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Rap1 exacerbates myocardial ischemia/reperfusion injury through activation of NFκB signaling pathway and NLRP3 inflammasome
Author(s) -
Cai Yin,
Xie Xiang,
Pan Qixian,
Zhi Qiqi,
Woolford Michael G.,
Xia Zhengyuan
Publication year - 2020
Publication title -
the faseb journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.709
H-Index - 277
eISSN - 1530-6860
pISSN - 0892-6638
DOI - 10.1096/fasebj.2020.34.s1.03220
Subject(s) - rap1 , inflammasome , nf κb , medicine , iκbα , inflammation , tumor necrosis factor alpha , chemistry , signal transduction , biochemistry
Background Ischemic heart disease is a leading cause of morbidity and mortality worldwide. Activation of nuclear factor kappa B (NFκB)‐mediated inflammation has been demonstrated in various models of experimental myocardial ischemia/reperfusion injury (I/RI). Repressor activator protein 1 (Rap1), an established telomere‐associated protein, is a novel modulator of NFκB‐mediated inflammatory response. However, it is unknown whether Rap1 modulates NFκB signaling in cardiomyocytes to contribute to myocardial I/RI. Therefore, the present study aimed to explore the potential pro‐inflammatory role of Rap1 in myocardial I/RI and to determine the underlying molecular mechanism. Methods and Results In a mouse model of myocardial I/RI (30 minutes of left descending coronary artery ligation followed by 24 hours reperfusion), Rap1 deficiency significantly reduced myocardial infarct size and improved cardiac systolic/diastolic function (all p < 0.05, Rap1 −/− I/R vs. Rap1 +/+ I/R). This was associated with a reduction in NFκB activity [reduced phosphorylation, degradation of IκBα and phosphorylation of p65] and suppressed production of NFκB‐mediated pro‐inflammatory cytokines, including tumor necrosis factor α (TNFα), interleukin (IL)6 and IL1β in the post‐ischemic myocardium (all p < 0.05, Rap1 −/− I/R vs. Rap1 +/+ I/R). In cultured cardiac origin H9C2 cardiomyocytes, Rap1 knockdown did not significantly influence the pro‐inflammatory response in hypoxia/reoxygenation or in lipopolysaccharide‐stimulated H9C2 cells, but deletion of Rap1 significantly attenuated macrophage infiltration into the post‐ischemic myocardium of mice (p < 0.05, Rap1 −/− I/R vs. Rap1 +/+ I/R). Also, knockdown of Rap1 significantly suppressed NLRP3 inflammasome formation in THP‐1 macrophages in response to LPS and ATP (p < 0.05, Rap1 KD vs. Rap1 WT ). When post‐hypoxic H9C2 cardiomyocytes were co‐cultured with mock‐ or Rap1‐siRNA transfected THP‐1 macrophages, knockdown of Rap1 in macrophages significantly attenuated macrophage‐mediated/exacerbated cardiomyocyte injury (p < 0.05, Rap1 KD vs. Rap1 WT ). Conclusions These data collectively suggest that Rap1 may exacerbate myocardial I/RI through enhancing activation of NFκB signaling pathway and NLRP3 inflammasome formation, which may yield a novel therapeutic target for myocardial I/RI. Support or Funding Information The work was supported by the National Natural Science Foundation of China (No. 81800245) and General Research Fund (17117217M, 17123718M Research Grants Council of Hong Kong).