[Progress in studies of endocrinology and metabolism in the field of internal medicine in the last 100 years: Obesity and adipocytes].
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Adipocytes↗
Biomedical subjects
Yuji Matsuzawa
Publications and source records attributed to Yuji Matsuzawa.
Increased plasma HB-EGF associated with obesity and coronary artery disease.
The mechanism by which the obese subjects are more associated with vascular disease remains unclear. We reported that the adipose tissues produce and secrete many bioactive molecules, conceptualized as adipocytokines. Heparin-binding epidermal growth factor (EGF)-like growth factor (HB-EGF), produced locally by vascular macrophages and smooth muscle cells, has been suggested to induce the migration and proliferation of vascular smooth muscle cells. The current study reveals that (1) HB-EGF mRNA is abundantly expressed in human adipose tissue, (2) HB-EGF mRNA increases in the fat tissues of obese mice, (3) plasma HB-EGF levels increase in parallel with fat accumulation in human, and (4) the subjects with coronary artery disease have higher plasma HB-EGF levels, associated with fat accumulation. These results suggest that increased plasma HB-EGF derived from the accumulated fat contributes to the higher incidence of vascular disease in obesity, proposing HB-EGF as an adipocytokine directly linking adipovascular axis.
Adipose Tissue↗
Dose-dependent and time-limited proliferation of cultured murine interstitial cells of Cajal in response to stem cell factor.
Interstitial cells of Cajal (ICCs) play a role as pacemakers for gastrointestinal movement. Although some in vivo experiments showed that the c-kit receptor tyrosine kinase (KIT) and its ligand, stem cell factor (SCF), might be required for the development of murine ICCs near birth, in vitro experiments would be useful to clarify the role of SCF-KIT system for the development of ICCs. We attempted to establish a culture system in order to investigate the proliferation of ICCs. Murine gastrointestinal cells from embryos or neonates were cultured with SCF and stained with anti-KIT antibody and/or alcian-blue. The numbers of KIT+ cells a n d alcian-blue+ cells we re counted, and the number of KIT+.alcian-blue- cells, which represent ICCs was calculated. Clusters containing KIT+ cells were formed in culture. The number of KIT+.alcian-blue- cells from day-18 post coitum embryos increased in response to SCF up to a concentration of 50 ng/ml or for 8 days. The number of cells from day-2 post-partum neonates increased for 4 days, and then remained constant in the presence of SCF. In contrast, the number of cells from day-6 post-partum neonates did not increase and remained constant, even in the presence of SCF. ICCs showed a dose-dependent and time-limited proliferation in response to SCF in the in vitro culture system used here in.
Alcian Blue↗
Frequent impairment of the spindle assembly checkpoint in hepatocellular carcinoma.
BACKGROUND: Chromosomal instability (CI) leading to aneuploidy is one form of genetic instability, a characteristic feature of various types of cancers. Recent work has suggested that CI can be induced by a spindle assembly checkpoint defect. The aim of the current study was to determine the frequency of a defect of the checkpoint in hepatocellular carcinoma (HCC) and to establish whether alterations of genes encoding the checkpoint were associated with CI in HCC. METHODS: Aneuploidy and the function of the spindle assembly checkpoint were examined using DNA flow cytometry and morphologic analysis with microtubule disrupting drugs. To explore the molecular basis, the authors examined the expression and alterations of the mitotic checkpoint gene, BUB1, using Northern hybridization and direct sequencing in 8 HCC cell lines and 50 HCC specimens. Furthermore, the authors examined the alterations of other mitotic checkpoint genes, BUBR1, BUB3, MAD2B, and CDC20, using direct sequencing in HCC cell lines with aneuploidy. RESULTS: An impaired spindle assembly checkpoint was found in five (62.5%) of the eight aneuploid cell lines. Transcriptional expressions of the BUB1 gene appeared in all cell lines. While some polymorphic base changes were noted in BUB1, BUBR1, and CDC20, no mutations responsible for impairment of the mitotic checkpoint were found in either the HCC cell lines or HCC specimens, which suggests that these genes did not seem to be involved in tumor development in HCC. CONCLUSIONS: The loss of spindle assembly checkpoint occurred with a high frequency in HCC with CI. However, other mechanisms might also contribute to CI in HCC.
Adult↗
Significance of the association between heparin-binding epidermal growth factor-like growth factor and CD9 in human gastric cancer.
Heparin-binding epidermal growth factor-like growth factor (HB-EGF) is a member of the EGF family. Juxtacrine activity of proHB-EGF (the membrane-anchored form of HB-EGF) has been shown to be significantly potentiated when it is coexpressed with CD9 in vitro. The purpose of our study was to investigate the issue of whether proHB-EGF and CD9 are coexpressed in gastric cancer. HB-EGF gene expression and protein production in human gastric cancers was investigated, and EGF receptor and CD9 expressions were also evaluated. HB-EGF mRNA levels in gastric cancers were elevated, compared with normal gastric tissues, especially in the intestinal type. ProHB-EGF immunoreactivity was detected primarily in the cytoplasm and plasma membrane of gastric cancer cells. Of 66 patients, 40 (60.6%) exhibited proHB-EGF immunoreactivity and the level of its expression was significantly associated with tumor status (p < 0.01) and histological differentiation (p < 0.001). In addition, proHB-EGF mRNA was detected at high levels in the intestinal type by in situ hybridization. CD9 immunoreactivity was found to be preserved in 26 of 36 patients (72.2%) and CD9 protein expression was inversely associated with lymph node status (p < 0.05). A significant correlation between its expression and histological differentiation (p < 0.01) was found, and the association of CD9 with proHB-EGF was increased in the intestinal type, as evidenced by an immunoprecipitation method. These results indicate that the coexpression of proHB-EGF and CD9 may be involved in the tumorigenesis and/or proliferation of gastric cancers in a juxtacrine manner.
Adult↗
Interaction between Src homology 2 domain bearing protein tyrosine phosphatase substrate-1 and CD47 mediates the adhesion of human B lymphocytes to nonactivated endothelial cells.
CD47 modulates a variety of cell functions such as adhesion, spreading, and migration. Using a fusion protein consisting of the extracellular region of Src homology 2 domain bearing protein tyrosine phosphatase substrate-1 (SHPS-1) and the Fc portion of human Ig (SHPS-1-Ig) we investigated the effects of SHPS-1 as a ligand for CD47 on B lymphocytes. Although SHPS-1-Ig binding to human B cell lines was solely mediated via CD47, their binding capacity for soluble and immobilized SHPS-1-Ig varied among cell lines irrespective of the similar expression levels of CD47, suggesting that distinctive affinity/avidity states exist during B cell maturation. Nalm6 cell line and tonsilar B lymphocytes adhered to immobilized SHPS-1-Ig and showed polarization-like morphology. These effects of SHPS-1-Ig were blocked by anti-CD47 mAbs (B6H12 and SE5A5). Wortmannin, a phosphatidylinositol-3 kinase inhibitor, but not pertussis toxin significantly inhibited the polarization induced by the immobilized SHPS-1-Ig. Thus, SHPS-1 acts as an adhesive substrate via CD47 in human B lymphocyte. Immunohistochemical analyses indicated that SHPS-1 is expressed on high endothelial venule as well as macrophages in human tonsils. HUVECs also express SHPS-1 in the absence of any stimuli, and the adhesion of tonsilar B lymphocytes to nonactivated HUVECs was significantly inhibited by SE5A5, indicating that SHPS-1/CD47 interaction is involved in the adhesion. Our findings suggest that SHPS-1/CD47 interaction may contribute to the recruitment of B lymphocytes via endothelial cells under steady state conditions.
Antibodies, Monoclonal↗
Peroxisome proliferator-activated receptor gamma reduces the growth rate of pancreatic cancer cells through the reduction of cyclin D1.
Peroxisome proliferator-activated receptor gamma (PPARgamma) forms a heterodimeric DNA-binding complex with the retinoid X receptor (RXR) and regulates the transcription of its target genes. Activation of PPARgamma has been shown to induce G1 arrest and to inhibit cell growth of human pancreatic carcinoma cell lines. The purpose of the present study was to examine the effect of ligand activation of PPARgamma and RXR on cell growth and on the expression of G1 cyclins in a pancreatic cancer cell line PANC-1, which expresses PPARgamma at high levels. Troglitazone, a specific ligand for PPARgamma, was found to cause a reduction in the growth rate and induced G1 cell cycle arrest and this effect was additive with that of 9-cis retinoic acid (9-cis RA), a ligand for RXR. Of the G1 cyclins tested, troglitazone specifically reduced the expression of cyclin D1 mRNA and the corresponding protein and this effect was also additive with 9-cis RA. These results suggest that the activation of PPARgamma together with RXR may be useful for the suppression of pancreatic cancer cell growth through the reduction in cyclin D1 levels.
Alitretinoin↗
Missense mutations in the beta(3) subunit have a different impact on the expression and function between alpha(IIb)beta(3) and alpha(v)beta(3).
Alpha(IIb)beta(3) and alpha(v)beta(3) belong to the beta(3) integrin subfamily. Although the beta(3) subunit is a key regulator for the biosynthesis of beta(3) integrins, it remains obscure whether missense mutations in beta(3) may induce the same defects in both alpha(IIb)beta(3) and alpha(v)beta(3). In this study, it is revealed that thrombasthenic platelets with a His280Pro mutation in beta(3), which is prevalent in Japanese patients with Glanzmann thrombasthenia, did contain significant amounts of alpha(v)beta(3) (about 50% of control) using sensitive enzyme-linked immunosorbent assay. Expression studies showed that the His280Probeta(3) mutation impaired alpha(IIb)beta(3) expression but not alpha(v)beta(3) expression in 293 cells. To extend these findings, the effects of several beta(3) missense mutations leading to an impaired alpha(IIb)beta(3) expression on alpha(v)beta(3) function as well as expression was examined: Leu117Trp, Ser162Leu, Arg216Gln, Cys374Tyr, and a newly created Arg216Gln/Leu292Ser mutation. Leu117Trp and Cys374Tyr beta(3) mutations did impair alpha(v)beta(3) expression, while Ser162Leu, Arg216Gln, and Arg216Gln/Leu292Ser mutations did not. With regard to ligand binding function, Ser162Leu mutation induced especially distinct effects between 2 beta(3) integrins: it markedly impaired ligand binding to alpha(IIb)beta(3) but not to alpha(v)beta(3) at all. These data clearly demonstrate that the biosynthesis and the ligand binding function of alpha(IIb)beta(3) and those of alpha(v)beta(3) are regulated in part by different mechanisms. Present data would be a clue to elucidate the regulatory mechanism of expression and function of beta(3) integrins.
Adult↗
Expression and functional analyses of novel mutations of ATP-binding cassette transporter-1 in Japanese patients with high-density lipoprotein deficiency.
ATP-binding cassette transporter-1 (ABCA1) gene is mutated in patients with familial high-density lipoprotein deficiency (FHD). In order to know the molecular basis for FHD, we characterized three different ABCA1 mutations associated with FHD (G1158A/A255T, C5946T/R1851X, and A5226G/N1611D) with respect to their expression in the passaged fibroblasts from the patients and in the cells transfected with the mutated cDNAs. Fibroblasts from the all patients showed markedly decreased cholesterol efflux to apolipoprotein (apo)-Al. In the fibroblasts homozygous for G1158A/A255T, the immunoreactive mass of ABCA1 could not be detected, even when stimulated by 9-cis-retinoic acid and 22-R-hydroxycholesterol. In the fibroblasts homozygous for C5946T/R1851X, ABCA1 mRNA was comparable. Because the mutant ABCA1 protein (R1851X) was predicted to lack the epitope for the antibody used, we transfected FLAG-tagged truncated mutant (R1851X/ABCA1-FLAG) cDNA into Cos-7 cells, showing that the mutant protein expression was markedly reduced. The expression of N1611D ABCA1 protein was comparable in both fibroblasts and overexpressing cells, although cholesterol efflux from the cells was markedly reduced. These data indicated that, in the three patients investigated, the abnormalities and dysfunction of ABCA1 occurred at the different levels, providing important information about the expression, regulation, and function of ABCA1.
ATP Binding Cassette Transporter 1↗
Metabolic consequence of long-term exposure of pancreatic beta cells to free fatty acid with special reference to glucose insensitivity.
Long-term exposure of the pancreatic beta cells to free fatty acid (FFA) reportedly inhibits glucose-stimulated insulin secretion. We here studied the impact of FFA on glucose and lipid metabolism in pancreatic beta cells with special reference to insulin secretion. Pancreatic beta-cell line MIN6 was exposed to various concentrations of palmitate for 3 days. Glucose-stimulated insulin secretion and insulin content were decreased corresponding to the concentration of the palmitate exposed. Glycolytic flux and ATP synthesis was unchanged, but pyruvate-stimulated change in NAD(P)H concentration was decreased. Pyruvate carboxylase was decreased at the protein level, which was restored by the removal of palmitate or the inhibition of beta-oxidation. Intracellular content of triglyceride and FFA were elevated, beta-oxidation was increased, and de novo lipogenesis from glucose was decreased. NADPH content and citrate output into the medium, which reflected pyruvate malate shuttle flux, were decreased, but malic enzyme activity was unaffected. The malic enzyme inhibitor alone inhibited insulin response to glucose. In conclusion, long-term exposure of FFA to beta cells inhibits glucose-stimulated insulin secretion via the decreased NADPH contents due to the inhibition of pyruvate carboxylase and malate pyruvate shuttle flux.
Animals↗
Human herpesvirus 6 meningoencephalitis successfully treated with ganciclovir in a patient who underwent allogeneic bone marrow transplantation from an HLA-identical sibling.
Human herpesvirus 6 (HHV-6) has recently been recognized as an important pathogen in immunocompromised hosts, such as patients who have undergone allogeneic bone marrow transplantation (allo-BMT). Here we report a case of HHV-6 meningoencephalitis in a patient who underwent allo-BMT from an HLA-identical sibling. The patient suffered from headache, high fever, tremor, and disorientation on day 35 after allo-BMT. Findings at magnetic resonance imaging, electroencephalography, and routine cerebrospinal fluid (CSF) examination suggested the presence of viral meningoencephalitis. We diagnosed HHV-6 meningoencephalitis by means of polymerase chain reaction (PCR) analysis of a CSF specimen. Successful treatment was achieved with ganciclovir. Because HHV-6 encephalitis has a potentially fatal and fulminant course, it is necessary that HHV-6 encephalitis be recognized as one of the central nervous system complications that can follow allo-BMT. PCR analysis for HHV-6 in the CSF specimen is necessary for appropriate diagnosis and treatment.
Adult↗
Possible relationship between deficiency of interstitial cells of Cajal and colonic inertia in a patient with colon malfixation.
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Colon↗
Epidermal growth factor inhibits the growth of TE8 esophageal cancer cells through the activation of STAT1.
BACKGROUND: Epidermal growth factor receptors (EGFRs) mediate growth signals in a variety of normal and malignant cells. However, the issue of whether the EGF/EGFR system contributes to the progression of esophageal cancer cells remains controversial. The aim of the present study was to determine the role of EGFR in the growth of esophageal cancer cell lines. METHODS: Three esophageal cancer cell lines, TE1, TE2, and TE8, were stimulated with EGF, and cellular growth was then evaluated by cell number. The activation of signal transducers and activators of transcription (STATs) and the expression of the cyclin-dependent kinase (CDK) inhibitor p21/WAF1 were determined by an electromobility shift assay and Northern blot analysis, respectively. RESULTS: EGF inhibited the growth of TE8 cells, while no significant effects were observed for TE1 and TE2 cells. The treatment of TE8 cells with EGF induced the activation of STAT1 and STAT3, followed by the expression of p21/WAF1. The introduction of a dominant-negative STAT1 construct into TE8 cells abolished not only growth inhibition but also p21/WAF1 induction by EGF. CONCLUSIONS: The findings herein suggest that EGF inhibits the growth of some esophageal cancer cells that overexpress EGFR and that the activation of STAT1 constitutes a critical event which is required for the inhibition of growth by EGF.
Blotting, Northern↗
Large scale isolation of non-uniform shear stress-responsive genes from cultured human endothelial cells through the preparation of a subtracted cDNA library.
To investigate the molecular mechanisms responsible for the regional selectivity of early atherogenesis, we have applied a non-uniform shear stress to cultured human umbilical vein endothelial cells (HUVEC). We used a microcarrier culture system and a combination of subtraction and reverse-subtraction methods to isolate a number of genes upregulated by shear stress. The resultant subtracted library includes several known genes (e.g. MCP-1, TM) whose responsiveness to shear stress has been previously reported, indicating that the library is enriched for genes upregulated by shear stress. Also included are atherosclerosis-related genes (e.g. CTGF, IL-8) whose responsiveness to shear stress had not been demonstrated, other known genes whose relationship to atherosclerosis had not been reported, and novel genes. Some responsive to centrifugal force and shear stress (RECS) genes are also upregulated following stimulation by steady laminar shear stress in a parallel plate chamber. Interestingly, the library includes ET-1 and PAI, which are well known atherogenic factors that are downregulated by laminar shear stress. This implies that turbulent shear stress has effects on HUVEC that are different from those elicited by laminar shear stress. Importantly, analysis of specimens taken from human aorta showed that several RECS genes are transcriptionally upregulated in atherosclerotic lesions, suggesting that the subtracted library includes novel therapeutic targets for the treatment of atherosclerosis.
Aorta↗
Decreased microsomal triglyceride transfer protein activity contributes to initiation of alcoholic liver steatosis in rats.
BACKGROUND/AIMS: To elucidate the role of microsomal triglyceride transfer protein (MTP) in the pathogenesis of alcoholic fatty liver, the effects of ethanol on MTP activity and gene expression were investigated. METHODS AND RESULTS: Male Sprague-Dawley rats fed an ethanol-containing liquid diet for 37 days, respectively, showed 2.9- and 4.9-fold increases in hepatic cholesterol and triglyceride content in comparison with rats fed an isocaloric ethanol-free diet (P<0.01). Furthermore, a significant decrease in MTP activity and mRNA expression (by 27 and 58%, respectively) was observed after ethanol administration. Intravenous injection of human recombinant hepatocyte growth factor (hrHGF) on each of the last 7 days markedly suppressed ethanol-induced lipid accumulation in the liver. This inhibition of fatty change by hrHGF was accompanied by recovery of MTP activity and gene expression. No inhibitory effect of hrHGF on ethanol-induced acyl-CoA synthetase activation was observed. Experiments using human hepatoma-derived HepG2 cells indicated a direct positive effect of hrHGF on MTP gene expression as well as apolipoprotein B secretion. CONCLUSIONS: These results suggest that reduced MTP activity is crucial to development of alcoholic fatty liver, while promotion of MTP activity by HGF might serve as a therapeutic measure against alcoholic liver steatosis.
Animals↗
Activation of signal transducer and activator transcription 3 and expression of suppressor of cytokine signal 1 during liver regeneration in rats.
BACKGROUND/AIMS: Recent work has shown that the signal transducer and activator of transcription (STAT) 3 activation is important for the initiation of the proliferative response following partial hepatectomy (PH). However, the issue of where STAT3 is activated and how it is regulated is unclear. The aims of this study were to identify STAT3-activated cells and to clarify the expression of suppressor of cytokine signal (SOCS), a negative feedback molecule of STAT3, after PH. METHODS: STAT3-activated cells and SOCS1-positive cells were identified by immunohistochemistry after a two-thirds PH in rats. SOCS mRNA was examined by Northern analysis. RESULTS: STAT3 was activated in hepatocytes from those localized in the periportal zones of hepatic lobules after PH. STAT3 activation was also detected in Kupffer cells and sinusoidal endothelial cells prior to its detection in hepatocytes. After STAT3 activation, SOCS1 protein in response to PH was detected immunohistochemically in regenerating liver. SOCS1 and SOCS3 mRNA were induced in regenerating liver after PH. CONCLUSIONS: STAT3 signaling can occur in Kupffer cells and sinusoidal endothelial cells prior to in hepatocytes from those localized in the periportal zones. SOCS1 as well as SOCS3 may regulate STAT3 signaling negatively after PH.
Animals↗
NF-kappaB activation in non-parenchymal liver cells after partial hepatectomy in rats: possible involvement in expression of heparin-binding epidermal growth factor-like growth factor.
BACKGROUND/AIMS: Nuclear factor (NF) B activation plays a critical role in the initiation of liver growth after partial hepatectomy (PH). However, the issue of where specifically NF-B is activated is unclear. We previously reported that heparin-binding epidermal growth factor-like growth factor (HB-EGF) is a hepatotrophic factor. The aims of this study were to identify NF-B-activated cells and to clarify their involvement in HB-EGF expression after PH. METHODS: Using rats, a two-thirds PH was performed, after which NF-B-activated cells and HB-EGF-positive cells were identified by Southwestern histochemistry or immunohistochemistry. NF-B binding activity and HB-EGF gene expression were analyzed in rat hepatocytes and non-parenchymal cells (NPC) in primary culture. RESULTS: NF-B was activated in Kupffer cells and sinusoidal endothelial cells prior to activation in hepatocytes. HB-EGF immunoreactivity was detected after NF-B activation in the sinusoidal cells from those localized in the periportal zones of hepatic lobules. HB-EGF gene expression by tumor necrosis factor was accompanied by an increase in NF-B binding activity in NPC but not in hepatocytes in primary culture, which was abolished by pyrrolidine dithiocarbamate, an inhibitor of NF-B activation. CONCLUSIONS; NF-B was activated in NPC prior to activation in hepatocytes. NF-B activation may be involved in HB-EGF expression in NPC after PH.
Animals↗
Plasma adiponectin levels are not associated with fat oxidation in humans.
OBJECTIVE: To test the hypothesis that low adiponectin is associated with low fat oxidation in humans. RESEARCH METHODS AND PROCEDURES: We measured plasma adiponectin concentrations in 75 healthy, nondiabetic Pima Indians (age, 28 +/- 7 years; 55 men and 20 women; body fat, 29.7 +/- 7.5%) and 18 whites [(age, 33 +/- 8 years; 14 men and 4 women; body fat, 28.2 +/- 10.8% (means +/- SD)] whose body composition was measured by DXA and 24-hour energy expenditure (24-hour EE) by a respiratory chamber. Respiratory quotient (an estimate of whole-body carbohydrate/lipid oxidation rate) was calculated over 24 hours (24-hour RQ). RESULTS: Before correlational analyses, waist-to-thigh ratio (WTR) and percentage of body fat (PFAT) were adjusted for age, sex, and race; 24-hour EE was adjusted for fat mass and fat-free mass, and 24-hour RQ were adjusted for energy balance. Plasma adiponectin concentrations were negatively correlated with WTR (r = -0.42, p < 0.0001) and PFAT (r = -0.46, p < 0.0001). There was no correlation between plasma adiponectin concentrations and 24-hour RQ, (r = 0.09, p = 0.36) before or after adjustment for PFAT (r = 0.001, p = 0.99, respectively, partial correlation), and no correlation was found between plasma adiponectin concentrations and 24-hour EE (r = -0.12, p = 0.27). DISCUSSION: Our cross-sectional data do not suggest physiological concentrations of fasting plasma adiponectin play a role in the regulation of whole-body fat oxidation or energy expenditure in resting conditions. Whether administration of adiponectin to individuals with low levels of this hormone will increase their fat oxidation rates/energy expenditure remains to be established.
Absorptiometry, Photon↗