Multinucleated cells can continuously generate mononucleated cells in the absence of mitosis: a study of cells of the avian osteoclast lineage.
The multinucleated bone-resorbing osteoclast has a hematopoietic origin. We have demonstrated previously that osteoclasts are derived from the monocytic lineage by fusion of mononuclear macrophage precursors. Using an in vitro-osteoclast differentiation model derived from pure populations of chick macrophage cultures, osteoclast-like multinucleated giant cells (MNGCs) can be formed by fusion following an active proliferation phase. However, after reaching a peak with 70% of the culture being MNGCs, a new round of expansion of the mononuclear cells is observed. The following experiments suggest that these mononuclear cells were derived directly from the MNGCs by a budding process, selectively from the central zone of the apical surface. After microinjection of the membrane-impermeable probe, Lucifer Yellow, into single MNGCs, initially only diffuse fluorescence, limited to the whole MNGC injected, was observed. However, after 24-48 hours fluorescent mononuclear cells were observed adjacent but distinct from the injected MNGC. To confirm that these mononuclear cells were indeed derived from a parent MNGC, single MNGCs were cloned into single wells. Within a week, the MNGC was surrounded by mononuclear cells, which eventually populated the entire well. These mononuclear cells could then give rise to a second generation of MNGCs following a three-week period of culture. To determine whether this process required mitosis, MNGCs were cultured for three days in the presence of the mitotic inhibitor, Ara-C, prior to microinjection with Lucifer Yellow. Fluorescent mononuclear cells were still seen to arise from a single injected MNGC under these conditions.(ABSTRACT TRUNCATED AT 250 WORDS)
Solari
F
F
Département de Biologie Moléculaire et Cellulaire, Ecole Normale Supérieure, Lyon, France.
Domenget
C
C
Gire
V
V
Woods
C
C
Lazarides
E
E
Rousset
B
B
Jurdic
P
P
D000818:Animals; D002454:Cell Differentiation; D002459:Cell Fusion; D002467:Cell Nucleus; D002478:Cells, Cultured; D002645:Chickens; D015726:Giant Cells / Q000166:cytology*; D008264:Macrophages / Q000166:cytology*; D018613:Microscopy, Confocal; D008938:Mitosis; D010010:Osteoclasts / Q000166:cytology*