REGULATION OF MOUSE ES CELL DIFFERENTIATION INTO NEURONS BY HOXA1

这个子项目是许多利用资源的研究子项目之一 由NIH/NCRR资助的中心拨款提供。子项目的主要支持 而子项目的主要调查员可能是由其他来源提供的， 包括其它NIH来源。 列出的子项目总成本可能 代表子项目使用的中心基础设施的估计数量， 而不是由NCRR赠款提供给子项目或子项目工作人员的直接资金。 该项目的长期目标是阐明和表征Hoxa 1转录因子指导胚胎干细胞分化为神经元的分子机制。Hoxa 1基因在细胞和组织中的表达可以被维生素A的衍生物视黄酸（RA）激活。在小鼠中，Hoxa 1基因的两个等位基因的失活导致许多发育缺陷，包括后脑缺陷和异常颅骨骨化，并最终导致新生儿死亡。在人类中，HOXA 1基因的截短突变与自闭症易感性有关。本研究旨在探讨Hoxa 1在RA诱导小鼠胚胎干细胞分化为胚状体过程中的作用。由于RA是Hoxa 1基因表达的直接诱导剂，也是ES细胞分化的诱导剂，我们假设Hoxa 1的作用是通过抑制内胚层和/或中胚层细胞谱系来促进神经元细胞分化。我们还推测，特异性激活RARb可能会导致内胚层分化和抑制小鼠ES细胞的神经发生。为了验证这一假设，我们首先通过采用抗体微阵列检测了RARb 2激动剂AC 55649对蛋白质表达的影响。作为RARb 2处理的结果，我们观察到用阵列检查的约40种（共224种）蛋白质增加了2倍或更多，其中大多数在Pathway Architect检查后被发现与Ap 1/c-Jun途径相关。从这些研究中获得的结果可能会导致新的分化策略的同质细胞群的培养一代。

This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. Primary support for the subproject and the subproject's principal investigator may have been provided by other sources, including other NIH sources. The Total Cost listed for the subproject likely represents the estimated amount of Center infrastructure utilized by the subproject, not direct funding provided by the NCRR grant to the subproject or subproject staff. The long-term goal of this project is to elucidate and characterize the molecular mechanism by which the Hoxa1 transcription factor directs the differentiation of embryonic stem cells into neurons. Expression of the Hoxa1 gene in cells and tissues can be activated by retinoic acid (RA), a derivative of vitamin A. Inactivation of both alleles of the Hoxa1 gene in mice results in numerous developmental defects, including hindbrain deficiencies and abnormal skull ossification, and ultimately, in neonatal death. In humans, truncating mutations of the HOXA1 gene have been associated to autism susceptibility. This project will characterize the function of Hoxa1 during the RA-induced differentiation of mouse embryonic stem (ES) cells grown in suspension as embryoid bodies (EBs). Because RA is a direct inducer of Hoxa1 gene expression and is also an inducer of ES cell differentiation, we hypothesize that the role of Hoxa1 is to promote neuronal cell differentiation by repressing endodermal and/or mesodermal cell lineages. We also hypothesize that the specific activation of RARb may lead to endodermal differentiation and repression of neurogenesis in mouse ES cells. To test this hypothesis, we first examined the effect of the RARb2 agonist AC55649 on protein expression by employing antibody microarrays. As a consequence of RARb2 treatment, we observed that about 40 (out of 224) proteins examined with the array were increased by 2-fold or more, and of these, most were found to be related to the Ap1/c-Jun pathway after Pathway Architect examination. The results obtained from these studies may result in novel differentiation strategies for the generation in culture of homogeneous cell populations.