Document Detail

Proteasomes degrade proteins in focal subdomains of the human cell nucleus.
MedLine Citation:
PMID:  16249232     Owner:  NLM     Status:  MEDLINE    
The ubiquitin proteasome system plays a fundamental role in the regulation of cellular processes by degradation of endogenous proteins. Proteasomes are localized in both, the cytoplasm and the cell nucleus, however, little is known about nuclear proteolysis. Here, fluorogenic precursor substrates enabled detection of proteasomal activity in nucleoplasmic cell fractions (turnover 0.0541 microM/minute) and nuclei of living cells (turnover 0.0472 microM/minute). By contrast, cell fractions of nucleoli or nuclear envelopes did not contain proteasomal activity. Microinjection of ectopic fluorogenic protein DQ-ovalbumin revealed that proteasomal protein degradation occurs in distinct nucleoplasmic foci, which partially overlap with signature proteins of subnuclear domains, such as splicing speckles or promyelocytic leukemia bodies, ubiquitin, nucleoplasmic proteasomes and RNA polymerase II. Our results establish proteasomal proteolysis as an intrinsic function of the cell nucleus.
Thomas Dino Rockel; Dominik Stuhlmann; Anna von Mikecz
Publication Detail:
Type:  Journal Article; Research Support, Non-U.S. Gov't     Date:  2005-10-25
Journal Detail:
Title:  Journal of cell science     Volume:  118     ISSN:  0021-9533     ISO Abbreviation:  J. Cell. Sci.     Publication Date:  2005 Nov 
Date Detail:
Created Date:  2005-11-10     Completed Date:  2006-02-21     Revised Date:  2006-11-15    
Medline Journal Info:
Nlm Unique ID:  0052457     Medline TA:  J Cell Sci     Country:  England    
Other Details:
Languages:  eng     Pagination:  5231-42     Citation Subset:  IM    
Institut für Umweltmedizinische Forschung at Heinrich-Heine-University, Auf'm Hennekamp 50, 40225 Düsseldorf, Germany.
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MeSH Terms
Cell Nucleus Structures / enzymology,  metabolism*
Cell Survival
Chromosomal Proteins, Non-Histone / metabolism
Epithelial Cells / cytology
Fibroblasts / cytology
Keratinocytes / cytology
Lamin Type A / metabolism
Lamin Type B / metabolism
Proteasome Endopeptidase Complex / antagonists & inhibitors,  metabolism*
Protein Processing, Post-Translational*
Proteins / metabolism*
Tubulin / metabolism
Ubiquitin / metabolism
Reg. No./Substance:
0/Chromosomal Proteins, Non-Histone; 0/Lamin Type A; 0/Lamin Type B; 0/Proteins; 0/Tubulin; 0/Ubiquitin; 0/fibrillarin; EC Endopeptidase Complex

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