No abstract

No abstract

The mitochondrial uncoupling protein of brown adipose tissue (UCP1) was expressed in skeletal muscle and heart of transgenic mice at levels comparable with the amount found in brown adipose tissue mitochondria. These transgenic mice have a lower body weight, and when related to body weight, food intake and energy expenditure are increased. A specific reduction of muscle mass was observed but varied according to the contractile activity of muscles. Heart and soleus muscle are unaffected, indicating that muscles undergoing regular contractions, and therefore with a continuous mitochondrial ATP production, are protected. In contrast, the gastrocnemius and plantaris muscles showed a severely reduced mass and a fast to slow shift in fiber types promoting mainly IIa and IIx fibers at the expense of fastest and glycolytic type IIb fibers. These observations are interpreted as a consequence of the strong potential dependence of the UCP1 protonophoric activity, which ensures a negligible proton leak at the membrane potential observed when mitochondrial ATP production is intense. Therefore UCP1 is not deleterious for an intense mitochondrial ATP production and this explains the tolerance of the heart to a high expression level of UCP1. In muscles at rest, where ATP production is low, the rise in membrane potential enhances UCP1 activity. The proton return through UCP1 mimics the effect of a sustained ATP production, permanently lowering mitochondrial membrane potential. This very likely constitutes the origin of the signal leading to the transition in fiber types at rest. Uncoupling protein 1 (UCP1)1 is expressed exclusively in brown adipose tissue (reviewed in Refs. 1 and 2). Its presence in brown fat mitochondria is responsible for heat production by the mitochondria in brown adipocytes. UCP1 allows return of protons into the matrix without ATP synthesis, and therefore dissipates the proton electrochemical gradient built up after proton pumping by the respiratory complexes. When this gradient reaches high values this makes proton pumping and thus substrate oxidation less easy and therefore slows down respiration. Activity of UCP1 prevents this rise of the proton gradient and therefore allows respiration to occur at a high rate, without phosphorylation of ADP into ATP, and therefore energy is instantaneously released as heat. The essential role of the UCP1 in thermogenesis is illustrated by the cold intolerance of mice whose ucp1 gene has been disrupted (3). Recently, two genes coding for proteins highly homologous to UCP1 have been described (reviewed in Refs. 4 -6). Although there are experimental evidence supporting the hypothesis of an uncoupling activity of these proteins (7,8), their physiological relevance is still incompletely resolved (9 -11). We intended to obtain transgenic mice overexpressing the UCP1 in skeletal muscles, with the aim of examining the effects of the presence of this uncoupling protein on the pattern of myosin expression and metabolic characteristics of locomotor muscles. Two other reports pub...

c-Yes, a member of the Src tyrosine kinase family, is found highly activated in colon carcinoma but its importance relative to c-Src has remained unclear. Here we show that, in HT29 colon carcinoma cells, silencing of c-Yes, but not of c-Src, selectively leads to an increase of cell clustering associated with a localisation of β-catenin at cell membranes and a reduction of expression of β-catenin target genes. c-Yes silencing induced an increase in apoptosis, inhibition of growth in soft-agar and in mouse xenografts, inhibition of cell migration and loss of the capacity to generate liver metastases in mice. Re-introduction of c-Yes, but not c -Src, restores transforming properties of c-Yes depleted cells. Moreover, we found that c-Yes kinase activity is required for its role in β-catenin localisation and growth in soft agar, whereas kinase activity is dispensable for its role in cell migration. We conclude that c-Yes regulates specific oncogenic signalling pathways important for colon cancer progression that is not shared with c-Src.

Venous insufficiency is a multifactorial pathology that has an important impact on the quality of life of the patients. The primary factor of venous disease is an abnormal wall distensibility, which seems to be correlated with genetic factors. Facilitating factors include hormonal impregnation and prolonged hydrostatic load, particularly under conditions where the control of the sympathetic nervous system is reduced by an increase in local temperature. The resulting valvular incompetence, combined with the augmented hydrostatic load, leads to varicosis and venous stasis. The ensuing tissue hypoxia and local edema favor inflammation and infection, which ultimately favor the occurrence of ulcers. The available data on the impact of the disease suggest a relation between the physiopathological phenomena and some parameters of health-related quality of life.

PurposeUveal melanoma (UM) is associated with a high risk of metastases and lack of efficient therapies. Reduced capacity for apoptosis induction by chemotherapies is one obstacle to efficient treatments. Human UM is characterized by high expression of the anti-apoptotic protein Bcl-2. Consequently, regulators of apoptosis such as Bcl-2 family inhibitors may constitute an attractive approach to UM therapeutics. In this aim, we have investigated the efficacy of the Bcl-2/Bcl-XL inhibitor S44563 on 4 UM Patient-Derived Xenografts (PDXs) and derived-cell lines.Experimental DesignFour well characterized UM PDXs were used for in vivo experiments. S44563 was administered alone or combined with fotemustine either concomitantly or after the alkylating agent. Bcl-2, Bcl-XL, and Mcl-1 expressions after S44563 administration were evaluated by immunohistochemistry (IHC).ResultsS44563 administered alone by at 50 and 100 mg/kg i.p. induced a significant tumour growth inhibition in only one xenograft model with a clear dose effect. However, when S44563 was concomitantly administered with fotemustine, we observed a synergistic activity in 3 out of the 4 tested models. In addition, S44563 administered after fotemustine induced a tumour growth delay in 2 out of 3 tested xenografts. Finally, IHC analyses showed that Bcl-2, Bcl-XL, and Mcl-1 expression were not modified after S44563 administration.ConclusionThe novel anti-apoptotic experimental compound S44563, despite a relative low efficacy when administered alone, increased the efficacy of fotemustine in either concomitant or sequential combinations or indeed subsequent to fotemustine. These data support further exploration of potential therapeutic effect of Bcl-2/Bcl-xl inhibition in human UM.

INTRODUCTION:The purpose of this study was to test the continuing validity of the hypothesis that neuropeptide Y (NPY) produced in the brain controls food intake through an interaction with the NPY Y 5 receptor subtype.METHODS: The hypothesis was tested using CGP 71683A a potent and highly selective non-peptide antagonist of the NPY Y 5 receptor which was administered into the right lateral ventricle of obese Zucker faafa rats. RESULTS: Intraventricular injection of 3.4 nmolakg NPY increased food intake during a 2 h test period. Doses of CGP 71683A in excess of 15 nmolakg (i.cv.) resulted in blockade of the increase in food intake produced by NPY. Repeated daily injection of CGP 71683A (30 ± 300 nmolakg, i.cv.) immediately before the dark phase produced a dose-dependent and slowly developing decrease in food intake. CGP 71683A has a low af®nity for NPY Y 1 , Y 2 and Y 4 receptors but a very high af®nity for the NPY Y 5 receptor (Ki, 1.4 nM). Surprisingly, CGP 71683A had similarly high af®nity for muscarinic receptors (Ki, 2.7 nM) and for the serotonin uptake recognition site (Ki, 6.2 nM) in rat brain. Anatomic analysis of the brain after treatment with CGP 71683A demonstrated an in¯ammatory response associated with the fall in food intake. CONCLUSIONS: While the fall in food intake in response to CGP 71683A may have a Y 5 component, interactions with other receptors or in¯ammatory mediators may also play a role. It is concluded that CGP 71683A is an imprecise tool for investigating the role of the NPY Y 5 receptor in the control of physiological processes including food intake. International Journal of Obesity (2001) 25, 84 ± 94

Rosiglitazone (RSG), developed for the treatment of type 2 diabetes mellitus, is known to have potent effects on carbohydrate and lipid metabolism leading to the improvement of insulin sensitivity in target tissues. To further assess the capacity of RSG to normalize gene expression in insulin-sensitive tissues, we compared groups of 18-day-treated db/db mice with increasing oral doses of RSG (10, 30, and 100 mg/kg/d) with untreated non-diabetic littermates (db/+). For this aim, transcriptional changes were measured in liver, inguinal adipose tissue (IAT) and soleus muscle using microarrays and real-time PCR. In parallel, targeted metabolomic assessment of lipids (triglycerides (TGs) and free fatty acids (FFAs)) in plasma and tissues was performed by UPLC-MS methods. Multivariate analyses revealed a relationship between the differential gene expressions in liver and liver trioleate content and between blood glucose levels and a combination of differentially expressed genes measured in liver, IAT, and muscle. In summary, we have integrated gene expression and targeted metabolomic data to present a comprehensive overview of RSG-induced changes in a diabetes mouse model and improved the molecular understanding of how RSG ameliorates diabetes through its effect on the major insulin-sensitive tissues.