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.

在海鞘层毛果片的芽发育过程中，大多数组织都是由分化的多能心房上皮形成的。最近，该物种的心房上皮建立了细胞系。使用该细胞系作为测定系统，纯化了氨基肽酶。该酶诱导细胞系的增殖和分化。分离了编码该酶的cDNA克隆。从cDNA推导的氨基酸序列包含硫醇蛋白酶活性位点的共有序列和三叶生长因子基序的五个重复。由于氨基肽酶活性在芽发育的早期阶段增加，因此建议这种生长因子在芽发育中起重要作用。视黄酸可以诱导氨基肽酶活性。几条证据表明，在发育中的芽中实际上合成了视黄酸。分离并表征了编码几种类型的醛脱氢酶的互补DNA克隆，它们是视黄酸合酶的候选者。在芽发育过程中，两个克隆的mRNA量增加。还克隆了视黄酸受体和视黄素受体的同源物的互补DNA。西西rar在发育中的芽的间充质细胞中表达，并通过视黄酸诱导表达。对视黄酸诱导或增强表达的筛选cDNA进行了不同的显示。孤立的克隆之一编码了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的去分化，因此该cDNA编码的多肽可能参与芽发育。