Downregulation of miR-633 activated AKT/mTOR pathway by targeting AKT1 in lupus CD4⁺ T cells

Accumulating evidence suggests that the AKT/mTOR pathway plays an important role in the pathogenesis of systemic lupus erythematosus (SLE) through activating T cells, and there are few studies looking into the role of microRNA (miRNAs) in the mechanism. We first found that miR-633 expression in CD4⁺T cells of SLE patients was significantly reduced.

To investigate the role of miR-633 in the AKT/mTOR pathway in lupus CD4⁺T cells.

Samples of 17 SLE cases and 16 healthy controls were collected to detect the expression of miR-633, AKT1, mTOR mRNA and proteins by quantitative polymerase chain reaction (qPCR) and Western-blot, respectively. To determine whether AKT1 is a direct target of miR-633, a luciferase assay was performed. In vitro, AKT1 siRNA, miR-633 mimics/inhibitors or negative controls were transfected to Jurkat cells, human primary CD4⁺T cells and lupus CD4⁺T cells. RNA and proteins were extracted after 48 h, and levels of AKT/mTOR pathway markers and downstream multiple cytokines were detected by qPCR or Western-blot.

In SLE patients, the miR-633 levels in CD4⁺T cells were significantly decreased and negatively correlated with SLEDAI. AKT1, mTOR mRNA and proteins were all up-regulated. The degree of downregulation of miR-633 was correlated negatively with AKT1 mRNA. The luciferase assay proved that AKT1 is a direct target of miR-633. In Jurkat and lupus CD4⁺T cells, overexpression of miR-633 could result in lower levels of AKT1 and mTOR. Inhibition of miR-633 expression in primary CD4⁺T cells caused reverse effects, and protein levels of p-AKT, p-mTOR, and p-S6RP increased. Moreover, among various cytokines, the expression of IL-4, IL-17, and IFN-γ mRNA was raised.

Our study suggests that miR-633 deletion can activate the AKT/mTOR pathway by targeting AKT1 to participate in the pathogenesis of SLE.