Fig. 5.

A distinct loading-responsive gene module was identified for each age using WGCNA. (A) For each age, RPKM values were used to cluster genes into 38 functional modules. Each age had one module that was significantly enriched for loading (red). The significance threshold (dashed line) was set using a Bonferroni correction (p = .05/38 = .0013); 29% of the genes in these modules were shared between young-adult and old. (B) GO analysis of the loading modules showed high enrichment of collagen-related and osteoblast-related processes (bold: shared between young-adult and old). (C) The top 20 upregulated genes (by fold-change) in each module were induced in both ages but to a lesser magnitude in old mice (white: expression not detected). FE = fold-enrichment; GO = gene ontology; WGCNA = weighted gene co-expression network analysis.