Abstract 268: Through the Inhibition of Autophagy Flux miR-221 Plays an Important Role in the Reductions of Hypoxia Reoxygenation Induced Cell Death and Collagen Synthesis in Cardiac Fibroblast
| Autor: | Arthur Mark Richards, Yue Zhou, Peipei Wang |
|---|---|
| Rok vydání: | 2018 |
| Předmět: |
Cardioprotection
Programmed cell death Physiology Chemistry Autophagy 030204 cardiovascular system & hematology Hypoxia (medical) medicine.disease Cell biology 03 medical and health sciences 0302 clinical medicine Apoptosis Fibrosis medicine Myocyte 030212 general & internal medicine medicine.symptom Cardiology and Cardiovascular Medicine Flux (metabolism) |
| Zdroj: | Circulation Research. 123 |
| ISSN: | 1524-4571 0009-7330 |
| Popis: | Purpose: We have previously reported that miR-221 protects myocytes against H/R-induced injury through the inhibitions of autophagy and apoptosis. It is not known has similar anti-autophagic and anti-apoptotic effects on cardiac fibroblast (cFB) and what role it plays in the regulation of cFB function. Method: Adult rat cFBs were isolated and transfected with miR-221 mimics and mimic control (miR-221 and MC). cFBs were subjected to normoxia (Nor) and H/R conditions. MiR-221 effects were monitored for cell injury (CCK8 and lactate dehydrogenase, LDH), apoptosis (Annexin V and 7-AAD staining), autophagy (LC3 and p62 by Western blot, WB) and collagen synthesis (Sircol). To study autophagy flux, Bafilomycin A1 (Baf) or Rapamycin (Rap) was applied to further inhibit or enhance autophagosome (ATGsome) formation and degradation respectively. Results: miRNA-221 increased cFB viability as indicated by increased CCK8 and reduced LDH release (miR-221 vs. MC) in H/R. This pro-survival effect did not involve apoptosis but reducing autophagy as indicated by unchanged Annexin V staining and reduced LC3-II/I ratio and increased p62 respectively. The protection was blocked by Rap. DMSO, the solvent used for the preparation of Baf and Rap, showed a significant induction of ATGsome formation on its own and override the anti-ATGsome formation effect of miR-221. In the presence of DMSO, miR-221 caused LC3 II accumulation, similar to the effect of Baf. In addition, miR-221 inhibited collagen synthesis as assessed by Sircol measurement. TGF-β, as a positive control, increased collagen synthesis significantly. The regulation of collagen synthesis of miR-221 and TGF-β could be abrogated by Rap and Baf respectively. Under Nor and H/R, the expressions of DDIT4 and Tp53inp1 were significantly downregulated by miR-221. Conclusion: Targeting on DDIT4 and Tp53inp1, miR-221 inhibited autophagy flux by reducing both ATGsome formation and degradation. The inhibition plays an important role in the protection of cFB and regulation of collage synthesis. This study reveals the complexity of cFB functional regulation by miRNA-221, preserving cFB in number without causing additional fibrosis. The unique feature of miR-221 might be an advantage in the treatment of cardiac infarction. |
| Databáze: | OpenAIRE |
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