ZNHIT3 is defective in PEHO syndrome, a severe encephalopathy with cerebellar granule neuron loss
ZNHIT3 is defective in PEHO syndrome, a severe encephalopathy with cerebellar granule neuron loss
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DOI：
10.1093/brain/awx040
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发表时间：
2017-05-01
期刊：
影响因子：
14.5
通讯作者：
Lehesjoki, Anna-Elina
中科院分区：
文献类型：
--
作者：
Anttonen, Anna-Kaisa;Laari, Anni;Lehesjoki, Anna-Elina
进行性脑病伴水肿、高度心律失常和视神经萎缩（PEHO）综合征是一种儿童早期发病的严重常染色体隐性脑病，其特征是几乎全部颗粒神经元丢失导致的极端小脑萎缩。通过将芬兰家族的纯合性作图与位置候选基因的桑格测序和外显子组测序相结合，将ZNHIT 3中密码子31处亮氨酸对丝氨酸的纯合错义取代确定为PEHO综合征的主要原因。ZNHIT 3编码一种核锌指蛋白，以前参与转录调控和小核仁核糖核蛋白颗粒组装，因此可能参与前核糖体RNA加工。所鉴定的突变影响ZNHIT 3的锌指结构域中的高度保守的氨基酸残基。斑马鱼胚胎中znhit3的敲除和基因组编辑都重现了患者的小脑缺陷、小头畸形和水肿。这些表型被野生型所拯救，但不是突变的人ZNHIT 3 mRNA，这表明患者的错义取代通过功能丧失机制引起疾病。用ZNHIT 3表达载体转染细胞系显示PEHO综合征突变蛋白是不稳定的。小鼠小脑组织的免疫组织化学分析表明，ZNHIT 3表达在增殖颗粒细胞前体，在增殖和有丝分裂后的颗粒细胞，和浦肯野细胞。在培养的小鼠颗粒神经元和离体小脑切片中Znhit 3的敲低表明，Znhit 3对于颗粒神经元的存活和迁移是不可或缺的，这与斑马鱼的发现和患者的神经病理学一致。这些结果表明，核调节蛋白的功能丧失是PEHO综合征的基础，并暗示其时空相互作用靶点的建立将是开发治疗方法和提高对小脑发育的理解的基础。
Progressive encephalopathy with oedema, hypsarrhythmia, and optic atrophy (PEHO) syndrome is an early childhood onset, severe autosomal recessive encephalopathy characterized by extreme cerebellar atrophy due to almost total granule neuron loss. By combining homozygosity mapping in Finnish families with Sanger sequencing of positional candidate genes and with exome sequencing a homozygous missense substitution of leucine for serine at codon 31 in ZNHIT3 was identified as the primary cause of PEHO syndrome. ZNHIT3 encodes a nuclear zinc finger protein previously implicated in transcriptional regulation and in small nucleolar ribonucleoprotein particle assembly and thus possibly to pre-ribosomal RNA processing. The identified mutation affects a highly conserved amino acid residue in the zinc finger domain of ZNHIT3. Both knockdown and genome editing of znhit3 in zebrafish embryos recapitulate the patients' cerebellar defects, microcephaly and oedema. These phenotypes are rescued by wild-type, but not mutant human ZNHIT3 mRNA, suggesting that the patient missense substitution causes disease through a loss-of-function mechanism. Transfection of cell lines with ZNHIT3 expression vectors showed that the PEHO syndrome mutant protein is unstable. Immunohistochemical analysis of mouse cerebellar tissue demonstrated ZNHIT3 to be expressed in proliferating granule cell precursors, in proliferating and post-mitotic granule cells, and in Purkinje cells. Knockdown of Znhit3 in cultured mouse granule neurons and ex vivo cerebellar slices indicate that ZNHIT3 is indispensable for granule neuron survival and migration, consistent with the zebrafish findings and patient neuropathology. These results suggest that loss-of-function of a nuclear regulator protein underlies PEHO syndrome and imply that establishment of its spatiotemporal interaction targets will be the basis for developing therapeutic approaches and for improved understanding of cerebellar development.