Journal: eLife
Article Title: Disparate bone anabolic cues activate bone formation by regulating the rapid lysosomal degradation of sclerostin protein
doi: 10.7554/eLife.64393
Figure Lengend Snippet: ( A ) Fifteen week old male C57Bl/6 mice treated with vehicle (saline + 4% DMSO, n = 7 mice) or bafilomycin A1 (1 mg/kg, n = 7 mice) to inhibit lysosomal degradation were forearm loaded (2000 με, 90 s, 2 Hz) and labeled with calcein and alizarin red at the indicated times for dynamic histomorphometry. Representative periosteal double labeling are shown. ( B ) Periosteal bone formation rate (Ps.BFR) and ( C ) periosteal mineral apposition rate (Ps.MAR) were calculated. ( D ) Fourteen to 17 week old male and female C57Bl/6 mice treated with vehicle (saline + 4% DMSO, i.p., n = 14) or bafilomycin A1 (1 mg/kg in saline + 4% DMSO, i.p., n = 12 mice) to inhibit lysosomal degradation were treated 2 hr prior to ulnar loading (2000 με, 90 s, 2 Hz). Non-loaded and loaded limbs were isolated 5 min post-load, and western blots were probed for sclerostin and β-actin. Vehicle data is duplicated in as all animals were run and processed together. ( E ) Human iPSC-derived osteoblasts from either control (non-diseased) or Gaucher disease patients were treated with vehicle or recombinant glucocerebrosidase (rGCase, 0.24 U/mL) for 5 days, then lysed for western blotting. Western blots were probed for sclerostin and GAPDH (n = 3 independent patient-derived iPSC lines/group). Graphs depict mean ± SD. *p<0.05, **p<0.01 by two-way ANOVA with Holm–Sidak post hoc correction ( B , C , and E ) or Kruskal–Wallis with Dunn’s post hoc correction ( D ). ( F ) FSS causes the rapid degradation of sclerostin protein by the lysosome through a number of molecular mediators. PTH, converging with this FSS mechano-transduction pathway at CaMKII, also mediates the lysosomal degradation of sclerostin protein. Icons outlined red are molecular mechanisms controlling sclerostin abundance that have been described within this manuscript that integrate into our previously described mechano-transduction cascade. Osteoanabolic stimuli, working through reactive oxygen (ROS) and reactive nitrogen species (RNS), direct sclerostin to the lysosome for degradation. This results in reduced sclerostin to allow for bone formation. PM: plasma membrane; ROS: reactive oxygen species; NO: nitric oxide.
Article Snippet: Antibody , Rabbit Polyclonal Anti-Total CaMKII , Cell Signalling Technology , 3362S RRID: AB_2067938 , (1:1000).
Techniques: Saline, Labeling, Isolation, Western Blot, Derivative Assay, Control, Recombinant, Transduction, Clinical Proteomics, Membrane