生命学院学术报告

Title: Adaptive control of quiescent stem cells

Speaker: Rui Yi, Ph.D.

Associate Professor

Molecular, Cellular and Developmental Biology, University of Colorado Boulder, USA

Time: 2015年08月10日（周一）14:00 -15: 30

Place: 金光大楼411会议室

Host: 宋艳（62752120）

Abstract

Maintenance of adult stem cells (SCs) is critical for tissue homeostasis and wound repair throughout an organism’s lifespan. Adult tissues use multiple strategies to maintain a constant pool of SCs. Self-renewal, a defining property of SCs, is achieved by either symmetrical or asymmetrical cell division, through which new generations of SCs are produced to replenish the SC pool. Some SCs can also be kept in a quiescent state for a prolonged period of time to minimize cell turnover. In many mammalian tissues, notably hair follicles (HFs), blood, and muscle, adult SCs acquire quiescence and infrequently divide for self-renewal. Mechanisms that govern quiescence and self-renewal in these model systems have been investigated extensively. However, a critical issue remains largely unexplored: how do quiescent SCs cope with an ever-changing demand between maintaining SC identity and self-renewal through cell division? Because quiescent SCs are usually activated by signals from the SC niche, it is generally surmised that activated SCs return to quiescence and properly resume their identity when activating signals wane. It is unknown for quiescent SCs whether the process of self-renewal and cell cycle reentry induces a significant change to the cellular state and how dividing SCs return to quiescence. In this study, we investigate largely synchronized HFSC populations existing during early adulthood in mice to probe this unknown layer of regulation. Integrating genetic and molecular analyses for transcription factors (TFs), as well as mathematical modeling of HFSC cellular states using mRNA profiling data, we reveal that activated HFSCs reside in a distinct cellular state from either their quiescent counterparts or the committed hair germ (HG) progenitors. Furthermore, adaptive expression of a specific TF in the activated HFSCs is required to reinforce the quiescent cellular state and maintain the SC identity. These findings illustrate an unexpectedly dynamic response by quiescent SCs to self-renewal and provide new possibilities for examining SC maintenance in both normal and pathological conditions.

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