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  • Phosphoinositide kinase PI K Akt

    2023-10-11

    Phosphoinositide 3-kinase (PI3K)/Akt has been well demonstrated in the protection of myocardial cell against IR injury via increasing cardiomyocyte survival, inhibiting excessive autophagy, et al. (Kong et al., 2016). The p2x7 receptor of ERK1/2 also involves in the regulation of cardiac myocyte survival during early reperfusion and serves as a defence mechanism against ischaemic stress stimuli (Yue et al., 2000). In accordance with previous reports (Zheng et al., 2011), we also observed that DRm217 enhanced Akt and ERK1/2 phosphorylation, suggesting that DRm217 activated myocardial PI3K/Akt and ERK1/2 signaling following IR. The increase of PI3K/Akt and ERK1/2 activity are not dependent on Src activation. Oppositely, Src activation was blocked by DRm217. These results reinforces previous reports that activation of the PI3K/Akt and MEK/ERK pathways via the Na+/K+-ATPase is independent of Src (Wu et al., 2013; Ono et al., 2016; Madan et al., 2017). Most importantly, administration with PI3K/Akt inhibitor LY294001 and ERK1/2 inhibitor PD98059 abolished the DRm217-induced attenuation of cardiac cell injury provoked by myocardial IR, suggesting that PI3K/Akt and ERK1/2 signaling also play roles in mediating the cardioprotection of DRm217 against IR injury. However, PI3K/Akt and ERK1/2 signaling have no effect on DRm217-related ROS depression in IR, suggesting another mechanism except Src/ROS also involved in the cardioprotection of DRm217. The downstream target of PI3K/Akt and ERK1/2 should be clarified in the next step. In conclusion, we demonstrated that DRm217 had protective effect against IR-related cardiac cell injury and apoptosis. The mechanism may be associated with the stabilizing Na+-K+-ATPase cell surface expression, inhibiting Na+-K+-ATPase/Src/NADPH oxidase/ROS pathway, and enhancing Akt and ERK1/2 phosphorylation.
    Conflict of interests
    Acknowledgements The project was supported by the National Natural Science Foundation of China (No. 81400232), China Postdoctoral Science Foundation (No. 2015M572572), the Natural Science Foundation of Shaanxi Province (No. 2016JM8021), and the Fundamental Research Funds for the Central Universities (XJTU2018).
    Introduction Riemerella anatipestifer (Ra) is a gram-negative member of the Flavobacteriaceae. This bacterium is the aetiological agent of infectious serositis disease, which causes major economic losses in the duck industry throughout the world [1]. More than 21 serotypes of R. anatipestifer have been reported, with variations in the common serotypes in different regions [2]. Inactivated bacterial vaccines have very poor protection against infection with heterologous strains [3]. Chemotherapy is an effective method in the treatment of ducks infected with R. anatipestifer [4], and the extensive use of antibiotics for the treatment and prevention has resulted in multi-drug resistance [[5], [6], [7], [8]]. The investigation of the pathogenic mechanisms and identification of the conserved antigens of R. anatipestifer are urgently needed. GroEL is present in almost all bacteria and is a classic representative heat shock protein (HSP). GroEL homologues are thought to be essential chaperones for bacterial growth in many bacteria [9]. The main function of GroEL is as a molecular chaperone in cells, aiding in the response to stress-induced cell damage by supporting denatured protein assembly and folding cooperativity in ATP hydrolysis. The high expression of GroEL can strengthen the resistance to environmental stresses to maintain normal metabolism and cell structural integrity [10,11]. Several serotypes of R. anatipestifer have been completely sequenced [[12], p2x7 receptor [13], [14], [15]], and our research group and others have conducted deep analyses of specific genes in this species [[16], [17], [18]]. The immunochemical properties of GroEL from R. anatipestifer (designated as RaGroEL) have been studied in detail. Using immunoproteomics, GroEL was shown to be a cross-immunogenic antigen among serotypes 1, 2 and 10 of R. anatipestifer [19]. However, the function of RaGroEL as a molecular chaperone is still unclear.