Design and synthesis of an androgen receptor pure antagonist (CH5137291) for the treatment of castration-resistant prostate cancer

A series of 5,5-dimethylthiohydantoin derivatives were synthesized and evaluated for androgen receptor pure antagonistic activities for the treatment of castration-resistant prostate cancer. Since CH4933468, which we reported previously, had a problem with agonist metabolites, novel thiohydantoin derivatives were identified by applying two strategies. One was the replacement of the alkylsulfonamide moiety by a phenylsulfonamide to avoid the production of agonist metabolites. The other was the replacement of the phenyl ring with a pyridine ring to improve in vivo potency and reduce hERG affinity. Pharmacological assays indicated that CH5137291 (17b) was a potent AR pure antagonist which did not produce the agonist metabolite. Moreover, CH5137291 completely inhibited in vivo tumor growth of LNCaP-BC2, a castration-resistant prostate cancer model.     

Random walk in genome space: A key ingredient of intermittent dynamics of community assembly on evolutionary time scales

Community assembly is studied using individual-based multispecies models. The models have stochastic population dynamics with mutation, migration, and extinction of species. Mutants appear as a result of mutation of the resident species, while migrants have no correlation with the resident species. It is found that the dynamics of community assembly with mutations are quite different from the case with migrations. In contrast to mutation models, which show intermittent dynamics of quasi-steady states interrupted by sudden reorganizations of the community, migration models show smooth and gradual renewal of the community. As a consequence, instead of the 1/f diversity fluctuations found for the mutation models, 1/f², random-walk like fluctuations are observed for the migration models. In addition, a characteristic species-lifetime distribution is found: a power law that is cut off by a “skewed” distribution in the long-lifetime regime. The latter has a longer tail than a simple exponential function, which indicates an age-dependent species-mortality function. Since this characteristic profile has been observed, both in fossil data and in several other mathematical models, we conclude that it is a universal feature of macroevolution.     

Structural Evidence of Glycoprotein Assembly in Cellular Membrane Compartments prior to Alphavirus Budding

Membrane glycoproteins of alphavirus play a critical role in the assembly and budding of progeny virions. However, knowledge regarding transport of viral glycoproteins to the plasma membrane is obscure. In this study, we investigated the role of cytopathic vacuole type II (CPV-II) through in situ electron tomography of alphavirus-infected cells. The results revealed that CPV-II contains viral glycoproteins arranged in helical tubular arrays resembling the basic organization of glycoprotein trimers on the envelope of the mature virions. The location of CPV-II adjacent to the site of viral budding suggests a model for the transport of structural components to the site of budding. Thus, the structural characteristics of CPV-II can be used in evaluating the design of a packaging cell line for replicon production.Semliki Forest virus (SFV) is an enveloped alphavirus belonging to the family Togaviridae. This T=4 icosahedral virus particle is approximately 70 nm in diameter (30) and consists of 240 copies of E1/E2 glycoprotein dimers (3, 8, 24). The glycoproteins are anchored in a host-derived lipid envelope that encloses a nucleocapsid, made of a matching number of capsid proteins and a positive single-stranded RNA molecule. After entry of the virus via receptor-mediated endocytosis, a low-pH-induced fusion of the viral envelope with the endosomal membrane delivers the nucleocapsid into the cytoplasm, where the replication events of SFV occur (8, 19, 30). Replication of the viral genome and subsequent translation into structural and nonstructural proteins followed by assembly of the structural proteins and genome (7) lead to budding of progeny virions at the plasma membrane (18, 20). The synthesis of viral proteins shuts off host cell macromolecule synthesis, which allows for efficient intracellular replication of progeny virus (7). The expression of viral proteins leads to the formation of cytopathic vacuolar compartments as the result of the reorganization of cellular membrane in the cytoplasm of an infected cell (1, 7, 14).Early studies using electron microscopy (EM) have characterized the cytopathic vacuoles (CPVs) in SFV-infected cells (6, 13, 14) and identified two types of CPV, namely, CPV type I (CPV-I) and CPV-II. It was found that CPV-I is derived from modified endosomes and lysosomes (18), while CPV-II is derived from the trans-Golgi network (TGN) (10, 11). Significantly, the TGN and CPV-II vesicles are the major membrane compartments marked with E1/E2 glycoproteins (9, 11, 12). Inhibition by monensin results in the accumulation of E1/E2 glycoproteins in the TGN (12, 26), thereby indicating the origin of CPV-II. While CPV-II is identified as the predominant vacuolar structure at the late stage of SFV infection, the exact function of this particular cytopathic vacuole is less well characterized than that of CPV-I (2, 18), although previous observations have pointed to the involvement of CPV-II in budding, because an associated loss of viral budding was observed when CPV-II was absent (9, 36).In this study, we characterized the structure and composition of CPV-II in SFV-infected cells in situ with the aid of electron tomography and immuno-electron microscopy after physical fixation of SFV-infected cells by high-pressure freezing and freeze substitution (21, 22, 33). The results revealed a helical array of E1/E2 glycoproteins within CPV-II and indicate that CPV-II plays an important role in intracellular transport of glycoproteins prior to SFV budding.     

Novel method to observe subtle structural modulation of stratum corneum on applying chemical agents

In the development of functional chemicals such as percutaneous penetration enhancers and cosmetics, the structural evidence at the molecular level in stratum corneum (SC) is highly desirable. We developed a method to observe a minute structural change of intercellular lipid matrix and corneocytes on applying the chemicals to the SC using synchrotron X-ray diffraction technique. The performance of the present method was demonstrated by applying typical chemicals, chloroform/methanol mixture, hydrophilic ethanol and hydrophobic d-limonene. From the small- and wide-angle X-ray diffraction we obtained the following results: on applying chloroform/methanol mixture the intercellular lipids were extracted markedly, on applying ethanol the intercellular lipid structure was slightly disrupted, ethanol molecules were taken into the corneocytes and in addition the pools of ethanol seem to be formed in the hydrophilic region of the intercellular lipid matrix in the SC, and on applying d-limonene the repeat distance of the long lamellar structure increased by incorporating d-limonene molecules, the intercellular lipid structure was slightly disrupted, and the pools of d-limonene were formed in the hydrophobic region of the intercellular lipid matrix in the SC.     

Possible mechanism of adenovirus generation from a cloned viral genome tagged with nucleotides at its ends

The entire cloned human adenovirus type 5 (Ad5) genome is known to be able to generate infectious virus after transfection into 293 cells when the both ends of the genome are exposed by digestion with appropriate restriction enzymes. However, when one or both ends of the genome are tagged with nucleotides and are not intact, whether the tagged end of the viral genome was remained tagged or corrected to be intact during the generation of viral clones has been unclear and, if such oligonucleotide removal occurs, how does the virus remove these tagged sequences and thereby restore its proper structure? Here, we show in our semi‐quantitative study that the generation efficiency of virus clones decreases depending on the length of nucleotide tags at the both ends and that both the oligonucleotide tags were precisely removed during virus generation with restoration of the proper terminal sequences. Interestingly the viral genome of which one end was tagged, while the other was attached about 12‐kb sequences, did generate intact viral clones at a reduced but significant efficiency. From these results, we here propose a possible mechanism whereby the terminal‐protein‐deoxycytidine complex enters from the enzyme‐cleaved end and reaches deoxyguanine at the initiating position of DNA synthesis in vivo. A replication origin at one end, embedded deeply in double‐stranded DNA, can be activated by two cycles of one‐directional full‐length DNA synthesis initiated by the other exposed replication origin about 30 kilobases away. We also describe new cassette cosmids which can use not only PacI but also BstBI for construction of an adenovirus vector, without reducing construction efficiency.     

Synthesis and anti-juvenile hormone activity of ethyl 4-(2-aryloxyhexyloxy)benzoates

A series of ethyl 4-(2-aryloxyhexyloxy)benzoates was prepared and tested for their activity to induce precocious metamorphosis in larvae of the silkworm. Phenyl analog 5 showed activity comparable to that of the 6-methyl-3-pyridyl analog reported as a novel anti-JH agent. The activity of 5 could be fully counteracted by methoprene, a JH agonist. The ethoxycarbonyl group of 5 was essential for its activity.     

Impact of protists on the activity and structure of the bacterial community in a rice field soil

Flooded rice fields have become a model system for the study of soil microbial ecology. In Italian rice fields, in particular, aspects from biogeochemistry to molecular ecology have been studied, but the impact of protistan grazing on the structure and function of the prokaryotic community has not been examined yet. We compared an untreated control soil with a gamma-radiation-sterilized soil that had been reinoculated with a natural bacterial assemblage. In order to verify that the observed effects were due to protistan grazing and did not result from sterilization, we set up a third set of microcosms containing sterilized soil that had been reinoculated with natural assemblage bacteria plus protists. The spatial and temporal changes in the protistan and prokaryotic communities were examined by denaturing gradient gel electrophoresis (DGGE) and terminal restriction fragment length polymorphism (T-RFLP) analysis, respectively, both based on the small-subunit gene. Sequences retrieved from DGGE bands were preferentially affiliated with Cercozoa and other bacteriovorous flagellates. Without protists, the level of total DNA increased with incubation time, indicating that the level of the microbial biomass was elevated. Betaproteobacteria were preferentially preyed upon, while low-G + C-content gram-positive bacteria became more dominant under grazing pressure. The bacterial diversity detectable by T-RFLP analysis was greater in the presence of protists. The level of extractable NH4+ was lower and the level of extractable SO4(2-) was higher without protists, indicating that nitrogen mineralization and SO4(2-) reduction were stimulated by protists. Most of these effects were more obvious in the partially oxic surface layer (0 to 3 mm), but they could also be detected in the anoxic subsurface layer (10 to 13 mm). Our observations fit well into the overall framework developed for protistan grazing, but with some modifications pertinent to the wetland situation: O2 was a major control, and O2 availability may have limited directly and indirectly the development of protists. Although detectable in the lower anoxic layer, grazing effects were much more obvious in the partially oxic surface layer.     

Identification of 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD)-inducible genes in human amniotic epithelial cells

Background  

Exposure to dioxins results in a broad range of pathophysiological disorders in human fetuses. In order to evaluate the effects of dioxins on the feto-placental tissues, we analyzed the gene expression in 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) treated primary cultures of human amniotic epithelial cells.     

Self-renewal and lineage restriction of hematopoietic stem cells

Over the past decade, the purification and characterization of hematopoietic stem cells have ascertained their presence at the clonal level although they had hitherto existed conceptually. Now we have begun to understand their functions in molecular terms. Several important works indicative of such a new era in stem cell biology have been published recently. In particular, Bmi1, which belongs to the Polycomb group of genes, has been implicated as one of the basic molecules to maintain the proliferation capacity in hematopoietic stem cells. We need to seek other similarly important molecules for their functions. Perhaps studying interactions among genes is one of the most exciting subjects in stem cell research.