Investigation of the Acetylation Mechanism by GCN5 Histone Acetyltransferase

The histone acetylation of post-translational modification can be highly dynamic and play a crucial role in regulating cellular proliferation, survival, differentiation and motility. Of the enzymes that mediate post-translation modifications, the GCN5 of the histone acetyltransferase (HAT) proteins family that add acetyl groups to target lysine residues within histones, has been most extensively studied. According to the mechanism studies of GCN5 related proteins, two key processes, deprotonation and acetylation, must be involved. However, as a fundamental issue, the structure of hGCN5/AcCoA/pH3 remains elusive. Although biological experiments have proved that GCN5 mediates the acetylation process through the sequential mechanism pathway, a dynamic view of the catalytic process and the molecular basis for hGCN5/AcCoA/pH3 are still not available and none of theoretical studies has been reported to other related enzymes in HAT family. To explore the molecular basis for the catalytic mechanism, computational approaches including molecular modeling, molecular dynamic (MD) simulation and quantum mechanics/molecular mechanics (QM/MM) simulation were carried out. The initial hGCN5/AcCoA/pH3 complex structure was modeled and a reasonable snapshot was extracted from the trajectory of a 20 ns MD simulation, with considering post-MD analysis and reported experimental results. Those residues playing crucial roles in binding affinity and acetylation reaction were comprehensively investigated. It demonstrated Glu80 acted as the general base for deprotonation of Lys171 from H3. Furthermore, the two-dimensional QM/MM potential energy surface was employed to study the sequential pathway acetylation mechanism. Energy barriers of addition-elimination reaction in acetylation obtained from QM/MM calculation indicated the point of the intermediate ternary complex. Our study may provide insights into the detailed mechanism for acetylation reaction of GCN5, and has important implications for the discovery of regulators against GCN5 enzymes and related HAT family enzymes

Imaging findings in noncraniofacial childhood rhabdomyosarcoma

Rhabdomyosarcoma (RMS) is the most common soft-tissue sarcoma of childhood. This paper is focuses on imaging for diagnosis, staging, and follow-up of noncraniofacial RMS

With or Without You - Do Financial Data Help to Forecast Industrial Production?

This paper analyzes the forecasting performance of financial market data in comparison to other indicator groups to forecast industrial production for Germany and the US. We focus on single-indicator models and various weighting schemes and evaluate the forecasting performance using a significance test. In addition, we investigate the stability of forecasting models before and during the recent financial crisis. This paper shows that financial market indicators are useful for short-term forecasting, especially for the US and longer forecast horizons. Nevertheless, the results indicate that the Great Recession was not foreseeable even if financial market indicators were taking into account. Furthermore, the reliability of pooled forecasts is higher than most of the forecasts obtained from single-indicator models.In diesem Papier wird die Fähigkeit von Finanzmarktindikatoren im Vergleich zu anderen Kategorien von Indikatoren für die Prognose der Industrieproduktion in Deutschland und der USA verglichen. Dafür werden einzelne Gleichungen, in die die Indikatoren einfließen, und verschiedene Gewichtungsschemen herangezogen, um die Prognoseleistung zu evaluieren. Darüber hinaus wird die Stabilität der Prognosegüte untersucht, indem sie vor und während der Finanzmarktkrise verglichen wird. Es zeigt sich, dass Finanzmarktindikatoren durchaus nützlich für Kurzfristprognosen sind, insbesondere für die USA und wenn der Prognosezeitraum mehrere Monate umfasst. Nichtsdestotrotz lässt sich festhalten, dass auch unter Berücksichtigung von Finanzmarktindikatoren die Große Rezession nicht hätte vorhergesehen werden können. Zudem zeigt sich, dass Prognosen, die auf Gewichtungsschemen beruhen, stabiler sind als die von einzelnen Indikatorenmodellen

Synthetic high-density lipoprotein nanodisks for targeted withalongolide delivery to adrenocortical carcinoma

Rui Kuai,1,2,* Chitra Subramanian,3,* Peter T White,3,* Barbara N Timmermann,4 James J Moon,1,2,5 Mark S Cohen,3,6 Anna Schwendeman1,2 1Department of Pharmaceutical Sciences, College of Pharmacy, 2Biointerfaces Institute, University of Michigan, 3Department of Surgery, University of Michigan, Ann Arbor, MI, 4Department of Medicinal Chemistry, University of Kansas, Lawrence, KS, 5Department of Biomedical Engineering, 6Department of Pharmacology, University of Michigan, Ann Arbor, MI, USA *These authors contributed equally to this work Abstract: Adrenocortical carcinoma (ACC) is a rare endocrine malignancy and has a 5-year survival rate of <35%. ACC cells require cholesterol for steroid hormone production, and this requirement is met via expression on the cell surface of a high level of SRB1, responsible for the uptake of high-density lipoproteins (HDLs), which carry and transport cholesterol in vivo. Here, we describe how this natural lipid carrier function of SRB1 can be utilized to improve the tumor-targeted delivery of a novel natural product derivative – withalongolide A 4,19,27-triacetate (WGA-TA) – which has shown potent antitumor efficacy, but poor aqueous solubility. Our strategy was to use synthetic HDL (sHDL) nanodisks, which are effective in tumor-targeted delivery due to their smallness, long circulation half-life, documented safety, and ability to bind to SRB1. In this study, we prepared sHDL nanodisks using an optimized phospholipid composition combined with ApoA1 mimetic peptide (22A), which has previously been tested in clinical trials, to load WGA-TA. Following optimization, WGA-TA nanodisks showed drug encapsulation efficiency of 78%, a narrow particle size distribution (9.81±0.41 nm), discoid shape, and sustained drug release in phosphate buffered saline. WGA-TA-sHDL nanodisks exhibited higher cytotoxicity in the ACC cell line H295R half maximal inhibitory concentration ([IC50] 0.26±0.045 µM) than free WGA-TA (IC50 0.492±0.115 µM, P<0.05). Fluorescent dye-loaded sHDL nanodisks efficiently accumulated in H295R adrenal carcinoma xenografts 24 hours following dosing. Moreover, daily intraperitoneal administration of 7 mg/kg WGA-TA-loaded sHDL nanodisks significantly inhibited tumor growth during 21-day administration to H295R xenograft-bearing mice compared to placebo (P<0.01). Collectively, these results suggest that WGA-TA-loaded nanodisks may represent a novel and beneficial therapeutic strategy for the treatment of ACC. Keywords: synthetic high-density lipoproteins, scavenger receptor class B1, targeted delivery, nanodisks, withalongolides, adrenocortical carcinoma