Ribonuclease inhibitor 1 regulates erythropoiesis by controlling GATA1 translation
Vijaykumar Chennupati, … , Trang Hoang, Ramanjaneyulu Allam
Vijaykumar Chennupati, … , Trang Hoang, Ramanjaneyulu Allam
Published February 6, 2018
Citation Information: J Clin Invest. 2018;128(4):1597-1614. https://doi.org/10.1172/JCI94956.
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Research Article Development Hematology

Ribonuclease inhibitor 1 regulates erythropoiesis by controlling GATA1 translation

Abstract

Ribosomal proteins (RP) regulate specific gene expression by selectively translating subsets of mRNAs. Indeed, in Diamond-Blackfan anemia and 5q– syndrome, mutations in RP genes lead to a specific defect in erythroid gene translation and cause anemia. Little is known about the molecular mechanisms of selective mRNA translation and involvement of ribosomal-associated factors in this process. Ribonuclease inhibitor 1 (RNH1) is a ubiquitously expressed protein that binds to and inhibits pancreatic-type ribonucleases. Here, we report that RNH1 binds to ribosomes and regulates erythropoiesis by controlling translation of the erythroid transcription factor GATA1. Rnh1-deficient mice die between embryonic days E8.5 and E10 due to impaired production of mature erythroid cells from progenitor cells. In Rnh1-deficient embryos, mRNA levels of Gata1 are normal, but GATA1 protein levels are decreased. At the molecular level, we found that RNH1 binds to the 40S subunit of ribosomes and facilitates polysome formation on Gata1 mRNA to confer transcript-specific translation. Further, RNH1 knockdown in human CD34+ progenitor cells decreased erythroid differentiation without affecting myelopoiesis. Our results reveal an unsuspected role for RNH1 in the control of GATA1 mRNA translation and erythropoiesis.

Authors

Vijaykumar Chennupati, Diogo F.T. Veiga, Kendle M. Maslowski, Nicola Andina, Aubry Tardivel, Eric Chi-Wang Yu, Martina Stilinovic, Cedric Simillion, Michel A. Duchosal, Manfredo Quadroni, Irene Roberts, Vijay G. Sankaran, H. Robson MacDonald, Nicolas Fasel, Anne Angelillo-Scherrer, Pascal Schneider, Trang Hoang, Ramanjaneyulu Allam

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Figure 7

RNH1 deficiency decreases erythroid differentiation and GATA1 protein levels in K562 cell.

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RNH1 deficiency decreases erythroid differentiation and GATA1 protein le...
(A) Total protein lysates of WT and RNH1-KO K562 cells were analyzed by Western blot with the indicated antibodies. K562 cells were positive for BCR-ABL oncogene. Blots are representative of 3 independent experiments. (B) qRT-PCR analysis for GATA1 mRNA levels in K562 cells, normalized to 18S rRNA expression. Data are shown as mean ± SD and are representative of 3 independent experiments. (C) Number of benzidine-positive K562 cells. Data are shown as mean ± SD and are representative of 3 independent experiments. (D) K562 cells were treated with hemin (25 μM) for 3 days and analyzed for the presence of benzidine-positive cells. Data are shown as mean ± SD and are representative of 3 independent experiments. Original magnification ×200. (E) Polysome profiles for WT and RNH1-KO K562 cells. Data are representative of 3 independent experiments. (F) qRT-PCR analysis for indicated mRNAs in monosome and polysome fractions derived from WT and RNH1-KO K562 cells, normalized to 18S rRNA expression. Data are shown as mean ± SD and are representative of 3 independent experiments. P values were determined by 2-tailed t test.