{"gene":"TG_245490","gene_symbol":"MIC8","run_date":"2026-09-08T12:58:25","timeline":{"discoveries":[{"year":2002,"finding":"TgMIC8 is a type I transmembrane microneme protein with EGF-like domains, a transmembrane domain, and a short cytoplasmic tail; sorting signals to the micronemes are encoded in the cytoplasmic tail. TgMIC8 acts as an escorter for the soluble adhesin TgMIC3, demonstrating that microneme protein complexes are a general rule rather than exception.","method":"Biochemical characterization, topology assays, pulse-chase/processing analysis, co-immunoprecipitation/complex formation studies","journal":"Journal of cell science","confidence":"High","confidence_rationale":"Tier 2 / Strong — multiple orthogonal methods (topology assay, processing analysis, escorter function demonstrated biochemically), replicated across multiple family members in the same study","pmids":["11861763"],"is_preprint":false,"attribution":[{"species":"Toxoplasma gondii","strain":""}]},{"year":2002,"finding":"TgMIC8 (like TgMIC2 and TgMIC6) is proteolytically cleaved near its C-terminal domain upon discharge from micronemes, consistent with shedding during invasion.","method":"Biochemical processing analysis (pulse-chase, western blot)","journal":"Journal of cell science","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — direct biochemical demonstration in the same study characterizing the family, single lab","pmids":["11861763"],"is_preprint":false,"attribution":[{"species":"Toxoplasma gondii","strain":""}]},{"year":2002,"finding":"The MIC3 dimerization domain (C-terminal end of MIC3) can convert MIC8 — a monomeric micronemal protein sharing MIC3's lectin-like domain — into a dimer capable of interacting with host cell receptors, establishing that dimerization enables receptor binding.","method":"Mammalian cell transfection with truncated/chimeric MIC3-MIC8 constructs, MIC3-binding assay","journal":"The EMBO journal","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — direct functional assay with chimeric constructs in a single lab demonstrating domain-specific dimerization","pmids":["12032066"],"is_preprint":false,"attribution":[{"species":"Toxoplasma gondii","strain":""}]},{"year":2008,"finding":"MIC8 is essential for host cell invasion; conditional knockdown of MIC8 causes a block in invasion specifically at the stage of moving junction formation with the host cell. The cytosolic domain of MIC8 is crucial for this function and cannot be functionally complemented by any other characterized micronemal protein.","method":"Conditional knockdown (regulatable expression system), invasion assays, moving junction formation assays, complementation experiments with chimeric constructs","journal":"Journal of cell science","confidence":"High","confidence_rationale":"Tier 2 / Strong — clean loss-of-function with specific phenotypic readout (moving junction defect), domain-swap complementation experiments, multiple orthogonal assays","pmids":["18319299"],"is_preprint":false,"attribution":[{"species":"Toxoplasma gondii","strain":"RH"}]},{"year":2010,"finding":"TgMIC8 can bind aldolase (connecting adhesive complexes to the actomyosin system) and is a substrate for rhomboid protease cleavage. However, TgMIC8 lacks targeting information within its C-terminal cytoplasmic domain, indicating trafficking to micronemes depends on yet-unidentified proteins interacting with its ectodomain.","method":"Aldolase-binding assays, rhomboid cleavage susceptibility assays, trafficking signal analysis with truncation/chimeric constructs","journal":"Molecular microbiology","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — direct biochemical assays for aldolase binding and rhomboid cleavage, single lab, multiple methods","pmids":["20545864"],"is_preprint":false,"attribution":[{"species":"Toxoplasma gondii","strain":""}]},{"year":2011,"finding":"MIC8 is required for invasion-dependent induction of SOCS1 in macrophages and for escape from IFN-γ-mediated nitric oxide production; Mic8-deficient parasites fail to induce SOCS1 and fail to suppress nitric oxide secretion, establishing that active cell invasion via MIC8 triggers p38 MAP kinase/Egr2 signaling leading to SOCS1 expression.","method":"Mic8-conditional knockdown parasites, SOCS1 induction assays, nitric oxide production assays, pharmacological inhibition of p38 MAP kinase, Egr inhibition","journal":"Immunobiology","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — loss-of-function with specific immunological readout, pathway placement via pharmacological inhibition, single lab","pmids":["22015046"],"is_preprint":false,"attribution":[{"species":"Toxoplasma gondii","strain":"RH"}]},{"year":2016,"finding":"MIC8 secretion is calcium-dependent and MIC8 mediates invasion by interacting with soluble MIC3. Nucleotide sequence analysis of 16 strains confirmed MIC8 is conserved (2055 bp, A+T ~50%), with low sequence variation across genotypes.","method":"Gene sequencing, phylogenetic analysis across multiple T. gondii strains","journal":"Genetics and molecular research : GMR","confidence":"Low","confidence_rationale":"Tier 4 / Weak — primarily sequence/phylogenetic analysis; calcium-dependence and MIC3 interaction are stated as background facts, not newly demonstrated experiments in this paper","pmids":["27173337"],"is_preprint":false,"attribution":[{"species":"Toxoplasma gondii","strain":""}]},{"year":2017,"finding":"In monensin-resistant T. gondii, MIC8 protein is significantly downregulated relative to sensitive parasites, correlating with reduced invasion activity; this proteomic finding implicates MIC8 abundance as a determinant of invasion efficiency.","method":"SILAC-based quantitative proteomics (LC-MS/MS), comparison of resistant vs sensitive strains","journal":"Parasitology","confidence":"Low","confidence_rationale":"Tier 3 / Weak — proteomic correlation in a single lab without direct functional follow-up of MIC8 specifically","pmids":["28870270"],"is_preprint":false,"attribution":[{"species":"Toxoplasma gondii","strain":"RH"}]}],"current_model":"TgMIC8 is a type I transmembrane microneme protein with EGF-like ectodomains and a functionally essential cytosolic tail; it acts as an escorter for soluble MIC3, undergoes rhomboid-mediated shedding upon microneme discharge, can bind aldolase, and is specifically required for moving junction formation during host cell invasion — a function uniquely dependent on its cytosolic domain — and additionally enables invasion-coupled SOCS1 induction in host macrophages via the p38/Egr2 pathway."},"narrative":{"mechanistic_narrative":"TgMIC8 is a type I transmembrane microneme protein of Toxoplasma gondii that couples adhesin trafficking to the invasion machinery and is specifically required for host cell entry [PMID:11861763, PMID:18319299]. Its ectodomain contains EGF-like and lectin-like domains, and it functions as an escorter for the soluble adhesin MIC3, establishing that microneme proteins operate as complexes [PMID:11861763]; when fused with the MIC3 dimerization domain, MIC8's monomeric lectin-like domain can be converted into a dimer capable of host receptor binding [PMID:12032066]. Conditional knockdown shows MIC8 is essential for invasion, blocking specifically at moving junction formation, a role that depends critically and non-redundantly on its cytosolic tail [PMID:18319299]. MIC8 binds aldolase, linking adhesive complexes to the actomyosin system, and is a substrate for rhomboid-mediated shedding upon microneme discharge [PMID:11861763, PMID:20545864]. Beyond its role in entry, invasion driven by MIC8 triggers p38 MAP kinase/Egr2 signaling in host macrophages, inducing SOCS1 and enabling escape from IFN-γ-mediated nitric oxide production [PMID:22015046].","teleology":[{"year":2002,"claim":"Established that MIC8 is a transmembrane microneme protein that chaperones a soluble adhesin, answering how the soluble adhesin MIC3 reaches and is anchored at the micronemes and defining microneme complexes as a general organizing principle.","evidence":"Topology assays, processing analysis, and co-immunoprecipitation demonstrating escorter function for MIC3","pmids":["11861763"],"confidence":"High","gaps":["Did not resolve whether the cytosolic tail alone dictates microneme sorting","Direct functional role in invasion not yet tested"],"attribution":[{"species":"Toxoplasma gondii","strain":""}]},{"year":2002,"claim":"Showed MIC8 is proteolytically cleaved near its C-terminus upon discharge, indicating it is shed during the invasion process like other microneme adhesins.","evidence":"Pulse-chase and western blot processing analysis of the MIC family","pmids":["11861763"],"confidence":"Medium","gaps":["Protease responsible not identified in this study","Functional consequence of shedding untested"],"attribution":[{"species":"Toxoplasma gondii","strain":""}]},{"year":2002,"claim":"Defined the molecular basis of receptor engagement by showing that the MIC3 dimerization domain confers host receptor binding on otherwise monomeric MIC8, establishing dimerization as the switch enabling adhesion.","evidence":"Mammalian cell transfection with chimeric MIC3-MIC8 constructs and receptor-binding assays","pmids":["12032066"],"confidence":"Medium","gaps":["Native MIC8 dimerization state in the parasite not directly established","Host receptor identity not defined"],"attribution":[{"species":"Toxoplasma gondii","strain":""}]},{"year":2008,"claim":"Demonstrated MIC8 is essential for invasion with a specific, non-redundant defect at moving junction formation, and localized this function to its cytosolic domain, distinguishing MIC8 from other microneme proteins.","evidence":"Conditional knockdown, invasion and moving junction assays, and domain-swap complementation in RH strain","pmids":["18319299"],"confidence":"High","gaps":["The cytosolic tail's downstream effectors driving junction formation not identified","How MIC8 signals to the junction machinery unknown"],"attribution":[{"species":"Toxoplasma gondii","strain":"RH"}]},{"year":2010,"claim":"Connected MIC8 to the invasion motor and to shedding by showing it binds aldolase and is a rhomboid substrate, while revealing that microneme targeting does not reside in its cytoplasmic tail but depends on ectodomain partners.","evidence":"Aldolase-binding and rhomboid cleavage assays, plus trafficking-signal mapping with truncation/chimeric constructs","pmids":["20545864"],"confidence":"Medium","gaps":["The ectodomain-interacting trafficking partner remains unidentified","Aldolase binding not directly linked to the moving junction defect"],"attribution":[{"species":"Toxoplasma gondii","strain":""}]},{"year":2011,"claim":"Extended MIC8 function beyond entry by showing invasion via MIC8 activates host p38/Egr2 signaling to induce SOCS1, enabling the parasite to subvert IFN-γ-driven nitric oxide defenses.","evidence":"Mic8-conditional knockdown parasites with SOCS1 and nitric oxide assays and pharmacological p38/Egr inhibition in RH strain","pmids":["22015046"],"confidence":"Medium","gaps":["Whether MIC8 acts directly or via the invasion event per se not separated","Host receptor triggering p38 signaling not identified"],"attribution":[{"species":"Toxoplasma gondii","strain":"RH"}]},{"year":2016,"claim":"Confirmed MIC8 is broadly conserved with low variation across genotypes and reaffirmed calcium-dependent secretion and MIC3 interaction as core features.","evidence":"Gene sequencing and phylogenetic analysis across 16 strains","pmids":["27173337"],"confidence":"Low","gaps":["Calcium-dependence and MIC3 binding cited as background, not newly demonstrated here","Functional consequence of sequence variation untested"],"attribution":[{"species":"Toxoplasma gondii","strain":""}]},{"year":2017,"claim":"Correlated MIC8 protein abundance with invasion efficiency by finding it downregulated in monensin-resistant, poorly invasive parasites.","evidence":"SILAC quantitative proteomics comparing resistant and sensitive RH parasites","pmids":["28870270"],"confidence":"Low","gaps":["Correlative only; no direct functional manipulation of MIC8 in this context","Mechanism linking monensin resistance to MIC8 loss unknown"],"attribution":[{"species":"Toxoplasma gondii","strain":"RH"}]},{"year":null,"claim":"The identity of the ectodomain-interacting protein that targets MIC8 to micronemes, and the molecular effectors through which its cytosolic tail drives moving junction formation, remain unresolved.","evidence":"","pmids":[],"confidence":"Medium","gaps":["Microneme-targeting partner unidentified","Cytosolic tail effectors at the junction undefined","Host receptor(s) engaged during invasion and p38 activation unknown"],"attribution":[{"species":"Toxoplasma gondii","strain":""}]}],"mechanism_profile":{"molecular_activity":[],"localization":[],"pathway":[],"complexes":["MIC8-MIC3 escorter complex"],"partners":["MIC3","ALDOLASE","RHOMBOID PROTEASE"],"other_free_text":["Type I transmembrane microneme protein with EGF-like and lectin-like ectodomains and a short, functionally essential cytosolic tail [#0, #3]","Cytosolic tail is uniquely required for moving junction formation and cannot be complemented by other microneme proteins [#3]","Microneme targeting depends on ectodomain-interacting partners rather than the cytoplasmic tail [#4]","Invasion via MIC8 induces host macrophage SOCS1 through p38 MAP kinase/Egr2 signaling, suppressing IFN-γ-driven nitric oxide production [#5]"]},"strain_conflicts":[]},"prefetch_data":{},"corpus_meta":[{"pmid":"11861763","id":"PMC_11861763","title":"A family of transmembrane microneme proteins of Toxoplasma gondii contain EGF-like domains and function as escorters.","date":"2002","source":"Journal of cell science","url":"https://pubmed.ncbi.nlm.nih.gov/11861763","citation_count":135,"is_preprint":false},{"pmid":"18319299","id":"PMC_18319299","title":"Microneme protein 8--a new essential invasion factor in Toxoplasma gondii.","date":"2008","source":"Journal of cell science","url":"https://pubmed.ncbi.nlm.nih.gov/18319299","citation_count":110,"is_preprint":false},{"pmid":"12032066","id":"PMC_12032066","title":"The Toxoplasma gondii protein MIC3 requires pro-peptide cleavage and dimerization to function as adhesin.","date":"2002","source":"The EMBO journal","url":"https://pubmed.ncbi.nlm.nih.gov/12032066","citation_count":63,"is_preprint":false},{"pmid":"20545864","id":"PMC_20545864","title":"Toxoplasma gondii transmembrane microneme proteins and their modular design.","date":"2010","source":"Molecular microbiology","url":"https://pubmed.ncbi.nlm.nih.gov/20545864","citation_count":60,"is_preprint":false},{"pmid":"20177910","id":"PMC_20177910","title":"Toxoplasma gondii microneme protein 8 (MIC8) is a potential vaccine candidate against toxoplasmosis.","date":"2010","source":"Parasitology research","url":"https://pubmed.ncbi.nlm.nih.gov/20177910","citation_count":51,"is_preprint":false},{"pmid":"24690150","id":"PMC_24690150","title":"Synergy of mIL-21 and mIL-15 in enhancing DNA vaccine efficacy against acute and chronic Toxoplasma gondii infection in mice.","date":"2014","source":"Vaccine","url":"https://pubmed.ncbi.nlm.nih.gov/24690150","citation_count":47,"is_preprint":false},{"pmid":"30107996","id":"PMC_30107996","title":"Virus-like particle vaccines expressing Toxoplasma gondii rhoptry protein 18 and microneme protein 8 provide enhanced protection.","date":"2018","source":"Vaccine","url":"https://pubmed.ncbi.nlm.nih.gov/30107996","citation_count":36,"is_preprint":false},{"pmid":"28406951","id":"PMC_28406951","title":"Protection induced by virus-like particles containing Toxoplasma gondii microneme protein 8 against highly virulent RH strain of Toxoplasma gondii infection.","date":"2017","source":"PloS one","url":"https://pubmed.ncbi.nlm.nih.gov/28406951","citation_count":32,"is_preprint":false},{"pmid":"22015046","id":"PMC_22015046","title":"Cell invasion and strain dependent induction of suppressor of cytokine signaling-1 by Toxoplasma gondii.","date":"2011","source":"Immunobiology","url":"https://pubmed.ncbi.nlm.nih.gov/22015046","citation_count":30,"is_preprint":false},{"pmid":"30666253","id":"PMC_30666253","title":"Protective Immunity Induced by Incorporating Multiple Antigenic Proteins of Toxoplasma gondii Into Influenza Virus-Like Particles.","date":"2019","source":"Frontiers in immunology","url":"https://pubmed.ncbi.nlm.nih.gov/30666253","citation_count":24,"is_preprint":false},{"pmid":"31465461","id":"PMC_31465461","title":"Virus-like particles containing multiple antigenic proteins of Toxoplasma gondii induce memory T cell and B cell responses.","date":"2019","source":"PloS one","url":"https://pubmed.ncbi.nlm.nih.gov/31465461","citation_count":14,"is_preprint":false},{"pmid":"33242641","id":"PMC_33242641","title":"Engineering an efficient poly-epitope vaccine against Toxoplasma gondii infection: A computational vaccinology study.","date":"2020","source":"Microbial pathogenesis","url":"https://pubmed.ncbi.nlm.nih.gov/33242641","citation_count":10,"is_preprint":false},{"pmid":"28870270","id":"PMC_28870270","title":"Resistance towards monensin is proposed to be acquired in a Toxoplasma gondii model by reduced invasion and egress activities, in addition to increased intracellular replication.","date":"2017","source":"Parasitology","url":"https://pubmed.ncbi.nlm.nih.gov/28870270","citation_count":10,"is_preprint":false},{"pmid":"39694399","id":"PMC_39694399","title":"Protective humoral immunity induced by virus-like particles expressing Toxoplasma gondii CST1 or MIC8.","date":"2024","source":"Acta tropica","url":"https://pubmed.ncbi.nlm.nih.gov/39694399","citation_count":6,"is_preprint":false},{"pmid":"33922808","id":"PMC_33922808","title":"Passive Immunity and Antibody Response Induced by Toxoplasma gondii VLP Immunization.","date":"2021","source":"Vaccines","url":"https://pubmed.ncbi.nlm.nih.gov/33922808","citation_count":6,"is_preprint":false},{"pmid":"24812879","id":"PMC_24812879","title":"Evaluation on the immune response induced by DNA vaccine encoding MIC8 co-immunized with IL-12 genetic adjuvant against Toxoplasma gondii infection.","date":"2013","source":"Zhongguo ji sheng chong xue yu ji sheng chong bing za zhi = Chinese journal of parasitology & parasitic diseases","url":"https://pubmed.ncbi.nlm.nih.gov/24812879","citation_count":5,"is_preprint":false},{"pmid":"41311041","id":"PMC_41311041","title":"Vaccinia virus expressing MIC8 and AMA1 provides protection against Toxoplasma gondii ME49 infection.","date":"2025","source":"Parasites, hosts and diseases","url":"https://pubmed.ncbi.nlm.nih.gov/41311041","citation_count":3,"is_preprint":false},{"pmid":"40886931","id":"PMC_40886931","title":"Recombinant vaccinia virus expressing MIC8, AMA1, or RON4 induce protection against Toxoplasma gondii ME49 strain infection.","date":"2025","source":"Acta tropica","url":"https://pubmed.ncbi.nlm.nih.gov/40886931","citation_count":3,"is_preprint":false},{"pmid":"20666305","id":"PMC_20666305","title":"Protective immunity induced in mice by multiantigenic DNA vaccine with genes encoding SAG1 and MIC8 of Toxoplasma gondii.","date":"2010","source":"Zhongguo ji sheng chong xue yu ji sheng chong bing za zhi = Chinese journal of parasitology & parasitic diseases","url":"https://pubmed.ncbi.nlm.nih.gov/20666305","citation_count":2,"is_preprint":false},{"pmid":"40872947","id":"PMC_40872947","title":"Efficacy of Heterologous Vaccination Using Virus-Like Particles and Vaccinia Virus Containing MIC8 and AMA1 Proteins of Toxoplasma gondii.","date":"2025","source":"Vaccines","url":"https://pubmed.ncbi.nlm.nih.gov/40872947","citation_count":2,"is_preprint":false},{"pmid":"41955927","id":"PMC_41955927","title":"Heterologous DNA prime-crude tachyzoite lysate antigen boost targeting MIC8 confers protection against acute and chronic Toxoplasma gondii infection in mice.","date":"2026","source":"Vaccine","url":"https://pubmed.ncbi.nlm.nih.gov/41955927","citation_count":0,"is_preprint":false},{"pmid":"27173337","id":"PMC_27173337","title":"Nucleotide variation in the Toxoplasma gondii micronemal protein 8 gene.","date":"2016","source":"Genetics and molecular research : GMR","url":"https://pubmed.ncbi.nlm.nih.gov/27173337","citation_count":0,"is_preprint":false},{"pmid":"42070374","id":"PMC_42070374","title":"Corrigendum to \"Heterologous DNA prime-crude tachyzoite lysate antigen boost targeting MIC8 confers protection against acute and chronic Toxoplasma gondii infection in mice\" [Vaccine 80 (2026) 128554].","date":"2026","source":"Vaccine","url":"https://pubmed.ncbi.nlm.nih.gov/42070374","citation_count":0,"is_preprint":false}],"cost":{"stage1":{"model":"claude-sonnet-4-6","input_tokens":13698,"output_tokens":2058,"usd":0.035982,"stage1_stop_reason":"end_turn"},"stage2":{"model":"claude-opus-4-8","input_tokens":7504,"output_tokens":3366,"usd":0.060835,"stage2_stop_reason":"end_turn"},"total_usd":0.096817,"stage1_batch_id":"msgbatch_01TEPNZ4MCzJ7xtsNwosiDRk","stage2_batch_id":"msgbatch_01FQShM7n1sfCr4pWTDShmki","note":"batch pricing = 50% of standard"},"stage1_raw":"```json\n{\n  \"discoveries\": [\n    {\n      \"year\": 2002,\n      \"finding\": \"TgMIC8 is a type I transmembrane microneme protein with EGF-like domains, a transmembrane domain, and a short cytoplasmic tail; sorting signals to the micronemes are encoded in the cytoplasmic tail. TgMIC8 acts as an escorter for the soluble adhesin TgMIC3, demonstrating that microneme protein complexes are a general rule rather than exception.\",\n      \"method\": \"Biochemical characterization, topology assays, pulse-chase/processing analysis, co-immunoprecipitation/complex formation studies\",\n      \"journal\": \"Journal of cell science\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — multiple orthogonal methods (topology assay, processing analysis, escorter function demonstrated biochemically), replicated across multiple family members in the same study\",\n      \"pmids\": [\"11861763\"],\n      \"is_preprint\": false,\n      \"attribution\": [{\"species\": \"Toxoplasma gondii\", \"strain\": \"\"}]\n    },\n    {\n      \"year\": 2002,\n      \"finding\": \"TgMIC8 (like TgMIC2 and TgMIC6) is proteolytically cleaved near its C-terminal domain upon discharge from micronemes, consistent with shedding during invasion.\",\n      \"method\": \"Biochemical processing analysis (pulse-chase, western blot)\",\n      \"journal\": \"Journal of cell science\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — direct biochemical demonstration in the same study characterizing the family, single lab\",\n      \"pmids\": [\"11861763\"],\n      \"is_preprint\": false,\n      \"attribution\": [{\"species\": \"Toxoplasma gondii\", \"strain\": \"\"}]\n    },\n    {\n      \"year\": 2002,\n      \"finding\": \"The MIC3 dimerization domain (C-terminal end of MIC3) can convert MIC8 — a monomeric micronemal protein sharing MIC3's lectin-like domain — into a dimer capable of interacting with host cell receptors, establishing that dimerization enables receptor binding.\",\n      \"method\": \"Mammalian cell transfection with truncated/chimeric MIC3-MIC8 constructs, MIC3-binding assay\",\n      \"journal\": \"The EMBO journal\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — direct functional assay with chimeric constructs in a single lab demonstrating domain-specific dimerization\",\n      \"pmids\": [\"12032066\"],\n      \"is_preprint\": false,\n      \"attribution\": [{\"species\": \"Toxoplasma gondii\", \"strain\": \"\"}]\n    },\n    {\n      \"year\": 2008,\n      \"finding\": \"MIC8 is essential for host cell invasion; conditional knockdown of MIC8 causes a block in invasion specifically at the stage of moving junction formation with the host cell. The cytosolic domain of MIC8 is crucial for this function and cannot be functionally complemented by any other characterized micronemal protein.\",\n      \"method\": \"Conditional knockdown (regulatable expression system), invasion assays, moving junction formation assays, complementation experiments with chimeric constructs\",\n      \"journal\": \"Journal of cell science\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — clean loss-of-function with specific phenotypic readout (moving junction defect), domain-swap complementation experiments, multiple orthogonal assays\",\n      \"pmids\": [\"18319299\"],\n      \"is_preprint\": false,\n      \"attribution\": [{\"species\": \"Toxoplasma gondii\", \"strain\": \"RH\"}]\n    },\n    {\n      \"year\": 2010,\n      \"finding\": \"TgMIC8 can bind aldolase (connecting adhesive complexes to the actomyosin system) and is a substrate for rhomboid protease cleavage. However, TgMIC8 lacks targeting information within its C-terminal cytoplasmic domain, indicating trafficking to micronemes depends on yet-unidentified proteins interacting with its ectodomain.\",\n      \"method\": \"Aldolase-binding assays, rhomboid cleavage susceptibility assays, trafficking signal analysis with truncation/chimeric constructs\",\n      \"journal\": \"Molecular microbiology\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — direct biochemical assays for aldolase binding and rhomboid cleavage, single lab, multiple methods\",\n      \"pmids\": [\"20545864\"],\n      \"is_preprint\": false,\n      \"attribution\": [{\"species\": \"Toxoplasma gondii\", \"strain\": \"\"}]\n    },\n    {\n      \"year\": 2011,\n      \"finding\": \"MIC8 is required for invasion-dependent induction of SOCS1 in macrophages and for escape from IFN-γ-mediated nitric oxide production; Mic8-deficient parasites fail to induce SOCS1 and fail to suppress nitric oxide secretion, establishing that active cell invasion via MIC8 triggers p38 MAP kinase/Egr2 signaling leading to SOCS1 expression.\",\n      \"method\": \"Mic8-conditional knockdown parasites, SOCS1 induction assays, nitric oxide production assays, pharmacological inhibition of p38 MAP kinase, Egr inhibition\",\n      \"journal\": \"Immunobiology\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — loss-of-function with specific immunological readout, pathway placement via pharmacological inhibition, single lab\",\n      \"pmids\": [\"22015046\"],\n      \"is_preprint\": false,\n      \"attribution\": [{\"species\": \"Toxoplasma gondii\", \"strain\": \"RH\"}]\n    },\n    {\n      \"year\": 2016,\n      \"finding\": \"MIC8 secretion is calcium-dependent and MIC8 mediates invasion by interacting with soluble MIC3. Nucleotide sequence analysis of 16 strains confirmed MIC8 is conserved (2055 bp, A+T ~50%), with low sequence variation across genotypes.\",\n      \"method\": \"Gene sequencing, phylogenetic analysis across multiple T. gondii strains\",\n      \"journal\": \"Genetics and molecular research : GMR\",\n      \"confidence\": \"Low\",\n      \"confidence_rationale\": \"Tier 4 / Weak — primarily sequence/phylogenetic analysis; calcium-dependence and MIC3 interaction are stated as background facts, not newly demonstrated experiments in this paper\",\n      \"pmids\": [\"27173337\"],\n      \"is_preprint\": false,\n      \"attribution\": [{\"species\": \"Toxoplasma gondii\", \"strain\": \"\"}]\n    },\n    {\n      \"year\": 2017,\n      \"finding\": \"In monensin-resistant T. gondii, MIC8 protein is significantly downregulated relative to sensitive parasites, correlating with reduced invasion activity; this proteomic finding implicates MIC8 abundance as a determinant of invasion efficiency.\",\n      \"method\": \"SILAC-based quantitative proteomics (LC-MS/MS), comparison of resistant vs sensitive strains\",\n      \"journal\": \"Parasitology\",\n      \"confidence\": \"Low\",\n      \"confidence_rationale\": \"Tier 3 / Weak — proteomic correlation in a single lab without direct functional follow-up of MIC8 specifically\",\n      \"pmids\": [\"28870270\"],\n      \"is_preprint\": false,\n      \"attribution\": [{\"species\": \"Toxoplasma gondii\", \"strain\": \"RH\"}]\n    }\n  ],\n  \"current_model\": \"TgMIC8 is a type I transmembrane microneme protein with EGF-like ectodomains and a functionally essential cytosolic tail; it acts as an escorter for soluble MIC3, undergoes rhomboid-mediated shedding upon microneme discharge, can bind aldolase, and is specifically required for moving junction formation during host cell invasion — a function uniquely dependent on its cytosolic domain — and additionally enables invasion-coupled SOCS1 induction in host macrophages via the p38/Egr2 pathway.\"\n}\n```","stage2_raw":"```json\n{\n  \"mechanistic_narrative\": \"TgMIC8 is a type I transmembrane microneme protein of Toxoplasma gondii that couples adhesin trafficking to the invasion machinery and is specifically required for host cell entry [#0, #3]. Its ectodomain contains EGF-like and lectin-like domains, and it functions as an escorter for the soluble adhesin MIC3, establishing that microneme proteins operate as complexes [#0]; when fused with the MIC3 dimerization domain, MIC8's monomeric lectin-like domain can be converted into a dimer capable of host receptor binding [#2]. Conditional knockdown shows MIC8 is essential for invasion, blocking specifically at moving junction formation, a role that depends critically and non-redundantly on its cytosolic tail [#3]. MIC8 binds aldolase, linking adhesive complexes to the actomyosin system, and is a substrate for rhomboid-mediated shedding upon microneme discharge [#1, #4]. Beyond its role in entry, invasion driven by MIC8 triggers p38 MAP kinase/Egr2 signaling in host macrophages, inducing SOCS1 and enabling escape from IFN-\\u03b3-mediated nitric oxide production [#5].\",\n  \"teleology\": [\n    {\n      \"year\": 2002,\n      \"claim\": \"Established that MIC8 is a transmembrane microneme protein that chaperones a soluble adhesin, answering how the soluble adhesin MIC3 reaches and is anchored at the micronemes and defining microneme complexes as a general organizing principle.\",\n      \"evidence\": \"Topology assays, processing analysis, and co-immunoprecipitation demonstrating escorter function for MIC3\",\n      \"pmids\": [\"11861763\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Did not resolve whether the cytosolic tail alone dictates microneme sorting\", \"Direct functional role in invasion not yet tested\"],\n      \"attribution\": [{\"species\": \"Toxoplasma gondii\", \"strain\": \"\"}]\n    },\n    {\n      \"year\": 2002,\n      \"claim\": \"Showed MIC8 is proteolytically cleaved near its C-terminus upon discharge, indicating it is shed during the invasion process like other microneme adhesins.\",\n      \"evidence\": \"Pulse-chase and western blot processing analysis of the MIC family\",\n      \"pmids\": [\"11861763\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Protease responsible not identified in this study\", \"Functional consequence of shedding untested\"],\n      \"attribution\": [{\"species\": \"Toxoplasma gondii\", \"strain\": \"\"}]\n    },\n    {\n      \"year\": 2002,\n      \"claim\": \"Defined the molecular basis of receptor engagement by showing that the MIC3 dimerization domain confers host receptor binding on otherwise monomeric MIC8, establishing dimerization as the switch enabling adhesion.\",\n      \"evidence\": \"Mammalian cell transfection with chimeric MIC3-MIC8 constructs and receptor-binding assays\",\n      \"pmids\": [\"12032066\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Native MIC8 dimerization state in the parasite not directly established\", \"Host receptor identity not defined\"],\n      \"attribution\": [{\"species\": \"Toxoplasma gondii\", \"strain\": \"\"}]\n    },\n    {\n      \"year\": 2008,\n      \"claim\": \"Demonstrated MIC8 is essential for invasion with a specific, non-redundant defect at moving junction formation, and localized this function to its cytosolic domain, distinguishing MIC8 from other microneme proteins.\",\n      \"evidence\": \"Conditional knockdown, invasion and moving junction assays, and domain-swap complementation in RH strain\",\n      \"pmids\": [\"18319299\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"The cytosolic tail's downstream effectors driving junction formation not identified\", \"How MIC8 signals to the junction machinery unknown\"],\n      \"attribution\": [{\"species\": \"Toxoplasma gondii\", \"strain\": \"RH\"}]\n    },\n    {\n      \"year\": 2010,\n      \"claim\": \"Connected MIC8 to the invasion motor and to shedding by showing it binds aldolase and is a rhomboid substrate, while revealing that microneme targeting does not reside in its cytoplasmic tail but depends on ectodomain partners.\",\n      \"evidence\": \"Aldolase-binding and rhomboid cleavage assays, plus trafficking-signal mapping with truncation/chimeric constructs\",\n      \"pmids\": [\"20545864\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"The ectodomain-interacting trafficking partner remains unidentified\", \"Aldolase binding not directly linked to the moving junction defect\"],\n      \"attribution\": [{\"species\": \"Toxoplasma gondii\", \"strain\": \"\"}]\n    },\n    {\n      \"year\": 2011,\n      \"claim\": \"Extended MIC8 function beyond entry by showing invasion via MIC8 activates host p38/Egr2 signaling to induce SOCS1, enabling the parasite to subvert IFN-\\u03b3-driven nitric oxide defenses.\",\n      \"evidence\": \"Mic8-conditional knockdown parasites with SOCS1 and nitric oxide assays and pharmacological p38/Egr inhibition in RH strain\",\n      \"pmids\": [\"22015046\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Whether MIC8 acts directly or via the invasion event per se not separated\", \"Host receptor triggering p38 signaling not identified\"],\n      \"attribution\": [{\"species\": \"Toxoplasma gondii\", \"strain\": \"RH\"}]\n    },\n    {\n      \"year\": 2016,\n      \"claim\": \"Confirmed MIC8 is broadly conserved with low variation across genotypes and reaffirmed calcium-dependent secretion and MIC3 interaction as core features.\",\n      \"evidence\": \"Gene sequencing and phylogenetic analysis across 16 strains\",\n      \"pmids\": [\"27173337\"],\n      \"confidence\": \"Low\",\n      \"gaps\": [\"Calcium-dependence and MIC3 binding cited as background, not newly demonstrated here\", \"Functional consequence of sequence variation untested\"],\n      \"attribution\": [{\"species\": \"Toxoplasma gondii\", \"strain\": \"\"}]\n    },\n    {\n      \"year\": 2017,\n      \"claim\": \"Correlated MIC8 protein abundance with invasion efficiency by finding it downregulated in monensin-resistant, poorly invasive parasites.\",\n      \"evidence\": \"SILAC quantitative proteomics comparing resistant and sensitive RH parasites\",\n      \"pmids\": [\"28870270\"],\n      \"confidence\": \"Low\",\n      \"gaps\": [\"Correlative only; no direct functional manipulation of MIC8 in this context\", \"Mechanism linking monensin resistance to MIC8 loss unknown\"],\n      \"attribution\": [{\"species\": \"Toxoplasma gondii\", \"strain\": \"RH\"}]\n    },\n    {\n      \"year\": null,\n      \"claim\": \"The identity of the ectodomain-interacting protein that targets MIC8 to micronemes, and the molecular effectors through which its cytosolic tail drives moving junction formation, remain unresolved.\",\n      \"evidence\": \"\",\n      \"pmids\": [],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Microneme-targeting partner unidentified\", \"Cytosolic tail effectors at the junction undefined\", \"Host receptor(s) engaged during invasion and p38 activation unknown\"],\n      \"attribution\": [{\"species\": \"Toxoplasma gondii\", \"strain\": \"\"}]\n    }\n  ],\n  \"mechanism_profile\": {\n    \"molecular_activity\": [\n      {\"term_id\": \"GO:0005198\", \"supporting_discovery_ids\": [0, 3], \"attribution\": [{\"species\": \"Toxoplasma gondii\", \"strain\": \"\"}]},\n      {\"term_id\": \"GO:0005102\", \"supporting_discovery_ids\": [2, 4], \"attribution\": [{\"species\": \"Toxoplasma gondii\", \"strain\": \"\"}]}\n    ],\n    \"localization\": [\n      {\"term_id\": \"GO:0020009\", \"supporting_discovery_ids\": [0], \"attribution\": [{\"species\": \"Toxoplasma gondii\", \"strain\": \"\"}]},\n      {\"term_id\": \"GO:0016020\", \"supporting_discovery_ids\": [0], \"attribution\": [{\"species\": \"Toxoplasma gondii\", \"strain\": \"\"}]}\n    ],\n    \"pathway\": [\n      {\"term_id\": \"GO:0044409\", \"supporting_discovery_ids\": [3], \"attribution\": [{\"species\": \"Toxoplasma gondii\", \"strain\": \"RH\"}]},\n      {\"term_id\": \"GO:0006952\", \"supporting_discovery_ids\": [5], \"attribution\": [{\"species\": \"Toxoplasma gondii\", \"strain\": \"RH\"}]}\n    ],\n    \"complexes\": [\"MIC8-MIC3 escorter complex\"],\n    \"partners\": [\"MIC3\", \"aldolase\", \"rhomboid protease\"],\n    \"other_free_text\": [\n      \"Type I transmembrane microneme protein with EGF-like and lectin-like ectodomains and a short, functionally essential cytosolic tail [#0, #3]\",\n      \"Cytosolic tail is uniquely required for moving junction formation and cannot be complemented by other microneme proteins [#3]\",\n      \"Microneme targeting depends on ectodomain-interacting partners rather than the cytoplasmic tail [#4]\",\n      \"Invasion via MIC8 induces host macrophage SOCS1 through p38 MAP kinase/Egr2 signaling, suppressing IFN-\\u03b3-driven nitric oxide production [#5]\"\n    ]\n  },\n  \"strain_conflicts\": []\n}\n```","audit_flag":null,"strains":[{"strain":"ME49","gene_id":"TGME49_245490","name":"MIC8","product":"microneme protein MIC8","uniprot_acc":"A0A125YRT0","chromosome":"TGME49_chrXII","start_pos":2305996},{"strain":"GT1","gene_id":"TGGT1_245490","name":null,"product":"microneme protein MIC8","uniprot_acc":null,"chromosome":"TGGT1_chrXII","start_pos":2242495},{"strain":"RH88","gene_id":"TGRH88_060120","name":null,"product":"microneme protein MIC8","uniprot_acc":null,"chromosome":"CM023093","start_pos":2333720},{"strain":"VEG","gene_id":"TGVEG_245490","name":null,"product":"microneme protein MIC8","uniprot_acc":"A0A0F7VCB9","chromosome":"TGVEG_chrXII","start_pos":2274298}]}