Zhao H, Boissy Y L, Abdel-Malek Z, King R A, Nordlund J J, Boissy R E
Department of Dermatology, University of Cincinnati College of Medicine, Ohio.
Lab Invest. 1994 Jul;71(1):25-34.
The Chediak-Higashi syndrome (CHS) is a disorder that affects the synthesis and/or maintenance of storage/secretory granules in various types of cells. Lysosomes of leukocytes and fibroblasts, dense bodies of platelets, azurophilic granules of neutrophils and melanosomes of melanocytes are generally larger in size and irregular in morphology, indicating that a common pathway in storage organellogenesis is affected in patients with CHS.
A pure line of melanocytes has been established using a 2 cm2 shave biopsy from a child with CHS. This 4-week-old male patient had oculocutaneous albinism and expressed neutropenia, impaired platelet function, and no natural killer cell activity. The cultured CHS melanocytes were analyzed for cell biological and biochemical aberrancies.
Cultured melanocytes demonstrated some large and/or complexed melanosomes that resembled those observed in melanocytes from ultrastructural sections of the biopsy. Cytoplasmic localization of tyrosinase, tyrosinase-related protein-1 and granulophysin (a 40 kilodalton membrane protein originally identified as a component in dense bodies of platelets) demonstrated a prominent perinuclear accumulation. The basal synthesis of melanin and the activity levels of tyrosine hydroxylase, dihydroxyphenylalanine (DOPA) oxidase, or DOPAchrome tautomerase were comparable to control Caucasian melanocytes in culture. However, melanin synthesis as well as the catalytic activities of tyrosinase were not dramatically upregulated in CHS melanocytes by the addition of isobutyl methylxanthine and cholera toxin in the growth medium when parameters were assayed in cell lysates. In contrast, when assays were performed using live cells, tyrosine hydroxylase demonstrated dramatic upregulation. Medium conditioned by CHS melanocytes demonstrated phenylthiourea-inhibitable tyrosinase activity. Melanocyte lysates and conditioned medium analyzed by sodium dodecyl sulfate-polyacrylamide gel electrophoresis and DOPA staining showed an extra, approximately 100 kilodalton soluble protein band with DOPA positivity and tyrosinase immunoreactivity. In addition to tyrosinase, one of three lysosomal enzymes assayed (beta-glucuronidase) was aberrantly secreted into the medium.
These results demonstrate that melanocytes cultured from CHS express a defect in the structure and/or function of the melanosome and abnormal trafficking of some cellular proteins.
切迪阿克-东综合征（CHS）是一种影响多种类型细胞中储存/分泌颗粒合成和/或维持的疾病。白细胞和成纤维细胞的溶酶体、血小板的致密体、中性粒细胞的嗜天青颗粒以及黑素细胞的黑素体通常体积更大且形态不规则，这表明CHS患者储存细胞器发生过程中的一条共同途径受到了影响。
利用一名CHS患儿2平方厘米的剃刀活检组织建立了纯系黑素细胞。这名4周大的男性患者患有眼皮肤白化病，表现出中性粒细胞减少、血小板功能受损且无自然杀伤细胞活性。对培养的CHS黑素细胞进行细胞生物学和生化异常分析。
培养的黑素细胞显示出一些大的和/或复合的黑素体，类似于活检超微结构切片中黑素细胞所观察到的情况。酪氨酸酶、酪氨酸酶相关蛋白-1和颗粒体蛋白（一种最初被鉴定为血小板致密体成分的40千道尔顿膜蛋白）的细胞质定位显示出明显的核周聚集。黑素的基础合成以及酪氨酸羟化酶、二羟基苯丙氨酸（DOPA）氧化酶或多巴色素互变异构酶的活性水平与培养的对照白种人黑素细胞相当。然而，当在细胞裂解物中检测参数时，在生长培养基中添加异丁基甲基黄嘌呤和霍乱毒素后，CHS黑素细胞中的黑素合成以及酪氨酸酶的催化活性并未显著上调。相反，当使用活细胞进行检测时，酪氨酸羟化酶表现出显著上调。CHS黑素细胞条件培养基显示出苯硫脲可抑制的酪氨酸酶活性。通过十二烷基硫酸钠-聚丙烯酰胺凝胶电泳和DOPA染色分析的黑素细胞裂解物和条件培养基显示出一条额外的、约100千道尔顿的可溶性蛋白带，具有DOPA阳性和酪氨酸酶免疫反应性。除酪氨酸酶外，所检测的三种溶酶体酶之一（β-葡萄糖醛酸酶）异常分泌到培养基中。
这些结果表明，从CHS培养的黑素细胞在黑素体的结构和/或功能以及一些细胞蛋白的异常运输方面存在缺陷。
