Mechanism Of Lipin3 In Acute Kidney Injury

Background: Acute kidney injury(AKI)is a common critical illness caused by multiple causes of acute renal dysfunction in the short term.Nephrotoxic drugs,sepsis and ischemia-reperfusion injury can induce AKI.Because the cellular and molecular mechanisms of AKI have not been fully elucidated,there is still a lack of effective AKI diagnostic biomarkers and interventions.Therefore,it is of great scientific value and clinical significance to actively carry out research on the pathogenesis of AKI and find out potential diagnostic markers and candidate intervention targets for the prevention and treatment of AKI.Lipin3 is a member of the Lipin family,which is mainly involved in maintaining the balance of lipid metabolism.Lipin has two known biological functions.In the cytoplasm,Lipin is involved in lipid synthesis as a phospholipid phosphatase.In the nucleus,Lipin acts as a transcriptional co-stimulatory factor to regulate the expression of related genes.Among the studies related to Lipin,Lipin3 has been studied the least,so many of its functions are still unclear.Literatures have shown that Lipin3 is localized in both the nucleus and cytoplasm of cells and expressed in the kidney,liver,adipose tissue,and small intestine.However,there are no reports on the role of Lipin3 in AKI in domestic or foreign studies.Purpose: 1)The Lipin3 gene knockout mouse model is used to confirm the important role of Lipin3 in regulating pyroptosis of renal tubular epithelial cells in cisplatin-induced AKI;2)Investigate the molecular mechanism of Lipin3 regulating pyroptosis of renal tubular epithelial cells;3)Set up perfect clinical resource database of AKI patients,clarify the correlation between Lipin3 and AKI,and explore its clinical value in the diagnosis and prevention of AKI.Methods: We conducted bioinformatics analysis on public AKI datasets to explore the association between Lipin3 and AKI.We clinically collected blood samples from 54 AKI patients as well as some kidney biopsy specimens,and examined changes in Lipin3 expression via ELISA and immunohistochemistry.We used Lipin3 knockout mice and primary renal tubular cells and investigated the function and mechanism of Lipin3 in AKI by means of/via techniques such as WB,q PCR,immunohistochemistry,immunofluorescence,RNA-seq,flow cytometry,and Co-IP.Results: Bioinformatics analysis of the AKI public dataset showed that Lipin3 was upregulated in the AKI sample group and highly expressed in the damaged proximal tubular epithelial cells.Among 54 AKI patients,we found that the expression of Lipin3 was elevated in some AKI patients,and the level of Lipin3 expression was positively correlated with the degree of kidney injury in patients.In vivo experiments,cisplatin induced an increase in Lipin3 expression in renal tissue,and Lipin3 knockout increased the sensitivity of mice to cisplatin toxicity and exacerbated cisplatin-induced kidney injury,which was manifested by increased apoptosis of renal tissue cells,mitochondrial dysfunction,oxidative stress injury,and aggravated inflammatory response.In vitro experiments,we found that Lipin3 knockout primary renal tubular epithelial cells were more sensitive to cisplatin toxicity,which was manifested by decreased cell viability,exacerbated mitochondrial damage,and increased cell death.Subsequent studies found that Lipin3 knockout resulted in severe pyroptosis after cisplatin stimulation,increased LDH release,and significantly activated the Caspase-3-GSDME signaling pathway of pyroptosis.Further studies found that Lipin3 knockout led to upregulation of p21 transcription and translation,which was likely due to the decrease in the transcriptional activity of the p21 transcriptional suppressor Sirt1 caused by Lipin3 deficiency.This hypothesis was confirmed by a rescue experiment with overexpression of Sirt1.Conclusions: We investigated the mechanism of Lipin3 and its regulation of pyroptosis in cisplatin-induced AKI progression at multiple levels,including clinical trials,animal models,cell lines and molecules.We found that Lipin3 can regulate pyroptosis mediated by the Caspase-3-GSDME signaling pathway by binding to Sirt1 and affecting the expression of p21,and is involved in the progression of AKI.Our study suggested that Lipin3 and downstream molecules can serve as potential diagnostic markers and intervention targets for AKI.