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bioRxiv · 10.64898/2026.06.29.735367

A Metabolic Enzyme, Pyruvate Carboxylase, Functions as a Sequence-Selective Small RNA Sensor for Antiviral Immunity

Kariyawasam, U.·Goswami, S.·Hao, M.·Wiscovitch-Russo, R.·Chen, Q.·Yang, J.·Qiu, J.·Marquez, M.·Sui, H.·Chang, W.·Imamichi, T.
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Abstract

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<0.001), whereas PC or LGP2 depletion by siRNAs markedly attenuated this response (50-100-fold reduction, p<0.01). Reconstitution of PC and LGP2 in deficient HEK293 cells restored miRTC14-driven IFN induction. Notably, IFN activation depended on sequence features at the duplex termini. However, PC-miRTC14-LGP2 axis activates TBK1-dependent phosphorylation of IRF3/7, similarly to canonical RNA sensors (RIG-I/MDA5), but this process induced differential IFN subtype. These findings establish PC as a miRNA-binding protein and define a previously unrecognized RNA-sensing mechanism, linking metabolic enzymes to RNA sequence-dependent innate immunity. GRAPHICAL ABSTRACT O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=189 SRC="FIGDIR/small/735367v2_ufig1.gif" ALT="Figure 1"> 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

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Kariyawasam, U., Goswami, S., Hao, M., Wiscovitch-Russo, R., Chen, Q., Yang, J., Qiu, J., Marquez, M., Sui, H., Chang, W., Imamichi, T.. 2026-07-03. A Metabolic Enzyme, Pyruvate Carboxylase, Functions as a Sequence-Selective Small RNA Sensor for Antiviral Immunity. https://doi.org/10.64898/2026.06.29.735367

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