Fig. 2

Simulations of system dynamics with respect to Maff expression. a-c Stable equilibriums (steady states) of Cyc D*, Cyc E* and E2F with respect to the expression level of Maff are shown in (a), (b) and (c) respectively. As known, the three molecules are benchmarks for the transitions of G0 - > G1/G1 - > S in cell cycle and their levels directly correspond to the speeds that cells proceed through the transition checkpoints. The data curves consist of the steady state concentrations of the molecules under various genetic synthesis rates (k _s _maff, i.e. expression level) of Maff. As shown herein, steady states of Cyc D* a and E2F c have increased as k _s _maff rises, indicating that G0 - > G1 is accelerated upon high expression of Maff. In addition, Cyc E* b is maintained at a level that is capable of driving G1 - > S. Cyc D/E* means the activated forms of Cyclin D/E (i.e. being bound with their corresponding Cdks). Metric units of x- and y- axes are “moles/cell/min” and “moles/cell”. d Proliferation of HSCs over-expressing (i.e. transducted with) Maff is shown herein; “Vector” means cell transducted with an empty vector (i.e. control data). As shown, the proliferation capability of HSCs with high expression of Maff is significantly larger (p-value <0.005 compared with control). e Ratio of HSCs staying in G0 phase before (control) and after Maff transduction (over-expression). Cells in different cycling status are sorted using flow cytometry according to Ki67 and Hoechst 33,342 staining. Data show that the ratio of G0 HSCs is significently lowered when Maff is highly expressed (p-value <0.05), indicating that high Maff expression mobilizes HSCs to escape the G0 phase, thus more HSCs enter the later cycling phase(s)