Mechanisms of granulocyte homeostasis

 描述（由申请人提供）：了解粒细胞稳态至关重要，因为产生过少的粒细胞会导致感染风险增加（中性粒细胞减少症），而产生过多的粒细胞会导致严重的组织损伤和死亡（嗜中性粒细胞增多症、骨髓增生性疾病）。目前的知识说明了许多因素，可以修改粒细胞与单核细胞的生产，但是，我们仍然不明白一个基本的问题：哪些特定的因素控制粒细胞-单核细胞谱系的决定，在体内稳态生产？为了辨别中性粒细胞和单核细胞谱系决定之间的二元命运决定的转录网络，因为它们发生在稳态（稳态控制），我们对骨髓粒细胞-单核细胞祖细胞（GMP）进行了单细胞RNA-seq。我们的生物信息学分析揭示了一个不同的，但一致的频谱在个别鼠GMP的基因表达模式。大多数细胞可以聚集成表达粒细胞或单核细胞基因的细胞，这表明它们是为谱系确定而准备的。少数GMP表达了混合谱系模式的基因。单细胞数据的更深入分析表明，小鼠和人中粒细胞生成的关键必要因子（Gfi 1）抑制小鼠和人中单细胞生成的关键必要因子（Irf 8），这是体内粒细胞-单核细胞谱系决定的稳态控制的中心机制。我们建议确定转录程序的基础粒细胞-单核细胞谱系的命运决定在稳态，然后定义严重的先天性中性粒细胞减少症（SCN）相关的突变对转录控制的粒细胞生成在小鼠和man. We期望描绘一个跨物种的粒细胞生成的转录签名的影响，并定义血小板减少应激的影响。

 DESCRIPTION (provided by applicant): Understanding granulocyte homeostasis is crucial because producing too few granulocytes results in increased risk for infection (neutropenia), while producing too many granulocytes can result in severe tissue damage and death (neutrophilia, myeloproliferative disorders). Current knowledge illustrates many factors that can modify granulocyte versus monocyte production; however, we still do not understand a fundamental question: which specific factors control the granulocyte-monocyte lineage decision during homeostatic production in vivo? To discern the transcriptional network underlying the binary fate decision between neutrophil granulocyte and monocyte lineage decisions as they occur at steady state (homeostatic control), we have performed single-cell RNA-seq on bone-marrow granulocyte-monocyte progenitors (GMP). Our bioinformatic analyses reveal a varied, but coherent spectrum of gene expression patterns in individual murine GMPs. The majority of cells could be clustered into ones expressing either granulocytic or monocytic genes, suggesting that they were primed for lineage determination. A minority of GMPs expressed a mixed-lineage pattern of genes. Deeper analyses of the single-cell data implicate the repression of a key requisite factor for monopoiesis in mice and man (Irf8) by a key requisite factor for granulopoiesis in mice and man (Gfi1) as the central mechanism for homeostatic control of the granulocyte-monocyte lineage decision in vivo. We propose to determine the transcriptional program underlying granulocyte-monocyte lineage fate decisions during homeostasis, and then define the impact of severe congenital neutropenia (SCN)-associated mutations on transcriptional control of granulopoiesis in mice and man. We expect to delineate a cross-species transcriptional signature of granulopoiesis, and define the impact of neutropenic stress.