Isobaric tags for relative and absolute quantitation­based proteomics reveals potential novel biomarkers for the early diagnosis of acute myocardial infarction within 3 h.

Acute myocardial infarction (AMI) is one of the most common and life­threatening cardiovascular diseases. However, the ability to diagnose AMI within 3 h is currently lacking. The present study aimed to identify the differentially expressed proteins of AMI within 3 h and to investigate novel biomarkers using isobaric tags for relative and absolute quantitation (ITRAQ) technology. A total of 30 beagle dogs were used for establishing the MI models successfully by injecting thrombin powder and a polyethylene microsphere suspension. Serum samples were collected prior to (0 h) and following MI (1, 2 and 3 h). ITRAQ­coupled liquid chromatography­mass spectrometry (LC­MS) technology was used to identify the differentially expressed proteins. The bioinformatics analysis selected several key proteins in the initiation of MI. Further analysis was performed using STRING software. Finally, western blot analysis was used to evaluate the results obtained from ITRAQ. In total, 28 proteins were upregulated and 23 were downregulated in the 1 h/0 h group, 28 proteins were upregulated and 26 were downregulated in the 2 h/0 h group, and 24 proteins were upregulated and 19 were downregulated in the 3 h/0 h group. The Gene Ontology (GO) annotation and functional enrichment analysis identified 19 key proteins. Protein­protein interactions (PPIs) were investigated using the STRING database. GO enrichment analysis revealed that a number of key proteins, including ATP synthase F1 subunit ß (ATP5B), cytochrome c oxidase subunit 2 and cytochrome c, were components of the electron transport chain and were involved in energy metabolism. The western blot analysis demonstrated that the expression of ATP5B decreased significantly at all three time points (P<0.01), which was consistent with the ITRAQ results, whereas the expression of fibrinogen γ chain increased at 2 and 3 h (P<0.01) and the expression of integrator complex subunit 4 increased at all three time points (P<0.01), which differed from the ITRAQ results. According to the proteomics of the beagle dog MI model, ATP5B may serve as the potential biomarkers of AMI. Mitochondrial dysfunction and disruption of the electron transport chain may be critical indicators of early MI within 3 h. These finding may provide a novel direction for the diagnosis of AMI.

Inhibition of farnesyl pyrophosphate synthase attenuates angiotensin II-induced fibrotic responses in vascular smooth muscle cells.

Through the regulation of the RhoA/Rho kinase (ROCK) pathway, angiotensin II (Ang II)-induced fibrotic responses contribute to vascular remodeling. Farnesyl pyrophosphate synthase (FPPS) plays an important role in cardiovascular remodeling through the modulation of the above-mentioned pathway. However, the role of FPPS in Ang II-induced fibrotic responses and the related molecular mechanisms have not yet been elucidated. In the present study, vascular smooth muscle cells (VSMCs) from Sprague-Dawley (SD) rats were stimulated with Ang II. Cell proliferation was measusred usin the cell counting kit-8 (CCK-8). The levels of connective tissue growth factor (CTGF), FPPS, and those of phosphorylated and total extracellular signal-regulated kinase (ERK)1/2, p38 and c-Jun N-terminal kinase (JNK) were determined by western blot analysis. RhoA activity was determined using a pull-down assay. The results revealed that stimulation with Ang II enhanced cell proliferation, and increased the protein expression levels of FPPS and CTGF in the VSMCs. The inhibition of FPPS with ibandronate sodium attenuated the Ang II-induced increase in cell proliferation, CTGF expresison and RhoA activity; these effects were partially reversed by treatment with geranylgeraniol and were mimicked by GGTI-286. Furthermore, both SB203580 (a specific inhibitor of p38) and SP600125 (JNK1, JNK2 and JNK3 inhibitor) diminished the Ang II-induced production of CTGF; however, the inhibition of FPPS reduced the Ang II-induced activation of p38 mitogen-activated protein kinase (MAPK) and JNK. In conclusion, our data indicate that FPPS may play an important role in Ang II-induced fibrotic responses in VSMCs, and the underlying mechanisms at least partly involve the modulation of RhoA activity, and the p38 and JNK pathways.