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Mutational analysis of p80 coilin indicates a functional interaction between coiled bodies and the nucleolus

Coiled bodies are conserved subnuclear domains found in both plant and animal cells. They contain a subset of splicing snRNPs and several nucleolar antigens, including Nopp140 and fibrillarin. In addition, autoimmune patient sera have identified a coiled body specific protein, called p80 coilin. In...

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Detalles Bibliográficos
Formato: Texto
Lenguaje:English
Publicado: The Rockefeller University Press 1995
Materias:
Acceso en línea:https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2200013/
https://www.ncbi.nlm.nih.gov/pubmed/7490287
Descripción
Sumario:Coiled bodies are conserved subnuclear domains found in both plant and animal cells. They contain a subset of splicing snRNPs and several nucleolar antigens, including Nopp140 and fibrillarin. In addition, autoimmune patient sera have identified a coiled body specific protein, called p80 coilin. In this study we show that p80 coilin is ubiquitously expressed in human tissues. The full-length human p80 coilin protein correctly localizes in coiled bodies when exogenously expressed in HeLa cells using a transient transfection assay. Mutational analysis identifies separate domains in the p80 coilin protein that differentially affect its subnuclear localization. The data show that p80 coilin has a nuclear localization signal, but this is not sufficient to target the protein to coiled bodies. The results indicate that localization in coiled bodies is not determined by a simple motif analogous to the NLS motifs involved in nuclear import. A specific carboxy-terminal deletion in p80 coilin results in the formation of pseudo-coiled bodies that are unable to recruit splicing snRNPs. This causes a loss of endogenous coiled bodies. A separate class of mutant coilin proteins are shown to localize in fibrillar structures that surround nucleoli. These mutants also lead to loss of endogenous coiled bodies, produce a dramatic disruption of nucleolar architecture and cause a specific segregation of nucleolar antigens. The structural change in nucleoli is accompanied by the loss of RNA polymerase I activity. These data indicate that p80 coilin plays an important role in subnuclear organization and suggest that there may be a functional interaction between coiled bodies and nucleoli.