PBX AND Retinoic Acid-dependent Differentiation

描述（由申请人提供）：视黄酸（RA）是维生素A最有效的生物活性形式，在生长、分化、免疫反应、生殖和胚胎发育过程中起重要作用。母体维生素A不足和过量都与发育异常有关。RA治疗P19胚胎癌细胞可根据培养条件分化为内胚层细胞或神经元细胞。b细胞白血病前转录因子1 （PBX1）、PBX2和PBX3 mRNA水平以及PBX1/2/3蛋白水平在P19细胞RA治疗后升高。PBX蛋白作为二聚体伴侣与几种HOX蛋白在发育过程中介导基因表达。这种ra依赖性的PBX1/2/3表达的增加已被证明是P19细胞向内胚层细胞和神经元细胞分化的关键。此外，在内胚层细胞分化过程中，骨形态发生蛋白4 （bone morphogenetic protein 4, BMP4）和装饰素（decornin， DCN）这两个基因的表达需要ra依赖性地增加PBX1/2/3的表达。这些研究的目的是阐明在P19细胞向内胚层和神经元细胞分化过程中，这种ra依赖性的PBX1/2/3水平的增加所起的作用。因此，我们计划：(1)进一步表征PBX172/3蛋白在P19细胞向内胚层、神经元和心脏细胞分化过程中的作用；(2)确定是否需要PBX1/2/3蛋白诱导BMP4和/或DCN表达，以使ra依赖的P19细胞分化为内胚层和/或神经元细胞；(3)在ra依赖性P19细胞向内胚层细胞和神经元细胞分化过程中，鉴定和表征pbx1 /2/3调控的其他基因。这些研究将进一步了解PBX在哺乳动物发育过程中的作用，并进一步阐明分化过程中依赖ra的信号通路的细节。

DESCRIPTION (provided by applicant): Retinoic acid (RA), the most potent biologically active form of vitamin A, plays an important role during growth, differentiation, immune response, reproduction, and embryonic development. Both maternal insuffiency and maternal excess of vitamin A are associated with developmental abnormalities. RA treatment of P19 embryonal carcinoma cells causes differentiation to either endodermal or neuronal cells, depending on the culture conditions. Pre-B cell leukemia transcription factor 1 (PBX1), PBX2 and PBX3 mRNA levels, and PBX1/2/3 protein levels are elevated upon treatment of P19 cells with RA. PBX proteins function as dimeric partners with several HOX proteins mediating gene expression during development. This RA-dependent increase in PBX1/2/3 expression has been demonstrated to be critical for differentiation of P19 cells to both endodermal and neuronal cells. In addition, the expression of two genes, bone morphogenetic protein 4 (BMP4) and decornin (DCN) have been shown to require RA-dependent increase in PBX1/2/3 expression during endodermal cell differentiation. The goal of the proposed studies is to elucidation the role of this RA-dependent increase in PBX1/2/3 levels during differentiation of P19 cells to endodermal and neuronal cells. We therefore plan: (1) to further characterize the role of PBX172/3 proteins during differentiation of P19 cells to endodermal, neuronal and cardiac cells; (2) to determine if induction of BMP4 and/or DCN expression by PBX1/2/3 proteins is required for RA-dependent differentiation of P19 cells to endodermal and/or neuronal cells; and (3) to identify and characterize additional PBX1/2/3-regulated genes during RA-dependent differentiation of P19 cells to endodermal and neuronal cells. These studies will further the understanding of the role of PBX during mammalian development and further elucidate the details of one RA-dependent pathway of signaling during differentiation.