Wang Weijia, Zhang Yang, Dettinger Philip, Reimann Andreas, Kull Tobias, Loeffler Dirk, Manz Markus G, Lengerke Claudia, Schroeder Timm
Department of Biosystems Science and Engineering, Eidgenössische Technische Hochschule (ETH) Zurich, Basel, Switzerland.
Department of Medical Oncology and Hematology, University Hospital Zurich-University of Zurich, Comprehensive Cancer Center Zurich, Zurich, Switzerland.
Blood. 2021 Sep 9;138(10):847-857. doi: 10.1182/blood.2020008386.
How hematopoietic stem cells (HSCs) integrate signals from their environment to make fate decisions remains incompletely understood. Current knowledge is based on either averages of heterogeneous populations or snapshot analyses, both missing important information about the dynamics of intracellular signaling activity. By combining fluorescent biosensors with time-lapse imaging and microfluidics, we measured the activity of the extracellular-signal-regulated kinase (ERK) pathway over time (ie, dynamics) in live single human umbilical cord blood HSCs and multipotent progenitor cells (MPPs). In single cells, ERK signaling dynamics were highly heterogeneous and depended on the cytokines, their combinations, and cell types. ERK signaling was activated by stem cell factor (SCF) and FMS-like tyrosine kinase 3 ligand in HSCs but SCF, interleukin 3, and granulocyte colony-stimulating factor in MPPs. Different cytokines and their combinations led to distinct ERK signaling dynamics frequencies, and ERK dynamics in HSCs were more transient than those in MPPs. A combination of 5 cytokines recently shown to maintain HSCs in long-term culture, had a more-than-additive effect in eliciting sustained ERK dynamics in HSCs. ERK signaling dynamics also predicted future cell fates. For example, CD45RA expression increased more in HSC daughters with intermediate than with transient or sustained ERK signaling. We demonstrate heterogeneous cytokine- and cell-type-specific ERK signaling dynamics, illustrating their relevance in regulating hematopoietic stem and progenitor (HSPC) cell fates.
造血干细胞（HSCs）如何整合来自其周围环境的信号以做出命运决定仍未完全清楚。目前的知识基于异质群体的平均值或快照分析，两者都缺少关于细胞内信号活动动态的重要信息。通过将荧光生物传感器与延时成像和微流控技术相结合，我们测量了活的单个人类脐带血造血干细胞和多能祖细胞（MPPs）中细胞外信号调节激酶（ERK）通路随时间的活性（即动态变化）。在单细胞中，ERK信号动态变化高度异质，且取决于细胞因子、它们的组合以及细胞类型。在造血干细胞中，ERK信号由干细胞因子（SCF）和FMS样酪氨酸激酶3配体激活，而在多能祖细胞中则由SCF、白细胞介素3和粒细胞集落刺激因子激活。不同的细胞因子及其组合导致不同的ERK信号动态变化频率，造血干细胞中的ERK动态变化比多能祖细胞中的更短暂。最近显示能在长期培养中维持造血干细胞的5种细胞因子的组合，在引发造血干细胞持续的ERK动态变化方面具有超相加效应。ERK信号动态变化还能预测未来的细胞命运。例如，在具有中等ERK信号而非短暂或持续ERK信号的造血干细胞子代中，CD45RA表达增加得更多。我们证明了细胞因子和细胞类型特异性的ERK信号动态变化具有异质性，说明了它们在调节造血干祖细胞（HSPC）命运中的相关性。
