OBJECTIVETo assess the effects of exenatide on body weight and glucose tolerance in nondiabetic obese subjects with normal or impaired glucose tolerance (IGT) or impaired fasting glucose (IFG).RESEARCH DESIGN AND METHODSObese subjects (n = 152; age 46 ± 12 years, female 82%, weight 108.6 ± 23.0 kg, BMI 39.6 ± 7.0 kg/m2, IGT or IFG 25%) were randomized to receive exenatide (n = 73) or placebo (n = 79), along with lifestyle intervention, for 24 weeks.RESULTSExenatide-treated subjects lost 5.1 ± 0.5 kg from baseline versus 1.6 ± 0.5 kg with placebo (exenatide − placebo, P < 0.001). Placebo-subtracted difference in percent weight reduction was −3.3 ± 0.5% (P < 0.001). Both groups reduced their daily calorie intake (exenatide, −449 cal; placebo, −387 cal). IGT or IFG normalized at end point in 77 and 56% of exenatide and placebo subjects, respectively.CONCLUSIONSExenatide plus lifestyle modification decreased caloric intake and resulted in weight loss in nondiabetic obesity with improved glucose tolerance in subjects with IGT and IFG.

A subset of follicular thyroid carcinomas contains a balanced translocation, t(2;3)(q13;p25), that results in fusion of the paired box gene 8 (PAX8) and peroxisome proliferator-activated receptor c (PPARG) genes with concomitant expression of a PAX8-PPARg fusion protein, PPFP. PPFP is thought to contribute to neoplasia through a mechanism in which it acts as a dominant-negative inhibitor of wild-type PPARg. To better understand this type of follicular carcinoma, we generated global gene expression profiles using DNA microarrays of a cohort of follicular carcinomas along with other common thyroid tumors and used the data to derive a gene expression profile characteristic of PPFP-positive tumors. Transient transfection assays using promoters of four genes whose expression was highly associated with the translocation showed that each can be activated by PPFP. PPFP had unique transcriptional activities when compared with PAX8 or PPARg, although it had the potential to function in ways qualitatively similar to PAX8 or PPARg depending on the promoter and cellular environment. Bioinformatics analyses revealed that genes with increased expression in PPFP-positive follicular carcinomas include known PPAR target genes; genes involved in fatty acid, amino acid, and carbohydrate metabolism; micro-RNA target genes; and genes on chromosome 3p. These results have implications for the neoplastic mechanism of these follicular carcinomas.Well-differentiated thyroid carcinoma, excluding medullary carcinoma, is divided into papillary, follicular, and oncocytic cell types. Papillary carcinoma is the most common form of thyroid cancer. It has several recognized histologic subtypes that share activating mutations of genes within the RET/RAS/ BRAF/MAPK signaling pathway (1, 2), although each papillary carcinoma subtype has a distinct gene expression signature (3). Follicular carcinoma is either associated with mutations of the RAS gene family (4) or a distinctive translocation of chromosomes 2 and 3 that results in fusion of paired box gene 8 (PAX8) with peroxisome proliferator-activated receptor c (PPARG; ref. 5). Unlike the other thyroid carcinomas, the spectrum of mutations present in oncocytic carcinoma remains largely elusive, although mutations of GRIM-19 (NDUFA13), a gene involved in mitochondrial metabolism and regulation of cell death, recently have been identified in a minority of oncocytic carcinomas (6).PAX8 encodes a transcription factor that is expressed at high levels in thyrocytes. It is necessary for normal thyroid development and it directs the expression of many thyroidspecific genes. PPARG encodes a nuclear hormone receptor transcription factor whose activity is related to adipocyte differentiation (7 -9), lipid and carbohydrate metabolism (10), and cellular proliferation and differentiation. PPARg is expressed at very low levels in normal thyroid and has no known function in that organ. In follicular carcinomas with the t(2;3)(q13;p25) translocation, the promoter and 5V coding region of PAX8 are fused in-f...

Follicular thyroid carcinomas are associated with a chromosomal translocation that fuses the thyroid-specific transcription factor paired box gene 8 (PAX8) with the nuclear receptor peroxisome proliferator-activated receptor gamma (PPARgamma). This study investigated the transcriptional mechanisms by which PAX8-PPARgamma regulates follicular thyroid cells. In HeLa cells, rat follicular thyroid (FRTL-5) cells, or immortalized human thyroid cells, PAX8-PPARgamma stimulated transcription from PAX8-responsive thyroperoxidase and sodium-iodide symporter promoters in a manner at least comparable with wild-type PAX8. In contrast, PAX8-PPARgamma failed to stimulate transcription from the thyroglobulin promoter and blocked the synergistic stimulation of this promoter by wild-type PAX8 and thyroid transcription factor-1. Unexpectedly, PAX8-PPARgamma transcriptional function on a PPARgamma-responsive promoter was cell-type dependent; in HeLa cells, PAX8-PPARgamma dominantly inhibited expression of the PPARgamma-responsive promoter, whereas in FRTL-5 and immortalized human thyroid cells PAX8-PPARgamma stimulated this promoter. In gel shift analyses, PAX8-PPARgamma bound a PPARgamma-response element suggesting that its transcriptional function is mediated via direct DNA contact. A biological model of PAX8-PPARgamma function in follicular thyroid cells was generated via constitutive expression of the fusion protein in FRTL-5 cells. In this model, PAX8-PPARgamma expression was associated with enhanced growth as assessed by soft agar assays and thymidine uptake. Therefore, PAX8-PPARgamma disrupts normal transcriptional regulation by stimulating some genes and inhibiting others, the net effect of which may mediate follicular thyroid cell growth and loss of differentiation that ultimately leads to carcinogenesis.

Engagement of the T cell antigen receptor results in both its phosphorylation and its ubiquitination. T cell antigen receptor ubiquitination was evaluated in Jurkat, a well characterized human T leukemia cell line. Treatment of cells with the tyrosine kinase inhibitor herbimycin A resulted in an inhibition of receptor ubiquitination. Consistent with this, pervanadate, which increases cellular tyrosine phosphorylation, enhanced receptor ubiquitination. A requirement for receptormediated tyrosine kinase activity for ubiquitination was confirmed in cells lacking the tyrosine kinase p56 lck and also in cells that are defective in expression of CD45, a tyrosine phosphatase that regulates the activity of p56 lck . The need for tyrosine kinase activation for ubiquitination was not bypassed by directly activating protein kinase C and stimulating endocytosis of receptors. These observations establish ubiquitination of the T cell antigen receptor as a tyrosine kinase-dependent manifestation of transmembrane signaling and suggest a role for tyrosine phosphorylation in the ligand-dependent ubiquitination of mammalian transmembrane receptors.For many transmembrane receptors, including the multisubunit TCR, 1 signaling is initiated by ligand-induced aggregation (1, 2). The earliest obligate intracellular event following TCR aggregation is the activation of the src-family protein tyrosine kinases, Lck (p56 lck ) and Fyn (p59 fyn ). Lck and/or Fyn phosphorylate TCR subunits resulting in the association of a third tyrosine kinase, ZAP-70 (70-kDa -associated protein), with the TCR and to subsequent activation events (3-5). CD45, a tyrosine phosphatase that dephosphorylates key regulatory residues on Lck and Fyn, is also implicated in the initiation of TCR-mediated signaling (6).TCRs consist of six different polypeptides, these include the antigen-recognition element, in most cells an ␣-␤ heterodimer, and a set of invariant signal transducing subunits. The invariant subunits include CD3-␦, -⑀, and -␥ and the structurally distinct TCR-subunit, which exists within the TCR as a disulfide-linked homodimer (4). The minimal signal transducing element of the TCR is the immunoreceptor tyrosine-based activation motif (ITAM) (7). monomers have three ITAMs, and each CD3 subunit has one. ITAMs include two tyrosine residues 10 or 11 amino acids apart that are potential phosphorylation sites. The subunit is a particularly prominent substrate for tyrosine phosphorylation; up to 5% of subunits are phosphorylated on multiple tyrosines upon TCR engagement (8 -11).In addition to being a substrate for tyrosine phosphorylation when cross-linked by antibody or mitogen (11), TCRs also are ubiquitinated. The covalent modification of proteins with chains of ubiquitin, a highly conserved 76-amino acid polypeptide, plays a central role in the targeting of abnormal proteins and a number of regulatory cytosolic and nuclear proteins for degradation in the 26 S proteasome (12-16). Ubiquitination occurs via a multienzyme process involving families of enzymes ter...

Background Clinical complexity is increasingly prevalent among patients with atrial fibrillation (AF). The ‘Atrial fibrillation Better Care’ (ABC) pathway approach has been proposed to streamline a more holistic and integrated approach to AF care; however, there are limited data on its usefulness among clinically complex patients. We aim to determine the impact of ABC pathway in a contemporary cohort of clinically complex AF patients. Methods From the ESC-EHRA EORP-AF General Long-Term Registry, we analysed clinically complex AF patients, defined as the presence of frailty, multimorbidity and/or polypharmacy. A K-medoids cluster analysis was performed to identify different groups of clinical complexity. The impact of an ABC-adherent approach on major outcomes was analysed through Cox-regression analyses and delay of event (DoE) analyses. Results Among 9966 AF patients included, 8289 (83.1%) were clinically complex. Adherence to the ABC pathway in the clinically complex group reduced the risk of all-cause death (adjusted HR [aHR]: 0.72, 95%CI 0.58–0.91), major adverse cardiovascular events (MACEs; aHR: 0.68, 95%CI 0.52–0.87) and composite outcome (aHR: 0.70, 95%CI: 0.58–0.85). Adherence to the ABC pathway was associated with a significant reduction in the risk of death (aHR: 0.74, 95%CI 0.56–0.98) and composite outcome (aHR: 0.76, 95%CI 0.60–0.96) also in the high-complexity cluster; similar trends were observed for MACEs. In DoE analyses, an ABC-adherent approach resulted in significant gains in event-free survival for all the outcomes investigated in clinically complex patients. Based on absolute risk reduction at 1 year of follow-up, the number needed to treat for ABC pathway adherence was 24 for all-cause death, 31 for MACEs and 20 for the composite outcome. Conclusions An ABC-adherent approach reduces the risk of major outcomes in clinically complex AF patients. Ensuring adherence to the ABC pathway is essential to improve clinical outcomes among clinically complex AF patients.