Figure 6
From: Fam64a is a novel cell cycle promoter of hypoxic fetal cardiomyocytes in mice
Nuclear Fam64a in dividing fetal cardiomyocytes (fCMs) rapidly disappears during metaphase-to-anaphase transition. (a) A representative time-lapse recording of cell division dynamics of E15 fCMs transduced with Fam64a-GFP baculovirus. A steady nuclear signal of Fam64a in an interphase fCM at time 0 rapidly disappeared before the onset of anaphase at 25 min. The fCM subsequently completed mitosis and cytokinesis, but the Fam64a signal never reappeared. (b) A representative time-lapse recording of cell division dynamics of E15 fibroblasts transduced with Fam64a-GFP baculovirus. The Fam64a signal disappeared upon completion of mitosis (arrows), which was a later time point than observed for the fCMs in (a). (c) Isolated E16 fCMs were triple-stained with Fam64a, α-actinin, and DAPI. DAPI staining clearly defined each phase in mitosis, including prophase, metaphase, anaphase, telophase, and subsequent cytokinesis. In interphase CMs, Fam64a expression was restricted to nuclei (arrow) with a faint background signal in the cytoplasm. At this time point, the sarcomere structure was intact, as indicated by α-actinin staining. In prophase, when chromosome condensation was visible as dot-like puncta by DAPI staining (arrow), Fam64a was still expressed in the CM nuclei (arrow). However, during the metaphase-to-anaphase transition, the Fam64a signal rapidly disappeared (arrow) and never reappeared thereafter, while the background signal remained unchanged. Sarcomere structure was grossly perturbed during cell division. Scale bars = 30 µm in (a,b) and 20 µm in (c). In (a) and (b), the number on each panel indicates the time in (hours: minutes) elapsed from the time indicated in the first panel.
