Taxol prevents myocardial ischemia-reperfusion injury by inducing JNK-mediated HO-1 expression.
Parole chiave
Astratto
BACKGROUND
Ischemia/hypoxia and reperfusion impair mitochondria and produce a large amount of reactive oxygen species (ROS), which lead to mitochondrial and brain damage. Furthermore, heme oxygenase-1 (HO-1) as a cytoprotective gene protects cells against ROS-induced cell death in ischemia-reperfusion injury. Induction of HO-1 is involved in cytoprotective effects of taxol.
OBJECTIVE
We hypothesize that taxol protects cardiac myocytes possibly by preserving myocardial mitochondrial function and inducing HO-1 expression through the JNK pathway.
METHODS
In this project, the perfused Langendorff hearts isolated from rats were randomly divided into five groups: control, ischemic, ischemic + taxol (0.1 μM), ischemic + taxol (0.3 μM), and ischemic + taxol (1 μM). Briefly, following a 15 min equilibration period, the control group was subject to normoxic perfusion for 120 min; the ischemia group, normoxic reperfusion for 120 min after 30 min ischemia; the taxol groups, normoxic reperfusion for 120 min after 30-min ischemia with taxol (0.1, 0.3, or 1 μM). The microtubule disruption score, ROS levels, and the activity of mitochondrial electron transport chain complexes I and III were examined by using immunohistochemical methods and free radical detection kits. Western blot assay was employed to study the underlying mechanisms.
RESULTS
After Taxol treatment (0.1 µM), the ischemic microtubule disruption score was reduced to 9.8 ± 1.9%. The study revealed that 0.1, 0.3, and 1 μM taxol reduced the level of ROS by 33, 46 and 51%, respectively (p < 0.05). In additional, 0.3 and 1 μM taxol dramatically increased the activity of mitochondrial electron transport chain complex I (99.11 ± 2.59, 103.49 ± 3.89) and mitochondrial electron transport chain complex III (877.82 ± 12.08; 907.42 ± 16.21; 914.73 ± 19.39, *p < 0.05). Additionally, phosphorylation levels of JNK1 were significantly increased in the taxol group. Furthermore, the expression level of HO-1 increased with taxol treatments, which could be inhibited by the specific inhibitor of JNK, SP600125.
CONCLUSIONS
Taxol stabilized microtubules and effectively reduced ROS levels during ischemia. It also preserved the activity of mitochondrial complexes I and III. Interestingly, taxol induced the expression of HO-1 via the JNK pathway in cardiac myocytes.
