[Relationship between CENP-B gene expression and the cell cycle].
The centromere/kinetochore is a specialized structure at the primary constriction of mammalian chromosomes. It participates in and is necessary for the mitotic chromosome movement. Centromere Protein B(CENP-B) is a highly conserved protein located at the centromere/kinetochore region. In this article, we explore the relationship between CENP-B expression and cell proliferation. HeLa cells were synchronized at different phases of the cell cycle and the synchronized cells were examined by flow cytometry and 3H-TdR labelling. ACA immunostaining showed the discrete single spots in nuclei of the cells at G1 and S phase, and spots in pairs mostly in those at G2 phase. Dot blot and Northern blot indicated that CENP-B gene was expressed at all phases of the cell cycle, but the expression level very much different with the highest at G2 phase and the lowest at S phase. Interestingly relatively high expression of CENP-B gene was also found in M phase, showing the continuity of the CENP-B gene expression during the cell cycle. This continuity implies a possibility that the assembly of the new centromere/kinetochore can not occur until centromere proteins reach a critical concentration when cells enter S phase and G 2 phase. Also, the continuous expression of centromere proteins may be necessary for the centromere/kinetochore function. In addition, the relationship between CENP-B gene expression and the nuclear skeleton was investigated. The nuclear skeleton-associated DNA extracted after Bam HI digestion were hybridized with 32P-labelled cDNA of CENP-B gene by means of Southern blot technique. The results that there stronger positive hybridization reaction in G 2 phase than in S phase indicated that CENP-B gene was more closely associated with the nuclear skeleton in G 2 phase cells than in S phase cells, which was in consistence with the level of the CENP-B gene expression at G 2 and S phase cells.
Zhang
H X
HX
Key Lab of Cell Proliferation and Regulation Biology, Beijing Normal University.
Chen
D G
DG
Peng
A
A
Wang
Y C
YC
D001324:Autoantigens / Q000096:biosynthesis; D002453:Cell Cycle; D002503:Centromere / Q000378:metabolism*; D051936:Centromere Protein B; D002868:Chromosomal Proteins, Non-Histone / Q000096:biosynthesis / Q000235:genetics*; D004268:DNA-Binding Proteins; D015870:Gene Expression; D006367:HeLa Cells / Q000166:cytology; D006801:Humans
D001324:Autoantigens; C497926:CENPB protein, human; D051936:Centromere Protein B; D002868:Chromosomal Proteins, Non-Histone; D004268:DNA-Binding Proteins