ASN's Mission

ASN leads the fight to prevent, treat, and cure kidney diseases throughout the world by educating health professionals and scientists, advancing research and innovation, communicating new knowledge, and advocating for the highest quality care for patients.

learn more

Contact ASN

1401 H St, NW, Ste 900, Washington, DC 20005

email@asn-online.org

202-640-4660

The Latest on Twitter

Kidney Week

Abstract: SA-PO730

Loss of Asparaginyl Endopeptidase Accelerates Cellular Senescence and Boosts Age-Related Renal Interstitial Fibrosis

Session Information

  • Geriatric Nephrology
    October 27, 2018 | Location: Exhibit Hall, San Diego Convention Center
    Abstract Time: 10:00 AM - 12:00 PM

Category: Geriatric Nephrology

  • 1100 Geriatric Nephrology

Authors

  • Tan, Xiaoyue, the School of Medicine, NanKai university, Tianjin, China
  • Wang, Dekun, the School of Medicine, NanKai university, Tianjin, China
  • Chen, Chuanai, the School of Medicine, NanKai university, Tianjin, China
  • Kang, Lichun, the School of Medicine, NanKai university, Tianjin, China
Background

Asparaginyl endopeptidase (AEP) is highly expressed in the renal tubuli while significantly declined in the elderly ones. AEP exhibits anti-fibrotic effect in the mouse model of unilateral ureteral obstruction. The role of AEP in the age-related fibrosis is obscure.

Methods

We compared the level of renal interstitial fibrosis and renal tubular senescence in the wild-type (wt) and AEP knockout (AEP-/-) mice at different ages. We established stable AEP-knockdown HK2 cell line (HK2-shAEP) and analyzed the cellular senescence. Then, we co-cultured HK2-shAEP with fibroblasts and assessed the activated indexes of fibroblasts. We also evaluated the lysosomal pH and change of autophagy upon AEP downregulation.

Results

Renal tubular senescence was obvious from the 3rd months in AEP-/- mice with significant accumulation of Fibronectin and Collagen I/III in the renal interstitial area. Levels of serum creatinine and urea nitrogen were 2 times higher than that in wt mice at the 6th months.
In vitro, AEP knockdown induced the cell cycle arrested at G1/S with increased expression of β-Gal, p21cip1 and p16ink4a. HK2-shAEP cells expressed and secreted more pro-fibrotic cytokines, including TGF-β1, CTGF and PAI-1. Co-culture with HK2-shAEP promoted the differentiation, migration and proliferation of fibroblasts. Blocking the senescent signaling via downregulating p21cip1 or p16ink4a could reverse the accelerated senescence and pro-fibrotic effects of HK2-shAEP cells.
Assessment of autophagy and lysosomal PH showed that knockdown of AEP led to impaired autophagy flux and disturbance of lysosomal homeostasis, accompanying with accumulation of ROS.
Autophagy inducer rapamycin or anti-senescence agent spermidine could reverse the senescent state of HK2-shAEP cells. in vivo, both spermidine and genetical mutant of p53 alleviated renal interstitial fibrosis of AEP-/- mice.

Conclusion

The study defines the role of AEP in regulation of autophagy via maintainance of lysosomal hemostasis in renal tubuli. Loss of AEP accelerates tubular senescence and boosts aged-related interstitial fibrosis. Therefore, our finding highlights AEP as a potential biomarker of age-related kidney diseases and therapeutic target.

Funding

  • Government Support - Non-U.S.