NF-E2 p45 Is Important for Establishing Normal Function of Platelets

Abstract

NF-E2 is a heterodimeric transcription factor consisting of p45 and small Maf subunits. Since p45^−/− mice display severe thrombocytopenia, p45 is recognized as a critical regulator of platelet production from megakaryocytes. To identify direct p45 target genes in megakaryocytes, we used chromatin immunoprecipitation (ChIP) sequencing to analyze the genome-wide chromatin occupancy of p45 in primary megakaryocytes. p45 target gene candidates obtained from the analysis are implicated in the production and function of platelets. Two of these genes, Selp and Myl9, were verified as direct p45 targets through multiple approaches. Since P-selectin, encoded by Selp, plays a critical role in platelet function during thrombogenesis, we tested whether p45 determines the intrinsic reactivity and potency of platelets generated from megakaryocytes. Mice expressing a hypomorphic p45 mutant instead of wild-type p45 in megakaryocytes (p45^−/−:ΔNTD-Tg mice) displayed platelet hypofunction accompanied by mild thrombocytopenia. Furthermore, lung metastasis of melanoma cells, which requires platelet activation, was repressed in p45^−/−:ΔNTD-Tg mice compared to control mice, validating the impaired function of platelets produced from p45^−/−:ΔNTD-Tg megakaryocytes. By activating genes in megakaryocytes that mediate platelet production and function, p45 determines the quantity and quality of platelets.

SUPPLEMENTAL MATERIAL

Supplemental material for this article may be found at http://dx.doi.org/10.1128/MCB.01274-12.

ACKNOWLEDGMENTS

We thank Shogo Yamamoto and Shuichi Tsutsumi for support in deep sequencing. We also thank Kyowa Hakko Kirin, Co. Ltd., for providing recombinant TPO and the Biomedical Research Core of the Tohoku University Graduate School of Medicine for technical support. We particularly appreciate the assistance of Eriko Naganuma with mouse breeding.

This work was supported by NIH grant DK50107 (E.H.B.), NWO grant 863.09.012 (L.G.), Grants-in-Aid for Scientific Research (M.Y. and H.M.) from the JSPS, Grants-in-Aid for Scientific Research on Innovative Areas (M.Y. and H.M.) from the MEXT, the Tohoku University Global COE for the Conquest of Signal Transduction Diseases with Network Medicine (M.Y.), the Core Research for Evolutional Science and Technology from the JST (M.Y. and H.M.), a research grant from Tohoku University International Advanced Research and Education Organization (R.F.), a research resident fellowship from the Foundation for Promotion of Cancer Research (Japan) for the 3rd Term Comprehensive 10-Year Strategy for Cancer Control (H.S.), and a research grant from the Princess Takamatsu Cancer Research Fund (09-24118) (H.M.).