Department of Biochemistry, Emory University School of Medicine, Atlanta, Georgia, USA; Graduate Program in Biochemistry, Cell and Developmental Biology (BCDB), Emory University, Atlanta, Georgia, USA.
Department of Biochemistry, Emory University School of Medicine, Atlanta, Georgia, USA.
J Biol Chem. 2022 Sep;298(9):102261. doi: 10.1016/j.jbc.2022.102261. Epub 2022 Jul 14.
Regulation of protein synthesis is critical for control of gene expression in all cells. Ribosomes are ribonucleoprotein machines responsible for translating cellular proteins. Defects in ribosome production, function, or regulation are detrimental to the cell and cause human diseases, such as progressive encephalopathy with edema, hypsarrhythmia, and optic atrophy (PEHO) syndrome. PEHO syndrome is a devastating neurodevelopmental disorder caused by mutations in the ZNHIT3 gene, which encodes an evolutionarily conserved nuclear protein. The precise mechanisms by which ZNHIT3 mutations lead to PEHO syndrome are currently unclear. Studies of the human zinc finger HIT-type containing protein 3 homolog in budding yeast (Hit1) revealed that this protein is critical for formation of small nucleolar ribonucleoprotein complexes that are required for rRNA processing and 2'-O-methylation. Here, we use budding yeast as a model system to reveal the basis for the molecular pathogenesis of PEHO syndrome. We show that missense mutations modeling those found in PEHO syndrome patients cause a decrease in steady-state Hit1 protein levels, a significant reduction of box C/D snoRNA levels, and subsequent defects in rRNA processing and altered cellular translation. Using RiboMethSeq analysis of rRNAs isolated from actively translating ribosomes, we reveal site-specific changes in the rRNA modification pattern of PEHO syndrome mutant yeast cells. Our data suggest that PEHO syndrome is a ribosomopathy and reveal potential new aspects of the molecular basis of this disease in translation dysregulation.
蛋白质合成的调控对于所有细胞中的基因表达控制至关重要。核糖体是负责翻译细胞蛋白的核糖核蛋白机器。核糖体的产生、功能或调节缺陷对细胞有害，并导致人类疾病，如进行性脑病变伴水肿、高振幅失律和视神经萎缩（PEHO）综合征。PEHO 综合征是一种毁灭性的神经发育障碍，由 ZNHIT3 基因的突变引起，该基因编码一种进化上保守的核蛋白。ZNHIT3 突变导致 PEHO 综合征的确切机制目前尚不清楚。对芽殖酵母（Hit1）中人类锌指 HIT 型含蛋白 3 同源物的研究表明，该蛋白对于小核仁核糖核蛋白复合物的形成至关重要，这些复合物是 rRNA 加工和 2'-O-甲基化所必需的。在这里，我们使用芽殖酵母作为模型系统来揭示 PEHO 综合征的分子发病机制的基础。我们发现，模拟 PEHO 综合征患者中发现的错义突变导致稳态 Hit1 蛋白水平降低，框 C/D snoRNA 水平显著降低，随后 rRNA 加工缺陷和细胞翻译改变。使用来自活跃翻译核糖体分离的 rRNA 的 RiboMethSeq 分析，我们揭示了 PEHO 综合征突变酵母细胞中 rRNA 修饰模式的特异性变化。我们的数据表明，PEHO 综合征是一种核糖体病，并揭示了该疾病在翻译失调方面的分子基础的潜在新方面。
