The tissue dependent interactions between p53 and Bcl-2 in vivo

To further investigate the role of p53 in apoptosis in vivo and the interaction between p53 and Bcl-2 in the regulation of cellular apoptosis in vivo, we depleted p53 in Bcl-2-null mice. We found that the interaction between p53 and Bcl-2 are tissue dependent. Specifically, loss of p53 in Bcl-2(−/−) mice inhibits apoptotic induction in spleen and subsequently inhibits the Bcl-2-null-induced spleen atrophy. Furthermore, p53 deficiency overcomes loss of melanocyte stem cell (MSC)-induced apoptosis and subsequently prevents hair graying in Bcl-2- null mice. In addition, p53 deletion partly inhibits apoptosis in hair follicle keratinocytes, leading to the alleviation of hair growth delay in Bcl-2-null mice. However, p53 absence in Bcl-2-null mice cannot restore other defects in Bcl-2-null mice, including retardation of growth, short ears and polycystic kidney disease.