EMZF-1--A NOVEL GENE REQUIRED FOR EMBRYONIC HEMATOPOIESIS

哺乳动物的造血系统由不同的细胞类型组成， 执行不同的和专门的功能。这些最终 分化的细胞是短命的，从全能的细胞池形成。 假定起源于中胚层的造血干细胞（HSC） 卵黄囊血岛的细胞。虽然在这方面取得了进展， 从成人骨髓中鉴定HSC活性， 已鉴定出同质细胞群，且无遗传标记 来识别这些细胞。我们假设， 最早期的HSC将提供遗传谱系标记， 并控制原始HSC的发育 利用分子遗传学方法，我们最近发现了一个新的cDNA 使用人的9.5天血岛/卵黄囊cDNA文库克隆 髓样锌指（MZF）-1 cDNA探针。这个新鉴定的cDNA克隆， 胚外中胚层锌指蛋白-1（EM ZF-1）表达于 只存在于卵黄囊的胚外中胚层中，在胎儿中， 发育中胚胎的肝脏和心脏以及骨髓、脾脏和 成年小鼠的胸腺，表明在哺乳动物造血中的作用。这 基因位于小鼠5号染色体上，含有12个C2 H2 Kruppel样 锌指基序在两个独立的区域，这是高度同源的 MZF-1中的几个指状结构域。EMZF-1还包含一个 锌指基序下游富含丙氨酸/精氨酸的区域。等 在其他锌指基因中发现了一个结构域， 对转录调控很重要。EMZF-1基因定位于人类 7号染色体与髓细胞和淋巴细胞白血病相关。 有趣的是，PLZF，一个新发现的基因被鉴定为融合伴侣， 在变异t（11;17）易位中伴有维甲酸受体-α 与急性早幼粒细胞白血病相关，也与EMZF-1同源。 因此，EMZF-1是一个新形成的造血特异性转录因子的第三个成员。 锌指基因家族，其功能似乎是在控制 造血分化EMZF-1的功能要求 基因产物在小鼠发育早期出现， EMZF-1特异性寡核苷酸在14.5天内消除造血 胎肝和成人骨髓体外培养。最后，另一个cDNA 鉴定了对EMZF-1表现出高交叉反应性的克隆。 这个克隆LM-1D已经部分测序，并确定是一个克隆。 独立cDNA。我们建议将谱系特异性 EMZF-1的表达，鉴定其基因组结构和启动子元件 并开始分析其体内功能。EMZF-1的潜力 LM-1D克隆作为原始HSC的分子标记 将在体外和体内进行研究，并探讨其在造血中的作用 并阐明了白血病的发生。

The hematopoietic system in mammals is composed of diverse cell types that perform distinct and specialized functions. These terminally differentiated cells are short-lived, formed from a pool of totipotent hematopoietic stem cells (HSC) whose presumptive origin is the mesodermal cells of the yolk sac blood islands. Although progress has been made in the identification of HSC activity from the adult bone marrow, no such homogeneous cell population has been identified, and no genetic markers exist to identify such cells. We hypothesize that transcripts unique to the earliest HSC will provide genetic lineage markers enabling us to trace and manipulate the development of the primordial HSC. Using a molecular genetic approach we have recently identified a novel cDNA clone from a 9.5 day blood island/yolk sac cDNA library using the human myeloid zinc finger (MZF)-1 cDNAproble. This newly identified cDNA clone, extraembryonic mesoderm zinc finger-1 (EM ZF-1), was shown to be expressed exclusively in the extraembryonic mesoderm of the yolk sac, ina the fetal liver and heart of developing embryos and in the bone marrow, spleen and thymus of adult mice suggesting a role in mammalian hematopoiesis. This gene is located on mouse chromosome 5 and contains 12 C2H2 Kruppel-like zinc finger motifs in two separate regions which are highly homologous to several of the finger domains in MZF-1. EMZF-1 also contains an alanine/arginine-rich region downstream from the zinc finger motif. Such a domain has been found in other zinc finger genes and appears to be important for transcriptional regulation. The EMZF-1 gene maps to human chromosome 7 in an area associated with myeloid and lymphoid leukemias. Interestingly, PLZF, a newly discovered gene identified as a fusion partner with retinoid acid receptor-alpha in a variant t (11;17) translocation associated with acute promyelocytic leukemia, is also homologous to EMZF-1. Thus, EMZF-1 is the third member of a newly formed hematopoietic-specific zinc finger gene family whose function appears to be in the control of hematopoietic differentiation. The functional requirement for the EMZF-1 gene product appears early in mouse development since antisense oligonucleotides specific for EMZF-1 abrogates hematopoiesis in 14.5 day fetal liver and adult bone marrow cultures in vitro. Finally, another cDNA clone demonstrating high cross reactivity to the EMZF-1 was identified. This clone, LM-1D has been partially sequenced and determined to be an independent cDNA. We propose to characterize the lineage-specific expression of EMZF-1, identify its genomic structure and promoter elements and to begin the analysis of its function in vivo. The potential of EMZF-1 and the highly related LM-1D clone as molecular markers of primordial HSCs will be explored in vitro and in vivo and their function in hematopoiesis and leukemigenesis elucidated.