Beyond Metabolism: Pyruvate Carboxylase Acts as a Sequence-Selective Small RNA Sensor Orchestrating Antiviral Responses

Interleukin-27 (IL-27) is an anti-HIV cytokine that induces 14 novel microRNAs (miRNAs) in primary CD4(+) T cells. We previously reported that transfection of two of these miRNA mimics, miRTC10 and miRTC14 into human primary macrophages, differentially induced interferon (IFN)-2, -8, -13, and -{lambda}1 expression. However, the mechanism underlying this activation remains unclear. Here, we demonstrate that miRTC14 does not directly target canonical IFN-regulatory genes but instead engages with pyruvate carboxylase (PC) and laboratory of genetics and physiology-2 (LGP2/DHX58) as direct binding partner proteins. Functional analysis revealed that miRTC14 transfection induces IFN expression by more than 100-fold (p View larger version (42K): org.highwire.dtl.DTLVardef@ea70d3org.highwire.dtl.DTLVardef@1953a73org.highwire.dtl.DTLVardef@305f16org.highwire.dtl.DTLVardef@1b2daff_HPS_FORMAT_FIGEXP M_FIG O_FLOATNOGraphical Abstract:C_FLOATNO microRNA sequence-dependent activation of innate immunity by pyruvate carboxylase (PC). PC-miRTC14-LGP2 axis induces TBK1 phosphorylation via an as-yet-unidentified adapter(s). The activated TBK1 (p-TBK1) subsequently phosphorylates IRF3 and/or IRF7 leading to selective IFN subtypes (IFN-2, IFN-8, IFN-13, and IFN-{lambda}1). (Created in BioRender. Kariyawasam, U. (2027) https://BioRender.com/u82s04p) C_FIG