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Nuclear coiled bodies and the nucleolus. First described in 1903 by Ramon-y-Cajal as silver-staining "accessory bodies" to nucleoli, coiled bodies (CBs) were later rediscovered by e+ectron microscopy.
CBs are ubiquitous, but most abundant in hyperactive and malignant cells. While no specific functions have yet been assigned to CBs, they contain a unique protein, p80-coilin, spliceosome snRNAs and proteins, and the nucleolar protein fibrillarin.
CBs arise from the nucleolus and migrate into the nucleoplasm, implying as yet undefined links between pre-rRNA processing and the spliceosomeassociated Sm proteins in CBs. We are examining CBs in three diverse systems: (1) estrogen stimulated chick liver, (2) normal and neoplastic cells, and (3) polyploid mouse liver. The aim is to ascertain (a) if there are changes in CB frequency related to the above conditions, (b) whether all CBs are homogeneous and nucleoluslinked, and (c) whether relationships exist between NORs and CB frequency. The results show that the range of CBs varies from 0 to >5 in all nuclear types examined even under steady-state conditions. The average number of CBs per nucleus, however, rises and/or declines in concert with presence or absence of hormone, cell confluency, ploidy levels, etc. All CBs seem to originate from nucleoli, but there is a temporal distinction between p80-coilin and fibrillarinrich CBs and the overlapping population. Finally, there may be a balance in non-dividing, polyploid mouse liver nuclei, between the number of active nucleoli, NORs and CBs.
CBs are dynamic and physiologically sensitive organelles, which fluctuate according to the metabolic state of the cell. Supported by NIH grant lR15AI32691.
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