Stimulation of glucose uptake in muscle cells by prolonged treatment with scriptide, a histone deacetylase inhibitor.

Glucose incorporation is regulated mainly by GLUT4 in skeletal muscles. Here we report that treatment of L6 myotubes with scriptide, a hydroxamic acid-based histone deacetylase (HDAC) inhibitor, stimulated 2-deoxyglucose uptake. The effect appeared only after 24 hr, resulting in 2.4-fold glucose uptake at treatment day 6. Scriptide acted synergistically with insulin, indicating it stimulated a distinct pathway from the insulin signaling pathway. It was not observed in undifferentiated myoblasts or 3T3-L1 adipocytes, suggesting a muscle-specific effect of scriptide. A five-carbon chain and hydroxamic acid, essential for histone deacetylase inhibition, were indispensable for this effect, and trichostatin A stimulated glucose uptake as well. Scriptide increased the cellular content of GLUT4, and induced GLUT4 translocation, but GLUT4 mRNA level did not change, indicating scriptide functions posttranslationally. Our results indicated a novel function for HDAC inhibitors of increasing GLUT4 content and its translocation in muscle cells, resulting in stimulation of glucose uptake.

Design and application of a new cryptic-plasmid-based shuttle vector for Magnetospirillum magneticum.

A 3.7-kb cryptic plasmid designated pMGT was found in Magnetospirillum magneticum MGT-1. It was characterized and used for the development of an improved expression system in strain AMB-1 through the construction of a shuttle vector, pUMG. An electroporation method for magnetic bacteria that uses the cryptic plasmid was also developed.

Effects of taurine on serum cholesterol levels and development of atherosclerosis in spontaneously hyperlipidaemic mice.

1. The effects of two naturally occurring substances, namely taurine and catechins, on serum cholesterol levels and on the progression of atherosclerotic lesions were evaluated using spontaneously hyperlipidaemic (SHL) mice as an animal model of atherogenesis. 2. Twelve weeks treatment of SHL mice with taurine (1% in drinking water) significantly elevated serum high-density lipoprotein-cholesterol (HDL-C) levels without affecting levels of low-density lipoprotein- and very low-density lipoprotein-cholesterol. In addition, taurine suppressed the development of atherosclerotic lesions by 29%, as determined by oil red O-stained areas in cross-sections of the aorta. 3. In contrast, 12 weeks treatment with a catechin mixture had no apparent effect on serum cholesterol levels and on the progression of atherosclerosis. 4. Serum levels of thiobarbituric acid-reactive substances, an index of oxidized substances, significantly decreased from 9.6 to 6.7 nmol/mL following taurine treatment. 5. We suggest that retardation of atherosclerosis by taurine in SHL mice may be related to decreases in oxidized substances and increases in serum HDL-C levels.

XIB4035, a novel nonpeptidyl small molecule agonist for GFRalpha-1.

We investigated the agonistic activities of N(4)-(7-chloro-2-[(E)-2-(2-chloro-phenyl)-vinyl]-quinolin-4-yl)-N(1),N(1)-diethyl-pentane-1,4-diamine (XIB4035), at the glial cell line-derived neurotrophic factor (GDNF) family receptoralpha-1(GFRalpha-1) in Neuro-2A cells, a mouse neuroblastoma cell line which is a suitable model for investigating functions mediated through GFRalpha-1. XIB4035 concentration-dependently inhibited [(125)I]GDNF binding in Neuro-2A cells with an IC(50) of 10.4 microM. GDNF induced autophosphorylation of Ret protein, and promoted neurite outgrowth in Neuro-2A cells. XIB4035, like GDNF, induced Ret autophosphorylation in the Neuro-2A cells. Moreover, XIB4035 promoted neurite outgrowth in a concentration-dependent manner. These results show that XIB4035 may act as an agonist at GFRalpha-1 receptor complex, and mimic neurotrophic effects of GDNF in Neuro-2A cells. This is an interesting finding showing that a nonpeptidyl small molecule is capable of inducing activation of a receptor that normally bind a relatively large protein ligand such as GDNF.