GATA Factor Mechanisms in Erythroid Regeneration

摘要 红细胞生成，即红细胞（RBC）的产生，经过微调以满足生理需求。期间 由于贫血引起的再生或“应激性红细胞生成”， 与红细胞生成率增加有关。理解红细胞再生的关键差距 取决于红系祖细胞中基因调控网络的激活（由转录驱动 因素）是压力特异性的，或者在其他情况下代表更广泛的控制机制。此外，底层 慢性贫血中红细胞系统失去再生能力的病因通常尚不清楚。我们 发现不育α基序结构域-14（Samd 14）基因在急性/慢性贫血模型中升高。 Samd 14受转录因子GATA 2调节，GATA 2协调一个基因网络， 在造血和血液病中的作用。GATA 2占据的Samd 14顺式元件（Samd 14-Enh） 是溶血性贫血模型中存活所必需的，但对于稳态红细胞生成是必需的。红系 缺乏Samd 14-Enh的祖细胞具有受损的c-Kit信号传导，c-Kit信号传导是一种典型的调节细胞凋亡的途径。 造血和红细胞生成。这些结果揭示了GATA 2-Samd 14-c-Kit调节蛋白的参与。 轴在红细胞再生中的作用。而含有SAM结构域的蛋白质参与造血和细胞增殖， 尽管在贫血症中有几种蛋白质被上调，但它们的作用机制尚不清楚。我们的数据 提示具有模拟Samd 14-Enh特性的增强子的另外的群组是贫血调节的。我们 假设Samd 14和另外GATA 2和再生激活（G2 R）增强子控制红细胞 再生在目标1中，人和小鼠中的机制分析将定义细胞对Samd 14的要求。 信号传导和红系祖细胞的存活。目的2：克隆GATA 2和贫血调节基因（G2 R） 控制着围绕贫血反应的复杂生物学的一部分。使用初级 人/小鼠细胞和创新的小鼠遗传模型方法将测试SAMD 14机制（以及其他 SAM结构域蛋白）在c-Kit信号传导和红细胞再生中的作用。这些目标将建立有价值的对比 稳态和再生红细胞生成机制之间的关系，增强子敲除和基因敲除 表型，以及含有相似序列和分子的功能不同的顺式元件之间的差异。 特性.通过阐明急性贫血中的GATA 2-Samd 14-c-Kit轴，以及全局/基因座特异性GATA 2 Samd 14-Enh样顺式元件的机制，我们希望这些研究将揭示基本的基因调控 红细胞再生机制与血液病，包括贫血的影响。

ABSTRACT Erythropoiesis, the production of red blood cells (RBCs), is fine-tuned to meet physiological demands. During regeneration or “stress erythropoiesis” caused by anemia, a subset of genes and proteins are upregulated in association with an increased rate of RBC production. A critical gap in understanding erythroid regeneration hinges on whether the activation of gene regulatory networks in erythroid progenitors (driven by transcription factors) are stress-specific or represent broader control mechanisms in other contexts. Moreover, the underlying etiologies in which the erythroid system loses its ability to regenerate in chronic anemias are often unclear. We discovered that the Sterile Alpha Motif Domain-14 (Samd14) gene is elevated in models of acute/chronic anemia. Samd14 is regulated by the transcription factor GATA2, which coordinates a network of genes with critical functions in hematopoiesis and hematologic disease. The GATA2-occupied Samd14 cis-element (Samd14-Enh) is required for survival in a model of hemolytic anemia, but dispensable for steady state erythropoiesis. Erythroid progenitors lacking Samd14-Enh have impaired c-Kit signaling, a quintessential pathway regulating hematopoiesis and erythropoiesis. These results reveal the involvement of a GATA2-Samd14-c-Kit regulatory axis in erythroid regeneration. Whereas SAM domain-containing proteins are involved in hematopoiesis and cell signaling, and several are upregulated in anemia, their mechanisms of action are not well understood. Our data suggests additional cohorts of enhancers with properties mimicking the Samd14-Enh are anemia-regulated. We hypothesize that Samd14 and additional GATA2 and Regeneration-Activated (G2R) enhancers control erythroid regeneration. In Aim 1, mechanistic analyses in human and mouse will define Samd14 requirements for cell signaling and survival of erythroid progenitors. Aim 2 will delineate a GATA2 and anemia-regulated (G2R) gene network governing a sector of the complex biology surrounding anemia responses. Approaches using primary human/mouse cells and innovative mouse genetic model approaches will test SAMD14 mechanisms (and other SAM domain proteins) in c-Kit signaling and erythroid regeneration. These aims will establish valuable contrasts between homeostatic and regenerative erythropoietic mechanisms, enhancer knockout and gene knockout phenotypes, and between functionally-distinct cis-elements which contain similar sequence and molecular properties. By elucidating a GATA2-Samd14-c-Kit axis in acute anemia, and global/locus-specific GATA2 mechanisms of Samd14-Enh-like cis-elements, we expect these studies will reveal fundamental gene regulatory mechanisms in erythroid regeneration with implications in hematologic disease, including anemias.