Abstract: FR-PO065
Significance of Pax2 Reactivation After Kidney Injury
Session Information
- AKI: Tubules, Metabolism, New Models
October 26, 2018 | Location: Exhibit Hall, San Diego Convention Center
Abstract Time: 10:00 AM - 12:00 PM
Category: Acute Kidney Injury
- 103 AKI: Mechanisms
Authors
- Sako, Keisuke, Kanazawa University, Kanazawa, Japan
- Makiishi, Shohei, Kanazawa University, Kanazawa, Japan
- Yamamura, Yuta, Kanazawa University, Kanazawa, Japan
- Iwata, Yasunori, Kanazawa University, Kanazawa, Japan
- Sakai, Norihiko, Kanazawa University, Kanazawa, Japan
- Shimizu, Miho, Kanazawa University, Kanazawa, Japan
- Furuichi, Kengo, Kanazawa University, Kanazawa, Japan
- Wada, Takashi, Kanazawa University, Kanazawa, Japan
Background
Pax2 is a transcription factor necessary for kidney development. It has been reported that homozygous mutation of Pax2 is embryonic lethal. On the other hand, Pax2 expression in the mature kidney is almost diminished. However, it has been reported that Pax2 is reactivated in the proximal epithelial tubular cells at the recovery phase of the injury. It has also been reported that Pax2 is involved in stimulation of cell proliferation. In this study, we examined the effect of reactivating Pax2 on kidney injury.
Methods
To determine the function of Pax2 reactivation in mouse proximal tubules of kidneys, we generated kidneyproximal tubule-specific Pax2 conditional knockout (K/O) mice. We generated a transgenic mouse that expresses Cre recombinase under the control of the promoter of the kidney androgen-regulated protein (KAP) gene (Pax2 flox/flox; KAP-Cre+male mouse). Kidney ischemia was induced in male mice of 6-week-old C57BL/6J (B6) male mice and conditional K/O mice. The left renal artery and vein of these mice were clamped for 60 min to induce ischemia -reperfusion (I/R) injury. Kidney tissues were removed for examination 2, 4, 7 or 14 days after I/R. We evaluated cell proliferation (immunohistochemical staining of Ki-67 and BrdU), inflammation (immunohistochemical staining of F4/80 and CD3) and fibrosis (sirius red staining and hydroxyproline assay). We also conducted similar experiments on Pax2 hetero K/O mice and Pax2 siRNA induction mice.
Results
In B6 male mice, the number of Pax2 positive cells and mRNA expressions increased after I/R. Immunohistochemical analysis of CD3 and F4/80 showed at increasing number of the in inflammatory cell infiltration in conditional K/O mice (p<0.05). In analysis of interstitial fibrosis, the area ratio of sirius red staining and the hydroxyproline assay were higher in conditional K/O mice at day 14 after I/R (p<0.05). The number of Ki-67 positive cells was decreased in conditional knockout mice at day 2 after I/R (p<0.01). Almost of all the Ki 67-positive cells were co-positive with BrdU.
In addition, the area ratio of sirius red staining was also higher in Pax2 hetero K/O mice and Pax2 siRNA induction mice at 14 days after I/R (p<0.05).
Conclusion
Reactivation of Pax2 after ischemia reperfusion injury may be involved in cell proliferation and interstitial fibrosis suppression in the injured kidney.