Centrosome proteins form an insoluble perinuclear matrix during muscle cell differentiation.
BACKGROUND
Muscle fibres are formed by elongation and fusion of myoblasts into myotubes. During this differentiation process, the cytoskeleton is reorganized, and proteins of the centrosome re-localize to the surface of the nucleus. The exact timing of this event, and the underlying molecular mechanisms are still poorly understood.


RESULTS
We performed studies on mouse myoblast cell lines that were induced to differentiate in culture, to characterize the early events of centrosome protein re-localization. We demonstrate that this re-localization occurs already at the single cell stage, prior to fusion into myotubes. Centrosome proteins that accumulate at the nuclear surface form an insoluble matrix that can be reversibly disassembled if isolated nuclei are exposed to mitotic cytoplasm from Xenopus egg extract. Our microscopy data suggest that this perinuclear matrix of centrosome proteins consists of a system of interconnected fibrils.


CONCLUSIONS
Our data provide new insights into the reorganization of centrosome proteins during muscular differentiation, at the structural and biochemical level. Because we observe that centrosome protein re-localization occurs early during differentiation, we believe that it is of functional importance for the reorganization of the cytoskeleton in the differentiation process.
Srsen
Vlastimil
V
Wellcome Trust Centre for Cell Biology, University of Edinburgh, King's Buildings, Edinburgh, UK. vsrsen@staffmail.ed.ac.uk
Fant
Xavier
X
Heald
Rebecca
R
Rabouille
Catherine
C
Merdes
Andreas
A
D000818:Animals; D018797:Cell Cycle Proteins / Q000378:metabolism; D002454:Cell Differentiation; D002460:Cell Line; D002467:Cell Nucleus / Q000378:metabolism; D018385:Centrosome / Q000737:chemistry* / Q000378:metabolism; D003598:Cytoskeletal Proteins / Q000032:analysis*; D051379:Mice; D008869:Microtubule-Associated Proteins / Q000378:metabolism; D008870:Microtubules / Q000378:metabolism; D032446:Myoblasts / Q000737:chemistry* / Q000166:cytology / Q000648:ultrastructure
D018797:Cell Cycle Proteins; D003598:Cytoskeletal Proteins; D008869:Microtubule-Associated Proteins; C490114:Pcm1 protein, mouse