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MECHANISM OF TRANSDIFFERENTIATION OF MULTIPOTENT EPITHELIUM OF ASCIDIANS.

海鞘多能上皮的转分化机制。

基本信息

批准号：
06839020
负责人：
FUJIWARA Shigeki
金额：
$ 1.15万
依托单位：
KOCHI UNIVERSITY
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (C)
财政年份：
1994
资助国家：
日本
起止时间：
1994 至 1996
项目状态：
已结题

项目摘要

During bud development of the ascidian Polyandrocarpa misakiensis, most tissues are formed from the differentiated multipotent atrial epithelium via a process called transdifferentiation. Recently a cell line was established from the atrial epithelium of this species. Using this cell line as an assay system, an aminopeptidase was purified. This enzyme induced proliferation and differentiation of the cell line. A cDNA clone encoding the enzyme was isolated. The amino acid sequence deduced from the cDNA contained the consensus sequence for active site of thiol proteases and five repeats of trefoil growth factor motifs. Since aminopeptidase activity increased during early stages of bud development, this growth factor is suggested to play an important role in bud development.The aminopeptidase activity can be induced by retinoic acid. Several lines of evidence suggests that retinoic acid is actually synthesized in the developing bud. Complementary DNA clones encoding several types of aldehyde dehydrogenases, which are candidates for retinoic acid synthase, were isolated and characterized. The amounts of mRNAs for two of the clones increased during bud development. Complementary DNAs encoding a homologue of retinoic acid receptors and retinoidX receptors were also cloned. The ascidian RAR was expressed in the mesenchymal cells of developing buds, and the expression was induced by retinoic acid.Differential display was performed to screen cDNAs of which expression were induced or enhanced by retinoic acid. One of the isolated clones encoded a homologue of trypsin-like serine proteases. Since trypsin can induce dedifferentiation of the atrial epithelium, the polypeptide encoded by this cDNA may be involved in bud development.

在海鞘的芽发育过程中，大多数组织是由分化的多能心房上皮通过一个称为转分化的过程形成的。最近，从该物种的心房上皮细胞中建立了一个细胞系。使用该细胞系作为测定系统，纯化氨肽酶。这种酶诱导细胞系的增殖和分化。分离编码该酶的cDNA克隆。从cDNA推导的氨基酸序列包含巯基蛋白酶活性位点的共有序列和三叶生长因子基序的5个重复。由于氨肽酶活性在芽发育的早期阶段增加，这种生长因子被认为在芽发育中起重要作用。几条证据表明，视黄酸实际上是在发育中的芽中合成的。互补DNA克隆编码几种类型的醛脱氢酶，这是视黄酸合酶的候选人，进行了分离和表征。两个克隆的mRNA量在芽发育过程中增加。还克隆了编码视黄酸受体和类视黄酸X受体的同源物的互补DNA。海鞘RAR在发育中的芽间充质细胞中表达，视黄酸诱导海鞘RAR的表达，差异显示法筛选出视黄酸诱导或增强海鞘RAR表达的cDNA。其中一个分离的克隆编码胰蛋白酶样丝氨酸蛋白酶的同源物。由于胰蛋白酶可以诱导心房上皮细胞的去分化，因此该cDNA编码的多肽可能参与芽的发育。