Migrastatin acts as a muscarinic acetylcholine receptor antagonist.

Migrastatin and its analogs have various biological activities such as inhibition of cell migration and anchorage-independent growth of cancer cells. Although its biosynthesis and chemical synthesis have been under investigation, little is known about the biological target of migrastatin. Here, we found that migrastatin inhibited intracellular calcium mobilization induced by carbachol in neuroblastoma SK-N-SH cells without affecting Ca2+ mobilization and cAMP accumulation induced by ligands of other receptors.

Our research on proton pumping ATPases over three decades: their biochemistry, molecular biology and cell biology.

ATP is synthesized by F-type proton-translocating ATPases (F-ATPases) coupled with an electrochemical proton gradient established by an electron transfer chain. This mechanism is ubiquitously found in mitochondria, chloroplasts and bacteria. Vacuolar-type ATPases (V-ATPases) are found in endomembrane organelles, including lysosomes, endosomes, synaptic vesicles, etc.

Augmentation of cellular immunity by kigamicin D.

Kigamicin D did not show any immunosuppressive activity in mixed lymphocyte culture reaction and mitogen induced lymphocyte blastogenesis in vitro and graft versus host reaction in vivo. Natural killer cell activity in spleen cells was not affected by oral administration of kigamicin D. Instead, delayed-type hypersensitivity response to sheep red blood cells was stimulated at a broad dosage level.

Antitumor effect of kigamicin D on mouse tumor models.

Kigamicin D is a novel anticancer agent that was identified using a new screening strategy that targets the tolerance of cancer cells to nutrient starvation [1, 2]. Oral administration of kigamicin D was previously described to show a strong antitumor effect in human tumor xenograft models of pancreatic tumors [2]. In this paper we describe that kigamicin D shows the same selective cytotoxicity against normal human cells such as lung fibroblast and prostate stromal cells under nutrient starved condition as against cancer cells.

Stochastic proton pumping ATPases: from single molecules to diverse physiological roles.

We discuss the most recent reports on two proton pumps, F-ATPase (ATP synthase) and V-ATPase (endomembrane proton pump). They are formed from similar extrinsic (F1 or V1) and intrinsic (Fo or Vo) membrane sectors, and couple chemistry and proton transport through subunit rotation for apparently different physiological roles. Emphasis is placed on the stochastic rotational catalysis of F-ATPase and isoforms of V-ATPase.

Synthesis and inhibitory activity of 8-substituted 2-deoxy-beta-KDO against CMP-KDO synthetase.

3-Deoxy-D-manno-octulosonate cytidyltransferase (CMP-KDO synthetase) is involved in the biosynthesis of lipopolysaccharide (LPS) which is an essential component of the outer membrane of gram-negative bacteria. New CMP-KDO synthetase inhibitors, 8-substituted derivatives of 2-deoxy-beta-KDO (2) have been prepared. Compounds 8, 11, 15 and 16 in which the 8-hydroxyl group of 2 is replaced by guanidine, di(carbamoylethyl)amino, p-methoxy- or p-nitro-benzyloxycarbonylamino, respectively affect moderately the CMP-KDO synthetase activity.

Insulin-like growth factor I secreted from prostate stromal cells mediates tumor-stromal cell interactions of prostate cancer.

Prostate cancer shows high expression of type I insulin-like growth factor (IGF-I) receptor (IGF-IR) and prostate stromal cells (PrSC) produce IGF-I. Although high plasma level of IGF-I is a risk factor of prostate cancer, the significance of the prostate stromal IGF-I in the regulation of prostate cancer remains elusive. Here we show that the stromal IGF-I certainly regulates the development of prostate cancer.

A new teleocidin analog from Streptomyces sp. MM216-87F4 induces substance P release from rat dorsal root ganglion neurons.

A new teleocidin analog was isolated from the fermentation medium of Streptomyces sp. MM216-87F4 and its structure was elucidated as 14-O-(N-acetylglucosaminyl) teleocidin A (GlcNAc-TA). GlcNAc-TA induces the translocation of protein kinases Calpha and theta fused with enhanced green fluorescent protein (PKCalpha-EGFP and PKCtheta-EGFP) to the plasma membrane in stable transfectants, and reduces intracellular calcium mobilization induced by agonists of G-protein coupled receptors in various cell lines without causing irritation of the mouse ear.

Establishment of a highly tumorigenic LNCaP cell line having inflammatory cytokine resistance.

Human androgen-dependent prostate cancer LNCaP cells are low tumorigenic even in immunodeficient mice and were killed by the synergistic effect of inflammatory cytokines, IL-beta and IL-6. To establish a highly tumorigenic LNCaP cell line, we isolated the cytokine-resistant LNCaP-CR cell line and examined the phenotypes. The parental LNCaP cells were induced to commit apoptosis by the addition of IL-1beta and IL-6, but LNCaP-CR cells showed strong resistance against the cytokine action.

Stochastic high-speed rotation of Escherichia coli ATP synthase F1 sector: the epsilon subunit-sensitive rotation.

The gamma subunit of the ATP synthase F(1) sector rotates at the center of the alpha(3)beta(3) hexamer during ATP hydrolysis. A gold bead (40-200 nm diameter) was attached to the gamma subunit of Escherichia coli F(1), and then its ATP hydrolysis-dependent rotation was studied. The rotation speeds were variable, showing stochastic fluctuation.

New naphthoquinones, f13102A and B, from a fungus strain F-13102.

Deficiency of Fas-mediated apoptosis is one of the mechanisms involved in the immune evasion by tumors. Thus, it might be a practical approach for cancer treatment that Fas-mediated apoptosis in tumor cells is modified by drugs. In the course of screening, we have isolated two new naphthoquinones, f13102A and B, from the culture broth of fungus strain F-13102.

Synthesis and activity of tyropeptin A derivatives as potent and selective inhibitors of mammalian 20S proteasome.

Tyropeptin A, a potent proteasome inhibitor, was isolated from the culture broth of Kitasatospora sp. MK993-dF2. We synthesized the derivatives of tyropeptin A to enhance its inhibitory potency.

CH/pi hydrogen bonds as evidenced in the substrate specificity of acetylcholine esterase.

The crystal structure of acetylcholine esterase (AchE) in complex with various inhibitors, investigated as drugs for improvement of the cognitive ability of early stage Alzheimer's disease, has been analyzed with the use of our program CHPI. A number of CH/pi hydrogen bonds have been disclosed in the binding of the inhibitors with Torpedo californica AchE. It has been demonstrated that, in order to be effective in the binding with AchE, C-H bonds in the inhibitor need not be polarized.

Prevention of neomycin-induced nephrotoxic event in pig proximal tubular epithelial cell line by apolipoprotein E3.

Nephrotoxicity is one of critical problems of aminoglycoside antibiotics. We examined the protective effect of apolipoprotein E3 (apoE3), one of ligands for megalin, on neomycin-induced extracellular release of lactate dehydrogenase, a marker of cell necrosis using pig proximal tubular LLC-PK1 cells. Neomycin significantly induced the extracellular release of lactate dehydrogenase, but apoE3 successfully suppressed it.

Caprazamycins, novel lipo-nucleoside antibiotics, from Streptomyces sp. II. Structure elucidation of caprazamycins.

Novel antibiotics, active against acid-fast bacteria, caprazamycins, were isolated from the culture broth of Streptomyces sp. MK730-62F2. The planar structures of the compounds were determined by 2D NMR spectroscopic study.

Absolute configuration of kigamicins A, C and D.

The stereochemistry of kigamicins A (1), C (2) and D (3) were elucidated by a combination of X-ray crystallographic analysis and degradation studies. The absolute structures of kigamicins thus determined were depicted as shown in Fig. 2.

A proof of the specificity of kanamycin-ribosomal RNA interaction with designed synthetic analogs and the antibacterial activity.

The binding specificity of designed synthetic kanamycins with model RNA sequences (wild-type and point-mutated type) derived from the 16S ribosomal A-site was evaluated using surface plasmon resonance imaging. It was observed that kanamycins have nonspecific and multiple interactions with RNA hairpins and that the binding potency is not always proportional to the antimicrobial activity.

Structure-based design of derivatives of tyropeptin A as the potent and selective inhibitors of mammalian 20S proteasome.

Tyropeptin A, a new potent proteasome inhibitor, was produced by Kitasatospora sp. MK993-dF2. To enhance the inhibitory potency of tyropeptin A, we constructed the structural model of tyropeptin A bound to the site responsible for the chymotrypsin-like activity of mammalian 20S proteasome.

Apolipoprotein E3 (apoE3) safeguards pig proximal tubular LLC-PK1 cells against reduction in SGLT1 activity induced by gentamicin C.

Megalin, a family of endocytic receptors related to the low-density lipoprotein (LDL) receptor, is a major pathway for proximal tubular aminoglycoside accumulation. We previously reported that aminoglycoside antibiotics reduce SGLT1-dependent glucose transport in pig proximal tubular epithelial LLC-PK1 cells in parallel with the order of their nephrotoxicity. In this study, using a model of gentamicin C (GMC)-induced reduction in SGLT1 activity, we examined whether ligands for megalin protect LLC-PK1 cells from the GMC-induced reduction in SGLT1 activity.

Synthesis and biological activity of sulphostin analogues, novel dipeptidyl peptidase IV inhibitors.

The structure of sulphostin (1), a novel dipeptidyl peptidase IV (DPP-IV) inhibitor, is consisted of three key functional groups, including a characteristic amino(sulfoamino)phosphinyl group, on a piperidine ring. To examine the relationship between its structure and the inhibitory activity against DPP-IV, various analogues were synthesized and their activities were investigated. These results indicated that all of the functional groups on the piperidine ring were crucial to the DPP-IV inhibitory activity of sulphostin, and that the sulfonic acid group, which constructed the amino(sulfoamino)phosphinyl group, contributed to the stability of the compound.

Involvement of doxorubicin-induced Fas expression in the antitumor effect of doxorubicin on Lewis lung carcinoma in vivo.

Deficiency of Fas expression is one of mechanisms involved in the immune evasion by tumors. Several antitumor drugs, such as doxorubicin (DOX) increase Fas expression in tumor cells and sensitize the cells to Fas-mediated apoptosis in vitro. However, the significance of the Fas expression in vivo is still unclear.

A microplate assay for selective measurement of growth of epithelial tumor cells in direct coculture with stromal cells.

Stromal cells play an important role in regulating epithelial malignancies through diffusible factors and adhesion. Modulation of the tumor-stromal cell interaction is an attractive target for new antitumor strategies. To screen for a modulator of the interaction, we have now developed a quantitative colorimetric assay for measurement of tumor cell growth in coculture with stromal cells using rhodanile blue dye.

First synthesis and determination of the absolute configuration of sulphostin, a novel inhibitor of dipeptidyl peptidase IV.

Sulphostin, a novel dipeptidyl peptidase IV (DPP-IV) inhibitor, was isolated from the culture broth of Streptomyces sp. MK251-43F3. Determination of the absolute configurations of two asymmetric atoms using the natural product was not achieved due to the small amount of the compound obtained.