Fig. 1
From: Aging impairs the osteocytic regulation of collagen integrity and bone quality
Bone aging is associated with reduced TGFβ signaling and increased cellular senescence. Unbiased hierarchical pathway clustering of KEGG pathways for the whole transcriptome of male C57BL/6 (WT) mouse bone showed several pathways that were downregulated (a) or upregulated (b) with age, including the downregulated TGFβ signaling pathway. Analysis of individual genes at the transcriptional level showed reduced levels of several genes in the TGFβ signaling pathway (c) and elevated levels of markers of osteocyte senescence and the senescence-associated secretory phenotype (SASP) (d) in bone with age. Multiplexed ELISA of homogenized bone lysate (blue) showed age-related reductions in TGFβ ligand levels in the bone of both males and females (e–h). The circulating TGFβ ligand levels in blood serum (red) remained stable over time in males but showed decreases in females. P < 0.008 using Student’s t test with the Bonferroni correction with respect to (wrt.) 2 months (*), 12 months (#), and 24 months (☨), n = 3-4 per group. e–h *P < 0.008 wrt. 4 months from the same source (bone lysate or serum), ☨P < 0.008 wrt. The age-matched opposite tissue source (lysate vs. serum) in post hoc pairwise Fischer’s LSD test after two-way ANOVA, n = 12–15 per group
