Tarutani M, Itami S, Okabe M, Ikawa M, Tezuka T, Yoshikawa K, Kinoshita T, Takeda J
Department of Dermatology, Osaka University Medical School, 2-2 Yamadaoka, Suita, Osaka 565, Japan.
Proc Natl Acad Sci U S A. 1997 Jul 8;94(14):7400-5. doi: 10.1073/pnas.94.14.7400.
Glycosylphosphatidylinositol (GPI)-anchored proteins are widely distributed on plasma membranes of eukaryotes. More than 50 GPI-anchored proteins have been shown to be spatiotemporally expressed in mice with a deficiency of GPI-anchor biosynthesis that causes embryonic lethality. Here, we examine the functional roles of GPI-anchored proteins in mouse skin using the Cre-loxP recombination system. We disrupted the Pig-a gene, an X-linked gene essential for GPI-anchor biosynthesis, in skin. The Cre-mediated Pig-a disruption occurred in skin at almost 100% efficiency in male mice bearing two identically orientated loxP sites within the Pig-a gene. Expression of GPI-anchored proteins was completely absent in the skin of these mice. The skin of such mutants looked wrinkled and more scaly than that of wild-type mice. Furthermore, histological examination of mutant mice showed that the epidermal horny layer was tightly packed and thickened. Electron microscopy showed that the intercellular space was narrow and there were many small vesicles embedded in the intercellular space that were not observed in equivalent wild-type mouse skin preparations. Mutant mice died within a few days after birth, suggesting that Pig-a function is essential for proper skin differentiation and maintenance.
糖基磷脂酰肌醇（GPI）锚定蛋白广泛分布于真核生物的质膜上。已证实，超过50种GPI锚定蛋白在因GPI锚生物合成缺陷而导致胚胎致死的小鼠中呈现时空表达。在此，我们利用Cre-loxP重组系统研究GPI锚定蛋白在小鼠皮肤中的功能作用。我们破坏了皮肤中Pig-a基因，这是一个对GPI锚生物合成至关重要的X连锁基因。在Pig-a基因内带有两个同向loxP位点的雄性小鼠中，Cre介导的Pig-a破坏在皮肤中的效率几乎达到100%。这些小鼠的皮肤中完全不存在GPI锚定蛋白的表达。此类突变小鼠的皮肤比野生型小鼠的皮肤看起来更皱且鳞屑更多。此外，对突变小鼠的组织学检查显示，表皮角质层紧密堆积且增厚。电子显微镜检查表明，细胞间隙变窄，细胞间隙中有许多小泡，而在同等的野生型小鼠皮肤标本中未观察到这些小泡。突变小鼠在出生后几天内死亡，这表明Pig-a功能对于皮肤的正常分化和维持至关重要。
