Published online 15 December 2004
Nucleic Acids Research, Vol. 32 No. 22 © Oxford University Press 2004; all rights reserved
Telomere length regulation and transcriptional silencing in KU80-deficient Trypanosoma brucei
Laboratory of Molecular Parasitology, The Rockefeller University, Box 185, 1230 York Avenue, New York, NY 10021-6399, USA
* To whom correspondence should be addressed. Tel: +1 212 327 7571; Fax: +1 212 327 7845; Email: george.cross{at}rockefeller.edu
The authors wish it to be known that, in their opinion, the first two authors should be regarded as joint First Authors
Received September 8, 2004; Revised October 26, 2004; Accepted November 22, 2004
KU is a heterodimer, consisting of 
70 and 80 kDa subunits (KU70 and KU80, respectively), which is involved in a variety of nuclear functions. We generated tbKU80-deficient trypanosomes to explore the potential role of the tbKU complex in telomere maintenance and transcriptional regulation of variant surface glycoprotein (VSG) genes in Trypanosoma brucei. Using real-time PCR, we demonstrated that the expression of several different VSG genes remains tightly regulated in tbKU80-deficient bloodstream-form cell lines, suggesting that VSG transcription profiles do not change in these cells. Owing to developmental silencing of the VSG Expression Sites (ES), no VSG is transcribed in the insect procyclic stage. With a green fluorescent protein reporter system, we showed that tbKU80-deficient mutants are fully capable of ES silencing after differentiation into procyclic forms. Using T7 RNA polymerase to explore the transcriptional accessibility of ES chromatin in vivo, we demonstrated that tbKU80-deficient bloodstream-form cells were able to generate transcriptionally repressed ES chromatin after differentiation into procyclic cells. Finally, we demonstrated progressive telomere shortening in tbKU80-deficient mutants. The possible function of tbKU80 in telomere maintenance and regulation of telomerase is discussed.
CiteULike 
Connotea 
Del.icio.us What's this?
This article has been cited by other articles:
|
|
 |
|
  P. Burton, D. J. McBride, J. M. Wilkes, J. D. Barry, and R. McCulloch Ku Heterodimer-Independent End Joining in Trypanosoma brucei Cell Extracts Relies upon Sequence Microhomology Eukaryot. Cell, October 1, 2007; 6(10): 1773 - 1781. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 L. Glover, S. Alsford, C. Beattie, and D. Horn Deletion of a trypanosome telomere leads to loss of silencing and progressive loss of terminal DNA in the absence of cell cycle arrest Nucleic Acids Res., February 16, 2007; 35(3): 872 - 880. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 D. Landeira and M. Navarro Nuclear repositioning of the VSG promoter during developmental silencing in Trypanosoma brucei J. Cell Biol., January 16, 2007; 176(2): 133 - 139. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 B. Li, A. Espinal, and G. A. M. Cross Trypanosome Telomeres Are Protected by a Homologue of Mammalian TRF2 Mol. Cell. Biol., June 15, 2005; 25(12): 5011 - 5021. [Abstract] [Full Text] [PDF]
|
|