Functional analysis of cell adhesion molecule, JAM-4S, specifically expressed in tissue specific stem cells.

在这个项目中，我们专注于分析分子，特别是细胞表面分子，这些分子通常在几种组织特异性干细胞中表达，因为组织特异性干细胞表现出非常相似的特性。然后，我们克隆了一种细胞粘附分子JAM-4，它在造血干细胞和雄性生殖干细胞中均有表达，我们从干细胞中克隆的JAM-4转录本，命名为JAM-4S，它比从肾和肺中克隆的短。该转录物编码JAM-4蛋白的同种型，其仅含有一个免疫球蛋白结构域。因此，我们分析了JAM-4S蛋白和JAM-4蛋白在男性生殖系统和造血系统干细胞中的功能。在睾丸中，JAM-4S在新生期的生殖母细胞和精原细胞中表达。在造血系统中，JAM-4S在骨髓干细胞和祖细胞中都有表达，为了了解其在体内的生物学功能，我们制备了JAM-4缺陷小鼠。由于很难产生JAM-4S特异性敲除小鼠，我们产生了常规的JAM-4敲除小鼠。JAM-4缺陷小鼠至少存活2年，未见明显异常。JAM-4基因缺陷小鼠的睾丸标本显示正常发育。JAM-4缺陷小鼠的造血也是正常的。在睾丸和骨髓中，JAM-4家族分子如JAM-A和JAM-B也表达。因此，我们将产生JAM-B/JAM-4-双敲除小鼠以分析干细胞群体的表型。

In this project, we focused on the analysis of molecule(s), especially cell surface molecule(s), which are commonly expressed in several tissue specific stem cells because tissue specific stem cells show quite similar properties. Then, we have cloned one of the cell adhesion molecules, JAM-4, which are expressed in both hematopoietic stem cells and male germ stem cells.The JAM-4 transcript, named JAM-4S, which we have cloned from stem cells is shorter than that cloned from kidney and lung. The transcript encoded an isoform of JAM-4 protein, which only contain one immunoglobulin domain. Therefore, we analyzed the function of JAM-4S protein as well as JAM-4 protein in the stem cells at male reproduction system and hematopoietic system. In testes, JAM-4S is expressed in gonocytes and spermatogonia at neonatal stage. In hematopoietic system, JAM-4S is expressed in both stem cell-and progenitor-populations in bone marrow cells.In order to understand the biological function in vivo, we have generated the JAM-4 deficient mice. Because it is difficult to generate JAM-4S specific knock out mice, we have generated conventional JAM-4 knock out mice. The JAM-4 deficient mice alive at least 2 years so far and do not show obvious abnormality. The testes specimen of JAM-4 deficient mice showed normal development. The hematopoiesis of the JAM-4 deficient mice was also normal. In testes and bone marrow, the family molecules of JAM-4, such as JAM-A and JAM-B are also expressed. Therefore, we are going to generate JAM-B/JAM-4-double knock out mice to analyze the phenotype on stem cell population.