Authors:H. Cross, M. Li, B. Petrich, E. Murphy, Y. Wang, and Charles Steenbergen
The p38 MAP kinases are stress-activated MAP kinases whose induction is often associated with the onset of heart failure. This study investigated the role of p38 MAP kinase isoforms in the regulation of myocardial contractility and ischemia/reperfusion injury using mice with cardiac-specific expression of kinase dead (dominant negative) mutants of p38α (p38αdn) or p38β (p38βdn). Hearts were subjected to 20 min ischemia and 40 min reperfusion. Immunofluorescence staining for p38αdn and p38βdn protein was performed on neonatal cardiomyocytes infected with adenovirus expressing flag-tagged p38αdn and p38βdn protein. Basal contractile function was increased in both p38αdn and p38βdn hearts compared to WT. Ischemic injury was increased in p38βdn vs. WT hearts, as indicated by lower posti-schemic recoveries of contractile function and ATP. However, despite a similar increase in contractility, ischemic injury was not increased in p38αdn vs. WT hearts. Immunohistological analysis of cardiomyocytes with comparable levels of protein overexpression show that p38αdn and p38βdn proteins were co-localized with sarcomeric α-actinin, however, p38αdn was detected in the nucleus while p38βdn was exclusively detected in the cytosol. In summary, attenuated p38 activity led to increased myocardial contractility; specific isoforms of p38 and their sub-cellular localization may have different roles in modulating ischemic injury.
Authors:J. Chen, L. Wang, W.H. Liu, J. Shi, Y. Zhong, S.J. Liu, and S.M. Liu
Although the use of aspirin has substantially reduced the risks of cardiovascular events and death, its potential mechanisms have not been fully elucidated. In a previous study, we found that aspirin triggers cellular autophagy. In the present study, we aimed to determine the protective effects of aspirin on human coronary artery endothelial cells (HCAECs) and explore its underlying mechanisms. HCAECs were treated with oxidized low-density lipoprotein (ox-LDL), angiotensin II (Ang-II), or high glucose (HG) with or without aspirin stimulation. The expression levels of endothelial nitric oxide (NO) synthase (eNOS), p-eNOS, LC3, p62, phosphor-nuclear factor kappa B (p-NF-κB), p-p38 mitogen-activated protein kinase (p-p38 MAPK), and Beclin-1 were detected via immunoblotting analysis. Concentrations of soluble intercellular adhesion molecule-1 (sICAM-1) and soluble vascular cell adhesion molecule-1 (sVCAM-1) were measured via ELISA. NO levels were determined using the Griess reagent. Autophagic flux was tracked by tandem mRFP-GFP-tagged LC3. Results showed that aspirin increased eNOS level and reduced injury to the endothelial cells (ECs) caused by ox-LDL, Ang-II, and HG treatment in a dose-dependent manner. Aspirin also increased the LC3II/LC3I ratio, decreased p62 expression, and enhanced autophagic flux (autophagosome and autolysosome puncta) in the HCAECs. p-NF-κB and p-p38 mitogen-activated protein kinase inhibition, sVCAM-1 and sICAM-1 secretion, and eNOS activity promotion by aspirin treatment were found to be dependent on Beclin-1. These results suggested that aspirin can protect ECs from ox-LDL-, Ang-II-, and HG-induced injury by activating autophagy in a Beclin-1-dependent manner.