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Cell. 2009 Jul 23;138(2):352-65. doi: 10.1016/j.cell.2009.04.062. Epub 2009 Jul 9.

Cyclin A is redundant in fibroblasts but essential in hematopoietic and embryonic stem cells.

Author information

1
Department of Cancer Biology, Dana-Farber Cancer Institute, Boston, MA 02115, USA.

Abstract

Cyclins are regulatory subunits of cyclin-dependent kinases. Cyclin A, the first cyclin ever cloned, is thought to be an essential component of the cell-cycle engine. Mammalian cells encode two A-type cyclins, testis-specific cyclin A1 and ubiquitously expressed cyclin A2. Here, we tested the requirement for cyclin A function using conditional knockout mice lacking both A-type cyclins. We found that acute ablation of cyclin A in fibroblasts did not affect cell proliferation, but led to prolonged expression of another cyclin, cyclin E, across the cell cycle. However, combined ablation of all A- and E-type cyclins extinguished cell division. In contrast, cyclin A function was essential for cell-cycle progression of hematopoietic and embryonic stem cells. Expression of cyclin A is particularly high in these compartments, which might render stem cells dependent on cyclin A, whereas in fibroblasts cyclins A and E play redundant roles in cell proliferation.

PMID:
19592082
PMCID:
PMC2745999
DOI:
10.1016/j.cell.2009.04.062
[Indexed for MEDLINE]
Free PMC Article

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