New polyhydroxylated sterols stylisterols A-C and a novel 5,19-cyclosterol hatomasterol from the Okinawan marine sponge Stylissa sp

New polyhydroxylated sterols, stylisterol A-C (1-3), and a novel 5,19-cyclosterol, hatomasterol (4) were isolated from the Okinawan sponge Stylissa sp. Structural determinations of these compounds were made by spectroscopic analysis and chemical conversion. Assessment of cytotoxicity toward HeLa cells was also determined.     

TGF-beta receptor kinase inhibitor enhances growth and integrity of embryonic stem cell-derived endothelial cells

Recent findings have shown that embryonic vascular progenitor cells are capable of differentiating into mural and endothelial cells. However, the molecular mechanisms that regulate their differentiation, proliferation, and endothelial sheet formation remain to be elucidated. Here, we show that members of the transforming growth factor (TGF)-beta superfamily play important roles during differentiation of vascular progenitor cells derived from mouse embryonic stem cells (ESCs) and from 8.5-days postcoitum embryos. TGF-beta and activin inhibited proliferation and sheet formation of endothelial cells. Interestingly, SB-431542, a synthetic molecule that inhibits the kinases of receptors for TGF-beta and activin, facilitated proliferation and sheet formation of ESC-derived endothelial cells. Moreover, SB-431542 up-regulated the expression of claudin-5, an endothelial specific component of tight junctions. These results suggest that endogenous TGF-beta/activin signals play important roles in regulating vascular growth and permeability.     

Activation of the Sarcophaga lectin gene promoter in transgenic Drosophila

We established transgenic Drosophila strains in which the lacZ gene was expressed under the control of the 5'-upstream regulatory region of the Sarcophaga lectin gene promoter (3.1 kbp). The reporter gene was expressed in the fat bodies of the transgenic larvae when they were immunized by body pricking or treatment with Escherichia coli, which was the same as the Sarcophaga lectin gene expression in Sarcophaga larvae. However, the same reporter gene was found to be expressed constitutively in the digestive tracts of the transgenic larvae even without immunization.     

Syntheses of racemic and diastereomeric mixtures of 3,7,11,15-tetramethylhentriacontane and 4,8,12,16-tetramethyldotriacontane,the cuticular tetramethylalkanes of the tsetse fly,Glossina brevipalpis

Cuticular hydrocarbons of the tsetse fly, Glossina brevipalpis, contain 3,7,11,15-tetramethylhentriacontane and 4,8,12,16-tetramethyldotriacontane as possible candidates for its contact sex pheromone. These were synthesized as racemic and diastereomeric mixtures starting from racemic citronellol and employing phenyl-sulfone-mediated chain-elongation as the key reaction.     

Aromatization of 16alpha-hydroxyandrostenedione by human placental microsomes: effect of preincubation with suicide substrates of androstenedione aromatization

Estrogen synthase (aromatase) catalyzes the aromatization of androstenedione (AD) as well as 16alpha-hydroxyandrostenedione (16alpha-OHAD) leading to estrone and estriol, respectively. We found that several steroid analogs including 4-hydroxyandrostenedione (1), 6-oxoandrostenedione (6-oxoAD, 2) and its 19-hydroxy analog (3), 10beta-acetoxyestr-5-ene-7,17-dione (4), androst-5-ene-4,7,17-trione (5), and 17alpha-ethynyl-19-norteststerone (6), which are known suicide inactivators of AD aromatization, are not effective in inactivating 16alpha-OHAD aromatization in a time-dependent manner. The compounds were tested with the use of human placental microsomes and 1beta-tritiated-16alpha-OHAD as the substrate. The results of the tritium water method of 16alpha-OHAD aromatization was confirmed by the gas chromatography-mass spectrometry (GC-MS) method of estriol formation. The 1beta-tritiated-AD was used to measure AD aromatization as a positive control for these experiments. The compounds were tested at concentrations up to 40-fold higher than the K(i)'s determined for inhibition of AD aromatization. These studies suggest that differences exist in the binding site structures responsible for aromatization of 16alpha-OHAD and AD.     

Regulation of the expression of two female-predominant CYP3A mRNAs (CYP3A41 and CYP3A44) in mouse liver by sex and growth hormones

A second female-predominant murine CYP3A, CYP3A44, was isolated from liver and its mRNA expression was compared with that of the previously described CYP3A41. The expression of CYP3A44 was relatively constant after birth in females, whereas it gradually declined in males after 5 weeks of age. The expression of CYP3A41 increased with age in females after 3 weeks of age, whereas it gradually declined in males after 5 weeks of age. Hypophysectomy and growth hormone replacement indicated that expression of both CYP3A mRNAs in females was dependent on the feminine plasma growth hormone profile. Estradiol induced the expression of both mRNAs and the effect was dependent on the presence of the pituitary gland. These observations suggest that endocrine control of expression might be similar, but not identical, for two female-predominant CYP3A mRNAs.     

Functional and physical interaction between Sgs1 and Top3 and Sgs1-independent function of Top3 in DNA recombination repair

A mutant allele of SGS1 of Saccharomyces cerevisiae was identified as a suppressor of the slow-growth phenotype of top3 mutants. We previously reported the involvement of Top3 via the interaction with the N-terminal region of Sgs1 in the complementation of methylmethanesulfonate (MMS) sensitivity and the suppression of hyper recombination of a sgs1 mutant. In this study, we found that several amino acids residues in the N-terminal region of Sgs1 between residues 4 and 33 were responsible for binding to Top3 and essential for complementing the sensitivity to MMS of sgsl cells. Two-hybrid assays suggested that the region of Top3 responsible for the binding to Sgs1 was bipartite, with portion in the N- and C-terminal domains. Although disruption of the SGS1 gene suppressed the semi-lethality of the top3 mutant of strain MR, the sgsl-top3 double mutant grew more slowly and was more sensitive to MMS than the sgsl single mutant, indicating that Top3 plays some role independently of Sgs1. The DNA topoisomerase activity of Top3 was required for the Top3 function to repair DNA damages induced by MMS, as shown by the fact that the TOP3 gene carrying a mutation (Phe for Tyr) at the amino acid residue essential for its activity (residue 356) failed to restore the MMS sensitivity of sgs1-top3 to the level of that of the sgs1 single mutant. Epistatic analysis using the sgs1-top3 double mutant, rad52 mutant and sgs1-top3-rad52 triple mutant indicated that TOP3 belongs to the RAD52 recombinational repair pathway.