Ascochlorin derivatives as ligands for nuclear hormone receptors.

Nuclear receptor family proteins are structurally related transcription factors activated by specific lipophilic compounds. Because they are activated by a variety of hormonal molecules, including retinoic acid, vitamin D, and steroid hormones, they are assumed to be promising targets for clinical drugs. We previously found that one ascochlorin (1) derivative, 4-O-carboxymethyl-ascochlorin (2), is a potent agonist of peroxisome proliferator activated receptor gamma (PPARgamma). Here, we synthesized derivatives of 1, designated as a lead compound, to create new modulators of nuclear hormone receptors. Two derivatives, 4-O-carboxymethyl-2-O-methylascochlorin (9) and 4-O-isonicotinoyl-2-O-methylascochlorin (10), showed improved agonistic activity for PPARgamma and induced differentiation of a progenitor cell line, C3H10T1/2. We also found that 1, dehydroascofuranon (29), and a 2,4-O-diacetyl-1-carboxylic acid derivative of 1 (5) specifically activated estrogen receptors, PPARalpha, and an androgen receptor. All of the derivatives (1-29) activated the pregnane X receptor. These results suggest that the chemical structure of 1 is useful in designing novel modulators of nuclear receptors.

MESENCHYME CELLS IN STARFISH DEVELOPMENT: EFFECT OF TUNICAMYCIN ON THEIR DIFFERENTIATION, MIGRATION AND FUNCTION.

The effect of tunicamycin, an inhibitor of protein glycosylation, on starfish development was investigated. Specific developmental events such as 1) bulging of the archenteron tip, 2) migration of mesenchyme cells, 3) formation of coelomic pouches and 4) mouth formation, are inhibited in the presence of this drug. These events are discussed in connection with differentiation, migration and function of mesenchyme cells. The possibility is discussed that tunicamycin exerts its effect by interfering with de novo synthesis of a cell surface factor(s) supporting dynamic cell surface activities.

PPARgamma activation and adipocyte differentiation induced by AS-6, a prenyl-phenol antidiabetic antibiotic.

The prenyl-phenol antibiotics ascochlorin-related compounds, are known to reduce serum cholesterol and triglyceride, suppress hypertension, and ameliorate types-I and II diabetes. However, little is known about the molecular mechanism for these physiological effects. Here we report that the ascochlorin derivative, 4-O-carboxymethyl ascochlorin (AS-6) acts as a potent activator of the nuclear hormone receptor, PPARgamma, although it does not activate the related receptors, PPARalpha, PPARdelta or RARalpha. AS-6 interacts directly with the PPARgamma molecule in vitro, and induces differentiation of the mouse preadipocyte cell line 3T3-L1. Our results suggest that AS-6 is a partial agonist for PPARgamma with a novel chemical structure.

Cloning, nucleotide sequencing, and expression of the beta-galactosidase-encoding gene (lacA) from Aspergillus oryzae.

lacA coding for beta-galactosidase (beta-gal) was cloned from the genomic DNA of Aspergillus oryzae RIB40. There were 9 exons in lacA and the coding region of 3,015 bp encoded a protein of 1,005 aa with a deduced molecular mass of 109,898. A. oryzae lacA was highly homologous to fungal beta-gals, with the highest aa identity of 70.7% to A. niger lacA, and also showed significant identity to acid beta-gals belonging to family 35 glycosyl hydrolases. Approximately 10 copies of lacA under control of A. oryzae glaA promoter were integrated into the chromosome of A. oryzae M-2-3. The recombinant strain expressed more than 700-fold of the beta-gal activity as compared to the wild type strain under induction by maltose.