Down-regulation of SIK2 expression alleviates myocardial ischemia-reperfusion injury in rats by inhibiting autophagy through the mTOR-ULK1 signaling pathway / 南方医科大学学报

OBJECTIVE@#To explore the role of salt-inducible kinase 2 (SIK2) in myocardial ischemia-reperfusion (IR) injury in rats.@*METHODS@#Fifteen male SD rats were randomized equally into sham operation group, myocardial IR model group, and SIK2 inhibitor group (in which the rats were treated with intravenous injection of 10 mg/kg bosutinib via the left femoral vein 24 h before modeling). Ultrasound was used to detect the cardiac function of the rats, and myocardial pathologies were observed with HE staining. Transmission electron microscopy was used to observe autophagy of myocardial cells, and Western blotting was performed to detect the contents of the autophagy-related proteins SIK2, LC3B, Beclin-1, p62 and the expressions of p-mTOR, mTOR, p-ULK1, and ULK1 in myocardial tissue.@*RESULTS@#Myocardial IR injury significantly increased the number of autophagosomes (P < 0.05) and the expression of SIK2 protein (P < 0.01) in the myocardial tissues. Treatment with bosutinib before modeling obviously lowered the expression of SIK2 protein (P < 0.01), alleviated myocardial pathologies, and reduced the number of autophagosomes (P < 0.05) in the myocardial tissue. The rats with myocardial IR injury showed obviously lowered LVEF and FS values (P < 0.001), which were significantly improved by bosutinib treatment (P < 0.05); no significant difference was detected in IVSDd or LVPWDd among the 3 groups (P > 0.05). Myocardial IR injury obviously increased the expressions of LC3-II/LC3-I and Beclin-1 proteins and lowered the expression of p62 protein (P < 0.01), and these changes were significantly rescued by bosutinib treatment (P < 0.05). The rat models of myocardial IR injury showed significantly increased expression of p-ULK1 (Ser757) (P < 0.01) and lowered expression of p-mTOR protein (P < 0.0001) in the myocardium, and these changes were obviously reversed by bosutinib (P < 0.01 or 0.05); there was no significant difference in mTOR and ULK1 expressions among the 3 groups (P > 0.05).@*CONCLUSION@#SIK2 may promote autophagy through the mTOR/ULK1 signaling pathway, and inhibiting SIK2 can reduce abnormal autophagy and alleviate myocardial IR injury in rats.

Transcription factors EB and Parkinson's disease / 中国药理学通报

Autophagy is a powerful process for removing such proteins and for maintaining homeostasis.However,autophagy dysfunction has also been implicated in the pathogenesis of vari-ous neurodegenerative diseases,including Parkinson 's disease (PD).Recent studies have shown that TFEB could regulate au-tophagy and lysosome function through regulating the expressionof the relatedgenes.Thus,TFEB plays a key role in the occur-rence of Parkinson's disease.Therefore,this article will make a review of the regulatory mechanism of TFEB and its role in Par-kinson's disease.