Pratt Samia L, Zarate-Mendez Mariana, Koludarova Lidiia, Jansson Sonja, Airavaara Mikko, Hlushchuk Irena, Coleman David, Heffner Caleb, Horvath Rita, Battersby Brendan J, Burgess Robert W
The Jackson Laboratory, Bar Harbor, ME 04609, USA.
Neuroscience Ph.D. Program, Graduate School of Biomedical Science, Tufts University, Boston, MA 02111, USA.
Dis Model Mech. 2025 May 1;18(5). doi: 10.1242/dmm.052120. Epub 2025 Jun 2.
Mitochondrial translation release factor in rescue (MTRFR) catalyzes a termination step in protein synthesis, facilitating release of the nascent chain from mitoribosomes. Pathogenic variants in MTRFR cause MTRFR deficiency and are loss-of-function variants. Here, we tested gene replacement as a possible therapeutic strategy. A truncating mutation (K155*) was generated in mice; however, homozygotes die embryonically whereas mice heterozygous for this K155* allele are normal. We also generated transgenic strains expressing either wild-type human MTRFR or a partially functional MTRFR. Despite dose-dependent phenotypes from overexpression in vitro, neither transgene caused adverse effects in vivo. In K155* homozygous mice, the wild-type MTRFR transgene completely rescued the phenotype with only one copy present, whereas the mutant transgene rescued less efficiently. Detailed evaluation of mice rescued with the wild-type MTRFR transgene revealed no abnormalities. In human induced pluripotent stem cell (hiPSC)-derived knockdown neurons, mitochondrial phenotypes were corrected by AAV9-mediated delivery of MTRFR. Thus, we find no toxicity from truncated gene products or overexpression of MTRFR in vivo, and expression of MTRFR corrects phenotypes in both mouse and hiPSC models.
线粒体翻译释放因子挽救蛋白（MTRFR）催化蛋白质合成中的终止步骤，促进新生链从线粒体核糖体上释放。MTRFR中的致病变体导致MTRFR缺乏，且为功能丧失变体。在此，我们测试了基因替代作为一种可能的治疗策略。在小鼠中产生了一种截短突变（K155*）；然而，纯合子在胚胎期死亡，而携带该K155等位基因的杂合小鼠是正常的。我们还生成了表达野生型人MTRFR或部分功能性MTRFR的转基因品系。尽管在体外过表达呈现剂量依赖性表型，但两种转基因在体内均未引起不良反应。在K155纯合小鼠中，野生型MTRFR转基因仅存在一个拷贝时就完全挽救了表型，而突变转基因的挽救效率较低。对用野生型MTRFR转基因挽救的小鼠进行的详细评估未发现异常。在人诱导多能干细胞（hiPSC）衍生的基因敲低神经元中，通过AAV9介导的MTRFR递送纠正了线粒体表型。因此，我们发现在体内截短的基因产物或MTRFR过表达均无毒性，且MTRFR的表达在小鼠和hiPSC模型中均纠正了表型。
