Molecular interplay between TXNIP and GLUT9 underlies uric acid transport dysregulation in vitro under hyperuricemic stress.

Background: This study aimed to investigate the role of Thioredoxin Interacting Protein (TXNIP) in hyperuricemia, specifically examining its influence on uric acid (UA) metabolism and the associated processes.

Methods: A hyperuricemia cellular model was created using human renal tubular epithelial cells (HK-2). The DCFH-DA probe was utilized to quantify the quantities of reactive oxygen species (ROS) within cells. Cell lines exhibiting TXNIP overexpression and knockdown were established. The impact of TXNIP overexpression on UA metabolism in HK-2 cells was examined using integrated metabolomic and transcriptome analysis. Real-time fluorescence quantitative PCR (RT-qPCR) and Western blot were employed to assess the expression levels of TXNIP and the UA transporters GLUT9, ABCG2, URAT1, and OAT3. The connection between TXNIP and GLUT9 was investigated by the Co-immunoprecipitation. Additionally, immunofluorescence labeling was utilized to examine the subcellular localization of TXNIP and GLUT9.

Results: A high UA environment stimulated ROS generation and markedly elevated TXNIP expression. Research utilizing metabolomics and transcriptomics suggests that TXNIP may modify the UA metabolic pathway in HK-2 cells, hence affecting UA stability. Conversely, TXNIP overexpression enhanced net UA uptake in HK-2 cells by elevating GLUT9 expression, but TXNIP knockdown yielded the contrary effect. Immunofluorescence labeling demonstrated the co-localization of TXNIP and GLUT9 in HK-2 cells. CO-IP studies demonstrated that TXNIP interacted with GLUT9.

Conclusion: TXNIP may influence UA reabsorption in hyperuricemia via ROS-induced upregulation and subsequent enhancement of its expression through interaction with the UA transporter protein, GLUT9, hence impacting the progression of hyperuricemia.