Tripartite Motif Containing 37 (TRIM37 )-Mediated Ubiquitination of Forkhead Box Transcription Factor O1 (FOXO1) Elevates Lipopolysaccharide-Induced Ferroptosis in Lung Endothelial Cells

Background: Acute lung injury (ALI) is involved in reactive oxygen species (ROS)-induced ferroptosis. Purpose: The aim of the study was to explore the participation of ferroptosis and the mediation of forkhead transcription factor O1 (FOXO1) ubiquitination through tripartite motif containing 37 (TRIM37) in lipopolysaccharide (LPS)-induced ALI. Methods: Murine lung endothelial cells (MLECs) were isolated from mouse lungs and treated by LPS. The empty and experimen-tal vectors were transfected into MLECs by lipofection. 3-(4,5-Dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT), C11-BODIPY, and ROS generation assays were used to evaluate cell viability, lipid peroxidation, and ROS level. UbiBrowser was used to predict the potential ubiquitin ligases targeting FOXO1. Immunoprecipitation (IP) and Co-IP assays were used to confirm the connection between TRIM37 and FOXO1. Quantitative real-time polymerase chain reaction (qRT-PCR) and West-ern blot were utilized to calculate the messenger RNA (mRNA) and protein expressions of examined genes in MLECs. Results: In LPS-induced MLECs, TRIM37 expression was significantly high. Meanwhile, LPS significantly increased lipid per -oxidation and ROS, but significantly decreased cell viability as well as expressions of FOXO1 and ferroptosis-related proteins (solute carrier family 7 member 11 (SLC7A11) and glutathione peroxidase 4 (GPX4)) in MLECs. These changes were signifi-cantly reversed by FOXO1 overexpression. TRIM37 was predicted as a high-confidence ubiquitin ligase of FOXO1. TRIM37 and FOXO1 could bind with each other and TRIM37 degraded FOXO1 through ubiquitination in MLECs. TRIM37 overexpression significantly inhibited FOXO1 level and enhanced the effect of LPS on MLECs, which was reversed by overexpressing FOXO1. Conclusions: TRIM37-mediated ubiquitination of FOXO1 significantly elevates LPS-induced ferroptosis in lung endothelial cells.

Automated summary

This study found that in lipopolysaccharide (LPS)-induced acute lung injury, the ubiquitination mediated by tripartite motif containing 37 (TRIM37) regulated the involvement of forkhead transcription factor O1 (FOXO1) and degradation of proteins.