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E Sugimoto

Publications and source records attributed to E Sugimoto.

At least 55 records · Page 3Linked to original sources
PubMed1994

The prevention of adipose differentiation of 3T3-L1 cells caused by retinoic acid is elicited through retinoic acid receptor alpha.

Retinoids, especially all-trans retinoic acid (RA), have been shown to inhibit the differentiation of preadipose cells. It is important to human health, especially to obesity, that the regulatory system for the differentiation of adipocytes is well defined. Previously, we have shown that retinoic acid receptor (RAR) gamma 2 gene expression is up-regulated by RA in 3T3-L1 preadipose cells. In this study, the RAR system was dissected and the RA-regulated function in 3T3-L1 cells was assigned to one given receptor. We used three synthetic retinoids; (1) Ro 41-5253, a selective RAR alpha antagonist, (2) Ch 55, an RAR alpha, beta and gamma agonist, and (3) Am 80, an RAR alpha and beta agonist, which has less affinity to RAR gamma. Ro 41-5253 reverted RA-induced inhibition of the differentiation of 3T3-L1 cells. However, there was no significant reversion in RA-induced RAR gamma mRNA level by treatment with Ro 41-5253. In the case of RAR agonists, both Am 80 and Ch 55 strongly inhibited the differentiation of 3T3-L1 cells. However, Am 80 weakly increased RAR gamma mRNA content less than did Ch 55. These findings suggest, that RAR alpha is involved in the prevention of adipose differentiation by RA in 3T3-L1 cells. Moreover, there seems no causal relationship between the prevention of adipose differentiation by RA and the up-regulation of RAR gamma 2 gene expression by RA in 3T3-L1 cells. We have shown the functional heterogeneity of RA action through different RARs in 3T3-L1 cells.

3T3 Cells↗
PubMed1993

Retinoic acid receptor gamma 2 gene expression is up-regulated by retinoic acid in 3T3-L1 preadipocytes.

Retinoids, especially all-trans retinoic acid (RA), have been shown to inhibit the differentiation of preadipose cells. In the present study, the expression of retinoic acid receptors (RAR alpha, beta and gamma) and retinoid X receptors (RXR alpha, beta and gamma) was examined by Northern blot analysis in rat adipose tissue and mouse 3T3-L1 adipose cells. The adipose tissue and/or 3T3-L1 cells expressed mRNAs for a number of nuclear retinoid receptors, including RAR alpha, beta and gamma, and RXR alpha, beta and gamma. RAR alpha, RAR gamma, RXR alpha and RXR beta mRNAs were abundant in adipose tissue and 3T3-L1 cells. RXR gamma mRNA was detected in adipose tissue but not in 3T3-L1 cells. Treatment of 3T3-L1 cells with 1 microM RA led to a 4-5-fold increase in the RAR gamma mRNA level, but only a trace amount of RAR beta mRNA was detected. RAR gamma mRNA expression was rapidly (within 2 h) induced by physiological concentrations of RA in a dose-dependent manner. The response of RAR gamma mRNA expression to RA was reversible; rapid disappearance of RAR gamma mRNA occurred on RA removal. In addition, the induction of RAR gamma expression did not require de novo protein synthesis, but was completely abolished by an inhibitor of RNA synthesis. Using RAR gamma 1 and gamma 2 isoform-specific probes, the patterns of RAR gamma 1 and gamma 2 mRNA expression in 3T3-L1 cells in the presence and absence of RA were examined. RAR gamma 1 mRNA was detected in 3T3-L1 cells but was not affected by RA treatment; however, RAR gamma 2 mRNA was strongly induced by RA.

3T3 Cells↗
PubMed1993

Vitamin D receptor gene expression is up-regulated by 1, 25-dihydroxyvitamin D3 in 3T3-L1 preadipocytes.

Vitamin D3, especially 1, 25-dihydroxyvitamin D3 (1, 25 (OH)2 D3), has been shown to inhibit the differentiation of preadipose cells. In the present study, the expression of vitamin D receptor (VDR) was examined by Northern blot analysis in rat adipose tissue and mouse 3T3-L1 adipose cells. The adipose tissue and 3T3-L1 cells expressed mRNA for VDR. Treatment of 3T3-L1 cells with 1 microM 1, 25 (OH)2 D3 led to a 4-5 fold increase in the VDR mRNA level. VDR mRNA expression was rapidly (within 4 hr) induced by physiological concentrations of 1,25 (OH)2 D3 in a dose-dependent manner. The induction of VDR expression did not require de novo protein synthesis but was completely abolished by an inhibitor of RNA synthesis.

3T3 Cells↗
PubMed1993

A specific binding of the cholecystokinin-releasing peptide (monitor peptide) to isolated rat small-intestinal cells.

A specific binding of the cholecystokinin (CCK)-releasing peptide (monitor peptide) to isolated rat jejunal mucosal cells was investigated. The 125I-labelled purified monitor peptide bound to the rat jejunal cells, and a large excess amount of the non-labelled monitor peptide inhibited the binding. The binding was completed within 60 min at 37 degrees C. The optimum pH for the binding was 8-9. A Scatchard plot of the specific binding was linear, and the dissociation constant was 50 nM. The density of the monitor-peptide-binding sites was high in duodenum but low in ileal and absent in colonic mucosa. A recombinant monitor peptide and four kinds of point mutants of it were prepared. The binding of the mutant monitor peptides to the cells indicated that only a trypsin inhibitor of the mutants could bind to the mucosal cells. Human pancreatic secretory trypsin inhibitor inhibited the specific binding, but other trypsin inhibitors, i.e. bovine basic pancreatic trypsin inhibitor, soybean trypsin inhibitor, egg-white trypsin inhibitor, leupeptin, antipain and FOY-305, did not affect the specific binding at all. These findings suggested that the specific binding site for the monitor peptide on the jejunal mucosal cells has a trypsin-like specificity, exhibiting a special specificity for the pancreatic-secretory-trypsin-inhibitor family. Autoradiography of an affinity-cross-linked complex of the 125I-labelled intact monitor peptide and the binding site suggested that its molecular mass was 33 kDa or 53 kDa in the presence or absence of 2-mercaptoethanol respectively.

Amino Acid Sequence↗
PubMed1993

Level of preadipocyte growth factor in rat adipose tissue which specifically permits the proliferation of preadipocytes is affected by restricted energy intake.

We previously reported the presence of a protein growth factor in rat adipose tissue which specifically permits the proliferation of 3T3-L1 and Ob1771 preadipocytes [Biochem. Biophys. Res. Commun. 1990;171:905-912, ref. 1] and which is hereinafter referred to as PAGF (preadipocyte growth factor). In this study, the effects of long-term restricted energy intake on the PAGF activity in rat epididymal and perirenal adipose tissue toward 3T3-L1 preadipocytes were investigated. When rats were subjected to restricted energy intake for three weeks, PAGF activity increased with energy intake. The body weight, epididymal and perirenal fat depot weights and glycerol 3-phosphate dehydrogenase activity also increased with the energy intake, whereas the lactate dehydrogenase activity remained almost constant in all energy intake groups. These results suggest that the PAGF in fat depots functions in response to energy intake and contributes to the de novo formation of adipocytes and the growth of adipose tissue. This factor may provide a useful tool for further elucidation of the relationship between energy storage in adipose tissue and adipose tissue development.

3T3-L1 Cells↗
PubMed1993

Rapid increase in the number of androgen receptors following electrical stimulation of the rat muscle.

The changes in the number of androgen receptors in rat gastrocnemius muscle following muscle contraction caused by electrical stimulation were investigated. The gastrocnemius muscle of one leg, which was selected at random for each rat, was stimulated with needle type electrodes, e.g. for 2 s at 10 V and 100 Hz, with 5-s intervals. The contralateral leg was left unstimulated as a control. One set consisted of ten such stimuli, followed by 5-min rest. Three sets every 2 days caused a statistically significant increase in muscle mass, the increase being about 2.5% after the 3rd day of stimulation, 4.4% after the 5th day, 5.9% after the 13th day and 8.3% after the 27th day compared with each control muscle (P < 0.001 in each case). The protein content also increased but the water content did not change. Stimulation over 4 weeks induced an increase in the area of the cross-section of the muscle fibres to about 30% more than that of the control muscles, though the total muscle fibre numbers were slightly, but significantly, reduced. Electromechanical properties supported the development of the muscle by stimulation, because the maximal isometric tetanic force and peak twitch force markedly increased in the stimulated muscle. The androgen receptors in the muscle cytosol fraction were determined by means of a binding assay involving [3H]methyltrienolone, which is an analogue of testosterone, the number having rapidly increased in the stimulated leg, when compared with that in the control leg, by about 25% after the 3rd day. The increase then slowed down, reaching a plateau after the 5th-day of stimulation.(ABSTRACT TRUNCATED AT 250 WORDS)

Analysis of Variance↗
PubMed1993

Differentiation of brown adipose cells in three-dimensional collagen gel culture.

Brown adipose cells are heat-producing cells through non-shivering thermogenesis by intramitochondrial "thermogenin". This specific protein is a marker for their cellular differentiation. It has long been known that cultured brown adipose cells in monolayer rapidly lose the thermogenin bioactivity. In this study, we cultured brown adipose cells in three-dimensional type I collagen gel matrix. Under this culture condition, they were able to survive, and differentiated morphologically and functionally for a long period of time, especially exhibited the characteristic immunohistochemical activity of thermogenin. These findings suggest that brown adipose cells differentiate in type I collagen gel. In this condition, cholera toxin or BRL 37344, one of beta 3-adrenoceptor agonists, specifically stimulated the brown adipose cells.

Adipose Tissue, Brown↗
PubMed1992

Molecular cloning and characterization of genes encoding rat pancreatic cholecystokinin (CCK)-releasing peptide (monitor peptide) and pancreatic secretory trypsin inhibitor (PSTI).

The genes encoding a rat pancreatic cholecystokinin (CCK)-releasing peptide (monitor peptide) and its structurally related peptide, rat pancreatic secretory trypsin inhibitor (PSTI), have been isolated and sequenced. The two genes share extremely high sequence similarity in the 5' flanking regions, suggesting that these regions may be responsible for the characteristic coordinate expression of the two peptides.

Amino Acid Sequence↗
PubMed1992

Monitor peptide gene expression is increased by exogenous CCK in the rat pancreas and in a rat pancreatic acinar cell line (AR4-2J).

Monitor peptide (CCK-releasing peptide) mRNA increased on the administration of CCK in rat pancreas and the AR4-2J pancreatic cell line. Subcutaneous injection of CCK into rats at 8 h intervals increased the level of monitor peptide mRNA in the pancreas. Concomitant injection of CCK antagonist CR-1409 strongly decreased it. The monitor peptide mRNA was also increased by CCK in AR4-2J cells and was decreased by the antagonist. These findings suggest that the plasma CCK induced by prolonged intake of a high protein diet may be responsible for the adaptative increase in the monitor peptide as well as exocrine proteases in the pancreas.

Amylases↗
PubMed1992

An extract of Gymnema sylvestre leaves and purified gymnemic acid inhibits glucose-stimulated gastric inhibitory peptide secretion in rats.

Gastric inhibitory peptide release into the portal vein in response to duodenal infusion of D-glucose was studied in the presence of a leaf extract of Gymnema sylvestre, purified gymnemic acid and inhibitors of some putative glucose sensors and carriers in the intestinal lumen. Intraduodenal infusion of D-glucose significantly increased the portal immunoreactive gastric inhibitory peptide concentration in a dose-dependent manner. The increase in the portal immunoreactive gastric inhibitory peptide induced by glucose was significantly depressed by concomitantly infused leaf extract of Gymnema sylvestre, purified gymnemic acid and phlorizin but not by cytochalasin B. Mannoheptulose, which inhibits glycolysis, and procaine and lidocaine, which inhibit the vagal glucoreceptor in the lumen, did not affect portal immunoreactive gastric inhibitory peptide concentrations. These results suggest that a glucose receptor, which interacts with the leaf extract of Gymnema sylvestre, purified gymnemic acid and phlorizin, exists for the release of immunoreactive gastric inhibitory peptide and that the glucose receptor for gastric inhibitory peptide release is not likely to be identical with a glucose transporter or a vagal glucoreceptor in the lumen.

3-O-Methylglucose↗
PubMed1992

Effects of chronic hypoxia on the whole-body insulin action in rats.

The effect of chronic hypoxia on the whole-body insulin action in rats was investigated. Rats were kept in a hypobaric hypoxia chamber maintained at a simulated altitude of 4000 m for 10 weeks. At the end of the experimental period, the mean body weight of the hypoxic rats was significantly lower than that of the control rats. The muscle weight to body ratio of the quadriceps muscle in hypoxic rats was larger than that in control rats, but those of the gastrocnemius, soleus, and extensor digitorum longus muscles did not differ between the control and hypoxic rats. On the other hand, the epididymal fat pads of hypoxic rats were markedly smaller than those of the control rats. The results of a euglycemic clamp experiment with infusions of 14 and 3.6 mU insulin.kg-1.min-1 indicated that the steady-state glucose infusion rate was not statistically different between hypoxic and control rats. It is suggested that chronic hypoxia did not influence the whole-body insulin action on glucose transport activity.

Adipose Tissue↗
PubMed1992

Lipoprotein lipase enzyme expression in 3T3-L1 adipocytes is posttranscriptionally down-regulated by retinoic acid.

The effects of all-trans retinoic acid (RA) on the lipoprotein lipase (LPL) activity, synthesis and mRNA content in 3T3-L1 adipocytes were studied. When fully differentiated 3T3-L1 adipocytes were exposed to RA, dose-dependent suppression of LPL activity was observed. The loss of activity reached a maximum of 60% of the control level and appeared to be due to an effect on synthesis of the enzyme, as judged from the decreased incorporation of [35S] methionine and [35S] cysteine into immunoprecipitable LPL. The LPL mRNA level remained unchanged under the same conditions. In contrast, no significant reduction in glycerol-3-phosphate dehydrogenase activity or change in the morphological signature occurred on 24 hr exposure of 3T3-L1 adipocytes to RA. These results suggest that RA can specifically down-regulate LPL enzyme expression in adipocytes at the posttranscriptional level.

Adipose Tissue↗
PubMed1991

Effect of a high-protein diet on the gene expression of a trypsin-sensitive, cholecystokinin-releasing peptide (monitor peptide) in the pancreas.

The adaptation to a high protein diet of the concentration and mRNA level of a trypsin-sensitive, cholecystokinin-releasing peptide (monitor peptide), which was proposed to be the mediator of the cholecystokinin release in response to protein intake, was investigated in the rat pancreas. Adult rats were placed on one of two isocaloric diets. One group was fed a 22% casein diet (control diet) and the other a 64% casein diet (high-protein diet) for 14 days. In order to quantify the monitor peptide separately from pancreatic secretory trypsin inhibitor (PSTI-II), which is highly similar in its amino acid and mRNA nucleotide sequences to the monitor peptide but has less cholecystokinin-releasing activity, we used specific assay methods: HPLC was used for determining the monitor peptide concentration in zymogen granules and a synthetic oligonucleotide probe for determining the mRNA of the monitor peptide in the pancreas. The concentrations in the zymogen granules and the mRNA levels in the pancreas of the two peptides increased in parallel during the adaptation to the high protein diet, indicating that these two peptides were under the same control during the adaptation. The concentration and mRNA level of the monitor peptide, which were measured after 0, 3, and 14 days, increased throughout the experiment period, as did the concentration of trypsin. This suggested that the monitor peptide and trypsin may respond to similar signals during the adaptation to a high protein diet and that this apparent coordination may facilitate the adaptation of the pancreas to the diet.

Amino Acid Sequence↗
PubMed1991

Decrease in muscle glucose transporter number in chronic physical inactivity in rats.

In this study, whole body insulin action on glucose uptake and muscle glucose transporter number of rats subjected to 14 days of physical inactivity conditions was examined. Unlike other suspension and denervation models of muscle disuse, this physical inactivity model allows voluntary contractile activity with minimal stress. Minimal depression of body weight gain and significant depression of gastrocnemius muscle growth were observed compared with that of control rats after 14 days of physical inactivity. The whole body insulin sensitivity and responsiveness were determined by the euglycemic clamp technique, with 1.4, 3.6, and 14 mU insulin.kg-1.min-1 perfusion and 2-deoxy-D-[3H]glucose incorporation. The rates of glucose disposal were the same in the restrained rats as in the controls with the 1.4 and 3.6 mU insulin perfusion; however, glucose disposal significantly decreased with 14 mU insulin perfusion. 2-Deoxy-D-[3H]glucose uptake into the gastrocnemius muscle was higher in the control rats than in the physically inactive rats. Glucose transporters in the gastrocnemius and quadriceps muscles, measured by means of the D-glucose-inhibitable cytochalasin B binding assay, were significantly decreased in number in the physically inactive rats. These findings suggest that the decrease in whole body glucose uptake might in part be explained by the decreases in the total glucose transporter number in muscles.

Adrenocorticotropic Hormone↗
PubMed1990

Protein factor obtained from rat adipose tissue specifically permits the proliferation of the 3T3-L1 and Ob1771 cell lines.

We have found the presence of protein factor in rat adipose tissue which permits the proliferation of 3T3-L1 and Ob1771 preadipocytes cultured in a completely defined serum-free medium containing only progression factors [epidermal growth factor (EGF) and insulin] as growth factors. This mitogenic activity of the protein factor was not detected in various other cell lines, in particular, Swiss 3T3 cells which could proliferate in response to a competent factor [platelet-derived growth factor (PDGF) or fibroblast growth factor (FGF)] in the same serum-free medium. This activity of the factor was heat- and pronase-unstable, and reductant-stable, and the apparent molecular weight of the factor was about 20,000. These results strongly suggest that the protein factor is different from PDGF or FGF and contributes to the formation of new adipocytes by specifically stimulating the proliferation of preadipocytes, acting like competent factor.

Adipose Tissue↗
PubMed1990

Comparative investigation of vitamins and their analogues on terminal differentiation, from preadipocytes to adipocytes, of 3T3-L1 cells.

1. The effects of 20 kinds of vitamins or their analogues on the growth rate of preadipocytes and the terminal differentiation of preadipocytes to adipocytes was systematically compared in 3T3-L1 cells. 2. The addition of vitamin C markedly increased the growth rate of preadipocytes at over 50 microM. 3. The addition of vitamin K3 slowed down the growth rate at over 0.1 microM. 4. In water soluble vitamins and their analogues tested, the vitamin B6 group and vitamin C significantly stimulated the differentiation, and consequently increased the glycerophosphate dehydrogenase activity and triglyceride accumulation, to a concentration of over 10 microM. 5. Many fat soluble vitamins and their analogues (the vitamin A group, including beta-carotene, the vitamin D group, vitamin E and the vitamin K group) strongly inhibited the adipose conversion of 3T3-L1 cells at microM level.

Adipose Tissue↗
PubMed1990

Proliferation of 3T3-L1 preadipocytes in a completely defined serum-free medium.

We have developed a completely defined serum-free medium that supports the growth of Swiss 3T3-L1 fibroblasts to nearly the same extent as Dulbecco's modified Eagle's medium supplemented with 10% fetal calf serum. With ASF301 medium [former name, RITC 80-7; Yamane et al. Exp. Cell Res. 134, 470 (1981)], most of the 3T3-L1 cells survived for at least 10 days, but did not grow. ASF301 medium contains insulin and mouse-epidermal growth factor as growth factors, which are termed "progression factors". So we examined the effects of "competent factors" on the proliferation of 3T3-L1 preadipocytes. Growth in the medium supplemented with competent factors reached a confluent monolayer in 6-7 days. Furthermore, it was confirmed that 3T3-L1 cells grown in the serum-free medium retained the properties of differentiation into adipocytes. Our serum-free medium should be a useful tool for research on the growth and differentiation of 3T3-L1 preadipocytes.

Adipose Tissue↗