Dawson G, Kilkus J, Siakotos A N, Singh I
Department of Pediatrics, University of Chicago, IL 60637, USA.
Mol Chem Neuropathol. 1996 Oct-Dec;29(2-3):227-35. doi: 10.1007/BF02815004.
The storage of subunit c of mitochondrial ATP synthase, other hydrophobic peptides, and autofluorescent pigment in both late infantile (CLN2) and juvenile (CLN3) neuronal ceroid lipofuscinosis, but not in infantile (CLN1), has raised the question of abnormal mitochondrial function. We now report a partial deficiency in three types of fatty acid oxidation in intact skin fibroblasts from CLN2 and CLN3 patients, but not CLN1. We observed a statistically significant 33% reduction in palmitate (beta-oxidation; mainly mitochondrial) and lignocerate (beta-oxidation; mainly peroxisomal), and a 50% reduction in phytanic acid (alpha-oxidation; mainly peroxisomal) in the absence of exogenous carnitine. In contrast, when we measured fatty acid beta-oxidation (lignoceric acid and palmitic acid), in the same human skin fibroblasts, following lysis in the presence of carnitine, we found no difference in enzyme activity among normal, CLN1, CLN2, and CLN3. However, we did observe a 40% reduction in peroxisomal particulate (bound) catalase activity in CLN1 and CLN2 fibroblasts, which typically results from organellar lipid accumulation or a membrane abnormality. However, total catalase levels were normal, and Western blot analysis of this and three other major oxidant protective enzymes (Mn-dependent superoxide dismutase [MnSOD], CuZn-dependent superoxide dismutase [CuZnSOD], and glutathione peroxidase) were normal in CLN1, CLN2, and CLN3, as well as in liver from an animal (English Setter dog) model for CLN, which shows similar pathology and subunit c storage. Our data showing differences between CLN1 and forms CLN2 and CLN3 suggest some type of mitochondrial membrane abnormality as the source of the pathology in CLN2 and CLN3.
线粒体ATP合酶亚基c、其他疏水肽以及自身荧光色素在晚期婴儿型（CLN2）和青少年型（CLN3）神经元蜡样脂褐质沉积症中均有蓄积，但在婴儿型（CLN1）中却没有，这引发了线粒体功能异常的问题。我们现在报告，CLN2和CLN3患者的完整皮肤成纤维细胞中三种脂肪酸氧化存在部分缺陷，但CLN1患者的细胞没有。在没有外源性肉碱的情况下，我们观察到棕榈酸（β-氧化；主要在线粒体中）和木蜡酸（β-氧化；主要在过氧化物酶体中）的氧化显著降低了33%，植烷酸（α-氧化；主要在过氧化物酶体中）的氧化降低了50%。相比之下，当我们在相同的人皮肤成纤维细胞中加入肉碱裂解后测量脂肪酸β-氧化（木蜡酸和棕榈酸）时，我们发现正常、CLN1、CLN2和CLN3之间的酶活性没有差异。然而，我们确实观察到CLN1和CLN2成纤维细胞中的过氧化物酶体颗粒（结合）过氧化氢酶活性降低了40%，这通常是由细胞器脂质蓄积或膜异常导致的。然而，总过氧化氢酶水平正常，对CLN1、CLN2和CLN3以及CLN动物（英国塞特犬）模型肝脏中的这种酶和其他三种主要抗氧化酶（锰依赖性超氧化物歧化酶[MnSOD]、铜锌依赖性超氧化物歧化酶[CuZnSOD]和谷胱甘肽过氧化物酶）进行的蛋白质印迹分析也均正常，该动物模型表现出类似的病理特征和亚基c蓄积。我们的数据显示CLN1与CLN2和CLN3型之间存在差异，这表明某种类型的线粒体膜异常是CLN2和CLN3病理的根源。
