Rps19 R67∆ mutation creates a model of Diamond-Blackfan anemia and reveals downstream mediators of p53 pathway.

Diamond-Blackfan anemia (DBA) is a rare bone marrow failure syndrome accompanied by cardiovascular, skeletal, and urogenital abnormalities. Most of the affected individuals carry mutations in ribosomal proteins, including S19 (Rps19), a part of the 40S ribosomal subunit. We developed a transgenic model harboring deletion of conserved Arg 67 in <em>RPS19</em>, which is the site of post-translational modification by protein-arginine methyl transferase family and could show that the defect in Rps19 causes phenotype in perfect overlap with the DBA including hematologic dysfunctions, hypotrophy, intrinsic anemia, severe craniofacial, skeletal, urogenital, cardiovascular, and cerebral abnormalities leading to premature lethality during the adolescence of the mouse. This DBA mouse model exhibited activation of the Trp53 signaling pathway in hematopoietic stem cells (HSCs) leading to reduced erythroid lineage development. Competitive transplantation assays using Rps19-deficient bone marrow cells confirmed that HSCs and their progeny lineages were affected while their differentiation was rescued after inactivation of the tumor suppressor Trp53 showing that the development of the DBA phenotype significantly involves non-canonical components of the p53 signaling pathway in the etiopathogenesis of DBA with the Rps19R67∆ mutation leading to the disrupted hematopoietic hierarchy starting at the stage of short-term repopulating stem cells. The activated p53 pathway was mediated by downstream molecules Zmat3, Phlda3, and Eda2r, whose overall function in the pathology of DBA involve erythroid differentiation blockade coupled with cell proliferation and survival disruption. To conclude, the new DBA model represents a powerful tool for exploring new therapeutic options for DBA.戴蒙德-布莱克范贫血（Diamond-Blackfan anemia, DBA）是一类罕见的骨髓衰竭综合征，常伴随心血管、骨骼及泌尿生殖系统异常。绝大多数受累个体存在核糖体蛋白编码基因突变，其中包括参与40S核糖体亚基组成的核糖体蛋白S19（Rps19）。本研究构建了携带<em>RPS19</em>基因保守精氨酸67位缺失的转基因模型，该位点正是蛋白质精氨酸甲基转移酶家族介导翻译后修饰的靶点。利用该模型，我们证实Rps19缺陷可引发与DBA表型高度吻合的异常：包括血液学功能障碍、发育不全、原发性贫血，以及严重的颅面部、骨骼、泌尿生殖系统、心血管及脑部异常，并可导致小鼠在青春期阶段过早死亡。该DBA小鼠模型可见造血干细胞（hematopoietic stem cells, HSCs）中Trp53信号通路激活，进而造成红系发育受阻。采用Rps19缺陷型骨髓细胞开展的竞争性移植实验证实，造血干细胞及其子代细胞谱系均受影响；而失活肿瘤抑制因子Trp53可挽救其分化缺陷，这表明DBA表型的发生发展显著依赖p53信号通路的非经典组分。携带Rps19R67∆突变可破坏始于短期重建造血干细胞阶段的造血层级结构。激活的p53通路由下游分子Zmat3、Phlda3及Eda2r介导，上述分子在DBA病理过程中的核心作用为红系分化阻滞，同时伴随细胞增殖与存活异常。综上，本新型DBA模型为探索DBA的新型治疗方案提供了强有力的研究工具。