Proteomic and transcriptomic analysis of heart failure due to volume overload in a rat aorto-caval fistula model provides support for new potential therapeutic targets - monoamine oxidase A and transglutaminase 2

<p>Abstract</p> <p>Background</p> <p>Chronic hemodynamic overloading leads to heart failure (HF) due to incompletely understood mechanisms. To gain deeper insight into the molecular pathophysiology of volume overload-induced HF and to identify potential markers and targets for novel therapies, we performed proteomic and mRNA expression analysis comparing myocardium from Wistar rats with HF induced by a chronic aorto-caval fistula (ACF) and sham-operated rats harvested at the advanced, decompensated stage of HF.</p> <p>Methods</p> <p>We analyzed control and failing myocardium employing iTRAQ labeling, two-dimensional peptide separation combining peptide IEF and nano-HPLC with MALDI-MS/MS. For the transcriptomic analysis we employed Illumina RatRef-12v1 Expression BeadChip.</p> <p>Results</p> <p>In the proteomic analysis we identified 2030 myocardial proteins, of which 66 proteins were differentially expressed. The mRNA expression analysis identified 851 differentially expressed mRNAs.</p> <p>Conclusions</p> <p>The differentially expressed proteins confirm a switch in the substrate preference from fatty acids to other sources in the failing heart. Failing hearts showed downregulation of the major calcium transporters SERCA2 and ryanodine receptor 2 and altered expression of creatine kinases. Decreased expression of two NADPH producing proteins suggests a decreased redox reserve. Overexpression of annexins supports their possible potential as HF biomarkers. Most importantly, among the most up-regulated proteins in ACF hearts were monoamine oxidase A and transglutaminase 2 that are both potential attractive targets of low molecular weight inhibitors in future HF therapy.</p

The core components of organelle biogenesis and membrane transport in the hydrogenosomes of Trichomonas vaginalis

Trichomonas vaginalis is a parasitic protist of the Excavata group. It contains an anaerobic form of mitochondria called hydrogenosomes, which produce hydrogen and ATP; the majority of mitochondrial pathways and the organellar genome were lost during the mitochondrion-to-hydrogenosome transition. Consequently, all hydrogenosomal proteins are encoded in the nucleus and imported into the organelles. However, little is known about the membrane machineries required for biogenesis of the organelle and metabolite exchange. Using a combination of mass spectrometry, immunofluorescence microscopy, in vitro import assays and reverse genetics, we characterized the membrane proteins of the hydrogenosome. We identified components of the outer membrane (TOM) and inner membrane (TIM) protein translocases include multiple paralogs of the core Tom40-type porins and Tim17/22/23 channel proteins, respectively, and uniquely modified small Tim chaperones. The inner membrane proteins TvTim17/22/23-1 and Pam18 were shown to possess conserved information for targeting to mitochondrial inner membranes, but too divergent in sequence to support the growth of yeast strains lacking Tim17, Tim22, Tim23 or Pam18. Full complementation was seen only when the J-domain of hydrogenosomal Pam18 was fused with N-terminal region and transmembrane segment of the yeast homolog. Candidates for metabolite exchange across the outer membrane were identified including multiple isoforms of the &beta;-barrel proteins, Hmp35 and Hmp36; inner membrane MCF-type metabolite carriers were limited to five homologs of the ATP/ADP carrier, Hmp31. Lastly, hydrogenosomes possess a pathway for the assembly of C-tail-anchored proteins into their outer membrane with several new tail-anchored proteins being identified. These results show that hydrogenosomes and mitochondria share common core membrane components required for protein import and metabolite exchange; however, they also reveal remarkable differences that reflect the functional adaptation of hydrogenosomes to anaerobic conditions and the peculiar evolutionary history of the Excavata group