#5403 PTEN-INDUCED KINASE 1 HAS ASSOCIATION WITH RENAL AGING PROCESS THROUGH THE CGAS -STING PATHWAY
Authors: Ha Min Heui , Kim Man S , An Hyun-Ju , Sung Min-Ji , Lee Yu Ho , Yang Dong Ho , Baek Jihyun , Choi Yueun , Lee So-Young , Jeong Hye Yun 
Published: June 2023

Abstract

Background and Aims
The global increase of an aging population has encouraged the research on renal aging, as the kidney is one of the organs that shows the greatest change as aging progresses. Although the mechanism of renal aging has not been clearly identified, dysfunctional mitochondria has been suggested as one of the factors that induce inflammation of the kidney, which is the major mediator of the pro-aging process of chronic kidney disease. PTEN-induced kinase 1(PINK1) is a protein involved in the quality control of mitochondria and regulates mitochondrial dysfunction. Although it is known that the mitochondrial DNA release promoted by PINK1 deficiency stimulates cyclic GMP–AMP synthase (cGAS) - stimulator of interferon genes (STING) pathway eventually resulting in the inflammatory response, the role of PINK1 and cGAS-STING pathway in renal aging has not yet been clarified. This study aimed to investigate the relationship between PINK1 and renal aging, especially through the cGAS-STING pathway.

Method
To determine the role of PINK1 on the renal aging process, renal fibrosis, and tubular injury were compared in 4- and 24-month-old wild-type (Pink1+/+) and PINK1 knockout (Pink1-/-) mice. To establish in vitro senescence model, hydrogen peroxide (H2O2) treatment on human renal proximal cells (HKC-8) was used. The changes in gene expression levels related to PINK1 were analyzed by RNA sequencing, applying transcriptomic and metabolomic analyses. To validate the results of RNA sequencing, we measured mitochondrial oxygen consumption rate (OCR) by Seahorse Mito Stress Test. To investigate the relationship between PINK1 and renal aging through the cGAS-STING pathway, we explored the change of cGAS-STING expression on senescence-induced HKC-8 cells and additionally used H-151 treatment, a specific STING inhibitor.

Results
The renal fibrosis and tubular injury were significantly aggravated in 24-month-old Pink1-/- mice compared to 24-month-old Pink1+/+ mice. Western blot and RT-qPCR confirmed remarkably increased senescence markers and senescence-associated secretory phenotype (SASPs) in 24-month Pink1-/- mice and senescence-induced HKC-8 cells. The RNA sequencing of mice kidneys showed that inflammation-related pathways significantly increased in 24 months Pink1-/-mice, and transcriptomic and metabolomic analyses showed that PINK1 has an association with mitochondrial metabolism dysregulation. On OCR measurement, the basal respiration, maximal respiration, ATP production, and respiratory capacity significantly declined in H2O2-treated siPINK1 cells, suggesting that PINK1 deficiency might have effects on mitochondrial dysfunction. Finally, the STING pathway was significantly activated in 24-month Pink1-/- mice and senescence-induced HKC-8 cells, which was inhibited by a specific inhibitor of STING, H-151.

Conclusion
In conclusion, PINK1 is associated with renal aging, and the dysregulation of mitochondria caused by PINK1 deficiency might lead to aging-related inflammatory responses through the cGAS-STING pathway.