Enhanced alternative splicing of the FLVCR1 gene in Diamond Blackfan anemia disrupts FLVCR1 expression and function that are critical for erythropoiesis
Enhanced alternative splicing of the FLVCR1 gene in Diamond Blackfan anemia disrupts FLVCR1 expression and function that are critical for erythropoiesis
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DOI：
10.3324/haematol.13359
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发表时间：
2008-11-01
期刊：
影响因子：
--
通讯作者：
Tailor, Chetankumar S.
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文献类型：
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作者：
Rey, Michelle A.;Duffy, Simon P.;Tailor, Chetankumar S.
背景Diamond-Blackfan贫血是一种以红系祖细胞发育异常为特征的致死性先天性贫血。大约25%的患者在核糖体蛋白RPS 19中有突变，这表明Diamond-Blackfan贫血可能是由核糖体生物合成和翻译缺陷引起的。然而，目前尚不清楚这些缺陷如何特异性地破坏早期红细胞生成。最近的研究表明，逆转录病毒受体/血红素输出蛋白FLVCR 1对早期红细胞生成至关重要。FLVCR 1缺失小鼠尽管在子宫内死亡并且具有减少的骨髓和淋巴样细胞生长，但显示早期红细胞生成的破坏，并且具有与在一些Diamond-Blackfan贫血患者中发现的那些类似的颅面和肢体畸形。我们重述了钻石号Blackfan贫血的血液学特征是通过破坏人造血干细胞中的FLVCR 1而导致红细胞生成减少但骨髓生成正常。来自RPS 19基因突变阴性的Diamond-Blackfan贫血患者的富含未成熟红系细胞的CD 71（高）细胞表达FLVCR 1转录物的可变剪接同种型，其编码表达和功能被破坏的蛋白质。更重要的是，我们的研究结果表明FLVCR 1的选择性剪接在Diamond-Blackfan贫血未成熟红系细胞中显著增强。此外，我们还观察到在RPS 19下调的人K562细胞中FLVCR 1选择性剪接增强和FLVCR 1蛋白表达显著降低，其用作代表RPS 19基因突变的Diamond-Blackfan贫血的模型。我们的研究结果提示FLVCR 1转录本的选择性剪接增强和随后的FLVCR 1不足是红细胞生成缺陷的另一个促成因素在Diamond-Blackfan贫血中观察到。
BackgroundDiamond-Blackfan anemia is a fatal congenital anemia characterized by a specific disruption in erythroid progenitor cell development. Approximately 25% of patients have mutations in the ribosomal protein RPS19 suggesting that Diamond-Blackfan anemia may be caused by a defect in ribosome biogenesis and translation. However, it is unclear how these defects specifically disrupt early erythropoiesis. Recent studies have shown that the retroviral receptor/heme exporter FLVCR1 is critical for early erythropoiesis. FLVCR1 null mice, despite dying in utero and having reduced myeloid and lymphoid cell growth, show a disruption in early erythropoiesis and have craniofacial and limb deformities similar to those found in some Diamond-Blackfan anemia patients.Design and MethodsIn this study, we recapitulated the Diamond-Blackfan anemia hematologic features of reduced erythropoiesis but normal myelopoiesis by disrupting FLVCR1 in human hematopoietic stem cells.ResultsWe found that CD71(high) cells, which are enriched for immature erythroid cells, from Diamond-Blackfan anemia patients negative for RPS19 gene mutations express alternatively spliced isoforms of FLVCR1 transcript which encode proteins whose expression and function are disrupted. More importantly, our results suggest alternative splicing of FLVCR1 is significantly enhanced in Diamond-Blackfan anemia immature erythroid cells. Furthermore, we also observed enhanced FLVCR1 alternative splicing and a dramatic reduction of FLVCR1 protein expression in RPS19 down-regulated human K562 cells, which were used as a model to represent RPS19 gene mutated Diamond-Blackfan anemia.ConclusionsTaken together, our results suggest enhanced alternative splicing of FLVCR1 transcripts and subsequent FLVCR1 insufficiency as an additional contributing factor to the erythropoietic defect observed in Diamond-Blackfan anemia.