Akinci Baris, Sankella Shireesha, Gilpin Christopher, Ozono Keiichi, Garg Abhimanyu, Agarwal Anil K
Division of Nutrition and Metabolic Diseases, Center for Human Nutrition, Department of Internal Medicine, University of Texas Southwestern Medical Center, Dallas, Texas 75390, USA.
Molecular and Cellular Imaging, Department of Cell Biology, University of Texas Southwestern Medical Center, Dallas, Texas 75390, USA.
Cold Spring Harb Mol Case Stud. 2017 Jan;3(1):a001339. doi: 10.1101/mcs.a001339.
Patients with progeroid syndromes such as mandibuloacral dysplasia, type B (MADB) and restrictive dermopathy (RD) harbor mutations in zinc metalloproteinase (ZMPSTE24), an enzyme essential for posttranslational proteolysis of prelamin A to form mature lamin A. Dermal fibroblasts from these patients show increased nuclear dysmorphology and reduced proliferation; however, the efficacy of various pharmacological agents in reversing these cellular phenotypes remains unknown. In this study, fibroblasts from MADB patients exhibited marked nuclear abnormalities and reduced proliferation that improved upon treatment with rapamycin and dimethylsulfoxide but not with other agents, including farnesyl transferase inhibitors. Surprisingly, fibroblasts from an RD patient with a homozygous null mutation in , resulting in exclusive accumulation of prelamin A with no lamin A on immunoblotting of cellular lysate, exhibited few nuclear abnormalities and near-normal cellular proliferation. An unbiased proteomic analysis of the cellular lysate from RD fibroblasts revealed a lack of processing of vimentin, a cytoskeletal protein. Interestingly, the assembly of the vimentin microfibrils in MADB fibroblasts improved with rapamycin and dimethylsulfoxide. We conclude that rapamycin and dimethylsulfoxide are beneficial for improving nuclear morphology and cell proliferation of MADB fibroblasts. Data from a single RD patient's fibroblasts also suggest that prelamin A accumulation by itself might not be detrimental and requires additional alterations at the cellular level to manifest the phenotype.
患有早衰综合征的患者，如B型下颌-肢端发育不良（MADB）和限制性皮肤病（RD），其锌金属蛋白酶（ZMPSTE24）发生突变，该酶是前体核纤层蛋白A进行翻译后蛋白水解以形成成熟核纤层蛋白A所必需的。这些患者的皮肤成纤维细胞显示出核畸形增加和增殖减少；然而，各种药物在逆转这些细胞表型方面的疗效仍不清楚。在本研究中，MADB患者的成纤维细胞表现出明显的核异常和增殖减少，用雷帕霉素和二甲基亚砜治疗后有所改善，但用其他药物（包括法尼基转移酶抑制剂）治疗则无改善。令人惊讶的是，一名RD患者的成纤维细胞在ZMPSTE24基因上存在纯合无效突变，导致细胞裂解物免疫印迹上仅积累前体核纤层蛋白A而无核纤层蛋白A，该成纤维细胞几乎没有核异常且细胞增殖接近正常。对RD成纤维细胞的细胞裂解物进行的无偏蛋白质组学分析显示，波形蛋白（一种细胞骨架蛋白）缺乏加工。有趣的是，MADB成纤维细胞中波形蛋白微纤维的组装在雷帕霉素和二甲基亚砜作用下得到改善。我们得出结论，雷帕霉素和二甲基亚砜有利于改善MADB成纤维细胞的核形态和细胞增殖。来自一名RD患者成纤维细胞的数据还表明，前体核纤层蛋白A的积累本身可能并无损害，需要细胞水平的其他改变才能表现出该表型。
