Abstract
We hypothesized that a functional apolipoprotein LI (APOL1)-miR193a axis (inverse relationship) preserves, but disruption alters, the podocyte molecular phenotype through the modulation of autophagy flux. Podocyte-expressing APOL1G0 (G0-podocytes) showed downregulation but podocyteexpressing APOL1G1 (G1-podocytes) and APOL1G2 (G2-podocytes) displayed enhanced miR193a expression. G0-, G1-, and G2- podocytes showed enhanced expression of light chain (LC) 3-II and beclin-1, but a disparate expression of p62 (low in wild-type but high in risk alleles). G0-podocytes showed enhanced, whereas G1- and G2-podocytes displayed decreased, phosphorylation of Unc-51-like autophagy-activating kinase (ULK)1 and class III phosphatidylinositol 3-kinase (PI3KC3). Podocytes overexpressing miR193a (miR193a-podocytes), G1, and G2 showed decreased transcription of PIK3R3 (PI3KC3=s regulatory unit). Since 3-methyladenine (3-MA) enhanced miR193a expression but inhibited PIK3R3 transcription, it appears that 3-MA inhibits autophagy and induces podocyte dedifferentiation via miR193a generation. miR193a-, G1-, and G2-podocytes also showed decreased phosphorylation of mammalian target of rapamycin (mTOR) that could repress lysosome reformation. G1- and G2-podocytes showed enhanced expression of run domain beclin-1- interacting and cysteine-rich domain-containing protein (Rubicon); however, its silencing prevented their dedifferentiation. Docking, protein-protein interaction, and immunoprecipitation studies with antiautophagy- related gene (ATG)14L, anti-UV radiation resistance associated gene (UVRAG), or Rubicon antibodies suggested the formation of ATG14L complex I and UVRAG complex II in G0-podocytes and the formation of Rubicon complex III in G1- and G2-podocytes. These findings suggest that the APOL1 risk alleles favor podocyte dedifferentiation through blockade of multiple autophagy pathways.
Original language | English |
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Pages (from-to) | C209-C225 |
Journal | American Journal of Physiology - Cell Physiology |
Volume | 317 |
Issue number | 2 |
DOIs | |
State | Published - 1 Aug 2019 |
Externally published | Yes |
Bibliographical note
Publisher Copyright:© 2019 the American Physiological Society.
Funding
This work was supported by National Institute of Diabetes and Digestive and Kidney Diseases Grants RO1 DK-098074 and RO1 DK-118017 to P. C. Singhal and by grants to K. Skorecki from the Israel Science Foundation (ISF 182/15) and Rambam Medical Center, Kaylie Kidney Health Center of Excellence, and the Beutler Foundation for Genomic Medicine Research.
Funders | Funder number |
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Beutler Foundation | |
National Institute of Diabetes and Digestive and Kidney Diseases | R01DK118017, RO1 DK-098074 |
Israel Science Foundation | ISF 182/15 |
Keywords
- APOL1
- Autophagy
- Dedifferentiation of podocytes
- MiR193a
- Podocytes