Ohtsuka Rie, Abe Yasunobu, Fujii Tomomi, Yamamoto Masahiro, Nishimura Junji, Takayanagi Ryoichi, Muta Koichiro
Department of Medicine and Bioregulatory Science, Graduate School of Medical Sciences, Kyushu University, Fukuoka, Japan.
Eur J Haematol. 2007 Aug;79(2):114-25. doi: 10.1111/j.1600-0609.2007.00870.x.
Erythropoietin (EPO) stimulates erythroid growth by enhancing the proliferation, maturation and survival of late-stage erythroid progenitor cells. However, the entire process of EPO stimulation remains undetermined. To further clarify the intracellular mechanisms by which EPO affects the growth of erythroid progenitor cells, we analyzed proteins obtained from purified human erythroid colony-forming cells (ECFCs) cultured with or without EPO, and one of the proteins apparently related with EPO stimuli was identified as mortalin (mthsp70/PBP74/Grp75/mot-2), which is a member of the heat shock protein 70 family of chaperones. The amount of mortalin mRNA in ECFCs increased in an EPO dose-dependent manner, and ECFC growth was dependent on the amount of mortalin. Furthermore, expression of mortalin in ECFCs was suppressed by a phosphatidylinositol 3-kinase inhibitor. Finally, we analyzed gene expression patterns in ECFCs cultured with or without EPO after treatment with mortalin small interfering RNA (siRNA) using a DNA microarray. When ECFCs treated with mortalin siRNA were cultured with EPO, the expression of several genes overlapped with the profile seen in control ECFCs cultured without EPO. Our data suggest that mortalin is involved in the mediation of EPO signaling and plays an important role in stimulating the growth of erythroid progenitor cells.
促红细胞生成素（EPO）通过增强晚期红系祖细胞的增殖、成熟和存活来刺激红系生长。然而，EPO刺激的整个过程仍未明确。为了进一步阐明EPO影响红系祖细胞生长的细胞内机制，我们分析了从用或不用EPO培养的纯化人红系集落形成细胞（ECFCs）中获得的蛋白质，一种明显与EPO刺激相关的蛋白质被鉴定为mortalin（mthsp70/PBP74/Grp75/mot-2），它是热休克蛋白70伴侣家族的成员。ECFCs中mortalin mRNA的量以EPO剂量依赖性方式增加，并且ECFC的生长依赖于mortalin的量。此外，磷脂酰肌醇3-激酶抑制剂可抑制ECFCs中mortalin的表达。最后，我们使用DNA微阵列分析了在用mortalin小干扰RNA（siRNA）处理后用或不用EPO培养的ECFCs中的基因表达模式。当用mortalin siRNA处理的ECFCs与EPO一起培养时，几个基因的表达与在不用EPO培养的对照ECFCs中看到的谱重叠。我们的数据表明，mortalin参与EPO信号传导的介导，并在刺激红系祖细胞生长中起重要作用。
