Document Detail

Differentiation of Trypanosoma brucei may be stage non-specific and does not require progression of cell cycle.
MedLine Citation:
PMID:  12823826     Owner:  NLM     Status:  MEDLINE    
Ubiquitination and proteasomal degradation of cell cycle regulatory proteins are known to play a pivotal role in controlling the progression of the eukaryotic cell cycle. Using the technique of RNA interference (RNAi) on the bloodstream form of Trypanosoma brucei, we were able to knock down expression of each of the 11 non-ATPase regulatory subunit proteins (Rpns) in the 19S regulatory complex of the 26S proteasome. In each case, the knock-down led to arrest of cells within the G1 and G2 phases, suggesting blockage of cell cycle progression at both G1/S and G2/M boundaries. This finding differs from that observed previously in the procyclic form of T. brucei, in which loss of individual Rpns blocks only passage across the G2/M boundary. Thus, proteasomal degradation of additional regulatory protein(s) may be required for exiting from G1 phase in the bloodstream form. In vitro differentiation of each of the 11 Rpn-depleted bloodstream form cell lines into the procyclic form was monitored. Each cell line proceeded to completion of the differentiation process like the wild-type cells with the total percentage of differentiated cells about equivalent to the sum of G1 and G2 cells. Thus, cells trapped in either G1 or G2 phase can apparently still enter and complete the process of differentiation, which is probably neither stage specific nor dependent on the progression of the T. brucei cell cycle. The process is probably a simple pattern change of gene expression in the trypanosome induced by a temperature decrease from 37 degrees C to 26 degrees C in the presence of citrate and cis-aconitate.
Yan Li; Ziyin Li; Ching C Wang
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Publication Detail:
Type:  Journal Article; Research Support, U.S. Gov't, P.H.S.    
Journal Detail:
Title:  Molecular microbiology     Volume:  49     ISSN:  0950-382X     ISO Abbreviation:  Mol. Microbiol.     Publication Date:  2003 Jul 
Date Detail:
Created Date:  2003-06-25     Completed Date:  2004-03-04     Revised Date:  2007-11-14    
Medline Journal Info:
Nlm Unique ID:  8712028     Medline TA:  Mol Microbiol     Country:  England    
Other Details:
Languages:  eng     Pagination:  251-65     Citation Subset:  IM    
Department of Pharmaceutical Chemistry, University of California, Genentech Hall, 600 16th Street, San Francisco, CA 94143-2280, USA.
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MeSH Terms
Cell Cycle / physiology*
Proteins / genetics,  metabolism
Protozoan Proteins / genetics,  metabolism
RNA Interference
RNA, Protozoan
Trypanosoma brucei brucei / cytology,  genetics,  growth & development,  physiology*
Grant Support
Reg. No./Substance:
0/Proteins; 0/Protozoan Proteins; 0/RNA, Protozoan; 0/Rpn1 protein, Trypanosoma

From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine

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