Rice R H, Wong V J, Pinkerton K E, Sundberg J P
Department of Environmental Toxicology, University of California, Davis 95616-8588, USA.
Anat Rec. 1999 Feb 1;254(2):231-7. doi: 10.1002/(SICI)1097-0185(19990201)254:2<231::AID-AR9>3.0.CO;2-6.
Cross-linking defects in hair cuticle have been observed in certain rare human disorders (trichothiodystrophy, transglutaminase-deficient lamellar ichthyosis). The hypothesis being investigated is that defective cross-linking in the cuticle or other parts of the fiber is a feature of some mouse mutants in which the hair is sparse or appears structurally unsound. Pelage hair samples from 13 mouse mutants displaying defective hair were extracted with sodium dodecyl sulfate and dithiothreitol at neutral pH and examined by transmission electron microscopy. All samples were indistinguishable after extraction from normal hair fibers in appearance of the medulla and cortex. In the cortex, keratins were completely extractable, but material remaining at the cell boundaries was clearly evident. Cells of the medulla were largely unextracted, containing distinct nuclei and amorphous material in the cytoplasm. In two samples (from mice with the matted/flaky tail and naked mutations) cells of the cuticle, which readily detached from the fiber when incubated at 100 degrees C, were more extensively extracted than normal. Defective cross-linking is thus observable in a minority of mouse hair mutants. The observed perturbation of cross-linking in the cuticle was not accompanied by visible perturbation in the cortex or medulla, indicating that different proteins participate in cross-linking in the different cell types.
在某些罕见的人类疾病（毛发硫营养不良、转谷氨酰胺酶缺乏性板层状鱼鳞病）中已观察到毛小皮中的交联缺陷。正在研究的假设是，纤维的小皮或其他部分中的交联缺陷是一些毛发稀疏或结构上看起来不健康的小鼠突变体的特征。从13个表现出毛发缺陷的小鼠突变体中采集的被毛样本，在中性pH值下用十二烷基硫酸钠和二硫苏糖醇提取，并用透射电子显微镜检查。从正常毛发纤维中提取后，所有样本在髓质和皮质外观上都无法区分。在皮质中，角蛋白可完全提取，但细胞边界处残留的物质清晰可见。髓质细胞大部分未被提取，细胞质中含有明显的细胞核和无定形物质。在两个样本（来自有缠结/片状尾巴和无毛突变的小鼠）中，当在100摄氏度下孵育时容易从纤维上脱落的小皮细胞比正常情况被更广泛地提取。因此，在少数小鼠毛发突变体中可观察到交联缺陷。在小皮中观察到的交联扰动在皮质或髓质中并未伴有明显的扰动，这表明不同的蛋白质参与了不同细胞类型中的交联。
