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Reductionin RNF125-mediated RIG-I ubiquitination and degradation promotes renal inflammation and fibrosis progression

LI Lu-Xin¹, JI Ting-Ting¹, LU Li², LI Xiao-Ying¹, LU Li-Min², BAI Shou-Jun^1,*

¹Department of Nephrology, Qingpu Branch of Zhongshan Hospital Affiliated to Fudan University, Shanghai 201700, China；²Department of Physiology and Pathophysiology, School of Basic Medical Sciences, Fudan University, Shanghai 200032, China

Abstract

Persistent inflammation plays a pivotal role in the initiation and progression of renal fibrosis. Activation of the pattern recognition receptor retinoic acid-inducible gene-I (RIG-I) is implicated in the initiation of inflammation. This study aimed to investigate the upstream mechanisms that regulates the activation of RIG-I and its downstream signaling pathway. Eight-week-old male C57BL/6 mice were used to establish unilateral ureteral obstruction (UUO)-induced renal fibrosis model, and the renal tissue samples were collected 14 days later for analysis. Transforming growth factor-β (TGF-β)-treated mouse renal tubular epithelial cells were used in in vitro studies. The results demonstrated that, compared to the control group, UUO kidney exhibited significant fibrosis, which was accompanied by the increases of RIG-I, p-NF-κB p65 and inflammatory cytokines, such as TNF-α and IL-1β. Additionally, the protein level of the E3 ubiquitin ligase RNF125 was significantly downregulated and predominantly localized in the renal tubular epithelial cells. Similarly, the treatment of tubular cells with TGF-β induced the increases in RIG-I, p-NF-κB p65 and inflammatory cytokines while decreasing RNF125. Co-immunoprecipitation (Co-IP) assays confirmed that RNF125 was able to interact with RIG-I. Overexpression of RNF125 promoted the ubiquitination of RIG-I, and accelerated its degradation via the ubiquitin-proteasome path way. Overexpression of RNF125 in UUO kidneys and in vitro tubular cells effectively mitigated the inflammatory response and renal fibrosis. In summary, our results demonstrated that the decrease in RNF125 under pathological conditions led to reduction in RIG-I ubiquitination and degradation, activation of the downstream NF-κB signaling pathway and increase in inflammatory cytokine production, which promoted the progression of renal fibrosis.

Key words: kidney fibrosis; inflammation; ubiquitination; RNF125; RIG-I

Received: 　　Accepted:

Corresponding author: 白寿军　　E-mail:

DOI: 10.13294/j.aps.2025.0028

Citing This Article：

LI Lu-Xin, JI Ting-Ting, LU Li, LI Xiao-Ying, LU Li-Min, BAI Shou-Jun. Reductionin RNF125-mediated RIG-I ubiquitination and degradation promotes renal inflammation and fibrosis progression. Acta Physiol Sin 2025; 77 (3): 385-394 (in Chinese with English abstract).