Salidroside stimulates PARP-1 activity. (A) Salidroside fails to reduce H₂O₂-induced DNA strand breaks in Parp-1^−/− cells. Lin⁻ cells were isolated from Brca2^−/−, DNA-PKcs^3A/3A, Fancd2^−/−, Parp-1^−/−, or Xpc^−/− mice. Cells were treated with or without salidroside, NAC, or MnTBAP in the presence of H₂O₂, and subjected to Comet Assay. The mean tail moment of H₂O₂-treated WT sample is expressed as 100%. For each sample, 50 cells were scored from random sampling. (B) Salidroside fails to reduce H₂O₂-induced 8-oxodG in Parp-1^−/− cells. Protein lysates were prepared from low-density BM cells treated as described in panel A. Whole cell lysates were subjected to SDS-PAGE and immunoblotted with antibodies against 8-oxodG and β-actin. (C) Salidroside stimulates Parp-1 activity. Low-density BM cells isolated from mice described in panel A were treated with or without H₂O₂ and salidroside, and BM cells were isolated and subjected to flow cytometry analysis for Parp-1 activity in the LSK population using antibody against PARP-1. (D) Salidroside activates Parp-1 in vivo. Low-density BM cells were isolated from WT mice, and treated with or without SD and H₂O₂ for 2 hours. Whole cell lysates were subjected to immunoprecipitation using PAR antibody. Precipitated samples were resolved by SDS-PAGE and blotted with antibody specific for PARP-1.