Defining the restriction point in normal asynchronous human peripheral blood lymphocytes.
Although the restriction point (R-point) was proposed in animal cells several decades ago, its existence in normal cells is still controversial, because, in most studies, long-term cultured cell lines rather than primary normal cells were used. Furthermore, cell synchronization was generally applied, resulting in growth imbalance between DNA synthesis and protein expression in cells. Finally, R-point was originally proposed as a unique arrest point that may be in G0 phase; however, generally believed R-point locates within G1 phase. Thus, up to now, there is no solid experimental evidence that supports the existence of R-point in asynchronous primary normal cells. In this study, we used freshly purified peripheral human blood lymphocytes, as asynchronous primary normal cells, to confirm the existence of restriction point in G1 not G0 phase. Our findings may help uncover the mystery of the deregulation of cell cycle progression in malignant tumors. © 2013 International Society for Advancement of Cytometry.
Department of Surgery and Molecular Medical Center, Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, 430030, People's Republic of China.
Jianwu
J
Jiang
Liang
L
Liu
Xiaolan
X
Li
Deding
D
Tao
Junbo
J
Hu
Jichao
J
Qin
D005434:Flow Cytometry / Q000379:methods*; D059585:G1 Phase Cell Cycle Checkpoints / Q000502:physiology*; D006801:Humans; D008214:Lymphocytes / Q000166:cytology*
cyclin E; flow cytometry; human peripheral blood lymphocyte; restriction point