{"type": "root", "children": [{"type": "p", "children": [{"type": "t", "text": "\nThe current body of literature extensively documents the central roles of iron‐regulatory proteins (IRPs) in maintaining iron homeostasis. IRP1 and IRP2 post‐transcriptionally modulate the expression of key iron metabolism proteins by binding to conserved iron‐responsive elements (IREs) contained in target mRNAs. IRP1 uniquely functions in a bifunctional manner—cycling between a [4Fe‐4S] cluster–containing aconitase form and an IRE‐binding form that is largely insensitive to dynamic iron fluctuations—whereas IRP2, which does not assemble an Fe-S cluster, remains a constitutive RNA binder. Together, these mechanisms ensure basal regulation of proteins governing iron uptake, storage, and export."}, {"type": "fg", "children": [{"type": "fg_fs", "start_ref": "1", "end_ref": "5"}]}, {"type": "t", "text": "\n"}]}, {"type": "t", "text": "\n\n"}, {"type": "p", "children": [{"type": "t", "text": "\nThese regulatory proteins not only coordinate cellular iron levels but also govern diverse physiological processes. Their activity modulates erythropoiesis via control of hypoxia-inducible factor 2α translation and erythropoietin synthesis, and they play crucial roles in intestinal iron absorption and neuronal iron metabolism. Disruption of IRP functions has been linked to conditions as varied as pulmonary hypertension, neurodegeneration, and Friedreich ataxia–like syndromes, underscoring the broad impact of iron-sensing and -regulatory pathways in both systemic physiology and disease."}, {"type": "fg", "children": [{"type": "fg_fs", "start_ref": "6", "end_ref": "14"}]}, {"type": "t", "text": "\n"}]}, {"type": "t", "text": "\n\n"}, {"type": "p", "children": [{"type": "t", "text": "\nBeyond their canonical roles in post‐transcriptional iron regulation, IRPs contribute to mitochondrial function, cellular responses to oxidative/nitrosative stress, and innate immune defense. Their modulation is linked to the maintenance of iron–sulfur cluster biogenesis, adjustments in TCA cycle flux, and the regulation of signaling pathways during stress or inflammation. Notably, while these studies collectively provide comprehensive insights into the IRP/IRE regulatory network, none of the provided abstracts mention or address the function of MIR4274. Therefore, any putative role for MIR4274 in the context of iron metabolism remains to be determined, and future studies will be required to elucidate whether—and how—this microRNA might interface with the IRP-mediated framework of iron homeostasis."}, {"type": "fg", "children": [{"type": "fg_fs", "start_ref": "15", "end_ref": "24"}]}, {"type": "t", "text": "\n"}]}, {"type": "rg", "children": [{"type": "r", "ref": 1, "children": [{"type": "t", "text": "Esther G Meyron-Holtz, Manik C Ghosh, Kazuhiro Iwai, et al. 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