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Fig. 9. xPTP-PESTr overexpression inhibits fibronectin fibrillogenesis and perturbs orientation of cell division. Blastocoel roofs (BCR) from embryos
expressing GFP, Wt-, or C231S-PTP-PEST were dissected at Stage 12, fixed, and processed for immunofluorescence. The FN fibrils of the BCR were detected
using a rabbit polyclonal antibody (32F; A–C). (D–F) Nuclei staining of the same fields as in A–C using DAPI. (A) BCR of GFP injected embryo shows
well-developed FN fibrils that connect each cell with its neighbors. (B) The BCR overexpressing wild-type xPTP-PESTr have FN only at cell –cell contacts
(arrowhead). (C) The BCR overexpressing C231S displays three types of fibrils: long fibrils that cross over up to three cells (arrowhead), very short fibrils with
more branching (arrow) and groups of parallel fibrils (double arrow and inset). (D) Nuclei staining of control cells reveals anaphase figures exclusively in the
plane of the BCR (double arrows). (E) BCR cells overexpressing Wt-PTP-PEST presents random cell division polarity: the metaphase plates show angles of
90j (arrow 1), 45j (arrow 2), or 0j (arrow 3) to the blastocoel roof plane. (F) In BCR overexpressing the C321S point mutant, cell divisions occur, as for the
control, along the BCR plane (double arrows). |
