p57Kip2 is expressed in quiescent mouse bone marrow side population cells.
Hematopoietic stem cells can be accurately identified by the side population (SP) phenotype. It has been previously shown that hematopoietic stem cells are cell cycle arrested, but the mechanisms involved are currently poorly understood. In the present study, results from quantitative real-time RT-PCR show that while SP cells have increased expression of various cyclins and cyclin-dependent kinases, the increased expression of cyclin-dependent kinase inhibitors, in particular p57(Kip2), is responsible for the observed cell cycle arrest. In addition, gene expression analysis of c-kit(+/)/Sca-1(+)/Lineage- SP (KSL-SP) cells demonstrates that only p57(Kip2) shows both higher expression compared to both SP and non-SP cells. Furthermore, immunostaining also demonstrates significantly higher protein expression in KSL-SP cells. These results demonstrate that the maintenance of bone marrow SP cells in G0/G1 may be carefully controlled by p57(Kip2).
Umemoto
Terumasa
T
Institute of Advanced Biomedical Engineering and Science, Tokyo Women's Medical University, Tokyo, Japan.
Yamato
Masayuki
M
Nishida
Kohji
K
Yang
Joseph
J
Tano
Yasuo
Y
Okano
Teruo
T
D000818:Animals; D001854:Bone Marrow Cells / Q000166:cytology / Q000378:metabolism*; D050761:Cyclin-Dependent Kinase Inhibitor p57; D018844:Cyclin-Dependent Kinases / Q000096:biosynthesis / Q000235:genetics; D016213:Cyclins / Q000096:biosynthesis / Q000235:genetics; D015870:Gene Expression; D051379:Mice; D008810:Mice, Inbred C57BL; D009687:Nuclear Proteins / Q000096:biosynthesis* / Q000235:genetics; D012333:RNA, Messenger / Q000378:metabolism
C493965:Cdkn1c protein, mouse; D050761:Cyclin-Dependent Kinase Inhibitor p57; D016213:Cyclins; D009687:Nuclear Proteins; D012333:RNA, Messenger; D018844:Cyclin-Dependent Kinases