ERK/PP1a/PLB/SERCA2a and JNK Pathways Are Involved in Luteolin-Mediated Protection of Rat Hearts and Cardiomyocytes following Ischemia/Reperfusion

Abstract

Luteolin has long been used in traditional Chinese medicine for treatment of various diseases. Recent studies have suggested that administration of luteolin yields cardioprotective effects during ischemia/reperfusion (I/R) in rats. However, the precise mechanisms of this action remain unclear. The aim of this study is to confirm that luteolin-mediated extracellular signal regulated kinase (ERK1/2) and c-Jun N-terminal kinase (JNK) pathways are responsible for their cardioprotective effects during I/R. Wistar rats were divided into the following groups: (i) DMSO group (DMSO); (ii) I/R group (I/R); (iii) luteolin+I/R group (Lut+I/R); (iv) ERK1/2 inhibitor PD98059+I/R group (PD+I/R); (v) PD98059+luteolin+I/R group (PD+Lut+I/R); and (vi) JNK inhibitor SP600125+I/R group (SP+I/R). The following properties were measured: contractile function of isolated heart and cardiomyocytes; infarct size; the release of lactate dehydrogenase (LDH); the percentage of apoptotic cells; the expression levels of Bcl-2 and Bax; and phosphorylation status of ERK1/2, JNK, type 1 protein phosphatase (PP1a), phospholamban (PLB) and sarcoplasmic reticulum Ca2+-ATPase (SERCA2a). Our data showed that pretreatment with luteolin or SP600125 significantly improved the contraction of the isolated heart and cardiomyocytes, reduced infarct size and LDH activity, decreased the rate of apoptosis and increased the Bcl-2/Bax ratio. However, pretreatment with PD98059 alone before I/R had no effect on the above indexes. Further, these consequences of luteolin pretreatment were abrogated by co-administration of PD98059. We also found that pretreatment with PD98059 caused a significant increase in JNK expression, and SP600125 could cause ERK1/2 activation during I/R. In addition, we are the first to demonstrate that luteolin affects PP1a expression, which results in the up-regulation of the PLB, thereby relieving its inhibition of SERCA2a. These results showed that luteolin improves cardiomyocyte contractile function after I/R injury by an ERK1/2-PP1a-PLB-SERCA2a-mediated mechanism independent of JNK signaling pathway.

Gypenoside attenuates renal ischemia/reperfusion injury in mice by inhibition of ERK signaling

“…MAPK compounds, including ERK, stress-activated protein kinases/c-Jun NH 2 -terminal kinases and p38 MAPKs have been implicated in inflammatory signaling mechanisms in I/R injury (30,31). Additionally, ERK signaling serves a crucial function in I/R-induced cell apoptosis (32,33). Ban et al (34) reported that the inhibition of ERK signaling worsened intestinal I/R injury.…”

Luteolin Enhances Sarcoplasmic Reticulum Ca2+-ATPase Activity through p38 MAPK Signaling thus Improving Rat Cardiac Function after Ischemia/Reperfusion

“…Single ventricular myocytes were obtained from the isolated rat hearts using type II collagenase (Gibco, Grand Island, NY, USA) as previously described [14, 23-25]. The cells were suspended 3 times with Krebs-bicarbonate solution (pH 7.2) containing (mM) 85 KCl, 15 NaCl, 5 MgSO 4 , 30 KH 2 PO 4 , 5 sodium pyruvate, 5 creatine, 20 taurine, 2 L-glutamic acid, 20 HEPES, 20 glucose, 0.2 CaCl2 and 0.5 EGTA, and was bubbled with 100% O 2 at 37°C.…”

“…Global I/R of the rat hearts was performed ex vivo according to our previous procedure [14]. Sodium heparin (1000 U/kg) and sodium pentobarbital (150 mg/kg) was administered to the experiment animals, then the rat hearts were excised and perfused, by Langendorff, with Krebs-Henseleit (KH) buffer solution containing (mM) 120 NaCl, 4.7 KCl, 1.2 KH 2 PO 4 , 1.2 MgSO 4 , 25 NaHCO 3 , 11 glucose and 1.25 CaCl 2, which was bubbled with 95% O 2 and 5% CO 2 at 37°C to maintain a pH of 7.4.…”

“…In our previous studies, we also found that the JNK and ERK1/2 pathways were important in regulating cardiomyocyte contractility and decreasing apoptosis. The ERK1/2-PP1a pathway regulates the expression of phosphorylated PLB and SERCA2a [14]. The p38 MAPK pathway is another important pathway of the MAPK family, and p38 MAPK pathway inhibition could alleviate cardiomyocyte I/R injury and develop cardio-protective effects [15, 16].…”

At the crossroads from bench to bedside: luteolin is a promising pharmacological agent against myocardial ischemia reperfusion injury

“…MicroRNAs (miRNAs) are noncoding RNA involved in the post-transcriptional regulation of protein expression, it has been demonstrated that miRNAs may contribute to classical IPC cardioprotection (40). According to the results of recent studies (1,(41)(42)(43), Lut is an interesting agent, it not only can play a role in multi-signalling pathway, but also can modulate miRNAs in the cardioprotection. The role of Lut in modulating miR-146b-5p and SECA2a/BAG1 against myocardial IRI is processing in our study.…”