A functional polymorphism at miR‑491‑5p binding site in the 3'UTR of MMP9 gene confers increased risk for pressure ulcers after hip fracture.

Abstract

The roles of matrix metalloproteinase (MMP)9 in the control of pressure ulcers(PU) after hip fracture as well as how the rs1056629 in MMP9 3'UTR compromises the interaction between MMP9 and miR‑491 were explored. Online miRNA database (http://www.bioguo.org) was utilized to explore gene polymorphism in MMP9 3'UTR that might break the interaction between MMP9 and miRNA. Luciferase assay was utilized to confirm the miRNA targeted MMP9. Real‑time PCR, westernblot analysis and immunohistochemistry were carried out to understand the roles of MMP9 in PU as well as how rs1056629 in MMP9 3'UTR compromises the interaction between MMP9 and miR‑491. rs1056629 in MMP9 3'UTR that compromised the interaction between MMP9 and four miRNAs including miR‑194‑3p, miR‑491, miR‑1915‑3p and miR‑941, and only miR‑491 among miR‑194‑3p, miR‑491, miR‑1915‑3p and miR‑941 decreased luciferase activity of wild‑type MMP9 3'UTR, and luciferase activities of mutant‑3 and mutant‑4 MMP9 3'UTR in miR‑491 overexpressing cells was comparable with scramble control. miR‑194‑3p, miR‑491, miR‑1915‑3p and miR‑941 levels in PU group was comparable with healthy control, and miR‑194‑3p, miR‑491, miR‑1915‑3p and miR‑941 in subjects carrying AA genotype was similar with those in AC and CC groups. MMP9 mRNA and protein, and histology score in subjects with PU were much higher, and were also much higher in AA group. Only miR‑491 mimic among miR‑194‑3p, miR‑491, miR‑1915‑3p and miR‑941 mimics downregulated the MMP9 level, and only miR‑491 inhibitor among miR‑194‑3p, miR‑491, miR‑1915‑3p and miR‑941 inhibitors upregulated the MMP9 level. Our study indicated that rs1056629 polymorphism could be a novel biomarker for predicting the occurrence of PU after a hip fracture.