hsa-miR-155 targeted NCSTN 3'UTR mutation promotes the pathogenesis and development of acne inversa

To investigate molecular mechanisms of nicastrin (NCSTN) mutations inducing acne inversa (AI).

New and old lesional and non-lesional skin samples were obtained from an AI patient. Healthy skin samples were obtained from the buttocks of 100 non-AI patients. Hematoxylin-eosin staining and immunohistochemistry of NCSTN protein were examined. All exon-intron and exon boundary sequences were polymerase chain reaction (PCR) -amplified and sequenced. Bioinformatic analyses of NCSTN 3'-untranslated regions (3'UTR) were conducted using RegRNA2.0. 3'UTR of NCSTN was cloned vector of psiCHECK-2 vector; the mutant 3'UTR NCSTN-psiCHECK-2 was constructed on a template of NCSTN 3'UTR. A dual-luciferase reporter gene assay, real-time reverse transcription (qRT)-PCR and Western blot analysis were conducted to evaluate functional changes associated with the mutation.

We identified a novel deletion mutation of the NCSTN gene in the NCSTN 3'UTR region (designated c.2584-2585del CA) at the binding site of human micro-RNA-155 (hsa-miR-155). Levels of NCSTN protein were potently lower in epidermis and hair follicles of AI patients with lesions than in healthy skin. The hsa-miR-155+mutant NCSTN significantly downregulated in dual luciferase assay, qRT-PCR, and Western blot. The novel deletion mutation was confirmed to be a pathological cause of AI.

miR-155 downregulates the expression of NCSTN by binding NCSTN 3'UTR, providing a possible new mechanism of loss of NCSTN function in AI patients. hsa-miR-155 functions as a promoter in AI, and is a potential therapy target for AI.