Abstract: PO1971
Podocyte Cell Cycle Activation During CKD Progression
Session Information
- Podocyte Biology
October 22, 2020 | Location: On-Demand
Abstract Time: 10:00 AM - 12:00 PM
Category: Glomerular Diseases
- 1204 Podocyte Biology
Authors
- Perin, Laura, Children's Hospital of Los Angeles, Los Angeles, California, United States
- Nicolas Frank, Camille H., Children's Hospital of Los Angeles, Los Angeles, California, United States
- De Filippo, Roger E., Children's Hospital of Los Angeles, Los Angeles, California, United States
- Lemley, Kevin V., Children's Hospital of Los Angeles, Los Angeles, California, United States
Background
Podocytes, quiescent cells, seem not capable of regeneration to compensate for their loss during CKD progression. Their only adaptive response to loss is through hypertrophy, allowing the remaining podocytes to effectively cover the filtration surface. This adaptive response is associated with signs of cell cycle activation, but podocytes do not divide successfully: they detach from the basal membrane and are lost in urine. How the cell cycle phases modulate this “mitotic catastrophe” is not known. To study the cell cycle in CKD, we used an Alport Syndrome (AS) mouse model characterized by podocyte loss, combined with the FUCCI technology which allow the identification of the cell cycle phases using fluorescent reporters: red for G1/S, green for S/G2/M, no color for G0.
Methods
We established a mouse model where FUCCI proteins are under the control of NPHS2 gene (podocytes specific) and crossed these mice with AS mice to generate AS-POD-FUCCI mice. Using flow cytometry, we isolated and evaluated podocyte number in different cell cycle phases in WT (male and female) and AS-POD-FUCCI mice (hemizygote males; heterozygote, Ht females) and perform proteomics in G1 and G0 podocytes. In vitro studies were performed in primary podocytes damaged with puromycin.
Results
In WT mice (males and females), as expected, 98.1% of podocytes were quiescent (G0). In AS mice, podocyte number in G0 decrease over time: at 2months (mild proteinuria) 89% are in G0, at 6months (end-stage kidney disease) 59% are in G0 while the percentage of podocytes in G1 increased from 7.6% at 2 months to 33% at 6 months. Podocytes also increased their cellular size (hypertrophy) along disease progression. In 6monts AS Ht females (mild proteinuria), only 15% of podocytes are in G1. PAN damage induced podocytes to switch from G0 to G1 phase, and rapamycin (a cell cycle regulator) rescue damage by maintaining cells in G0. Proteomics data showed important differences of cell cycle regulators (cyclins and CKDs, mTor, integrin signaling) between G0 and G1 of WT and AS mice.
Conclusion
We demonstrated that podocytes enter their cell cycle (in male and female) with an increase of cells in G1 (associated with proteinuria) as the disease worsens. Regulating cell cycle may be pivotal in developing novel therapies to prevent podocyte loss.
Funding
- Private Foundation Support