Proteomic mapping of bezafibrate-treated human hepatocytes in primary culture using two-dimensional liquid chromatography

In vitro cytogenetic toxicity of bezafibrate in human peripheral blood lymphocytes

Bezafibrate (BF) is a peroxisome proliferator-activated receptor (PPAR) agonist used as a lipid-lowering agent to treat both the familial or acquired combined forms of hyperlipidemia. BF is the only available fibrate drug that acts on all PPAR subtypes of α, β, and δ. Although there are studies that indicate a genotoxic potential associated with the use of fibrates, to our knowledge, the genotoxicity of BF in human peripheral blood lymphocytes has not been studied. In the present study, the genotoxic potential of BF was evaluated using chromosome aberration (CA) and micronucleus (MN) assays in peripheral blood lymphocytes of healthy human subjects. In addition, a high performance liquid chromatography (HPLC) method was used to identify and quantitate the drug passage into the cells. Human peripheral blood lymphocytes were exposed to four different concentrations (100, 175, 250 and 325 μg/mL) of BF for 24- and 48-h treatment periods. As shown by HPLC, in spite of significant passage of BF into human peripheral blood lymphocytes in 24- and 48-h treatment periods, BF was not found to increase the CA and MN frequency. On the other hand, exposing cells to BF for 24- and 48-h treatment periods caused significant concentration-dependent decreases in the mitotic index (r = -0.995, p < 0.01 for 24-h; r = -0.992, p < 0.01 for 48-h) and nuclear division index (r = -0.990, p < 0.01 for 24-h; r = -0.981, p < 0.01 for 48-h). Our results suggest that BF has cytotoxic effect on cultured human peripheral blood lymphocytes.

Interactive protein network of FXIII-A1 in lipid rafts of activated and non-activated platelets

Lipid-rafts are defined as membrane microdomains enriched in cholesterol and glycosphingolipids within platelet plasma membrane. Lipid raft-mediated clot retraction requires factor XIII and other interacting proteins. The aim of this study was to investigate the proteins that interact with factor XIII in raft and non-raft domains of activated and non-activated platelet plasma membrane. By lipidomics analysis, we identified cholesterol- and sphingomyelin-enriched areas as lipid rafts. Platelets were activated by thrombin. Proteomics analysis provided an overview of the pathways in which proteins of rafts and non-rafts participated in the interaction network of FXIII-A1, a catalytic subunit of FXIII. "Platelet activation" was the principal pathway among KEGG pathways for proteins of rafts, both before and after activation. Network analysis showed four types of interactions (activation, binding, reaction, and catalysis) in raft and non-raft domains in interactive network of FXIII-A1. FXIII-A1 interactions with other proteins in raft domains and their role in homeostasis highlight the specialization of the raft domain in clot retraction via the Factor XIII protein network.

Proteomics for systems toxicology

Current toxicology studies frequently lack measurements at molecular resolution to enable a more mechanism-based and predictive toxicological assessment. Recently, a systems toxicology assessment framework has been proposed, which combines conventional toxicological assessment strategies with system-wide measurement methods and computational analysis approaches from the field of systems biology. Proteomic measurements are an integral component of this integrative strategy because protein alterations closely mirror biological effects, such as biological stress responses or global tissue alterations. Here, we provide an overview of the technical foundations and highlight select applications of proteomics for systems toxicology studies. With a focus on mass spectrometry-based proteomics, we summarize the experimental methods for quantitative proteomics and describe the computational approaches used to derive biological/mechanistic insights from these datasets. To illustrate how proteomics has been successfully employed to address mechanistic questions in toxicology, we summarized several case studies. Overall, we provide the technical and conceptual foundation for the integration of proteomic measurements in a more comprehensive systems toxicology assessment framework. We conclude that, owing to the critical importance of protein-level measurements and recent technological advances, proteomics will be an integral part of integrative systems toxicology approaches in the future.