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The p53 protein plays a central role in regulating apoptosis. The loss of functional p53 is common in many cancers. In cancer cells, the dysfunctional p53 protein often maintains a misfolded, inactive conformation due to genetic mutations or posttranslational deregulation. The misfolded p53 protein can aggregate and form amyloid-like oligomers and fibrils, which abrogate the pro-apoptotic functions of p53. Therefore, the aggregation of p53 may be a crucial factor in carcinogenesis, tumor progression, and the response of cancer cells to apoptotic signals. In this chapter, we provide details on various methods for detecting p53 aggregation in cancer cell lines and tumor samples.

p53 is a key transcriptional mediator that controls the expression of hundreds of target genes necessary to maintain cellular homeostasis and genome integrity. An important cellular function that is dependent on p53 transcriptional activity is apoptosis or programmed cell death. Indeed, inhibition of p53 transcriptional activity is often observed in cancers as a result of mutations within its DNA-binding domain. In this chapter, we describe the use of chromatin immunoprecipitation and real-time quantitative polymerase chain reaction to detect p53 transcriptional activity in cancer cells and tumor tissues. This technique enables the determination of the ability of p53 to bind to the promoter region of apoptotic genes and to evaluate the transcription-dependent activity of p53-induced apoptosis.

Apoptosis occurs in the villous trophoblast of normal placentas throughout pregnancy, but with higher frequency near term in comparison to the first trimester. In pregnancies complicated by preeclampsia or intrauterine growth restriction (IUGR), a greater incidence of villous and extravillous trophoblast apoptosis has been observed, suggesting that the deregulation of trophoblast apoptosis may contribute to pathological conditions. Apoptosis may be initiated by one of two known pathways, the mitochondrial (instrinsic) pathway and the death receptor-mediated (extrinsic) pathway, or in response to exogenous stimuli such as cytokines or hypoxia. The central executioners of apoptosis are the caspase family of cysteine proteases, which cleave numerous vital cellular proteins to affect the apoptotic cascade. By controlling caspase activation, several endogenous inhibitors, including FLIP, IAPs and anti-apoptotic Bcl-2 family members prevent further propagation of the death signal. This review focuses on the molecular mechanisms by which normal trophoblast apoptosis occurs and how it is regulated to avoid excessive trophoblast apoptosis and pregnancy complications.

Medawar, in the early 1950s, recognized for the first time, the unique immunology of the maternal-fetal interface and its potential relevance for transplantation. In his original work, he described the “fetal allograft analogy” whereby the fetus may be viewed as a semi-allogeneic conceptus that has evaded rejection by the maternal immune system. Although numerous hypotheses have been proposed to prove this observation, none have demonstrated that the maternal immune system is antagonist to the invading trophoblast. In the present manuscript we have reviewed recent studies demonstrating the expression and function of TLRs in trophoblast cells and based on this data we propose an alternative view for maternal-fetal immune interactions.