Centrosome proteins form an insoluble perinuclear matrix during muscle cell differentiation
1 Wellcome Trust Centre for Cell Biology, University of Edinburgh, King's Buildings, Edinburgh EH9 3JR, UK
2 University of California, Berkeley, Department of Molecular & Cell Biology, 142 Life Sciences Addition # 3200, Berkeley, CA 94720-3200, USA
3 The Cell Microscopy Centre, Department of Cell Biology and Institute of Biomembranes, University Medical Centre Utrecht, 3584CX Utrecht, The Netherlands
4 Centre National de la Recherche Scientifique-Pierre Fabre, UMR 2587, 3 rue des Satellites, 31400 Toulouse, France
BMC Cell Biology 2009, 10:28 doi:10.1186/1471-2121-10-28Published: 21 April 2009
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.
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.
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.