Department of Genetics, Development and Cell Biology, Iowa State University, Ames, IA.
Section of Cell and Developmental Biology, University of California at San Diego, San Diego, CA.
Blood Adv. 2021 Feb 9;5(3):796-811. doi: 10.1182/bloodadvances.2020003096.
Granulin is a pleiotropic protein involved in inflammation, wound healing, neurodegenerative disease, and tumorigenesis. These roles in human health have prompted research efforts to use granulin to treat rheumatoid arthritis and frontotemporal dementia and to enhance wound healing. But how granulin contributes to each of these diverse biological functions remains largely unknown. Here, we have uncovered a new role for granulin during myeloid cell differentiation. We have taken advantage of the tissue-specific segregation of the zebrafish granulin paralogues to assess the functional role of granulin in hematopoiesis without perturbing other tissues. By using our zebrafish model of granulin deficiency, we revealed that during normal and emergency myelopoiesis, myeloid progenitors are unable to terminally differentiate into neutrophils and macrophages in the absence of granulin a (grna), failing to express the myeloid-specific genes cebpa, rgs2, lyz, mpx, mpeg1, mfap4, and apoeb. Functionally, macrophages fail to recruit to the wound, resulting in abnormal healing. Our CUT&RUN experiments identify Pu.1, which together with Irf8, positively regulates grna expression. In vivo imaging and RNA sequencing experiments show that grna inhibits the expression of gata1, leading to the repression of the erythroid program. Importantly, we demonstrated functional conservation between the mammalian granulin and the zebrafish ortholog grna. Our findings uncover a previously unrecognized role for granulin during myeloid cell differentiation, which opens a new field of study that can potentially have an impact on different aspects of human health and expand the therapeutic options for treating myeloid disorders such as neutropenia or myeloid leukemia.
颗粒蛋白是一种多功能蛋白，参与炎症、伤口愈合、神经退行性疾病和肿瘤发生。这些在人类健康中的作用促使研究人员努力利用颗粒蛋白治疗类风湿性关节炎和额颞叶痴呆，并促进伤口愈合。但是，颗粒蛋白如何促进这些不同的生物学功能仍知之甚少。在这里，我们在髓样细胞分化过程中发现了颗粒蛋白的一个新角色。我们利用斑马鱼颗粒蛋白同源物的组织特异性分离，评估了颗粒蛋白在造血过程中的功能作用，而不会干扰其他组织。通过使用我们的颗粒蛋白缺陷斑马鱼模型，我们揭示了在正常和应急髓样生成过程中，髓样祖细胞在缺乏颗粒蛋白 a (grna) 的情况下无法终末分化为中性粒细胞和巨噬细胞，无法表达髓样特异性基因 cebpa、rgs2、lyz、mpx、mpeg1、mfap4 和 apoeb。功能上，巨噬细胞无法招募到伤口，导致愈合异常。我们的 CUT&RUN 实验鉴定了 Pu.1，它与 Irf8 一起正向调节 grna 的表达。体内成像和 RNA 测序实验表明，grna 抑制了 gata1 的表达，从而抑制了红细胞程序。重要的是，我们证明了哺乳动物颗粒蛋白和斑马鱼同源物 grna 之间的功能保守性。我们的研究结果揭示了颗粒蛋白在髓样细胞分化过程中以前未被认识到的作用，这开辟了一个新的研究领域，有可能对人类健康的不同方面产生影响，并扩大治疗髓样疾病（如中性粒细胞减少症或髓样白血病）的治疗选择。
