Affinage

RIOK1

Serine/threonine-protein kinase RIO1 · UniProt Q9BRS2

Length
568 aa
Mass
65.6 kDa
Annotated
2026-06-10
23 papers in source corpus 14 papers cited in narrative 14 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

RIOK1 is an atypical kinase/ATPase that operates both as a substrate-recruiting adapter within the PRMT5 methylosome and as an active protein kinase driving oncogenic signaling (PMID:21081503, PMID:35589951). As a stoichiometric component of the PRMT5-WD45/MEP50 core, RIOK1 binds PRMT5 mutually exclusively with pICln through a distinct interface on the PRMT5 TIM-barrel domain (consensus GQF[D/E]DA[E/D]), recruiting RNA-binding substrates such as nucleolin and NF90 for symmetrical arginine dimethylation (PMID:21081503, PMID:33624332, PMID:36040368); consistent with this methylosome role, RIOK1 depletion is selectively lethal in MTAP-deleted cancer cells within the MAT2A/PRMT5/RIOK1 axis, and its kinase activity supports cell survival and ribosome biogenesis (PMID:27068473, PMID:29983885, PMID:37301535). As a kinase, RIOK1 phosphorylates G3BP2 at Thr226 to promote MDM2-mediated p53 degradation and radioresistance, MYH9 at Ser1943 (within a SPC25-scaffolded trimer) to drive nuclear MYH9 accumulation and Wnt/β-catenin activation, and YBX1 at Ser165 to promote its nuclear localization and JAK2/STAT3 activation (PMID:35589951, PMID:39488790, PMID:41354180). RIOK1 also undergoes liquid-liquid phase separation, nucleating stress granules with IGF2BP1 and G3BP1 that sequester PTEN mRNA and suppress its translation (PMID:40467995). RIOK1 protein stability is gated by a methylation–phosphorylation switch: SETD7 methylates K411 (reversed by LSD1) to license FBXO6-mediated ubiquitination, while CK2 phosphorylation of T410 antagonizes K411 methylation and stabilizes the protein (PMID:29384474). Across model systems, RIOK1 acts as a modulator of Ras signaling and innate immune signaling (PMID:24929033, PMID:29719537).

Mechanistic history

Synthesis pass · year-by-year structured walk · 14 steps
  1. 2010 High

    Established RIOK1's first defined molecular role: not as a free kinase but as a dedicated adapter that loads specific RNA-binding substrates onto the PRMT5 arginine methyltransferase complex.

    Evidence Biochemical purification, reciprocal co-IP, stoichiometric complex analysis, and in vitro methylation assay of nucleolin

    PMID:21081503

    Open questions at the time
    • Did not define how RIOK1 selects which substrates to recruit
    • Relationship between adapter function and RIOK1's catalytic activity unresolved
  2. 2014 Medium

    Placed the RIOK1 ortholog genetically within oncogenic Ras/Raf signaling, indicating a conserved role in proliferative signaling beyond the methylosome.

    Evidence RNAi suppressor screen of the multi-vulva phenotype in C. elegans

    PMID:24929033

    Open questions at the time
    • Ortholog genetics do not define the molecular step in the Ras pathway
    • No mammalian biochemical mechanism shown
  3. 2016 Medium

    Connected RIOK1 to a therapeutic vulnerability, showing its depletion is selectively lethal in MTAP-deleted cells downstream of PRMT5 inhibition.

    Evidence shRNA screening with metabolomic profiling and methyltransferase inhibition assays

    PMID:27068473

    Open questions at the time
    • RIOK1's direct mechanistic contribution inferred from complex membership, not enzymatic characterization
    • Did not test whether kinase activity is required
  4. 2017 Medium

    Defined a RAS-mutant-selective requirement for RIOK1 in proliferation and invasion, linking it to NF-κB signaling and pro-invasive effectors.

    Evidence shRNA knockdown, 3D culture, proteomics, NF-κB reporter, and in vivo lung colonization in RAS-mutant cells

    PMID:28499923

    Open questions at the time
    • Direct kinase substrates in this context not identified
    • Mechanism linking RIOK1 to NF-κB unresolved
  5. 2018 High

    Resolved how RIOK1 protein levels are controlled, defining a SETD7/LSD1 methylation–CK2 phosphorylation switch at T410/K411 that gates FBXO6-mediated degradation.

    Evidence In vitro methylation/phosphorylation assays, K411R mutagenesis, ubiquitination assays, and mouse xenografts

    PMID:29384474

    Open questions at the time
    • Upstream signals controlling SETD7/LSD1/CK2 activity on RIOK1 not defined
    • Whether stability switch couples to specific RIOK1 functions unknown
  6. 2018 Medium

    Distinguished RIOK1's kinase requirement from its methylosome role, showing kinase activity is needed for survival regardless of MTAP status.

    Evidence CRISPR analog-sensitive kinase alleles with isogenic cell comparison and chemical-genetic inhibition

    PMID:29983885

    Open questions at the time
    • The MTAP-independent kinase substrates were not identified here
    • Single-lab chemical-genetic system
  7. 2018 Medium

    Identified a conserved negative-feedback role for the RIOK1 ortholog in innate immunity, acting downstream of SKN-1 to suppress p38 MAPK/PMK-1 signaling.

    Evidence RNAi, genetic epistasis, qRT-PCR, and infection assays in C. elegans

    PMID:29719537

    Open questions at the time
    • Molecular mechanism of p38 suppression not defined
    • Mammalian relevance of immune role untested
  8. 2021 High

    Provided structural resolution of the RIOK1–PRMT5 interaction, mapping a consensus motif binding a novel PRMT5 site distinct from pICln.

    Evidence Peptide truncation/mutation studies and protein crystallography of the RioK1 peptide-PRMT5 complex

    PMID:33624332

    Open questions at the time
    • Structure of full-length RIOK1 within the complex not determined
    • How the interface switches with pICln dynamically unresolved
  9. 2022 Medium

    Established RIOK1 as a direct kinase against G3BP2 at Thr226, linking its catalytic activity to p53 suppression and radioresistance.

    Evidence Co-IP, in vitro kinase assay with phosphosite mapping, ubiquitination assays, and in vitro/in vivo functional tests in colorectal cancer

    PMID:35589951

    Open questions at the time
    • Mechanism linking G3BP2-T226 to MDM2 activity not fully resolved
    • Single-lab substrate identification
  10. 2022 Medium

    Expanded the RIOK1-adapter substrate repertoire by identifying NF90 as a PRMT5 substrate recruited via the RioK1 complex.

    Evidence Co-IP, in vitro/in vivo methylation assay, and PRMT5 inhibitor treatment

    PMID:36040368

    Open questions at the time
    • Functional consequence of NF90 methylation not defined
    • Recruitment determinants not mapped
  11. 2023 Medium

    Positioned RIOK1 as a c-myc/E2F transcriptional target with a ribosome biogenesis function in prostate cancer.

    Evidence Transcription factor target analysis, dominant-negative D324A mutant, rRNA quantification, and toyocamycin inhibition

    PMID:37301535

    Open questions at the time
    • Direct biochemical role of RIOK1 in rRNA processing not defined
    • rRNA changes could be indirect via toyocamycin
  12. 2024 High

    Defined a SPC25-scaffolded RIOK1–MYH9 trimer in which RIOK1 phosphorylates MYH9-S1943 to drive nuclear MYH9 and Wnt/β-catenin-mediated stemness and platinum resistance.

    Evidence Co-IP, in vitro kinase assay with phosphosite mutagenesis, nuclear fractionation, inhibitory peptide, and patient-derived organoids

    PMID:39488790

    Open questions at the time
    • How SPC25 scaffolding selects MYH9 for phosphorylation not detailed
    • Link between cytoskeletal disengagement and CTNNB1 transcription mechanistically incomplete
  13. 2025 Medium

    Revealed a non-catalytic biophysical function: RIOK1 undergoes phase separation to build PTEN-mRNA-sequestering stress granules that reprogram metabolism and confer TKI resistance.

    Evidence Phase separation assays, stress granule immunofluorescence, RNA-IP, translation and metabolic profiling, and in vivo TKI resistance models in HCC

    PMID:40467995

    Open questions at the time
    • The RIOK1 domain/region driving phase separation not characterized
    • Selectivity for PTEN mRNA mechanism unresolved
  14. 2025 Medium

    Added YBX1-S165 as a RIOK1 kinase substrate, coupling its catalytic activity to YBX1 nuclear localization and JAK2/STAT3-driven lenvatinib resistance.

    Evidence Co-IP, phosphosite identification, nuclear fractionation, functional rescue, and mouse xenograft

    PMID:41354180

    Open questions at the time
    • How S165 phosphorylation drives YBX1 nuclear import not defined
    • Single-lab substrate identification

Open questions

Synthesis pass · forward-looking unresolved questions
  • It remains unresolved how RIOK1's distinct activities — methylosome adapter, ATPase/kinase toward diverse substrates, ribosome biogenesis factor, and phase-separation scaffold — are coordinated or selected within a single cell.
  • No unified structural/biochemical model linking the functions
  • Substrate selectivity determinants for the kinase activity undefined
  • Conditions favoring phase separation versus complex assembly unknown

Mechanism profile

Synthesis pass · controlled-vocabulary classification · explore literature graph →
Molecular activity
GO:0060090 molecular adaptor activity 3 GO:0140096 catalytic activity, acting on a protein 3 GO:0003723 RNA binding 1 GO:0140657 ATP-dependent activity 1
Localization
GO:0005634 nucleus 2 GO:0031410 cytoplasmic vesicle 1
Pathway
R-HSA-162582 Signal Transduction 2 R-HSA-8953854 Metabolism of RNA 2 R-HSA-392499 Metabolism of proteins 1
Complex memberships
PRMT5-WD45/MEP50 methylosomeRIOK1-SPC25-MYH9 trimerRIOK1-positive stress granules

Evidence

Reading pass · 14 per-paper findings extracted from the source corpus
Year Finding Method Journal Conf PMIDs
2010 RioK1 is a stoichiometric component of the PRMT5 complex, binding PRMT5 in a mutually exclusive fashion with pICln. RioK1 and pICln both bind to a PRMT5-WD45/MEP50 core, forming distinct complexes. RioK1 acts as an adapter protein that recruits the RNA-binding protein nucleolin to the PRMT5 complex for its symmetrical arginine dimethylation. Biochemical purification, co-immunoprecipitation, stoichiometric complex analysis, in vitro methylation assay The Journal of biological chemistry High 21081503
2016 RIOK1 is a co-complex protein of PRMT5 and its depletion creates a vulnerability in MTAP-deleted cancer cells, placing RIOK1 functionally downstream of MTA accumulation-mediated PRMT5 inhibition in the MAT2A/PRMT5/RIOK1 axis. shRNA screening, metabolomic profiling, biochemical methyltransferase inhibition assays Cell reports Medium 27068473
2018 RIOK1 is methylated at K411 by SETD7 methyltransferase; LSD1 reverses this methylation. The K411-methylated form is recognized by FBXO6 (via its FBA domain), leading to RIOK1 ubiquitination and degradation. CK2 phosphorylates RIOK1 at T410, which stabilizes RIOK1 by antagonizing K411 methylation and blocking FBXO6 recruitment. This methylation-phosphorylation switch regulates RIOK1 protein stability and tumor growth/metastasis. In vitro methylation/phosphorylation assays, mutagenesis (K411R), co-immunoprecipitation, ubiquitination assays, mouse xenograft models eLife High 29384474
2018 RIOK1 kinase activity is required for cancer cell survival irrespective of MTAP status. Using CRISPR/Cas9-generated analog-sensitive alleles, differential kinase activity requirement was NOT detected between MTAP-proficient and MTAP-deleted cells, contrasting with the differential PRMT5 dependency. CRISPR/Cas9 analog-sensitive kinase allele engineering, isogenic cell line comparison, chemical-genetic inhibition Oncotarget Medium 29983885
2017 RIOK1 knockdown in RAS-mutant cancer cells impairs proliferation and invasiveness, activates NF-κB signaling, and reduces expression of pro-invasive proteins Metadherin and Stathmin1. RIOK1 promotes cell cycle progression. These effects are specific to RAS-mutant cells and not observed in RAS-wildtype cells. shRNA knockdown, 3D culture, proteomics, NF-κB reporter assays, in vivo lung colonization assay EBioMedicine Medium 28499923
2021 The binding interface between RioK1 and the PRMT5 TIM barrel domain was mapped by peptide truncation and mutation studies. A consensus amino acid sequence GQF[D/E]DA[E/D] is involved in binding. Protein crystallography revealed that the RioK1-derived peptide interacts with a novel protein-protein interaction site on PRMT5, distinct from the pICln binding site. Peptide truncation and mutation studies, protein crystallography Chembiochem : a European journal of chemical biology High 33624332
2022 RIOK1 phosphorylates G3BP2 at Thr226, increasing G3BP2 activity. RIOK1-mediated G3BP2 phosphorylation facilitates MDM2-mediated ubiquitination of p53, suppressing the p53 signaling pathway and contributing to radioresistance in colorectal cancer. RIOK1 and G3BP2 physically interact. Co-immunoprecipitation, in vitro kinase assay (phosphorylation at Thr226), ubiquitination assay, knockdown/inhibitor experiments in vitro and in vivo Oncogene Medium 35589951
2022 NF90 (Nuclear Factor 90) specifically interacts with the PRMT5-WD45-RioK1 complex and is symmetrically dimethylated by PRMT5 within the RG-rich region of its C-terminus, establishing NF90 as a new substrate recruited via the RioK1 adaptor. Co-immunoprecipitation, in vitro/in vivo methylation assay, PRMT5 inhibitor treatment Biological chemistry Medium 36040368
2018 In C. elegans, riok-1 acts upstream of the p38 MAPK/pmk-1 pathway as a negative regulator (suppressor) of innate immune signaling. Genetic epistasis placed riok-1 downstream of skn-1 (a p38 MAPK transcription factor), suggesting a negative feedback loop: SKN-1 → RIOK-1 ⊣ p38 MAPK/PMK-1. RNAi knockdown, genetic epistasis analysis, quantitative RT-PCR, infection resistance assays Frontiers in immunology Medium 29719537
2014 In C. elegans, depletion of riok-1 (ortholog of mammalian RIOK1) suppresses the multi-vulva phenotype caused by oncogenic Ras/Raf signaling, placing riok-1 as a modulator of the Ras signaling pathway. RNAi screen in C. elegans, multi-vulva phenotype assay, promoter-GFP expression analysis Gene expression patterns : GEP Medium 24929033
2024 RIOK1 forms a trimeric complex with SPC25 and MYH9, where SPC25 acts as a scaffold. Within this complex, RIOK1 phosphorylates MYH9 at Ser1943. This phosphorylation causes MYH9 to disengage from the cytoskeleton and accumulate in the nucleus, potentiating CTNNB1 transcription and Wnt/β-catenin signaling activation, promoting cancer stem cell phenotypes and platinum resistance. Co-immunoprecipitation, in vitro kinase assay (phosphorylation at Ser1943), mutagenesis, nuclear fractionation, competitive inhibitory peptide (CBP1), patient-derived organoids Advanced science (Weinheim, Baden-Wurttemberg, Germany) High 39488790
2025 RIOK1 undergoes liquid-liquid phase separation and incorporates IGF2BP1 and G3BP1 into stress granules. These RIOK1-positive stress granules sequester PTEN mRNA, reducing its translation, thereby activating the pentose phosphate pathway and facilitating stress resolution and cytoprotection against tyrosine kinase inhibitors in hepatocellular carcinoma. Phase separation assays, stress granule immunofluorescence, mRNA translation assays, RNA immunoprecipitation, metabolic profiling, in vitro and in vivo TKI resistance models Nature cancer Medium 40467995
2025 RIOK1 interacts with YBX1 and induces phosphorylation of YBX1 at Ser165, promoting nuclear localization of YBX1, which in turn activates the JAK2/STAT3 pathway and increases lenvatinib resistance in hepatocellular carcinoma cells. Co-immunoprecipitation, phosphorylation site identification, nuclear fractionation, knockdown/overexpression functional assays, mouse xenograft Biochimica et biophysica acta. Molecular cell research Medium 41354180
2023 RIOK1 is identified as a downstream target gene of the c-myc/E2F transcription factors in prostate cancer. A dominant-negative RIOK1-D324A mutant reduces PCa cell proliferation, and toyocamycin treatment (RIOK1 biochemical inhibitor) causes rapid decreases in RIOK1 protein, total rRNA content, and shifts the 28S/18S rRNA ratio, consistent with a role in ribosome biogenesis. Chromatin immunoprecipitation/transcription factor target analysis, dominant-negative mutagenesis (D324A), rRNA quantification, pharmacological inhibition with toyocamycin The American journal of pathology Medium 37301535

Source papers

Stage 0 corpus · 23 papers · ranked by NIH iCite citations
Year Title Journal Citations PMID
2016 MTAP Deletions in Cancer Create Vulnerability to Targeting of the MAT2A/PRMT5/RIOK1 Axis. Cell reports 364 27068473
2010 RioK1, a new interactor of protein arginine methyltransferase 5 (PRMT5), competes with pICln for binding and modulates PRMT5 complex composition and substrate specificity. The Journal of biological chemistry 131 21081503
2018 Targeting posttranslational modifications of RIOK1 inhibits the progression of colorectal and gastric cancers. eLife 63 29384474
2017 The Atypical Kinase RIOK1 Promotes Tumor Growth and Invasive Behavior. EBioMedicine 43 28499923
2022 RIOK1 mediates p53 degradation and radioresistance in colorectal cancer through phosphorylation of G3BP2. Oncogene 33 35589951
2025 RIOK1 phase separation restricts PTEN translation via stress granules activating tumor growth in hepatocellular carcinoma. Nature cancer 23 40467995
2021 Biochemical Investigation of the Interaction of pICln, RioK1 and COPR5 with the PRMT5-MEP50 Complex. Chembiochem : a European journal of chemical biology 22 33624332
2020 Elevated Expression of RIOK1 Is Correlated with Breast Cancer Hormone Receptor Status and Promotes Cancer Progression. Cancer research and treatment 15 32599985
2018 RIOK-1 Is a Suppressor of the p38 MAPK Innate Immune Pathway in Caenorhabditis elegans. Frontiers in immunology 14 29719537
2024 Targeting the SPC25/RIOK1/MYH9 Axis to Overcome Tumor Stemness and Platinum Resistance in Epithelial Ovarian Cancer. Advanced science (Weinheim, Baden-Wurttemberg, Germany) 12 39488790
2022 RIOK1 is associated with non-small cell lung cancer clinical characters and contributes to cancer progression. Journal of Cancer 12 35281872
2018 RIOK1 kinase activity is required for cell survival irrespective of MTAP status. Oncotarget 12 29983885
2014 Expression pattern and first functional characterization of riok-1 in Caenorhabditis elegans. Gene expression patterns : GEP 11 24929033
2023 The Oncogenic Protein Kinase/ATPase RIOK1 Is Up-Regulated via the c-myc/E2F Transcription Factor Axis in Prostate Cancer. The American journal of pathology 10 37301535
2023 The RioK1 network determines p53 activity at multiple levels. Cell death discovery 7 37935656
2023 Riok1, A Novel Potential Target in MSI-High p53 Mutant Colorectal Cancer Cells. Molecules (Basel, Switzerland) 6 37298928
2025 Phospho-Regulatory Network of the Right Open Reading Frame Kinase 1 (RIOK1), Its Functional Relevance, and Cancer Treatment Prospects. Omics : a journal of integrative biology 4 40982243
2021 First Evidence of Function for Schistosoma japonicumriok-1 and RIOK-1. Pathogens (Basel, Switzerland) 4 34358012
2025 RIOK1: A Novel Oncogenic Driver in Hepatocellular Carcinoma. Cancer medicine 2 39865406
2025 Activation of YBX1 and JAK2/STAT3 pathways by RIOK1 increases lenvatinib resistance in hepatocellular carcinoma cells. Biochimica et biophysica acta. Molecular cell research 1 41354180
2022 NF90/NFAR (nuclear factors associated with dsRNA) - a new methylation substrate of the PRMT5-WD45-RioK1 complex. Biological chemistry 1 36040368
2026 Levosimendan inhibits HIV-1 infection in myeloid cells in the RIOK1-dependent manner. bioRxiv : the preprint server for biology 0 41993256
2026 U2SURP increases CREB3L2 RNA stability and RIOK1 transcription to enhance lenvatinib resistance in hepatocellular carcinoma cells. Pathology, research and practice 0 41997041

Missed literature

Know a paper Affinage missed for RIOK1? Flag it for the maintainers and the community.

No submissions yet.