GABA receptors ameliorate Hcy-mediated integrin shedding and constrictive collagen remodeling in microvascular endothelial cells

Mammalian endothelial cells are deficient in cystathionine β synthetase (CBS) activity, which is responsible for homocysteine (Hcy) clearance. This deficiency makes the endothelium theprime target for Hcy toxicity. Hcy induces integrin shedding in microvascular endothelial cells (MVEC) by increasing matrix metalloproteinase (MMP). Hcy competes with inhibitory neurotransmitter γ aminobutyric acid (GABA)-A receptor. We hypothesized that Hcy transduces MVEC remodeling by increasing metalloproteinase activity and shedding β-1 integrin by inactivating the GABA-A/B receptors, thus behaving as an excitatory neurotransmitter. MVEC were isolated from mouse brain. The presence of GABA-A receptor was determined by immunolabeling. It was induced by muscimol, an agonist of GABA-A receptors as measured by Western blot analysis. Hcy induced MMP-2 activity in a dose- and time-dependent maner, measured by zymography. GABA-A/B receptors ameliorated the Hcy-mediated MMP-2 activation. Hcy selectively increased the levels of tissue inhibitor of metalloproteinase (TIMP)-1 and TIMP-3 but decreased the levels of TIMP-4. Treatment with muscimol decreased the levels of TIMP-1 and TIMP-3 and increased the levels of TIMP-4 to control. Hcy caused a robust increae in the levels of a disintegrin and metalloproteinase (ADAM)-12. In the medium of MVEC reated with Hcy, the levels of β-1 integrin were significantly increased. Treatment with muscimol or baclofen (GABA-B receptor agonist) ameliorated the levels significantly increased. Treatment with muscimol or baclofen (GABA-B receptor agonist) ameliorated the levels of β-1 integrin in the medium. These results suggested that Hcy induced DAM-12. Significantly, Hcy facilitated the β-1 integrin shedding. Treatment of MVEC with muscimole or baclofen during Hcy administration ameliorated the expression of metalloproteinase, integrin-shedding, and constrictive collagen remodeling, suggesting a role of Hcy in GABA receptor-mediated cerebrovascular remodeling.     

Solution NMR structure of the ribosomal protein RP-L35Ae from Pyrococcus furiosus

The ribosome consists of small and large subunits each composed of dozens of proteins and RNA molecules. However, the functions of many of the individual protomers within the ribosome are still unknown. In this article, we describe the solution NMR structure of the ribosomal protein RP-L35Ae from the archaeon Pyrococcus furiosus. RP-L35Ae is buried within the large subunit of the ribosome and belongs to Pfam protein domain family PF01247, which is highly conserved in eukaryotes, present in a few archaeal genomes, but absent in bacteria. The protein adopts a six-stranded anti-parallel β-barrel analogous to the "tRNA binding motif" fold. The structure of the P. furiosus RP-L35Ae presented in this article constitutes the first structural representative from this protein domain family.     

The discovery of moriniafungin, a novel sordarin derivative produced by Morinia pestalozzioides

A novel sordarin derivative, moriniafungin (1), containing a 2-hydroxysebacic acid residue linked to C-3' of the sordarose residue of sordarin through a 1,3-dioxolan-4-one ring was isolated from the fungus Morinia pestalozzioides. Isolation of moriniafungin employed a highly specific bioassay consisting of a panel of Saccharomyces cerevisiae strains containing chimeric eEF2 for Candida glabrata, Candida krusei, Candida lusitaniae, Crytpococcus neoformans, and Aspergillus fumigatus as well as wild type and human eEF2. Moriniafungin exhibited an MIC of 6 microg/mL versus Candida albicans and IC(50)'s ranging from 0.9 to 70 microg/mL against a panel of clinically relevant Candida strains. Moriniafungin was shown to inhibit in vitro translation in the chimeric S. cerevisae strains at levels consistent with the observed IC(50). Moriniafungin has the broadest antifungal spectrum and most potent activity of any natural sordarin analog identified to date.     

Effects of atropine and L-NAME on cutaneous blood flow during body heating in humans.

We sought to investigate further the roles of sweating, ACh spillover, and nitric oxide (NO) in the neurally mediated cutaneous vasodilation during body heating in humans. Six subjects were heated with a water-perfused suit while cutaneous blood flow was measured with a laser-Doppler flowmeter. After a rise in core temperature (1. 0 +/- 0.1 degrees C) and the establishment of cutaneous vasodilation, atropine and subsequently the NO synthase inhibitor N(G)-nitro-L-arginine methyl ester (L-NAME) were given to the forearm via a brachial artery catheter. After atropine infusion, cutaneous vascular conductance (CVC) remained constant in five of six subjects, whereas L-NAME administration blunted the rise in CVC in three of six subjects. A subsequent set of studies using intradermal microdialysis probes to selectively deliver drugs into forearm skin confirmed that atropine did not affect CVC. However, perfusion of L-NAME resulted in a significant decrease in CVC (37 +/- 4%, P < 0.05). The results indicate that neither sweating nor NO release via muscarinic receptor activation is essential to sustain cutaneous dilation during heating in humans.     

Gene disruption in mice: Models of development and disease

Gene targeting technology in mice by homologous recombination has become an important method to generate loss-of-function of genes in a predetermined locus. Although the inactivation is limited to irreversible alteration of chromosomal DNA and a surprising variety of genes have given unexpected and disappointing results, modification of the basic technology now provides additional choices for a more specific and variety of manipulations of the mouse genome. This includes conditional cell-type specific gene targeting, knockin technique and the induction of the specific balanced chromosomal translocations. In the past decade this technique not only generated a wealth of knowledge concerning the roles of growth factors, oncogenes, hormone receptors and Hox genes but also helped to produce animal models for several human genetic disorders. In the future it may provide more powerful and necessary tools to dissect the psychiatric disorders, understanding the complex central nervous system and to correct the inherited disorders.     

Multiple forms of DNA-dependent RNA polymerases in Xenopus laevis. Rapid purification and structural and immunological properties

DNA-dependent RNA polymerases I, II, and III (EC 2.7.7.6) were isolated from Xenopus laevis ovaries. The soluble enzymes were precipitated with polyethyleneimine and subjected to chromatography on heparin-Sepharose, DEAE-Sephadex, and phosphocellulose. RNA polymerase I was subjected to an additional chromatographic step on CM-Sephadex. The procedure required 40 h and produced purified RNA polymerase forms IA, IIA, and III in yields of 5 to 40%. The specific activities of RNA polymerases IIA and III (on native DNA) were comparable to those reported from other eukaryotic sources, whereas that of form IA was severalfold greater than the specific activities reported for other purified class I RNA polymerases. The complex subunit compositions of chromatographically purified RNA polymerases IA, IIA, and III were distinct when analyzed by polyacrylamide gradient gel electrophoresis under denaturing conditions, although all three classes contained polypeptides with Mr = 29,000, 23,000, and 19,000. Antibodies prepared against RNA polymerase III showed common antigenic determinants within the class I, II, and III enzymes. The sites responsible for the cross-reaction are located, at least in part, on the common 29,000-dalton polypeptide.     

On the functions of lithium: The mood stabilizer

Lithium, despite its simple structure, has numerous biological effects. It also has a remarkable therapeutic effect in the prophylactic treatment of manic depression, and is finding a role in controlling aggressive and self-mutilating behavior. The special feature of lithium is that it only acts on overactive systems to bring them back to normal, without affecting the stable system. The mechanisms of action of this simple cation are still largely unknown although the inositol depletion theory is the most widely accepted model. A recent paper⁽¹⁾ described a different molecular mechanism for its effect on development, which may also explain its action in manic depression.     

The structure and expression of a distantly related member of the beta-gamma crystallin super gene family from Xenopus.

In an attempt to understand amphibian crystallin gene regulation, we have isolated and partially characterized several genomic clones which hybridized to the gamma 1 cDNA probe from Rana temporaria. A complete sequence of one of these clones showed slight homology to the mammalian beta and gamma crystallins. The deduced amino acid sequence of the coding region and its alignment as a folding unit indicated that all the topologically equivalent residues involved in maintaining the protein folding pattern are highly conserved. Northern blot analysis of total RNAs derived from several adult tissues, including eye lens, suggested that an RNA of approximately 700 nucleotides long is present in lens, heart, spleen and embryos of later stages of development but not in retina, oocytes and embryos of early developmental stages.