Association of pKi-67 with satellite DNA of the human genome in early G1 cells.
pKi-67 is a nucleolar antigen that provides a specific marker for proliferating cells. It has been shown previously that pKi-67's distribution varies in a cell cycle-dependent manner: it coats all chromosomes during mitosis, accumulates in nuclear foci during G1 phase (type I distribution) and localizes within nucleoli in late G1 S and G2 phase (type II distribution). Although no function has as yet been ascribed to pKi-67, it has been found associated with centromeres in G1. In the present study the distribution pattern of pKi-67 during G1 in human dermal fibroblasts (HDFs) was analysed in more detail. Synchronization experiments show that in very early G1 cells pKi-67 coincides with virtually all satellite regions analysed, i.e. with centromeric (alpha-satellite), telomeric (minisatellite) and heterochromatic blocks (satellite III) on chromosomes 1 and Y (type Ia distribution). In contrast, later in the G1 phase, a smaller fraction of satellite DNA regions are found collocalized with pKi-67 foci (type Ib distribution). When all pKi-67 becomes localized within nucleoli, even fewer satellite regions remain associated with the pKi-67 staining. However, all centromeric and short arm regions of the acrocentric chromosomes, which are in very close proximity to or even contain the rRNA genes, are collocalized with anti-pKi-67 staining throughout the remaining interphase of the cell cycle. Thus, our data demonstrate that during post-mitotic reformation and nucleogenesis there is a progressive decline in the fraction of specific satellite regions of DNA that remain associated with pKi-67. This may be relevant to nucleolar reformation following mitosis.
Bridger
J M
JM
Organization of Complex Genomes, Deutsches Krebsforschungzentrum, Heidelberg, Germany.
Kill
I R
IR
Lichter
P
P
D002466:Cell Nucleolus / Q000737:chemistry; D002478:Cells, Cultured; D002843:Chromatin / Q000737:chemistry; D002878:Chromosomes, Human, Pair 1 / Q000737:chemistry; D004276:DNA, Satellite / Q000032:analysis*; D005347:Fibroblasts; D019084:Fluorescent Antibody Technique, Indirect; D016193:G1 Phase / Q000502:physiology*; D015894:Genome, Human; D006801:Humans; D017404:In Situ Hybridization, Fluorescence / Q000379:methods; D007399:Interphase; D019394:Ki-67 Antigen / Q000032:analysis*; D012867:Skin / Q000166:cytology; D014998:Y Chromosome / Q000737:chemistry
D002843:Chromatin; D004276:DNA, Satellite; D019394:Ki-67 Antigen