A novel cell-cycle-indicator, mVenus-p27K-, identifies quiescent cells and visualizes G0-G1 transition

The quiescent (G0) phase of the cell cycle is the reversible phase from which the cells exit from the cell cycle. Due to the difficulty of defining the G0 phase, quiescent cells have not been well characterized. In this study, a fusion protein consisting of mVenus and a defective mutant of CDK inhibitor, p27 (p27K(-)) was shown to be able to identify and isolate a population of quiescent cells and to effectively visualize the G0 to G1 transition. By comparing the expression profiles of the G0 and G1 cells defined by mVenus-p27K(-), we have identified molecular features of quiescent cells. Quiescence is also an important feature of many types of stem cells, and mVenus-p27K2-transgenic mice enabled the detection of the quiescent cells with muscle stem cell markers in muscle in vivo. The mVenus-p27K(-) probe could be useful in investigating stem cells as well as quiescent cells.