Nuclei of non-muscle cells bind centrosome proteins upon fusion with differentiating myoblasts.
BACKGROUND
In differentiating myoblasts, the microtubule network is reorganized from a centrosome-bound, radial array into parallel fibres, aligned along the long axis of the cell. Concomitantly, proteins of the centrosome relocalize from the pericentriolar material to the outer surface of the nucleus. The mechanisms that govern this relocalization are largely unknown.


METHODS
In this study, we perform experiments in vitro and in cell culture indicating that microtubule nucleation at the centrosome is reduced during myoblast differentiation, while nucleation at the nuclear surface increases. We show in heterologous cell fusion experiments, between cultures of differentiating mouse myoblasts and human cells of non-muscular origin, that nuclei from non-muscle cells recruit centrosome proteins once fused with the differentiating myoblasts. This recruitment still occurs in the presence of cycloheximide and thus appears to be independent of new protein biosynthesis.


CONCLUSIONS
Altogether, our data suggest that nuclei of undifferentiated cells have the dormant potential to bind centrosome proteins, and that this potential becomes activated during myoblast differentiation.
Fant
Xavier
X
Wellcome Trust Centre for Cell Biology, University of Edinburgh, Edinburgh, United Kingdom.
Srsen
Vlastimil
V
Espigat-Georger
Aude
A
Merdes
Andreas
A
D000818:Animals; D018797:Cell Cycle Proteins / Q000378:metabolism*; D002454:Cell Differentiation; D002459:Cell Fusion; D002460:Cell Line; D002467:Cell Nucleus / Q000378:metabolism*; D018385:Centrosome / Q000378:metabolism*; D006801:Humans; D051379:Mice; D008870:Microtubules / Q000378:metabolism; D008954:Models, Biological; D032342:Muscle Cells / Q000166:cytology* / Q000378:metabolism*; D018485:Muscle Fibers, Skeletal / Q000166:cytology / Q000378:metabolism; D032446:Myoblasts / Q000166:cytology* / Q000378:metabolism; D009685:Nuclear Envelope / Q000378:metabolism; D011485:Protein Binding; D014176:Protein Biosynthesis; D021381:Protein Transport
D018797:Cell Cycle Proteins