Abstract: SA-PO065
Tubular Cells Distant From the Site of Injury Enter the Cell Cycle and Undergo Polyploidization After AKI
Session Information
- AKI: Mechanisms - III
November 05, 2022 | Location: Exhibit Hall, Orange County Convention Center‚ West Building
Abstract Time: 10:00 AM - 12:00 PM
Category: Acute Kidney Injury
- 103 AKI: Mechanisms
Authors
- Lazzeri, Elena, Universita degli Studi di Firenze, Firenze, Toscana, Italy
- De Chiara, Letizia, Universita degli Studi di Firenze, Firenze, Toscana, Italy
- Romagnani, Paola, Universita degli Studi di Firenze, Firenze, Italy
Background
Acute Kidney Injury (AKI) is defined as a sudden decrease in kidney function affecting specifically the S3 segment of the proximal tubule in the outer medulla, despite a widespread cell cycle marker positivity observed all over the cortex. Importantly, we described the occurrence of polyploidization in tubular cells (TC) in response to AKI instead of proliferation. However, the spatial distribution of tubular cells undergoing polyploidy has never been investigated. Recently, an elegant genetic system has been established to unequivocally identify and trace polyploid cells in vivo, using the multicolored reporter Confetti. In this study, we aimed to 1. characterize the temporal distribution and 2. quantify and localize polyploid TC to different tubular segments after AKI.
Methods
To analyze the temporal distribution of polyploid TC, we employed Pax8/FUCCI2aR mice to combine cell cycle phases analysis with the DNA content by flow cytometry. To detect the spatial distribution of polyploid TC in all the tubular segments, we employed heterozygous-Pax8/Confetti mice in which one of the two sets of chromosomes harbors a Confetti allele.
Results
Ischemic AKI induced a strong entry into the cell cycle in TC. We found that in the early phase of AKI most cycling TC undergo polyploidization, while the others die during the S or G2/M phase of the cell cycle. To quantify as well as to localize polyploid TC to different tubular segments, we induced AKI in heterozygous-Pax8/Confetti mice. Polyploid TC carrying two or more sets of chromosomes can activate two or more fluorochromes, resulting in multi-colored TC. Multi-colored polyploid TC localized mostly in the cortex and especially in S1 and S2 segments of the proximal tubule, stained positive for cell cycle markers, sparing the injured outer medulla. This study demonstrated that in the early phase of AKI most cycling TC undergo polyploidization and this process occurred mostly distant from the site of injury.
Conclusion
We have characterized the temporal and spatial distribution of polyploid TC after AKI. Specifically: 1. most cycling TC undergo polyploidization, while most of the others die; 2. TC polyploidization occurs mostly in the cortex, distant from the injury site, explaining why AKI involves widespread cell cycle marker positivity all over the cortex.