Comparative proteomic analysis of rat left ventricle in a subtotal nephrectomy model.

BACKGROUND: Chronic kidney disease (CKD) is associated with cardiac hypertrophy that leads to increased cardiovascular morbidity and mortality. To date, use of the renin-angiotensin-aldosterone system blockade has been the main treatment modality. However, renin-angiotensin-aldosterone system blockade by the angiotensin converting enzyme inhibitors (ACEi) can only partially reverse the cardiac hypertrophy without having a significant impact on all-cause mortality as evidenced by meta-analyses from clinical trials. It is imperative to elucidate the molecular pathogenesis of CKD-related cardiomyopathy for potential targets in further treatment. METHODS: Male Sprague-Dawley rats that underwent subtotal nephrectomy (SNX) rats were established as the CKD model. A hemodynamic study was used to evaluate the left ventricle (LV) structural and functional alterations. We used proteomic techniques to profile the LV protein changes among sham-operated rats, SNX rats, and SNX rats with 6 months of ACEi enalapril interventions. The differentially expressed proteins were further annotated by functional and network analyses. RESULTS: As compared to the sham-operated rats, the SNX rats had 25 upregulated and 46 decreased protein expression. The top canonical pathways identified by ingenuity pathway analysis for the CKD cardiomyopathy were mitochondrial dysfunction, oxidative phosphorylation, fatty acid ß oxidation, protein ubiquitination, and ketolysis. The most relevant functions extracted from these networks contained 27 and 23 focused proteins, respectively. They were related to cellular assembly and organization, RNA posttranscriptional modification, and protein synthesis. After ACEi intervention for 6 weeks, the residual canonical pathways identified by ingenuity pathway analysis that mediated the CKD-related cardiomyopathy were mitochondrial dysfunction, ketolysis, phenylalanine degradation IV, and putrescine degradation III. There were decreased Sirt3 and SNRNP, and increased monoamine oxidase and SAHH expression in the LV of SNX rats that could not be reversed by the ACEi. CONCLUSION: Our studies provide a repertoire of potential biomarkers related to cardiac hypertrophy in CKD. There are still residual disturbed molecules/pathways despite ACEi intervention. Further studies are warranted to investigate these potential novel targets to alleviate CKD-related cardiomyopathy.

Comparative proteomic analysis of rat aorta in a subtotal nephrectomy model.

Although accelerated atherosclerosis and arteriosclerosis are the main causes of cardiovascular morbidity and mortality in chronic kidney disease (CKD) patients, the molecular pathogenesis remains largely obscure. Our study of the aortic function in a typical CKD model of subtotal nephrectomy (SNX) rats demonstrated phenotypes that resemble CKD patients with aortic stiffness. The 2-DE analysis of rat aortas followed by MS identified 29 up-regulated and 53 down-regulated proteins in SNX rats. Further Western blot and immunohistochemistry analyses validated the decreased HSP27 and increased milk fat globule epidermal growth factor-8 (MFG-E8) in SNX rats. Functional classification of differential protein profiles using KOGnitor revealed that the two major categories involved in aortic stiffness are posttranslational modification, protein turnover, chaperones (23%) and cytoskeleton (21%). Ingenuity Pathway Analysis highlighted cellular assembly and organization, and cardiovascular system development and function as the two most relevant pathways. Among the identified proteins, the clinical significance of the secreted protein MFG-E8 was confirmed in 50 CKD patients, showing that increased serum MFG-E8 level is positively related to aortic stiffness and renal function impairment. Drug interventions with an inhibitor of the angiotensin converting enzyme, enalapril, in SNX rats improved aortic stiffness and decreased MFG-E8 depositions. Together, our studies provide a repertoire of potential biomarkers related to the aortic stiffness in CKD.