Affinage

CRLF3

Cytokine receptor-like factor 3 · UniProt Q8IUI8

Length
442 aa
Mass
49.8 kDa
Annotated
2026-06-09
13 papers in source corpus 11 papers cited in narrative 11 extracted findings
Cross-family judge vs UniProt: Affinage preferred faithfulness: 7/7 claims corpus-supported (100%)

Mechanistic narrative

Synthesis pass · prose summary of the discoveries below

CRLF3 is an evolutionarily conserved cytokine receptor that mediates neuroprotection and regulates neuronal maturation and hematopoietic development (PMID:28769759, PMID:37168680, PMID:35051265). In insect and human neurons it is required for the anti-apoptotic effect of erythropoietin (Epo) and its non-erythropoietic splice variant EV-3 against serum-deprivation-, hypoxia-, and rotenone-induced cell death, with receptor loss abolishing protection (PMID:28769759, PMID:31680856, PMID:37168680). Its ligand spectrum is broader than the classical Epo receptor, encompassing thrombopoietin and the erythropoietic/neuroprotective peptides HBSP, P16, and EMP1 but not prolactin or growth hormone, and downstream signaling proceeds through JAK/STAT activity (PMID:40903881). Neuroprotection is executed at least in part by preventing hypoxia-induced upregulation of pro-apoptotic acetylcholinesterase, with the protective response showing a biphasic dependence on ligand dose (PMID:36329181). Beyond cytokine signaling, CRLF3 controls neuronal differentiation and maturation downstream of RhoA signaling, and a non-expression-impairing L389P variant compromises dendrite outgrowth, branching, and synaptic function in human organoids and mouse hippocampal neurons (PMID:34233200, PMID:37712888). CRLF3 is also required for early hematopoiesis in zebrafish and regulates the preplatelet-to-platelet fission step in mice, where it interacts with Hippo pathway members and constrains microtubule glutamylation and stability (PMID:35795682, PMID:35051265). A physical interaction with ACTR2 has been linked to hepatocellular carcinoma cell behavior (PMID:40469577).

Mechanistic history

Synthesis pass · year-by-year structured walk · 11 steps
  1. 2017 Medium

    Established that CRLF3 is functionally required for erythropoietin-mediated neuroprotection, defining the protein as a participant in Epo anti-apoptotic signaling rather than a passive marker.

    Evidence RNAi knockdown in primary Tribolium castaneum brain neurons with recombinant human Epo and EV-3 in apoptosis assays

    PMID:28769759

    Open questions at the time
    • Did not demonstrate direct ligand binding to CRLF3
    • Downstream signaling pathway not defined
    • Mammalian relevance untested in this study
  2. 2019 Medium

    Confirmed the neuroprotective requirement for CRLF3 in a second, hemimetabolous insect species, indicating evolutionary conservation of the Epo-CRLF3 axis.

    Evidence Soaking RNAi in primary Locusta migratoria brain neuron cultures with hypoxia-induced apoptosis assays and recombinant human Epo

    PMID:31680856

    Open questions at the time
    • No identification of the endogenous insect ligand
    • No biochemical receptor-ligand interaction shown
  3. 2021 Medium

    Connected CRLF3 to an endogenous cytokine context by showing it is required for neuroprotection conferred by native hemolymph, moving beyond exogenous human Epo.

    Evidence RNAi knockdown of crlf3 in locust and Tribolium neurons with hemolymph serum survival assays

    PMID:33897456

    Open questions at the time
    • The endogenous hemolymph ligand was not molecularly identified
    • Direct binding not demonstrated
  4. 2021 Medium

    Extended CRLF3 function into mammalian neurodevelopment, placing it as a regulator of neuronal maturation downstream of RhoA signaling.

    Evidence Loss-of-function in patient-derived hiPSC cerebral organoids with phenotypic rescue and pathway analysis

    PMID:34233200

    Open questions at the time
    • Link between cytokine receptor activity and RhoA signaling unresolved
    • Single lab, organoid model
  5. 2022 Medium

    Identified a non-neuronal physiological role in megakaryocyte biology, showing CRLF3 controls the preplatelet-to-platelet fission step via microtubule regulation and Hippo pathway interaction.

    Evidence Crlf3 knockout mouse, platelet counts, EM, microtubule glutamylation/stability assays, co-IP with Hippo pathway members

    PMID:35051265

    Open questions at the time
    • Direct biochemical partners within the Hippo pathway not fully resolved
    • Mechanism linking CRLF3 to glutamylation enzymes unknown
    • Single lab
  6. 2022 Medium

    Defined a developmental hematopoietic requirement for CRLF3, showing it is needed for primitive and early definitive hematopoiesis across lineages.

    Evidence CRISPR-generated crlf3 mutant zebrafish with in situ hybridization for progenitor markers

    PMID:35795682

    Open questions at the time
    • Signaling pathway driving progenitor reduction not defined
    • Single model system
  7. 2022 Medium

    Resolved a downstream effector of CRLF3 neuroprotection by showing it acts by preventing hypoxia-induced upregulation of pro-apoptotic acetylcholinesterase, with biphasic ligand dose dependence.

    Evidence RNAi of ace-1/ace-2, pharmacological AChE inhibition, and Epo treatment in Tribolium neurons under hypoxia

    PMID:36329181

    Open questions at the time
    • Intermediate signaling between CRLF3 and ace transcription not mapped
    • Conservation of AChE mechanism in mammals untested
  8. 2023 Medium

    Demonstrated that human CRLF3 functions as the receptor for the non-erythropoietic Epo variant EV-3 in neuroprotection, transferring the insect mechanism to human neurons.

    Evidence CRLF3 knockout human iPSC-derived neurons in rotenone apoptosis assays with EV-3 and apoptotic gene expression profiling

    PMID:37168680

    Open questions at the time
    • Direct EV-3 binding to CRLF3 not biochemically shown
    • Receptor activation mechanism unresolved
  9. 2023 Medium

    Showed that a specific CRLF3 missense variant (L389P) selectively disrupts neuronal maturation and synaptic function without affecting protein expression, separating its developmental function from protein stability.

    Evidence L389P knock-in hiPSC organoids and mice, neuronal morphometry, hippocampal electrophysiology, Western blot

    PMID:37712888

    Open questions at the time
    • Molecular consequence of L389P on receptor function undefined
    • Mechanistic link to dendrite/synapse machinery unknown
  10. 2025 Medium

    Defined CRLF3 as a promiscuous cytokine receptor activated by thrombopoietin and multiple erythropoietic/neuroprotective peptides via JAK/STAT signaling, distinguishing it from the classical Epo receptor.

    Evidence Locust neuron apoptosis assays with specific cytokines/peptides, RNAi confirmation, and JAK/STAT readouts

    PMID:40903881

    Open questions at the time
    • Direct binding affinities for the various ligands not measured
    • Structural basis of broad ligand recognition unknown
  11. 2025 Low

    Implicated CRLF3 in cancer through a physical interaction with ACTR2 driving hepatocellular carcinoma proliferation, migration, and immune escape.

    Evidence Co-immunoprecipitation, proliferation/migration assays in HepG2, CD8+ T cell assays, and nude mouse xenografts with ACTR2 rescue

    PMID:40469577

    Open questions at the time
    • Single co-IP without reciprocal/structural validation
    • Mechanism connecting CRLF3-ACTR2 to proliferation undefined
    • Relationship to cytokine receptor function unclear

Open questions

Synthesis pass · forward-looking unresolved questions
  • Direct biochemical demonstration of ligand binding to CRLF3 and the structural/signaling mechanism converting receptor engagement into the divergent RhoA, Hippo/microtubule, and JAK/STAT outputs remains unresolved.
  • No direct receptor-ligand binding assay reported
  • No structural model of the receptor
  • How one receptor drives neuroprotection, dendritogenesis, hematopoiesis, and platelet fission is unexplained

Mechanism profile

Synthesis pass · controlled-vocabulary classification · explore literature graph →
Molecular activity
GO:0060089 molecular transducer activity 3 GO:0048018 receptor ligand activity 1
Pathway
R-HSA-5357801 Programmed Cell Death 3 R-HSA-162582 Signal Transduction 2 R-HSA-109582 Hemostasis 1
Partners
ACTR2

Evidence

Reading pass · 11 per-paper findings extracted from the source corpus
Year Finding Method Journal Conf PMIDs
2021 CRLF3 loss-of-function in patient-derived hiPSC-forebrain cerebral organoids causes neuronal differentiation, survival, and maturation defects through impaired RhoA signaling, identifying CRLF3 as a regulator of neuronal maturation downstream of RhoA. hiPSC-derived cerebral organoids from NF1-TGD patients with reduced CRLF3 expression; phenotypic rescue experiments; pathway analysis Cell reports Medium 34233200
2017 Insect (Tribolium castaneum) ortholog of CRLF3 is required for erythropoietin (Epo)-mediated neuroprotection: RNAi knockdown of CRLF3 abolished the ability of recombinant human Epo and non-erythropoietic splice variant EV-3 to prevent serum-deprivation- and hypoxia-induced apoptosis in primary neuronal cultures. In vitro RNAi knockdown in primary Tribolium brain neuron cultures; apoptosis assay with recombinant human Epo and EV-3 treatment Frontiers in molecular neuroscience Medium 28769759
2019 CRLF3 ortholog in Locusta migratoria mediates erythropoietin-induced neuroprotection: soaking RNAi knockdown of Lm-crlf3 abolished the protective effect of recombinant human Epo against hypoxia-induced apoptosis in primary locust brain neuron cultures. Soaking RNAi in primary Locusta migratoria brain cell cultures; hypoxia-induced apoptosis assay with recombinant human Epo Frontiers in molecular neuroscience Medium 31680856
2021 CRLF3 mediates neuroprotection by an endogenous conserved cytokine present in locust hemolymph: RNAi knockdown of crlf3 in both Locusta migratoria and Tribolium castaneum neurons abolished the neuroprotective effect of locust hemolymph serum against hypoxia-induced apoptosis. RNAi knockdown of crlf3 in primary locust and Tribolium neuron/hemocyte cultures; cell survival assay with locust hemolymph serum supplementation Frontiers in physiology Medium 33897456
2022 CRLF3 deficiency in mice leads to a 25–48% reduction in platelet count without affecting other blood cell lineages, and Crlf3−/− preplatelets show increased microtubule stability associated with increased microtubule glutamylation via CRLF3 interaction with key members of the Hippo pathway, identifying CRLF3 as a regulator of the preplatelet-to-platelet maturation (fission) step. Crlf3 knockout mouse model; platelet counting; electron microscopy of preplatelets; microtubule stability assays; co-immunoprecipitation with Hippo pathway members; JAK2 V617F essential thrombocythemia mouse model cross Blood Medium 35051265
2022 CRLF3 is required for early hematopoiesis in zebrafish: crlf3 mutants generated by genome editing show significant reduction in primitive hematopoiesis and early definitive hematopoiesis, affecting multiple lineages via decreased early progenitors. CRISPR/genome editing to generate crlf3 mutant zebrafish; in situ hybridization and cell lineage markers for hematopoietic progenitors Frontiers in immunology Medium 35795682
2023 Human CRLF3 functions as a receptor for the non-erythropoietic Epo splice variant EV-3 mediating neuroprotection: CRLF3 knockout iPSC-derived neurons failed to be protected by EV-3 against rotenone-induced apoptosis, and this was associated with differential expression of pro- and anti-apoptotic genes. CRLF3 knockout iPSC lines differentiated to neurons; rotenone-induced apoptosis assay with EV-3 treatment; apoptotic gene expression profiling Frontiers in molecular neuroscience Medium 37168680
2023 The CRLF3 L389P variant does not impair protein expression but causes impaired neuronal maturation and dendrite formation in human cerebral organoids and mouse brains; Crlf3L389P-mutant mouse hippocampal neurons have reduced dendrite lengths, branching, firing rates, and synaptic current amplitudes without axonal deficits. hiPSC lines and genetically engineered mice carrying L389P knock-in; cerebral organoid modeling; neuronal morphometry; electrophysiology of hippocampal neurons; Western blot for protein expression Human molecular genetics Medium 37712888
2022 CRLF3-mediated neuroprotection in insects operates through prevention of hypoxia-induced upregulation of pro-apoptotic acetylcholinesterase (ace-1 and ace-2): activation of CRLF3 by erythropoietin prevented increased acetylcholinesterase expression under apoptogenic conditions, while high (toxic) Epo concentrations induced ace-1 expression and promoted apoptosis. RNAi knockdown of ace-1 and ace-2 in Tribolium primary brain neurons; pharmacological AChE inhibition; Epo treatment; cell survival and gene expression assays under hypoxia Scientific reports Medium 36329181
2025 Locust CRLF3 can be activated by human thrombopoietin (neuroprotective), but not by human prolactin or growth hormone; additionally, erythropoietic/neuroprotective peptides HBSP, P16, and EMP1 also protect locust neurons via CRLF3, indicating a broader ligand spectrum than the classical Epo receptor. Downstream signaling involves JAK/STAT activity. Primary locust brain neuron cultures; hypoxia-induced apoptosis assays with specific cytokines and peptides; RNAi knockdown of CRLF3 to confirm receptor dependence; JAK/STAT pathway readouts Journal of neurochemistry Medium 40903881
2025 CRLF3 physically interacts with ACTR2 (co-immunoprecipitation confirmed), and this interaction promotes hepatocellular carcinoma cell proliferation, migration, and immune escape; knockdown of CRLF3 inhibited HCC cell growth and tumor growth in vivo, and increased CD8+ T cell activity, effects that were rescued by ACTR2 overexpression. Co-immunoprecipitation and Western blot; MTT, colony formation, Transwell assays in HepG2 cells; flow cytometry for apoptosis and CD8+ T cell activation; nude mouse xenograft model Cytotechnology Low 40469577

Source papers

Stage 0 corpus · 13 papers · ranked by NIH iCite citations
Year Title Journal Citations PMID
2021 Patient-derived iPSC-cerebral organoid modeling of the 17q11.2 microdeletion syndrome establishes CRLF3 as a critical regulator of neurogenesis. Cell reports 42 34233200
2017 The Insect Ortholog of the Human Orphan Cytokine Receptor CRLF3 Is a Neuroprotective Erythropoietin Receptor. Frontiers in molecular neuroscience 26 28769759
2019 The Orphan Cytokine Receptor CRLF3 Emerged With the Origin of the Nervous System and Is a Neuroprotective Erythropoietin Receptor in Locusts. Frontiers in molecular neuroscience 21 31680856
2022 CRLF3 plays a key role in the final stage of platelet genesis and is a potential therapeutic target for thrombocythemia. Blood 19 35051265
2021 A Genome-wide Association Study Identifies SERPINB10, CRLF3, STX7, LAMP3, IFNG-AS1, and KRT80 As Risk Loci Contributing to Cutaneous Leishmaniasis in Brazil. Clinical infectious diseases : an official publication of the Infectious Diseases Society of America 19 32830257
2023 The cytokine receptor CRLF3 is a human neuroprotective EV-3 (Epo) receptor. Frontiers in molecular neuroscience 8 37168680
2021 Locust Hemolymph Conveys Erythropoietin-Like Cytoprotection via Activation of the Cytokine Receptor CRLF3. Frontiers in physiology 8 33897456
2022 Cytokine Receptor-Like Factor 3 (CRLF3) Contributes to Early Zebrafish Hematopoiesis. Frontiers in immunology 7 35795682
2023 A common single nucleotide variant in the cytokine receptor-like factor-3 (CRLF3) gene causes neuronal deficits in human and mouse cells. Human molecular genetics 6 37712888
2022 Protection of insect neurons by erythropoietin/CRLF3-mediated regulation of pro-apoptotic acetylcholinesterase. Scientific reports 4 36329181
2025 Cytokine Receptor-like Factor 3 (CRLF3) and Its Emerging Roles in Neurobiology, Hematopoiesis and Related Human Diseases. International journal of molecular sciences 3 40331935
2025 Multiple Mammalian Cytokines and Erythropoietin-Mimetic Peptides Protect Insect Neurons via Phylogenetically Conserved Cytokine Receptor-Like Factor 3 (CRLF3). Journal of neurochemistry 1 40903881
2025 Mechanisms of CRLF3-targeted binding to ACTR2 to promote hepatocellular carcinoma progression and effects on the immune microenvironment. Cytotechnology 0 40469577

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