Altered MicroRNA Profile in Osteoporosis Caused by Impaired WNT signaling

WNT signaling is fundamental to bone health and its aberrant activation leads to skeletal pathologies. A heterozygous missense mutation p.C218G in WNT1, a key WNT pathway ligand, leads to severe early-onset osteoporosis with multiple peripheral and spinal fractures. Despite the severe skeletal manifestations, conventional bone markers are normal in mutation-positive patients. The objective of this study was to find novel biomarkers that differentiate between WNT1 mutation-positive and -negative subjects. We evaluated serum levels of 192 miRNAs in 12 mutation-positive (median age 39 years, range 11-76 years) and 12 mutation-negative (35 years, range 9-59 years) subjects from two Finnish families. The results indicate significant differences in circulating miRNA profiles with 2 upregulated (miR-18a-3p, miR-223-3p) and 6 downregulated miRNAs (miR-22-3p, miR-31-5p, miR-34a-5p, miR-143-5p miR-423-5p, miR 423-3p) in the mutation-positive subjects. Three of these (miR-22-3p, miR-34a-5p, and miR-31-5p) are known inhibitors of WNT signaling: miR-22-3p and miR-34a-5p target WNT1 mRNA and miR-31-5p is predicted to bind to the WNT1 3’UTR. Our results suggest that the WNT1 mutation disrupts a feed-back regulation between these miRNAs and WNT1, providing new insights into the pathogenesis of WNT-related bone disorders. Future studies are warranted to explore the potential diagnostic and therapeutic applications of these findings in osteoporosis. Cross-sectional design comparing serum microRNA profiles of 12 subjects with heterozygous missense mutation p.C218G in WNT1 to a control group with wildtype WNT1.