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C-Jun NH2-terminal kinases (JNKs) are strongly activated by various cellular stresses. While autophagy can be induced to promote cell survival during the initial change of environmental conditions. However, excessive autophagy causes cell apoptosis or death. Sitagliptin as a new type of anti-hyperglycemic agents, has a broad cardiovascular protective effects. But there is few researches about the role of this drug on stem cells. We aim to explore whether sitagliptin protects MSCs from apoptosis during hypoxia and serum deprivation (H/SD). Furthermore, the mechanism of this action will be studied. Therefore, we hypothesized that sitagliptin could protect MSCs from H/SD through by suppressing JNK/C-Jun signalling pathway which mediated excessive autophagy.
MSCs were exposed to different concentrations sitagliptin (control, 0.001 µM, 0.01 µM, 0.1 µM, 1 µM and 10 µM) for 6 h in hypoxia and serum deprivation. For later studies, the cells were incubated with the JNK inhibitor SP600125 (10 mM) before the addition of sitagliptin (1 µM). Cell apoptosis was assessed using Annexin V-FITC/PI Kit. And cell autophagy was assessed by detecting acidic vesicular organelles using acridine orange staining, transmission electron microscopy. Beclin1, light chain 3, and the phosphorylation of JNK and C-jun was analyzed by Western blotting.
Stained with Annexin V/PI, we found sitagliptin (0.001µM-10µM) reduced apoptosis of rat MSCs cultured in H/SD condition. And sitagliptin suppressed the autophagic activity observed in MSCs exposed to H/SD as identified by Beclin 1, LC3-II expression, and autophagosome formation. However, this effect was obstructed by SP600125. Bcl-2 protein increased, while bax protein, decreased in sitagliptin treated cells as showed by Western blotting. Meanwhile, MSCs treated with sitagliptin decreased phosphorylation of JNK and C-jun. The trend was partially inhibited by SP600125.
Sitagliptin increases survival of MSCs in hypoxia and serum deprivation by suppressing JNK/C-Jun signalling pathway which mediated excessive autophagy. And this study provides a novel explanation for the protective effect of sitagliptin on MSCs.
Poster Sessions, Expo North
Monday, March 11, 2013, 9:45 a.m.-10:30 a.m.
Session Title: Acute Coronary Syndromes: Basic V
Abstract Category: 2. Acute Coronary Syndromes: Basic
Presentation Number: 1300-191
- 2013 American College of Cardiology Foundation