Sequestration of pRb by cyclin D3 causes intranuclear reorganization of lamin A/C during muscle cell differentiation

The A-type lamins that localize in nuclear domains termed lamin speckles are reorganized and antigenically masked specifically during myoblast differentiation. This rearrangement was observed to be linked to the myogenic program as lamin speckles, stained with monoclonal antibody (mAb) LA-2H10, were...

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Bibliographic Details
Published in:Molecular biology of the cell 2005-04, Vol.16 (4), p.1948-1960
Main Authors: Mariappan, Indumathi, Parnaik, Veena K
Format: Article
Language:English
Subjects:
Animals
Carrier Proteins - genetics
Carrier Proteins - metabolism
Cell Differentiation
Cell Line
Cyclin D3
Cyclins - genetics
Cyclins - metabolism
Humans
Lamin Type A - genetics
Lamin Type A - metabolism
MADS Domain Proteins
MEF2 Transcription Factors
Mice
Muscle Development
Myoblasts - cytology
Myoblasts - metabolism
Myogenic Regulatory Factors - genetics
Myogenic Regulatory Factors - metabolism
Nerve Tissue Proteins - genetics
Nerve Tissue Proteins - metabolism
Phosphorylation
Rats
Retinoblastoma Protein - metabolism
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Summary:The A-type lamins that localize in nuclear domains termed lamin speckles are reorganized and antigenically masked specifically during myoblast differentiation. This rearrangement was observed to be linked to the myogenic program as lamin speckles, stained with monoclonal antibody (mAb) LA-2H10, were reorganized in MyoD-transfected fibroblasts induced to transdifferentiate to muscle cells. In C2C12 myoblasts, speckles were reorganized early during differentiation in cyclin D3-expressing cells. Ectopic cyclin D3 induced lamin reorganization in C2C12 myoblasts but not in other cell types. Experiments with adenovirus E1A protein that can bind to and segregate the retinoblastoma protein (pRb) indicated that pRb was essential for the cyclin D3-mediated reorganization of lamin speckles. Cyclin D3-expressing myoblasts displayed site-specific reduction of pRb phosphorylation. Furthermore, disruption of lamin structures by overexpression of lamins inhibited expression of the muscle regulatory factor myogenin. Our results suggest that the reorganization of internal lamins in muscle cells is mediated by key regulators of the muscle differentiation program.
ISSN:1059-1524
1939-4586
DOI:10.1091/mbc.E04-02-0154