Affinage

DHX34

Probable ATP-dependent RNA helicase DHX34 · UniProt Q14147

Length
1143 aa
Mass
128.1 kDa
Annotated
2026-06-09
9 papers in source corpus 8 papers cited in narrative 8 extracted findings
Cross-family judge vs UniProt: Affinage preferred faithfulness: 6/6 claims corpus-supported (100%)

Mechanistic narrative

Synthesis pass · prose summary of the discoveries below

DHX34 is a DExD/H-box RNA helicase that functions as an activator of nonsense-mediated mRNA decay (NMD), where it acts as a molecular scaffold coupling substrate recognition to kinase-driven mRNP remodeling (PMID:25220460, PMID:26841701). DHX34 is recruited to the SURF complex through preferential binding to hypophosphorylated UPF1, and it drives the remodeling steps that convert SURF into the decay-inducing DECID complex: enhanced UPF2 recruitment, increased UPF1 phosphorylation, and dissociation of eRF3 from UPF1 (PMID:25220460). This activity is organized across two structural units, a core domain that binds UPF1 and a C-terminal domain that binds the SMG1 kinase, such that DHX34 bridges UPF1 and SMG1 and CTD truncation abolishes SMG1 binding, UPF1 phosphorylation, and NMD activation (PMID:26841701). DHX34 also directly engages the RUVBL1-RUVBL2 AAA-ATPase ring, inducing conformational changes that stabilize a nucleotide-free, ATP-hydrolysis-down-regulated state of the RUVBL2 subunits, coupling this ATPase to NMD initiation (PMID:33205750). Its role in NMD is conserved and physiologically required: depletion in zebrafish abrogates degradation of PTC-containing mRNAs and causes developmental defects, and DHX34 acts with NBAS in a conserved negative feedback loop that regulates NMD-factor transcripts across human, zebrafish, and C. elegans (PMID:21227923, PMID:23828042). Beyond canonical NMD, DHX34 associates with the spliceosomal catalytic C complex, binds pre-mRNA at exon-intron boundaries, and regulates alternative splicing, with loss blocking erythroid and myeloid differentiation of hematopoietic progenitors (PMID:35768279).

Mechanistic history

Synthesis pass · year-by-year structured walk · 7 steps
  1. 2011 Medium

    Established that DHX34 is a bona fide NMD factor in vivo by showing its loss phenocopies core NMD machinery and stabilizes PTC-containing transcripts.

    Evidence Morpholino knockdown in zebrafish embryos with NMD reporter assays and phenotypic comparison to Upf1/Smg-5/Smg-6 morphants

    PMID:21227923

    Open questions at the time
    • Did not define the molecular step at which DHX34 acts
    • Epistasis inferred from morphant phenotype similarity rather than biochemistry
    • No human cell mechanism established
  2. 2013 Medium

    Defined the endogenous transcript scope of DHX34 action and placed it in a conserved autoregulatory feedback loop controlling NMD factor levels.

    Evidence Microarray profiling after RNAi depletion in human cells, zebrafish, and C. elegans with cross-species comparison alongside NBAS

    PMID:23828042

    Open questions at the time
    • Co-regulation with NBAS does not establish a physical complex
    • Direct vs indirect target effects not separated
    • Mechanism of feedback selectivity unknown
  3. 2014 High

    Resolved where DHX34 acts in the NMD cascade, showing it recognizes hypophosphorylated UPF1 and catalyzes the SURF-to-DECID transition.

    Evidence Co-immunoprecipitation, interaction and phosphorylation assays in human cells

    PMID:25220460

    Open questions at the time
    • Did not resolve the structural basis of UPF1 versus SMG1 engagement
    • Whether helicase ATPase activity is required not addressed
    • Order of remodeling events not fully ordered
  4. 2016 High

    Explained how DHX34 promotes UPF1 phosphorylation by defining a bipartite scaffold that bridges UPF1 and the SMG1 kinase.

    Evidence Electron microscopy of the SMG1-DHX34 complex with truncation mutants and binding/phosphorylation assays

    PMID:26841701

    Open questions at the time
    • EM resolution limits atomic interpretation of the interface
    • Role of the RNA helicase catalytic activity not defined
    • How scaffolding is regulated in time unknown
  5. 2020 High

    Identified a new biochemical partner, showing DHX34 remodels the RUVBL1-RUVBL2 ring to modulate its ATPase, proposing an energy-coupling step for NMD initiation.

    Evidence Cryo-EM, in vitro binding, cellular Co-IP, and ATPase-deficient mutants

    PMID:33205750

    Open questions at the time
    • Functional consequence of RUVBL2 ATPase down-regulation for NMD output not directly demonstrated
    • Link between RUVBL remodeling and the SURF/DECID transition not bridged
    • In-cell relevance of the nucleotide-free state untested
  6. 2022 Medium

    Extended DHX34 function beyond NMD to pre-mRNA splicing, linking it to the spliceosomal C complex and to hematopoietic differentiation.

    Evidence Spliceosomal C complex Co-IP, CLIP-seq, RNA-seq for alternative splicing, and siRNA knockdown differentiation assays in HSPCs

    PMID:35768279

    Open questions at the time
    • Whether splicing and NMD roles are mechanistically separable not resolved
    • Direct catalytic contribution to splicing not shown
    • Causal chain from splicing changes to differentiation blockade incomplete
  7. 2025 Low

    Connected DHX34 loss to innate immune activation via dsRNA accumulation and to an immunomodulatory role in tumor-associated macrophages.

    Evidence DHX34 knockdown and myeloid-restricted Dhx34 knockout in HCC cell and mouse models with dsRNA detection, effector immunoblotting, and CD8+ T cell assays

    PMID:40592235 PMID:41389669

    Open questions at the time
    • Pathway inferred from downstream effectors without direct reconstitution
    • No molecular mechanism for CX3CL1 regulation identified
    • Source and regulation of accumulating dsRNA not defined

Open questions

Synthesis pass · forward-looking unresolved questions
  • How the helicase ATPase activity, RUVBL ring remodeling, splicing engagement, and NMD scaffolding are integrated into a single catalytic cycle remains unresolved.
  • No unified model linking DHX34 ATPase, RUVBL coupling, and DECID formation
  • Whether NMD and splicing functions use shared or distinct domains unknown
  • Physiological substrate determinants of DHX34 recruitment undefined

Mechanism profile

Synthesis pass · controlled-vocabulary classification · explore literature graph →
Molecular activity
GO:0003723 RNA binding 3 GO:0060090 molecular adaptor activity 2 GO:0098772 molecular function regulator activity 2 GO:0140098 catalytic activity, acting on RNA 1
Localization
GO:0005634 nucleus 1 GO:0005829 cytosol 1
Pathway
R-HSA-8953854 Metabolism of RNA 3 R-HSA-74160 Gene expression (Transcription) 1
Partners
NBASRUVBL1RUVBL2SMG1UPF1UPF2
Complex memberships
SURF/DECID complexspliceosomal C complex

Evidence

Reading pass · 8 per-paper findings extracted from the source corpus
Year Finding Method Journal Conf PMIDs
2014 DHX34 is recruited to the SURF complex (SMG1, UPF1, eRF1, eRF3) via preferential interaction with hypophosphorylated UPF1, and promotes mRNP remodeling including enhanced recruitment of UPF2, increased UPF1 phosphorylation, and dissociation of eRF3 from UPF1, thereby converting the SURF complex to the decay-inducing complex (DECID) to activate NMD. Co-immunoprecipitation, molecular interaction assays, phosphorylation assays in human cells Cell reports High 25220460
2016 DHX34 comprises two distinct structural units: a core domain that binds UPF1 and a C-terminal domain (CTD) that binds the SMG1 kinase. DHX34 acts as a scaffold bridging UPF1 and SMG1, and truncation of the CTD abrogates SMG1 binding, UPF1 phosphorylation, and NMD activation without affecting UPF1 binding. Electron microscopy of SMG1-DHX34 complex, truncation mutants, binding and phosphorylation assays Nature communications High 26841701
2020 DHX34 directly interacts with the RUVBL1-RUVBL2 AAA-ATPase hetero-hexameric ring in vitro and in cells. Cryo-EM reveals DHX34 induces extensive conformational changes in the N-termini of every RUVBL2 subunit, stabilizing a nucleotide-free conformation that down-regulates ATP hydrolysis exclusively in RUVBL2 subunits, proposing a coupling role between RUVBL1-RUVBL2 ATPase activity and NMD initiation. Cryo-EM, in vitro binding assays, co-immunoprecipitation in cells, ATPase-deficient mutants eLife High 33205750
2011 Depletion of zebrafish Dhx34 results in severe developmental defects and reduced embryonic viability, and abrogates degradation of PTC-containing mRNAs, placing Dhx34 in the same NMD pathway as Upf1, Smg-5, and Smg-6 (genetic epistasis via similar morphant phenotypes). Morpholino knockdown in zebrafish embryos, NMD reporter assays, phenotypic comparison to Upf1/Smg-5/Smg-6 morphants Nucleic acids research Medium 21227923
2013 DHX34 and NBAS co-regulate a large number of endogenous NMD targets in human cells, zebrafish, and C. elegans, and participate in a conserved NMD negative feedback regulatory loop in which transcripts encoding NMD factors themselves are sensitive to DHX34 and NBAS depletion. Microarray expression profiling after RNAi depletion in human cells, zebrafish embryos, and C. elegans; cross-species comparison Nucleic acids research Medium 23828042
2022 DHX34 is associated with the human spliceosomal catalytic C complex and, as mapped by CLIP, binds preferentially to pre-mRNAs at exon-intron boundaries, regulating a large number of alternative splicing events in mammalian cells. Loss of DHX34 in hematopoietic stem/progenitor cells causes differentiation blockade of both erythroid and myeloid lineages. Co-immunoprecipitation with spliceosomal C complex, CLIP-seq mapping of endogenous binding sites, RNA-seq for alternative splicing, siRNA knockdown in HSPCs with differentiation assays RNA (New York, N.Y.) Medium 35768279
2025 DHX34 depletion in HCC cells triggers accumulation of double-stranded RNA (dsRNA), which activates cytosolic RNA-sensing pathway effectors MAVS, p-IKK, and p-IRF3, leading to type I interferon response and CD8+ T cell activation. DHX34 knockdown in HCC cell lines and mouse tumor models, dsRNA detection, western blot for MAVS/p-IKK/p-IRF3, flow cytometry for CD8+ T cells Neoplasia (New York, N.Y.) Low 40592235
2025 In tumor-associated macrophages, DHX34 suppresses CX3CL1 (fractalkine) expression and release; myeloid-restricted Dhx34 deletion increases CX3CL1 output, augmenting influx of CX3CR1+ CD8+ T cells into HCC tumors. Myeloid-restricted conditional Dhx34 knockout mouse model, qPCR/ELISA/immunoblotting for CX3CL1, Transwell CD8+ T cell migration assay International immunopharmacology Low 41389669

Source papers

Stage 0 corpus · 9 papers · ranked by NIH iCite citations
Year Title Journal Citations PMID
2013 DHX34 and NBAS form part of an autoregulatory NMD circuit that regulates endogenous RNA targets in human cells, zebrafish and Caenorhabditis elegans. Nucleic acids research 76 23828042
2014 The RNA helicase DHX34 activates NMD by promoting a transition from the surveillance to the decay-inducing complex. Cell reports 62 25220460
2011 Dhx34 and Nbas function in the NMD pathway and are required for embryonic development in zebrafish. Nucleic acids research 56 21227923
2016 The RNA helicase DHX34 functions as a scaffold for SMG1-mediated UPF1 phosphorylation. Nature communications 40 26841701
2022 A dual role for the RNA helicase DHX34 in NMD and pre-mRNA splicing and its function in hematopoietic differentiation. RNA (New York, N.Y.) 14 35768279
2020 Regulation of RUVBL1-RUVBL2 AAA-ATPases by the nonsense-mediated mRNA decay factor DHX34, as evidenced by Cryo-EM. eLife 14 33205750
2025 DHX34 deficiency triggers tumor-intrinsic immunity via a dsRNA-mediated type I interferon pathway activation in HCC. Neoplasia (New York, N.Y.) 2 40592235
2025 Macrophage DHX34 as a negative regulator of the CX3CL1-CX3CR1 axis and CD8+ T-cell infiltration in hepatocellular carcinoma. International immunopharmacology 1 41389669
2025 Environmental cadmium exposure promotes lung cancer via DHX34: A molecular toxicology perspective. Ecotoxicology and environmental safety 0 40974667

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