Quantitative proteomics and RNA-sequencing of mouse liver endothelial cells identify novel regulators of BMP6 by iron
Allison L. Fisher,
Chia-Yu Wang,
Yang Xu,
Sydney Phillips,
Joao A. Paulo,
Beata Małachowska,
Xia Xiao,
Wojciech Fendler,
Joseph D. Mancias,
Jodie L. Babitt
Affiliations
Allison L. Fisher
Nephrology Division and Endocrine Unit, Massachusetts General Hospital, Harvard Medical School, Boston, MA, USA
Chia-Yu Wang
Nephrology Division and Endocrine Unit, Massachusetts General Hospital, Harvard Medical School, Boston, MA, USA
Yang Xu
Nephrology Division and Endocrine Unit, Massachusetts General Hospital, Harvard Medical School, Boston, MA, USA
Sydney Phillips
Nephrology Division and Endocrine Unit, Massachusetts General Hospital, Harvard Medical School, Boston, MA, USA
Joao A. Paulo
Department of Cell Biology, Harvard Medical School, Boston, MA, USA
Beata Małachowska
Department of Biostatistics and Translational Medicine, Medical University of Lodz, Lodz, Poland; Department of Radiation Oncology, Albert Einstein College of Medicine, NYC, NY, USA
Xia Xiao
Nephrology Division and Endocrine Unit, Massachusetts General Hospital, Harvard Medical School, Boston, MA, USA
Wojciech Fendler
Department of Biostatistics and Translational Medicine, Medical University of Lodz, Lodz, Poland; Department of Radiation Oncology, Dana-Farber Cancer Institute, Boston, MA, USA
Joseph D. Mancias
Department of Radiation Oncology, Dana-Farber Cancer Institute, Boston, MA, USA
Jodie L. Babitt
Nephrology Division and Endocrine Unit, Massachusetts General Hospital, Harvard Medical School, Boston, MA, USA; Corresponding author
Summary: Hepcidin is the master hormone governing systemic iron homeostasis. Iron regulates hepcidin by activating bone morphogenetic protein (BMP)6 expression in liver endothelial cells (LECs), but the mechanisms are incompletely understood. To address this, we performed proteomics and RNA-sequencing on LECs from iron-adequate and iron-loaded mice. Gene set enrichment analysis identified transcription factors activated by high iron, including Nrf-2, which was previously reported to contribute to BMP6 regulation, and c-Jun. Jun (encoding c-Jun) knockdown blocked Bmp6 but not Nrf-2 pathway induction by iron in LEC cultures. Chromatin immunoprecipitation of mouse livers showed iron-dependent c-Jun binding to predicted sites in Bmp6 regulatory regions. Finally, c-Jun inhibitor blunted induction of Bmp6 and hepcidin, but not Nrf-2 activity, in iron-loaded mice. However, Bmp6 and iron parameters were unchanged in endothelial Jun knockout mice. Our data suggest that c-Jun participates in iron-mediated BMP6 regulation independent of Nrf-2, though the mechanisms may be redundant and/or multifactorial.
