The appearance of truncated cyclin A2 correlates with differentiation of mouse embryonic stem cells.
The presence of a form of cyclin A2 with an N-terminal truncation has recently been reported in various murine cell lines and tissues. The truncated cyclin A2 binds to and activates the cyclin-dependent kinase 2 (CDK2). However, CDK2 bound by the truncated cyclin A2 is located in the cytoplasm in contrast to CDK2 bound to full-length cyclin A2, which is in the nucleus. Here, we show that proliferating mouse embryonic stem cells (ES cells) contain very little truncated cyclin A2 but as the cells are induced to differentiate the amount of truncated cyclin A2 increases. The expression pattern of truncated cyclin A2 was the same in p27(Kip1) -/- differentiating ES cells as in the differentiating wild-type cells. We conclude that p27(Kip1) is not necessary for the proteolytic cleavage that gives rise to the truncated form of cyclin A2 in differentiating ES cells and that this post-translational modification is not a function of the cell density but is correlated with differentiation.
Anger
Martin
M
Department of Biology, University of Pennsylvania, USA.
Bryja
Vitezslav
V
Jirmanova
Ludmila
L
Hampl
Ales
A
Carrington
Mark
M
Motlik
Jan
J
Dvorak
Petr
P
Kubelka
Michal
M
D000818:Animals; D018797:Cell Cycle Proteins / Q000235:genetics / Q000378:metabolism; D002454:Cell Differentiation / Q000502:physiology*; D002460:Cell Line; D019925:Cyclin A / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D050760:Cyclin-Dependent Kinase Inhibitor p27; D004622:Embryo, Mammalian; D006131:Growth Inhibitors / Q000494:pharmacology; D015850:Interleukin-6; D053605:Leukemia Inhibitory Factor; D008222:Lymphokines / Q000494:pharmacology; D051379:Mice; D000071137:Poly (ADP-Ribose) Polymerase-1; D011065:Poly(ADP-ribose) Polymerases; D011506:Proteins / Q000378:metabolism; D013234:Stem Cells / Q000166:cytology / Q000187:drug effects / Q000502:physiology*; D014212:Tretinoin / Q000494:pharmacology; D025521:Tumor Suppressor Proteins / Q000235:genetics / Q000378:metabolism
C493961:Cdkn1b protein, mouse; D018797:Cell Cycle Proteins; D019925:Cyclin A; D006131:Growth Inhibitors; D015850:Interleukin-6; D053605:Leukemia Inhibitory Factor; C507838:Lif protein, mouse; D008222:Lymphokines; D011506:Proteins; D025521:Tumor Suppressor Proteins; D050760:Cyclin-Dependent Kinase Inhibitor p27; D014212:Tretinoin; C499321:Parp1 protein, mouse; D000071137:Poly (ADP-Ribose) Polymerase-1; D011065:Poly(ADP-ribose) Polymerases