Cleaved parp 1

To study phosphorylation and expression of proteins in osteoclasts, BMMs were induced with RANKL for different time points as described in the figures and the total cell lysates were prepared in cell lysis buffer (Cell Signaling Technology, Danvers, MA, USA). Protein concentration was determined and equal amount of protein was applied onto SDS-PAGE. After the transfer, membranes were blocked in 5% skimmed milk for 1 h at room temperature, followed by probing with specific primary antibody primary antibodies in 5% BSA in PBS-Tween (1% v/v) overnight and then washed three times with PBS-Tween (PBST) and probed with secondary antibodies from LI-COR (Odyssey Imager; donkey anti-rabbit/IRDye 800 CW/anti-goat/IRDye 800 CW anti-mouse IRDye 680 CW) for 1 h at room temperature. Membranes were then washed three times with PBST and scanned by using LI-COR Odyssey Imager (LI-COR Biosciences, Lincoln, NE, USA). The RBPJ, NEMO, IKK2, pIκB, IκB and cleaved PARP1 antibodies were purchased form Santa Cruz, Dallas, TX, USA; Cleaved Caspase 3 antibody was purchased from Cell Signaling Technology, Danvers, MA, USA; β-actin was purchased from Sigma, St Louis, MO, USA.

The MSCs were lysed using RIPA lysis buffer (Thermo Fisher Scientific, Waltham, MA, USA) to obtain total cellular protein. Cell lysates (20 µg of total protein) were separated on 8–12% sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE), and the proteins were transferred to the nitrocellulose membrane. After the blots had been washed with TBST (10 mM Tris-HCl (pH 7.60), 150 mM NaCl, 0.05% Tween-20), they were blocked with 5% skimmed milk for 1 h and incubated with appropriate primary antibodies at the dilutions recommended by the supplier. Antibodies against GRP78, PERK, p-PERK, eIF2α, p-eIF2α, ATF4, IRE1α, CHOP, p-IRE1α, NF-κB, p-NF-κB, JNK, p-JNK, p38, p-p38, BCL-2, BAX, cleaved caspase-3, cleaved PARP-1, PrP^C, MnSOD, and β-actin were purchased from Santa Cruz Biotechnology (Dallas, TX, USA). The membranes were then washed, and primary antibodies were detected using goat anti-rabbit IgG or goat anti-mouse IgG conjugated to horseradish peroxidase (Santa Cruz Biotechnology). The immunoreactive bands were visualized by enhanced chemiluminescence (Amersham Pharmacia Biotech, Little Chalfont, UK).