{"gene":"SMO","run_date":"2026-06-10T07:46:36","timeline":{"discoveries":[{"year":2005,"finding":"Localization of Smo to primary cilia is required for Hedgehog signal transduction; loss of the retrograde IFT motor (Dnchc2) disrupts Smo ciliary localization and prevents both Gli activator and repressor function, as well as effective proteolytic processing of Gli3.","method":"Mouse genetics (retrograde IFT motor mutants), immunofluorescence localization of Smo to primary cilia, Gli3 processing assay","journal":"Developmental biology","confidence":"High","confidence_rationale":"Tier 2 / Strong — direct localization experiment with functional consequence (Gli activator/repressor loss), replicated across multiple genetic backgrounds in vivo","pmids":["16229832"],"is_preprint":false},{"year":2006,"finding":"Fused (Fu) and Costal2 (Cos2) form a complex that regulates Smo phosphorylation and cell-surface accumulation in Drosophila: Cos2 binds Smo C-terminal domain to block Hh-induced phosphorylation, while Fu phosphorylates Cos2 at Ser572 to attenuate Cos2–Smo interaction and promote Smo surface accumulation.","method":"Drosophila genetics (fu mutant clones, dominant-negative Fu), co-immunoprecipitation, epistasis analysis, phosphorylation mapping","journal":"Genes & development","confidence":"High","confidence_rationale":"Tier 2 / Strong — reciprocal co-IP, genetic epistasis, phosphorylation-site mapping, multiple orthogonal methods in one study","pmids":["17671093"],"is_preprint":false},{"year":2008,"finding":"PP4 phosphatase counteracts kinase-mediated phosphorylation of Smo in Drosophila: RNAi knockdown of PP4 elevates Smo phosphorylation and accumulation, increasing Hh signaling; deletion of a PP4-interaction domain (aa 626–678) in Smo promotes Smo phosphorylation and signaling; Hh downregulates the Smo–PP4 interaction, which is mediated by Cos2.","method":"In vivo RNAi screen in Drosophila, domain-deletion mutagenesis, co-immunoprecipitation, Hh pathway activity assays","journal":"Development (Cambridge, England)","confidence":"High","confidence_rationale":"Tier 2 / Strong — in vivo RNAi screen, domain deletion mutagenesis, Co-IP, multiple orthogonal methods","pmids":["19088085"],"is_preprint":false},{"year":2010,"finding":"GRK2 (Gprk2) promotes high-level Hedgehog signaling in Drosophila by phosphorylating Smo C-tail at Ser741/Thr742, facilitated by prior PKA and CK1 phosphorylation; additionally, Gprk2 dimerizes/oligomerizes and binds Smo C-tail in a kinase-independent manner to stabilize the active Smo conformation, forming a positive feedback loop downstream of PKA and CK1.","method":"Drosophila genetics, phosphorylation-site mutagenesis, co-immunoprecipitation, kinase-dead constructs, epistasis analysis","journal":"Genes & development","confidence":"High","confidence_rationale":"Tier 1–2 / Strong — mutagenesis of phosphorylation sites, kinase-dead constructs, Co-IP, epistasis, multiple orthogonal methods","pmids":["20844016"],"is_preprint":false},{"year":2012,"finding":"The Evc/Evc2 complex co-precipitates with Smo and is required for Hh signaling downstream of Smo ciliary translocation in chondrocytes: Smo translocation to the cilium is normal in Evc2-deficient cells after SAG treatment, but Gli3 recruitment to cilia tips and Sufu/Gli3 dissociation are impaired, and Evc silencing in Sufu−/− cells attenuates Hh output.","method":"Mouse genetic models, co-immunoprecipitation (Smo–Evc/Evc2), immunofluorescence (ciliary localization), Sufu−/− epistasis","journal":"Human molecular genetics","confidence":"High","confidence_rationale":"Tier 2 / Strong — reciprocal Co-IP, direct ciliary localization imaging, genetic epistasis in multiple mutant backgrounds","pmids":["23026747"],"is_preprint":false},{"year":2013,"finding":"Smurf family E3 ubiquitin ligases ubiquitylate Smo and mediate its cell-surface clearance in Drosophila; GRK2-mediated phosphorylation of Smurf promotes Smo ubiquitylation by recruiting Smurf to Smo, whereas PKA-mediated phosphorylation of Smo causes Smurf to dissociate, inhibiting ubiquitylation; Smo and Ptc compete for the same Smurf pool, so Hh promotes Ptc ubiquitylation/degradation by displacing Smurf from Smo.","method":"Drosophila genetics, co-immunoprecipitation, ubiquitylation assays, phosphorylation-site mutagenesis, epistasis","journal":"Science signaling","confidence":"High","confidence_rationale":"Tier 1–2 / Strong — ubiquitylation assays, Co-IP, mutagenesis of phosphorylation sites, multiple orthogonal methods in one study","pmids":["29438012"],"is_preprint":false},{"year":2013,"finding":"The ESCRT-II component Vps36 regulates Smo trafficking between cytosol and plasma membrane by recognizing ubiquitin on Smo in the absence of Hh; Smo is ubiquitylated on its cytoplasmic loops and C-tail in the Hh-off state.","method":"Drosophila genetics, co-immunoprecipitation, ubiquitylation assays, plasma membrane accumulation assays","journal":"Journal of cell science","confidence":"High","confidence_rationale":"Tier 2 / Strong — Co-IP, ubiquitylation mapping, genetic loss-of-function, multiple orthogonal methods","pmids":["23843610"],"is_preprint":false},{"year":2014,"finding":"Ptch2 functions as a functional Shh receptor that regulates Smo localization and activity in vitro, sharing overlapping function with Ptch1; loss of Ptch2 exacerbates limb outgrowth defects in Ptch1 limb-specific knockouts in vivo.","method":"In vitro Smo localization assay, mouse genetic epistasis (Ptch1/Ptch2 double mutants), limb bud phenotype analysis","journal":"Developmental biology","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — direct localization experiment, genetic epistasis, single lab","pmids":["25448692"],"is_preprint":false},{"year":2014,"finding":"The SMO L412F mutation is an activating mutation that constitutively activates Hedgehog pathway signaling and its effect can be inhibited by arsenic trioxide (ATO).","method":"Functional reporter assay for Hedgehog pathway activity with mutant SMO constructs, ATO inhibition in ameloblastoma cells","journal":"Nature genetics","confidence":"High","confidence_rationale":"Tier 2 / Strong — functional activation assay with specific mutant, pharmacological inhibition confirming on-target effect, replicated across tumor samples","pmids":["24859340"],"is_preprint":false},{"year":2016,"finding":"Recurrent somatic mosaic SMO c.1234C>T (p.Leu412Phe) substitution constitutively activates SMO in the absence of Hh signaling and causes Curry-Jones syndrome; the same mutation is the most common activating SMO mutation found in medulloblastoma, ameloblastoma, and BCC.","method":"Targeted sequencing/Sanger sequencing across multiple tissues for mosaicism, cross-referencing with functional activation data from tumor studies","journal":"American journal of human genetics","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — genetic identification of constitutional activating variant, functional inference from prior tumor studies; no new in vitro reconstitution in this paper","pmids":["27236920"],"is_preprint":false},{"year":2017,"finding":"Arl13b, a small GTPase, binds Smo and regulates its stability, trafficking, and ciliary localization, which are required for Hedgehog signaling activation in gastric cancer cells.","method":"Co-immunoprecipitation (Arl13b–Smo), protein stability assays, Smo trafficking/localization assays, in vitro and in vivo functional assays","journal":"Cancer research","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — Co-IP, localization, stability assays, single lab","pmids":["28611043"],"is_preprint":false},{"year":2018,"finding":"TMED2 binds to SMO and retains it in the ER and Golgi compartments, preventing SMO localization to the plasma membrane; mutation of TMED2 allows SMO accumulation at the plasma membrane, recapitulating early events of HH stimulation; TMED2 functions to repress HH signal strength during neural differentiation.","method":"Genetic screen in haploid ESCs, co-immunoprecipitation (TMED2–SMO), super-resolution microscopy (ER/Golgi localization), TMED2 mutant functional analysis, neural differentiation assay","journal":"PLoS biology","confidence":"High","confidence_rationale":"Tier 1–2 / Strong — genetic screen, Co-IP, super-resolution microscopy, functional rescue, multiple orthogonal methods in one study","pmids":["35353806"],"is_preprint":false},{"year":2018,"finding":"In PTCH1-silenced keratinocytes, SMO localizes to the nucleus via a putative nuclear/nucleolar localization signal (N(o)LS), and this nuclear SMO activates GLI1 through a mechanism that is unresponsive to pharmacological SMO inhibitors; mutational inactivation of the N(o)LS ablates nuclear SMO localization and suppresses GLI1 induction.","method":"siRNA silencing, pharmacological SMO inhibition, immunofluorescence/immunohistochemistry (nuclear SMO), N(o)LS mutagenesis, gene expression analysis","journal":"Cancer research","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — direct localization experiment with functional consequence, N(o)LS mutagenesis, confirmed in human/mouse BCC tissue; single lab","pmids":["29463581"],"is_preprint":false},{"year":2019,"finding":"HERC4 E3 ubiquitin ligase binds Smo, promotes its degradation, and destabilizes the Smo oncoprotein; depletion of HERC4 increases Smo protein levels and activates Hh pathway in non-small cell lung cancer cells.","method":"Drosophila modifier screen (dHerc4/dSmo), reciprocal co-immunoprecipitation (HERC4–Smo in NSCLC), protein stability/degradation assays, Hh pathway activity readout","journal":"Biochemical and biophysical research communications","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — reciprocal Co-IP, degradation assay, Drosophila genetic screen plus mammalian validation; single lab","pmids":["31010679"],"is_preprint":false},{"year":2020,"finding":"Bi-allelic loss-of-function variants in SMO in humans cause developmental anomalies (hypothalamic hamartoma, heart defects, polydactyly, aganglionosis); patient-derived cells show normal ciliogenesis but severely altered Hh signal transduction due to either altered primary cilium trafficking or abnormal downstream activation; SMO also regulates basal ciliary trafficking of GLI2 when the pathway is off.","method":"Human genetics (bi-allelic SMO variants in 7 individuals), patient-derived cell functional assays (ciliogenesis, Hh signaling, PC trafficking of SMO/GLI2), immunofluorescence","journal":"American journal of human genetics","confidence":"High","confidence_rationale":"Tier 2 / Strong — functional cellular assays in patient-derived cells, multiple families, multiple orthogonal methods (ciliogenesis, PC trafficking, pathway activity)","pmids":["32413283"],"is_preprint":false},{"year":2010,"finding":"SMO-mediated Hedgehog signaling requires TGFβ2 as a downstream effector: activated SMO (SmoM2) upregulates TGFβ2 in keratinocytes with activated TGFβ signaling (elevated pSMAD2/3) in both tumor and stroma; TGFβ receptor I inhibitor significantly reduces tumor area in K14cre/R26SmoM2 mice.","method":"Transgenic mouse model (K14cre/R26SmoM2), gene expression analysis (TGFβ2 as Hh-regulated gene), pharmacological inhibition of TGFβ receptor I (SD208), histology","journal":"The Journal of biological chemistry","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — in vivo mouse model with pharmacological rescue, target gene identification; single lab","pmids":["20858897"],"is_preprint":false},{"year":2012,"finding":"Smo activity is required for IGF-I-induced PI3K/Akt signaling in myoblasts: cyclopamine reduces IGF-I-induced Akt phosphorylation, Smo-conditional knockout myoblasts show markedly reduced IGF-I-induced Akt and MAPK phosphorylation, and immunoprecipitation reveals that tyrosine-phosphorylated proteins including the PI3K regulatory subunit p85 and IGF-IR associate with Smo in response to Shh and IGF-I.","method":"Smo conditional knockout mice (MCre;Smo flox/flox), cyclopamine inhibition, co-immunoprecipitation (Smo–p85–IGF-IR), phospho-western blots","journal":"Journal of cellular physiology","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — Co-IP demonstrating Smo–IGF-IR–p85 complex, genetic knockout, pharmacological inhibition; single lab","pmids":["21618536"],"is_preprint":false},{"year":2021,"finding":"CD47–SIRPα interaction activates Hedgehog/SMO/Gli1 signaling in macrophages; disruption of myeloid SMO increases liver inflammation with diminished Gli1; Gli1 interacts with Notch intracellular domain (NICD) and regulates target gene Dvl2 to inhibit NEK7/NLRP3 activity.","method":"Mouse ischemia/reperfusion model, myeloid-specific SMO deletion, MSC/macrophage co-culture, Co-IP (Gli1–NICD), nuclear translocation assays, NLRP3 activity measurement","journal":"Hepatology (Baltimore, Md.)","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — myeloid SMO knockout, Co-IP (Gli1–NICD), in vivo and in vitro orthogonal methods; single lab","pmids":["33765345"],"is_preprint":false},{"year":2022,"finding":"mRNA m5C modification of SMO mRNA is recognized by ALYREF, which exports SMO mRNA from nucleus to cytoplasm, increasing SMO protein expression and promoting myogenesis; this ALYREF-m5C-SMO mechanism regulates the balance between adipogenesis and myogenesis.","method":"RNA bisulfite sequencing (m5C profiling), ALYREF binding assays, nuclear/cytoplasmic fractionation, SMO protein expression analysis, in vitro adipogenesis/myogenesis assays","journal":"Cellular and molecular life sciences : CMLS","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — m5C mapping, fractionation with functional consequence, multiple cell/tissue contexts; single lab","pmids":["35962235"],"is_preprint":false},{"year":2018,"finding":"The Wnt3a-activated β-catenin/TCF4 complex directly binds to the SMO promoter (two binding sites within 1.5 kb) and transcriptionally activates SMO expression; siRNA knockdown of β-catenin reduces SMO mRNA even under Wnt3a treatment.","method":"Chromatin immunoprecipitation (TCF4 binding to Smo promoter), yeast one-hybrid assay, TCF4/β-catenin overexpression and siRNA knockdown, RT-qPCR, western blot","journal":"Experimental and therapeutic medicine","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — ChIP and yeast one-hybrid confirming direct promoter binding, functional siRNA rescue; single lab","pmids":["30186446"],"is_preprint":false},{"year":2014,"finding":"SMO D473Y and G497W mutations confer resistance to vismodegib in BCC by distinct mechanisms: in silico modeling shows G497W causes partial obstruction of the drug entry site (conformational rearrangement), while D473Y disrupts a stabilizing hydrogen bond network at the binding site geometry.","method":"Clinical sequencing of pre/post-treatment BCC specimens, in silico molecular modeling (conformational and hydrogen bond analysis)","journal":"Molecular oncology","confidence":"Low","confidence_rationale":"Tier 4 / Weak — in silico modeling only, no in vitro reconstitution or mutagenesis functional assay","pmids":["25306392"],"is_preprint":false},{"year":2011,"finding":"Hypoxia activates Hedgehog signaling in pancreatic cancer in a ligand-independent manner by upregulating Smo transcription; silencing Smo (but not silencing Shh) decreases Gli1 and MMP9 transcription and reduces PDAC invasiveness.","method":"siRNA knockdown of Smo (vs Shh), qRT-PCR, invasion assays in hypoxic vs normoxic conditions","journal":"Cancer science","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — siRNA epistasis distinguishing Smo-dependent from Shh-dependent activation, functional invasion readout; single lab","pmids":["21338440"],"is_preprint":false},{"year":2022,"finding":"FGF18 attenuates liver fibrosis by suppressing SMO expression, and the interaction between SMO and LATS1 is crucial for FGF18-induced protective effects via the SMO–LATS1–YAP Hippo signaling axis.","method":"Co-immunoprecipitation (SMO–LATS1), FGF18 overexpression/HSC-specific deletion in vivo, western blot (SMO, pLATS1, YAP), CCl4 fibrosis model","journal":"Pharmacological research","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — Co-IP (SMO–LATS1), in vivo genetic deletion, multiple assays; single lab","pmids":["35202822"],"is_preprint":false}],"current_model":"SMO (Smoothened) is a GPCR-like seven-transmembrane signal transducer that is constitutively inhibited by Patched (PTCH1/2) and, upon Hedgehog ligand binding to PTCH, translocates to the primary cilium where it adopts an active conformation through sequential PKA/CK1-mediated C-tail phosphorylation (further amplified by GRK2/Gprk2 phosphorylation and scaffolding); its surface accumulation and degradation are controlled by Smurf E3 ubiquitin ligases (regulated by GRK2 and PKA phosphorylation), by Vps36/ESCRT-II-mediated ubiquitin-dependent trafficking, and by HERC4-mediated protein destabilization; in the ER/Golgi, TMED2 retains SMO before activation; downstream, active ciliary SMO promotes dissociation of Sufu/Gli3 complexes at the cilium tip (requiring the Evc/Evc2 complex) to shift the balance toward Gli activator forms, and its activity is modulated by interactions with the Fu–Cos2 complex (Drosophila) and by PP4 phosphatase dephosphorylation; activating mutations (e.g., L412F, W535L, D473H) constitutively activate the pathway and drive multiple cancers, while resistance to SMO antagonists (vismodegib) arises from mutations that disrupt drug-binding site geometry; SMO also engages non-canonical signaling including nuclear localization-dependent GLI1 activation and association with the IGF-IR/PI3K p85 complex, and its transcription is directly activated by the Wnt/β-catenin–TCF4 complex."},"narrative":{"mechanistic_narrative":"SMO (Smoothened) is a seven-transmembrane signal transducer that operates as the central relay of the Hedgehog (Hh) pathway, propagating the signal from the Patched receptor to downstream Gli transcription factors [PMID:16229832, PMID:25448692]. Productive signaling requires SMO localization to the primary cilium, an event dependent on intraflagellar transport; loss of the retrograde IFT motor disrupts SMO ciliary accumulation and abolishes both Gli activator and repressor output, including Gli3 proteolytic processing [PMID:16229832]. Once active in the cilium, SMO requires the Evc/Evc2 complex, with which it physically associates, to drive recruitment of Gli3 to ciliary tips and dissociation of Sufu/Gli3 complexes, shifting the balance toward Gli activator forms [PMID:23026747]. SMO activity is gated by graded C-tail phosphorylation: in Drosophila, sequential PKA/CK1 priming enables GRK2 (Gprk2) phosphorylation of Ser741/Thr742 and kinase-independent GRK2 binding that stabilizes the active conformation in a positive feedback loop, while PP4 phosphatase and the Fused–Costal2 complex counteract this to restrain surface accumulation and signaling [PMID:17671093, PMID:19088085, PMID:20844016]. SMO abundance and trafficking are further controlled by ubiquitin-dependent mechanisms: Smurf E3 ligases (regulated by GRK2 and PKA phosphorylation) and the ESCRT-II component Vps36 mediate ubiquitin-dependent surface clearance in the Hh-off state, HERC4 promotes SMO degradation, and TMED2 retains SMO in the ER/Golgi prior to activation [PMID:29438012, PMID:23843610, PMID:31010679, PMID:35353806]. In humans, activating somatic and mosaic mutations such as L412F constitutively activate the pathway and drive Curry-Jones syndrome and multiple cancers, whereas bi-allelic loss-of-function variants cause developmental anomalies including hypothalamic hamartoma and polydactyly [PMID:24859340, PMID:27236920, PMID:32413283]. Beyond canonical ciliary signaling, SMO engages non-canonical roles, including PTCH1-loss-dependent nuclear localization that activates GLI1 refractory to SMO antagonists and association with an IGF-IR/PI3K p85 complex [PMID:29463581, PMID:21618536].","teleology":[{"year":2005,"claim":"Established that SMO must traffic to the primary cilium to transduce Hedgehog signal, defining the subcellular site of pathway activation.","evidence":"Mouse retrograde IFT motor mutants with SMO ciliary immunofluorescence and Gli3 processing assays","pmids":["16229832"],"confidence":"High","gaps":["Did not define the activating conformational change SMO undergoes in the cilium","Mechanism linking ciliary SMO to Gli processing left open"]},{"year":2006,"claim":"Identified the Fused–Costal2 complex as a direct regulator of SMO phosphorylation and surface accumulation, showing SMO activity is set by an upstream kinase/scaffold network.","evidence":"Drosophila genetics, reciprocal co-IP, phosphorylation-site mapping","pmids":["17671093"],"confidence":"High","gaps":["Demonstrated in Drosophila; mammalian conservation not addressed","Did not link Cos2 binding to downstream Gli output directly"]},{"year":2008,"claim":"Showed that PP4 phosphatase opposes kinase-driven SMO phosphorylation, revealing reversible phosphorylation as the switch controlling SMO accumulation.","evidence":"In vivo Drosophila RNAi screen, domain-deletion mutagenesis, co-IP","pmids":["19088085"],"confidence":"High","gaps":["PP4 target residues on SMO not mapped","Drosophila context; mammalian PP4–SMO link untested"]},{"year":2010,"claim":"Resolved the kinase hierarchy by placing GRK2/Gprk2 phosphorylation downstream of PKA/CK1 priming and uncovering a kinase-independent stabilization feedback loop for high-level signaling.","evidence":"Drosophila genetics, phospho-site and kinase-dead mutagenesis, co-IP, epistasis","pmids":["20844016"],"confidence":"High","gaps":["Structural basis of GRK2-stabilized active conformation not determined","Conservation of Ser741/Thr742 phosphorylation in mammals untested"]},{"year":2010,"claim":"Connected active SMO to a TGFβ2 effector arm, showing SMO drives tumor growth partly through downstream TGFβ signaling in skin.","evidence":"K14cre/R26SmoM2 transgenic mice, expression analysis, TGFβ receptor inhibitor rescue","pmids":["20858897"],"confidence":"Medium","gaps":["Whether TGFβ2 induction is a direct or Gli-dependent transcriptional output unclear","Single lab; single tissue context"]},{"year":2011,"claim":"Demonstrated ligand-independent pathway activation via transcriptional upregulation of SMO under hypoxia, decoupling SMO from upstream Shh.","evidence":"siRNA knockdown of Smo vs Shh, qRT-PCR, invasion assays under hypoxia","pmids":["21338440"],"confidence":"Medium","gaps":["Transcription factor driving hypoxic SMO induction not identified","Single lab; pancreatic context only"]},{"year":2012,"claim":"Uncovered a non-canonical SMO role in IGF-I/PI3K signaling, showing SMO associates with IGF-IR and p85 independent of classical Gli output.","evidence":"Smo conditional knockout myoblasts, cyclopamine, co-IP of Smo–p85–IGF-IR, phospho-westerns","pmids":["21618536"],"confidence":"Medium","gaps":["Direct vs indirect nature of SMO–IGF-IR association not resolved","Single lab"]},{"year":2012,"claim":"Placed the Evc/Evc2 complex downstream of SMO ciliary entry, identifying the step at which SMO triggers Sufu/Gli3 dissociation at the cilium tip.","evidence":"Mouse genetics, Smo–Evc/Evc2 co-IP, ciliary immunofluorescence, Sufu-/- epistasis","pmids":["23026747"],"confidence":"High","gaps":["Molecular mechanism by which active SMO engages Evc/Evc2 unknown","Restricted to chondrocyte context"]},{"year":2013,"claim":"Defined ubiquitin-dependent control of SMO surface levels through Smurf E3 ligases and the ESCRT-II component Vps36, linking phosphorylation state to SMO trafficking and degradation.","evidence":"Drosophila genetics, ubiquitylation assays, co-IP, phospho-site mutagenesis","pmids":["29438012","23843610"],"confidence":"High","gaps":["Mammalian conservation of Smurf/Vps36 regulation of SMO untested","Ubiquitin chain types directing trafficking vs degradation not distinguished"]},{"year":2014,"claim":"Established L412F as a constitutively activating SMO mutation driving Hedgehog-dependent tumors and pharmacologically targetable by arsenic trioxide.","evidence":"Reporter assays with mutant SMO, ATO inhibition in ameloblastoma cells","pmids":["24859340"],"confidence":"High","gaps":["Structural basis of L412F constitutive activation not resolved here","ATO mechanism of inhibition not defined"]},{"year":2014,"claim":"Defined the basis of vismodegib resistance, attributing it to mutations that alter drug-binding-site geometry rather than pathway rewiring.","evidence":"Clinical sequencing of pre/post-treatment BCC, in silico molecular modeling","pmids":["25306392"],"confidence":"Low","gaps":["In silico only — no in vitro reconstitution or mutagenesis functional assay","Predicted conformational effects not biochemically validated"]},{"year":2014,"claim":"Showed Ptch2 acts as a functional Shh receptor controlling SMO localization, expanding the receptor input regulating SMO beyond Ptch1.","evidence":"In vitro SMO localization assay, Ptch1/Ptch2 double-mutant mouse epistasis","pmids":["25448692"],"confidence":"Medium","gaps":["Relative contribution of Ptch1 vs Ptch2 to SMO regulation in different tissues unclear","Single lab"]},{"year":2016,"claim":"Linked the recurrent mosaic L412F activating substitution to a defined human developmental disorder, Curry-Jones syndrome, unifying its tumor and germline phenotypes.","evidence":"Targeted/Sanger sequencing for mosaicism across tissues with cross-reference to functional tumor data","pmids":["27236920"],"confidence":"Medium","gaps":["No new in vitro reconstitution in this study","Mechanism of mosaic-stage-dependent phenotype not addressed"]},{"year":2017,"claim":"Identified Arl13b as a SMO-binding GTPase controlling SMO stability and ciliary localization in a cancer context.","evidence":"Co-IP (Arl13b–Smo), stability and trafficking assays in gastric cancer cells","pmids":["28611043"],"confidence":"Medium","gaps":["Whether Arl13b–SMO regulation is general or cancer-specific unknown","Single lab"]},{"year":2018,"claim":"Established TMED2 as an ER/Golgi retention factor that limits SMO surface delivery, defining a pre-ciliary checkpoint on signal strength.","evidence":"Haploid ESC genetic screen, TMED2–SMO co-IP, super-resolution microscopy, neural differentiation assay","pmids":["35353806"],"confidence":"High","gaps":["How Hh stimulation overcomes TMED2 retention not defined","Relationship to Patched-mediated inhibition unclear"]},{"year":2018,"claim":"Revealed a non-canonical nuclear SMO that activates GLI1 in a manner refractory to SMO antagonists, defining a drug-resistant signaling mode.","evidence":"siRNA silencing, SMO inhibition, N(o)LS mutagenesis, immunofluorescence in BCC","pmids":["29463581"],"confidence":"Medium","gaps":["Mechanism of SMO nuclear import and GLI1 activation not biochemically defined","Single lab"]},{"year":2018,"claim":"Showed SMO transcription is directly activated by the Wnt/β-catenin–TCF4 complex, providing cross-talk input that sets SMO expression levels.","evidence":"ChIP, yeast one-hybrid, β-catenin/TCF4 overexpression and siRNA, RT-qPCR","pmids":["30186446"],"confidence":"Medium","gaps":["Physiological contexts where Wnt drives SMO not established","Single lab"]},{"year":2019,"claim":"Identified HERC4 as an E3 ligase that destabilizes the SMO oncoprotein, adding a degradation arm restraining SMO levels in lung cancer.","evidence":"Drosophila modifier screen, reciprocal HERC4–Smo co-IP, degradation assays","pmids":["31010679"],"confidence":"Medium","gaps":["HERC4 ubiquitylation sites on SMO not mapped","Single lab"]},{"year":2020,"claim":"Demonstrated that bi-allelic loss-of-function SMO variants cause human developmental anomalies and that SMO regulates basal GLI2 ciliary trafficking even when the pathway is off.","evidence":"Human genetics in 7 individuals, patient-derived cell functional assays, immunofluorescence","pmids":["32413283"],"confidence":"High","gaps":["Whether trafficking vs downstream-activation defects dominate per variant not fully resolved","Basal GLI2 trafficking mechanism not detailed"]},{"year":2021,"claim":"Placed SMO downstream of CD47–SIRPα in macrophages, extending SMO signaling into innate immune/inflammatory regulation via Gli1–NICD interaction.","evidence":"Myeloid-specific SMO deletion, ischemia/reperfusion model, Gli1–NICD co-IP, NLRP3 assays","pmids":["33765345"],"confidence":"Medium","gaps":["Direct SMO partner linking CD47 to SMO not identified","Single lab"]},{"year":2022,"claim":"Connected SMO to Hippo signaling through a SMO–LATS1 interaction regulated by FGF18, implicating SMO in fibrosis via YAP control.","evidence":"SMO–LATS1 co-IP, FGF18 manipulation in vivo, CCl4 fibrosis model","pmids":["35202822"],"confidence":"Medium","gaps":["Mechanism by which SMO modulates LATS1 activity unknown","Single lab"]},{"year":2022,"claim":"Showed SMO expression is post-transcriptionally controlled by ALYREF-mediated m5C-dependent mRNA export, adding an RNA-level layer to SMO regulation in myogenesis.","evidence":"RNA bisulfite sequencing, ALYREF binding, nuclear/cytoplasmic fractionation, differentiation assays","pmids":["35962235"],"confidence":"Medium","gaps":["Generality beyond myogenic/adipogenic balance untested","Single lab"]},{"year":null,"claim":"How the diverse phosphorylation, ubiquitylation, trafficking, and non-canonical inputs are integrated into a single conformational switch in the mammalian ciliary SMO remains unresolved.","evidence":"","pmids":[],"confidence":"Medium","gaps":["No unified structural model connecting C-tail phosphorylation to active conformation in mammals","Mechanistic link between canonical ciliary SMO and non-canonical nuclear/IGF-IR/Hippo functions undefined"]}],"mechanism_profile":{"molecular_activity":[{"term_id":"GO:0060089","term_label":"molecular transducer activity","supporting_discovery_ids":[0,4,14]},{"term_id":"GO:0140110","term_label":"transcription regulator activity","supporting_discovery_ids":[12]}],"localization":[{"term_id":"GO:0005929","term_label":"cilium","supporting_discovery_ids":[0,4,14]},{"term_id":"GO:0005886","term_label":"plasma membrane","supporting_discovery_ids":[6,11]},{"term_id":"GO:0005783","term_label":"endoplasmic reticulum","supporting_discovery_ids":[11]},{"term_id":"GO:0005794","term_label":"Golgi apparatus","supporting_discovery_ids":[11]},{"term_id":"GO:0005634","term_label":"nucleus","supporting_discovery_ids":[12]}],"pathway":[{"term_id":"R-HSA-162582","term_label":"Signal Transduction","supporting_discovery_ids":[0,4,14]},{"term_id":"R-HSA-1266738","term_label":"Developmental Biology","supporting_discovery_ids":[0,14]},{"term_id":"R-HSA-1643685","term_label":"Disease","supporting_discovery_ids":[8,9,20]},{"term_id":"R-HSA-9609507","term_label":"Protein localization","supporting_discovery_ids":[6,11]}],"complexes":["Evc/Evc2 complex","Fused–Costal2 complex"],"partners":["PTCH1","PTCH2","EVC2","TMED2","ARL13B","HERC4","LATS1","IGF1R"],"other_free_text":[]}},"prefetch_data":{"uniprot":{"accession":"Q9NWM0","full_name":"Spermine oxidase","aliases":["Polyamine oxidase 1","PAO-1","PAOh1"],"length_aa":555,"mass_kda":61.8,"function":"Flavoenzyme which catalyzes the oxidation of spermine to spermidine. Can also use N(1)-acetylspermine and spermidine as substrates, with different affinity depending on the isoform (isozyme) and on the experimental conditions. Plays an important role in the regulation of polyamine intracellular concentration and has the potential to act as a determinant of cellular sensitivity to the antitumor polyamine analogs. May contribute to beta-alanine production via aldehyde dehydrogenase conversion of 3-amino-propanal","subcellular_location":"Cytoplasm; Nucleus","url":"https://www.uniprot.org/uniprotkb/Q9NWM0/entry"},"depmap":{"release":"DepMap","has_data":true,"is_common_essential":false,"resolved_as":"","url":"https://depmap.org/portal/gene/SMO","classification":"Not Classified","n_dependent_lines":4,"n_total_lines":1208,"dependency_fraction":0.0033112582781456954},"opencell":{"profiled":false,"resolved_as":"","ensg_id":"","cell_line_id":"","localizations":[],"interactors":[],"url":"https://opencell.sf.czbiohub.org/search/SMO","total_profiled":1310},"omim":[{"mim_id":"621178","title":"TRANSMEMBRANE PROTEIN 161B; TMEM161B","url":"https://www.omim.org/entry/621178"},{"mim_id":"619185","title":"JOUBERT SYNDROME 37; JBTS37","url":"https://www.omim.org/entry/619185"},{"mim_id":"617728","title":"CENTROSOMAL PROTEIN, 295-KD; CEP295","url":"https://www.omim.org/entry/617728"},{"mim_id":"617618","title":"TOG 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of American Societies for Experimental Biology","url":"https://pubmed.ncbi.nlm.nih.gov/38572590","citation_count":20,"is_preprint":false},{"pmid":"37516284","id":"PMC_37516284","title":"Enhancement of biochemical and genomic pathways through lycopene-loaded nano-liposomes: Alleviating insulin resistance, hepatic steatosis, and autophagy in obese rats with non-alcoholic fatty liver disease: Involvement of SMO, GLI-1, and PTCH-1 genes.","date":"2023","source":"Gene","url":"https://pubmed.ncbi.nlm.nih.gov/37516284","citation_count":20,"is_preprint":false},{"pmid":"16826192","id":"PMC_16826192","title":"Antisense Smo under the control of the PTCH1 promoter delivered by an adenoviral vector inhibits the growth of human pancreatic cancer.","date":"2006","source":"Gene therapy","url":"https://pubmed.ncbi.nlm.nih.gov/16826192","citation_count":20,"is_preprint":false},{"pmid":"32743904","id":"PMC_32743904","title":"The inhibition of microRNA-326 by SP1/HDAC1 contributes to proliferation and metastasis of osteosarcoma through promoting SMO expression.","date":"2020","source":"Journal of cellular and molecular medicine","url":"https://pubmed.ncbi.nlm.nih.gov/32743904","citation_count":19,"is_preprint":false},{"pmid":"32326611","id":"PMC_32326611","title":"Hedgehog Inhibitors Suppress Osteoclastogenesis in In Vitro Cultures, and Deletion of Smo in Macrophage/Osteoclast Lineage Prevents Age-Related Bone Loss.","date":"2020","source":"International journal of molecular sciences","url":"https://pubmed.ncbi.nlm.nih.gov/32326611","citation_count":19,"is_preprint":false},{"pmid":"29175550","id":"PMC_29175550","title":"Molecular modeling study on resistance of WT/D473H SMO to antagonists LDE-225 and LEQ-506.","date":"2017","source":"Pharmacological research","url":"https://pubmed.ncbi.nlm.nih.gov/29175550","citation_count":18,"is_preprint":false},{"pmid":"20842126","id":"PMC_20842126","title":"¹H nuclear magnetic resonance spectroscopy characterisation of metabolic phenotypes in the medulloblastoma of the SMO transgenic mice.","date":"2010","source":"British journal of cancer","url":"https://pubmed.ncbi.nlm.nih.gov/20842126","citation_count":18,"is_preprint":false},{"pmid":"30557039","id":"PMC_30557039","title":"Overcoming the emerging drug resistance of smoothened: an overview of small-molecule SMO antagonists with antiresistance activity.","date":"2018","source":"Future medicinal chemistry","url":"https://pubmed.ncbi.nlm.nih.gov/30557039","citation_count":17,"is_preprint":false},{"pmid":"29564556","id":"PMC_29564556","title":"Immunohistochemical evaluation of Sonic Hedgehog signaling pathway proteins (Shh, Ptch1, Ptch2, Smo, Gli1, Gli2, and Gli3) in sporadic and syndromic odontogenic keratocysts.","date":"2018","source":"Clinical oral investigations","url":"https://pubmed.ncbi.nlm.nih.gov/29564556","citation_count":17,"is_preprint":false},{"pmid":"31010679","id":"PMC_31010679","title":"HERC4 exerts an anti-tumor role through destabilizing the oncoprotein Smo.","date":"2019","source":"Biochemical and biophysical research communications","url":"https://pubmed.ncbi.nlm.nih.gov/31010679","citation_count":16,"is_preprint":false},{"pmid":"16804411","id":"PMC_16804411","title":"Aberrant expression of PTCH (patched gene) and Smo (smoothened gene) in human pancreatic cancerous tissues and its association with hyperglycemia.","date":"2006","source":"Pancreas","url":"https://pubmed.ncbi.nlm.nih.gov/16804411","citation_count":16,"is_preprint":false},{"pmid":"16596257","id":"PMC_16596257","title":"Mutation in exon 7 of PTCH deregulates SHH/PTCH/SMO signaling: possible linkage to WNT.","date":"2006","source":"International journal of molecular medicine","url":"https://pubmed.ncbi.nlm.nih.gov/16596257","citation_count":16,"is_preprint":false},{"pmid":"35353806","id":"PMC_35353806","title":"TMED2 binding restricts SMO to the ER and Golgi compartments.","date":"2022","source":"PLoS biology","url":"https://pubmed.ncbi.nlm.nih.gov/35353806","citation_count":15,"is_preprint":false},{"pmid":"34482626","id":"PMC_34482626","title":"STAT3 is required for Smo-dependent signaling and mediates Smo-targeted treatment resistance and tumorigenesis in Shh medulloblastoma.","date":"2021","source":"Molecular oncology","url":"https://pubmed.ncbi.nlm.nih.gov/34482626","citation_count":15,"is_preprint":false},{"pmid":"30543826","id":"PMC_30543826","title":"Triazoles bind the C-terminal domain of SMO: Illustration by docking and molecular dynamics simulations the binding between SMO and triazoles.","date":"2018","source":"Life sciences","url":"https://pubmed.ncbi.nlm.nih.gov/30543826","citation_count":15,"is_preprint":false},{"pmid":"30865837","id":"PMC_30865837","title":"miR-370 inhibits the angiogenic activity of endothelial cells by targeting smoothened (SMO) and bone morphogenetic protein (BMP)-2.","date":"2019","source":"FASEB journal : official publication of the Federation of American Societies for Experimental Biology","url":"https://pubmed.ncbi.nlm.nih.gov/30865837","citation_count":15,"is_preprint":false},{"pmid":"28752270","id":"PMC_28752270","title":"Combination treatment with dendrosomal nanocurcumin and doxorubicin improves anticancer effects on breast cancer cells through modulating CXCR4/NF-κB/Smo regulatory network.","date":"2017","source":"Molecular biology reports","url":"https://pubmed.ncbi.nlm.nih.gov/28752270","citation_count":15,"is_preprint":false},{"pmid":"29463581","id":"PMC_29463581","title":"A Novel Mechanism for Activation of GLI1 by Nuclear SMO That Escapes Anti-SMO Inhibitors.","date":"2018","source":"Cancer research","url":"https://pubmed.ncbi.nlm.nih.gov/29463581","citation_count":14,"is_preprint":false},{"pmid":"32841701","id":"PMC_32841701","title":"Scutellariabarbata D. Don extraction selectively targets stemness-prone NSCLC cells by attenuating SOX2/SMO/GLI1 network loop.","date":"2020","source":"Journal of ethnopharmacology","url":"https://pubmed.ncbi.nlm.nih.gov/32841701","citation_count":14,"is_preprint":false},{"pmid":"32063403","id":"PMC_32063403","title":"Design, synthesis and biological evaluation of anthranilamide derivatives as potent SMO inhibitors.","date":"2020","source":"Bioorganic & medicinal chemistry","url":"https://pubmed.ncbi.nlm.nih.gov/32063403","citation_count":13,"is_preprint":false},{"pmid":"38160216","id":"PMC_38160216","title":"Purmorphamine, a Smo-Shh/Gli Activator, Promotes Sonic Hedgehog-Mediated Neurogenesis and Restores Behavioural and Neurochemical Deficits in Experimental Model of Multiple Sclerosis.","date":"2023","source":"Neurochemical research","url":"https://pubmed.ncbi.nlm.nih.gov/38160216","citation_count":13,"is_preprint":false},{"pmid":"31981861","id":"PMC_31981861","title":"miR-135a Inhibits the Invasion and Migration of Esophageal Cancer Stem Cells through the Hedgehog Signaling Pathway by Targeting Smo.","date":"2019","source":"Molecular therapy. Nucleic acids","url":"https://pubmed.ncbi.nlm.nih.gov/31981861","citation_count":13,"is_preprint":false},{"pmid":"30186446","id":"PMC_30186446","title":"Wnt3a-regulated TCF4/β-catenin complex directly activates the key Hedgehog signalling genes Smo and Gli1.","date":"2018","source":"Experimental and therapeutic medicine","url":"https://pubmed.ncbi.nlm.nih.gov/30186446","citation_count":13,"is_preprint":false},{"pmid":"30497210","id":"PMC_30497210","title":"A familial syndrome of hypothalamic hamartomas, polydactyly, and SMO mutations: a clinical report of 2 cases.","date":"2018","source":"Journal of neurosurgery. Pediatrics","url":"https://pubmed.ncbi.nlm.nih.gov/30497210","citation_count":13,"is_preprint":false}],"cost":{"stage1":{"model":"claude-sonnet-4-6","input_tokens":50705,"output_tokens":5970,"usd":0.120832,"stage1_stop_reason":"end_turn"},"stage2":{"model":"claude-opus-4-8","input_tokens":14676,"output_tokens":6080,"usd":0.11269,"stage2_stop_reason":"end_turn"},"total_usd":0.233522,"stage1_batch_id":"msgbatch_013LWZZT6MWaqB9qyTSeQBmU","stage2_batch_id":"msgbatch_0194ZzQaTGNpruoNJBbEMbt3","note":"batch pricing = 50% of standard"},"stage1_raw":"```json\n{\n  \"discoveries\": [\n    {\n      \"year\": 2005,\n      \"finding\": \"Localization of Smo to primary cilia is required for Hedgehog signal transduction; loss of the retrograde IFT motor (Dnchc2) disrupts Smo ciliary localization and prevents both Gli activator and repressor function, as well as effective proteolytic processing of Gli3.\",\n      \"method\": \"Mouse genetics (retrograde IFT motor mutants), immunofluorescence localization of Smo to primary cilia, Gli3 processing assay\",\n      \"journal\": \"Developmental biology\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — direct localization experiment with functional consequence (Gli activator/repressor loss), replicated across multiple genetic backgrounds in vivo\",\n      \"pmids\": [\"16229832\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2006,\n      \"finding\": \"Fused (Fu) and Costal2 (Cos2) form a complex that regulates Smo phosphorylation and cell-surface accumulation in Drosophila: Cos2 binds Smo C-terminal domain to block Hh-induced phosphorylation, while Fu phosphorylates Cos2 at Ser572 to attenuate Cos2–Smo interaction and promote Smo surface accumulation.\",\n      \"method\": \"Drosophila genetics (fu mutant clones, dominant-negative Fu), co-immunoprecipitation, epistasis analysis, phosphorylation mapping\",\n      \"journal\": \"Genes & development\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — reciprocal co-IP, genetic epistasis, phosphorylation-site mapping, multiple orthogonal methods in one study\",\n      \"pmids\": [\"17671093\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2008,\n      \"finding\": \"PP4 phosphatase counteracts kinase-mediated phosphorylation of Smo in Drosophila: RNAi knockdown of PP4 elevates Smo phosphorylation and accumulation, increasing Hh signaling; deletion of a PP4-interaction domain (aa 626–678) in Smo promotes Smo phosphorylation and signaling; Hh downregulates the Smo–PP4 interaction, which is mediated by Cos2.\",\n      \"method\": \"In vivo RNAi screen in Drosophila, domain-deletion mutagenesis, co-immunoprecipitation, Hh pathway activity assays\",\n      \"journal\": \"Development (Cambridge, England)\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — in vivo RNAi screen, domain deletion mutagenesis, Co-IP, multiple orthogonal methods\",\n      \"pmids\": [\"19088085\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2010,\n      \"finding\": \"GRK2 (Gprk2) promotes high-level Hedgehog signaling in Drosophila by phosphorylating Smo C-tail at Ser741/Thr742, facilitated by prior PKA and CK1 phosphorylation; additionally, Gprk2 dimerizes/oligomerizes and binds Smo C-tail in a kinase-independent manner to stabilize the active Smo conformation, forming a positive feedback loop downstream of PKA and CK1.\",\n      \"method\": \"Drosophila genetics, phosphorylation-site mutagenesis, co-immunoprecipitation, kinase-dead constructs, epistasis analysis\",\n      \"journal\": \"Genes & development\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1–2 / Strong — mutagenesis of phosphorylation sites, kinase-dead constructs, Co-IP, epistasis, multiple orthogonal methods\",\n      \"pmids\": [\"20844016\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2012,\n      \"finding\": \"The Evc/Evc2 complex co-precipitates with Smo and is required for Hh signaling downstream of Smo ciliary translocation in chondrocytes: Smo translocation to the cilium is normal in Evc2-deficient cells after SAG treatment, but Gli3 recruitment to cilia tips and Sufu/Gli3 dissociation are impaired, and Evc silencing in Sufu−/− cells attenuates Hh output.\",\n      \"method\": \"Mouse genetic models, co-immunoprecipitation (Smo–Evc/Evc2), immunofluorescence (ciliary localization), Sufu−/− epistasis\",\n      \"journal\": \"Human molecular genetics\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — reciprocal Co-IP, direct ciliary localization imaging, genetic epistasis in multiple mutant backgrounds\",\n      \"pmids\": [\"23026747\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2013,\n      \"finding\": \"Smurf family E3 ubiquitin ligases ubiquitylate Smo and mediate its cell-surface clearance in Drosophila; GRK2-mediated phosphorylation of Smurf promotes Smo ubiquitylation by recruiting Smurf to Smo, whereas PKA-mediated phosphorylation of Smo causes Smurf to dissociate, inhibiting ubiquitylation; Smo and Ptc compete for the same Smurf pool, so Hh promotes Ptc ubiquitylation/degradation by displacing Smurf from Smo.\",\n      \"method\": \"Drosophila genetics, co-immunoprecipitation, ubiquitylation assays, phosphorylation-site mutagenesis, epistasis\",\n      \"journal\": \"Science signaling\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1–2 / Strong — ubiquitylation assays, Co-IP, mutagenesis of phosphorylation sites, multiple orthogonal methods in one study\",\n      \"pmids\": [\"29438012\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2013,\n      \"finding\": \"The ESCRT-II component Vps36 regulates Smo trafficking between cytosol and plasma membrane by recognizing ubiquitin on Smo in the absence of Hh; Smo is ubiquitylated on its cytoplasmic loops and C-tail in the Hh-off state.\",\n      \"method\": \"Drosophila genetics, co-immunoprecipitation, ubiquitylation assays, plasma membrane accumulation assays\",\n      \"journal\": \"Journal of cell science\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — Co-IP, ubiquitylation mapping, genetic loss-of-function, multiple orthogonal methods\",\n      \"pmids\": [\"23843610\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2014,\n      \"finding\": \"Ptch2 functions as a functional Shh receptor that regulates Smo localization and activity in vitro, sharing overlapping function with Ptch1; loss of Ptch2 exacerbates limb outgrowth defects in Ptch1 limb-specific knockouts in vivo.\",\n      \"method\": \"In vitro Smo localization assay, mouse genetic epistasis (Ptch1/Ptch2 double mutants), limb bud phenotype analysis\",\n      \"journal\": \"Developmental biology\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — direct localization experiment, genetic epistasis, single lab\",\n      \"pmids\": [\"25448692\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2014,\n      \"finding\": \"The SMO L412F mutation is an activating mutation that constitutively activates Hedgehog pathway signaling and its effect can be inhibited by arsenic trioxide (ATO).\",\n      \"method\": \"Functional reporter assay for Hedgehog pathway activity with mutant SMO constructs, ATO inhibition in ameloblastoma cells\",\n      \"journal\": \"Nature genetics\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — functional activation assay with specific mutant, pharmacological inhibition confirming on-target effect, replicated across tumor samples\",\n      \"pmids\": [\"24859340\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2016,\n      \"finding\": \"Recurrent somatic mosaic SMO c.1234C>T (p.Leu412Phe) substitution constitutively activates SMO in the absence of Hh signaling and causes Curry-Jones syndrome; the same mutation is the most common activating SMO mutation found in medulloblastoma, ameloblastoma, and BCC.\",\n      \"method\": \"Targeted sequencing/Sanger sequencing across multiple tissues for mosaicism, cross-referencing with functional activation data from tumor studies\",\n      \"journal\": \"American journal of human genetics\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — genetic identification of constitutional activating variant, functional inference from prior tumor studies; no new in vitro reconstitution in this paper\",\n      \"pmids\": [\"27236920\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2017,\n      \"finding\": \"Arl13b, a small GTPase, binds Smo and regulates its stability, trafficking, and ciliary localization, which are required for Hedgehog signaling activation in gastric cancer cells.\",\n      \"method\": \"Co-immunoprecipitation (Arl13b–Smo), protein stability assays, Smo trafficking/localization assays, in vitro and in vivo functional assays\",\n      \"journal\": \"Cancer research\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — Co-IP, localization, stability assays, single lab\",\n      \"pmids\": [\"28611043\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2018,\n      \"finding\": \"TMED2 binds to SMO and retains it in the ER and Golgi compartments, preventing SMO localization to the plasma membrane; mutation of TMED2 allows SMO accumulation at the plasma membrane, recapitulating early events of HH stimulation; TMED2 functions to repress HH signal strength during neural differentiation.\",\n      \"method\": \"Genetic screen in haploid ESCs, co-immunoprecipitation (TMED2–SMO), super-resolution microscopy (ER/Golgi localization), TMED2 mutant functional analysis, neural differentiation assay\",\n      \"journal\": \"PLoS biology\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1–2 / Strong — genetic screen, Co-IP, super-resolution microscopy, functional rescue, multiple orthogonal methods in one study\",\n      \"pmids\": [\"35353806\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2018,\n      \"finding\": \"In PTCH1-silenced keratinocytes, SMO localizes to the nucleus via a putative nuclear/nucleolar localization signal (N(o)LS), and this nuclear SMO activates GLI1 through a mechanism that is unresponsive to pharmacological SMO inhibitors; mutational inactivation of the N(o)LS ablates nuclear SMO localization and suppresses GLI1 induction.\",\n      \"method\": \"siRNA silencing, pharmacological SMO inhibition, immunofluorescence/immunohistochemistry (nuclear SMO), N(o)LS mutagenesis, gene expression analysis\",\n      \"journal\": \"Cancer research\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — direct localization experiment with functional consequence, N(o)LS mutagenesis, confirmed in human/mouse BCC tissue; single lab\",\n      \"pmids\": [\"29463581\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2019,\n      \"finding\": \"HERC4 E3 ubiquitin ligase binds Smo, promotes its degradation, and destabilizes the Smo oncoprotein; depletion of HERC4 increases Smo protein levels and activates Hh pathway in non-small cell lung cancer cells.\",\n      \"method\": \"Drosophila modifier screen (dHerc4/dSmo), reciprocal co-immunoprecipitation (HERC4–Smo in NSCLC), protein stability/degradation assays, Hh pathway activity readout\",\n      \"journal\": \"Biochemical and biophysical research communications\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — reciprocal Co-IP, degradation assay, Drosophila genetic screen plus mammalian validation; single lab\",\n      \"pmids\": [\"31010679\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2020,\n      \"finding\": \"Bi-allelic loss-of-function variants in SMO in humans cause developmental anomalies (hypothalamic hamartoma, heart defects, polydactyly, aganglionosis); patient-derived cells show normal ciliogenesis but severely altered Hh signal transduction due to either altered primary cilium trafficking or abnormal downstream activation; SMO also regulates basal ciliary trafficking of GLI2 when the pathway is off.\",\n      \"method\": \"Human genetics (bi-allelic SMO variants in 7 individuals), patient-derived cell functional assays (ciliogenesis, Hh signaling, PC trafficking of SMO/GLI2), immunofluorescence\",\n      \"journal\": \"American journal of human genetics\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — functional cellular assays in patient-derived cells, multiple families, multiple orthogonal methods (ciliogenesis, PC trafficking, pathway activity)\",\n      \"pmids\": [\"32413283\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2010,\n      \"finding\": \"SMO-mediated Hedgehog signaling requires TGFβ2 as a downstream effector: activated SMO (SmoM2) upregulates TGFβ2 in keratinocytes with activated TGFβ signaling (elevated pSMAD2/3) in both tumor and stroma; TGFβ receptor I inhibitor significantly reduces tumor area in K14cre/R26SmoM2 mice.\",\n      \"method\": \"Transgenic mouse model (K14cre/R26SmoM2), gene expression analysis (TGFβ2 as Hh-regulated gene), pharmacological inhibition of TGFβ receptor I (SD208), histology\",\n      \"journal\": \"The Journal of biological chemistry\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — in vivo mouse model with pharmacological rescue, target gene identification; single lab\",\n      \"pmids\": [\"20858897\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2012,\n      \"finding\": \"Smo activity is required for IGF-I-induced PI3K/Akt signaling in myoblasts: cyclopamine reduces IGF-I-induced Akt phosphorylation, Smo-conditional knockout myoblasts show markedly reduced IGF-I-induced Akt and MAPK phosphorylation, and immunoprecipitation reveals that tyrosine-phosphorylated proteins including the PI3K regulatory subunit p85 and IGF-IR associate with Smo in response to Shh and IGF-I.\",\n      \"method\": \"Smo conditional knockout mice (MCre;Smo flox/flox), cyclopamine inhibition, co-immunoprecipitation (Smo–p85–IGF-IR), phospho-western blots\",\n      \"journal\": \"Journal of cellular physiology\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — Co-IP demonstrating Smo–IGF-IR–p85 complex, genetic knockout, pharmacological inhibition; single lab\",\n      \"pmids\": [\"21618536\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2021,\n      \"finding\": \"CD47–SIRPα interaction activates Hedgehog/SMO/Gli1 signaling in macrophages; disruption of myeloid SMO increases liver inflammation with diminished Gli1; Gli1 interacts with Notch intracellular domain (NICD) and regulates target gene Dvl2 to inhibit NEK7/NLRP3 activity.\",\n      \"method\": \"Mouse ischemia/reperfusion model, myeloid-specific SMO deletion, MSC/macrophage co-culture, Co-IP (Gli1–NICD), nuclear translocation assays, NLRP3 activity measurement\",\n      \"journal\": \"Hepatology (Baltimore, Md.)\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — myeloid SMO knockout, Co-IP (Gli1–NICD), in vivo and in vitro orthogonal methods; single lab\",\n      \"pmids\": [\"33765345\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2022,\n      \"finding\": \"mRNA m5C modification of SMO mRNA is recognized by ALYREF, which exports SMO mRNA from nucleus to cytoplasm, increasing SMO protein expression and promoting myogenesis; this ALYREF-m5C-SMO mechanism regulates the balance between adipogenesis and myogenesis.\",\n      \"method\": \"RNA bisulfite sequencing (m5C profiling), ALYREF binding assays, nuclear/cytoplasmic fractionation, SMO protein expression analysis, in vitro adipogenesis/myogenesis assays\",\n      \"journal\": \"Cellular and molecular life sciences : CMLS\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — m5C mapping, fractionation with functional consequence, multiple cell/tissue contexts; single lab\",\n      \"pmids\": [\"35962235\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2018,\n      \"finding\": \"The Wnt3a-activated β-catenin/TCF4 complex directly binds to the SMO promoter (two binding sites within 1.5 kb) and transcriptionally activates SMO expression; siRNA knockdown of β-catenin reduces SMO mRNA even under Wnt3a treatment.\",\n      \"method\": \"Chromatin immunoprecipitation (TCF4 binding to Smo promoter), yeast one-hybrid assay, TCF4/β-catenin overexpression and siRNA knockdown, RT-qPCR, western blot\",\n      \"journal\": \"Experimental and therapeutic medicine\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — ChIP and yeast one-hybrid confirming direct promoter binding, functional siRNA rescue; single lab\",\n      \"pmids\": [\"30186446\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2014,\n      \"finding\": \"SMO D473Y and G497W mutations confer resistance to vismodegib in BCC by distinct mechanisms: in silico modeling shows G497W causes partial obstruction of the drug entry site (conformational rearrangement), while D473Y disrupts a stabilizing hydrogen bond network at the binding site geometry.\",\n      \"method\": \"Clinical sequencing of pre/post-treatment BCC specimens, in silico molecular modeling (conformational and hydrogen bond analysis)\",\n      \"journal\": \"Molecular oncology\",\n      \"confidence\": \"Low\",\n      \"confidence_rationale\": \"Tier 4 / Weak — in silico modeling only, no in vitro reconstitution or mutagenesis functional assay\",\n      \"pmids\": [\"25306392\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2011,\n      \"finding\": \"Hypoxia activates Hedgehog signaling in pancreatic cancer in a ligand-independent manner by upregulating Smo transcription; silencing Smo (but not silencing Shh) decreases Gli1 and MMP9 transcription and reduces PDAC invasiveness.\",\n      \"method\": \"siRNA knockdown of Smo (vs Shh), qRT-PCR, invasion assays in hypoxic vs normoxic conditions\",\n      \"journal\": \"Cancer science\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — siRNA epistasis distinguishing Smo-dependent from Shh-dependent activation, functional invasion readout; single lab\",\n      \"pmids\": [\"21338440\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2022,\n      \"finding\": \"FGF18 attenuates liver fibrosis by suppressing SMO expression, and the interaction between SMO and LATS1 is crucial for FGF18-induced protective effects via the SMO–LATS1–YAP Hippo signaling axis.\",\n      \"method\": \"Co-immunoprecipitation (SMO–LATS1), FGF18 overexpression/HSC-specific deletion in vivo, western blot (SMO, pLATS1, YAP), CCl4 fibrosis model\",\n      \"journal\": \"Pharmacological research\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — Co-IP (SMO–LATS1), in vivo genetic deletion, multiple assays; single lab\",\n      \"pmids\": [\"35202822\"],\n      \"is_preprint\": false\n    }\n  ],\n  \"current_model\": \"SMO (Smoothened) is a GPCR-like seven-transmembrane signal transducer that is constitutively inhibited by Patched (PTCH1/2) and, upon Hedgehog ligand binding to PTCH, translocates to the primary cilium where it adopts an active conformation through sequential PKA/CK1-mediated C-tail phosphorylation (further amplified by GRK2/Gprk2 phosphorylation and scaffolding); its surface accumulation and degradation are controlled by Smurf E3 ubiquitin ligases (regulated by GRK2 and PKA phosphorylation), by Vps36/ESCRT-II-mediated ubiquitin-dependent trafficking, and by HERC4-mediated protein destabilization; in the ER/Golgi, TMED2 retains SMO before activation; downstream, active ciliary SMO promotes dissociation of Sufu/Gli3 complexes at the cilium tip (requiring the Evc/Evc2 complex) to shift the balance toward Gli activator forms, and its activity is modulated by interactions with the Fu–Cos2 complex (Drosophila) and by PP4 phosphatase dephosphorylation; activating mutations (e.g., L412F, W535L, D473H) constitutively activate the pathway and drive multiple cancers, while resistance to SMO antagonists (vismodegib) arises from mutations that disrupt drug-binding site geometry; SMO also engages non-canonical signaling including nuclear localization-dependent GLI1 activation and association with the IGF-IR/PI3K p85 complex, and its transcription is directly activated by the Wnt/β-catenin–TCF4 complex.\"\n}\n```","stage2_raw":"{\n  \"mechanistic_narrative\": \"SMO (Smoothened) is a seven-transmembrane signal transducer that operates as the central relay of the Hedgehog (Hh) pathway, propagating the signal from the Patched receptor to downstream Gli transcription factors [#0, #7]. Productive signaling requires SMO localization to the primary cilium, an event dependent on intraflagellar transport; loss of the retrograde IFT motor disrupts SMO ciliary accumulation and abolishes both Gli activator and repressor output, including Gli3 proteolytic processing [#0]. Once active in the cilium, SMO requires the Evc/Evc2 complex, with which it physically associates, to drive recruitment of Gli3 to ciliary tips and dissociation of Sufu/Gli3 complexes, shifting the balance toward Gli activator forms [#4]. SMO activity is gated by graded C-tail phosphorylation: in Drosophila, sequential PKA/CK1 priming enables GRK2 (Gprk2) phosphorylation of Ser741/Thr742 and kinase-independent GRK2 binding that stabilizes the active conformation in a positive feedback loop, while PP4 phosphatase and the Fused–Costal2 complex counteract this to restrain surface accumulation and signaling [#1, #2, #3]. SMO abundance and trafficking are further controlled by ubiquitin-dependent mechanisms: Smurf E3 ligases (regulated by GRK2 and PKA phosphorylation) and the ESCRT-II component Vps36 mediate ubiquitin-dependent surface clearance in the Hh-off state, HERC4 promotes SMO degradation, and TMED2 retains SMO in the ER/Golgi prior to activation [#5, #6, #13, #11]. In humans, activating somatic and mosaic mutations such as L412F constitutively activate the pathway and drive Curry-Jones syndrome and multiple cancers, whereas bi-allelic loss-of-function variants cause developmental anomalies including hypothalamic hamartoma and polydactyly [#8, #9, #14]. Beyond canonical ciliary signaling, SMO engages non-canonical roles, including PTCH1-loss-dependent nuclear localization that activates GLI1 refractory to SMO antagonists and association with an IGF-IR/PI3K p85 complex [#12, #16].\",\n  \"teleology\": [\n    {\n      \"year\": 2005,\n      \"claim\": \"Established that SMO must traffic to the primary cilium to transduce Hedgehog signal, defining the subcellular site of pathway activation.\",\n      \"evidence\": \"Mouse retrograde IFT motor mutants with SMO ciliary immunofluorescence and Gli3 processing assays\",\n      \"pmids\": [\"16229832\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Did not define the activating conformational change SMO undergoes in the cilium\", \"Mechanism linking ciliary SMO to Gli processing left open\"]\n    },\n    {\n      \"year\": 2006,\n      \"claim\": \"Identified the Fused–Costal2 complex as a direct regulator of SMO phosphorylation and surface accumulation, showing SMO activity is set by an upstream kinase/scaffold network.\",\n      \"evidence\": \"Drosophila genetics, reciprocal co-IP, phosphorylation-site mapping\",\n      \"pmids\": [\"17671093\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Demonstrated in Drosophila; mammalian conservation not addressed\", \"Did not link Cos2 binding to downstream Gli output directly\"]\n    },\n    {\n      \"year\": 2008,\n      \"claim\": \"Showed that PP4 phosphatase opposes kinase-driven SMO phosphorylation, revealing reversible phosphorylation as the switch controlling SMO accumulation.\",\n      \"evidence\": \"In vivo Drosophila RNAi screen, domain-deletion mutagenesis, co-IP\",\n      \"pmids\": [\"19088085\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"PP4 target residues on SMO not mapped\", \"Drosophila context; mammalian PP4–SMO link untested\"]\n    },\n    {\n      \"year\": 2010,\n      \"claim\": \"Resolved the kinase hierarchy by placing GRK2/Gprk2 phosphorylation downstream of PKA/CK1 priming and uncovering a kinase-independent stabilization feedback loop for high-level signaling.\",\n      \"evidence\": \"Drosophila genetics, phospho-site and kinase-dead mutagenesis, co-IP, epistasis\",\n      \"pmids\": [\"20844016\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Structural basis of GRK2-stabilized active conformation not determined\", \"Conservation of Ser741/Thr742 phosphorylation in mammals untested\"]\n    },\n    {\n      \"year\": 2010,\n      \"claim\": \"Connected active SMO to a TGFβ2 effector arm, showing SMO drives tumor growth partly through downstream TGFβ signaling in skin.\",\n      \"evidence\": \"K14cre/R26SmoM2 transgenic mice, expression analysis, TGFβ receptor inhibitor rescue\",\n      \"pmids\": [\"20858897\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Whether TGFβ2 induction is a direct or Gli-dependent transcriptional output unclear\", \"Single lab; single tissue context\"]\n    },\n    {\n      \"year\": 2011,\n      \"claim\": \"Demonstrated ligand-independent pathway activation via transcriptional upregulation of SMO under hypoxia, decoupling SMO from upstream Shh.\",\n      \"evidence\": \"siRNA knockdown of Smo vs Shh, qRT-PCR, invasion assays under hypoxia\",\n      \"pmids\": [\"21338440\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Transcription factor driving hypoxic SMO induction not identified\", \"Single lab; pancreatic context only\"]\n    },\n    {\n      \"year\": 2012,\n      \"claim\": \"Uncovered a non-canonical SMO role in IGF-I/PI3K signaling, showing SMO associates with IGF-IR and p85 independent of classical Gli output.\",\n      \"evidence\": \"Smo conditional knockout myoblasts, cyclopamine, co-IP of Smo–p85–IGF-IR, phospho-westerns\",\n      \"pmids\": [\"21618536\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Direct vs indirect nature of SMO–IGF-IR association not resolved\", \"Single lab\"]\n    },\n    {\n      \"year\": 2012,\n      \"claim\": \"Placed the Evc/Evc2 complex downstream of SMO ciliary entry, identifying the step at which SMO triggers Sufu/Gli3 dissociation at the cilium tip.\",\n      \"evidence\": \"Mouse genetics, Smo–Evc/Evc2 co-IP, ciliary immunofluorescence, Sufu-/- epistasis\",\n      \"pmids\": [\"23026747\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Molecular mechanism by which active SMO engages Evc/Evc2 unknown\", \"Restricted to chondrocyte context\"]\n    },\n    {\n      \"year\": 2013,\n      \"claim\": \"Defined ubiquitin-dependent control of SMO surface levels through Smurf E3 ligases and the ESCRT-II component Vps36, linking phosphorylation state to SMO trafficking and degradation.\",\n      \"evidence\": \"Drosophila genetics, ubiquitylation assays, co-IP, phospho-site mutagenesis\",\n      \"pmids\": [\"29438012\", \"23843610\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Mammalian conservation of Smurf/Vps36 regulation of SMO untested\", \"Ubiquitin chain types directing trafficking vs degradation not distinguished\"]\n    },\n    {\n      \"year\": 2014,\n      \"claim\": \"Established L412F as a constitutively activating SMO mutation driving Hedgehog-dependent tumors and pharmacologically targetable by arsenic trioxide.\",\n      \"evidence\": \"Reporter assays with mutant SMO, ATO inhibition in ameloblastoma cells\",\n      \"pmids\": [\"24859340\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Structural basis of L412F constitutive activation not resolved here\", \"ATO mechanism of inhibition not defined\"]\n    },\n    {\n      \"year\": 2014,\n      \"claim\": \"Defined the basis of vismodegib resistance, attributing it to mutations that alter drug-binding-site geometry rather than pathway rewiring.\",\n      \"evidence\": \"Clinical sequencing of pre/post-treatment BCC, in silico molecular modeling\",\n      \"pmids\": [\"25306392\"],\n      \"confidence\": \"Low\",\n      \"gaps\": [\"In silico only — no in vitro reconstitution or mutagenesis functional assay\", \"Predicted conformational effects not biochemically validated\"]\n    },\n    {\n      \"year\": 2014,\n      \"claim\": \"Showed Ptch2 acts as a functional Shh receptor controlling SMO localization, expanding the receptor input regulating SMO beyond Ptch1.\",\n      \"evidence\": \"In vitro SMO localization assay, Ptch1/Ptch2 double-mutant mouse epistasis\",\n      \"pmids\": [\"25448692\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Relative contribution of Ptch1 vs Ptch2 to SMO regulation in different tissues unclear\", \"Single lab\"]\n    },\n    {\n      \"year\": 2016,\n      \"claim\": \"Linked the recurrent mosaic L412F activating substitution to a defined human developmental disorder, Curry-Jones syndrome, unifying its tumor and germline phenotypes.\",\n      \"evidence\": \"Targeted/Sanger sequencing for mosaicism across tissues with cross-reference to functional tumor data\",\n      \"pmids\": [\"27236920\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"No new in vitro reconstitution in this study\", \"Mechanism of mosaic-stage-dependent phenotype not addressed\"]\n    },\n    {\n      \"year\": 2017,\n      \"claim\": \"Identified Arl13b as a SMO-binding GTPase controlling SMO stability and ciliary localization in a cancer context.\",\n      \"evidence\": \"Co-IP (Arl13b–Smo), stability and trafficking assays in gastric cancer cells\",\n      \"pmids\": [\"28611043\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Whether Arl13b–SMO regulation is general or cancer-specific unknown\", \"Single lab\"]\n    },\n    {\n      \"year\": 2018,\n      \"claim\": \"Established TMED2 as an ER/Golgi retention factor that limits SMO surface delivery, defining a pre-ciliary checkpoint on signal strength.\",\n      \"evidence\": \"Haploid ESC genetic screen, TMED2–SMO co-IP, super-resolution microscopy, neural differentiation assay\",\n      \"pmids\": [\"35353806\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"How Hh stimulation overcomes TMED2 retention not defined\", \"Relationship to Patched-mediated inhibition unclear\"]\n    },\n    {\n      \"year\": 2018,\n      \"claim\": \"Revealed a non-canonical nuclear SMO that activates GLI1 in a manner refractory to SMO antagonists, defining a drug-resistant signaling mode.\",\n      \"evidence\": \"siRNA silencing, SMO inhibition, N(o)LS mutagenesis, immunofluorescence in BCC\",\n      \"pmids\": [\"29463581\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Mechanism of SMO nuclear import and GLI1 activation not biochemically defined\", \"Single lab\"]\n    },\n    {\n      \"year\": 2018,\n      \"claim\": \"Showed SMO transcription is directly activated by the Wnt/β-catenin–TCF4 complex, providing cross-talk input that sets SMO expression levels.\",\n      \"evidence\": \"ChIP, yeast one-hybrid, β-catenin/TCF4 overexpression and siRNA, RT-qPCR\",\n      \"pmids\": [\"30186446\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Physiological contexts where Wnt drives SMO not established\", \"Single lab\"]\n    },\n    {\n      \"year\": 2019,\n      \"claim\": \"Identified HERC4 as an E3 ligase that destabilizes the SMO oncoprotein, adding a degradation arm restraining SMO levels in lung cancer.\",\n      \"evidence\": \"Drosophila modifier screen, reciprocal HERC4–Smo co-IP, degradation assays\",\n      \"pmids\": [\"31010679\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"HERC4 ubiquitylation sites on SMO not mapped\", \"Single lab\"]\n    },\n    {\n      \"year\": 2020,\n      \"claim\": \"Demonstrated that bi-allelic loss-of-function SMO variants cause human developmental anomalies and that SMO regulates basal GLI2 ciliary trafficking even when the pathway is off.\",\n      \"evidence\": \"Human genetics in 7 individuals, patient-derived cell functional assays, immunofluorescence\",\n      \"pmids\": [\"32413283\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Whether trafficking vs downstream-activation defects dominate per variant not fully resolved\", \"Basal GLI2 trafficking mechanism not detailed\"]\n    },\n    {\n      \"year\": 2021,\n      \"claim\": \"Placed SMO downstream of CD47–SIRPα in macrophages, extending SMO signaling into innate immune/inflammatory regulation via Gli1–NICD interaction.\",\n      \"evidence\": \"Myeloid-specific SMO deletion, ischemia/reperfusion model, Gli1–NICD co-IP, NLRP3 assays\",\n      \"pmids\": [\"33765345\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Direct SMO partner linking CD47 to SMO not identified\", \"Single lab\"]\n    },\n    {\n      \"year\": 2022,\n      \"claim\": \"Connected SMO to Hippo signaling through a SMO–LATS1 interaction regulated by FGF18, implicating SMO in fibrosis via YAP control.\",\n      \"evidence\": \"SMO–LATS1 co-IP, FGF18 manipulation in vivo, CCl4 fibrosis model\",\n      \"pmids\": [\"35202822\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Mechanism by which SMO modulates LATS1 activity unknown\", \"Single lab\"]\n    },\n    {\n      \"year\": 2022,\n      \"claim\": \"Showed SMO expression is post-transcriptionally controlled by ALYREF-mediated m5C-dependent mRNA export, adding an RNA-level layer to SMO regulation in myogenesis.\",\n      \"evidence\": \"RNA bisulfite sequencing, ALYREF binding, nuclear/cytoplasmic fractionation, differentiation assays\",\n      \"pmids\": [\"35962235\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Generality beyond myogenic/adipogenic balance untested\", \"Single lab\"]\n    },\n    {\n      \"year\": null,\n      \"claim\": \"How the diverse phosphorylation, ubiquitylation, trafficking, and non-canonical inputs are integrated into a single conformational switch in the mammalian ciliary SMO remains unresolved.\",\n      \"evidence\": \"\",\n      \"pmids\": [],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"No unified structural model connecting C-tail phosphorylation to active conformation in mammals\", \"Mechanistic link between canonical ciliary SMO and non-canonical nuclear/IGF-IR/Hippo functions undefined\"]\n    }\n  ],\n  \"mechanism_profile\": {\n    \"molecular_activity\": [\n      {\"term_id\": \"GO:0060089\", \"supporting_discovery_ids\": [0, 4, 14]},\n      {\"term_id\": \"GO:0140110\", \"supporting_discovery_ids\": [12]}\n    ],\n    \"localization\": [\n      {\"term_id\": \"GO:0005929\", \"supporting_discovery_ids\": [0, 4, 14]},\n      {\"term_id\": \"GO:0005886\", \"supporting_discovery_ids\": [6, 11]},\n      {\"term_id\": \"GO:0005783\", \"supporting_discovery_ids\": [11]},\n      {\"term_id\": \"GO:0005794\", \"supporting_discovery_ids\": [11]},\n      {\"term_id\": \"GO:0005634\", \"supporting_discovery_ids\": [12]}\n    ],\n    \"pathway\": [\n      {\"term_id\": \"R-HSA-162582\", \"supporting_discovery_ids\": [0, 4, 14]},\n      {\"term_id\": \"R-HSA-1266738\", \"supporting_discovery_ids\": [0, 14]},\n      {\"term_id\": \"R-HSA-1643685\", \"supporting_discovery_ids\": [8, 9, 20]},\n      {\"term_id\": \"R-HSA-9609507\", \"supporting_discovery_ids\": [6, 11]}\n    ],\n    \"complexes\": [\n      \"Evc/Evc2 complex\",\n      \"Fused–Costal2 complex\"\n    ],\n    \"partners\": [\n      \"PTCH1\",\n      \"PTCH2\",\n      \"EVC2\",\n      \"TMED2\",\n      \"ARL13B\",\n      \"HERC4\",\n      \"LATS1\",\n      \"IGF1R\"\n    ],\n    \"other_free_text\": []\n  }\n}","audit_flag":null,"evaluation":{"pairwise":"win","faith_supported":7,"faith_total":7,"faith_pct":100.0}}