Centrosomal proteins are reorganized in fused trophoblastic cells. (LB57)

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Cell‐cell fusion is a cardinal event in the formation of multinucleate syncytia and is part of the normal biology of the syncytiotrophoblast (STB) layer of the human placenta. We have found numerous differences between non‐fused and fused trophoblastic cells in culture.We have now compared centrosomal proteins and microtubules in non‐fused and fused BeWo cells. In non‐fused BeWo cells, the centrosomal proteins, pericentrin and gamma‐tubulin, were present as one or two perinuclear dot‐like structures. Following forskolin‐induced cell fusion, the immunofluorescence labeling pattern for pericentrin and gamma‐tubulin was dramatically altered and appeared to increase in amount and had a “cloud‐like” distribution. Microtubule nucleation experiments in which microtubules regrow following depolymerization with nocodazole were conducted. In non‐fused cells, microtubules regrow from the single microtubule organization center (MTOC). However, in fused cells there were multiple sites of regrowth corresponding to pericentrin and gamma‐tubulin positive‐foci. Examination of human placental tissue revealed that centrosomal proteins in the STB were distributed in a manner similar to that found in fused BeWo cells while mononuclear cells within the placenta have MTOCs similar to those in non‐fused BeWo cells. Thus the cell culture model recapitulates the novel situation in the tissue.Grant Funding Source: Supported by NIH RO1HD058084