Meta-analysis identifies a MECOM gene as a novel predisposing factor of osteoporotic fracture

Abstract

Background: Osteoporotic fracture (OF) as a clinical endpoint is a major complication of osteoporosis. To screen for OF susceptibility genes, we performed a genome-wide association study and carried out de novo replication analysis of an East Asian population.

Methods: Association was tested using a logistic regression analysis. A meta-analysis was performed on the combined results using effect size and standard errors estimated for each study.

Results: In a combined meta-analysis of a discovery cohort (288 cases and 1139 controls), three hospital based sets in replication stage I (462 cases and 1745 controls), and an independent ethnic group in replication stage II (369 cases and 560 for controls), we identified a new locus associated with OF (rs784288 in the MECOM gene) that showed genome-wide significance (p=3.59×10(-8); OR 1.39). RNA interference revealed that a MECOM knockdown suppresses osteoclastogenesis.

Conclusions: Our findings provide new insights into the genetic architecture underlying OF in East Asians.

Figure 1

Results of the genome-wide association study. The blue-to-red colour gradient reflects lower-to-higher linkage disequilibrium (LD) values (r²). The scatter plot and peak indicate the negative logarithm of p values for each single nucleotide polymorphism (SNP). Overall and discovery p values are represented by red and blue diamonds, respectively. Imputed SNPs are represented by grey circles.

Figure 2

Functional analysis of an siRNA mediated MECOM knockdown in osteoclasts. (A) Cells were grown with 30 ng/ml macrophage colony stimulating factor in the presence or absence of 50 ng/ml receptor activator of nuclear factor κ-B ligand for the indicated times, and real-time PCR was performed. *p<0.05 vs preosteoclasts. (B–D) Cells were transfected with MECOM siRNA or control siRNA using lipofectamine. After incubating cells for an additional 2 days, semiquantitative reverse transcriptase PCR and western blot analysis for MECOM (B), tartrate resistant acid phosphatase (TRAP) staining (C), real-time PCR for TRAP, cathepsin K, matrix metalloproteinase 9 (MMP9), integrin β3, integrin αv, and MECOM (D), and western analysis for TRAP, cathepsin K, and MMP (E) were performed. *p<0.05 vs the control siRNA-treated group; **p<0.05 vs the scrambled siRNA-treated group. All data are expressed as the mean±SE from three independent experiments.