NCOA4 Regulates Iron Recycling and Responds to Hepcidin Activity and Lipopolysaccharide in Macrophages

Abstract

Macrophages, via erythrophagocytosis, recycle iron from effete erythrocytes to newly developing red blood cells. Conversion of potentially cytotoxic levels of iron from its heme into nonheme form during iron recycling is safely accomplished via coordinated regulations of cellular iron transport and homeostasis. Herein, we demonstrate the roles and regulation of NCOA4 (nuclear receptor coactivator 4)-mediated ferritinophagy in macrophages after erythrophagocytosis using the mouse macrophage cell line J774 cells. Ferritin in J774 cells increased with the rise of nonheme iron by erythrocyte ingestion and declined when total cellular iron contents subsequently decreased. NCOA4, a selective autophagic cargo receptor for ferritin, was responsible for the control of cellular ferritin and total iron contents at the later stage of erythrophagocytosis. A hepcidin analog, which limits the flux of iron through iron-recycling by inhibiting iron export at the plasma membrane, repressed NCOA4 expression and led to accumulation of ferritin in the mouse macrophages. Transcriptome analyses revealed a functional association of immune response with NCOA4-dependent gene expressions, and we confirmed repression of Ncoa4 by lipopolysaccharide (LPS) in J774 cells and the spleen of mice. Collectively, our studies indicate that NCOA4 facilitates cellular ferritin turnover and the release of iron by macrophages after erythrophagocytosis and functions as a regulatory target for molecular signals of systemic iron overload and inflammation. These identify macrophage NCOA4 as a potential therapeutic target for disorders of systemic iron dysregulation, including anemia of inflammation and hemochromatosis.

Cellular Zinc Deficiency Impairs Heme Biosynthesis in Developing Erythroid Progenitors

“…The cells were washed twice with ice-cold PBS containing 10 mM ethylenediaminetetraacetic acid (EDTA) and transferred to acid-washed tubes at the third washing step. Frozen pellets of a known number of cells were processed and analyzed at the University of Nebraska for quantitative measurements of mineral contents using inductively coupled plasma mass spectrometry (ICP-MS), as previously described [ 24 ]. Metal contents were normalized to total protein contents determined by the bicinchoninic acid (BCA) assays (Thermo Scientific, Waltham, MA, USA; #23225), cell counts, or phosphorous levels of each sample.…”

Iron-tracking strategies: Chaperones capture iron in the cytosolic labile iron pool

“…Based on mouse studies, minihepcidin can mimic the biological function of natural hepcidin and block iron export through ferroportin, making it a potential drug candidate for treatment or prevention of iron overload. Minihepcidin has been used in murine studies on iron absorption and iron homeostasis ( Guggisberg et al, 2022 ; Hanudel et al, 2022 ) and can be used in conjunction with tracer studies to produce rapid and complete inhibition of ferroportin-mediated iron efflux.…”

Ferritinophagy: research advance and clinical significance in cancers

“…In the first place, NCOA4 plays a role in cancer therapy. Studies have shown that lipopolysaccharide (LPS) can regulate ferritin conversion by inhibiting NCOA4 as a therapeutic target for cancer [ 83 ]. Powdered tetrandrine citrate (TetC), a novel highly water-soluble powdered cycloheximide salt, has strong anticancer activity not only in chronic myeloid leukemia, but also in breast cancer cells by inhibiting GPX4 expression and activation of NCOA4 to promote ferritinophagy in cancer cells inducing ferrogenic cell death [ 80 ].…”