Expression of Bcl-2 and p53 at the fetal-maternal interface of rhesus monkey

Apoptosis plays important roles in placentation and embryonic development [1]. The cells undergoing apoptosis have characteristic structural changes in the nucleus and cytoplasm. The nuclear disintegration involves DNA cleavage into oligonucleosomal length DNA fragments [2-4], and the DNA fragments can be detected by terminal deoxynucleotidyl transferase (TdT)-mediated deoxyuridine triphosphate (dUTP) nick end-labelling (TUNEL) technique. Expressions of apoptotic regulatory molecules, such as Fas, Fas ligand, P53, and the proteins of Bcl-2 family, have been reported in human placenta [5-8]. Bcl-2 and P53 are two of the key players in the apoptotic signaling cascades. Bcl-2, a proto-oncogene first discovered in human follicular lymphoma [9], is involved in the inhibition of apoptosis and the survival of a variety of cell types [10]. Bcl-2 protein is located in the membranes of endoplasmic reticulum, nuclear envelope, and mitochondria. Over-expression of Bcl-2 suppresses apoptosis by preventing the activation of caspases that carry out the process. P53 is well known as a tumor suppressor. It is a transcription factor that induces apoptosis mainly through inducing the expression of a batch of redox-related genes [11] and the down-regulating Bcl-2 [12].The expression of Bcl-2 and P53 human placenta has been studied [1,13]. However, their cellular distribution in the implantation site at early stage of pregnancy has not been reported. Because the monkey and the human share a very similar implantation process in terms of timing, morphological changes, and cell types involved [14], we aimed, in the present study, to investigate the expression, localization of Bcl-2 and P53 in the implantation site of the rhesus monkey, in order to gain some insights to the mechanism of time-dependent apoptosis occurring at the fetal-maternal interface.Healthy adult male and female rhesus monkeys (Macaca mulatta) were purchased from the monkey colony of the Primate Research Center (PRC), Ku