Regulation of Hoxa1 Gene Expression in Mouse Embryonic Stem Cells

 描述(申请人提供)：HoxA1基因在小鼠胚胎干细胞中的表达调控同源异型盒(HOX)转录因子家族包括胚胎模式和器官发生的重要调节因子。在小鼠中，HOX家族成员HoxA1的两个等位基因的失活会导致许多发育缺陷，包括后脑缺陷和异常的头骨骨化，最终导致新生儿死亡。这些观察结果强调了该基因在早期大脑和神经脊派生结构的正常发育中的重要性。在人类中，该基因的突变被描述为与各种中枢神经系统(CNS)疾病相关，其过度表达与癌症的发展有关。因此，严格控制HoxA1基因的表达对于正常的细胞功能和胚胎发育是必要的。虽然HoxA1在胚胎发育过程中的相关性已被认识到20多年，但对调节这一重要转铁蛋白表达的因素知之甚少。在这项工作中，我们提供了初步的数据，表明维甲酸受体β2(RARb2)作为HoxA1基因表达的负调控因子在小鼠胚胎干细胞(ES)中发挥作用。此外，我们对HoxA1进行了芯片上的分析，并在HoxA1编码区确定了一个可能的HoxA1结合位点，这表明该TF存在一种新的自动调节机制。因此，这些初步结果构成了本项目提出的具体目标的基础。特定目的1将在转录水平上研究HoxA1基因的表达调控。具体目标2将调查各种因素的影响 在转录后水平上调节HoxA1的表达。HoxA1基因调控反馈环的机制将在特定的目标3中进行研究。综上所述，本研究的目的是阐明HoxA1在小鼠ES细胞中表达的分子机制。这些研究的结果将与发育生物学、器官和组织替代以及癌症研究等领域相关。

 DESCRIPTION (provided by applicant): Regulation of Hoxa1 Gene Expression in Mouse Embryonic Stem Cells The homeobox (Hox) family of transcription factors comprises important regulators of embryonic patterning and organogenesis. Inactivation in mice of both alleles of the Hoxa1, a Hox family member, results in numerous developmental defects, including hindbrain deficiencies and abnormal skull ossification, and ultimately, in neonatal death. These observations emphasize the importance of this gene in the proper development of the early brain and neural crest- derived structures. In humans, mutations in this gene have been described in association with various Central Nervous System (CNS) disorders and its overexpression has been associated with cancer development. Thus, a strict control of Hoxa1 gene expression is required for proper cellular function and embryonic development. Although the relevance of Hoxa1 during embryonic development has been recognized for over two decades, little is known about the factors that regulate the expression of this important TF. In this work, we present preliminary data that suggests a role for the retinoic acid receptor beta 2 (RARb2) as a negative regulator of Hoxa1 gene expression in mouse Embryonic Stem (ES) cells. Furthermore, we have performed ChIP-on-chip analyses for Hoxa1 and identified a putative Hoxa1 binding site in the Hoxa1 coding region, which suggests the presence of a novel autoregulatory mechanism for this TF. Thus, these preliminary results form the basis of the specific aims proposed in this project. Specific Aim 1 will investigate the regulation of Hoxa1 gene expression at the transcriptional level. Specific Aim 2 will investigate the effect of factors that regulate Hoxa1 expression at the posttranscriptional level. The mechanism of Hoxa1 feedback loop of gene regulation will be investigated in Specific Aim 3. In summary, the goal of the proposed study is to shed light on the molecular mechanism by which the expression of Hoxa1 is regulated in mouse ES cells. The results from these studies will be of relevance to the areas of Developmental Biology, Organ and Tissue Replacement, and Cancer Research, among others.