Abstract: FR-PO909
Anti-Apoptotic Role of Phosphatidylinositol-3 Kinase (PI3-Kinase) in Angiotensin II-Induced Podocyte Injury
Session Information
- Glomerular Diseases: Podocyte Biology - II
November 08, 2019 | Location: Exhibit Hall, Walter E. Washington Convention Center
Abstract Time: 10:00 AM - 12:00 PM
Category: Glomerular Diseases
- 1204 Podocyte Biology
Author
- Ha, Tae-Sun, Chungbuk National University College of Medicine, Cheongju-si, Korea (the Republic of)
Background
PI3-kinase has distinct roles in cellular processes spanning from metabolism to cell motility and survival. Angiotensin II (Ang II) promotes the development and progression of proteinuria and renal diseases and induces podocyte apoptosis. Phosphatidylinositol-3 kinase (PI3-K), connected to CD2-associated protein (CD2AP) in podocytes, is known to send signaling through nephrin-CD2AP-PI3-kinase/Akt pathway and promote cell survival. Autophagy and apoptosis constitute the two processes through which injured/aged cells or organelles are eliminated. We investigated the role of PI3-kinase in angiotensin II-induced podocyte injury.
Methods
Mouse podocytes were incubated in media containing various concentrations of Ang II and at different incubation times. Cell survival/death-modifying reagents and siRNA targeting SHIP2, a negative regulator of the PI3-kinase/Akt signaling pathway, and Atg5 were applied. The changes of podocyte autophagy and apoptosis were observed by confocal imaging, western blotting, realtime PCR, FACS and TUNEL assay according to the presence of Ang II.
Results
Ang II-treated podocytes showed an increase in autophagosomes compared with control cells at early phase in a dose-dependent manner. This pro-autophagic effect of Ang II was inhibited by pretreatment with 3-methyladenine (3-MA), an inhibitor of PI3-kinase class III. Atg5 siRNA reduced LC3 puncta levels and increased the number of apoptotic podocytes over that observed with Ang II treatment at 12 hours. Thereafter, Ang II reduced the expression of autophagy-related genes, such as, Atg3, Atg5, Atg7, and bcl-2 at 24 hours and induced podocyte apoptosis at later stages, 12 and 24 hours in concentration- and time-dependent manners in FACS and TUNEL assays. Thereafter, Ang II induced podocyte apoptosis significantly in concentration- and time-dependent manners in FACS and TUNEL assays. PI3-kinase inhibitors, 3-MA and LY294002, and Atg5 siRNA further increased Ang II-induced podocyte apoptosis. On the other hand, SHIP2 siRNA suppressed Ang II-induced podocyte apoptosis and the expression of apoptotic proteins. Therefore, PI3-kinase protect podocyte from apoptosis in angiotensin II-induced podocyte injury.
Conclusion
Our findings suggest that Ang II induces podocyte apoptosis, which could be prevented by PI3-kinase activation through the inhibition of SHIP2 and promoting autophagy.
Funding
- Government Support - Non-U.S.