Heat Shock Protein 70 Protects the Heart from Ischemia/Reperfusion Injury through Inhibition of p38 MAPK Signaling

Abstract

Background. Heat shock protein 70 (Hsp70) has been shown to exert cardioprotection. Intracellular calcium ([Ca2+]i) overload induced by p38 mitogen-activated protein kinase (p38 MAPK) activation contributes to cardiac ischemia/reperfusion (I/R) injury. However, whether Hsp70 interacts with p38 MAPK signaling is unclear. Therefore, this study investigated the regulation of p38 MAPK by Hsp70 in I/R-induced cardiac injury. Methods. Neonatal rat cardiomyocytes were subjected to oxygen-glucose deprivation for 6 h followed by 2 h reoxygenation (OGD/R), and rats underwent left anterior artery ligation for 30 min followed by 30 min of reperfusion. The p38 MAPK inhibitor (SB203580), Hsp70 inhibitor (Quercetin), and Hsp70 short hairpin RNA (shRNA) were used prior to OGD/R or I/R. Cell viability, lactate dehydrogenase (LDH) release, serum cardiac troponin I (cTnI), [Ca2+]i levels, cell apoptosis, myocardial infarct size, mRNA level of IL-1β and IL-6, and protein expression of Hsp70, phosphorylated p38 MAPK (p-p38 MAPK), sarcoplasmic/endoplasmic reticulum Ca2+-ATPase2 (SERCA2), phosphorylated signal transducer and activator of transcription3 (p-STAT3), and cleaved caspase3 were assessed. Results. Pretreatment with a p38 MAPK inhibitor, SB203580, significantly attenuated OGD/R-induced cell injury or I/R-induced myocardial injury, as evidenced by improved cell viability and lower LDH release, resulted in lower serum cTnI and myocardial infarct size, alleviation of [Ca2+]i overload and cell apoptosis, inhibition of IL-1β and IL-6, and modulation of protein expressions of p-p38 MAPK, SERCA2, p-STAT3, and cleaved-caspase3. Knockdown of Hsp70 by shRNA exacerbated OGD/R-induced cell injury, which was effectively abolished by SB203580. Moreover, inhibition of Hsp70 by quercetin enhanced I/R-induced myocardial injury, while SB203580 pretreatment reversed the harmful effects caused by quercetin. Conclusions. Inhibition of Hsp70 aggravates [Ca2+]i overload, inflammation, and apoptosis through regulating p38 MAPK signaling during cardiac I/R injury, which may help provide novel insight into cardioprotective strategies.

Dexmedetomidine Attenuates Ischemia/Reperfusion-Induced Myocardial Inflammation and Apoptosis Through Inhibiting Endoplasmic Reticulum Stress Signaling

“…The rat myocardial I/R injury model was established as previously described. 22 , 24 Rats were anesthetized with intraperitoneal sodium pentobarbital 50 mg/kg. After tracheal intubation, the lungs were ventilated with room air, tidal volume 20 mL/kg, 1:1 ratio, and 70 breaths/min, by using an animal ventilator (R407, RWD, Shenzhen, China).…”

“…H9c2 cardiomyocytes were treated with glucose-free DMEM and incubated in a hypoxia chamber with 95% N 2 and 5% CO 2 at 37 °C, as previously described. 23 , 24 The cells were subjected to OGD for 12 h, followed by reoxygenation for 3 h with the normal DMEM under a normoxia condition.…”

Heat Shock Proteins in Oxidative Stress and Ischemia/Reperfusion Injury and Benefits from Physical Exercises: A Review to the Current Knowledge

“…Song et al indicated that rat cardiomyocytes subjected to oxygen-glucose deprivation/reperfusion showed increased expression of HSP70 and p-p38 MAPK; the same observation applies to increased HSP70 expression and phosphorylated p38 MAPK during I/R-induced myocardial injury, and inhibition of HSP70 by quercetin significantly increased myocardial infarct size [ 85 ]. It is very important that HSP70 inhibition led to upregulation of p-p38 MAPK and p-STAT3 and downregulation of SERCA2 (sarco/endoplasmic reticulum Ca 2+ -ATPase) during myocardial I/R injury, and inhibition of p38 MAPK phosphorylation attenuated effects induced by HSP70 inhibition [ 85 ]. In contrast to inhibition of HSP90, inhibition of HSP70 aggravates [Ca 2+ ] i overload, apoptosis, and inflammation through regulating p38 MAPK signaling during I/R cardiac injury.…”

p38 MAPK Pathway in the Heart: New Insights in Health and Disease

“…p38 inhibition during ischemia–reperfusion decreases mitochondrial swelling, protects against ultra-structure alterations, and mitigates mitochondrial membrane depolarization [ 78 ]. There is also evidence that p38 activation during ischemia–reperfusion contributes to cardiac damage by triggering intracellular Ca 2+ overload [ 79 ]. Pharmacological inhibition of p38 during ischemia–reperfusion induces cardioprotection by promoting phospholamban phosphorylation, increasing the activity of sarcoplasmic reticulum Ca 2+ -ATPase (SERCA2), and decreasing Ca 2+ overload [ 80 ].…”