Roles of activin/follistatin in neural induction

这个项目的目标是激发激活素和Folistatin在神经元诱导中的作用。在这个时期，我们得到了以下的发现。（1）与激活类型IIA receptor （ActRIIA）、which we named ARIP 1（activin receptor interacting protein 1 ）。通过使用两种混合筛选，我们分离了来自小鼠脑cDNA库的ARIP 1的cDNA克隆体。ARIPI在NH 2终端区域有一个瓜尼酯激酶域（Guk），由两个WW域和五个PDZ域（PDZ 1 -5）跟踪。ARIP1 interacted with ActRIIA through PDZ5。ActRIIA （E-S-S-L）的COOH-terminal residues（E-S-S-L）同意与PDZ绑定一致性动机，并确认ARIP 1一致性序列。ARIP 1特别与TGF-β家族中的ActRIIA相互作用。有趣的是，ARIP 1也与Smad 3相互作用，它是一种激活/TGF-β内聚信号分子。Mr. Mr. ... More ARIP 1的NA在其他问题上有更多的优势。ARIP 1控制在激活响应式细胞线中激活诱导和Smad 3诱导的转录的过度表达。这些发现建议指出，ARIP 1具有在特定亚细胞站点中装配信号分子的信号激活中的重要作用，并在神经细胞中调节信号转换。（2）一种新型类Folistatin蛋白质作为活性结合蛋白的特性;我们在人类和老鼠中发现了一种新型类Folistatin蛋白质，可以从已知的Folistatin基因产品中找到差异。Follistatin有三个Follistatin域，这些域预示着增长因素的结合动机。人类和小鼠都有类似的蛋白质，只有两个类似的蛋白质。Northen Blotting揭示了用于新的类Folistatin蛋白质的mRNAs在Placenta、Adrenal gland、Lung、Heart、Pituitary、Testis和Ovary中被广泛地表达的活性物质也是同样地表达的。通过共同免疫吸收分析发现的再组合蛋白质具有一种活性-结合活动。Furthermore，再组合蛋白抑制了激活-感应的转录反应，在激活-反应细胞中，我是一个剂量-依赖的杀手。Ligand blotting using y D1125 y D1 I-activin and GST-pull down分析揭示了C-终端区域中的第二个follistatin domain on the molecule is responsible for the activin-binding activity。在摘要中，我们已经确定了一种新颖的Folistatin持有活动-结合活动。我们发现的一个重要因素是，激活的细胞信号被严格地调节为follistatin家族的多个成员。Less（低）

The aim of this project is to elucidate the roles of activin and follistatin in neural induction in embryogenesis. In this period, we have obtained the following findings.(1) Identification and characterization of a PDZ protein.We have identified a mouse PDZ protein that interacts with the activin type IIA receptor (ActRIIA), which we named ARIP1 (activin receptor interacting protein 1 ). By using yeast two-hybrid screening, we isolated a cDNA clone of ARIP1 from a mouse brain cDNA library. ARIPI had one guanylate kinase domain (Guk) in the NH2-terminal region, followed by two WW domains and five PDZ domains (PDZ1-5). ARIP1 interacted with ActRIIA through PDZ5. The COOH-terminal residues of ActRIIA (E-S-S-L) agree with a PDZ-binding consensus motif, and ARIP1 recognized the consensus sequence. ARIP1 interacts specifically with ActRIIA among the receptors for TGF-β family. Interestingly, ARIP1 also interacted with Smad3, which is an activin/TGF-β intracellular signaling molecule. The mR … More NA of ARIP1 was more abundant in the brain that in other tissues. Overexpressin of ARIP1 controls activin-induced and Smad3-induced transcription in activin-responsive cell lines. These findings suggest that ARIP1 has a significant role in assembling activin signaling molecules at specific subcellular sites and in regulating signal transduction in neuronal cells.(2) Characterization of a novel follistatin-like protein as an activin-binding protein.We have identified a novel follistatin-like protein in humans and mice, which was found to differ from known follistatin gene products. Follistatin has three follistatin domains that are presumed to be growth factor binding motifs. Both the human and mouse follistatin-like proteins possessed only two follistatin domains. Northen blotting revealed that mRNAs for the novel follistatin-like proteins were abundantly expressed in placenta, adrenal gland, lung, heart, pituitary, testis and ovary, tissues where activins are also abundantly expressed. The recombinant proteins were found to have an activin-bindig activity as revealed by coimmunoprecipitation analysis. Furthermore, the recombinant protein inhibited activin-induced transcriptional responses in activin-responsive cells I n a dose-dependent manner. Ligand blotting using ィイD1125ィエD1I-activin and GST-pull down analysis revealed that the second follistatin domain in the C-terminal region on the molecule was responsible for the activin-binding activity. In summary, we have identified a novel follistatin possessing activin-binding activity. Our finding implies that cellular signaling of activin is tightly regulated by multiple members of the follistatin family. Less