Cyclin A Is Redundant in Fibroblasts but Essential in Hematopoietic and Embryonic Stem Cells

Ilona Kalaszczynska, Yan Geng, Tadafumi Iino, Shin ichi Mizuno, Yoon Choi, Ilona Kondratiuk, Daniel P. Silver, Debra J. Wolgemuth, Koichi Akashi, Piotr Sicinski

Research output: Contribution to journalArticlepeer-review

170 Citations (Scopus)


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.

Original languageEnglish
Pages (from-to)352-365
Number of pages14
Issue number2
Publication statusPublished - Jul 23 2009
Externally publishedYes

All Science Journal Classification (ASJC) codes

  • Biochemistry, Genetics and Molecular Biology(all)


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