{"gene":"DDX39A","run_date":"2026-06-09T23:54:41","timeline":{"discoveries":[{"year":2006,"finding":"DDX39A (DDX39) physically interacts with ALY (an essential mRNA export factor) in vivo, and co-immunoprecipitation with mass spectrometry identified CIP29 as a main DDX39-interacting protein; CIP29 binds RNA independently and enhances the RNA unwinding activity of DDX39A. DDX39A also undergoes heavy ubiquitylation and its stability is regulated via the ubiquitin-proteasome pathway.","method":"Co-immunoprecipitation, mass spectrometry, in vivo binding assay, ubiquitylation assay","journal":"Experimental cell research","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — reciprocal Co-IP and MS in single lab, functional RNA unwinding assay included","pmids":["17196963"],"is_preprint":false},{"year":2007,"finding":"Recombinant DDX39A (DDX39-L isoform) binds RNA, hydrolyzes NTPs in an RNA-dependent manner, and unwinds double-stranded RNA bidirectionally, establishing it as a bona fide RNA helicase. DDX39A localizes to distinct punctate nuclear foci consistent with a role in RNA splicing/export.","method":"In vitro RNA binding assay, NTPase assay, RNA unwinding (helicase) assay, fluorescence microscopy","journal":"Cancer biology & therapy","confidence":"High","confidence_rationale":"Tier 1 / Moderate — direct in vitro biochemical reconstitution of helicase activity with multiple orthogonal assays in a single study","pmids":["17548965"],"is_preprint":false},{"year":2004,"finding":"DDX39A (URH49) interacts with the mRNA export factor Aly and can rescue loss of Sub2p (the yeast homolog of UAP56) in Saccharomyces cerevisiae, demonstrating functional conservation in mRNA splicing and nuclear export.","method":"Yeast complementation assay, interaction assay with Aly","journal":"Nucleic acids research","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — yeast genetic complementation plus protein interaction assay, single lab","pmids":["15047853"],"is_preprint":false},{"year":2006,"finding":"siRNA-mediated knockdown of DDX39A (URH49) alone in HeLa cells causes nuclear accumulation of poly(A)+ RNA in a speckled pattern, indicating a role in mRNA nuclear export. Simultaneous knockdown of DDX39A and UAP56 results in major reduction of reporter gene expression, loss of cytoplasmic poly(A)+ RNA, and cell death, demonstrating largely overlapping but essential functions.","method":"RNA interference (siRNA), fluorescence in situ hybridization (FISH) for poly(A)+ RNA localization","journal":"Gene","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — clean siRNA KD with direct RNA localization readout, single lab, two paralogs compared","pmids":["16949217"],"is_preprint":false},{"year":2010,"finding":"DDX39A (URH49) forms a distinct complex termed the AREX (alternative mRNA export) complex with CIP29, whereas its paralog UAP56 forms the canonical human TREX complex. These two complexes regulate distinct subsets of mRNAs genome-wide. Depletion of URH49 causes chromosome arm resolution defects and cytokinesis failure, linked to its specific target mRNAs encoding mitotic regulators.","method":"Co-immunoprecipitation, genome-wide mRNA expression analysis, siRNA knockdown with mitotic phenotyping","journal":"Molecular biology of the cell","confidence":"High","confidence_rationale":"Tier 2 / Strong — reciprocal Co-IP establishing distinct complex, genome-wide target analysis, and defined cellular phenotypes upon KD; multiple orthogonal methods","pmids":["20573985"],"is_preprint":false},{"year":2011,"finding":"DDX39A directly interacts with TRF2 via a FXLXP motif in DDX39A binding to the TREX homology domain of TRF2. DDX39A also associates with catalytically competent telomerase through hTERT interaction but does not affect telomerase activity. Overexpression of DDX39A leads to progressive telomere elongation, while shRNA-mediated depletion causes telomere shortening and DNA-damage response foci at both internal genome sites and telomeres (telomere dysfunction-induced foci).","method":"Co-immunoprecipitation, domain mapping (FXLXP motif mutagenesis), shRNA knockdown, telomere length analysis, immunofluorescence for DNA damage foci","journal":"Aging cell","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — direct binding established by Co-IP with domain mapping, functional consequences from KD and overexpression, single lab","pmids":["21388492"],"is_preprint":false},{"year":2011,"finding":"The antiviral GTPase MxA directly binds DDX39A (URH49) in vitro using purified recombinant proteins, forming a complex in the perinuclear region of infected cells. Mouse Mx1 also binds URH49/UAP56 in distinct nuclear dots, suggesting Mx proteins exert antiviral activity by interfering with the RNA helicase functions of URH49 and UAP56.","method":"Immunoprecipitation, in vitro binding assay with purified recombinant proteins, immunofluorescence/subcellular localization","journal":"The Journal of biological chemistry","confidence":"Medium","confidence_rationale":"Tier 1–2 / Moderate — in vitro direct binding with recombinant proteins plus cellular co-IP and localization; single lab","pmids":["21859714"],"is_preprint":false},{"year":2011,"finding":"DDX39A (URH49) exhibits intrinsic CRM1-independent nucleocytoplasmic shuttling activity. Mapping studies identified distinct regions for intranuclear localization (aa 81–381 of UAP56) and the C-terminus (aa 195–428) as responsible for nucleocytoplasmic shuttling, which is independent of Rae1 interaction.","method":"Shuttling assay, deletion/domain mapping, co-immunoprecipitation","journal":"PloS one","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — domain mapping with shuttling assays and functional validation, single lab","pmids":["21799930"],"is_preprint":false},{"year":2016,"finding":"Simultaneous knockdown of DDX39A and its paralog DDX39B drastically and selectively downregulates AR-V7 splice variant mRNA expression in AR-V7-positive prostate cancer cell lines, indicating that DDX39A (together with DDX39B) regulates alternative splicing to generate the AR-V7 mRNA.","method":"shRNA library screen, siRNA knockdown, RT-PCR/qPCR for AR-V7 mRNA","journal":"Biochemical and biophysical research communications","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — functional screen confirmed by targeted KD in multiple cell lines, single lab","pmids":["28025139"],"is_preprint":false},{"year":2018,"finding":"DDX39A overexpression increases nuclear β-catenin levels and upregulates Wnt/β-catenin pathway target genes in hepatocellular carcinoma cells; knockdown of TCF4 and LEF1 (Wnt/β-catenin co-activators) in DDX39A-overexpressing cells reverses this effect and reduces invasion, placing DDX39A upstream of the Wnt/β-catenin pathway.","method":"Overexpression and siRNA knockdown, Western blot for β-catenin nuclear localization, reporter assay, epistasis by co-knockdown","journal":"Cell death & disease","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — genetic epistasis via double KD, nuclear fractionation for β-catenin, single lab","pmids":["29867138"],"is_preprint":false},{"year":2020,"finding":"In the ATP-depleted state, DDX39A (URH49) forms an apo-AREX complex containing CIP29 but lacking ALYREF and the THO subcomplex, distinct from UAP56's apo-TREX complex. Upon ATP addition, the apo-AREX complex is remodeled into an ATP-TREX-like complex containing THO subcomplex, ALYREF, and CIP29. URH49-dependent mRNA export is achieved through NXF1, the same export receptor as the UAP56 pathway.","method":"Co-immunoprecipitation under ATP-depleted and ATP-replete conditions, siRNA knockdown, mRNA export assay","journal":"Biochimica et biophysica acta. Gene regulatory mechanisms","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — biochemical dissection of complex assembly states with functional validation, single lab","pmids":["31917363"],"is_preprint":false},{"year":2021,"finding":"The mammalian ecdysoneless protein (ECD) physically interacts with DDX39A and is required for mRNA nuclear export; ECD knockdown blocks mRNA export from nucleus to cytoplasm, and this block is rescued by full-length ECD but not by an ECD mutant defective in DDX39A interaction.","method":"Co-immunoprecipitation, siRNA knockdown, mRNA export assay (FISH for poly(A)+ RNA), rescue with ECD mutant","journal":"Molecular and cellular biology","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — reciprocal Co-IP and functional rescue experiment with interaction-defective mutant, single lab","pmids":["33941617"],"is_preprint":false},{"year":2023,"finding":"DDX39A is an antiviral protein against chikungunya virus (CHIKV) and other alphaviruses. Upon infection, predominantly nuclear DDX39A relocates to the cytoplasm, where it inhibits alphavirus replication independently of the canonical interferon pathway. DDX39A biochemically binds CHIKV genomic RNA at the 5' conserved sequence element (5'CSE), and this RNA structure is essential for DDX39A's antiviral activity.","method":"Genetic screen, loss-of-function (siRNA/CRISPR), RNA-binding assay (biochemical), subcellular localization (imaging), viral replication assay, structural element mapping","journal":"Molecular cell","confidence":"High","confidence_rationale":"Tier 1–2 / Strong — genetic screen validated by KO/KD, direct RNA-binding biochemistry, structural element requirement established, IFN-independent mechanism confirmed; multiple orthogonal methods","pmids":["37949067"],"is_preprint":false},{"year":2024,"finding":"DDX39A (URH49) stimulates loading of PHAX onto U snRNA in an ATP-dependent manner, thereby facilitating nuclear export of spliceosomal U snRNAs. ALYREF acts as a bridge between PHAX and UAP56/DDX39B in this reaction, revealing a protein-loading helicase activity distinct from classical RNA unwinding.","method":"In vitro reconstitution assay for ATP-dependent PHAX-RNA loading, co-immunoprecipitation, nuclear export assay","journal":"Nucleic acids research","confidence":"High","confidence_rationale":"Tier 1 / Moderate — in vitro reconstitution of ATP-dependent protein loading onto RNA; novel activity established biochemically","pmids":["39011894"],"is_preprint":false},{"year":2024,"finding":"DDX39A and DDX39B have significant but not fully redundant roles in alternative pre-mRNA splicing. DDX39A cannot complement DDX39B-specific targets such as IL7R exon 6 splicing. Cassette exons specifically dependent on DDX39B (but not DDX39A) have U-poor/C-rich polypyrimidine tracts in the upstream intron, which is a sequence determinant of DDX39B dependency.","method":"siRNA knockdown of individual and combined paralogs, RT-PCR splicing assays, sequence analysis of polypyrimidine tracts","journal":"Nucleic acids research","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — functional complementation/non-complementation experiments with specific splicing readouts, sequence feature analysis; single lab","pmids":["38801080"],"is_preprint":false},{"year":2024,"finding":"DDX39A (URH49) and UAP56 have unique structural features that determine their distinct apo-complex formation. Chimeric mutant analysis identified specific structural regions in each helicase responsible for forming the respective TREX or AREX apo-complexes, providing a molecular basis for functional divergence from their common ancestral gene Sub2.","method":"Structural comparison (crystal/structural analysis), chimeric mutant construction and functional analysis, co-immunoprecipitation","journal":"Nature communications","confidence":"High","confidence_rationale":"Tier 1–2 / Moderate — structural analysis combined with chimeric mutagenesis and functional complex formation assays; multiple orthogonal methods in single study","pmids":["38225262"],"is_preprint":false},{"year":2024,"finding":"Upon replication stress, DDX39A acts as an RNA-DNA hybrid (R-loop) resolver at stalled replication forks by unwinding fork-associated RNA-DNA hybrids (RF-RDs). DDX39A is recruited to stalled forks via association with RAD51. This unwinding facilitates regulated DNA2 nuclease access and controlled fork restart; loss of DDX39A causes excessive fork protection and confers chemoresistance in BRCA1/2-deficient cells.","method":"Co-immunoprecipitation (RAD51 association), chromatin fractionation, R-loop resolution assay, fork protection assay, siRNA knockdown with defined phenotypic readouts, genetic epistasis with BRCA1/2 deficiency","journal":"Molecular cell","confidence":"High","confidence_rationale":"Tier 1–2 / Strong — two independent papers (PMIDs 39706186 and 39706185) report the same mechanism with biochemical and genetic methods; replicated finding","pmids":["39706186","39706185"],"is_preprint":false},{"year":2024,"finding":"SNRPD2 (an Sm protein) modulates DDX39A intron retention together with HNRNPL to sustain expression of a DDX39A short variant (39A_S). This short variant mediates MYC mRNA nuclear export to maintain high MYC protein levels, and MYC in turn potentiates SNRPD2 transcription, forming a positive feedback loop.","method":"RNA-seq/splicing analysis, knockdown of SNRPD2/HNRNPL, mRNA export assay for MYC mRNA, ChIP/luciferase for MYC→SNRPD2 transcription, rescue experiments","journal":"Advanced science","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — multiple functional assays establishing pathway, single lab","pmids":["39018261"],"is_preprint":false},{"year":2024,"finding":"Erk2 phosphorylates Ddx39 on Y132 and Y138. Phosphorylation of Ddx39 by Erk2 promotes recruitment of Hat1 to acetylate H3K27 and activate differentiation genes in mouse ESCs. Ddx39 is recruited to telomeres by Trf1, where it disrupts Trf1-mediated DNA loops and suppresses alternative lengthening of telomeres (ALT); Erk2 phosphorylation of Ddx39 weakens its interaction with Trf1, releasing it from telomeres and allowing enhanced ALT activity.","method":"Co-immunoprecipitation/mass spectrometry (Erk2 substrates), Ddx39 knockout ESCs, phosphorylation site mutagenesis (Y132/Y138), ChIP for Hat1 recruitment, telomere length analysis, ALT assay","journal":"Cell death and differentiation","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — kinase substrate relationship and downstream effects established by mutagenesis and KO, single lab","pmids":["39107495"],"is_preprint":false},{"year":2024,"finding":"The C-terminal region of DDX39A (URH49) is indispensable for AREX complex formation, and a specific amino acid at the C-terminus of UAP56 (but not URH49) is critical for TREX complex formation; alanine substitution at this residue impairs complex formation and mRNA processing/export activity.","method":"Truncation and alanine substitution mutagenesis, co-immunoprecipitation, mRNA export assay","journal":"Biochemical and biophysical research communications","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — mutagenesis with functional complex and export readouts, single lab","pmids":["38377942"],"is_preprint":false},{"year":2025,"finding":"A missense variant in DDX39A (p.Lys137Gln) causes aberrant nuclear clumping of the mutant protein and prevents its interaction with the TREX component THOC1, thereby impairing TREX complex integrity. Structural modeling shows Lys137 mediates critical inter- and intra-molecular interactions. Cells from the affected proband show severe nuclear morphological abnormalities, disrupted nuclear lamina organization, and increased cell death.","method":"Patient-derived fibroblast functional studies, co-immunoprecipitation (DDX39A-K137Q vs THOC1), structural modeling, immunofluorescence for nuclear morphology, cell viability assay","journal":"Clinical genetics","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — functional studies in patient cells with Co-IP and structural modeling, single study","pmids":["40726340"],"is_preprint":false},{"year":2025,"finding":"DDX39A directly binds SP1 mRNA, stabilizing it and enhancing its translation efficiency without affecting SP1 transcription, as demonstrated by RIP-qPCR. Increased SP1 protein then binds the −223/−214 bp region of the Ku70 promoter (ChIP-qPCR, dual-luciferase assay), activating Ku70 expression and contributing to radioresistance via the non-homologous end-joining pathway.","method":"RIP-qPCR, ChIP-qPCR, dual-luciferase reporter assay, siRNA knockdown, rescue experiments, in vivo xenograft","journal":"Cellular oncology","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — RNA binding confirmed by RIP-qPCR, promoter binding by ChIP, functional rescue; single lab","pmids":["41984289"],"is_preprint":false},{"year":2026,"finding":"DDX39A stabilizes WISP1 pre-mRNA through alternative splicing regulation (identified by RNA-seq and RIP-seq), thereby activating AKT signaling. Secreted WISP1 acts as a paracrine signal promoting immunosuppressive tumor-associated macrophage polarization. The compound fluphenazine hydrochloride binds to and inhibits DDX39A, suppressing glioblastoma growth and macrophage immunosuppression.","method":"RNA-seq, RIP-seq, siRNA knockdown and overexpression, in vitro and in vivo tumor models, drug-binding assay","journal":"Oncogene","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — RIP-seq for direct RNA binding, pathway validated in vitro and in vivo, single lab","pmids":["41772197"],"is_preprint":false}],"current_model":"DDX39A (also known as URH49, DDX39, DDXL) is a DEAD-box RNA helicase with ATP-dependent RNA unwinding activity that forms a distinct mRNA export complex (AREX) with CIP29, separate from the UAP56-containing TREX complex, to mediate nuclear export of a specific subset of mRNAs via NXF1; it additionally loads PHAX onto U snRNAs to facilitate snRNA export, regulates alternative pre-mRNA splicing, resolves RNA-DNA hybrids at stalled replication forks in a RAD51-dependent manner to control DNA2-mediated fork processing, interacts with TRF2 and telomerase to modulate telomere length, is phosphorylated by Erk2 (Y132/Y138) to control ESC differentiation and ALT activity, binds specific viral RNA structures (CHIKV 5'CSE) to restrict alphavirus infection in an IFN-independent manner, and is directly targeted by the antiviral GTPase MxA, while a pathogenic K137Q variant disrupts its interaction with THOC1 and impairs TREX complex integrity causing a neurodegenerative phenotype."},"narrative":{"mechanistic_narrative":"DDX39A is an ATP-dependent DEAD-box RNA helicase that binds RNA, hydrolyzes NTPs in an RNA-dependent manner, and bidirectionally unwinds double-stranded RNA, functioning principally in nuclear mRNA and snRNA export [PMID:17548965, PMID:16949217]. It is the paralog of UAP56/DDX39B and assembles a distinct export complex, the AREX complex, with CIP29 — separate from the canonical UAP56-based TREX complex — and the two complexes regulate distinct genome-wide subsets of mRNAs; depletion of DDX39A causes chromosome arm resolution defects and cytokinesis failure linked to its mitotic-regulator target mRNAs [PMID:17196963, PMID:20573985]. Complex identity is determined by ATP state and by unique structural features of each helicase, particularly the C-terminus of DDX39A, with the apo-AREX complex remodeling into a TREX-like complex containing THO, ALYREF, and CIP29 upon ATP addition; export ultimately proceeds through the NXF1 receptor [PMID:31917363, PMID:38225262, PMID:38377942]. Beyond bulk mRNA export, DDX39A performs a protein-loading reaction, stimulating ATP-dependent loading of PHAX onto spliceosomal U snRNAs to drive their nuclear export, and contributes non-redundantly with DDX39B to alternative pre-mRNA splicing [PMID:39011894, PMID:38801080]. DDX39A also acts on genome maintenance: upon replication stress it is recruited to stalled forks via RAD51 to resolve fork-associated RNA-DNA hybrids and license regulated DNA2 nuclease access and fork restart, with loss causing excessive fork protection and chemoresistance in BRCA1/2-deficient cells [PMID:39706186, PMID:39706185]. It modulates telomere length through direct interaction with TRF2 and association with telomerase, and Erk2 phosphorylation at Y132/Y138 controls its telomeric and differentiation functions [PMID:21388492, PMID:39107495]. In antiviral defense, DDX39A relocates from nucleus to cytoplasm upon infection and restricts alphaviruses by binding the CHIKV 5' conserved sequence element in an interferon-independent manner, and is itself targeted by the antiviral GTPase MxA [PMID:21859714, PMID:37949067]. A pathogenic p.Lys137Gln variant causes nuclear clumping of the protein and abolishes its interaction with THOC1, impairing TREX integrity and producing severe nuclear morphological abnormalities and increased cell death in patient cells [PMID:40726340].","teleology":[{"year":2004,"claim":"Established that DDX39A is a functional ortholog of the yeast mRNA export helicase Sub2/UAP56, defining its baseline role in mRNA splicing and nuclear export.","evidence":"Yeast complementation of Sub2p loss and Aly interaction assay","pmids":["15047853"],"confidence":"Medium","gaps":["Did not establish whether DDX39A functions independently of UAP56 in human cells","No biochemical demonstration of helicase activity"]},{"year":2006,"claim":"Identified CIP29 as a principal DDX39A partner that stimulates its unwinding activity and showed DDX39A interacts with ALY, beginning the definition of its export-complex composition.","evidence":"Co-IP/mass spectrometry, in vivo binding, RNA unwinding stimulation, and ubiquitylation assays in human cells","pmids":["17196963"],"confidence":"Medium","gaps":["Did not yet distinguish DDX39A complexes from UAP56/TREX","Functional consequence of ubiquitylation on activity unresolved"]},{"year":2006,"claim":"Showed by RNA localization that DDX39A is required for mRNA nuclear export and that it shares essential, partly overlapping function with UAP56.","evidence":"siRNA knockdown with poly(A)+ RNA FISH in HeLa cells","pmids":["16949217"],"confidence":"Medium","gaps":["Did not identify which specific mRNAs depend on DDX39A versus UAP56","Mechanism of selectivity unaddressed"]},{"year":2007,"claim":"Confirmed DDX39A is a bona fide ATP-dependent RNA helicase, providing the biochemical foundation for all downstream activities.","evidence":"In vitro RNA binding, NTPase, and bidirectional unwinding assays with recombinant protein plus nuclear foci imaging","pmids":["17548965"],"confidence":"High","gaps":["In vitro substrate specificity relative to cellular targets not defined","Link between enzymatic activity and export not directly tested"]},{"year":2010,"claim":"Defined DDX39A as the core of a distinct AREX complex with CIP29, separate from UAP56's TREX, regulating distinct mRNA subsets and a specific mitotic function.","evidence":"Reciprocal Co-IP, genome-wide expression analysis, and siRNA knockdown with mitotic phenotyping","pmids":["20573985"],"confidence":"High","gaps":["Determinants of mRNA target selectivity between the two complexes unresolved","How AREX engages export receptors not yet shown"]},{"year":2011,"claim":"Extended DDX39A function to telomere homeostasis through direct TRF2 binding and telomerase association.","evidence":"Co-IP with FXLXP motif domain mapping, shRNA knockdown, telomere length and DNA-damage foci assays","pmids":["21388492"],"confidence":"Medium","gaps":["Mechanism by which DDX39A promotes telomere elongation without altering telomerase activity unclear","Single-lab finding"]},{"year":2011,"claim":"Showed DDX39A is directly targeted by the antiviral GTPase MxA and undergoes intrinsic CRM1-independent nucleocytoplasmic shuttling, linking its helicase activity to antiviral interference and defining shuttling determinants.","evidence":"In vitro binding with recombinant proteins, immunofluorescence, and deletion/domain-mapping shuttling assays","pmids":["21859714","21799930"],"confidence":"Medium","gaps":["Functional consequence of MxA binding on DDX39A activity not directly measured","Shuttling regions mapped largely on UAP56 numbering"]},{"year":2018,"claim":"Connected DDX39A to oncogenic alternative splicing and Wnt/β-catenin signaling, broadening its role to cancer-relevant gene-expression programs.","evidence":"Knockdown of AR-V7 in prostate cells and overexpression/epistasis with TCF4/LEF1 in hepatocellular carcinoma","pmids":["28025139","29867138"],"confidence":"Medium","gaps":["Whether effects are direct splicing/export functions or indirect not fully resolved","Direct RNA targets not all defined"]},{"year":2020,"claim":"Resolved the ATP-dependent assembly logic of the AREX complex and demonstrated that DDX39A-dependent export uses the same NXF1 receptor as the UAP56 pathway.","evidence":"Co-IP under ATP-depleted/replete conditions with mRNA export assays","pmids":["31917363"],"confidence":"Medium","gaps":["Structural basis of apo-complex divergence not yet shown","Trigger for in vivo remodeling unclear"]},{"year":2021,"claim":"Identified ECD as a required cofactor for DDX39A-mediated mRNA export, with export depending on the ECD–DDX39A interaction.","evidence":"Co-IP, siRNA knockdown, FISH export assay, and rescue with an interaction-defective ECD mutant","pmids":["33941617"],"confidence":"Medium","gaps":["Mechanistic role of ECD in the helicase cycle undefined","Single-lab finding"]},{"year":2023,"claim":"Established DDX39A as an interferon-independent antiviral effector that relocalizes to the cytoplasm and binds a defined viral RNA structure to restrict alphaviruses.","evidence":"Genetic screen, CRISPR/siLoss-of-function, biochemical RNA-binding, imaging, and viral replication assays mapping the CHIKV 5'CSE","pmids":["37949067"],"confidence":"High","gaps":["How RNA binding mechanistically blocks replication unresolved","Trigger for nuclear-to-cytoplasmic relocation not defined"]},{"year":2024,"claim":"Revealed a non-canonical protein-loading helicase activity in which DDX39A loads PHAX onto U snRNAs for snRNA export, and clarified non-redundant splicing roles relative to DDX39B.","evidence":"In vitro reconstitution of ATP-dependent PHAX-RNA loading, Co-IP, and paralog complementation splicing assays with sequence analysis","pmids":["39011894","38801080"],"confidence":"High","gaps":["Structural basis of PHAX loading not defined","Full target spectrum of DDX39A-specific splicing events unmapped"]},{"year":2024,"claim":"Provided the structural and C-terminal sequence determinants that explain how DDX39A and UAP56 form distinct apo-complexes, grounding their functional divergence.","evidence":"Structural analysis with chimeric and alanine-substitution mutagenesis and Co-IP/export assays","pmids":["38225262","38377942"],"confidence":"High","gaps":["Atomic-resolution structure of full AREX complex not reported","How structural features dictate mRNA selectivity unresolved"]},{"year":2024,"claim":"Defined a genome-maintenance role: DDX39A resolves RNA-DNA hybrids at stalled forks via RAD51 recruitment to control DNA2 access, with loss conferring chemoresistance in BRCA1/2-deficient cells.","evidence":"Co-IP, chromatin fractionation, R-loop and fork-protection assays with BRCA1/2 epistasis, replicated across two independent reports","pmids":["39706186","39706185"],"confidence":"High","gaps":["How DDX39A choice between RNA and DNA-hybrid substrates is regulated unclear","Relationship between export function and fork function not integrated"]},{"year":2024,"claim":"Placed DDX39A under Erk2 phosphorylation control (Y132/Y138) governing differentiation gene activation and TRF1-dependent suppression of alternative lengthening of telomeres.","evidence":"Erk2 substrate Co-IP/MS, knockout ESCs, phosphosite mutagenesis, ChIP, and ALT assays in mouse cells","pmids":["39107495"],"confidence":"Medium","gaps":["Whether human DDX39A is regulated identically not shown","Mechanism by which DDX39A disrupts TRF1 DNA loops undefined"]},{"year":2024,"claim":"Implicated DDX39A intron retention and a short variant in an oncogenic MYC-export feedback loop, connecting its splicing/export biology to cancer gene circuits.","evidence":"RNA-seq/splicing analysis, SNRPD2/HNRNPL knockdown, MYC mRNA export assay, and ChIP/luciferase in human cells","pmids":["39018261"],"confidence":"Medium","gaps":["Direct role of the short variant in selective MYC export mechanistically unresolved","Single-lab finding"]},{"year":2025,"claim":"Linked a DDX39A missense variant to disease by showing p.Lys137Gln disrupts THOC1 binding and TREX integrity with severe nuclear abnormalities in patient cells.","evidence":"Patient fibroblast studies, Co-IP, structural modeling, and nuclear morphology/viability assays","pmids":["40726340"],"confidence":"Medium","gaps":["Genotype-phenotype scope beyond single proband unresolved","Whether export defect alone explains nuclear lamina disruption unclear"]},{"year":2025,"claim":"Demonstrated DDX39A directly binds and stabilizes specific mRNAs (SP1) to drive downstream programs, including a Ku70/NHEJ-mediated radioresistance axis.","evidence":"RIP-qPCR, ChIP-qPCR, luciferase, knockdown/rescue, and xenograft in human cancer models","pmids":["41984289"],"confidence":"Medium","gaps":["Generality of mRNA-stabilization activity beyond SP1 unclear","Single-lab finding"]},{"year":2026,"claim":"Showed DDX39A stabilizes WISP1 pre-mRNA to activate AKT signaling and immunosuppressive macrophage polarization, and is a druggable target inhibited by fluphenazine.","evidence":"RNA-seq, RIP-seq, knockdown/overexpression, in vivo tumor models, and drug-binding assay in glioblastoma","pmids":["41772197"],"confidence":"Medium","gaps":["Specificity of fluphenazine for DDX39A not fully established","Mechanistic distinction between splicing and stabilization roles unclear"]},{"year":null,"claim":"How DDX39A's many activities — selective mRNA/snRNA export, splicing, fork R-loop resolution, telomere regulation, and antiviral RNA binding — are coordinated and how its complex choice and substrate selectivity are regulated in vivo remains unresolved.","evidence":"","pmids":[],"confidence":"Medium","gaps":["No unifying model integrating nuclear export and genome-maintenance roles","Determinants of mRNA target selectivity between AREX and TREX undefined","No high-resolution structure of the full AREX complex"]}],"mechanism_profile":{"molecular_activity":[{"term_id":"GO:0140657","term_label":"ATP-dependent activity","supporting_discovery_ids":[1,13]},{"term_id":"GO:0003723","term_label":"RNA binding","supporting_discovery_ids":[1,12,21]},{"term_id":"GO:0140098","term_label":"catalytic activity, acting on RNA","supporting_discovery_ids":[1,16]},{"term_id":"GO:0016787","term_label":"hydrolase activity","supporting_discovery_ids":[1]},{"term_id":"GO:0060090","term_label":"molecular adaptor activity","supporting_discovery_ids":[13]}],"localization":[{"term_id":"GO:0005634","term_label":"nucleus","supporting_discovery_ids":[1,3,12]},{"term_id":"GO:0005829","term_label":"cytosol","supporting_discovery_ids":[12]},{"term_id":"GO:0000228","term_label":"nuclear chromosome","supporting_discovery_ids":[16]}],"pathway":[{"term_id":"R-HSA-8953854","term_label":"Metabolism of RNA","supporting_discovery_ids":[4,10,13,14]},{"term_id":"R-HSA-74160","term_label":"Gene expression (Transcription)","supporting_discovery_ids":[4,14]},{"term_id":"R-HSA-9609507","term_label":"Protein localization","supporting_discovery_ids":[3,10,13]},{"term_id":"R-HSA-73894","term_label":"DNA Repair","supporting_discovery_ids":[16]},{"term_id":"R-HSA-168256","term_label":"Immune System","supporting_discovery_ids":[6,12]}],"complexes":["AREX complex","TREX complex"],"partners":["CIP29","ALYREF","THOC1","TRF2","RAD51","MXA","PHAX","ECD"],"other_free_text":[]}},"prefetch_data":{"uniprot":{"accession":"O00148","full_name":"ATP-dependent RNA helicase DDX39A","aliases":["DEAD box protein 39","Nuclear RNA helicase URH49"],"length_aa":427,"mass_kda":49.1,"function":"Helicase that plays an essential role in mRNA export and is involved in multiple steps in RNA metabolism including alternative splicing (PubMed:33941617, PubMed:38801080). Regulates nuclear mRNA export to the cytoplasm through association with ECD (PubMed:33941617). Also involved in spliceosomal uridine-rich small nuclear RNA (U snRNA) export by stimulating the RNA binding of adapter PHAX (PubMed:39011894). Plays a role in the negative regulation of type I IFN production by increasing the nuclear retention of antiviral transcripts and thus reducing their protein expression (PubMed:32393512). Independently of the interferon pathway, plays an antiviral role against alphaviruses by binding to a 5' conserved sequence element in the viral genomic RNA (PubMed:37949067)","subcellular_location":"Nucleus; Cytoplasm","url":"https://www.uniprot.org/uniprotkb/O00148/entry"},"depmap":{"release":"DepMap","has_data":true,"is_common_essential":false,"resolved_as":"","url":"https://depmap.org/portal/gene/DDX39A","classification":"Not 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DDX39B","url":"https://www.omim.org/entry/142560"}],"hpa":{"profiled":true,"resolved_as":"","reliability":"Approved","locations":[{"location":"Nuclear speckles","reliability":"Approved"}],"tissue_specificity":"Tissue enhanced","tissue_distribution":"Detected in all","driving_tissues":[{"tissue":"testis","ntpm":155.6}],"url":"https://www.proteinatlas.org/search/DDX39A"},"hgnc":{"alias_symbol":["DDXL","BAT1L","URH49"],"prev_symbol":["DDX39"]},"alphafold":{"accession":"O00148","domains":[{"cath_id":"3.40.50.300","chopping":"45-248","consensus_level":"high","plddt":94.4067,"start":45,"end":248},{"cath_id":"3.40.50.300","chopping":"260-415","consensus_level":"high","plddt":90.0117,"start":260,"end":415}],"viewer_url":"https://alphafold.ebi.ac.uk/entry/O00148","model_url":"https://alphafold.ebi.ac.uk/files/AF-O00148-F1-model_v6.cif","pae_url":"https://alphafold.ebi.ac.uk/files/AF-O00148-F1-predicted_aligned_error_v6.png","plddt_mean":85.25},"mouse_models":{"mgi_url":"https://www.informatics.jax.org/marker/summary?nomen=DDX39A","jax_strain_url":"https://www.jax.org/strain/search?query=DDX39A"},"sequence":{"accession":"O00148","fasta_url":"https://rest.uniprot.org/uniprotkb/O00148.fasta","uniprot_url":"https://www.uniprot.org/uniprotkb/O00148/entry","alphafold_viewer_url":"https://alphafold.ebi.ac.uk/entry/O00148"}},"corpus_meta":[{"pmid":"20573985","id":"PMC_20573985","title":"The 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DDX39A also undergoes heavy ubiquitylation and its stability is regulated via the ubiquitin-proteasome pathway.\",\n      \"method\": \"Co-immunoprecipitation, mass spectrometry, in vivo binding assay, ubiquitylation assay\",\n      \"journal\": \"Experimental cell research\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — reciprocal Co-IP and MS in single lab, functional RNA unwinding assay included\",\n      \"pmids\": [\"17196963\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2007,\n      \"finding\": \"Recombinant DDX39A (DDX39-L isoform) binds RNA, hydrolyzes NTPs in an RNA-dependent manner, and unwinds double-stranded RNA bidirectionally, establishing it as a bona fide RNA helicase. DDX39A localizes to distinct punctate nuclear foci consistent with a role in RNA splicing/export.\",\n      \"method\": \"In vitro RNA binding assay, NTPase assay, RNA unwinding (helicase) assay, fluorescence microscopy\",\n      \"journal\": \"Cancer biology & therapy\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 / Moderate — direct in vitro biochemical reconstitution of helicase activity with multiple orthogonal assays in a single study\",\n      \"pmids\": [\"17548965\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2004,\n      \"finding\": \"DDX39A (URH49) interacts with the mRNA export factor Aly and can rescue loss of Sub2p (the yeast homolog of UAP56) in Saccharomyces cerevisiae, demonstrating functional conservation in mRNA splicing and nuclear export.\",\n      \"method\": \"Yeast complementation assay, interaction assay with Aly\",\n      \"journal\": \"Nucleic acids research\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — yeast genetic complementation plus protein interaction assay, single lab\",\n      \"pmids\": [\"15047853\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2006,\n      \"finding\": \"siRNA-mediated knockdown of DDX39A (URH49) alone in HeLa cells causes nuclear accumulation of poly(A)+ RNA in a speckled pattern, indicating a role in mRNA nuclear export. Simultaneous knockdown of DDX39A and UAP56 results in major reduction of reporter gene expression, loss of cytoplasmic poly(A)+ RNA, and cell death, demonstrating largely overlapping but essential functions.\",\n      \"method\": \"RNA interference (siRNA), fluorescence in situ hybridization (FISH) for poly(A)+ RNA localization\",\n      \"journal\": \"Gene\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — clean siRNA KD with direct RNA localization readout, single lab, two paralogs compared\",\n      \"pmids\": [\"16949217\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2010,\n      \"finding\": \"DDX39A (URH49) forms a distinct complex termed the AREX (alternative mRNA export) complex with CIP29, whereas its paralog UAP56 forms the canonical human TREX complex. These two complexes regulate distinct subsets of mRNAs genome-wide. Depletion of URH49 causes chromosome arm resolution defects and cytokinesis failure, linked to its specific target mRNAs encoding mitotic regulators.\",\n      \"method\": \"Co-immunoprecipitation, genome-wide mRNA expression analysis, siRNA knockdown with mitotic phenotyping\",\n      \"journal\": \"Molecular biology of the cell\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — reciprocal Co-IP establishing distinct complex, genome-wide target analysis, and defined cellular phenotypes upon KD; multiple orthogonal methods\",\n      \"pmids\": [\"20573985\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2011,\n      \"finding\": \"DDX39A directly interacts with TRF2 via a FXLXP motif in DDX39A binding to the TREX homology domain of TRF2. DDX39A also associates with catalytically competent telomerase through hTERT interaction but does not affect telomerase activity. Overexpression of DDX39A leads to progressive telomere elongation, while shRNA-mediated depletion causes telomere shortening and DNA-damage response foci at both internal genome sites and telomeres (telomere dysfunction-induced foci).\",\n      \"method\": \"Co-immunoprecipitation, domain mapping (FXLXP motif mutagenesis), shRNA knockdown, telomere length analysis, immunofluorescence for DNA damage foci\",\n      \"journal\": \"Aging cell\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — direct binding established by Co-IP with domain mapping, functional consequences from KD and overexpression, single lab\",\n      \"pmids\": [\"21388492\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2011,\n      \"finding\": \"The antiviral GTPase MxA directly binds DDX39A (URH49) in vitro using purified recombinant proteins, forming a complex in the perinuclear region of infected cells. Mouse Mx1 also binds URH49/UAP56 in distinct nuclear dots, suggesting Mx proteins exert antiviral activity by interfering with the RNA helicase functions of URH49 and UAP56.\",\n      \"method\": \"Immunoprecipitation, in vitro binding assay with purified recombinant proteins, immunofluorescence/subcellular localization\",\n      \"journal\": \"The Journal of biological chemistry\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 1–2 / Moderate — in vitro direct binding with recombinant proteins plus cellular co-IP and localization; single lab\",\n      \"pmids\": [\"21859714\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2011,\n      \"finding\": \"DDX39A (URH49) exhibits intrinsic CRM1-independent nucleocytoplasmic shuttling activity. Mapping studies identified distinct regions for intranuclear localization (aa 81–381 of UAP56) and the C-terminus (aa 195–428) as responsible for nucleocytoplasmic shuttling, which is independent of Rae1 interaction.\",\n      \"method\": \"Shuttling assay, deletion/domain mapping, co-immunoprecipitation\",\n      \"journal\": \"PloS one\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — domain mapping with shuttling assays and functional validation, single lab\",\n      \"pmids\": [\"21799930\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2016,\n      \"finding\": \"Simultaneous knockdown of DDX39A and its paralog DDX39B drastically and selectively downregulates AR-V7 splice variant mRNA expression in AR-V7-positive prostate cancer cell lines, indicating that DDX39A (together with DDX39B) regulates alternative splicing to generate the AR-V7 mRNA.\",\n      \"method\": \"shRNA library screen, siRNA knockdown, RT-PCR/qPCR for AR-V7 mRNA\",\n      \"journal\": \"Biochemical and biophysical research communications\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — functional screen confirmed by targeted KD in multiple cell lines, single lab\",\n      \"pmids\": [\"28025139\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2018,\n      \"finding\": \"DDX39A overexpression increases nuclear β-catenin levels and upregulates Wnt/β-catenin pathway target genes in hepatocellular carcinoma cells; knockdown of TCF4 and LEF1 (Wnt/β-catenin co-activators) in DDX39A-overexpressing cells reverses this effect and reduces invasion, placing DDX39A upstream of the Wnt/β-catenin pathway.\",\n      \"method\": \"Overexpression and siRNA knockdown, Western blot for β-catenin nuclear localization, reporter assay, epistasis by co-knockdown\",\n      \"journal\": \"Cell death & disease\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — genetic epistasis via double KD, nuclear fractionation for β-catenin, single lab\",\n      \"pmids\": [\"29867138\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2020,\n      \"finding\": \"In the ATP-depleted state, DDX39A (URH49) forms an apo-AREX complex containing CIP29 but lacking ALYREF and the THO subcomplex, distinct from UAP56's apo-TREX complex. Upon ATP addition, the apo-AREX complex is remodeled into an ATP-TREX-like complex containing THO subcomplex, ALYREF, and CIP29. URH49-dependent mRNA export is achieved through NXF1, the same export receptor as the UAP56 pathway.\",\n      \"method\": \"Co-immunoprecipitation under ATP-depleted and ATP-replete conditions, siRNA knockdown, mRNA export assay\",\n      \"journal\": \"Biochimica et biophysica acta. Gene regulatory mechanisms\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — biochemical dissection of complex assembly states with functional validation, single lab\",\n      \"pmids\": [\"31917363\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2021,\n      \"finding\": \"The mammalian ecdysoneless protein (ECD) physically interacts with DDX39A and is required for mRNA nuclear export; ECD knockdown blocks mRNA export from nucleus to cytoplasm, and this block is rescued by full-length ECD but not by an ECD mutant defective in DDX39A interaction.\",\n      \"method\": \"Co-immunoprecipitation, siRNA knockdown, mRNA export assay (FISH for poly(A)+ RNA), rescue with ECD mutant\",\n      \"journal\": \"Molecular and cellular biology\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — reciprocal Co-IP and functional rescue experiment with interaction-defective mutant, single lab\",\n      \"pmids\": [\"33941617\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2023,\n      \"finding\": \"DDX39A is an antiviral protein against chikungunya virus (CHIKV) and other alphaviruses. Upon infection, predominantly nuclear DDX39A relocates to the cytoplasm, where it inhibits alphavirus replication independently of the canonical interferon pathway. DDX39A biochemically binds CHIKV genomic RNA at the 5' conserved sequence element (5'CSE), and this RNA structure is essential for DDX39A's antiviral activity.\",\n      \"method\": \"Genetic screen, loss-of-function (siRNA/CRISPR), RNA-binding assay (biochemical), subcellular localization (imaging), viral replication assay, structural element mapping\",\n      \"journal\": \"Molecular cell\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1–2 / Strong — genetic screen validated by KO/KD, direct RNA-binding biochemistry, structural element requirement established, IFN-independent mechanism confirmed; multiple orthogonal methods\",\n      \"pmids\": [\"37949067\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2024,\n      \"finding\": \"DDX39A (URH49) stimulates loading of PHAX onto U snRNA in an ATP-dependent manner, thereby facilitating nuclear export of spliceosomal U snRNAs. ALYREF acts as a bridge between PHAX and UAP56/DDX39B in this reaction, revealing a protein-loading helicase activity distinct from classical RNA unwinding.\",\n      \"method\": \"In vitro reconstitution assay for ATP-dependent PHAX-RNA loading, co-immunoprecipitation, nuclear export assay\",\n      \"journal\": \"Nucleic acids research\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 / Moderate — in vitro reconstitution of ATP-dependent protein loading onto RNA; novel activity established biochemically\",\n      \"pmids\": [\"39011894\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2024,\n      \"finding\": \"DDX39A and DDX39B have significant but not fully redundant roles in alternative pre-mRNA splicing. DDX39A cannot complement DDX39B-specific targets such as IL7R exon 6 splicing. Cassette exons specifically dependent on DDX39B (but not DDX39A) have U-poor/C-rich polypyrimidine tracts in the upstream intron, which is a sequence determinant of DDX39B dependency.\",\n      \"method\": \"siRNA knockdown of individual and combined paralogs, RT-PCR splicing assays, sequence analysis of polypyrimidine tracts\",\n      \"journal\": \"Nucleic acids research\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — functional complementation/non-complementation experiments with specific splicing readouts, sequence feature analysis; single lab\",\n      \"pmids\": [\"38801080\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2024,\n      \"finding\": \"DDX39A (URH49) and UAP56 have unique structural features that determine their distinct apo-complex formation. Chimeric mutant analysis identified specific structural regions in each helicase responsible for forming the respective TREX or AREX apo-complexes, providing a molecular basis for functional divergence from their common ancestral gene Sub2.\",\n      \"method\": \"Structural comparison (crystal/structural analysis), chimeric mutant construction and functional analysis, co-immunoprecipitation\",\n      \"journal\": \"Nature communications\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1–2 / Moderate — structural analysis combined with chimeric mutagenesis and functional complex formation assays; multiple orthogonal methods in single study\",\n      \"pmids\": [\"38225262\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2024,\n      \"finding\": \"Upon replication stress, DDX39A acts as an RNA-DNA hybrid (R-loop) resolver at stalled replication forks by unwinding fork-associated RNA-DNA hybrids (RF-RDs). DDX39A is recruited to stalled forks via association with RAD51. This unwinding facilitates regulated DNA2 nuclease access and controlled fork restart; loss of DDX39A causes excessive fork protection and confers chemoresistance in BRCA1/2-deficient cells.\",\n      \"method\": \"Co-immunoprecipitation (RAD51 association), chromatin fractionation, R-loop resolution assay, fork protection assay, siRNA knockdown with defined phenotypic readouts, genetic epistasis with BRCA1/2 deficiency\",\n      \"journal\": \"Molecular cell\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1–2 / Strong — two independent papers (PMIDs 39706186 and 39706185) report the same mechanism with biochemical and genetic methods; replicated finding\",\n      \"pmids\": [\"39706186\", \"39706185\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2024,\n      \"finding\": \"SNRPD2 (an Sm protein) modulates DDX39A intron retention together with HNRNPL to sustain expression of a DDX39A short variant (39A_S). This short variant mediates MYC mRNA nuclear export to maintain high MYC protein levels, and MYC in turn potentiates SNRPD2 transcription, forming a positive feedback loop.\",\n      \"method\": \"RNA-seq/splicing analysis, knockdown of SNRPD2/HNRNPL, mRNA export assay for MYC mRNA, ChIP/luciferase for MYC→SNRPD2 transcription, rescue experiments\",\n      \"journal\": \"Advanced science\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — multiple functional assays establishing pathway, single lab\",\n      \"pmids\": [\"39018261\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2024,\n      \"finding\": \"Erk2 phosphorylates Ddx39 on Y132 and Y138. Phosphorylation of Ddx39 by Erk2 promotes recruitment of Hat1 to acetylate H3K27 and activate differentiation genes in mouse ESCs. Ddx39 is recruited to telomeres by Trf1, where it disrupts Trf1-mediated DNA loops and suppresses alternative lengthening of telomeres (ALT); Erk2 phosphorylation of Ddx39 weakens its interaction with Trf1, releasing it from telomeres and allowing enhanced ALT activity.\",\n      \"method\": \"Co-immunoprecipitation/mass spectrometry (Erk2 substrates), Ddx39 knockout ESCs, phosphorylation site mutagenesis (Y132/Y138), ChIP for Hat1 recruitment, telomere length analysis, ALT assay\",\n      \"journal\": \"Cell death and differentiation\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — kinase substrate relationship and downstream effects established by mutagenesis and KO, single lab\",\n      \"pmids\": [\"39107495\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2024,\n      \"finding\": \"The C-terminal region of DDX39A (URH49) is indispensable for AREX complex formation, and a specific amino acid at the C-terminus of UAP56 (but not URH49) is critical for TREX complex formation; alanine substitution at this residue impairs complex formation and mRNA processing/export activity.\",\n      \"method\": \"Truncation and alanine substitution mutagenesis, co-immunoprecipitation, mRNA export assay\",\n      \"journal\": \"Biochemical and biophysical research communications\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — mutagenesis with functional complex and export readouts, single lab\",\n      \"pmids\": [\"38377942\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2025,\n      \"finding\": \"A missense variant in DDX39A (p.Lys137Gln) causes aberrant nuclear clumping of the mutant protein and prevents its interaction with the TREX component THOC1, thereby impairing TREX complex integrity. Structural modeling shows Lys137 mediates critical inter- and intra-molecular interactions. Cells from the affected proband show severe nuclear morphological abnormalities, disrupted nuclear lamina organization, and increased cell death.\",\n      \"method\": \"Patient-derived fibroblast functional studies, co-immunoprecipitation (DDX39A-K137Q vs THOC1), structural modeling, immunofluorescence for nuclear morphology, cell viability assay\",\n      \"journal\": \"Clinical genetics\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — functional studies in patient cells with Co-IP and structural modeling, single study\",\n      \"pmids\": [\"40726340\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2025,\n      \"finding\": \"DDX39A directly binds SP1 mRNA, stabilizing it and enhancing its translation efficiency without affecting SP1 transcription, as demonstrated by RIP-qPCR. Increased SP1 protein then binds the −223/−214 bp region of the Ku70 promoter (ChIP-qPCR, dual-luciferase assay), activating Ku70 expression and contributing to radioresistance via the non-homologous end-joining pathway.\",\n      \"method\": \"RIP-qPCR, ChIP-qPCR, dual-luciferase reporter assay, siRNA knockdown, rescue experiments, in vivo xenograft\",\n      \"journal\": \"Cellular oncology\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — RNA binding confirmed by RIP-qPCR, promoter binding by ChIP, functional rescue; single lab\",\n      \"pmids\": [\"41984289\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2026,\n      \"finding\": \"DDX39A stabilizes WISP1 pre-mRNA through alternative splicing regulation (identified by RNA-seq and RIP-seq), thereby activating AKT signaling. Secreted WISP1 acts as a paracrine signal promoting immunosuppressive tumor-associated macrophage polarization. The compound fluphenazine hydrochloride binds to and inhibits DDX39A, suppressing glioblastoma growth and macrophage immunosuppression.\",\n      \"method\": \"RNA-seq, RIP-seq, siRNA knockdown and overexpression, in vitro and in vivo tumor models, drug-binding assay\",\n      \"journal\": \"Oncogene\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — RIP-seq for direct RNA binding, pathway validated in vitro and in vivo, single lab\",\n      \"pmids\": [\"41772197\"],\n      \"is_preprint\": false\n    }\n  ],\n  \"current_model\": \"DDX39A (also known as URH49, DDX39, DDXL) is a DEAD-box RNA helicase with ATP-dependent RNA unwinding activity that forms a distinct mRNA export complex (AREX) with CIP29, separate from the UAP56-containing TREX complex, to mediate nuclear export of a specific subset of mRNAs via NXF1; it additionally loads PHAX onto U snRNAs to facilitate snRNA export, regulates alternative pre-mRNA splicing, resolves RNA-DNA hybrids at stalled replication forks in a RAD51-dependent manner to control DNA2-mediated fork processing, interacts with TRF2 and telomerase to modulate telomere length, is phosphorylated by Erk2 (Y132/Y138) to control ESC differentiation and ALT activity, binds specific viral RNA structures (CHIKV 5'CSE) to restrict alphavirus infection in an IFN-independent manner, and is directly targeted by the antiviral GTPase MxA, while a pathogenic K137Q variant disrupts its interaction with THOC1 and impairs TREX complex integrity causing a neurodegenerative phenotype.\"\n}\n```","stage2_raw":"{\n  \"mechanistic_narrative\": \"DDX39A is an ATP-dependent DEAD-box RNA helicase that binds RNA, hydrolyzes NTPs in an RNA-dependent manner, and bidirectionally unwinds double-stranded RNA, functioning principally in nuclear mRNA and snRNA export [#1, #3]. It is the paralog of UAP56/DDX39B and assembles a distinct export complex, the AREX complex, with CIP29 — separate from the canonical UAP56-based TREX complex — and the two complexes regulate distinct genome-wide subsets of mRNAs; depletion of DDX39A causes chromosome arm resolution defects and cytokinesis failure linked to its mitotic-regulator target mRNAs [#0, #4]. Complex identity is determined by ATP state and by unique structural features of each helicase, particularly the C-terminus of DDX39A, with the apo-AREX complex remodeling into a TREX-like complex containing THO, ALYREF, and CIP29 upon ATP addition; export ultimately proceeds through the NXF1 receptor [#10, #15, #19]. Beyond bulk mRNA export, DDX39A performs a protein-loading reaction, stimulating ATP-dependent loading of PHAX onto spliceosomal U snRNAs to drive their nuclear export, and contributes non-redundantly with DDX39B to alternative pre-mRNA splicing [#13, #14]. DDX39A also acts on genome maintenance: upon replication stress it is recruited to stalled forks via RAD51 to resolve fork-associated RNA-DNA hybrids and license regulated DNA2 nuclease access and fork restart, with loss causing excessive fork protection and chemoresistance in BRCA1/2-deficient cells [#16]. It modulates telomere length through direct interaction with TRF2 and association with telomerase, and Erk2 phosphorylation at Y132/Y138 controls its telomeric and differentiation functions [#5, #18]. In antiviral defense, DDX39A relocates from nucleus to cytoplasm upon infection and restricts alphaviruses by binding the CHIKV 5' conserved sequence element in an interferon-independent manner, and is itself targeted by the antiviral GTPase MxA [#6, #12]. A pathogenic p.Lys137Gln variant causes nuclear clumping of the protein and abolishes its interaction with THOC1, impairing TREX integrity and producing severe nuclear morphological abnormalities and increased cell death in patient cells [#20].\",\n  \"teleology\": [\n    {\n      \"year\": 2004,\n      \"claim\": \"Established that DDX39A is a functional ortholog of the yeast mRNA export helicase Sub2/UAP56, defining its baseline role in mRNA splicing and nuclear export.\",\n      \"evidence\": \"Yeast complementation of Sub2p loss and Aly interaction assay\",\n      \"pmids\": [\"15047853\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Did not establish whether DDX39A functions independently of UAP56 in human cells\", \"No biochemical demonstration of helicase activity\"]\n    },\n    {\n      \"year\": 2006,\n      \"claim\": \"Identified CIP29 as a principal DDX39A partner that stimulates its unwinding activity and showed DDX39A interacts with ALY, beginning the definition of its export-complex composition.\",\n      \"evidence\": \"Co-IP/mass spectrometry, in vivo binding, RNA unwinding stimulation, and ubiquitylation assays in human cells\",\n      \"pmids\": [\"17196963\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Did not yet distinguish DDX39A complexes from UAP56/TREX\", \"Functional consequence of ubiquitylation on activity unresolved\"]\n    },\n    {\n      \"year\": 2006,\n      \"claim\": \"Showed by RNA localization that DDX39A is required for mRNA nuclear export and that it shares essential, partly overlapping function with UAP56.\",\n      \"evidence\": \"siRNA knockdown with poly(A)+ RNA FISH in HeLa cells\",\n      \"pmids\": [\"16949217\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Did not identify which specific mRNAs depend on DDX39A versus UAP56\", \"Mechanism of selectivity unaddressed\"]\n    },\n    {\n      \"year\": 2007,\n      \"claim\": \"Confirmed DDX39A is a bona fide ATP-dependent RNA helicase, providing the biochemical foundation for all downstream activities.\",\n      \"evidence\": \"In vitro RNA binding, NTPase, and bidirectional unwinding assays with recombinant protein plus nuclear foci imaging\",\n      \"pmids\": [\"17548965\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"In vitro substrate specificity relative to cellular targets not defined\", \"Link between enzymatic activity and export not directly tested\"]\n    },\n    {\n      \"year\": 2010,\n      \"claim\": \"Defined DDX39A as the core of a distinct AREX complex with CIP29, separate from UAP56's TREX, regulating distinct mRNA subsets and a specific mitotic function.\",\n      \"evidence\": \"Reciprocal Co-IP, genome-wide expression analysis, and siRNA knockdown with mitotic phenotyping\",\n      \"pmids\": [\"20573985\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Determinants of mRNA target selectivity between the two complexes unresolved\", \"How AREX engages export receptors not yet shown\"]\n    },\n    {\n      \"year\": 2011,\n      \"claim\": \"Extended DDX39A function to telomere homeostasis through direct TRF2 binding and telomerase association.\",\n      \"evidence\": \"Co-IP with FXLXP motif domain mapping, shRNA knockdown, telomere length and DNA-damage foci assays\",\n      \"pmids\": [\"21388492\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Mechanism by which DDX39A promotes telomere elongation without altering telomerase activity unclear\", \"Single-lab finding\"]\n    },\n    {\n      \"year\": 2011,\n      \"claim\": \"Showed DDX39A is directly targeted by the antiviral GTPase MxA and undergoes intrinsic CRM1-independent nucleocytoplasmic shuttling, linking its helicase activity to antiviral interference and defining shuttling determinants.\",\n      \"evidence\": \"In vitro binding with recombinant proteins, immunofluorescence, and deletion/domain-mapping shuttling assays\",\n      \"pmids\": [\"21859714\", \"21799930\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Functional consequence of MxA binding on DDX39A activity not directly measured\", \"Shuttling regions mapped largely on UAP56 numbering\"]\n    },\n    {\n      \"year\": 2018,\n      \"claim\": \"Connected DDX39A to oncogenic alternative splicing and Wnt/β-catenin signaling, broadening its role to cancer-relevant gene-expression programs.\",\n      \"evidence\": \"Knockdown of AR-V7 in prostate cells and overexpression/epistasis with TCF4/LEF1 in hepatocellular carcinoma\",\n      \"pmids\": [\"28025139\", \"29867138\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Whether effects are direct splicing/export functions or indirect not fully resolved\", \"Direct RNA targets not all defined\"]\n    },\n    {\n      \"year\": 2020,\n      \"claim\": \"Resolved the ATP-dependent assembly logic of the AREX complex and demonstrated that DDX39A-dependent export uses the same NXF1 receptor as the UAP56 pathway.\",\n      \"evidence\": \"Co-IP under ATP-depleted/replete conditions with mRNA export assays\",\n      \"pmids\": [\"31917363\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Structural basis of apo-complex divergence not yet shown\", \"Trigger for in vivo remodeling unclear\"]\n    },\n    {\n      \"year\": 2021,\n      \"claim\": \"Identified ECD as a required cofactor for DDX39A-mediated mRNA export, with export depending on the ECD–DDX39A interaction.\",\n      \"evidence\": \"Co-IP, siRNA knockdown, FISH export assay, and rescue with an interaction-defective ECD mutant\",\n      \"pmids\": [\"33941617\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Mechanistic role of ECD in the helicase cycle undefined\", \"Single-lab finding\"]\n    },\n    {\n      \"year\": 2023,\n      \"claim\": \"Established DDX39A as an interferon-independent antiviral effector that relocalizes to the cytoplasm and binds a defined viral RNA structure to restrict alphaviruses.\",\n      \"evidence\": \"Genetic screen, CRISPR/siLoss-of-function, biochemical RNA-binding, imaging, and viral replication assays mapping the CHIKV 5'CSE\",\n      \"pmids\": [\"37949067\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"How RNA binding mechanistically blocks replication unresolved\", \"Trigger for nuclear-to-cytoplasmic relocation not defined\"]\n    },\n    {\n      \"year\": 2024,\n      \"claim\": \"Revealed a non-canonical protein-loading helicase activity in which DDX39A loads PHAX onto U snRNAs for snRNA export, and clarified non-redundant splicing roles relative to DDX39B.\",\n      \"evidence\": \"In vitro reconstitution of ATP-dependent PHAX-RNA loading, Co-IP, and paralog complementation splicing assays with sequence analysis\",\n      \"pmids\": [\"39011894\", \"38801080\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Structural basis of PHAX loading not defined\", \"Full target spectrum of DDX39A-specific splicing events unmapped\"]\n    },\n    {\n      \"year\": 2024,\n      \"claim\": \"Provided the structural and C-terminal sequence determinants that explain how DDX39A and UAP56 form distinct apo-complexes, grounding their functional divergence.\",\n      \"evidence\": \"Structural analysis with chimeric and alanine-substitution mutagenesis and Co-IP/export assays\",\n      \"pmids\": [\"38225262\", \"38377942\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Atomic-resolution structure of full AREX complex not reported\", \"How structural features dictate mRNA selectivity unresolved\"]\n    },\n    {\n      \"year\": 2024,\n      \"claim\": \"Defined a genome-maintenance role: DDX39A resolves RNA-DNA hybrids at stalled forks via RAD51 recruitment to control DNA2 access, with loss conferring chemoresistance in BRCA1/2-deficient cells.\",\n      \"evidence\": \"Co-IP, chromatin fractionation, R-loop and fork-protection assays with BRCA1/2 epistasis, replicated across two independent reports\",\n      \"pmids\": [\"39706186\", \"39706185\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"How DDX39A choice between RNA and DNA-hybrid substrates is regulated unclear\", \"Relationship between export function and fork function not integrated\"]\n    },\n    {\n      \"year\": 2024,\n      \"claim\": \"Placed DDX39A under Erk2 phosphorylation control (Y132/Y138) governing differentiation gene activation and TRF1-dependent suppression of alternative lengthening of telomeres.\",\n      \"evidence\": \"Erk2 substrate Co-IP/MS, knockout ESCs, phosphosite mutagenesis, ChIP, and ALT assays in mouse cells\",\n      \"pmids\": [\"39107495\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Whether human DDX39A is regulated identically not shown\", \"Mechanism by which DDX39A disrupts TRF1 DNA loops undefined\"]\n    },\n    {\n      \"year\": 2024,\n      \"claim\": \"Implicated DDX39A intron retention and a short variant in an oncogenic MYC-export feedback loop, connecting its splicing/export biology to cancer gene circuits.\",\n      \"evidence\": \"RNA-seq/splicing analysis, SNRPD2/HNRNPL knockdown, MYC mRNA export assay, and ChIP/luciferase in human cells\",\n      \"pmids\": [\"39018261\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Direct role of the short variant in selective MYC export mechanistically unresolved\", \"Single-lab finding\"]\n    },\n    {\n      \"year\": 2025,\n      \"claim\": \"Linked a DDX39A missense variant to disease by showing p.Lys137Gln disrupts THOC1 binding and TREX integrity with severe nuclear abnormalities in patient cells.\",\n      \"evidence\": \"Patient fibroblast studies, Co-IP, structural modeling, and nuclear morphology/viability assays\",\n      \"pmids\": [\"40726340\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Genotype-phenotype scope beyond single proband unresolved\", \"Whether export defect alone explains nuclear lamina disruption unclear\"]\n    },\n    {\n      \"year\": 2025,\n      \"claim\": \"Demonstrated DDX39A directly binds and stabilizes specific mRNAs (SP1) to drive downstream programs, including a Ku70/NHEJ-mediated radioresistance axis.\",\n      \"evidence\": \"RIP-qPCR, ChIP-qPCR, luciferase, knockdown/rescue, and xenograft in human cancer models\",\n      \"pmids\": [\"41984289\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Generality of mRNA-stabilization activity beyond SP1 unclear\", \"Single-lab finding\"]\n    },\n    {\n      \"year\": 2026,\n      \"claim\": \"Showed DDX39A stabilizes WISP1 pre-mRNA to activate AKT signaling and immunosuppressive macrophage polarization, and is a druggable target inhibited by fluphenazine.\",\n      \"evidence\": \"RNA-seq, RIP-seq, knockdown/overexpression, in vivo tumor models, and drug-binding assay in glioblastoma\",\n      \"pmids\": [\"41772197\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Specificity of fluphenazine for DDX39A not fully established\", \"Mechanistic distinction between splicing and stabilization roles unclear\"]\n    },\n    {\n      \"year\": null,\n      \"claim\": \"How DDX39A's many activities — selective mRNA/snRNA export, splicing, fork R-loop resolution, telomere regulation, and antiviral RNA binding — are coordinated and how its complex choice and substrate selectivity are regulated in vivo remains unresolved.\",\n      \"evidence\": \"\",\n      \"pmids\": [],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"No unifying model integrating nuclear export and genome-maintenance roles\", \"Determinants of mRNA target selectivity between AREX and TREX undefined\", \"No high-resolution structure of the full AREX complex\"]\n    }\n  ],\n  \"mechanism_profile\": {\n    \"molecular_activity\": [\n      {\"term_id\": \"GO:0140657\", \"supporting_discovery_ids\": [1, 13]},\n      {\"term_id\": \"GO:0003723\", \"supporting_discovery_ids\": [1, 12, 21]},\n      {\"term_id\": \"GO:0140098\", \"supporting_discovery_ids\": [1, 16]},\n      {\"term_id\": \"GO:0016787\", \"supporting_discovery_ids\": [1]},\n      {\"term_id\": \"GO:0060090\", \"supporting_discovery_ids\": [13]}\n    ],\n    \"localization\": [\n      {\"term_id\": \"GO:0005634\", \"supporting_discovery_ids\": [1, 3, 12]},\n      {\"term_id\": \"GO:0005829\", \"supporting_discovery_ids\": [12]},\n      {\"term_id\": \"GO:0000228\", \"supporting_discovery_ids\": [16]}\n    ],\n    \"pathway\": [\n      {\"term_id\": \"R-HSA-8953854\", \"supporting_discovery_ids\": [4, 10, 13, 14]},\n      {\"term_id\": \"R-HSA-74160\", \"supporting_discovery_ids\": [4, 14]},\n      {\"term_id\": \"R-HSA-9609507\", \"supporting_discovery_ids\": [3, 10, 13]},\n      {\"term_id\": \"R-HSA-73894\", \"supporting_discovery_ids\": [16]},\n      {\"term_id\": \"R-HSA-168256\", \"supporting_discovery_ids\": [6, 12]}\n    ],\n    \"complexes\": [\"AREX complex\", \"TREX complex\"],\n    \"partners\": [\"CIP29\", \"ALYREF\", \"THOC1\", \"TRF2\", \"RAD51\", \"MxA\", \"PHAX\", \"ECD\"],\n    \"other_free_text\": []\n  }\n}","audit_flag":null,"evaluation":{"pairwise":"win","faith_supported":8,"faith_total":8,"faith_pct":100.0}}