Role of Notch expression in premature senescence of murine bone marrow stromal cells

The aim of the present study was to investigate the role of the Notch signaling pathway in premature senescence of murine bone marrow stromal cells in vitro. The intracellular domain of Notch 1 (ICN) was transfected into cultured murine bone marrow stromal cells by lipofectamine transfection. After three days, the proliferation of transfected cells was measured by MTT assay. Cell cycle distribution was analyzed by flow cytometry. Senescence-associated beta-galactosidase (SA-beta-gal) was measured, and the percentage of positive cells was evaluated by assessing 1000 cells in random fields of view. The expressions of p53 and p21(Cip1/Waf1) were analyzed by both RT-PCR and Western blot analysis. The results showed that activation of Notch signaling inhibited proliferation of murine bone marrow stromal cells with induction of G(1) arrest, increased the percentage of SA-beta-gal positive cells, and upregulated p53 and p21(Cip1/Waf1) mRNA and protein expression levels. Thus, the activated Notch signaling could induce premature senescence of bone marrow stromal cells through the p53-p21(Cip1/Waf1) pathway. (C) 2009 National Natural Science Foundation of China and Chinese Academy of Sciences. Published by Elsevier Limited and Science in China Press. All rights reserved.