Regulation and functional relevance of milk fat globules and their components in the mammary gland

Mammary gland and epithelial cells are unique to mammals and are under the control of lactogenic hormones such as prolactin. Recent findings indicated that major components of milk fat globule membrane (MFGM) are under the control of lactogenic hormones, and that the major components butyrophilin and xanthine oxidoreductase are indispensable for milk fat secretion. Further, prolactin signaling is negatively controlled by two highly related protein tyrosine phosphatases, PTP1B and TC-PTP. Milk fat globule EGF factor 8 (MFG-E8) is one of the major components of MFGM and is upregulated during lactation. MFG-E8 is further upregulated in the involuting mammary gland. MFG-E8 on exosome-like membrane vesicles in the milk recovered from post-weaning but not lactating mammary glands exhibits higher binding activity to phosphatidylserine and apoptotic mammary epithelial cells, and serves as a link between apoptotic mammary epithelial cells and phagocytes. Recent reports using MFG-E8 deficient mice support the view that MFG-E8 is indispensable for eliminating apoptotic mammary epithelial cells during involution.

Resonantly enhanced nonlinear conductance in long quantum point contacts near pinch-off

We report on a remarkable resonance in the differential conductance of long quantum point contacts (QPCs) that is observed as a precursor to regular quantized transport. This effect is increasingly pronounced in longer QPCs, in which the differential conductance may resonantly exceed 2e2/h. From a study of the experimental characteristics of this feature, we suggest that it may be associated with the formation of a well-resolved energy gap that opens dynamically as a result of enhanced many-body interactions in long QPCs.

Effects of running exercise on fibre-type distribution of soleus and plantaris muscles in diabetic Otsuka Long-Evans Tokushima fatty rats

AIM

Effect of running exercise on fibre-type distributions of the slow soleus and fast plantaris muscles was investigated in male Otsuka Long-Evans Tokushima fatty rats (OLETF) as an animal model of spontaneous type 2 diabetes mellitus.

METHODS

Five-week-old OLETF rats were allowed to exercise voluntarily in running wheels for 32 days and the data were compared with those of age-matched non-exercised OLETF and non-diabetic Long-Evans Tokushima Otsuka rats (LETO).

RESULTS

In the soleus muscle, a higher percentage of type I fibres was observed in non-exercised OLETF rats compared with LETO rats, and there were no type IIA fibres in non-exercised OLETF rats. In the plantaris muscle, a higher percentage of type IIB fibres and a lower percentage of type I and type IIA fibres were observed in non-exercised OLETF rats compared with LETO rats. In contrast, there were no differences in the fibre-type distribution of soleus and plantaris muscles between exercised OLETF and LETO rats. The body weight and type I fibre percentage of the soleus muscle were related to the running distance in exercised OLETF rats. White adipose tissue weight, HbA(1c) and blood insulin and glucose concentrations were lower in exercised OLETF rats than in non-exercised OLETF rats, irrespective of the running distance. There was a difference in the gene-expression pattern of the soleus muscle among LETO rats, non-exercised OLETF and exercised OLETF rats.

CONCLUSION

Running exercise can inhibit diabetes-associated type shifting of fibres, which is more apparent with postnatal growth, in skeletal muscles of diabetic OLETF rats, as a result of mRNA expression change in muscle.

A new simple therapeutic method for chronic subdural hematoma without irrigation and drainage

BACKGROUND

We developed a new simple therapeutic method for the treatment of chronic subdural hematoma (CSDH) without irrigation and drainage. This method is characterized by replacement of the hematoma with oxygen.

METHODS

Seventy patients (seventy-eight sides) with CSDH were treated with this method from May 1994 to October 2002. For the complete replacement of the hematoma with oxygen, subdural tapping site was changed from the thickest area of the hematoma to the parietal tuber. Irrigation and drainage were not used in all patients.

RESULTS

Neurological recovery after the treatment was satisfactory in all 70 patients. An average amount of replaced hematoma was 96.1 ml, ranging from 5 to 280 ml. An initial hematoma pressure ranged from 0 to 200 mm H2O (average: 92.1 mm H2O). During the follow up periods, clinical recurrence was noted in 7 patients (10%) and 7 sides (9.0%).

CONCLUSION

The replacement of the hematoma with oxygen via percutaneous subdural tapping without irrigation and drainage is useful and less invasive method for the treatment of CSDH.

Regulation of STAT3-mediated signaling by LMW-DSP2

Signal transducer and activator of transcription 3 (STAT3), which mediates biological actions in many physiological processes, is activated by cytokines and growth factors, and has been reported to be constitutively activated in numerous cancer cells. In this study, we examined whether low molecular weight-dual specificity phosphatase two (LMW-DSP2) is involved in the regulation of the interleukin 6 (IL-6)/leukemia inhibitory factor (LIF)/STAT3-mediated signaling pathway. IL-6/LIF-induced LMW-DSP2 expression in murine testicular or hepatoma cell lines, while LMW-DSP2 overexpression in 293T cells suppressed IL-6-induced phosphorylation and activation of STAT3. Furthermore, LMW-DSP2 suppressed the expression of IL-6-induced endogenous genes. In contrast, small-interfering RNA-mediated reduction of LMW-DSP2 expression enhanced IL-6-induced STAT3-dependent transcription. In fact, LMW-DSP2 interacted with STAT3 in vivo and endogenous LMW-DSP2 bound to STAT3 in murine testicular GC-1 cells. These results strongly suggest that LMW-DSP2 acts as a negative regulator of the IL-6/LIF/STAT3-mediated signaling pathway.

Weaning-induced expression of a milk-fat globule protein, MFG-E8, in mouse mammary glands, as demonstrated by the analyses of its mRNA, protein and phosphatidylserine-binding activity

A milk membrane glycoprotein, MFG-E8 [milk fat globule-EGF (epidermal growth factor) factor 8], is expressed abundantly in lactating mammary glands in stage- and tissue-specific manners, and has been believed to be secreted in association with milk fat globules. In the present paper, we describe further up-regulation of MFG-E8 in involuting mammary glands, where the glands undergo a substantial increase in the rate of epithelial cell apoptosis, and a possible role of MFG-E8 in mediating recognition and engulfment of apoptotic cells through its specific binding to PS (phosphatidylserine). Immunoblotting and RNA blotting analyses revealed that both MFG-E8 protein and MFG-E8 mRNA were markedly increased in mammary tissue within 3 days of either natural or forced weaning (pup withdrawal) of lactating mice. Using immunohistochemical analysis of the mammary tissue cryosections, the MFG-E8 signal was detected around the epithelium of such involuting mammary glands, but was almost undetectable at early- and mid-lactation stages, although strong signals were obtained for milk fat globules stored in the alveolar lumen. Some signals double positive to a macrophage differentiation marker, CD68, and MFG-E8 were detected in the post-weaning mammary tissue, although such double-positive signals were much smaller in number than the MFG-E8 single-positive ones. Total MFG-E8 in milk was also increased in the post-weaning mammary glands and, furthermore, the free MFG-E8 content in the post-weaning milk, as measured by in vitro PS-binding and apoptotic HC11 cell-binding activities, was much higher than that of lactation. In addition, the post-weaning milk enhanced the binding of apoptotic HC11 cells to J774 macrophages. Sucrose density-gradient ultracentrifugation analyses revealed that such enhanced PS-binding activity of MFG-E8 was present in membrane vesicle fractions (density 1.05-1.13 g/ml), rather than milk fat globule fractions. The weaning-induced MFG-E8 might play an important role in the recognition and engulfment of apoptotic epithelial cells by the neighbouring phagocytic epithelial cells in involuting mammary glands.

Comprehensive study of urinary cortisol metabolites in hyperthyroid and hypothyroid patients

OBJECTIVE

To further analyse the significance and mutual relationship of thyroid function-linked alterations in cortisol metabolism that have been separately and variously reported.

PATIENTS AND MEASUREMENTS

Twenty-four-hour urine samples from 21 patients with hyperthyroidism (Graves' disease), 16 patients with hypothyroidism (Hashimoto's thyroiditis), 21 healthy age- and sex-matched controls for hyperthyroidism, and 16 healthy age- and sex-matched controls for hypothyroidism were evaluated for 6beta-hydroxycortisol (6beta-OHF), tetrahydrocortisol (THF), tetrahydrocortisone (THE), allo-tetrahydrocortisol (allo-THF), urinary free cortisol (UFF), urinary free cortisone (UFE) and 17-hydroxycorticosteroid (17-OHCS).

RESULTS

Urinary 17-OHCS, THE and allo-THF levels increased considerably in hyperthyroid patients compared to the controls, while UFF and THF showed no difference between the two groups. Urinary 6beta-OHF was significantly lower in the hyperthyroid patients than in the controls. Both the urinary allo-THF + THF/THE and the UFF/UFE ratios were significantly lower in the hyperthyroid patients than in the controls, whereas only the former was significantly higher in the hypothyroid patients than in the controls. The urinary allo-THF/THF ratio was significantly higher in the hyperthyroid patients and significantly lower in the hypothyroid patients than in the controls. In an analysis of pooled subjects including all groups (n = 64), free T4 levels correlated negatively (P < 0.0001) with the urinary allo-THF + THF/THE ratio but not with the UFF/UFE ratio. The serum levels of free T4 correlated positively (P < 0.0001) with the urinary allo-THF/THF ratio.

CONCLUSION

The thyroid hormones seem to affect the total 11beta-HSD activity (allo-THF + THF/THE) more strongly than the renal 11beta-HSD2 activity (UFF/UFE). 5alpha-reductase activity (allo-THF/THF) is also enhanced in hyperthyroidism, while the reduction of urinary 6beta-OHF in hyperthyroidism might be a secondary effect of the altered activity of the total 11beta-HSD and 5alpha-reductase.

The wide distribution of endornaviruses, large double-stranded RNA replicons with plasmid-like properties

The International Committee on Taxonomy of Viruses (ICTV) recently accepted Endornavirus as a new genus of plant dsRNA virus. We have determined the partial nucleotide sequences of the RNA-dependent RNA polymerase regions from the large dsRNAs (about 14 kbp) isolated from barley (Hordeum vulgare), kidney bean (Phaseolus vulgaris), melon (Cucumis melo), bottle gourd (Lagenaria siceraria), Malabar spinach (Basella alba), seagrass (Zostera marina), and the fungus Helicobasidium mompa. Phylogenetic analyses of these seven dsRNAs indicate that these dsRNAs are new members of the genus Endornavirus that are widely distributed over the plant and fungal kingdoms.

A newly identified zona pellucida glycoprotein, ZPD, and dimeric ZP1 of chicken egg envelope are involved in sperm activation on sperm-egg interaction

Fertilization begins with interaction between the sperm and the egg. The surface of the vertebrate oocyte is covered with the egg envelope, which is composed of ZP (zona pellucida) glycoproteins. We have identified two glycoproteins, ZP1/gp97 and ZPC/gp42, as the major components of the chicken egg envelope. In the present study, another 42 kDa protein, designated ZPD, has been found as a new major component of the chicken egg envelope. ZPD was specifically released from the egg envelope by ultrasonication treatment without urea. ZPD cDNA was cloned using a chicken granulosa cell cDNA pool. The deduced amino acid sequence showed that preproprotein of ZPD is composed of 418 amino acid residues with four potential N-glycosylation sites and includes a ZP domain, common in vertebrate ZP glycoproteins, and a transmembrane domain. ZPD belongs phylogenetically to a distinct group from known ZP glycoprotein subfamilies, ZPA, ZPB, and ZPC. In two-dimensional gel electrophoresis ZPD proteins were identified to be several isoforms with different pI values between 5 and 7. ZP1, ZPC and the newly identified ZPD were confirmed to be the major components of chicken egg envelope by MS of proteolytic digests of whole egg envelope. The in vitro incubation of chicken sperm with calcium ionophore A23187 induced sperm activation, resulting in the fragmentation and release of a 41 kDa PNA (peanut agglutinin)-positive glycoprotein and the decrease or loss of sperm PNA-stainability. The incubation with ZPD and dimeric ZP1, but not ZPC and monomeric ZP1, also induced the decrease or loss of sperm PNA-stainability, suggesting the in vitro sperm activation by these ZP components. Collectively, ZPD might bind loosely to egg envelope matrix and play a key role in the sperm activation on avian sperm-egg interaction.

Receptor-Type Protein Tyrosine Phosphatase ε (PTPεM) is a Negative Regulator of Insulin Signaling in Primary Hepatocytes and Liver

Impaired insulin receptor (IR) signaling leads to insulin resistance and type 2 diabetes mellitus. Several inhibitors of the IR tyrosine kinase activity have recently been described and associated with human insulin resistance. Among these negative regulators, protein tyrosine phosphatases (PTPs) are likely to play a pivotal role in IR signaling. Transgenic studies revealed that PTP1B and TCPTP are primary candidates but IR of these animals can be finally dephosphorylated, suggesting that other PTPs are also involved in the dephosphorylation of IR. In this study, we showed that receptor-type PTPepsilon (PTP epsilonM) dephosphorylated IR in rat primary hepatocytes and tyrosines 972, 1158, 1162 and 1163 were primary targets of PTP epsilonM. Wild type as well as substrate-trapping DA forms of PTPepsilonM suppressed phosphorylation of IR downstream enzymes such as Akt, extracellular regulated kinase (ERK) and glycogen synthase kinase 3 (GSK3). It was also demonstrated that PTPepsilonM suppressed insulin-induced glycogen synthesis and inhibited insulin-induced suppression of phosphoenol pyruvate carboxykinase (PEPCK) expression in primary hepatocytes. Furthermore, adenovirally introduced PTPepsilonM also exhibited inhibitory activity against suppression of PEPCK expression in mouse liver. These results suggest that PTPepsilonM is a negative regulator of IR signaling and involved in insulin-induced glucose metabolism mainly through direct dephosphorylation and inactivation of IR in hepatocytes and liver.

Rapid adsorption pretreatment with submicrometre powdered activated carbon particles before microfiltration

Manufacturer-supplied powdered activated carbon (PAC) was ground to produce submicrometre particles (0.8 and 0.6 m median diameter) for use as an adsorbent before microfiltration (MF) for drinking water treatment. Batch tests revealed that the microground PAC adsorbed natural organic matter (NOM) much more rapidly and had a higher adsorptive capacity than ordinary PAC. The water samples pretreated with the submicrometre PAC were subjected to MF, and the results of experiments with different PAC contact times revealed that a 1 min retention time was sufficient for adsorptive removal of NOM. The use of submicrometre PAC permitted not only shorter PAC contact times but also a 75% reduction in dose.

Study on anti-androgenic effects of bisphenol a diglycidyl ether (BADGE), bisphenol F diglycidyl ether (BFDGE) and their derivatives using cells stably transfected with human androgen receptor, AR-EcoScreen

We studied in vitro hormonal activity of bisphenol A diglycidyl ether (BADGE) and bisphenol F diglycidyl ether (BFDGE), which are used as a material of interior coating for food cans. We also examined related compounds such as 2,2-bis[4-(3-chloro-2-hydroxypropoxy)phenyl]propane (BADGE.2HCl), and bis[4-(3-chloro-2-hydroxypropoxy)phenyl]methane (BFDGE.2HCl) etc. For this purpose, we constructed two stably transfected CHO-K1 cell lines (AR-EcoScreen for androgenic activity and c-luc for cell toxicity evaluation). One stably expresses luciferase with induction of androgen. The other stably expresses luciferase without androgen induction. Also, we have determined the androgenic and anti-androgenic effects of the test chemicals by reporter gene assay with these cell lines. None of the chemicals tested by this assay exhibited androgen agonistic activity. However, BADGE.2HCl and BFDGE.2HCl had the conspicuous antagonistic activity for androgen. These compounds had a high binding affinity for androgen receptor. Furthermore, these two compounds did not show the estrogenic activity in vitro assays. On the contrary, bisphenol A and bisphenol F exhibited anti-androgenic activity in vitro in addition to the estrogenic activity. These results suggest that these chlorohydroxy compounds of BADGE and BFDGE act as androgen antagonist through the process of binding to androgen receptor.

Expression and localisation analysis of the wheat sucrose transporter TaSUT1 in vegetative tissues

Previously we reported the isolation of three sucrose transporter genes, TaSUT1A, 1B and 1D, all expressed at high levels in the developing grains of hexaploid wheat ( Triticum aestivum L.), but also in a variety of other tissues. In order to further characterise the expression of the TaSUT1 genes in wheat plants, we have analysed TaSUT1 expression in their vegetative tissues using semi-quantitative reverse transcription-polymerase chain reaction, in situ hybridisation and immunolocalisation. The three TaSUT1 genes, which encode 98% identical SUT proteins, all appeared to be expressed at the same level in leaf blades, leaf sheaths and internodes, as well as developing grains, of hexaploid wheat. In mature leaf blades, TaSUT1 protein localised to the plasma membrane of phloem sieve elements in all classes of veins. In contrast, TaSUT1 mRNA was found to be localised to phloem companion cells. A similar localisation pattern for TaSUT1 protein was observed in veins of leaf sheaths and internodes. These results suggest that the wheat SUT1 has a transport function in enucleate sieve elements, in both veins responsible for loading photoassimilates, and in veins for axial transport. Furthermore, transport of the fluorescent dye carboxyfluorescein was used to investigate symplasmic connectivity between sieve element-companion cell complexes and non-phloem cells. Observations in source leaves indicated that sieve element-companion cell complexes of minor veins were symplasmically restricted, suggesting a role of TaSUT1 in apoplasmic phloem loading. In contrast, the dye was able to move symplasmically out of the phloem in internodes. In these circumstances TaSUT1 may also have a role in retrieving sucrose leaked to the phloem apoplasm.

Mutual regulation of protein-tyrosine phosphatase 20 and protein-tyrosine kinase Tec activities by tyrosine phosphorylation and dephosphorylation

PTP20, also known as HSCF/protein-tyrosine phosphatase K1/fetal liver phosphatase 1/brain-derived phosphatase 1, is a cytosolic protein-tyrosine phosphatase with currently unknown biological relevance. We have identified that the nonreceptor protein-tyrosine kinase Tec-phosphorylated PTP20 on tyrosines and co-immunoprecipitated with the phosphatase in a phosphotyrosine-dependent manner. The interaction between the two proteins involved the Tec SH2 domain and the C-terminal tyrosine residues Tyr-281, Tyr-303, Tyr-354, and Tyr-381 of PTP20, which were also necessary for tyrosine phosphorylation/dephosphorylation. Association between endogenous PTP20 and Tec was also tyrosine phosphorylation-dependent in the immature B cell line Ramos. Finally, the Tyr-281 residue of PTP20 was shown to be critical for deactivating Tec in Ramos cells upon B cell receptor ligation as well as dephosphorylation and deactivation of Tec and PTP20 itself in transfected COS7 cells. Taken together, PTP20 appears to play a negative role in Tec-mediated signaling, and Tec-PTP20 interaction might represent a negative feedback mechanism.

Protein tyrosine phosphatase PTP20 induces actin cytoskeleton reorganization by dephosphorylating p190 RhoGAP in rat ovarian granulosa cells stimulated with follicle-stimulating hormone

We identified 25 protein tyrosine phosphatases (PTPs) expressed in rat ovarian granulosa cells. Of these PTPs, the expression levels of at least PTP20, PTP-MEG1, PTPepsilonM, and PTPepsilonC significantly changed during the estrous cycle. We examined the cellular functions of PTP20 in granulosa cells by expressing the wild type, a catalytically inactive CS mutant in which Cys229 of PTP20 was changed to Ser, or a substrate-trapping DA mutant in which Asp197 was mutated to Ala, using an adenovirus vector. Overexpression of the wild type, but not of the CS mutant, induced retraction of the cell body with the extension of long, dendritic-like processes after stimulation with FSH, a critical factor for the survival and differentiation of these cells. In addition, cell adhesion to the substratum decreased in an FSH-dependent manner. Inhibiting Rho GTPase activity with C3 botulinum toxin caused similar morphological changes. The FSH-enhanced phosphotyrosine (p-Tyr) level of p190 RhoGAP was selectively reduced by the overexpressed wild type, but not by mutated PTP20. Although p190 RhoGAP is tyrosine phosphorylated by c-Src via the tyrosine kinase Pyk2, wild-type PTP20 had little effect on p-Tyr418 of c-Src and no effect on p-Tyr402 of Pyk2, which are required for full c-Src activity and for interacting between Pyk2 and c-Src, respectively. The CS and DA mutants as well as the wild type reduced the formation of p190 RhoGAP-p120 RasGAP complexes. Confocal microscopy analysis revealed that PTP20 intracellularly colocalizes with p190 RhoGAP. These results demonstrate that PTP20 regulates the functions of granulosa cells in an FSH-dependent manner by dephosphorylating p190 RhoGAP and subsequently inducing reorganization of the actin cytoskeleton. Moreover, our data suggest that PTPs play significant roles in controlling the dynamics of ovarian functions.

Hematological alterations in the Otsuka Long-Evans Tokushima fatty (OLETF) rats--a model of type 2 diabetes mellitus

The OLETF rat develops microangiopathic complications similar to human diabetes and is considered a useful model of Type 2 DM. Erythrocyte, platelet and leucocyte abnormalities described in diabetic patients are thought to play a role in the development of diabetic microangiopathy. This study was designed to investigate whether OLETF rats show hematological alterations and the effect of sucrose treatment on metabolic and blood parameters. Hematological parameters, body weight, food and water intake, fasting and non-fasting blood glucose (BG) and HbA1c were measured in OLETF rats treated for two months with 30% sucrose added to drinking water. Non-treated OLETF rats and non-diabetic Long-Evans Tokushima Otsuka (LETO) rats were used as controls. In the control OLETF rats the number of platelets (Plt) and red blood cells (RBC) was higher, while the mean cell volume (MCV) and the mean cell hemoglobin content (MCH) were lower compared with LETO. Mean cell hemoglobin concentration (MCHC) was significantly higher in the diabetic rats. Sucrose administration decreased food intake and body weight and increased fasting blood glucose and HbA1c. It resulted in a decrease of RBC, Hb, Hct, MCV and MCH compared with control OLETF, while Plt count increased significantly. Our results point to significant alterations in erythrocyte count and morphology and Plt count in diabetic OLETF rats compared with non-diabetic LETO. Sucrose administration accelerated the development of diabetes, affected blood cells inducing the suppression of RBC and an increase in Plt count and some of its effects persisted after sucrose withdrawal.

The nuclear isoform of protein-tyrosine phosphatase TC-PTP regulates interleukin-6-mediated signaling pathway through STAT3 dephosphorylation

In the previous study, we demonstrated that the nuclear isoform of T-cell protein-tyrosine phosphatase (TC-PTP) dephosphorylated and deactivated signal transducer and activator of transcription 5a (STAT5a) and STAT5b, thereby negatively regulating prolactin (PRL)-mediated signaling pathway. In this study, we examined the involvement of the nuclear isoform of TC-PTP in interleukin-6 (IL-6)-mediated signaling pathway. IL-6 is a multifunctional cytokine that plays important roles in the immune system, hematopoiesis, and acute phase reactions, and has also implicated in IL-6-related diseases. Here, we demonstrate that IL-6-induced tyrosine-phosphorylation and activation of STAT3 were suppressed by overexpression of the nuclear isoform of TC-PTP in 293T cells. Tyrosine-phosphorylated STAT3 directly interacted with a substrate-trapping mutant of TC-PTP. Furthermore, retrovirus-mediated overexpression of the nuclear isoform of TC-PTP suppressed the IL-6-induced growth arrest of myeloid leukemia M1 cells. Endogenous TC-PTP complexed with STAT3 in the nucleus of M1 cells. These results strongly suggest that the nuclear isoform of TC-PTP may serve as a negative regulator of IL-6-mediated signaling pathway.

Inhibition of aromatase activity by green tea extract catechins and their endocrinological effects of oral administration in rats

We orally administered polyphenone-60 (P-60), green tea extract catechins, in the diet (0, 1.25 and 5%) to male rats for 2, 4 and 8 weeks initiated at 5 weeks old. It was found that a 5% dose to male rats for 2-8 weeks induced goiters and decreased weights of the body, testis and prostate gland. Endocrinologically, elevating plasma thyroid stimulating hormone (TSH), luteinizing hormone (LH) and testosterone levels and decreasing tri-iodothyronine (T(3)) and thyroxine (T(4)) levels were induced by this treatment. We also found that P-60 as a whole and some of its constituents exhibited inhibitory effects on human placental aromatase activity by in vitro assay. The concentration of P-60 that required producing 50% inhibition of the aromatase activity (IC(50) value) was 28 microg/ml. The IC(50) values of (-)-catechin gallate (Cg), (-)-epigallocatechin (EGC), (-)-epigallocatechin gallate (EGCg) and (-)-gallocatechin gallate (GCg) were 5.5 x 10(-6), 1.0 x 10(-4), 6.0 x 10(-5) and 1.5 x 10(-5) M, respectively. (-)- Epicatechin gallate (ECg) at 1.0 x 10(-4) M produced 20% inhibition. (-)-Epicatechin (EC) and (+)-catechin (CT) exhibited no effects on aromatase activity. The endocrinological changes observed in vivo were in conformity with antithyroid effects and aromatase inhibition effects of P-60 and its constituents.

Overexpression and ribozyme-mediated targeting of transcriptional coactivators CREB-binding protein and p300 revealed their indispensable roles in adipocyte differentiation through the regulation of peroxisome proliferator-activated receptor gamma

The cAMP-response element-binding protein-binding protein (CBP) and p300 are common coactivators for several transcriptional factors. It has been reported that both CBP and p300 are significant for the activation of peroxisome proliferator-activated receptor gamma (PPARgamma), which is a crucial nuclear receptor in adipogenesis. However, it remains unclear whether CBP and/or p300 is physiologically essential to the activation of PPARgamma in adipocytes and adipocyte differentiation. In this study, we investigated the physiological significance of CBP/p300 in NIH3T3 cells transiently expressing PPARgamma and CBP and in 3T3-L1 preadipocytes stably expressing CBP- or p300-specific ribozymes. In PPARgamma-transfected NIH3T3 cells, induction of expression of PPARgamma target genes such as adipocyte fatty acid-binding protein (aP2) and lipoprotein lipase (LPL) by adding thiazolidinedione was enhanced, depending on the amount of a CBP expression plasmid transfected. Expression of aP2 and LPL genes, as well as glycerol-3-phosphate dehydrogenase activity and triacylglyceride accumulation after adipogenic induction, was largely suppressed in 3T3-L1 adipocytes expressing either the CBP- or p300-specific active ribozyme, but not in inactive ribozyme-expressing cells. These data suggest that both CBP and p300 are indispensable for the full activation of PPARgamma and adipocyte differentiation and that CBP and p300 do not mutually complement in the process.