Bcl-2 is an integral component of mitotic chromosomes.
We previously demonstrated that phospho-Thr56 Bcl-2 colocalizes with Ki-67 and nucleolin in nuclear structures in prophase cells and is detected on mitotic chromosomes in later mitotic phases. To gain insight into the fine localization of Bcl-2 on mitotic chromosomes, we further investigated Bcl-2 localization by immunostaining of Bcl-2 with known components of metaphase chromosomes and electron microscopic immunocytochemistry. Immunofluorescence analysis on HeLa mitotic cells together with chromatin immunoprecipitation assays showed that Bcl-2 is associated with the condensed chromatin. Co-immunostaining experiments performed on mitotic chromosome spreads demonstrated that Bcl-2 is not localized on the longitudinal axis of chromatids with the condensin complex, but partially colocalizes with histone H3 on some regions of the mitotic chromosome. Finally, most of the Bcl-2 staining overlaps with Ki-67 staining at the chromosome periphery. Bcl-2 localization at the periphery and over the mitotic chromosome was confirmed by immunoelectron microscopy on mitotic cells. Our results indicate that Bcl-2 is an integral component of the mitotic chromosome.
Barboule
Nadia
N
Université de Toulouse, LBCMCP, 118 route de Narbonne, Toulouse, France. barboule@cict.fr
Demeter
Katalin
K
Benmeradi
Nacer
N
Larminat
Florence
F
D002843:Chromatin / Q000378:metabolism; D002868:Chromosomal Proteins, Non-Histone / Q000378:metabolism; D002877:Chromosomes, Human / Q000378:metabolism* / Q000648:ultrastructure; D006367:HeLa Cells; D006657:Histones / Q000378:metabolism; D006801:Humans; D007150:Immunohistochemistry; D019394:Ki-67 Antigen / Q000378:metabolism; D008938:Mitosis / Q000502:physiology*; D019253:Proto-Oncogene Proteins c-bcl-2 / Q000235:genetics / Q000378:metabolism*
D002843:Chromatin; D002868:Chromosomal Proteins, Non-Histone; D006657:Histones; D019394:Ki-67 Antigen; D019253:Proto-Oncogene Proteins c-bcl-2