Affinage

RIOK2

Serine/threonine-protein kinase RIO2 · UniProt Q9BVS4

Length
552 aa
Mass
63.3 kDa
Annotated
2026-04-28
18 papers in source corpus 14 papers cited in narrative 14 extracted findings

Mechanistic narrative

Synthesis pass · prose summary of the discoveries below

RIOK2 is a multifunctional atypical kinase/ATPase that integrates ribosome biogenesis, transcriptional regulation, and innate immune signaling. Its ATPase activity is essential for cytoplasmic maturation and release from pre-40S ribosomal subunits, a process stimulated by RSK-mediated phosphorylation downstream of Ras/MAPK signaling, and loss of this catalytic activity in leukemic cells causes ribosomal instability, decreased protein synthesis, and apoptosis (PMID:34125833, PMID:34359076). Independent of its ribosome assembly role, RIOK2 functions as a transcription factor through a winged helix-turn-helix DNA-binding domain and two transactivation domains, directly regulating hematopoietic transcription factors (GATA1, GATA2, SPI1, RUNX3, KLF1) to drive erythroid differentiation, and transcriptionally controlling TRiC chaperonin and dyskerin complex subunits required for telomerase activity and telomere maintenance (PMID:34937919, PMID:39164231). RIOK2 also interacts with FADD to drive lysosome-to-ER transport via myosin II activation, directly cleaving caspase-8 and GSDMD to execute pyroptosis during host defense against Yersinia infection (PMID:41249793).

Mechanistic history

Synthesis pass · year-by-year structured walk · 10 steps
  1. 2018 Medium

    Establishing that RIOK2 expression is post-transcriptionally regulated by miRNAs answered how RIOK2 levels are controlled in cancer cells and linked its abundance to tumor-promoting phenotypes.

    Evidence Dual luciferase reporter assay validating miR-145 targeting of RIOK2 3′-UTR in NSCLC cells

    PMID:29749434

    Open questions at the time
    • Single lab; miR-145–RIOK2 axis not validated in non-cancer primary cells
    • Downstream effectors of RIOK2 mediating the phenotype not identified
  2. 2019 High

    Solving the crystal structure of human RIOK2 with a selective inhibitor revealed the architecture of the ATP-binding pocket and the structural basis for selectivity over RIOK1/RIOK3, enabling rational drug design.

    Evidence X-ray crystallography of RIOK2–inhibitor complex with active-site residue analysis

    PMID:30991936

    Open questions at the time
    • No structure of RIOK2 bound to a physiological substrate or pre-40S particle at this point
    • Conformational dynamics during catalytic cycle unknown
  3. 2020 Medium

    Demonstration that miR-4744 directly regulates RIOK2 and that RIOK2 promotes glioma invasion through EMT markers provided a second miRNA regulatory axis and linked RIOK2 to epithelial–mesenchymal transition.

    Evidence Dual luciferase reporter, RIOK2 overexpression rescue of miR-4744 effects in glioma cells

    PMID:32125767

    Open questions at the time
    • Single lab; EMT pathway activation not confirmed with genetic rescue of individual targets
    • Mechanism connecting RIOK2 to MMP2/MMP9 upregulation not resolved
  4. 2021 High

    Discovery that RSK phosphorylation of RIOK2 stimulates pre-40S maturation, RIOK2 release, and nuclear re-import established how Ras/MAPK signaling directly couples mitogenic signals to ribosome biogenesis.

    Evidence Phosphoproteomics, phospho-site mutagenesis, ribosome maturation assays, and nuclear re-import tracking

    PMID:34125833

    Open questions at the time
    • Precise structural mechanism by which phosphorylation triggers RIOK2 dissociation from the pre-40S particle not resolved
    • Whether other kinases contribute to RIOK2 phosphorylation in different cellular contexts unknown
  5. 2021 High

    Identification of RIOK2 as a bona fide transcription factor with a winged helix-turn-helix DNA-binding domain that directly regulates hematopoietic master regulators revealed a function entirely independent of its ribosome assembly role.

    Evidence Domain mutagenesis of DNA-binding and transactivation domains, reporter assays, and differentiation phenotypes in primary human HSPCs

    PMID:34937919

    Open questions at the time
    • Genome-wide binding profile (ChIP-seq) of RIOK2 at hematopoietic loci not reported
    • How RIOK2 partitions between ribosome assembly and transcription factor functions is unknown
  6. 2022 High

    Showing that RIOK2 ATPase activity is selectively essential for AML cell survival but dispensable in fibroblasts identified RIOK2 as a therapeutic vulnerability in leukemia and validated pharmacological targeting in vivo.

    Evidence CRISPR kinome screen, ATPase-dead mutant rescue, CQ211 inhibitor crystal structure, xenograft model

    PMID:34359076 PMID:35584513

    Open questions at the time
    • Whether RIOK2 essentiality extends beyond AML to other hematological malignancies not tested
    • Contribution of transcription factor function versus ribosome assembly function to AML dependency not deconvolved
  7. 2022 Medium

    Identification of Sp1 as a transcriptional activator of the RIOK2 promoter and observation that RIOK2 loss activates MAPK signaling (ERK/JNK phosphorylation) provided upstream and downstream regulatory context.

    Evidence ChIP and dual-luciferase reporter for Sp1 binding; phospho-western blots in porcine intestinal epithelial cells

    PMID:36361502

    Open questions at the time
    • Sp1 regulation not confirmed in human cells
    • Mechanism by which RIOK2 suppresses MAPK pathway phosphorylation not identified
  8. 2024 High

    Demonstrating that RIOK2 transcriptionally controls TRiC and dyskerin complex subunits to maintain telomerase activity connected RIOK2's transcription factor function to telomere biology and showed rescue of telomere shortening in IPF patient fibroblasts.

    Evidence Domain mutagenesis, telomere length assays, telomerase activity assay, ectopic RIOK2 rescue in IPF fibroblasts

    PMID:39164231

    Open questions at the time
    • Whether RIOK2 directly binds promoters of TRiC/dyskerin genes (ChIP-seq) not shown
    • In vivo relevance of RIOK2–telomere axis in aging or disease models not established
  9. 2024 Medium

    Development of a molecular glue degrader (CQ627) that recruits E3 ligase RNF126 to degrade RIOK2 via the ubiquitin-proteasome system demonstrated targeted protein degradation as an alternative pharmacological strategy.

    Evidence Molecular glue degrader, ubiquitin-proteasome pathway validation, flow cytometry, xenograft model

    PMID:39721086

    Open questions at the time
    • RNF126 recruitment mechanism at the structural level not resolved
    • Selectivity of CQ627 across the proteome not fully profiled
  10. 2025 High

    Discovery that RIOK2 interacts with FADD, drives lysosome-to-ER transport via myosin II, and directly triggers caspase-8/GSDMD cleavage for pyroptosis established RIOK2 as an innate immune effector beyond its ribosome and transcription functions.

    Evidence Co-IP, in vitro caspase-8/GSDMD cleavage reconstitution, organelle fractionation, myosin II activation assay, Yersinia infection model in vivo

    PMID:41249793

    Open questions at the time
    • Whether RIOK2-driven pyroptosis operates in cell types beyond macrophages unknown
    • Structural basis for RIOK2's direct cleavage activation of caspase-8 not determined

Open questions

Synthesis pass · forward-looking unresolved questions
  • How RIOK2 partitions among its ribosome assembly, transcription factor, and innate immune functions — and whether these are regulated by distinct post-translational modifications or protein complexes — remains an open question.
  • No integrated model explaining how RIOK2 switches between ribosome biogenesis, transcriptional regulation, and pyroptosis
  • Genome-wide direct DNA-binding targets of RIOK2 not mapped by ChIP-seq
  • Whether RIOK2 kinase substrates beyond CLK1 exist in human cells is unresolved

Mechanism profile

Synthesis pass · controlled-vocabulary classification · explore literature graph →
Molecular activity
GO:0140657 ATP-dependent activity 5 GO:0140096 catalytic activity, acting on a protein 3 GO:0003677 DNA binding 2 GO:0140110 transcription regulator activity 2
Localization
GO:0005634 nucleus 2 GO:0005829 cytosol 2 GO:0005764 lysosome 1 GO:0005783 endoplasmic reticulum 1
Pathway
R-HSA-392499 Metabolism of proteins 3 R-HSA-5357801 Programmed Cell Death 2 R-HSA-74160 Gene expression (Transcription) 2 R-HSA-1266738 Developmental Biology 1 R-HSA-168256 Immune System 1
Partners
CASP8CLK1FADDGSDMDRIPK1RNF126RPS6
Complex memberships
FADD-RIPK1-caspase-8 complexpre-40S ribosomal subunit

Evidence

Reading pass · 14 per-paper findings extracted from the source corpus
Year Finding Method Journal Conf PMIDs
2019 Crystal structure of human RIOK2 bound to a specific inhibitor was solved, revealing that the inhibitor binds in the ATP-binding site and forms extensive hydrophobic interactions with residues at the entrance to the ATP-binding site, explaining inhibitor specificity over RIOK1 and RIOK3. X-ray crystallography with structural analysis of active site residues Open biology High 30991936
2021 RIOK2 is phosphorylated by the MAPK-activated kinase RSK; this phosphorylation stimulates cytoplasmic maturation of late pre-40S particles, facilitates RIOK2 release from pre-40S particles and its nuclear re-import, and is required for optimal protein synthesis and cell proliferation. Biochemical assays, phosphoproteomics, knockdown/overexpression with ribosome maturation readouts, nuclear re-import tracking PLoS genetics High 34125833
2022 The ATPase/kinase activity of RIOK2 is necessary for cell survival in AML; loss of RIOK2 leads to decreased protein synthesis and ribosomal instability followed by apoptosis in leukemic cells but not fibroblasts; pharmacological inhibition recapitulates these effects in vivo. CRISPR-Cas9 domain-focused kinome screen, ATPase mutant rescue, small-molecule inhibitor, in vivo xenograft model, protein synthesis assay Blood High 34359076
2021 RIOK2 functions as a transcription factor with a winged helix-turn-helix DNA-binding domain and two transactivation domains; it drives erythroid differentiation while suppressing megakaryopoiesis and myelopoiesis by directly regulating key hematopoietic transcription factors GATA1, GATA2, SPI1, RUNX3, and KLF1 in primary human stem and progenitor cells. Loss-of-function in primary human HSPCs, domain mutagenesis, transcriptomic analysis, reporter assays Nature immunology High 34937919
2024 RIOK2 transcriptionally regulates subunits of the TRiC chaperonin and dyskerin complexes; loss of RIOK2 or its DNA-binding/transactivation properties downregulates mRNA expression of these complex subunits, impairing telomerase activity and causing telomere shortening; ectopic RIOK2 expression rescues telomere shortening in IPF patient-derived fibroblasts. Loss-of-function, domain mutagenesis, telomere length assays, telomerase activity assay, ectopic expression rescue Nature communications High 39164231
2022 Crystal structure of RIOK2 bound to the potent inhibitor CQ211 (Kd = 6.1 nM) was determined, providing molecular mechanism of inhibition; CQ211 binding to the ATP site leads to inhibition of RIOK2 enzymatic activity, decreased cancer cell proliferation, and in vivo antitumor efficacy. X-ray crystallography, enzymatic binding assay, cell proliferation assay, mouse xenograft model Journal of medicinal chemistry High 35584513
2025 RIOK2 interacts with FADD and drives the transport of lysosomes to the ER by activating myosin II, translocating the FADD-RIPK1-caspase-8 complex from lysosomes to the ER; RIOK2's ATPase activity enhances its binding to this complex and directly triggers caspase-8 and GSDMD cleavage both at the ER and in vitro, driving pyroptosis and host defense against Yersinia infection. Co-immunoprecipitation, in vitro cleavage assay, organelle fractionation, myosin II activation assay, live-cell imaging, loss-of-function in macrophages, in vivo infection model Nature communications High 41249793
2018 miR-145 directly targets the 3'-UTR of RIOK2 and NOB1 mRNAs (validated by dual luciferase reporter assay), reducing their protein expression and suppressing NSCLC cell viability, migration, and invasion. Dual luciferase reporter assay, western blot, cell viability/migration/invasion assays International journal of oncology Medium 29749434
2020 miR-4744 directly binds to the 3'-UTR of RIOK2 and negatively regulates RIOK2 expression; RIOK2 promotes glioma cell migration and invasion through upregulation of MMP2, MMP9, and EMT markers (N-cadherin, β-catenin, Twist1, fibronectin, ZEB-1); overexpression of RIOK2 reverses the effects of miR-4744 overexpression. Dual luciferase reporter assay, siRNA knockdown, overexpression rescue, wound healing/Transwell assay, western blot Journal of cellular and molecular medicine Medium 32125767
2022 RIOK2 knockdown in oral squamous cell carcinoma cells decreased cell growth, S6 ribosomal protein expression, and protein synthesis, consistent with its role as a key enzyme in pre-40S ribosomal complex maturation. siRNA knockdown, cell growth assay, S6 protein western blot, protein synthesis assay Current oncology (Toronto, Ont.) Medium 36661680
2020 In Strongyloides stercoralis (a parasitic nematode ortholog), Ss-RIOK-2 encodes a catalytically active kinase localized primarily in the cytoplasm of intestinal and hypodermal cells; dominant-negative ATP-binding site mutant (K123A) abrogates egg hatching, rescued by wild-type Ss-RIOK-2 but not by Ss-RIOK-1, demonstrating specific and essential kinase activity for larval development. Mutagenesis (D228A, K123A), transgenic expression, in vivo larval development assay, rescue experiment International journal for parasitology Medium 32592810
2022 RIOK2 knockdown in porcine intestinal epithelial cells promotes activation of the MAPK signaling pathway by increasing phosphorylation of ERK and JNK; additionally, the transcription factor Sp1 binds the RIOK2 promoter region to regulate its expression, as demonstrated by dual-luciferase reporter and ChIP assays. siRNA knockdown, western blot for phospho-ERK/JNK, dual-luciferase reporter assay, ChIP assay International journal of molecular sciences Medium 36361502
2025 RIOK2 phosphorylates CLK1 at Ser341 during thermal stress recovery, enabling CLK1 localization to nuclear stress bodies (nSBs) and thereby promoting CLK1-mediated rephosphorylation of SRSFs and temperature-dependent pre-mRNA splicing regulation. Phospho-mapping, kinase assay, nSB localization imaging, splicing assays bioRxivpreprint Medium bio_10.1101_2025.10.21.683800
2024 The molecular glue degrader CQ627 (based on CQ211 scaffold) recruits E3 ubiquitin ligase RNF126 to induce RIOK2 degradation via the ubiquitin-proteasome system (DC50 = 410 nM in MOLT4 cells), induces apoptosis, and blocks cell cycle in G2/M phase. Molecular glue degrader design, ubiquitin-proteasome pathway validation, flow cytometry, in vivo xenograft model European journal of medicinal chemistry Medium 39721086

Source papers

Stage 0 corpus · 18 papers · ranked by NIH iCite citations
Year Title Journal Citations PMID
2016 High Expression of RIOK2 and NOB1 Predict Human Non-small Cell Lung Cancer Outcomes. Scientific reports 31 27346559
2022 Targeting RIOK2 ATPase activity leads to decreased protein synthesis and cell death in acute myeloid leukemia. Blood 28 34359076
2018 miR‑145 inhibits human non‑small-cell lung cancer growth by dual-targeting RIOK2 and NOB1. International journal of oncology 22 29749434
2020 RIOK2 is negatively regulated by miR-4744 and promotes glioma cell migration/invasion through epithelial-mesenchymal transition. Journal of cellular and molecular medicine 21 32125767
2021 Identification of RIOK2 as a master regulator of human blood cell development. Nature immunology 20 34937919
2019 Crystal structure of human RIOK2 bound to a specific inhibitor. Open biology 15 30991936
2021 RIOK2 phosphorylation by RSK promotes synthesis of the human small ribosomal subunit. PLoS genetics 14 34125833
2022 Discovery of 8-(6-Methoxypyridin-3-yl)-1-(4-(piperazin-1-yl)-3-(trifluoromethyl)phenyl)-1,5-dihydro-4H-[1,2,3]triazolo[4,5-c]quinolin-4-one (CQ211) as a Highly Potent and Selective RIOK2 Inhibitor. Journal of medicinal chemistry 11 35584513
2021 RIOK2 Inhibitor NSC139021 Exerts Anti-Tumor Effects on Glioblastoma via Inducing Skp2-Mediated Cell Cycle Arrest and Apoptosis. Biomedicines 8 34572430
2022 Analysis of RIOK2 Functions in Mediating the Toxic Effects of Deoxynivalenol in Porcine Intestinal Epithelial Cells. International journal of molecular sciences 6 36361502
2022 RIOK2 Contributes to Cell Growth and Protein Synthesis in Human Oral Squamous Cell Carcinoma. Current oncology (Toronto, Ont.) 6 36661680
2024 RIOK2 transcriptionally regulates TRiC and dyskerin complexes to prevent telomere shortening. Nature communications 5 39164231
2020 RIOK-2 protein is essential for egg hatching in a common parasitic nematode. International journal for parasitology 5 32592810
2020 Towards a RIOK2 chemical probe: cellular potency improvement of a selective 2-(acylamino)pyridine series. RSC medicinal chemistry 4 34046605
2024 Discovery of the first examples of right open reading frame kinase 2 (RIOK2) molecular glue degraders. European journal of medicinal chemistry 3 39721086
2023 Exploration of tricyclic heterocycles as core structures for RIOK2 inhibitors. RSC medicinal chemistry 3 37859717
2025 Design, Synthesis and Evaluation of 4-Methoxy-1H-[1,2,3]triazolo[4,5-c]quinolines as Highly Potent and Oral Available RIOK2 Inhibitors. Journal of medicinal chemistry 0 40811658
2025 RIOK2 kinase regulates the translocation of the FADD-RIPK1-Caspase-8 complex to the ER and the cleavage of Gasdermin D to drive pyroptosis. Nature communications 0 41249793