Pilot proteomic profile of differentially regulated proteins in right atrial appendage before and after cardiac surgery using cardioplegia and cardiopulmonary bypass

Overexpression of the PTEN Gene in Myocardial Tissues of Coronary Bypass Surgery Patients

BACKGROUND

Coronary artery disease is a complex disorder that causes death worldwide. One of the genes involved in developing this disease may be PTEN.

OBJECTIVES

This study aimed to investigate the PTEN gene and protein expression in tissue and blood samples taken from coronary bypass surgery patients.

METHODS

Molecular studies were performed at Erciyes University Genome and Stem Cell Center (GENKOK). Right atrial appendage and blood samples were taken from the central vein of 22 coronary bypass surgery patients before starting and ending cardiopulmonary bypass. PTEN expression was determined using quantitative real-time PCR and western blot analysis. The significance level was accepted as p<0.05.

RESULTS

There was no significant difference in the PTEN gene expression in blood samples taken before and after cardiopulmonary bypass. However, a substantial increase in both protein and gene expression levels of P-PTEN and PTEN was observed in the tissue samples. Myocardial expression of the PTEN gene was significantly increased at the end of the cardiopulmonary bypass. PTEN gene expression in the post-cardiopulmonary bypass period was increased when compared to the pre-bypass period, but it was insignificant when compared to healthy controls.

CONCLUSION

This study first revealed the role of the PTEN gene by analyzing both mRNA and protein expression in coronary bypass patients, appearing in both myocardial tissue and blood samples. Increased levels of PTEN may be a marker in myocardial tissue for patients with coronary artery disease.

Isolation of Mitochondrial DNA from Single, Short Hairs without Roots Using Pressure Cycling Technology

Hairs are commonly submitted as evidence to forensic laboratories, but standard nuclear DNA analysis is not always possible. Mitochondria (mt) provide another source of genetic material; however, manual isolation is laborious. In a proof-of-concept study, we assessed pressure cycling technology (PCT; an automated approach that subjects samples to varying cycles of high and low pressure) for extracting mtDNA from single, short hairs without roots. Using three microscopically similar donors, we determined the ideal PCT conditions and compared those yields to those obtained using the traditional manual micro-tissue grinder method. Higher yields were recovered from grinder extracts, but yields from PCT extracts exceeded the requirements for forensic analysis, with the DNA quality confirmed through sequencing. Automated extraction of mtDNA from hairs without roots using PCT could be useful for forensic laboratories processing numerous samples.

Cardiopulmonary bypass changes the plasma proteome in children undergoing tetralogy of Fallot repair

Introduction:

Cardiopulmonary bypass (CPB) can be associated with deleterious clinical effects. However, the impact of CPB on inflammatory, immunological and other homeostatic pathways remains poorly understood. We investigated the impact of CPB on the plasma proteome in children undergoing tetralogy of Fallot repair.

Methods:

Blood samples were taken from 20 children prior to and at the end of CPB and 6h, 12h and 24h after CPB. Plasma was analysed by liquid chromatography-mass spectrometry (LC-MS) in a label-free, untargeted approach. Data were analysed using Genedata software to identify peptides that were differentially expressed (p<0.01 above a false discovery rate). Proteins were identified from peptides that demonstrated differential expression.

Results:

The proteins that were found to be differentially expressed were haptoglobin isoform 1 preproprotein, isoform 2 of semaphorin-6C, vitamin D-binding protein, inter-alpha-trypsin inhibitor, ceruloplasmin, apolipoprotein B100 and fibrinogen alpha.

Conclusion:

CPB alters the plasma proteome with differences most apparent at 6h and 12h post CPB. There was a return to baseline with no proteins differentially regulated by 24h.

Proteomic Profiling of Early Chronic Pulmonary Hypertension: Evidence for Both Adaptive and Maladaptive Pathology

Background

The molecular mechanisms governing right atrial (RA) and ventricular (RV) hypertrophy and failure in chronic pulmonary hypertension (CPH) remain unclear. The purpose of this investigation was to characterize RA and RV protein changes in CPH and determine their adaptive versus maladaptive role on hypertrophic development.

Methods

Nine dogs underwent sternotomy and RA injection with 3 mg/kg dehydromonocrotaline (DMCT) to induce CPH (n=5) or sternotomy without DMCT (n=4). At 8-10 weeks, RA and RV proteomic analyses were completed after trypsinization of cut 2-D gel electrophoresis spots and peptide sequencing using mass spectrometry.

Results

In the RV, 13 protein spots were significantly altered with DMCT compared to Sham. Downregulated RV proteins included contractile elements: troponin T and C (-1.6 fold change), myosin regulatory light chain 2 (-1.9), cellular energetics modifier: fatty-acid binding protein (-1.5), and (3) ROS scavenger: superoxide dismutase 1 (-1.7). Conversely, beta-myosin heavy chain was upregulated (+1.7). In the RA, 22 proteins spots were altered including the following downregulated proteins contractile elements: tropomyosin 1 alpha chain (-1.9), cellular energetic proteins: ATP synthase (-1.5), fatty-acid binding protein (-2.5), and (3) polyubiquitin (-3.5). Crystallin alpha B (hypertrophy inhibitor) was upregulated in both the RV (+2.2) and RA (+2.6).

Conclusions

In early stage hypertrophy there is adaptive upregulation of major RA and RV contractile substituents and attenuation of the hypertrophic response. However, there are multiple indices of maladaptive pathology including considerable cellular stress associated with aberrancy of actin machinery activity, decreased efficiency of energy utilization, and potentially decreased protein quality control.

The long pentraxin PTX3: a candidate anti-inflammatory mediator in cardiac surgery

Coronary artery bypass grafting (CABG) is performed with the use of cardiopulmonary bypass (CPB) and cardioplegic arrest (CA) of the heart. The advantage of this technique, alternatively referred to as “on-pump” surgery, resides, for the surgeon, in relatively easy access to and manipulation with the non-beating, bloodless heart. However, the advantage that is, thereby, gained by the patient is paid off by an increased susceptibility to postoperative systemic inflammatory response syndrome (SIRS). Under unfavorable conditions, the inflammatory syndrome may develop into life-threatening forms of MODS (multiple organ dysfunction syndrome) or even MOFS (multiple organ failure syndrome). Deliberate avoidance of CPB, also known as “off-pump” surgery, attenuates early postoperative inflammation throughout its trajectory of SIRS→MODS→MOFS, but, in the long run, there appears to be no substantial difference in the overall mortality rates. In the last years, our knowledge of the pathophysiology of surgical inflammation has increased considerably. Recent findings, highlighting the as yet rather obscure role of pentraxin 3 (PTX3) in these processes, are discussed in this review article.

Microarray and proteomic analysis of the cardioprotective effects of cold blood cardioplegia in the mature and aged male and female

Recently we have shown that the cardioprotection afforded by cardioplegia is modulated by age and gender and is significantly decreased in the aged female. In this report we use microarray and proteomic analyses to identify transcriptomic and proteomic alterations affecting cardioprotection using cold blood cardioplegia in the mature and aged male and female heart. Mature and aged male and female New Zealand White rabbits were used for in situ blood perfused cardiopulmonary bypass. Control hearts received 30 min sham ischemia and 120 min sham reperfusion. Global ischemia (GI) hearts received 30 min of GI achieved by cross-clamping of the aorta. Cardioplegia (CP) hearts received cold blood cardioplegia prior to GI. Following 30 min of GI the hearts were reperfused for 120 min and then used for RNA and protein isolation. Microarray and proteomic analyses were performed. Functional enrichment analysis showed that mitochondrial dysfunction, oxidative phosphorylation and calcium signaling pathways were significantly enriched in all experimental groups. Glycolysis/gluconeogenesis and the pentose phosphate pathway were significantly changed in the aged male only (P < 0.05), while glyoxylate/dicarboxylate metabolism was significant in the aged female only (P < 0.05). Our data show that specific pathways associated with the mitochondrion modulate cardioprotection with CP in the aged and specifically in the aged female. The alteration of these pathways significantly contributes to decreased myocardial functional recovery and myonecrosis following ischemia and may be modulated to allow for enhanced cardioprotection in the aged and specifically in the aged female.

Pressure cycling technology in systems biology

Systems biologists frequently seek to integrate complex data sets of diverse analytes into a comprehensive picture of an organism's biological state under defined environmental conditions. Although one would prefer to collect these data from the same sample, technical limitations with traditional sample preparation methods often commit the investigator to extracting one type of analyte at the expense of losing all others. Often, volume further constrains the range of experiments that can be collected from a single sample. The practical solution employed to date has been to rely on information collected from multiple replicate experiments and similar historical or reported data. While this approach has been popular, the integration of information collected from disparate single-analyte sample preparation streams increases uncertainty due to nonalignment during comparative analysis, and such gaps accumulate quickly when combining multiple data sets. Regrettably, discontinuities between separate data streams can confound a whole understanding of the biological system being investigated. This difficulty is further compounded for researchers handling highly pathogenic samples, in which it is often necessary to use harsh chemicals or high-energy sterilization procedures that damage the target analytes. Ultra-high pressure cycling technology (PCT), also known as barocycling, is an emerging sample preparation strategy that has distinct advantages for systems biology studies because it neither commits the researcher to pursuing a specific analyte nor leads to the degradation of target material. In fact, samples prepared under pressure cycling conditions have been shown to yield a more complete set of analytes due to uniform disruption of the sample matrix coupled with an advantageous high pressure solvent environment. Fortunately, PCT safely sterilizes and extracts complex or pathogenic viral, bacterial, and spore samples without adversely affecting the constituent biomolecules valued as informative and meaningful analytes. This chapter provides procedures and findings associated with incorporating PCT into systems biology as a new and enabling approach to preanalytical sample treatment.

Using tandem mass spectrometry in targeted mode to identify activators of class IA PI3K in cancer

Phosphatiditylinositide-3-kinase (PI3K) is activated in some cancers by direct mutation, but it is activated more commonly in cancer by mutation of upstream acting receptor tyrosine kinases (TK). At present, there is no systematic method to determine which TK signaling cascades activate PI3K in certain cancers, despite the likely utility of such information to help guide selection of tyrosine kinase inhibitor (TKI) drug strategies for personalized therapy. Here, we present a quantitative liquid chromatography tandem mass spectrometry approach that identifies upstream activators of PI3K both in vitro and in vivo. Using non-small cell lung carcinoma to illustrate this approach, we show a correct identification of the mechanism of PI3K activation in several models, thereby identifying the most appropriate TKI to downregulate PI3K signaling. This approach also determined the molecular mechanisms and adaptors required for PI3K activation following inhibition of the mTOR kinase TORC1. We further validated the approach in breast cancer cells with mutational activation of PIK3CA, where tandem mass spectrometry detected and quantitatively measured the abundance of a helical domain mutant (E545K) of PIK3CA connected to PI3K activation. Overall, our findings establish a mass spectrometric approach to identify functional interactions that govern PI3K regulation in cancer cells. Using this technique to define the pathways that activate PI3K signaling in a given tumor could help inform clinical decision making by helping guide personalized therapeutic strategies for different patients.

p38 MAPK-dependent small HSP27 and αB-crystallin phosphorylation in regulation of myocardial function following cardioplegic arrest

We previously demonstrated that myocardial p38 mitogen-activated protein kinase (MAPK) and heat shock protein 27 (HSP27) are phosphorylated following cardioplegic arrest in patients undergoing cardiac surgery and correlate with reduced cardiac function. The following studies were performed to determine whether inhibition of p38 MAPK and/or overexpression of nonphosphorylatable HSP27 improves cardiac function following cardioplegic arrest. Langendorff-perfused isolated rat hearts were subjected to 2 h of intermittent cold cardioplegia followed by 30 min of reperfusion. Hearts were treated with (CP+SB) or without (CP) the p38 MAPK inhibitor SB-203580 (5 μM) supplied in the cardioplegia. Sham-treated hearts served as controls. In separate experiments, isolated rat ventricular myocytes infected with either green fluorescent protein (GFP) or a nonphosphorylatable HSP27 mutant (3A-HSP27) were subjected to 3 h of cold hypoxic cardioplegia and simulated reperfusion (CP) followed by video microscopy and length change measurements. Baseline parameters of cardiac function were similar between groups [left ventricular developed pressure (LVDP), 119 ± 4.9 mmHg; positive and negative first derivatives of LV pressure (± dP/dt), 3,139 ± 245 and 2, 314 ± 110 mmHg/s]. CP resulted in reduced cardiac function (LVDP, 72.2 ± 5.8 mmHg; ± dP/dt, 2,076 ± 231 and -1,317 ± 156 mmHg/s) compared with baseline. Treatment with 5 μM SB-203580 significantly improved CP-induced cardiac function (LVDP, 101.9 ± 0 mmHg; ± dP/dt, 2,836 ± 163 and -2,108 ± 120 mmHg/s; P = 0.03, 0.01, and 0.04, CP+SB vs. CP). Inhibition of p38 MAPK significantly lowered CP-induced p38 MAPK, HSP27, and αB-crystallin (cryAB) phosphorylation. In vitro CP decreased myocyte length changes from 10.3 ± 1.5% (GFP) to 5.7 ± 0.8% (GFP+CP). Infection with 3A-HSP27 completely rescued CP-induced decreased myocyte contraction (11.1 ± 1.0%). However, infection with 3A-HSP27 did not block the endogenous HSP27 response. We conclude that inhibition of p38 MAPK and subsequent HSP27 and cryAB phosphorylation and/or overexpression of nonphosphorylatable HSP27 significantly improves cardiac performance following cardioplegic arrest. Modulation of HSP27 phosphorylation may improve myocardial stunning following cardiac surgery.