Sequence-specific DNA-binding activators, key regulators of gene expression, stimulate transcription in part by targeting the core promoter recognition TFIID complex and aiding in its recruitment to promoter DNA. Although it has been established that activators can interact with multiple components of TFIID, it is unknown whether common or distinct surfaces within TFIID are targeted by activators and what changes if any in the structure of TFIID may occur upon binding activators. As a first step toward structurally dissecting activator/TFIID interactions, we determined the three-dimensional structures of TFIID bound to three distinct activators (i.e., the tumor suppressor p53 protein, glutamine-rich Sp1 and the oncoprotein c-Jun) and compared their structures as determined by electron microscopy and single-particle reconstruction. By a combination of EM and biochemical mapping analysis, our results uncover distinct contact regions within TFIID bound by each activator. Unlike the coactivator CRSP/Mediator complex that undergoes drastic and global structural changes upon activator binding, instead, a rather confined set of local conserved structural changes were observed when each activator binds holo-TFIID. These results suggest that activator contact may induce unique structural features of TFIID, thus providing nanoscale information on activator-dependent TFIID assembly and transcription initiation.[Keywords: TAF; TFIID; transcription; activator; structure] Supplemental material is available at http://www.genesdev.org.

Transarterial chemoembolization (TACE) is one of the standard therapies for bridging patients with hepatocellular carcinoma (HCC) to transplantation. This study aimed to determine which features on pre- and post-TACE imaging are associated with tumor necrosis on pathologic specimens. Records of 105 patients with 132 HCC lesions who underwent liver transplantation following TACE were retrospectively reviewed. Greater than 90% necrosis was achieved in 70% of nodules. Development of greater than 90% lesion necrosis at pathology was associated with avid lesion enhancement (p=0.03) and presence of a feeding vessel larger than 0.9 mm in diameter on the pre-TACE visceral angiogram (p=0.008). Near-complete lesion necrosis was also associated with extensive ethiodized oil accumulation within a lesion during TACE administration (p=0.02). On post-TACE computed tomography, lack of residual contrast enhancement (p<0.0001), decrease in lesion size (p=0.009), high lesion density due to ethiodized oil accumulation (p=0.005), and diffuse distribution of ethiodized oil throughout the lesion (p<0.0001) were also correlated with near-complete lesion necrosis at pathology. In conclusion, this study found multiple pre-TACE and post-TACE imaging characteristics of HCC which were associated with near complete tumor necrosis at histopathology following TACE. These findings may help guide selection of an optimal treatment strategy for bridging patients with HCC to liver transplant.

In the current study, we used muscle-specific TRIB3 overexpressing (MOE) and knockout (MKO) mice to determine whether TRIB3 mediates glucose-induced insulin resistance in diabetes and whether alterations in TRIB3 expression as a function of nutrient availability have a regulatory role in metabolism. In streptozotocin diabetic mice, TRIB3 MOE exacerbated, whereas MKO prevented, glucose-induced insulin resistance and impaired glucose oxidation and defects in insulin signal transduction compared with wild-type (WT) mice, indicating that glucose-induced insulin resistance was dependent on TRIB3. In response to a high-fat diet, TRIB3 MOE mice exhibited greater weight gain and worse insulin resistance in vivo compared with WT mice, coupled with decreased AKT phosphorylation, increased inflammation and oxidative stress, and upregulation of lipid metabolic genes coupled with downregulation of glucose metabolic genes in skeletal muscle. These effects were prevented in the TRIB3 MKO mice relative to WT mice. In conclusion, TRIB3 has a pathophysiological role in diabetes and a physiological role in metabolism. Glucose-induced insulin resistance and insulin resistance due to diet-induced obesity both depend on muscle TRIB3. Under physiological conditions, muscle TRIB3 also influences energy expenditure and substrate metabolism, indicating that the decrease and increase in muscle TRIB3 under fasting and nutrient excess, respectively, are critical for metabolic homeostasis.

Our results show that relative levels of circulating miR-16, -107, -33, -150, and -222 are associated with insulin sensitivity and metabolic risk factors, and suggest that multiple miRs may act in concert to produce insulin resistance and the clustering of associated traits that comprise the MetS. Therefore, miRs may have potential as novel therapeutic targets or agents in cardiometabolic disease.

Context:F2-isoprostanes (F2-isoPs) are biomarkers for oxidative stress in humans and have been shown to be elevated in obesity, cardiovascular disease, and diabetes. Therefore, F2-isoPs are often implicated in oxidative stress contributing to insulin resistance, although this has not been rigorously examined.Objective:To determine whether urinary F2-isoPs are predictive of insulin sensitivity and other clinical metabolic parameters.Participants:Sedentary, weight-stable, nondiabetic adults equilibrated on a standard isocaloric diet.Main Outcome Measures:Insulin sensitivity via hyperinsulinemic-euglycemic clamp, urinary F2-isoPs by gas chromatography-mass spectrometry, and body composition by dual-energy x-ray absorptiometry.Results:No correlation was found between 15-F2t-IsoP nor its major metabolite, 2,3-dinor-5,6-dihydro-15-F2t-IsoP, with insulin sensitivity, even after adjusting for age, race, sex, BMI, and smoking status. 15-F2t-IsoP was also not associated with body fat. However, there was a strong negative correlation between 15-F2t-IsoP and lean body mass (LBM; r = −0.46, P = 0.0001), bone mineral content (BMC; r = −0.58, P < 0.0001), bone mineral density (BMD; r = −0.65, P < 0.0001), and skeletal muscle protein 4-hydroxynonenal (4-HNE; r = −0.54, P = 0.0239), another marker of oxidative stress. 15-F2t-IsoP was also positively associated with circulating triglycerides and total cholesterol, and increased as a function of age.Conclusions:Urinary 15-F2t-IsoP and its major metabolite are not associated with insulin sensitivity, suggesting the lipid peroxidation process that produces F2-isoPs does not reflect oxidative stress reactions operative in insulin resistance. However, urinary F2-isoPs were negatively correlated with LBM, BMC, BMD, and muscle 4-HNE. Because lean and bone mass decline as a function of biological aging, F2-isoPs may reflect the oxidative stress operative in the aging process.

Background: Insulin resistance is central in the pathophysiology of cardiometabolic disease; however, common mechanisms that explain the parallel development of both type 2 diabetes and atherosclerosis have not been elucidated. We have previously shown that tribbles homolog 3 (TRB3) can exert a chronic pathophysiological role in promoting insulin resistance and also has an acute physiological role to alternatively regulate glucose uptake in fat and muscle during short-term fasting and nutrient excess. Since TRB3 is expressed in human atherosclerotic plaques, we explored its role in foam cell formation to assess its potential contribution to atherogenesis. Methods: We have used human THP-1 monocytes, which transition to lipid-laden macrophage foam cells when exposed to oxidized low-density lipoprotein (ox-LDL). Results: We first observed that TRB3 was upregulated by more than twofold (P < 0.01) within 24 hr of treatment with ox-LDL. To determine whether TRB3 actively participated in foam cell formation, we overexpressed TRB3 in THP-1 monocytes and found that this led to a 1.5-fold increase in cholesterol accumulation after 48 hr (P < 0.01), compared with controls. At the same time, TRB3 overexpression suppressed inflammation in macrophages as evidenced by reduced expression and secretion of tumor necrosis factor alpha (TNF-a) and interleukin-1 beta (IL-1b) (both P < 0.01). Conclusions: (1) TRB3 is upregulated in macrophages upon treatment with ox-LDL; (2) TRB3 promotes lipid accumulation and suppresses cytokine expression; and (3) inflammation and foam cell formation can be reciprocally regulated, and TRB3 orients the macrophage to assume a more primary role for lipid accumulation while maintaining a secondary role as an inflammatory immune cell.

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