The recently described variant of the human beta3-adrenergic receptor (AR) gene located mainly in visceral adipocytes is associated with earlier onset of NIDDM, abdominal obesity, insulin resistance, and an increased capacity to gain weight. We investigated whether lipolysis in human omental adipocytes induced by a potent and selective human beta3-AR agonist (L-755,507) was affected by the Trp64Arg mutation of the beta3-adrenoceptor, using 18 omental fat samples obtained during total hysterectomy. The Trp64Arg mutation was determined by polymerase chain reaction-restriction fragment length polymorphism analysis. Arg64 homozygous (n = 4) had a lower median effective concentration (EC50) and lower responsiveness compared with wild-type (n = 8) (EC50: -6.55 +/- 0.21 vs. -7.53 +/- 0.35 log mol/l, P = 0.007; responsiveness: 3.48 +/- 0.32 vs. 5.76 +/- 0.36 micromol x 10(5) cells(-1) x 90 min(-1), P = 0.014, respectively), although there was no difference in lipolysis induced by isoproterenol or CGP12177. Trp64Arg heterozygous (n = 6) also had a significantly lower EC50 and lower responsiveness (EC50: -6.18 +/- 0.09 log mol/l; responsiveness: 4.17 +/- 0.33 micromol x 10(5) cells(-1) x 90 min(-1)). We concluded that the Trp64Arg mutation of the beta3-AR gene is associated with lower lipolytic activities.

Using a chimeric mouse humanized liver model, we provided evidence that human hepatocytes are refractory to the mitogenic effects of rodent constitutive androstane receptor (CAR) activators. To evaluate the functional reliability of this model, the present study examined mitogenic responses to phenobarbital (PB) in chimeric mice transplanted with rat hepatocytes, since rats are responsive to CAR activators. Treatment with 1000 ppm PB for 7 days significantly increased replicative DNA synthesis (RDS) in rat hepatocytes of the chimeric mice, demonstrating that the transplanted hepatocyte model is functionally reliable for cell proliferation analysis. Treatment of humanized CAR and pregnane X receptor (PXR) mice (hCAR/hPXR mice) with 1000 ppm PB for 7 days significantly increased hepatocyte RDS together with increases in several mitogenic genes. Global gene expression analysis was performed with liver samples from this and from previous studies focusing on PB-induced Wnt/β-catenin signaling, and showed that altered genes in hCAR/hPXR mice clustered most closely with liver tumor samples from a diethylnitrosamine/PB initiation/promotion study than with wild type mice. However, different gene clusters were observed for chimeric mice with human hepatocytes for Wnt/β-catenin signaling when compared to those of hCAR/hPXR mice, wild type mice and liver tumor samples. The results of this study demonstrate clear differences in the effects of PB on hepatocyte RDS and global gene expression between human hepatocytes of chimeric mice and hCAR/hPXR mice, suggesting that the chimeric mouse model is relevant to humans for studies on the hepatic effects of rodent CAR activators, whereas the hCAR/hPXR mouse is not.

inhibitor GPD-1116 markedly attenuates the development of cigarette smoke-induced emphysema in senescence-accelerated mice P1 strain. Am J Physiol Lung Cell Mol Physiol 294: L196-L204, 2008. First published November 9, 2007 doi:10.1152/ajplung.00173.2007.-Phosphodiesterase 4 (PDE4) is an intracellular enzyme specifically degrading cAMP, a second messenger exerting inhibitory effects on many inflammatory cells. To investigate whether GPD-1116 (a PDE4 inhibitor) prevents murine lungs from developing cigarette smoke-induced emphysema, the senescence-accelerated mouse (SAM) P1 strain was exposed to either fresh air or cigarette smoke for 8 wk with or without oral administration of GPD-1116. We confirmed the development of smoke-induced emphysema in SAMP1 [air vs. smoke (means Ϯ SE); the mean linear intercepts (MLI), 52.9 Ϯ 0.8 vs. 68.4 Ϯ 4.2 m, P Ͻ 0.05, and destructive index (DI), 4.5% Ϯ 1.3% vs. 16.0% Ϯ 0.4%, P Ͻ 0.01]. Emphysema was markedly attenuated by GPD-1116 (MLI ϭ 57.0 Ϯ 1.4 m, P Ͻ 0.05; DI ϭ 8.2% Ϯ 0.6%, P Ͻ 0.01) compared with smoke-exposed SAMP1 without GPD-1116. Smokeinduced apoptosis of lung cells were also reduced by administration of GPD-1116. Matrix metalloproteinase (MMP)-12 activity in bronchoalveolar lavage fluid (BALF) was increased by smoke exposure (air vs. smoke, 4.1 Ϯ 1.1 vs. 40.5 Ϯ 16.2 area/g protein; P Ͻ 0.05), but GPD-1116 significantly decreased MMP-12 activity in smokeexposed mice (5.3 Ϯ 2.1 area/g protein). However, VEGF content in lung tissues and BALF decreased after smoke exposure, and the decrease was not markedly restored by oral administration of GPD-1116. Our study suggests that GPD-1116 attenuates smoke-induced emphysema by inhibiting the increase of smoke-induced MMP-12 activity and protecting lung cells from apoptosis, but is not likely to alleviate cigarette smoke-induced decrease of VEGF in SAMP1 lungs.protease; aging; apoptosis; oxidative stress; vascular endothelial growth factor CHRONIC OBSTRUCTIVE PULMONARY disease (COPD) is a disease state characterized by airflow limitation and is a global health problem in terms of morbidity, mortality, and economic burden (16). Chronic cigarette smoke exposure is the most important risk factor and induces chronic inflammation of the airways and lung parenchyma by recruiting and activating inflammatory cells to release proteinases, particularity elastase from neutrophils and various metalloproteinases from alveolar macrophages. Accordingly, drugs that control the underlying inflammatory and destructive processes are required for the treatment of COPD.Phosphodiesterases (PDEs) are intracellular enzymes that degrade cyclic nucleotides. Among many isozymes, phosphodiesterase 4 (PDE4) specifically degrades cAMP, a second messenger exerting inhibitory effects on many inflammatory cells. PDE4 is ubiquitously expressed among inflammatory and immune cells including neutrophils, CD8ϩ T cells, macrophages, mast cells, eosinophils, and airway epithelial cells (1,17,30). PDE4 inhibitors show suppressive effects on various in vitro responses, ...

Phenobarbital (PB) is a nongenotoxic hepatocellular carcinogen in rodents. PB induces hepatocellular tumors by activating the constitutive androstane receptor (CAR). Some previous research has suggested the possible involvement of epigenetic regulation in PB-promoted hepatocellular tumorigenesis, but the details of its molecular mechanism are not fully understood. In the present study, comprehensive analyses of DNA methylation, hydroxymethylation and gene expression using microarrays were performed in mouse hepatocellular adenomas induced by a single 90 mg kg intraperitoneal injection dose of diethylnitrosamine (DEN) followed by 500 ppm PB in the diet for 27 weeks. DNA modification and expression of hundreds of genes are coordinately altered in PB-induced mouse hepatocellular adenomas. Of these, gene network analysis showed alterations of CAR signaling and tumor development-related genes. Pathway enrichment analysis revealed that differentially methylated or hydroxymethylated genes belong mainly to pathways involved in development, immune response and cancer cells in contrast to differentially expressed genes belonging primarily to the cell cycle. Furthermore, overlap was evaluated between the genes with altered expression levels with 5-methylcytosine (5mC) and 5-hydroxymethylcytosine (5hmC) alterations in mouse hepatocellular adenoma induced by DEN/PB and the genes with altered expression levels in the liver of CD-1 mice or humanized chimeric mice treated with PB for 7 days. With the integration of transcriptomic and epigenetic approaches, we detected candidate genes responsible for early key events of PB-promoted mouse hepatocellular tumorigenesis. Interestingly, these genes did not overlap with genes altered by the PB treatment of humanized chimeric mice, thus suggesting a species difference between the effects of PB in mouse and human hepatocytes.

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