Data_Sheet_1_Tpr Deficiency Disrupts Erythroid Maturation With Impaired Chromatin Condensation in Zebrafish Embryogenesis.PDF

Vertebrate erythropoiesis involves nuclear and chromatin condensation at the early stages of terminal differentiation, which is a unique process to distinguish mature erythrocytes from erythroblasts. However, the underlying mechanisms of chromatin condensation during erythrocyte maturation remain elusive. Here, we reported a novel zebrafish mutantcas7 with erythroid maturation deficiency. Positional cloning showed that a single base mutation in tprb gene, which encodes nucleoporin translocated promoter region (Tpr), is responsible for the disrupted erythroid maturation and upregulation of erythroid genes, including ae1-globin and be1-globin. Further investigation revealed that deficient erythropoiesis in tprbcas7 mutant was independent on HIF signaling pathway. The proportion of euchromatin was significantly increased, whereas the percentage of heterochromatin was markedly decreased in tprbcas7 mutant. In addition, TPR knockdown in human K562 cells also disrupted erythroid differentiation and dramatically elevated the expression of globin genes, which suggests that the functions of TPR in erythropoiesis are highly conserved in vertebrates. Taken together, this study revealed that Tpr played vital roles in chromatin condensation and gene regulation during erythroid maturation in vertebrates.

脊椎动物红细胞生成（erythropoiesis）在终末分化早期会经历细胞核与染色质浓缩过程，这是区分成熟红细胞与成红细胞（erythroblasts）的特有生物学过程。然而，红细胞成熟过程中染色质浓缩的潜在分子机制仍未明确。本研究报道了一种具有红细胞成熟缺陷的新型斑马鱼突变体cas7。位置克隆结果显示，编码核孔蛋白易位启动子区域（Tpr）的tprb基因发生单碱基突变，这是导致红细胞成熟受损以及ae1-珠蛋白、be1-珠蛋白等红细胞基因表达上调的原因。进一步研究表明，tprb^cas7突变体的红细胞生成缺陷不依赖于缺氧诱导因子（HIF）信号通路。在tprb^cas7突变体中，常染色质（euchromatin）的占比显著升高，而异染色质（heterochromatin）的占比则明显降低。此外，在人K562细胞中敲低TPR也会破坏红细胞分化过程，并显著上调珠蛋白基因的表达，这表明TPR在红细胞生成中的功能在脊椎动物中高度保守。综上，本研究揭示了Tpr在脊椎动物红细胞成熟过程中，对染色质浓缩与基因调控发挥关键作用。