CNTFR

CNTFRα is a GPI-anchored receptor subunit that serves as the ligand-binding specificity component of a tripartite cytokine receptor complex: it first captures CNTF and then nucleates recruitment of gp130 and LIFRβ, whose heterodimerization activates constitutively associated JAKs to drive tyrosine phosphorylation, STAT recruitment and dimerization, and nuclear transcriptional activation (PMID:10812968). Beyond the canonical JAK/STAT output, soluble CNTFRα together with CNTF engages gp130-dependent PI3K and MAPK signaling to promote macrophage chemotaxis (PMID:11162290), and CNTFRα can pre-associate with the LIFR membrane-distal cytokine binding domain in a ligand-free manner (PMID:11943154). CNTFRα also functions as the receptor for CLCF1/CLC, with CLC co-expressed alongside cntfr in developing muscle at the time of motor neuron survival (PMID:15683542); in cancer, the CLCF1–CNTFR axis drives STAT3 activation and TGF-β production, and an engineered soluble decoy (eCNTFR-Fc) sequesters CLCF1 to suppress tumor growth, stemness, and an immunosuppressive microenvironment in lung adenocarcinoma and hepatocellular carcinoma (PMID:31700175, PMID:42102942). CNTFR expression is post-transcriptionally controlled through its 3'-UTR by miR-21-5p, loss of which derepresses CNTFR and constrains esophageal squamous carcinoma cell proliferation and invasion (PMID:41673571).

1. 1993 Medium

   Establishing the chromosomal locus of human CNTFR provided the genomic anchor for studying the receptor gene.

   Evidence PCR-based somatic cell and radiation hybrid mapping localizing CNTFR to 9p13

   PMID:8244400

   Open questions at the time

   • Locus mapping alone gives no functional or regulatory information
2. 2000 High

   Defining the receptor assembly resolved how CNTFRα converts ligand binding into intracellular signaling: it captures CNTF first, then recruits gp130 and LIFRβ to activate JAK/STAT transcriptional output.

   Evidence Biochemical receptor complex assembly and JAK/STAT pathway signaling studies

   PMID:10812968

   Open questions at the time

   • Stoichiometry and structural arrangement of the tripartite complex not resolved here
   • Does not address ligands beyond CNTF
3. 2000 Medium

   Demonstrating GPI anchoring explained how a transmembrane-domain-less receptor subunit can present ligand and shed as a soluble form.

   Evidence Biochemical characterization of receptor membrane topology

   PMID:10812968

   Open questions at the time

   • Mechanism and regulation of shedding to generate soluble CNTFRα not defined
4. 2000 Medium

   Identifying that soluble CNTFRα with CNTF drives macrophage chemotaxis showed signaling extends beyond JAK/STAT to gp130-dependent PI3K and MAPK pathways and to non-neural cell behaviors.

   Evidence Microchemotaxis assays with anti-gp130 neutralization, pharmacological PI3K/MAPK inhibition, and anti-phosphotyrosine Western blot in macrophages

   PMID:11162290

   Open questions at the time

   • ~130 kD phosphoprotein only presumed to be gp130
   • Direct downstream effectors of PI3K/MAPK in this context not mapped
5. 2002 Medium

   Showing that the LIFR CBD1 domain binds soluble CNTFRα without ligand raised the possibility of a pre-formed ligand-free receptor subcomplex.

   Evidence In vitro purified-domain interaction assay plus CBD1 blockade of CNTF (but not IL-6/LIF) signaling in Ntera/D1 cells

   PMID:11943154

   Open questions at the time

   • Single lab, single study
   • Physiological relevance of a ligand-free CNTFRα–LIFR complex not established in vivo
6. 2005 Low

   Co-expression of CLC with cntfr and clf in developing muscle supported CLC/sCNTFR as a physiological ligand for the receptor complex during motor neuron survival.

   Evidence Single-cell in situ hybridization co-expression analysis in mouse embryonic tissues

   PMID:15683542

   Open questions at the time

   • Co-expression only; functional receptor activation by CLC/sCNTFR not reconstituted in this study
   • Causal link to motor neuron loss not directly tested here
7. 2019 High

   Identifying CNTFR as the receptor for CLCF1 in lung adenocarcinoma converted CNTFR into an oncology target addressable by ligand sequestration.

   Evidence Engineered eCNTFR-Fc decoy neutralization in xenograft and autochthonous KRAS/p53-mutant mouse tumor models

   PMID:31700175

   Open questions at the time

   • Downstream signaling consequences of CLCF1 blockade not detailed in this study
   • Basis for KRAS-mutation-dependent efficacy not mechanistically resolved
8. 2024 Medium

   Linking the CLCF1-CNTFR axis to STAT3 and TGF-β output defined the signaling consequences of axis blockade and extended therapeutic relevance to hepatocellular carcinoma and CAR-T engineering.

   Evidence eCNTFR-Fc in vitro/xenograft assays, STAT3 phosphorylation Western blot, TGF-β measurement, and armored GPC3 CAR-T functional assays

   PMID:42102942

   Open questions at the time

   • Single lab study
   • Direct versus indirect contribution of CNTFR to the immunosuppressive microenvironment not fully dissected
9. 2026 Medium

   Demonstrating direct miR-21-5p targeting of the CNTFR 3'-UTR established a post-transcriptional control point linking CNTFR loss to a pro-tumor phenotype in esophageal squamous carcinoma.

   Evidence Luciferase reporter assay with miR-21-5p mimics/inhibitors plus RT-qPCR, Western blot, and proliferation/invasion/migration assays

   PMID:41673571

   Open questions at the time

   • Single lab
   • Whether CNTFR loss acts through the canonical receptor complex in this context not addressed

• How the same CNTFR axis is partitioned between neurotrophic/developmental survival signaling and tumor-promoting versus tumor-suppressive roles across tissues remains unresolved.
• No structural model of the tripartite complex in the timeline
• Mechanism of soluble CNTFRα generation and trans-signaling not defined
• Context-dependence of CNTFR as tumor driver versus suppressor unexplained