GLYCOBIOLOGICAL STUDY OF TREATMENT OF RETINAL DISEASES

分别用持续光照大鼠和视网膜母细胞瘤培养细胞进行视网膜色素变性和视网膜母细胞瘤治疗的基础研究。(1) Jacalin（特异于粘蛋白型碳水化合物）、半乳糖凝集素-3（一种内源性动物凝集素）和神经氨酸酶抑制剂（2,3-脱氢-2-脱氧- n-乙酰神经氨酸）抑制光感受器细胞退化过程。半乳糖凝集素-3被认为通过视网膜感光细胞变性发挥抗凋亡作用。(2)利用抗牛核心蛋白抗体分离人和大鼠光感受器细胞相关黏液样糖蛋白（MLGAPC）核心蛋白cdna。MLGAPC不仅存在于光感受器间基质中，还存在于突触间隙基质中。通过检测MLGAPC在发育大鼠视网膜中的表达，我们确定了低分子型和高分子型分别对应于锥型和杆状型。由于MLGAPC的mrna表达在光感受器细胞成熟后下降，因此认为MLGAPC的周转速度较慢。该蛋白的这一特性有利于MLGAPC维持光感受器和外突触层的稳定结构。(3)将人MLGAPC核心蛋白cDNA导入Y79视网膜母细胞瘤细胞。凝集素印迹分析显示，它们产生了带有末端唾液酸的棒状MLGAPC。由于在培养基中加入透明质酸后，未观察到培养细胞的形态变化，因此认为MLGAPC与透明质酸的相互作用不足以使细胞粘附。

Basic studies for treatments of retinitis pigmentosa and retinoblastoma were performed using rats with constant light-exposure and culture cells of retinoblastoma, respectively. (1) Jacalin (specific for mucin type carbohydrates), galectin-3 (an endogenous animal lectin), and neuraminidase-inhibitor (2,3-dehydro-2-deoxy-N- acetylneuraminic acid) inhibited the process of photoreceptor cell-degeneration. Galectin-3 was considered to play anti-apoptotic role in the retina through photoreceptor cell-degeneration. (2) cDNAs of human and rat core proteins of mucinlike glycoprotein associated with photoreceptor cells (MLGAPC) were isolated using anti-bovine core protein antibody. The MLGAPC was detected not only in the interphotoreceptor matrix but also in the synaptic cleft matrix. By examining the expression of the MLGAPC in developing rat retinas, we determined that the low and high molecular types corresponded to cone and rod types, respectively. Since the mRNA-expression of the MLGAPC decreased after the maturation of the photoreceptor cells, the turnover-rate of MLGAPC was considered to be slow. This feature of the protein is convenient for the MLGAPC to maintain a stable structure of the photoreceptor and outer synaptic layers. (3) The cDNA of human core protein of MLGAPC was introduced into Y79 retinoblastoma cells. Lectin-blot analysis revealed that they produced rod-type MLGAPC with terminal sialic acids. Since no morphological change of the culture cells was observed after the addition of hyaluronan into the cultire medium, the interaction between MLGAPC and hyaluronan was considered to be insufficient for cellular adhesion.