〔Abstract〕 To investigate the expression of triple motif protein 21 (TRIM21) at different time points in Cisplatin induced acute kidney injury (Cis-AKI) mouse model and its correlation with pathological score . Methods Acute kidney injury (AKI) model was induced by intraperitoneal injection of cisplatin (20 mg/kg) . Peripheral blood serum was collected at 12 , 24 , 48 and 72 h , respectively . Body weight and kidney mass were also recorded . The dynamic changes of serum creatinine ( SCr) and urea nitrogen ( BUN) were detected . The expressions of TRIM21 Protein and endoplasmic reticulum stress (ERS) proteins GRP78 , GRP94 , P-elf2αand CHOP were de- tected by Western Blot. HE staining was used to observe the pathology of renal tissue and analyze the correlation between the expression of TRIM21 protein at different time points . Results Compared with the control group , the renal body ratio of Cis-AKI mice significantly increased at 48 h and 72 h (P < 0. 01) . SCr and BUN of Cis-AKI mice significantly increased at 48 h and 72 h compared with control group ( P < 0. 01) . HE staining showed that compared with the control group , the renal pathological scores of Cis-AKI mice increased at 12 and 24 h ( P < 0. 000 1) . At the same time , the expression of TRIM21 protein significantly increased at 24 h (P < 0. 01) . Com- pared with the control group , the renal pathological score of Cis-AKI mice significantly increased at 48 h ( P < 0. 000 1) , and the protein expression of TRIM21 , CHOP and GRP78 was significantly up-regulated at 48 h (P < 0. 05) . Compared with the control group , the renal pathological score of Cis-AKI mice significantly increased at 72 h (P < 0. 000 1) , and the expression of TRIM21 , GRP94 and P-elf2αproteins was significantly up-regulated at 72 h (P < 0. 05) . The results of correlation analysis showed that the expression of TRIM21 protein at different time points was positively correlated with the HE pathological scores at different time points (P < 0. 000 1) . Conclusion At different time points , TRIM21 may participate in the pathological progression of Cis-AKI by affecting ERS , and it is positively correlated with renal pathological scores , which is expected to become a potential early diagnos- tic marker and intervention target.