MicroRNA-126-5p Regulates Proliferation and Apoptosis of IL-22-Stimulated Human Keratinocytes Through Regulating Caspase 1

Abstract

Objective: The study was aimed to explore the roles of miR-126-5p in psoriasis and the underlying molecular mechanisms. Methods: In vitro cell model of psoriasis was established by IL-22 induction. CASP1, the target gene of miR-126-5p, was predicted by TargetScan and verified through the dual luciferase reporter gene system. qRT-PCR was used to measure the mRNA expression of miR-126-5p and CASP1 in IL-22 stimulated HaCaT cells. The protein expression of CASP1, cleaved-caspase3 and caspase3 were measured by Western blot analysis. MTT assay and flow cytometry analysis were performed to detect the cell proliferation and apoptosis. A Caspase3 Activity Assay kit was used to detect the activity of Caspase3. Results: miR-126-5p was high expressed in IL-22 stimulated HaCaT cells compared with normal HaCaT cells. We predicted and verified that CASP1 was a direct target of miR-126-5p, and the mRNA and protein expression of CASP1 were reduced in IL-22 stimulated HaCaT cells compared with the normal HaCaT cells. miR-126-5p inhibitor and CASP1-siRNA significantly decreased the expression of miR-126-5p and CASP1 in HaCaT cells respectively. miR-126-5p inhibitor up-regulated the expression of CASP1 in HaCaT cells, and the effect was reversed by the transfection with CASP1-siRNA. In comparison with the control group, miR-126-5p inhibitor decreased the cell proliferation, induced apoptosis, and improved the activity of Caspase3, enhanced cleaved-caspase3/caspase3 ratio in IL-22 stimulated HaCaT cells, and all the effects were reversed by down-regulating CASP1. Conclusion: We demonstrated that miR-126-5p inhibitor played a protective role in psoriasis by targeting CASP1, evidenced by inhibiting IL-22-induced HaCaT cell proliferation and inducing apoptosis.