GPI ANCHORED PROTEIN DEFICIENCIES IN CELLS FROM PSORIATIC SKIN

广泛的真核生物蛋白质都附着在细胞上 表面的糖基磷脂酰肌醇（GPI锚）。 等 蛋白质包括神经细胞粘附分子、衰变 加速因子，羊瘙痒症朊蛋白，叶酸受体，Thy-1 抗原和锥虫变体表面糖蛋白。 的 GPI锚的中心特征是：（I） 磷脂酰肌醇，其包埋在质膜中; 和（ii）线性聚糖茎（1个葡糖胺残基，接着3个葡糖胺残基）， 甘露糖残基，其中乙醇胺-P残基连接到 第三甘露糖）与葡糖胺连接的糖苷键 磷脂酰肌醇的肌醇残基。 的 蛋白质分子的羧基末端连接到 预组装的GPI锚通过的胺基 乙醇胺-P. Psphyrin是一种影响许多人的皮肤病， 个人，但其原因不明。最近，组织化学 分析表明，GPI锚定蛋白是高度 缺乏牛皮癣皮肤。这可能是由于（a）缺陷 预组装锚钉的合成;（B）未能将锚钉连接到 - 通过磷脂酶酶促裂解锚; 和/或（d）GPI锚定蛋白的蛋白水解降解。 研究所有这些可能性的方法已经被描述 在文献中详细介绍，并可在P.I.~ S 实验室 这项提案的实验将直接决定 GPI锚定蛋白的生物合成或催化是否 银屑病患者皮肤中的细胞有缺陷。 的 方法是应用GPI锚点分析的成熟方法， 银屑病成纤维细胞和角质形成细胞的原代培养物。 在 此外，基于P.I.~ S 涉及使用合成GPI类似物的实验室也将 用来解决这个问题。

Abroad spectrum of eukaryotic proteins are attached to cell surfaces by glycosylphosphatidylinositol (GPI) anchors. Such proteins include neuronal cell adhesion molecule, decay accelerating factor, scrapie prion protein, folate receptor, Thy-1 antigen, and the trypanosoma variant surface glycoprotein. The central features of GPI anchors are: (I) a residue of phosphatidylinositol, which is embedded in the plasma membrane; and (ii) a linear glycan stalk (1 glucosamine residue followed by 3 mannose residues, with a residue of ethanolamine-P linked to the 3rd mannose) with a glycosidic linkage attaching the glucosamine residue to the inositol residue of the phosphatidylinositol. The carboxy-terminal ends of protein molecules are attached to preassembled GPI anchors through the amine group of the ethanolamine-P. Psoriasis is a skin disease which affects many individuals, but its cause is unknown. Recently, histochemical analyses have suggested that GPI anchored proteins are highly deficient in psoriatic skin. This could be caused by (a) defective synthesis of preassembled anchors; (b) failure to attach anchors to proteins; ~ enzymatic cleavage of the anchors by phospholipases; and/or (d) proteolytic degradation of GPI anchored proteins. Methods for studying all of these possibilities have been described in the literature in detail, and are available in the P.I.~s laboratory. Experiments in this proposal will determine directly whether biosynthesis or catabolism of GPI anchored proteins is defective in cells derived from patients with psoriasis skin. The approach is to apply proven methods for GPI-anchor analysis to primary cultures of psoriatic fibroblasts and keratinocytes. In addition, a novel approach based upon recent research in the P.I.~s laboratory involving the use of synthetic GPI analogues will also be used to address this question.