Figure 2

Following tail compression, Wnt signaling declined but b-Catenin expression increases. (A) Experimental design/timeline of the 5mo and 12mo old TOPGAL mice subjected to 1 week of tail compression. Red “X” indicates tissue harvest. Letters on the right side of the “X’s” indicate the panels in the timeline. (B) Gene expression of the Wnt ligands in response to compression, listed in decreasing delta CT value with the greatest baseline expression listed first. (C) Eosin/Xgal stain (blue: Wnt active) of 5 and 12 mo IVD subjected to compression (Loaded) or not (Control). (D) Quantification of the fraction of NP (nucleus pulposus) area that is Xgal positive, normalized to internal control in sham-loaded versus control (n = 4/age) and loaded versus control mice (n = 6/age). (E) mRNA expression of b-Catenin, Dkk1 and Axin2 in 5 and 12 mo IVD. (F) IVD were loaded for 1 week, were removed of the compression instrumentation and allowed 3 wk of unencumbered ambulation. (F) Xgal (Blue and blue arrow) staining of Control and Loaded disc. (Top: 5 mo; Bottom: 12 mo) Xgal and IHC of b-Catenin (open arrows are b-catenin without blue color superimposed, black arrows are b-catenin (brown stain) with Wnt activity (blue) superimposed) of a Control and Loaded disc. (G) 5 and 12 mo IVD subjected to compression showing aging and compression reduced mRNA expression of LINC-related elements. ND: not detectable; NP: nucleus pulposus; AF: annulus fibrosus. Scale bar: (C) 100 µm; (F) 5 mo: 25 µm; 12 mo: 50 µm. Data are presented as mean + SD. *Control vs. Loaded; bar: 5 mo vs. 12 mo; p < 0.05.