Cobalt hematoporphyrin inhibits CLEC-2-podoplanin interaction, tumor metastasis, and arterial/venous thrombosis in mice.

The platelet activation receptor C-type lectin-like receptor 2 (CLEC-2) interacts with podoplanin on the surface of certain types of tumor cells, and this interaction facilitates tumor metastasis. CLEC-2 is also involved in thrombus formation and its stabilization. Because CLEC-2-depleted mice are protected from experimental lung metastasis and thrombus formation and do not show increased bleeding time, CLEC-2 may serve as a good target for antimetastatic or antithrombotic drugs.

A novel partial agonist of GPBA reduces blood glucose level in a murine glucose tolerance test.

GPBA is a G protein-coupled receptor that is activated by bile acids. Because activation of GPBA leads to increased cAMP levels and secretion of incretins and insulin, GPBA has been proposed as a promising drug target for the treatment of metabolic syndrome. Previously, we have developed a ligand-screening system to identify novel agonists of GPBA by means of a fusion protein of GPBA with G protein stimulatory α subunit (Gsα) and by a [S]GTPγS-binding assay.

Screening of a virtual mirror-image library of natural products.

We established a facile access to an unexplored mirror-image library of chiral natural product derivatives using d-protein technology. In this process, two chemical syntheses of mirror-image substances including a target protein and hit compound(s) allow the lead discovery from a virtual mirror-image library without the synthesis of numerous mirror-image compounds.

Identification and molecular docking studies for novel inverse agonists of SREB, super conserved receptor expressed in brain.

The identification of novel synthetic ligands for G protein-coupled receptors (GPCRs) is important not only for understanding human physiology, but also for the development of novel drugs, especially for orphan GPCRs for which endogenous ligands are unknown. One of the orphan GPCR subfamilies, Super conserved Receptor Expressed in Brain (SREB), consists of GPR27, GPR85 and GPR173 and is expressed in the central nervous system. We report herein the identification of inverse agonists for the SREB family without their agonists.

Potential Role of the Formation of Tunneling Nanotubes in HIV-1 Spread in Macrophages.

Tunneling nanotubes (TNTs), the long membrane extensions connecting distant cells, have emerged as a novel form of cell-to-cell communication. However, it is not fully understood how and to what extent TNTs contribute to intercellular spread of pathogens including HIV-1. In this study, we show that HIV-1 promotes TNT formation per se via its protein Nef and a cellular protein M-Sec, which appears to mediate approximately half of viral spread among monocyte-derived macrophages (MDMs).

Radioprotective activity of Polyalthia longifolia standardized extract against X-ray radiation injury in mice.

The radioprotective effect of Polyalthia longifolia was studied in mice. P. longifolia treatment showed improvement in mice survival compared to 100% mortality in the irradiated mice.

In vivo and in vitro evaluation of novel μ-opioid receptor agonist compounds.

Opioids are the most effective and widely used drugs for pain treatment. Morphine is an archetypal opioid and is an opioid receptor agonist. Unfortunately, the clinical usefulness of morphine is limited by adverse effects such as analgesic tolerance and addiction.

Evaluation of the cytotoxicity, cell-cycle arrest, and apoptotic induction by Euphorbia hirta in MCF-7 breast cancer cells.

Context: Euphorbia hirta L. (Euphorbiaceae) has been used as a folk remedy in Southeast Asia for the treatment of various ailments.

Objective: The current study evaluates the cytotoxicity, cell-cycle arrest, and apoptotic induction by E.

Dissection of two modes of IE1 sub-nuclear localization in baculovirus-infected cells.

Prior to viral DNA replication, baculovirus IE1 exhibits a focal distribution within the cell nucleus. During DNA replication, the IE1 foci apparently expand and develop into a virus replication center called the virogenic stroma (VS). In our search for chemical compounds capable of modulating Bombyx mori nucleopolyhedrovirus (BmNPV: a prototype of baculovirus) replication, we found an inhibitor (dBIQdO) of IE1 focus formation.

Spectomycin B1 as a novel SUMOylation inhibitor that directly binds to SUMO E2.

Conjugation of small ubiquitin-like modifier (SUMO) to protein (SUMOylation) regulates multiple biological systems by changing the functions and fates of a large number of proteins. Consequently, abnormalities in SUMOylation have been linked to multiple diseases, including breast cancer. Using an in situ cell-based screening system, we have identified spectomycin B1 and related natural products as novel SUMOylation inhibitors.

Identification and characterization of an inhibitor of trichothecene 3-O-acetyltransferase, TRI101, by the chemical array approach.

Trichothecene 3-O-acetyltransferase (TRI101) is an indispensable enzyme for the biosynthesis of trichothecenes, a group of mycotoxins produced by Fusarium graminearum. In this study, an inhibitor of TRI101 was identified by chemical array analysis using compounds from the RIKEN Natural Products Depository (NPDepo) library. Although the addition of the identified enzyme inhibitor to the fungal culture did not inhibit trichothecene production, it can serve as a candidate lead compound in the development of a mycotoxin inhibitor that inactivates fungal defense mechanisms.

Affinity-based screening of MDM2/MDMX-p53 interaction inhibitors by chemical array: identification of novel peptidic inhibitors.

MDM2 and MDMX are oncoproteins that negatively regulate the activity and stability of the tumor suppressor protein p53. The inhibitors of protein-protein interactions (PPIs) of MDM2-p53 and MDMX-p53 represent potential anticancer agents. In this study, a novel approach for identifying MDM2-p53 and MDMX-p53 PPI inhibitor candidates by affinity-based screening using a chemical array has been established.

Sulfonamides identified as plant immune-priming compounds in high-throughput chemical screening increase disease resistance in Arabidopsis thaliana.

Plant activators are agrochemicals that protect crops from diseases by activating the plant immune system. To isolate lead compounds for use as practical plant activators, we screened two different chemical libraries composed of various bioactive substances by using an established screening procedure that can selectively identify immune-priming compounds. We identified and characterized a group of sulfonamide compounds - sulfameter, sulfamethoxypyridazine, sulfabenzamide, and sulfachloropyridazine - among the various isolated candidate molecules.

Indomethacin induction of metamorphosis from the asexual stage to sexual stage in the moon jellyfish, Aurelia aurita.

We found while screening a chemical library that indomethacin, an inhibitor of prostaglandin biosynthesis, induced strobilation (metamorphosis from the asexual to sexual stage) in the moon jellyfish, Aurelia aurita. Indomethacin initiated strobilation in a dose-dependent manner, but was not involved in the progression of strobilation. Pharmacological experiments suggested that indomethacin could induce strobilation independently of prostaglandin biosynthesis.

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.

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.

Construction of a microbial natural product library for chemical biology studies.

The RIKEN Natural Products Depository (NPDepo) is a public depository of small molecules. Currently, the NPDepo chemical library contains 39,200 pure compounds, half of which are natural products and their derivatives. In order to reinforce the uniqueness of our chemical library, we have improved our strategies for the collection of microbial natural products.

Spirotoamides A and B, novel 6,6-spiroacetal polyketides isolated from a microbial metabolite fraction library.

Two new 6,6-spiroacetal polyketides, spirotoamides A (1) and B (2), were isolated from a microbial metabolite fraction library of Streptomyces griseochromogenes JC82-1223 by screening of structurally unique compounds based on a search of spectral database. The fraction library was constructed using a systematic separation method to efficiently discover new metabolites from microbial sources such as actinomycetes and fungi. The structures of 1 and 2 were elucidated by 2D-NMR and mass spectrometric measurements.

Fluorescence image screening for chemical compounds modifying cholesterol metabolism and distribution.

An automated fluorescence microscopy assay using a nontoxic cholesterol binding protein, toxin domain 4, (D4), was developed in order to identify chemical compounds modifying intracellular cholesterol metabolism and distribution. Using this method, we screened a library of 1,056 compounds and identified 35 compounds that decreased D4 binding to the cell surface. Among them, 8 compounds were already reported to alter the biosynthesis or the intracellular distribution of cholesterol.

Fusarisetin A, an acinar morphogenesis inhibitor from a soil fungus, Fusarium sp. FN080326.

An acinar morphogenesis inhibitor named fusarisetin A (1) that possesses both an unprecedented carbon skeleton and a new pentacyclic ring system has been identified from an in-house fractionated fungal library using a three-dimensional matrigel-induced acinar morphogenesis assay system. The structure of 1 was determined in detail by NMR and circular dichroism spectroscopy, X-ray analysis, and chemical reaction experiments.

Cobtorin target analysis reveals that pectin functions in the deposition of cellulose microfibrils in parallel with cortical microtubules.

Cellulose and pectin are major components of primary cell walls in plants, and it is believed that their mechanical properties are important for cell morphogenesis. It has been hypothesized that cortical microtubules guide the movement of cellulose microfibril synthase in a direction parallel with the microtubules, but the mechanism by which this alignment occurs remains unclear. We have previously identified cobtorin as an inhibitor that perturbs the parallel relationship between cortical microtubules and nascent cellulose microfibrils.

Verticilactam, a new macrolactam isolated from a microbial metabolite fraction library.

Systematic isolation of microbial metabolites has been performed to construct microbial metabolite libraries or fraction libraries. A novel macrolactam, verticilactam (1), was isolated from a library of Streptomyces spiroverticillatus JC-8444. The structure was determined on the basis of NMR and mass spectrometric measurements.

A novel yeast cell-based screen identifies flavone as a tankyrase inhibitor.

The telomere-associated protein tankyrase 1 is a poly(ADP-ribose) polymerase and is considered to be a promising target for cancer therapy, especially for BRCA-associated cancers. However, an efficient assay system for inhibitor screening has not been established, mainly due to the difficulty of efficient preparation of the enzyme and its substrate. Here, we report a cell-based assay system for detecting inhibitory activity against tankyrase 1.

Synthesis and anti-angiogenic activity of cortistatin analogs.

Analogs of cortistatins, a series of anti-angiogenic compounds isolated from the Indonesian marine sponge Cortisium simplex, were synthesized from estrone by using the Suzuki-Miyaura coupling reaction as the key step. The estrone-isoquinoline hybridized compound showed selective inhibitory activity against the proliferation and VEGF-induced migration of HUVEC.