miR-125b is downregulated in systemic lupus erythematosus patients and inhibits autophagy by targeting UVRAG

Abstract

Systemic lupus erythematosus (SLE) is a severe autoimmune disease and the pathogenesis remains incompletely understood. This study aimed to investigate the role of miR-125b in the pathogenesis of SLE and explore the underlying mechanism. Compared to healthy controls, the expression of miR-125b decreased in peripheral blood mononuclear cells (PBMCs) of SLE patients. In addition, PBMCs exposed to ultraviolet B had lower miR-125b level compared to those unexposed to radiation. We identified UV radiation resistance associated gene (UVRAG) as a target of miR-125b. Jurkat cells treated with miR-125b-5p agomir showed reduced levels of ATG7, Beclin-1 and LC3 II and decreased autophagy. In contrast, Jurkat cells treated with miR-125b-5p antagomir showed increased levels of ATG7, Beclin-1 and LC3 II and increased autophagy. Furthermore, Jurkat cells transfected with UVRAG expression vector showed higher expression of ATG7, Beclin-1 and LC3 II and increased autophagy. Conversely, cells transfected with UVRAG siRNA had lower expression of ATG7, Beclin-1 and LC3 II and decreased autophagy. Taken together, our data demonstrate that Ultraviolet B radiation can downregulate miR-125b-5p and increase UVRAG expression and autophagy activity in PBMCs of SLE patients. These findings help explain how ultraviolet B exacerbates SLE and suggest that UVRAG is a potential therapeutic target for SLE.

Keywords: Autophagy; Systemic lupus erythematosus; UV radiation resistance associated gene; Ultraviolet B; miR-125b.