Role of Hexokinase 2-Mediated Enolase 1 Translocation in Podocyte Injury

Background: Lupus nephritis (LN) is one of the most common and serious complications of systemic lupus erythematosus. Podocyte injury is associated with proteinuria and renal impairment in LN, and podocyte is dependent on glycolysis. However, the relationship between glycolysis and LN remains unclear. Hexokinase 2 (HK2) and enolase 1 (ENO1) are the glycolytic enzymes in cytoplasm. In physiological conditions, different glycolytic enzymes can form complexes, which contribute to their intracellular localization. In pathological conditions, the intracellular localization of glycolytic enzymes would be altered. Notably, cell membrane-localized ENO1 has the activity of plasminogen binding receptor, and is associated with cell adhesion and integrin beta3 activation. Methods: In lupus mice and interferon α-stimulated cultured podocytes, immunohistochemical and immunofluorescent staining were performed to examined the expression patterns of ENO1 and HK2, and the binding of HK2 and ENO1 by Co-IP. After interfering with siHK2 in cultured podocytes, the intracellular localization of ENO1 and integrin expression were detected. Results: WB and IF showed the downregulation of HK2 and the upregulation of ENO1 in lupus mice and interferon α-stimulated cultured podocytes. In addition, interferon α increase the ENO1 localization on podocyte membrane compared with control group. siHK2 increased the ENO1 localization at the cell membrane surface, accompanied by downregulation of integrins. (Figure) Conclusion: HK2 binds to ENO1 and restricts ENO1 in podocytes. In LN conditions, the dissociation of ENO1 and HK2 leads to an increased localization of ENO1 at the cell membrane, which lead to LN podocyte injury by affecting podocyte adhesion and influencing integrin beta3 expression. Funding: Government Support – Non-U.S.A. The expression patterns of ENO1 and HK2 in mice, Synaptopodin is podocyte mark. B. The expression patterns and the binding of ENO1 and HK2 in cultured podocytes, ENO1 at the podocyte membrane identified by white arrows. C. The expression patterns and the location of ENO1 in cultured podocytes, ENO1 at the podocyte membrane identified by white triangle.