Alterations in rabbit kidney protein expression following lead exposure as analyzed by two-dimensional gel electrophoresis

Long-Term Exposure of Lead Acetate on Rabbit Renal Tissue

Background:

Lead has been widely used in different industries for ages. It is one of the heavy metals, highly poisonous even at low doses, and has biochemical, physiological and behavioral side effects on human and animals. It has been shown that lead has toxic effects on different tissues such as neural and genitourinary tissues, cardiovascular systems and blood. Therefore, high attention has been paid to its environmental pollutions.

Objectives:

Although many histological and biochemical studies have reported about the effects of lead on the renal tissue, there are a few studies about the ultrastructure and morphometric effects of lead on the kidney. Hence, the aim of this study was the evaluation of morphology and morphometrics of rabbit renal urinary barrier ultrastructure following long-term exposure to lead acetate.

Materials and Methods:

In this experimental study, 20 male New Zealand rabbits were divided into control and test groups (10 in each). The test group was injected intraperitoneally with chronic dose (8.5 mg/kg of body weight) of lead acetate and for the control group the same volume of normal saline was used, every other day for 10 weeks. After anesthetizing, the biopsies of renal tissues were taken for light and electron microscopic morphometric and morphologic analyses.

Results:

Long-term exposure to lead acetate caused histopathology effects including dilatation, congestion, nuclei heterochromatic effects, increase in diameter of renal tubules and urinary barrier thickness in rabbit renal tissue.

Conclusions:

Quantitative and qualitative results of long-term lead acetate exposure showed many histopathology side-effects, especially in the urinary barrier.

Proteomics in renal research

Proteomic technologies are used with increasing frequency in the renal community. In this review, we highlight the use in renal research of a number of available techniques including two-dimensional gel electrophoresis, liquid chromatography/mass spectrometry, surface-enhanced laser desorption/ionization, capillary electrophoresis/mass spectrometry, and antibody and tissue arrays. These techniques have been used to identify proteins or changes in proteins specific to regions of the kidney or associated with renal diseases or toxicity. They have also been used to examine protein expression changes and posttranslational modifications of proteins during signaling. A number of studies have used proteomic methodologies to look for diagnostic biomarkers in body fluids. The rapid rate of development of the technologies along with the combination of classic physiological and biochemical techniques with proteomics will enable new discoveries.

Towards the application of proteomics in renal disease diagnosis

Proteomics is widely envisioned as playing a significant role in the translation of genomics to clinically useful applications, especially in the areas of diagnostics and prognostics. In the diagnosis and treatment of kidney disease, a major priority is the identification of disease-associated biomarkers. Proteomics, with its high-throughput and unbiased approach to the analysis of variations in protein expression patterns (actual phenotypic expression of genetic variation), promises to be the most suitable platform for biomarker discovery. Combining such classic analytical techniques as two-dimensional gel electrophoresis with more sophisticated techniques, such as MS, has enabled considerable progress to be made in cataloguing and quantifying proteins present in urine and various kidney tissue compartments in both normal and diseased physiological states. Despite these accomplishments, there remain a number of important challenges that will need to be addressed in order to pave the way for the universal acceptance of proteomics as a clinically relevant diagnostic tool. We discuss issues related to three such critical developmental tasks as follows: (i) completely defining the proteome in the various biological compartments (e.g. tissues, serum and urine) in both health and disease, which presents a major challenge given the dynamic range and complexity of such proteomes; (ii) achieving the routine ability to accurately and reproducibly quantify proteomic expression profiles; and (iii) developing diagnostic platforms that are readily applicable and technically feasible for use in the clinical setting that depend on the fruits of the preceding two tasks to profile multiple disease biomarkers.

The use of animal models in expression pharmacogenomic analyses

Expression pharmacogenomics applies genome/proteome scale differential expression technologies to both in vivo and in vitro models of drug response to identify candidate markers correlative with and predictive of drug toxicity and efficacy. It is anticipated to streamline drug development by triaging towards lead compounds and clinical candidates that maximize efficacy while minimizing safety risks. As the majority of expression pharmacogenomics will be performed on preclinical therapeutic candidates, compatibility with favored preclinical animal model systems will be essential. This review will address expression pharmacogenomics in the context of those animal model systems commonly used for pharmacokinetic, pharmacodynamic and toxicologic analyses. Specific discussions will cover: (A) relative robustness of genomic and proteomic technology platforms used to generate drug response data in critical model systems; (B) animal handling, treatment and other experimental design optimizations; (C) data analysis strategies for extracting and validating candidate pharmacogenomic markers; and (D) overarching limitations in applying expression pharmacogenomics to animal model systems.

Toxicoproteomics -- a new preclinical tool

The publication of the human genome has presented the scientific community with an unprecedented amount of genetic information with the potential to revolutionize the drug discovery process. This information could be used to identify novel drug targets and disease markers or could aid in the development of personalized medicines. The realization that genetic changes must ultimately influence protein function has pushed the field of proteomics further into the limelight. In this review the applications of proteomics to the field of toxicology will be discussed. It is anticipated that, in the future, toxicologists will apply a range of genomic and proteomic techniques to address issues in toxicity.

Proteomics--post-genomic cartography to understand gene function

The completion of the genomic sequences of numerous organisms from human and mouse to Caenorhabditis elegans and many microorganisms, and the definition of their genes provides a database to interpret cellular protein-expression patterns and relate them to protein function. Proteomics technologies that are dependent on mass spectrometry and involve two-dimensional gel electrophoresis are providing the main window into the world of differential protein-expression analysis. In this article, the limitations and expectations of this research field are examined and the future of the analytical needs of proteomics is explored.

Proteomics: applications in basic and applied biology

The rapid evolution of proteomics has continued during the past year, with a series of innovations in the core technologies of two-dimensional electrophoresis and mass spectrometry, and a diversity of productive research programmes. Well-annotated proteomics databases are now emerging in a number of fields to provide a platform for systematic research, with particularly promising progress in clinical applications such as cardiology and oncology. Large-scale quantitative research, comparable in power and sensitivity to that achieved for gene expression, is thus becoming a reality at the protein level.

Genomics and proteomics: the new millennium of drug discovery and development

One of the most pressing issues facing the pharmaceutical and biotechnology industry is the tremendous dropout rate of lead drug candidates. Over the last two decades, several new genomic technologies have been developed in hopes of addressing the issues of target identification and lead candidate optimization. Gene expression microarray is one of these technologies and this review describes the four main formats, which are currently available: (a) cDNA; (b) oligonucleotide; (c) electrokinetic; and (d) fiberoptic. Many of these formats have been developed with the goal of screening large numbers of genes. Recently, a high-throughput array format has been developed where a large number of samples can be assayed using arrays in parallel. In addition, focusing on gene expression may be only one avenue in preventing lead candidate failure. Proteomics or the study of protein expression may also play a role. Two-dimensional polyacrylamide gel electrophoresis (2-DE) coupled with mass spectroscopy has been the most widely accepted format to study protein expression. However, protein microarrays are now being developed and modified to a high-throughput screening format. Examples of several gene and protein expression studies as they apply to drug discovery and development are reviewed. These studies often result in large data sets. Examples of how several statistical methods (principal components analysis [PCA], clustering methods, Shannon entropy, etc.) have been applied to these data sets are also described. These newer genomic and proteomic technologies and their analysis and visualization methods have the potential to make the drug discovery and development process less costly and more efficient by aiding to select better target and lead candidates.

Current awareness

In order to keep subscribers up-to-date with the latest developments in their field, this current awareness service is provided by John Wiley & Sons and contains newly-published material on comparative and functional genomics. Each bibliography is divided into 16 sections. 1 Reviews & symposia; 2 General; 3 Large-scale sequencing and mapping; 4 Genome evolution; 5 Comparative genomics; 6 Gene families and regulons; 7 Pharmacogenomics; 8 Large-scale mutagenesis programmes; 9 Functional complementation; 10 Transcriptomics; 11 Proteomics; 12 Protein structural genomics; 13 Metabolomics; 14 Genomic approaches to development; 15 Technological advances; 16 Bioinformatics. Within each section, articles are listed in alphabetical order with respect to author. If, in the preceding period, no publications are located relevant to any one of these headings, that section will be omitted