Artificial analogs of naturally occurring tumor promoters as biochemical tools and therapeutic leads.

Tumor promoters are non-carcinogenic chemicals that enhance tumor formation when administered repeatedly after a low dose of a carcinogen. Phorbol esters, teleocidins, and aplysiatoxins are typical examples of naturally occurring tumor promoters. All of them share the ability to bind and activate protein kinase C (PKC) despite the differences in their chemical structures.

Anionic polymerization mechanism of acrylonitrile trimer anions: key branching point between cyclization and chain propagation.

A cluster anion of vinyl compounds in the gaseous phase has served as one of the simplest microscopic models of the initial stages of anionic polymerization. Herein, we describe our investigations into the initial stage mechanisms of anionic polymerization of acrylonitrile (AN; CH2═CHCN) trimer anions. While the cyclic oligomer is found in mass and photoelectron spectroscopic studies of (AN)3(-), only the chain oligomer is found in the infrared photodissociation (IRPD) spectrum of Ar-tagged (AN)3(-).

Acetylation regulates subcellular localization of eukaryotic translation initiation factor 5A (eIF5A).

Eukaryotic translation initiation factor 5A (eIF5A) is a protein subject to hypusination, which is essential for its function. eIF5A is also acetylated, but the role of that modification is unknown. Here, we report that acetylation regulates the subcellular localization of eIF5A.

Nuclear pore dynamics during the cell cycle.

A nuclear pore complex (NPC) is a large protein assembly that mediates the nucleocytoplasmic exchange of molecules. During the cell cycle, NPCs assemble, disassemble, and dynamically change their distribution on assembled nuclear envelope (NE), whereas in post-mitosis, NPCs are extremely stable. Extensive studies on its components, structure, and building blocks allow the study of its assembly and disassembly at the molecular level.

Nanoscale shuffling in a template-assisted self-assembly of binary colloidal particles.

We have fabricated a square lattice array of sub-micrometer fluorescent (red and green) polystyrene particles. The particles were each embedded into small pits fabricated on a silicon substrate by electron beam lithography, through the drying process of an aqueous suspension containing equal amounts of the two species. We indexed 0 and 1 for each red and green particle, respectively, and then obtained a one-dimensional bit sequence by the successive reading of the indices in a predetermined manner.

Design and synthesis of binding growth factors.

Growth factors play important roles in tissue regeneration. However, because of their instability and diffusible nature, improvements in their performance would be desirable for therapeutic applications. Conferring binding affinities would be one way to improve their applicability.

Visualizing specific protein glycoforms by transmembrane fluorescence resonance energy transfer.

Analyses of mice lacking glycosyltransferase have suggested that their pathological phenotypes are not attributable to the overall change of the sugar modification, but instead the result of changes of the glycan structures on a specific 'target' glycoprotein. Therefore, detecting or monitoring the glycosylation status of a specific protein in living cells is important, but no such methods are currently available. Here we demonstrate the detection of glycoforms of a specific glycoprotein using the fluorescence resonance energy transfer technique.

Remarkable effects of terminal groups and solvents on helical folding of o-phenylene oligomers.

Although o-phenylene oligomers (OP(n)R) made of dimethoxyphenylene units are thought to be intrinsically dynamic due to π-electronic repulsion, we show that they fold into a regular helical geometry in CH(3)CN when they carry terminal groups such as CH(3), CH(2)OH, Br, CO(2)Bn, and NO(2). We evaluated their helical inversion kinetics via optical resolution of long-chain oligomers (e.g.

Kinetically controlled one-pot formation of DEFGH-rings of type B physalins through domino-type transformations.

The characteristic DEFGH-ring system of type B physalins has been synthesized by means of a one-pot procedure incorporating domino-type ring transformations. Unexpectedly, we found that introduction of an α-hydroxyester functionality at C17 in ring E allowed the key 7-endo oxy-Michael reaction to proceed. Originally this was thought to be an unfavored process.

Identification of compounds that augment the lectin-sensitivity of Chinese Hamster Ovary cells.

Glycosylation is now recognized as one of the most important modifications of eukaryotic proteins. In cancer biology, alterations in cell surface glycosylation have been exploited as valuable biomarkers, and the relationship of this modification to the metastatic characteristics of cancer cells has also been well-documented. Chemicals that can alter cell surface glycosylation patterns will therefore become attractive lead compounds for controlling the metastatic characteristics of cancer cells, one of the critical factors in their malignancy and prognosis of the disease.

Temperature-dependent magnetotransport around ν=1/2 in ZnO heterostructures.

The sequence of prominent fractional quantum Hall states up to ν=5/11 around ν=1/2 in a high-mobility two-dimensional electron system confined at oxide heterointerface (ZnO) is analyzed in terms of the composite fermion model. The temperature dependence of R(xx) oscillations around ν=1/2 yields an estimation of the composite fermion effective mass, which increases linearly with the magnetic field. This mass is of similar value to an enhanced electron effective mass, which in itself arises from strong electron interaction.

Tunable, dynamic and electrically stimulated lectin-carbohydrate recognition on a glycan-grafted conjugated polymer.

An electroactive platform for multivalent, reversible and electrically stimulated lectin-carbohydrate recognition based on mannose-functionalized conjugated polymer is reported and tuned by electrocopolymerization of mixture of tri(ethylene glycol)-functionalized EDOT and its α-mannose conjugate.

A plant peptide: N-glycanase orthologue facilitates glycoprotein ER-associated degradation in yeast.

Background: The cytoplasmic peptide:N-glycanase (PNGase) is a deglycosylating enzyme involved in the ER-associated degradation (ERAD) process, while ERAD-independent activities are also reported. Previous biochemical analyses indicated that the cytoplasmic PNGase orthologue in Arabidopsis thaliana (AtPNG1) can function as not only PNGase but also transglutaminase, while its in vivo function remained unclarified.

Methods: AtPNG1 was expressed in Saccharomyces cerevisiae and its in vivo role on PNGase-dependent ERAD pathway was examined.

Establishment of Sf9 Transformants Constitutively Expressing PBAN Receptor Variants: Application to Functional Evaluation.

To facilitate further evaluation of pheromone biosynthesis activating neuropeptide receptor (PBANR) functionality and regulation, we generated cultured insect cell lines constitutively expressing green fluorescent protein chimeras of the recently identified Bombyx mori PBANR (BommoPBANR) and Pseudaletia separata PBANR (PsesePBANR) variants. Fluorescent chimeras included the BommoPBANR-A, -B, and -C variants and the PsesePBANR-B and -C variants. Cell lines expressing non-chimeric BommoPBANR-B and -C variants were also generated.

Re-Evaluation of the PBAN Receptor Molecule: Characterization of PBANR Variants Expressed in the Pheromone Glands of Moths.

Sex pheromone production in most moths is initiated following pheromone biosynthesis activating neuropeptide receptor (PBANR) activation. PBANR was initially cloned from pheromone glands (PGs) of Helicoverpa zea and Bombyx mori. The B.

Construction of an in vivo system for functional analysis of the genes involved in sex pheromone production in the silkmoth, Bombyx mori.

Moths produce species-specific sex pheromones to attract conspecific mates. The biochemical processes that comprise sex pheromone biosynthesis are precisely regulated and a number of gene products are involved in this biosynthesis and regulation. In recent years, at least 300 EST clones have been isolated from Bombyx mori pheromone gland (PG) specific cDNA libraries with some of those clones [i.

Ligand field effect at oxide-metal interface on the chemical reactivity of ultrathin oxide film surface.

Ultrathin oxide film is currently one of the paramount candidates for a heterogeneous catalyst because it provides an additional dimension, i.e., film thickness, to control chemical reactivity.

Estimation of binding constants of peptide nucleic acid and secondary-structured DNA by affinity capillary electrophoresis.

An affinity capillary electrophoresis method was developed to determine a binding constant between a peptide nucleic acid (PNA) and a hairpin-structured DNA. A diblock copolymer composed of PNA and polyethylene glycol (PEG) was synthesized as a novel affinity probe. The base sequence of the probe's PNA segment was complementary to a hairpin-structured region of a 60-base single-stranded DNA (ssDNA).

Magnetic stripes and skyrmions with helicity reversals.

It was recently realized that topological spin textures do not merely have mathematical beauty but can also give rise to unique functionalities of magnetic materials. An example is the skyrmion--a nano-sized bundle of noncoplanar spins--that by virtue of its nontrivial topology acts as a flux of magnetic field on spin-polarized electrons. Lorentz transmission electron microscopy recently emerged as a powerful tool for direct visualization of skyrmions in noncentrosymmetric helimagnets.

Structure formation and catalytic activity of DNA dissolved in organic solvents.

Equal-opportunity dissolver: By attaching polyethylene glycol at its 5' end, DNA (PEG-DNA) can be solubilized in various organic solvents and was shown to form G-quadruplexes by CD spectroscopy. A complex containing iron(III) protoporphyrin IX (hemin) and G-quadruplex-forming PEG-DNA catalyzed an oxidative reaction in methanol (see scheme).

PRMT1 is required for RAP55 to localize to processing bodies.

In eukaryotic cells, components of messenger ribonucleoproteins (mRNPs) are often detected in cytoplasmic granules, such as processing bodies (P-bodies) and stress granules (SGs) where translationally repressed mRNAs accumulate. RAP55A, which is an RNA binding component of mRNPs, acts as a translational repressor and localizes to P-bodies and SGs. We found here that a homologous protein RAP55B also localized to P-bodies when expressed in human cultured cells.

Ligand effects on the stability of thiol-stabilized gold nanoclusters: Au25(SR)18(-), Au38(SR)24, and Au102(SR)44.

We have studied the electrochemical and thermodynamic stability of Au(25)(SR)(18)(-), Au(38)(SR)(24), and Au(102)(SR)(44), R = CH(3), C(6)H(13), CH(2)CH(2)Ph, Ph, PhF, and PhCOOH, in order to examine ligand effects on the stability of thiol-stabilized gold nanoclusters, Au(m)(SR)(n). Aliphatic thiols, in general, have higher electrochemical and thermodynamic stability than aromatic thiols, and the -SCH(2)CH(2)Ph thiol is particularly appealing because of its high electrochemical and thermodynamic stability. The stabilization of Au(m) by nSR for Au(m)(SR)(n) can be rationalized by the stabilization of an Au atom by an SR for the simple molecule AuSR, regardless of interligand interaction and system size and shape.

Limonoid compounds inhibit sphingomyelin biosynthesis by preventing CERT protein-dependent extraction of ceramides from the endoplasmic reticulum.

To identify novel inhibitors of sphingomyelin (SM) metabolism, a new and selective high throughput microscopy-based screening based on the toxicity of the SM-specific toxin, lysenin, was developed. Out of a library of 2011 natural compounds, the limonoid, 3-chloro-8β-hydroxycarapin-3,8-hemiacetal (CHC), rendered cells resistant to lysenin by decreasing cell surface SM. CHC treatment selectively inhibited the de novo biosynthesis of SM without affecting glycolipid and glycerophospholipid biosynthesis.

Protuboxepin A, a marine fungal metabolite, inducing metaphase arrest and chromosomal misalignment in tumor cells.

Previously we reported the identification of a new oxepin-containing diketopiperazine-type marine fungal metabolite, named protuboxepin A which showed antiproliferative activity in several cancer cell lines. In this study we elucidated the mechanism by which protuboxepin A induces cancer cell growth inhibition. Here we report that protuboxepin A induced round-up morphology, M phase arrest, and an increase in the subG(1) population in tumor cells in a dose dependent manner.