Identification of centromeric antigens in dicentric Robertsonian translocations: CENP-C and CENP-E are necessary components of functional centromeres

Abstract

Robertsonian translocations are the most common structural dicentric rearrangements in humans. The stability of these dicentrics is attributed to the inactivation of one centromere by mechanisms which are currently unknown. The presence and amounts of centromeric proteins (CENPs) differ between the centromeres of the few dicentrics which have been studied, providing a limited understanding of the protein components necessary for centromeric function. However, CENP-C previously has been observed only at the active centromeres in two dicentric chromosomes. In the present investigation, the presence and localizations of several centromeric antigens, CENP-B, -C and -E, have been determined in 12 dicentric Robertsonian translocations. Each translocation was studied initially using in situ hybridization with alpha-satellite DNA probes to determine the active centromere. Subsequent immunofluorescence of monoclonal and polyclonal antibodies generated to various centromeric antigens demonstrated that the protein composition differs at the two centromeres of these dicentric translocations. While CENP-B was present at both active and inactive centromeres, CENP-C and -E were located at active centromeres only in the majority of translocations. These results confirm previous observations of CENP-C at active centromeres and provide the first evidence that CENP-E correlates with active centromeres as well, demonstrating that at least two specific centromeric proteins are required for human centromeric function.

Epigenetic engineering: histone H3K9 acetylation is compatible with kinetochore structure and function

“…Independent of this sequence preference, specific deposition of the centromeric histone H3 variant CENP-A (Earnshaw and Rothfield, 1985) is thought to form the basis for an 'epigenetic' maintenance of centromere identity (Allshire and Karpen, 2008;Okamoto et al, 2007;Vafa and Sullivan, 1997;Warburton et al, 1997). The epigenetic control of centromere activity is strikingly illustrated by the inactivation of centromeres on dicentric chromosomes (Earnshaw and Migeon, 1985;Earnshaw et al, 1989;Merry et al, 1985;Sugata et al, 2000;Sullivan and Schwartz, 1995) and by rare neocentromeres that recruit CENP-A and assemble fully functional kinetochore structures on non-alphoid DNA (Alonso et al, 2007;Depinet et al, 1997;du Sart et al, 1997;Saffery et al, 2000;Warburton et al, 1997).…”

Euchromatic Subdomains in Rice Centromeres Are Associated with Genes and Transcription

“…Centromeric (CEN) chromatin is marked by a centromere-specific histone variant, CENH3 (known as CENP-A in mammals and CID in Drosophila melanogaster) (Henikoff et al, 2001). Centromeres can be inactivated or activated in a noncentromeric genomic region without changing the underlying sequences (Sullivan and Schwartz, 1995;Han et al, 2006;Marshall et al, 2008b;Zhang et al, 2010). Thus, the establishment and maintenance of centromeres is not defined by the underlying DNA sequences but is determined by poorly understood epigenetic mechanisms (Allshire and Karpen, 2008).…”

Chromosome engineering: prospects for gene therapy

“…Both of these types of ectopic alpha satellite DNA cell lines have lent considerable insight into the role of alpha satellite DNA in centromere formation and requirements for additional proteins and chromatin modifications associated with active centromeres. [23][24][25] One exciting avenue of research involves attempts to manipulate and reactivate such regions of nonfunctional alpha satellite DNA.…”