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  • Title: Essential role of p53 in trophoblastic apoptosis induced in the developing rodent placenta by treatment with a DNA-damaging agent.
    Author: Yamauchi H, Katayama K, Ueno M, He XJ, Mikami T, Uetsuka K, Doi K, Nakayama H.
    Journal: Apoptosis; 2007 Oct; 12(10):1743-54. PubMed ID: 17594519.
    Abstract:
    Placental apoptosis plays important roles in both normal morphogenesis and pathogenesis. We previously reported that administration of cytosine arabinoside (Ara-C), a DNA-damaging agent, to pregnant rats induced apoptosis of trophoblasts in the placental labyrinth zone. Our aim here was to clarify the molecular pathway of DNA damage induced-trophoblastic apoptosis. We found the accumulation and phosphorylation of p53 protein, a tumor suppressor that mediates apoptosis under various cellular stresses, in Ara-C-treated rat placentas. Expression of the mRNAs of downstream targets of p53 was upregulated, suggesting that p53 exerts its function as a transcription factor. We also observed release of mitochondrial cytochrome c and activation of caspase-9, hallmarks of the intrinsic apoptotic pathway. Phosphorylation of Chk1 and H2A.X, target substrates of DNA damage transducers, was detected immediately after Ara-C treatment, suggesting activation of DNA damage cascades to phosphorylate p53. Ara-C-induced trophoblastic apoptosis was almost completely abrogated in placentas of Trp53 (coding p53)-deficient mice, whereas the levels of physiological apoptosis in trophoblasts were similar among wild-type and Trp53-deficient mice. These results indicate that p53 is essential for DNA damage-induced trophoblastic apoptosis and suggest that the mechanisms that regulate the damage-induced apoptosis differ from those that regulate physiological apoptosis.
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