Proteomics in myocardial diseases

Proteomics of the heart

Mass spectrometry-based proteomics is a sophisticated identification tool specializing in portraying protein dynamics at a molecular level. Proteomics provides biologists with a snapshot of context-dependent protein and proteoform expression, structural conformations, dynamic turnover, and protein-protein interactions. Cardiac proteomics can offer a broader and deeper understanding of the molecular mechanisms that underscore cardiovascular disease, and it is foundational to the development of future therapeutic interventions. This review encapsulates the evolution, current technologies, and future perspectives of proteomic-based mass spectrometry as it applies to the study of the heart. Key technological advancements have allowed researchers to study proteomes at a single-cell level and employ robot-assisted automation systems for enhanced sample preparation techniques, and the increase in fidelity of the mass spectrometers has allowed for the unambiguous identification of numerous dynamic posttranslational modifications. Animal models of cardiovascular disease, ranging from early animal experiments to current sophisticated models of heart failure with preserved ejection fraction, have provided the tools to study a challenging organ in the laboratory. Further technological development will pave the way for the implementation of proteomics even closer within the clinical setting, allowing not only scientists but also patients to benefit from an understanding of protein interplay as it relates to cardiac disease physiology.

Functional proteomic analysis of experimental autoimmune myocarditis-induced chronic heart failure in the rat

Experimental autoimmune myocarditis (EAM)-induced heart failure in rats is used to study the pathogenesis of heart failure. Based on a proteomic analysis of soluble (S) and membranous (M) fractions extracted from ventricles of rats with a stable chronic form of EAM-induced heart failure, we assessed changes in protein levels and their correlation to heart functions to gain insights into the pathogenesis and to explore new targets for the treatment of heart failure. Proteins were separated by two-dimensional gel electrophoresis and silver stained spots were analyzed. In the S-fraction, 274+/-3 spots were detected in the normal (N)-group and 273+/-6 in the heart failure (HF)-group. In the HF-group, 26 of the spots were increased and 15 were decreased in intensity. In the M-fraction, 277+/-3 spots were detected in the N-group and 277+/-2 in the HF-group, with 20 spots increased and 10 decreased in intensity. We analyzed relationships between the expression of these proteins and 11 parameters of heart function, and found all the significantly changed spots to correlate with at least one of the parameters. We analyzed 49 spots that correlated with over 9 parameters of heart function using mass spectrometry, and identified 15 as proteins with increased expression including glucose regulated protein (GRP)78, an endoplasmic-stress related protein, and heat shock protein (HSP)90beta, a molecular chaperone, and 4 spots as proteins with decreased expression. It is suggested that in the heart failure model, GRP78 and HSP90beta play a role in the protection or deterioration of the heart and may be new targets for treatment.

Elucidation of the molecular mechanisms of preeclampsia using proteomic technologies

Preeclampsia, a disease of pregnancy, is a multisystem disorder associated with elevated maternal blood pressure, proteinurea, oedema, and fetal abnormalities. It is a major cause of mortality, morbidity, perinatal death, and premature delivery. Despite active research in the past decade, there is yet no definitive cure for preeclampsia. The disease has been treated symptomatically with antihypertensives, antieclamptics, bed rest, and a whole gamut of isolated therapies. In an attempt to understand the molecular basis of this disease and many other fatal diseases including cancer and heart disease, the scientific community has been turning to understanding the genome and more lately the "proteome". Proteomics enables researchers to identify all proteins expressed in a cell or organ and detect any PTM in the protein expression patterns. Deciphering the placental proteome and studying the differences in protein expression patterns in the normal as against the preeclamptic proteome might possibly in future lead to early detection and therapeutic targeting of preeclampsia.

Genomic medicine: genetic variation and its impact on the future of health care

Advances in genome technology and other fruits of the Human Genome Project are playing a growing role in the delivery of health care. With the development of new technologies and opportunities for large-scale analysis of the genome, transcriptome, proteome and metabolome, the genome sciences are poised to have a profound impact on clinical medicine. Cancer prognostics will be among the first major test cases for a genomic medicine paradigm, given that all cancer is caused by genomic instability, and microarrays allow assessment of patients' entire expressed genomes. Analysis of breast cancer patients' expression patterns can already be highly correlated with recurrence risks. By integrating clinical data with gene expression profiles, imaging, metabolomic profiles and proteomic data, the prospect for developing truly individualized care becomes ever more real. Notwithstanding these promises, daunting challenges remain for genomic medicine. Success will require planning robust prospective trials, analysing health care economic and outcome data, assuaging insurance and privacy concerns, developing health delivery models that are commercially viable and scaling up to meet the needs of the whole population.

Mass Spectrometric Peptide Fingerprinting of Proteins after Western Blotting on Polyvinylidene Fluoride and Enhanced Chemiluminescence Detection

The combined use of sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE) and mass spectrometry has become a powerful and widely used tool in proteome studies. Following separation by electrophoresis, proteins can be transferred to an inert support such as polyvinylidene fluoride (PVDF) or nitrocellulose (NC) for the visualization of individual or specific classes of proteins by immunochemical detection methods. We developed a method that allows the mass spectrometric analysis of peptides derived from proteins detected by Western blotting on PVDF. Proteolysis buffer containing either dimethyl formamide (DMF) or Triton X-100 to recover peptides amenable to mass spectrometry was investigated. Although either one can be used, the buffer containing DMF required less sample handling prior to mass spectrometry. The approach was tested using commercially available proteins and serine-phosphorylated proteins from an HEK-293 nuclear extract.

Laboratory diagnosis of acute myocardial injury

Considerable effort by clinicians and scientists focuses on the utility of biomarkers to prevent, diagnose and manage adverse cardiac events as well as provide information on a specific patient's underlying pathology. Although troponins I and T (TnI and TnT) are cardiac specific markers that yield diagnostic and prognostic value in patients with myocardial injury, troponins cannot be utilized in all clinical settings. Troponins have limited utility for the diagnosis of early ischemia and preoperative myocardial infarction. Troponin T also lacks specificity in patients with renal failure. New markers, such as ischemia modified albumin (IMA) and CD40 ligand, and new technologies, such as proteomics, are under investigation to advance our knowledge of heart disease.

Proteomics in pathology, research and practice

Using more reliable and sophisticated protein biochemical techniques, it is possible to perform large scale, partly high-throughput characterization of the human proteome. Two-dimensional electrophoresis (2-DE) and mass spectrometry largely contribute to the identification of proteins and peptides. 2-DE has been used to study differential expression of peptides and proteins in various disease entities, searching for new diagnostic and therapeutic targets. However, 2-DE usually requires large amounts of starting material, is time-consuming, and reveals only a fraction of the proteins present in a given sample. More recently, the ProteinChip technology coupled with bioinformatics has gained considerable attention. This technique uses surface-enhanced laser desorption/ionization time-of-flight mass spectrometry (SELDI TOF/MS) to screen any protein source for putative disease biomarkers in a spectrum from 2 to 20 kDa. Between 15,500 (low resolution SELDI TOF) and > 400,000 peptides and proteins (high-resolution SELDI-TOF) can be resolved from a small sample volume (microl-range). Several studies have provided evidence that ProteinChip technology is capable of detecting early stage cancer by its unique cancer-specific proteomic finger prints, with sensitivities and specificities reaching far beyond well established serum-based tumor markers. In this review, we summarize the recent developments of proteomics in research and pathology, and critically discuss putative limitations and future applications of disease-specific biomarkers. Special emphasis is put on the former Human Protein Index project.