Edvardson Simon, Kose Shingo, Jalas Chaim, Fattal-Valevski Aviva, Watanabe Ai, Ogawa Yutaka, Mamada Hiroshi, Fedick Anastasia M, Ben-Shachar Shay, Treff Nathan R, Shaag Avraham, Bale Sherri, Gärtner Jutta, Imamoto Naoko, Elpeleg Orly
The Monique and Jacques Roboh Department of Genetic Research, Hadassah, Hebrew University Medical Center, Jerusalem, Israel.
Cellular Dynamics Laboratory, RIKEN, 2-1 Hirosawa, Wako, Saitama, Japan.
J Med Genet. 2016 Feb;53(2):132-7. doi: 10.1136/jmedgenet-2015-103232. Epub 2015 Nov 6.
Leukodystrophies are genetic white matter disorders affecting the formation or maintenance of myelin. Among the recently discovered genetic defects associated with leukodystrophies, several genes converge on a common mechanism involving protein transcription/translation and ER stress response.
The genetic basis of a novel congenital leukodystrophy, associated with early onset spastic paraparesis, acquired microcephaly and optic atrophy was studied in six patients from three unrelated Ashkenazi-Jewish families. To this end we used homozygosity mapping, exome analysis, western blot (Hikeshi, HSF1-pS326 and b-actin) in patient fibroblasts, indirect immunofluorescence (HSP70 and HSF1) in patient fibroblasts undergoing heat shock stress, nuclear injection of plasmids expressing Hikeshi or EGFP in patient fibroblasts, in situ hybridization and Immunoblot analysis of Hikeshi in newborn and adult mouse brain.
All the patients were homozygous for a missense mutation, p.Val54Leu, in C11ORF73 encoding HSP70 nuclear transporter protein, Hikeshi. The mutation segregated with the disease in the families and was carried by 1:200 Ashkenazi-Jewish individuals. The mutation was associated with undetectable level of Hikeshi in the patients' fibroblasts and with lack of nuclear HSP70 during heat shock stress, a phenomenon which was reversed upon the introduction of normal human Hikeshi to the patients cells. Hikeshi was found to be expressed in central white matter of mouse brain.
These data underscore the importance of Hikeshi for HSP70 relocation into the nucleus. It is likely that in the absence of Hikeshi, HSP70 cannot attenuate the multiple heat shock induced nuclear phenotypes, leaving the cells unprotected during heat shock stress. We speculate that the sudden death of three of the six patients following a short febrile illness and the life-threatening myo-pericarditis in the fourth are the result of excess extra-nuclear HSP70 level which initiates cytokine release or provide target for natural killer cells. Alternatively, nuclear HSP70 might play an active role in stressed cells protection.
脑白质营养不良是影响髓鞘形成或维持的遗传性白质疾病。在最近发现的与脑白质营养不良相关的基因缺陷中，有几个基因汇聚于一个涉及蛋白质转录/翻译和内质网应激反应的共同机制。
对来自三个不相关的阿什肯纳兹犹太家庭的六名患者进行了研究，该新型先天性脑白质营养不良与早发性痉挛性截瘫、后天性小头畸形和视神经萎缩有关。为此，我们使用了纯合性定位、外显子组分析、患者成纤维细胞的蛋白质免疫印迹法（Hikeshi、HSF1-pS326和β-肌动蛋白）、热休克应激下患者成纤维细胞的间接免疫荧光法（HSP70和HSF1）、患者成纤维细胞中表达Hikeshi或EGFP的质粒的核内注射、新生和成年小鼠脑内Hikeshi的原位杂交和免疫印迹分析。
所有患者在编码HSP70核转运蛋白Hikeshi的C11ORF73基因中存在一个错义突变p.Val54Leu的纯合子。该突变在家族中与疾病共分离，在1/200的阿什肯纳兹犹太个体中携带。该突变与患者成纤维细胞中无法检测到的Hikeshi水平以及热休克应激期间缺乏核HSP70相关，当将正常人的Hikeshi引入患者细胞后，这种现象得到逆转。发现Hikeshi在小鼠脑的中央白质中表达。
这些数据强调了Hikeshi对HSP70重新定位到细胞核的重要性。在没有Hikeshi的情况下，HSP70可能无法减轻多种热休克诱导的核表型，使细胞在热休克应激期间得不到保护。我们推测，六名患者中有三名在短暂发热性疾病后突然死亡，第四名患者出现危及生命的心肌心包炎，是由于核外HSP70水平过高导致细胞因子释放或为自然杀伤细胞提供靶点所致。或者，核HSP70可能在应激细胞保护中发挥积极作用。
