Effects of chemical exposure on rat serum proteins revealed by a modified technique of two-dimensional gel electrophoresis

Monitoring the effects of drug treatment in rat models of disease by serum protein analysis

In this review we list from literature investigations on rat serum proteins using electrophoretic techniques in connection with drug testing. From our own research work, we provide annotated two-dimensional maps of rat serum proteins under control and experimental conditions. Emphasis is on species-specific components and on the effects of acute and chronic inflammation. We discuss our project of structural proteomics on rat serum as a minimally invasive approach to pharmacological investigation, and we outline a typical experimental plan for drug testing according to the above guidelines. We then report in detail on the results of our trials of anti-inflammatory drugs on adjuvant arthritis, an animal model of disease resembling in many aspects human rheumatoid arthritis. We demonstrate a correlation between biochemical parameters and therapeutic findings and outline the advantages of the chosen methodological approach, which proved also sensitive in revealing "side effects" of the test drugs. In an appendix we describe our experimental protocol when performing two-dimensional electrophoresis of rat serum.

Proteins of rat serum IV. Time-course of acute-phase protein expression and its modulation by indomethacine

Changes in the concentration of major serum proteins were monitored from day 0 to day 4 in three experimental groups: rats injected with turpentine, rats receiving the turpentine shot and daily doses of indomethacine, and rats given indomethacine alone. In inflamed animals, peak changes for acute-phase reactants, evaluated by two-dimensional electrophoresis (2-DE), were usually observed between 48 and 72 h after the phlogistic stimulus. By itself, indomethacine was found to affect the synthesis of most proteins (except one of the thiostatin variants and ceruloplasmin); the changes in serum levels, whether positive or negative, were the same as upon inflammation (except for kallikrein-binding protein), but their extent and/or timing usually differed. When inflamed animals were given indomethacine, a clear-cut difference in the concentration of some proteins was observed versus inflamed rats not given medication, at 24 h after the start of the treatments. Proteins mainly affected were alpha2-macroglobulin, alpha2-HS-glycoprotein, C-reactive protein and kallikrein-binding protein.

Proteins of rat serum: I. Establishing a reference two-dimensional electrophoresis map by immunodetection and microbore high performance liquid chromatography-electrospray mass spectrometry

In the present investigation, we have identified 56 major spots, or spot rows, corresponding to 22 proteins, in the 2-DE pattern of adult male rats. This was done mainly by applying two complementary techniques, namely immunoblotting and high performance liquid chromatography-mass spectrometry (HPLC-MS) peptide mapping. Glycoproteins were characterized by affinity blotting with six lectins. We have also detailed how rat serum differs from human serum in two main respects: (i) relative abundance of individual proteins, which amounts in some cases to a complete absence in either sample, and (ii) varying molecular parameters for homologous proteins. It was thus possible to establish a first-generation reference map of rat serum proteins, which can be accessed through http://weber.u.washington.edu/ruedilab/aebersold++ +.html. We hope the present database will be a useful reference for the evaluation of changes in serum protein distribution in the course of pharmacological and toxicological studies. The recognition of species-specific proteins appears of special relevance in this respect.

Biomedical relevance of two-dimensional protein mapping

State-of-the-art and future perspectives are discussed for the application of two-dimensional protein maps to basic medical research and routine clinical chemistry problems. Despite the technical advances that allow effective processing of a large number of samples and the refinement of devices and procedures for image analysis, at present two-dimensional maps are mostly confined to research purposes, i.e. to the inventory of normal constituents of body fluids and tissues on the one hand, and to qualitative-quantitative alterations of some protein spots in a number of instances (genetic, degenerative, infectious or xenobiotic diseases) on the other. It is hoped that in some instances a single primarily affected component will be able to be identified and then specifically tested (for instance by immunological means) as a diagnostic marker, but complex pathological patterns would still require the analysis of a large number of peptides at the resolution level only afforded by two dimensions. Further simplification of the protocols, for example with ready-made gels, and data reduction systems might then allow the application of the technique to be extended to general clinical laboratories.

Serum proteins of rats exposed to organic solvents examined by horizontal two-dimensional electrophoresis with an immobilized pH gradient in the first dimension

Serum proteins of rats, exposed to methoxyethylacetate and a combination of methoxyethylacetate and isobutylacetate, were analyzed by horizontal high resolution two-dimensional gel electrophoresis with immobilized pH gradients in the first dimension. A total of 410 polypeptides were detected with either increasing or decreasing spot intensities after rat exposure to the organic solvents.

Separation of different forms of transferrin by isoelectric focusing to detect effects on the liver caused by xenobiotics

Several genetic variants and also isoforms of transferrin differing in carbohydrate structure can be separated by polyacrylamide or agarose gel isoelectric focusing. Numerous blood plasma or serum samples can be analyzed in parallel in each gel. Studies of the heterogeneity of transferrin have already revealed many results of importance to different fields of human medicine. Gene typing can give important and useful information for paternity determination and in forensic medicine. The gene type C 2 seems to have increased frequency in certain malfunctions. Futhermore, functional abnormalities of liver cells can be revealed by determination of the concentrations of transferrin isoforms differing mainly in their carbohydrate parts. The isoforms can be quantified with zone immunoelectrophoresis assay. Thus valuable information can be obtained about important modulated regulations of cell and membrane functions, even when these are disturbed by disease and xenobiotics. The information may be useful e.g. in the detection of individuals suffering from toxic effects, to identify toxic agents and exposure conditions. Studies of house painters revealed that exposure to different types of paints had an effect on transferrin. Determination of the concentration of the isotransferrin with pI 5.7 in blood samples from alcoholics can be used as a marker for the detection of liver dysfunction and for the monitoring of therapy treatments. In addition, by analyzing the isotransferrins a rare genetic abnormality can be detected.

Two-dimensional gel electrophoresis of proteins

The high-resolution capacity of two-dimensional polyacrylamide gel electrophoresis (2-D PAGE) makes it an excellent tool for the analysis and characterisation of complex protein mixtures. The evolution of two-dimensional electrophoresis is briefly described. The various steps involved in 2-D PAGE, the identification and characterization of proteins separated by 2-D PAGE and the quantitative and qualitative analysis of 2-D patterns are discussed in detail and some new approaches are described. In the final section a brief outline of some of the biomedical applications of 2-D PAGE to screening of body fluids, genetic diseases, inborn errors of metabolism, cancer and neoplastic transformation are discussed.