vitro </it>and <it>in vivo</it>. Sigma-2 receptor ligands induced apoptosis in a dose dependent fashion in all pancreatic cell lines tested. At the highest dose tested (10 μM), all sigma-2 receptor ligands induced 10–20% apoptosis in all pancreatic cancer cell lines tested (p < 0.05). In pancreas tumor allograft-bearing mice, a single bolus dose of WC26 caused approximately 50% apoptosis in the tumor compared to no appreciable apoptosis in tumor-bearing, vehicle-injected control animals (p < 0.0001). WC26 significantly slowed tumor growth after a 5 day treatment compared to vehicle-injected control animals (p < 0.0001) and blood chemistry panels suggested that there is minimal peripheral toxicity.</p> <p>Conclusion</p> <p>We demonstrate a novel therapeutic strategy that induces a significant increase in pancreas cancer cell death. This strategy highlights a new potential target for the treatment of pancreas cancer, which has little in the way of effective treatments.</p

FSHD: copy number variations on the theme of muscular dystrophy

In humans, copy number variations (CNVs) are a common source of phenotypic diversity and disease susceptibility. Facioscapulohumeral muscular dystrophy (FSHD) is an important genetic disease caused by CNVs. It is an autosomal-dominant myopathy caused by a reduction in the copy number of the D4Z4 macrosatellite repeat located at chromosome 4q35. Interestingly, the reduction of D4Z4 copy number is not sufficient by itself to cause FSHD. A number of epigenetic events appear to affect the severity of the disease, its rate of progression, and the distribution of muscle weakness. Indeed, recent findings suggest that virtually all levels of epigenetic regulation, from DNA methylation to higher order chromosomal architecture, are altered at the disease locus, causing the de-regulation of 4q35 gene expression and ultimately FSHD

From lamins to lamina: a structural perspective

Lamin proteins are the major constituents of the nuclear lamina, a proteinaceous network that lines the inner nuclear membrane. Primarily, the nuclear lamina provides structural support for the nucleus and the nuclear envelope; however, lamins and their associated proteins are also involved in most of the nuclear processes, including DNA replication and repair, regulation of gene expression, and signaling. Mutations in human lamin A and associated proteins were found to cause a large number of diseases, termed 'laminopathies.' These diseases include muscular dystrophies, lipodystrophies, neuropathies, and premature aging syndromes. Despite the growing number of studies on lamins and their associated proteins, the molecular organization of lamins in health and disease is still elusive. Likewise, there is no comprehensive view how mutations in lamins result in a plethora of diseases, selectively affecting different tissues. Here, we discuss some of the structural aspects of lamins and the nuclear lamina organization, in light of recent results

Ladderane skeleton approach by multiple [2+2] photocycloaddition

Ces travaux de thèse ont pour but de synthétiser des squelettes ladderanes en une seule étape de photocycloaddition [2+2] multiple. Le produit naturel acide pentacycloanammoxique est la molécule visée au terme de ce projet. Dans une première partie, nous avons développé une méthode originale de photocycloaddition [2+2] intramoléculaire à partir de précurseurs polyéniques soufrés. Ainsi, quatre types de composés cycliques ont été obtenus et caractérisés. Cette méthodologie a été appliquée à des composés mono, di et triènes, sulfures et sulfone, par irradiation au sein d’un photoréacteur Rayonet, ou dans des conditions plus douces avec des LED bleues. Différentes stratégies ont été testées dans le but de former des ladderanes, comme la modification des extrémités des chaînes polyéniques, les catalyses au cuivre (I) et photoredox, ou encore la photosensibilisation, mais aucune n’a permis la formation de plus d’un cyclobutane. La technique de l’encapsulation supramoléculaire au sein de cavités cyclodextrines et cucurbituriles a permis de préparer quantitativement un composé cyclobutanique de configuration syn-trans-syn sur petite échelle. Ce résultat étudié en photochimie de flux, représente une perspective encourageante pour la synthèse de ladderanes. Nous avons également étudié la synthèse d’un modèle de métabolite de l’acide pentacycloanammoxique, qui représenterait un étalon analytique. Dans ce contexte, une cétone tricyclique a été dans un premier temps préparée en sept étapes avec un rendement de 67% par le biais de la cycloisomérisation catalysée au platine (II) d’un précurseur énynylester. Puis l’intermédiaire alcool le plus avancé de la synthèse a été obtenu après six étapes supplémentaires avec un rendement de 7,4%. Enfin, une méthodologie de synthèse a été développée autour de l’intermédiaire cétone tricyclique de structure originale, permettant des transformations hautement régio et diastéréosélectives. Des réactions d’additions nucléophiles ou d’extensions de cycles telles que l’homologation de Bayer-Villiger ou le réarrangement de Beckmann ont été étudiées.The aim of this PhD work was to synthesize ladderane skeletons in one multiple [2+2] photocycloaddition step. The natural product pentacycloanammoxic acid is the target molecule of the project. In a first part, we developped an original method of intramolecular [2+2] photocycloaddition from sulfide polyenic precursors. Thus, four kind of cyclic compounds were obtained and characterized. This metodology has been applied to mono, di, and triene compounds, either sulfide or sulfone, by irradiation in a Rayonet photoreactor or in milder conditions with blue LEDs. Different strategies have been tested in order to create ladderanes, such as modification of polyene chain end, copper(I) and photoredox catalysis, or photosensitization, but none allowed the formation of more than one cyclobutane. Supramolecular encapsulation in cyclodextrins and cucurbiturils have provided quantitatively cyclobutane compound with syn-trans-syn configuration on small scale. This result studied in flow photochemistry is an encouraging perspective for ladderane preparation. We have also studied the synthesis of a pentacycloanammoxic acid metabolite model. In this context, a tricyclic ketone has been prepared first in seven steps with a gobal yield of 67%, based on a platinum(II) catalysed cycloisomerization as a key step. Then, the most advanced alcohol intermediaite has been obtained after six more steps in a 7.4% yield. Finally, a synthesis methodology has been developped around the tricyclic ketone intermediaite, of novel structure, allowing highly regio and diastereoselective transformations. Nucleophilic additions or ring expansion reactions such as Bayer-Villiger homologation or Beckmann rearrangement have been studied

Approche des squelettes ladderanes par photocycloaddition [2+2] multiples

The aim of this PhD work was to synthesize ladderane skeletons in one multiple [2+2] photocycloaddition step. The natural product pentacycloanammoxic acid is the target molecule of the project. In a first part, we developped an original method of intramolecular [2+2] photocycloaddition from sulfide polyenic precursors. Thus, four kind of cyclic compounds were obtained and characterized. This metodology has been applied to mono, di, and triene compounds, either sulfide or sulfone, by irradiation in a Rayonet photoreactor or in milder conditions with blue LEDs. Different strategies have been tested in order to create ladderanes, such as modification of polyene chain end, copper(I) and photoredox catalysis, or photosensitization, but none allowed the formation of more than one cyclobutane. Supramolecular encapsulation in cyclodextrins and cucurbiturils have provided quantitatively cyclobutane compound with syn-trans-syn configuration on small scale. This result studied in flow photochemistry is an encouraging perspective for ladderane preparation. We have also studied the synthesis of a pentacycloanammoxic acid metabolite model. In this context, a tricyclic ketone has been prepared first in seven steps with a gobal yield of 67%, based on a platinum(II) catalysed cycloisomerization as a key step. Then, the most advanced alcohol intermediaite has been obtained after six more steps in a 7.4% yield. Finally, a synthesis methodology has been developped around the tricyclic ketone intermediaite, of novel structure, allowing highly regio and diastereoselective transformations. Nucleophilic additions or ring expansion reactions such as Bayer-Villiger homologation or Beckmann rearrangement have been studied.Ces travaux de thèse ont pour but de synthétiser des squelettes ladderanes en une seule étape de photocycloaddition [2+2] multiple. Le produit naturel acide pentacycloanammoxique est la molécule visée au terme de ce projet. Dans une première partie, nous avons développé une méthode originale de photocycloaddition [2+2] intramoléculaire à partir de précurseurs polyéniques soufrés. Ainsi, quatre types de composés cycliques ont été obtenus et caractérisés. Cette méthodologie a été appliquée à des composés mono, di et triènes, sulfures et sulfone, par irradiation au sein d’un photoréacteur Rayonet, ou dans des conditions plus douces avec des LED bleues. Différentes stratégies ont été testées dans le but de former des ladderanes, comme la modification des extrémités des chaînes polyéniques, les catalyses au cuivre (I) et photoredox, ou encore la photosensibilisation, mais aucune n’a permis la formation de plus d’un cyclobutane. La technique de l’encapsulation supramoléculaire au sein de cavités cyclodextrines et cucurbituriles a permis de préparer quantitativement un composé cyclobutanique de configuration syn-trans-syn sur petite échelle. Ce résultat étudié en photochimie de flux, représente une perspective encourageante pour la synthèse de ladderanes. Nous avons également étudié la synthèse d’un modèle de métabolite de l’acide pentacycloanammoxique, qui représenterait un étalon analytique. Dans ce contexte, une cétone tricyclique a été dans un premier temps préparée en sept étapes avec un rendement de 67% par le biais de la cycloisomérisation catalysée au platine (II) d’un précurseur énynylester. Puis l’intermédiaire alcool le plus avancé de la synthèse a été obtenu après six étapes supplémentaires avec un rendement de 7,4%. Enfin, une méthodologie de synthèse a été développée autour de l’intermédiaire cétone tricyclique de structure originale, permettant des transformations hautement régio et diastéréosélectives. Des réactions d’additions nucléophiles ou d’extensions de cycles telles que l’homologation de Bayer-Villiger ou le réarrangement de Beckmann ont été étudiées

From Enynyl Esters to Functionalized Polycyclic Derivatives via Cycloisomerization and Post-Functionalization

International audienceThe post-functionalization of ketone products originating from the PtCl2-catalyzed cycloisomerization of enynyl esters is described. Postfunctionalization has been accomplished via diastereoselective alkylation, regioselective cyclopropane opening and regioselective Baeyer Villiger and Beckmann rearrangements to provide functionalized polycycles