Mitsuko Masutani

Differential expression of angiogenic and vasodilatory factors by invasive trophoblast giant cells depending on depth of invasion

The uterine bed undergoes remarkable changes during pregnancy, including proliferation and decidualization of the uterine stroma and remodeling and angiogenesis of the maternal vasculature. Fetal‐derived trophoblast giant cells invade into the uterus where they gain access to the maternal blood circulation to ensure sufficient nutrient supply of the embryo. In serial sections through early‐ to mid‐gestation conceptuses, we have determined the exact distance of trophoblast invasion and the expression of angiogenic, vasodilatory, and anticoagulative factors that are likely to influence remodeling and redirection of the maternal circulatory system. Trophoblast derivatives were detected at a distance as far as ∼300 μm from the placental border, where they are allocated exclusively along the mid‐line of the decidua. The farthest invading cells characteristically expressed proliferin and proliferin‐related protein, hormones that affect endothelial cell migration and vascularization. Occasionally, these cells replaced the normal vascular endothelium and acquired a “pseudo‐endothelial” shape. Complete vascular disintegration was observed 50–80 μm outside of the placental border where maternal blood was entirely lined by a trophoblast giant cell‐derived network of blood sinuses. This transition in blood space lining correlated with trophoblast expression of various vasodilatory and anticoagulative factors that are likely to promote blood flow toward the placenta. Analysis of teratocarcinoma‐like tumors demonstrated that trophoblast giant cell‐induced promotion and redirection of blood flow is not restricted to the uterine environment. These results show that trophoblast giant cells have the intrinsic capacity to attract and increase blood flow and to gradually displace the vascular endothelium resulting in the formation of canals entirely lined by trophoblast cells. Developmental Dynamics 227:185–191, 2003.

Role of Poly-ADP-Ribosylation in Cancer Development

Elucidation of the relationship between poly-ADP-ribosylation and carcinogenesis has markedly progressed by the recent development of knockout or transgenic mice models of poly(ADP-ribose) polymerase (Parp)-1, Parp-2, and poly(ADP-ribose) glycohydrolase (Parg). Parp-1 is involved in base excision repair (BER), single- and |double-strand break repair, and chromosomal stability. These multiple functions explain why Parp-1 deficiency enhances carcinogenesis induced by alkylating agents and that in aged animals. Parp-1 is also involved in transcriptional regulation through protein-protein interaction as a coactivator and/or poly-ADP-ribosylation reaction and is possibly involved in epigenetic alteration during carcinogenesis and modulation of tumor phenotypes. Parp-1-dependent cell-death accompanying NAD depletion may be another important issue in carcinogenesis because this process could lead to the selection of Parp-1 deficient cells due to their survival advantage during cancer growth. The relationship of Parp-2, Parp-3, tankyrase and Parg with carcinogenesis is also discussed.

Poly(ADP-ribose) Preparation Using Anion-Exchange Column Chromatography

Poly(ADP-ribose) polymerase (PARP) polyADP-ribosylates proteins involved in various physiological processes. Accumulated evidence suggests not only protein-conjugated poly(ADP-ribose) but also protein-free poly(ADP-ribose) function in various physiological processes. There are increasing occasions that require protein-free poly(ADP-ribose) to study the function and dynamics of poly(ADP-ribose) in cells. However, the availability of poly(ADP-ribose) is still limited because a chemical synthesis method has not been established. Here, we describe an improved method for the preparation of protein-free poly(ADP-ribose), synthesized enzymatically by using a recombinant PARP-1 expression system and purified with an anion-exchange column chromatography. This method will be useful for biochemical and biological investigation of poly(ADP-ribose) functions and dynamics.