Open AccessThe presence of 19‐kDa Bcl‐2 in dividing cells
Author(s) -
Hoetelmans R. W. M.,
Van de Velde C. J. H.,
Van Dierendonck J. H.
Publication year - 2003
Publication title -
cell proliferation
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.647
H-Index - 74
eISSN - 1365-2184
pISSN - 0960-7722
DOI - 10.1046/j.1365-2184.2003.00286.x
Subject(s) - nocodazole , apoptosis , microbiology and biotechnology , transfection , biology , cytoplasm , cell cycle , programmed cell death , cell nucleus , nuclear protein , nuclear transport , cleavage (geology) , cell growth , psychological repression , cell culture , cell , gene , gene expression , biochemistry , genetics , cytoskeleton , transcription factor , paleontology , fracture (geology)
. The 26‐kDa bcl‐2 gene product inhibits apoptosis and cell proliferation. Cleavage of Bcl‐2 into a 22‐kDa fragment inactivates its anti‐apoptotic activity and is a key event in apoptosis. Here, and in recent work, we describe massive 19‐kDa Bcl‐2 immunoreactivity in non‐apoptotic cells, suggesting a link with viability rather than cell death. Loss of 19 kDa Bcl‐2 in adriamycin‐induced apoptotic cells underlines this. G 2 /M‐phase accumulation of cells by nocodazole‐treatment also results in loss of 19 kDa Bcl‐2. Next to its well‐documented cytoplasmic localization, a substantial pool of Bcl‐2 resides in nuclei. Hampered nuclear localization of Bcl‐2 leads to a loss of cell cycle repression. This has led us to point at a pivotal role for nuclear Bcl‐2 in cellular proliferation. In this report, cellular fractionation of bcl‐2 transfected cells in various phases of the cell cycle reveals a constitutive cytoplasmic pool of 19 kDa Bcl‐2. Nuclear 19‐kDa Bcl‐2 immunoreactivity is far more pronounced in rapidly dividing nuclei compared with more quiescent nuclear fractions. This implicates that ongoing cell proliferation involves cleavage of nuclear Bcl‐2 with a 19‐kDa fragment.