Ryudocan expression and its regulation

Ryudocan是一种细胞表面硫酸肝素蛋白聚糖，是syndecan家族的成员，syndecan-4，具有抗凝血特性。我们通过原位杂交研究了ryudocan在小鼠卵巢组织中的表达，发现ryudocan在颗粒细胞4- 5 b型卵泡中表达，并且在闭锁卵泡中表达最强烈。Ryudocan的表达与年龄和性周期阶段无关。与Ryudocan相比，syndecan-1和syndecan-3在排卵后卵泡和黄体中表达更丰富，而在4- 5 b型卵泡中表达较少，在闭锁卵泡中表达更少。因此，ryudocan可以在卵巢颗粒细胞中表达，并分泌到卵泡液中，以维持其流动性。研究表明，Ryudocan在多种生物学功能中发挥重要作用，包括调节血液凝固、细胞粘附和bFGF信号传导。然而，关于其表达的调节知之甚少。我们研究了缺氧对小鼠LTA细胞中ryudocan表达的影响，发现缺氧处理上调ryudocan和VEGF的基因表达。因此，ryudocan将由缺血组织中的缺氧刺激诱导，并通过生物介质如肝素结合生长因子（包括bFGF、VEGF和中期因子）作为组织修复分子发挥作用。

Ryudocan is a cell surface heparin sulfate proteoglycan, a member of the syndecan family, syndecan-4, that have anticoagulant property. We investigated the ryudocan expression in mouse ovarian tissues by in situ hybridization, and found that ryudocan is expressed in the granulosa cells type-4-5b follicles and, most intensely, in those of the atretic follicles. There is no relationship between ryudocan expression and age or sexual cycle stage. Compared with ryudocan expression, syndecan-1 and -3 are expressed more abundantly in postovulatory follicles and the corpora lutea, but less in the type 4-5b follicles and much less in the atretic follicles. Thus, ryudocan could be expressed in ovarian granulosa cells and secrete into follicular fluid to maintain its fluidity. It has been reported that ryudocan may play an important role in a variety of biological functions including regulation of blood coagulation, cell adhesion, and bFGF signaling. A little is known, however, regarding the regulation of its expression. We examined that hypoxia effect on ryudocan expression in the mouse LTA cells, and found that hypoxia treatment up-regulates the gene expression of ryudocan as well as VEGF. Thus, ryudocan would be induced by hypoxia stimuli in ischemic tissues, and function as a tissue-repairing molecule via biologic mediators such as heparin-binding growth factors including bFGF, VEGF, and midkine.