%0 Journal Article
%T New clues to understand how CENP-A maintains centromere identity
%A Patricia S¨˘nchez
%A Ana Losada
%J Cell Division
%D 2011
%I BioMed Central
%R 10.1186/1747-1028-6-11
%X Active centromeres are defined by the presence of nucleosomes containing a unique histone H3 variant known as CENP-A [1,2]. Stretched centromeric chromatin from Drosophila, human and chicken DT40 cells shows the presence of interspersed blocks of CENP-A and canonical H3 nucleosomes [3,4]. This chromatin fiber must then be folded to adopt the appropriate compact conformation over which the kinetochore is assembled [5,6]. In proliferating cells, the amount of CENP-A present at centromeres has to be replenished at the time or after centromeric DNA is duplicated in order to propagate centromere identity. The mechanisms responsible for de novo CENP-A deposition specifically at centromeres and their regulation in the cell cycle have been an active field of research over the last years. Despite the lack of conservation of centromeric DNA sequences and of the timing of CENP-A nucleosome assembly among different organisms, there is a remarkable conservation of the major players involved in centromere propagation. Thus, research in different experimental systems greatly contributes to put the big picture in focus.One central question of centromere biology is how is CENP-A deposited at centromeric chromatin. Members of a protein family named Scm3/HJURP (Holliday Junction Recognizing Protein), conserved from yeast to humans, have been proposed to act as CENP-A specific chaperones in yeast and human cells [7-15]. These proteins interact physically with CENP-A, can be found at centromeres and, most importantly, are required for CENP-A loading and maintenance. Many additional factors play a role in CENP-A incorporation, but how it actually happens remains unclear. To address this issue, we developed an assay to measure CENP-A incorporation using the Xenopus egg cell-free system [16]. In this immunofluorescence-based assay, nuclei assembled from sperm chromatin and taken at two different time points (e.g. mitosis and subsequent interphase) are combined and processed for immunofluor
%U http://www.celldiv.com/content/6/1/11