Université de Paris, Institut Cochin, INSERM U1016-CNRS UMR8104, Paris, France.
Laboratory of Excellence GR-Ex, Paris, France.
Am J Hematol. 2021 Apr 1;96(4):480-492. doi: 10.1002/ajh.26104. Epub 2021 Feb 4.
Efficient erythropoiesis relies on the expression of the transferrin receptor type 2 (TFR2). In erythroid precursors, TFR2 facilitates the export of the erythropoietin receptor (EPOR) to cell surface, which ensures the survival and proliferation of erythroblasts. Although TFR2 has a crucial role in erythropoiesis regulation, its mechanism of action remains to be clarified. To understand its role better, we aimed at identifying its protein partners by mass-spectrometry after immunoprecipitation in erythroid cells. Here we report the kinase MRCKα (myotonic dystrophy kinase-related CDC42-binding kinase α) as a new partner of both TFR2 and EPOR in erythroblasts. We show that MRCKα is co-expressed with TFR2, and TFR1 during terminal differentiation and regulates the internalization of the two types of transferrin receptors. The knockdown of MRCKα by shRNA in human primary erythroblasts leads to a decreased cell surface expression of both TFR1 and TFR2, an increased cell-surface expression of EPOR, and a delayed differentiation. Additionally, knockout of Mrckα in the murine MEDEP cells also leads to a striking delay in erythropoiesis, showcasing the importance of this kinase in both species. Our data highlight the importance of MRCKα in the regulation of erythropoiesis.
有效的红细胞生成依赖于转铁蛋白受体 2（TFR2）的表达。在红细胞前体中，TFR2 促进促红细胞生成素受体（EPOR）向细胞表面的输出，这确保了红细胞的存活和增殖。尽管 TFR2 在红细胞生成调节中具有关键作用，但它的作用机制仍有待阐明。为了更好地了解其作用，我们旨在通过免疫沉淀后进行质谱分析来鉴定其在红细胞中的蛋白质伴侣。在这里，我们报告肌球蛋白轻链激酶相关 CDC42 结合激酶 α（MRCKα）作为红细胞中 TFR2 和 EPOR 的新伴侣。我们表明，MRCKα与 TFR2 和 TFR1 在终末分化过程中共同表达，并调节两种转铁蛋白受体的内化。在人原代红细胞中通过 shRNA 敲低 MRCKα 会导致 TFR1 和 TFR2 的细胞表面表达减少、EPOR 的细胞表面表达增加以及分化延迟。此外，在鼠 MEDEP 细胞中敲除 Mrckα 也会导致红细胞生成明显延迟，这突显了该激酶在两种物种中的重要性。我们的数据强调了 MRCKα 在红细胞生成调节中的重要性。
