Toshiyuki Mori

Role of STAT-3 in regulation of hepatic gluconeogenic genes and carbohydrate metabolism in vivo.

The transcription factor, signal transducer and activator of transcription-3 (STAT-3) contributes to various physiological processes. Here we show that mice with liver-specific deficiency in STAT-3, achieved using the Cre-loxP system, show insulin resistance associated with increased hepatic expression of gluconeogenic genes. Restoration of hepatic STAT-3 expression in these mice, using adenovirus-mediated gene transfer, corrected the metabolic abnormalities and the alterations in hepatic expression of gluconeogenic genes. Overexpression of STAT-3 in cultured hepatocytes inhibited gluconeogenic gene expression independently of peroxisome proliferator-activated receptor-γ coactivator-1α (PGC-1α), an upstream regulator of gluconeogenic genes. Liver-specific expression of a constitutively active form of STAT-3, achieved by infection with an adenovirus vector, markedly reduced blood glucose, plasma insulin concentrations and hepatic gluconeogenic gene expression in diabetic mice. Hepatic STAT-3 signaling is thus essential for normal glucose homeostasis and may provide new therapeutic targets for diabetes mellitus.

The Molecular Scaffold Kinase Suppressor of Ras 1 (KSR1) Regulates Adipogenesis

ABSTRACT Mitogen-activated protein kinase pathways are implicated in the regulation of cell differentiation, although their precise roles in many differentiation programs remain elusive. The Raf/MEK/extracellular signal-regulated kinase (ERK) kinase cascade has been proposed to both promote and inhibit adipogenesis. Here, we titrate expression of the molecular scaffold kinase suppressor of Ras 1 (KSR1) to regulate signaling through the Raf/MEK/ERK/p90 ribosomal S6 kinase (RSK) kinase cascade and show how it determines adipogenic potential. Deletion of KSR1 prevents adipogenesis in vitro, which can be rescued by introduction of low levels of KSR1. Appropriate levels of KSR1 coordinate ERK and RSK activation with C/EBPβ synthesis leading to the phosphorylation and stabilization of C/EBPβ at the precise moment it is required within the adipogenic program. Elevated levels of KSR1 expression, previously shown to enhance cell proliferation, promote high, sustained ERK activation that phosphorylates and inhibits peroxisome proliferator-activated receptor gamma, inhibiting adipogenesis. Titration of KSR1 expression reveals how a molecular scaffold can modulate the intensity and duration of signaling emanating from a single pathway to dictate cell fate.

Requirement for 3-phosphoinositide-dependent kinase-1 (PDK-1) in insulin-induced glucose uptake in immortalized brown adipocytes

To provide insight into the physiological importance of 3-phosphoinositide-dependent kinase-1 (PDK-1) in the metabolic actions of insulin, we have generated mice that harbor a PDK-1 gene containing LoxP sites (PDK-1lox/lox mice) and established immortalized brown preadipocyte cell lines both from these animals and from wild-type mice. Exposure to appropriate hormonal inducers resulted in the differentiation of >80% of the immortalized brown preadipocytes derived from both types of mice into mature adipocytes. Introduction of the Cre recombinase with the use of adenovirus-mediated gene transfer induced a dose-dependent decrease in the abundance of PDK-1 in PDK-1lox/lox adipocytes but not in the wild-type cells. In Cre-expressing PDK-1lox/lox adipocytes in which the abundance of PDK-1 was reduced by ∼85%, the insulin-induced phosphorylation both of Akt on threonine 308 and of p70 S6 kinase on threonine-389 was markedly inhibited. The phosphorylation both of Akt on serine 473 and of p42 and p44 isoforms of mitogen-activated protein kinase induced by insulin was not affected by Cre expression, indicating that the latter specifically inhibits PDK-1-dependent signaling. Both glucose uptake and the translocation of glucose transporter 4 to the plasma membrane induced by insulin as well as glucose uptake induced by a constitutively active form of phosphoinositide 3-kinase were also greatly inhibited by Cre expression in PDK-1lox/lox adipocytes. Phosphorylation of AMP-activated protein kinase and glucose uptake induced by 5-aminoimidazole-4-carboxamide ribonucleoside (AICAR) were not affected by Cre expression in PDK-1lox/lox adipocytes. These results indicate that PDK-1 is essential for insulin-induced glucose uptake in adipocytes.

The acceleration of decomposition of potassium persulfate in the presence of sodium dodecyl sulfate and polymer particles as a model of emulsion polymerization system)

The decomposition rates of potassium persulfate (KPS) in aqueous solutions containing sodium dodecyl sulfate (SDS) in the presence of polystyrene or poly(methyl methacrylate) particles as models of emulsion polymerization systems were measured by isotachophoresis. “Free” SDS molecules dispersed in the monomolecular state had an ability to accelerate the KPS decomposition, but SDS molecules adsorbed onto the polymer particles did not accelerate it.

An isotachophoresis for the microdetermination of potassium persulphate as initiator in emulsion polymerization

An isotachophoresis (IP) was applied to determine the decomposition rate of potassium persulphate (KPS) as initiator in emulsion polymerization, in comparison with conventional iodometry and ferrometry. For the exact determination, the latter methods needed several milliliters of the emulsion pipetted from the polymerization system, whereas IP did only a few microliters. Moreover, the amount of sulphuric acid produced as the decomposition by-product was simultaneously determined by IP, which is impossible for iodometry and ferrometry.

Chemical deposition coatings from emulsifier-free anionic polymer emulsion onto anodized aluminum plate under stirring conditions

The chemical deposition from an anionic acrylic copolymer emulsion onto an anodized aluminum plate was carried out under various stirring conditions. The amount of polymer deposited was affected by the stirring rate. At higher stirring rates, the surface flatness of the obtained coating decreased, but the transparency (which was affected by the traces of bubbles, due to evolution of hydrogen gas from the surface of the plate in the deposition process) was improved. Under optimum stirring conditions an excellent coating having a flat surface and good transparency was obtained.

Polymer coating onto anodized aluminiun plate by anodic electrode position from alkali-swollen carboxylated acrylic emulsion

Polymer coating of an anodized aluminum plate was carried out by anodic electrodeposition from alkali-swollen ethyl acrylate-methyl methacrylate-methacrylic acid (45/45/10, mole ratio) terpolymer emulsion with dimethyl aminoethanol. The alkali-swollen state was controlled by heating time at 60°C prior to the elctrodeposition. The similar complicated behaviors were observed in the relationships between the alkali-swollen state and the primary current density, the current density after 2 min, the quantity of electricity, and the amount of polymer deposited. The appearance of coatings changed correspondingly with such behaviors. These results indicate that the properties of the coatings are complicatedly affected by the degree of alkali-swollen state.