{"type": "root", "children": [{"type": "p", "children": [{"type": "t", "text": "\n Accumulating evidence indicates that eIF4E2 (also known as 4EHP) is a specialized cap‐binding protein that diverges significantly from the canonical eIF4E in both structure and function. Unlike eIF4E, eIF4E2 binds the mRNA 5′ cap with lower affinity and is uniquely deployed under stress conditions such as hypoxia to reprogram cap‐dependent translation. In hypoxic tumor microenvironments, cancer cells switch from an eIF4E‐mediated translation program to eIF4E2‐directed synthesis of selected proteins that support cell survival, invasiveness, and the formation of a hypoxic core."}, {"type": "fg", "children": [{"type": "fg_f", "ref": "1"}]}, {"type": "t", "text": " In addition, eIF4E2 functions as a translational repressor. It is recruited by RNA‐binding and regulatory proteins such as tristetraprolin and TNRC6A to displace eIF4E from the cap, thereby downregulating the synthesis of specific mRNAs – a mechanism integral to processes such as nonsense-mediated quality control and inflammation regulation."}, {"type": "fg", "children": [{"type": "fg_f", "ref": "3"}]}, {"type": "t", "text": " Its interaction with partners like GIGYF2 and EDF1 further facilitates the selective translational repression of aberrant mRNAs, ensuring translational fidelity under both basal and stress conditions."}, {"type": "fg", "children": [{"type": "fg_f", "ref": "5"}]}, {"type": "t", "text": " Structural studies have revealed that the unusual cap-binding surface of eIF4E2—as compared to eIF4E—is critical for these regulatory functions, and alternative transcript variants may further modulate its activity."}, {"type": "fg", "children": [{"type": "fg_f", "ref": "7"}]}, {"type": "t", "text": " Moreover, aberrant expression and genetic alterations in the EIF4E2 gene are linked to poor prognosis in various cancers including non–small cell lung cancer and uveal melanoma, while neuronal studies implicate eIF4E2 in regulating synaptic plasticity and behavior, underscoring its broad biological significance."}, {"type": "fg", "children": [{"type": "fg_fs", "start_ref": "9", "end_ref": "11"}]}, {"type": "t", "text": " Finally, the incorporation of eIF4E2 into alternative translation initiation complexes in vertebrates illustrates its evolutionary gain-of-function that allows cells to adapt protein synthesis in response to environmental cues."}, {"type": "fg", "children": [{"type": "fg_fs", "start_ref": "12", "end_ref": "14"}]}, {"type": "t", "text": " Collectively, these studies demonstrate that eIF4E2 plays a central role in modulating the translational landscape during stress responses and in maintaining cellular homeostasis through both activation of selective protein synthesis and repression of aberrant mRNA translation."}, {"type": "fg", "children": [{"type": "fg_f", "ref": "15"}, {"type": "fg_f", "ref": "6"}, {"type": "fg_f", "ref": "4"}]}, {"type": "t", "text": "\n "}]}, {"type": "rg", "children": [{"type": "r", "ref": 1, "children": [{"type": "t", "text": "James Uniacke, J Kishan Perera, Gabriel Lachance, et al. 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