Hsal 2, A Novel Homeobox Gene in Hematopoiesis

描述(由申请人提供)： 这项提议的长期目标是确定Hsal2在骨髓生成中的作用。Hsal2是最近发现的一个与果蝇Sal同源框基因序列同源的发散型同源框基因。Hsal家族成员突变导致Townes-Brockes综合征伴发多器官发育缺陷。Hsal2在包括造血组织在内的大多数人体组织中都有表达。一系列证据表明Hsal2可能参与骨髓生成：(1)Hsal2的转录调控受两个独立的启动子控制，两个启动子都具有与骨髓生成关键调控基因的多个假定结合位点，包括Wilms肿瘤抑制基因(WT 1)和维甲酸受体-α(RAR)；(2)WT 1抑制Hsal2启动子的活性，而维甲酸(RA)激活荧光素酶报告基因系统中Hsal2的表达；(3)Hsal2表达与髓系承诺一致；(4)Hsal2基因缺失小鼠的髓系数量显著减少。因此，我推测细胞内的WT1/RAR-a/Hsal2途径可能在正常造血中发挥作用。在体外，Hsal2亚型在造血干细胞、髓系细胞和四环素诱导的胚胎干细胞中的过表达，以及体内Hsal2缺失小鼠的鉴定，将研究Hsal2在骨髓生成中的生物学功能。我们将继续研究Hsal2的转录调控，重点是鉴定WT1和RAR-α的结合位点。WT1和RAR-α对Hsal2表达的拮抗作用将通过WT1在髓系细胞中的过表达来进一步探讨。通过这些研究获得的知识将有助于更好地了解对正常造血至关重要的途径，并有助于开发抗击白血病的新策略。候选人李柴博士将在赞助商黛安·克劳斯博士和一个咨询委员会的指导下进行实验室研究。此外，这项提议的另一个目标是将候选人发展成为造血和白血病领域的独立和富有成效的调查员。

DESCRIPTION (provided by applicant): The long-term goal of this proposal is to define the role of Hsal2 in myelopoiesis. Hsal2 is a recently identified divergent homeobox gene that has sequence homology to the Sal homeobox gene in Drosophila. Mutations of Hsal family member lead to Townes-Brockes syndrome with multiple organ developmental defects. Hsal2 expression is present in most human tissues including hematopoietic tissues. Several lines of evidence suggest that Hsal2 may be involved in myelopoiesis: (1) The transcriptional regulation of Hsal2 is controlled by two independent promoters and both promoters bear multiple putative binding sites for regulatory genes critical for myelopoiesis, including Wilms' tumor suppression gene (WT 1) and retinoic acid receptor-alpha (RAR); (2) WT 1 represses both Hsal2 promoter activities while retinoic acid (RA) activates Hsal2 expression in a luciferase reporter gene system; (3) Hsal2 expression coincides with the myeloid lineage commitment; (4) The myeloid population in Hsal2-null mice is significant reduced. Therefore, I hypothesize that an intracellular WT 1/RAR-a/Hsal2 pathway may play a role in normal hematopoiesis. The biological function of Hsal2 in myelopoiesis will be studied by overexpression of Hsal2 isoforms in hematopoietic stem cells, myeloid cell lines, and tetracycline-inducible embryonic stem cells in vitro, and characterization of Hsal2-null mice in vivo. We will continue to characterize the transcriptional regulation of Hsal2 with a focus on identification of the binding sites of WT1 and RAR-alpha. The antagonistic effect between WT1 and RAR-alpha on Hsal2 expression will be further explored by overexpression of WT1 in myeloid cell lines. The knowledge gained by these studies will contribute to better understanding of pathways critical for normal hematopoiesis and help to develop novel strategies to combat leukemia. The candidate, Dr. Li Chai will conduct the laboratory research under the guidance of a sponsor, Dr. Diane Krause, and an advisory committee. In addition, a further objective of this proposal is to serve as a vehicle for the development of the candidate into an independent and productive investigator in the area of hematopoiesis and leukemogenesis.