Danilova Nadia, Bibikova Elena, Covey Todd M, Nathanson David, Dimitrova Elizabeth, Konto Yoan, Lindgren Anne, Glader Bertil, Radu Caius G, Sakamoto Kathleen M, Lin Shuo
Department of Molecular, Cell & Developmental Biology, University of California, Los Angeles, CA 90095, USA.
Department of Pediatrics, Stanford University School of Medicine, Stanford, CA 94305-5208, USA.
Dis Model Mech. 2014 Jul;7(7):895-905. doi: 10.1242/dmm.015495. Epub 2014 May 8.
Ribosomal biogenesis involves the processing of pre-ribosomal RNA. A deficiency of some ribosomal proteins (RPs) impairs processing and causes Diamond Blackfan anemia (DBA), which is associated with anemia, congenital malformations and cancer. p53 mediates many features of DBA, but the mechanism of p53 activation remains unclear. Another hallmark of DBA is the upregulation of adenosine deaminase (ADA), indicating changes in nucleotide metabolism. In RP-deficient zebrafish, we found activation of both nucleotide catabolism and biosynthesis, which is consistent with the need to break and replace the faulty ribosomal RNA. We also found upregulation of deoxynucleotide triphosphate (dNTP) synthesis - a typical response to replication stress and DNA damage. Both RP-deficient zebrafish and human hematopoietic cells showed activation of the ATR/ATM-CHK1/CHK2/p53 pathway. Other features of RP deficiency included an imbalanced dNTP pool, ATP depletion and AMPK activation. Replication stress and DNA damage in cultured cells in non-DBA models can be decreased by exogenous nucleosides. Therefore, we treated RP-deficient zebrafish embryos with exogenous nucleosides and observed decreased activation of p53 and AMPK, reduced apoptosis, and rescue of hematopoiesis. Our data suggest that the DNA damage response contributes to p53 activation in cellular and zebrafish models of DBA. Furthermore, the rescue of RP-deficient zebrafish with exogenous nucleosides suggests that nucleoside supplements could be beneficial in the treatment of DBA.
核糖体生物合成涉及前核糖体RNA的加工。一些核糖体蛋白（RP）的缺陷会损害加工过程，并导致钻石黑范贫血（DBA），该疾病与贫血、先天性畸形和癌症相关。p53介导了DBA的许多特征，但p53激活的机制仍不清楚。DBA的另一个标志是腺苷脱氨酶（ADA）的上调，这表明核苷酸代谢发生了变化。在缺乏RP的斑马鱼中，我们发现核苷酸分解代谢和生物合成均被激活，这与打破并替换有缺陷的核糖体RNA的需求一致。我们还发现脱氧核苷酸三磷酸（dNTP）合成上调——这是对复制应激和DNA损伤的典型反应。缺乏RP的斑马鱼和人类造血细胞均显示ATR/ATM-CHK1/CHK2/p53通路被激活。RP缺乏的其他特征包括dNTP库失衡、ATP消耗和AMPK激活。在非DBA模型的培养细胞中，外源性核苷可降低复制应激和DNA损伤。因此，我们用外源性核苷处理缺乏RP的斑马鱼胚胎，观察到p53和AMPK的激活减少、凋亡减少以及造血功能得到挽救。我们的数据表明，在DBA的细胞和斑马鱼模型中，DNA损伤反应促成了p53的激活。此外，用外源性核苷挽救缺乏RP的斑马鱼表明核苷补充剂可能对DBA的治疗有益。
