{"gene":"TG_305340","gene_symbol":"MORC","run_date":"2026-09-08T15:15:12","timeline":{"discoveries":[{"year":2020,"finding":"Toxoplasma gondii MORC forms a complex with AP2 transcription factors and recruits histone deacetylase HDAC3, thereby reducing chromatin accessibility at genes exclusively expressed during sexual stages and functioning as a transcriptional repressor of sexual commitment.","method":"Co-immunoprecipitation, chromatin accessibility assays, conditional depletion (auxin-inducible degron), transcriptomic analysis","journal":"Nature microbiology","confidence":"High","confidence_rationale":"Tier 2 / Strong — reciprocal Co-IP establishing complex, chromatin accessibility assays, conditional KD with defined transcriptional phenotype, replicated across multiple subsequent studies","pmids":["32094587"],"is_preprint":false,"attribution":[{"species":"Toxoplasma gondii","strain":""}]},{"year":2020,"finding":"MORC acts as a master regulator that directs hierarchical expression of secondary AP2 transcription factors, controlling the unidirectionality of the tachyzoite-to-sexual stage transition; conditional MORC depletion causes a shift from asexual proliferation to sexual differentiation.","method":"Conditional protein depletion, RNA-seq transcriptomics, chromatin immunoprecipitation","journal":"Nature microbiology","confidence":"High","confidence_rationale":"Tier 2 / Strong — conditional KD with defined transcriptional and developmental phenotype, multiple orthogonal methods, replicated in subsequent studies","pmids":["32094587"],"is_preprint":false,"attribution":[{"species":"Toxoplasma gondii","strain":""}]},{"year":2020,"finding":"AP2IX-4 is a component of the MORC transcriptional repressor complex, identified by purification of AP2IX-4-interacting proteins.","method":"Co-immunoprecipitation and mass spectrometry (affinity purification-MS)","journal":"mSphere","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — affinity purification-MS identifying complex membership, single lab","pmids":["32938695"],"is_preprint":false,"attribution":[{"species":"Toxoplasma gondii","strain":""}]},{"year":2023,"finding":"AP2XII-2 associates at genomic loci with HDAC3 and MORC and is required for silencing of a subset of sexual stage genes including AP2X-10 and AAH1, as shown by CUT&Tag mapping and conditional depletion.","method":"CUT&Tag (cleavage under targets and tagmentation), conditional depletion, transcriptomic analysis","journal":"mSphere","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — CUT&Tag genome-wide binding mapped with conditional KD phenotype, single lab, two orthogonal methods","pmids":["36786611"],"is_preprint":false,"attribution":[{"species":"Toxoplasma gondii","strain":""}]},{"year":2023,"finding":"AP2XII-1 and AP2XI-2 bind DNA as heterodimers at merozoite promoters in tachyzoites and recruit MORC and HDAC3 to restrict chromatin accessibility and silence merozoite genes; simultaneous depletion of these factors causes full tachyzoite-to-merozoite transition.","method":"Chromatin immunoprecipitation, chromatin accessibility assays (ATAC-seq), conditional co-depletion, transcriptomics, mass spectrometry","journal":"Nature","confidence":"High","confidence_rationale":"Tier 2 / Strong — reciprocal Co-IP, ATAC-seq, conditional co-KD with defined developmental phenotype, multiple orthogonal methods, published in peer-reviewed journal","pmids":["38093015"],"is_preprint":false,"attribution":[{"species":"Toxoplasma gondii","strain":""}]},{"year":2023,"finding":"AP2XII-1 and AP2XI-2 recruit MORC and HDAC3 to merozoite promoters to restrict chromatin accessibility (preprint version of the Nature 2023 paper).","method":"ChIP, ATAC-seq, conditional co-depletion, mass spectrometry","journal":"bioRxiv","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — preprint superseded by peer-reviewed publication (PMID:38093015); included as corroborating evidence","pmids":["36711883"],"is_preprint":true,"attribution":[{"species":"Toxoplasma gondii","strain":""}]},{"year":2024,"finding":"AP2XII-5 forms a nuclear complex with MORC, HDAC3, and a novel stabilizing protein AIP1; AP2XII-5 binds promoters of developmentally activated genes and recruits MORC and HDAC3 to suppress their expression in tachyzoites.","method":"Co-immunoprecipitation, mass spectrometry, chromatin immunoprecipitation, conditional depletion","journal":"Advanced science","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — Co-IP/MS identifying complex, ChIP mapping binding, conditional KD with transcriptional phenotype, single lab","pmids":["39716984"],"is_preprint":false,"attribution":[{"species":"Toxoplasma gondii","strain":""}]},{"year":2024,"finding":"AP2XII-1 and AP2XI-2 conditional knockout causes upregulation of merozoite-specific genes targeted by the MORC-HDAC3 complex, with AP2XII-1 specifically binding to a subset of AP2 transcription factors including AP2XI-2.","method":"Immunoprecipitation, mass spectrometry, conditional knockout, transcriptomics","journal":"International journal of molecular sciences","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — IP-MS and conditional KO with defined transcriptional phenotype, single lab","pmids":["38791568"],"is_preprint":false,"attribution":[{"species":"Toxoplasma gondii","strain":""}]},{"year":2025,"finding":"TgSNF2h (an ISWI chromatin remodeler) exerts epistatic control over MORC by modulating chromatin accessibility to transcription factors, placing TgSNF2h upstream of MORC in the epigenetic regulatory hierarchy for developmental gene regulation.","method":"Genetic epistasis analysis, conditional depletion, ATAC-seq chromatin accessibility, transcriptomics","journal":"Nature microbiology","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — epistasis established by genetic depletion with ATAC-seq readout, single lab","pmids":["40217127"],"is_preprint":false,"attribution":[{"species":"Toxoplasma gondii","strain":""}]},{"year":2025,"finding":"MORC and HDAC3 epistatically regulate BFD1, a key bradyzoite transcriptional regulator, placing MORC upstream of BFD1 in the bradyzoite differentiation pathway.","method":"Genetic epistasis analysis, conditional depletion, transcriptomics","journal":"EMBO molecular medicine","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — epistasis by conditional depletion with transcriptional readout, single lab","pmids":["40389644"],"is_preprint":false,"attribution":[{"species":"Toxoplasma gondii","strain":""}]},{"year":2025,"finding":"AP2X-1 associates with the HDAC3/MORC complex at promoters of bradyzoite- and sexual stage-specific genes; loss of ap2X-1 leads to upregulation of these genes and increased chromatin accessibility at their promoters, suggesting AP2X-1 modulates MORC/HDAC3 complex function to repress bradyzoite differentiation.","method":"CUT&Tag, ATAC-seq, co-immunoprecipitation, conditional knockout, single-cell RNA sequencing","journal":"mBio","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — CUT&Tag and ATAC-seq with conditional KO phenotype, Co-IP, single lab, multiple orthogonal methods","pmids":["40823841"],"is_preprint":false,"attribution":[{"species":"Toxoplasma gondii","strain":""}]},{"year":2025,"finding":"TgSNF2b (a SWI/SNF ATPase subunit) interacts with MORC to modulate chromatin architecture and gene expression, as shown by co-immunoprecipitation and chromatin accessibility assays.","method":"Co-immunoprecipitation, ATAC-seq, conditional deletion, transcriptomics","journal":"Nature communications","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — Co-IP demonstrating interaction, ATAC-seq showing chromatin effect, single lab","pmids":["41193469"],"is_preprint":false,"attribution":[{"species":"Toxoplasma gondii","strain":""}]}],"current_model":"Toxoplasma gondii MORC is a nuclear transcriptional repressor that operates within a multiprotein complex containing HDAC3 and multiple AP2 transcription factors (including AP2XII-1, AP2XI-2, AP2XII-2, AP2XII-5, AP2IX-4, AP2X-1), recruited to the promoters of sexual and developmental stage-specific genes where it deacetylates histones and compacts chromatin to silence these genes during tachyzoite proliferation; MORC sits downstream of an ISWI-family remodeler (TgSNF2h) and upstream of BFD1 in the epigenetic hierarchy, and its conditional depletion unlocks sexual commitment and merozoite development."},"narrative":{"mechanistic_narrative":"Toxoplasma gondii MORC is a nuclear transcriptional repressor that enforces the asexual tachyzoite program by silencing sexual, merozoite, and bradyzoite stage-specific genes [PMID:32094587, PMID:38093015]. It functions within a multiprotein complex that recruits the histone deacetylase HDAC3 and reduces chromatin accessibility at developmental gene promoters, thereby compacting chromatin to keep these genes off during tachyzoite proliferation [PMID:32094587, PMID:38093015]. MORC is delivered to specific promoters by an array of AP2 transcription factors that provide DNA-binding specificity—including the AP2XII-1/AP2XI-2 heterodimer at merozoite promoters, AP2XII-2, AP2XII-5 (together with the stabilizing protein AIP1), AP2IX-4, and AP2X-1 at bradyzoite/sexual loci [PMID:32938695, PMID:36786611, PMID:38093015, PMID:39716984, PMID:40823841]. As a master regulator, MORC directs the hierarchical expression of secondary AP2 factors and enforces the unidirectionality of the tachyzoite-to-sexual transition; conditional depletion of MORC, or co-depletion of its recruiting AP2 factors, unlocks sexual commitment and drives merozoite development [PMID:32094587, PMID:38093015]. Within the broader epigenetic hierarchy, MORC sits downstream of the ISWI-family remodeler TgSNF2h, which controls transcription-factor access to chromatin, and upstream of the bradyzoite master regulator BFD1 [PMID:40217127, PMID:40389644]; MORC additionally interacts with the SWI/SNF ATPase subunit TgSNF2b to modulate chromatin architecture [PMID:41193469].","teleology":[{"year":2020,"claim":"Establishing how the asexual-stage program suppresses sexual differentiation, this work identified MORC as the repressor that assembles with AP2 factors and HDAC3 to close chromatin at sexual-stage genes.","evidence":"Reciprocal Co-IP, chromatin accessibility assays, and auxin-inducible degron depletion with transcriptomics in T. gondii","pmids":["32094587"],"confidence":"High","gaps":["Direct structural basis of MORC-HDAC3-AP2 complex assembly not resolved","Whether MORC compacts chromatin enzymatically or purely as a scaffold not defined"],"attribution":[{"species":"Toxoplasma gondii","strain":""}]},{"year":2020,"claim":"Framed MORC not just as a local repressor but as a master regulator governing the unidirectionality of the tachyzoite-to-sexual transition by controlling secondary AP2 factor expression.","evidence":"Conditional protein depletion with RNA-seq and ChIP in T. gondii","pmids":["32094587"],"confidence":"High","gaps":["Molecular trigger that normally relieves MORC repression in vivo unknown"],"attribution":[{"species":"Toxoplasma gondii","strain":""}]},{"year":2020,"claim":"Expanded the roster of complex-defining DNA-binding partners by placing AP2IX-4 within the MORC repressor complex.","evidence":"Affinity purification-mass spectrometry of AP2IX-4 interactors in T. gondii","pmids":["32938695"],"confidence":"Medium","gaps":["Genome-wide binding sites and target genes of AP2IX-4 not mapped in this study","Single-lab MS identification"],"attribution":[]},{"year":2023,"claim":"Resolved which AP2 factors provide locus specificity, showing AP2XII-2 co-occupies loci with MORC/HDAC3 and is required to silence a defined subset of sexual-stage genes.","evidence":"CUT&Tag binding mapping plus conditional depletion and transcriptomics in T. gondii","pmids":["36786611"],"confidence":"Medium","gaps":["Single lab","How AP2XII-2 target selection is partitioned from other AP2 factors unclear"],"attribution":[{"species":"Toxoplasma gondii","strain":""}]},{"year":2023,"claim":"Demonstrated the mechanism of MORC recruitment at merozoite promoters: an AP2XII-1/AP2XI-2 heterodimer binds DNA and brings in MORC and HDAC3, and its loss drives a full developmental switch.","evidence":"ChIP, ATAC-seq, conditional co-depletion, transcriptomics, and MS in T. gondii (peer-reviewed, with a preceding bioRxiv preprint)","pmids":["38093015","36711883"],"confidence":"High","gaps":["Whether the heterodimer directly contacts MORC or via an intermediary not defined","Structural interface not resolved"],"attribution":[{"species":"Toxoplasma gondii","strain":""}]},{"year":2024,"claim":"Extended complex composition by identifying AP2XII-5 and a novel stabilizing subunit AIP1 within a nuclear MORC/HDAC3 complex acting at developmentally activated promoters.","evidence":"Co-IP/MS, ChIP, and conditional depletion in T. gondii","pmids":["39716984"],"confidence":"Medium","gaps":["Biochemical role of AIP1 in complex stability not mechanistically dissected","Single lab"],"attribution":[]},{"year":2024,"claim":"Corroborated that AP2XII-1/AP2XI-2 loss de-represses MORC-HDAC3 merozoite targets and that AP2XII-1 organizes a subset of AP2 factors.","evidence":"IP-MS, conditional knockout, and transcriptomics in T. gondii","pmids":["38791568"],"confidence":"Medium","gaps":["Single lab","Hierarchy among the interacting AP2 factors not fully ordered"],"attribution":[]},{"year":2025,"claim":"Positioned MORC within a chromatin-remodeling hierarchy by showing the ISWI remodeler TgSNF2h acts epistatically upstream of MORC to control transcription-factor access.","evidence":"Genetic epistasis with conditional depletion, ATAC-seq, and transcriptomics in T. gondii","pmids":["40217127"],"confidence":"Medium","gaps":["Physical relationship between TgSNF2h and the MORC complex not established","Single lab"],"attribution":[]},{"year":2025,"claim":"Connected MORC to the bradyzoite differentiation pathway by placing MORC/HDAC3 epistatically upstream of the master regulator BFD1.","evidence":"Genetic epistasis via conditional depletion with transcriptomics in T. gondii","pmids":["40389644"],"confidence":"Medium","gaps":["Whether MORC represses BFD1 directly at its promoter versus indirectly not distinguished","Single lab"],"attribution":[]},{"year":2025,"claim":"Identified AP2X-1 as an additional recruiter/modulator of the MORC/HDAC3 complex at bradyzoite- and sexual-stage promoters.","evidence":"CUT&Tag, ATAC-seq, Co-IP, conditional knockout, and single-cell RNA-seq in T. gondii","pmids":["40823841"],"confidence":"Medium","gaps":["Single lab","Whether AP2X-1 acts redundantly or in parallel with other AP2 factors unclear"],"attribution":[]},{"year":2025,"claim":"Broadened MORC's remodeling partnerships by demonstrating a physical interaction with the SWI/SNF ATPase subunit TgSNF2b affecting chromatin architecture.","evidence":"Co-IP, ATAC-seq, conditional deletion, and transcriptomics in T. gondii","pmids":["41193469"],"confidence":"Medium","gaps":["Functional consequence of MORC-TgSNF2b interaction on specific gene sets not fully defined","Single lab"],"attribution":[]},{"year":null,"claim":"How MORC physically compacts chromatin, the structural basis of its assembly with HDAC3 and diverse AP2 factors, and the upstream signal that relieves MORC repression to license differentiation remain unresolved.","evidence":"","pmids":[],"confidence":"Medium","gaps":["No structural model of the MORC complex","Mechanism of stage-specific de-repression unknown","Direct vs indirect regulation of BFD1 unresolved"],"attribution":[]}],"mechanism_profile":{"molecular_activity":[],"localization":[],"pathway":[],"complexes":["MORC-HDAC3-AP2 transcriptional repressor complex","AP2XII-5-MORC-HDAC3-AIP1 nuclear complex"],"partners":["HDAC3","AP2XII-1","AP2XI-2","AP2XII-2","AP2XII-5","AP2IX-4","AP2X-1","AIP1","TGSNF2H","TGSNF2B","BFD1"],"other_free_text":["MORC represses sexual-stage, merozoite, and bradyzoite developmental genes during tachyzoite proliferation.","AP2 transcription factors provide DNA-binding specificity for MORC/HDAC3 recruitment to distinct promoter sets.","MORC lies downstream of the ISWI remodeler TgSNF2h and upstream of the bradyzoite master regulator BFD1 in the epigenetic hierarchy.","Conditional depletion of MORC or its recruiting AP2 factors triggers the tachyzoite-to-sexual/merozoite developmental switch."]},"strain_conflicts":[]},"prefetch_data":{},"corpus_meta":[{"pmid":"32094587","id":"PMC_32094587","title":"A MORC-driven transcriptional switch controls Toxoplasma developmental trajectories and sexual commitment.","date":"2020","source":"Nature microbiology","url":"https://pubmed.ncbi.nlm.nih.gov/32094587","citation_count":102,"is_preprint":false},{"pmid":"38093015","id":"PMC_38093015","title":"In vitro production of cat-restricted Toxoplasma pre-sexual stages.","date":"2023","source":"Nature","url":"https://pubmed.ncbi.nlm.nih.gov/38093015","citation_count":52,"is_preprint":false},{"pmid":"36786611","id":"PMC_36786611","title":"Toxoplasma gondii AP2XII-2 Contributes to Transcriptional Repression for Sexual Commitment.","date":"2023","source":"mSphere","url":"https://pubmed.ncbi.nlm.nih.gov/36786611","citation_count":32,"is_preprint":false},{"pmid":"32938695","id":"PMC_32938695","title":"Toxoplasma gondii AP2XII-2 Contributes to Proper Progression through S-Phase of the Cell Cycle.","date":"2020","source":"mSphere","url":"https://pubmed.ncbi.nlm.nih.gov/32938695","citation_count":27,"is_preprint":false},{"pmid":"38791568","id":"PMC_38791568","title":"AP2XII-1 and AP2XI-2 Suppress Schizogony Gene Expression in Toxoplasma gondii.","date":"2024","source":"International journal of molecular sciences","url":"https://pubmed.ncbi.nlm.nih.gov/38791568","citation_count":12,"is_preprint":false},{"pmid":"33961917","id":"PMC_33961917","title":"Recent achievements and doors opened for coccidian parasite research and development through transcriptomics of enteric sexual stages.","date":"2021","source":"Molecular and biochemical parasitology","url":"https://pubmed.ncbi.nlm.nih.gov/33961917","citation_count":11,"is_preprint":false},{"pmid":"40217127","id":"PMC_40217127","title":"An ISWI-related chromatin remodeller regulates stage-specific gene expression in Toxoplasma gondii.","date":"2025","source":"Nature microbiology","url":"https://pubmed.ncbi.nlm.nih.gov/40217127","citation_count":7,"is_preprint":false},{"pmid":"39716984","id":"PMC_39716984","title":"A Novel Nuclear Protein Complex Controlling the Expression of Developmentally Regulated Genes in Toxoplasma Gondii.","date":"2024","source":"Advanced science (Weinheim, Baden-Wurttemberg, Germany)","url":"https://pubmed.ncbi.nlm.nih.gov/39716984","citation_count":5,"is_preprint":false},{"pmid":"36711883","id":"PMC_36711883","title":"In vitro production of cat-restricted Toxoplasma pre-sexual stages by epigenetic reprogramming.","date":"2023","source":"bioRxiv : the preprint server for biology","url":"https://pubmed.ncbi.nlm.nih.gov/36711883","citation_count":5,"is_preprint":false},{"pmid":"41108686","id":"PMC_41108686","title":"Enhancing pre-sexual and sexual differentiation of Toxoplasma gondii using retinal epithelial cells and intestinal organoids.","date":"2025","source":"Cell reports","url":"https://pubmed.ncbi.nlm.nih.gov/41108686","citation_count":4,"is_preprint":false},{"pmid":"40389644","id":"PMC_40389644","title":"Uncovering biomarkers for chronic toxoplasmosis detection highlights alternative pathways shaping parasite dormancy.","date":"2025","source":"EMBO molecular medicine","url":"https://pubmed.ncbi.nlm.nih.gov/40389644","citation_count":3,"is_preprint":false},{"pmid":"40823841","id":"PMC_40823841","title":"AP2X-1 is a negative regulator of Toxoplasma gondii sexual commitment.","date":"2025","source":"mBio","url":"https://pubmed.ncbi.nlm.nih.gov/40823841","citation_count":1,"is_preprint":false},{"pmid":"40886497","id":"PMC_40886497","title":"Decoding the epigenetic blueprint behind Toxoplasma (pre)sexual commitment and chronic persistence.","date":"2025","source":"Current opinion in microbiology","url":"https://pubmed.ncbi.nlm.nih.gov/40886497","citation_count":1,"is_preprint":false},{"pmid":"41193469","id":"PMC_41193469","title":"Toxoplasma gondii chromatin remodeler SWI/SNF controls parasite division and gene expression.","date":"2025","source":"Nature communications","url":"https://pubmed.ncbi.nlm.nih.gov/41193469","citation_count":0,"is_preprint":false},{"pmid":"41686642","id":"PMC_41686642","title":"Protocol to enhance pre-sexual and sexual differentiation of Toxoplasma gondii using retinal cells and intestinal organoid-derived monolayers.","date":"2026","source":"STAR protocols","url":"https://pubmed.ncbi.nlm.nih.gov/41686642","citation_count":0,"is_preprint":false}],"cost":{"stage1":{"model":"claude-sonnet-4-6","input_tokens":9391,"output_tokens":2831,"usd":0.035319,"stage1_stop_reason":"end_turn"},"stage2":{"model":"claude-opus-4-8","input_tokens":8664,"output_tokens":4070,"usd":0.072535,"stage2_stop_reason":"end_turn"},"total_usd":0.107854,"stage1_batch_id":"msgbatch_01S6GjoYQm8LTPUsdhASdqag","stage2_batch_id":"msgbatch_01VX63RTMdBJqsG6gQMqoCjz","note":"batch pricing = 50% of standard"},"stage1_raw":"```json\n{\n  \"discoveries\": [\n    {\n      \"year\": 2020,\n      \"finding\": \"Toxoplasma gondii MORC forms a complex with AP2 transcription factors and recruits histone deacetylase HDAC3, thereby reducing chromatin accessibility at genes exclusively expressed during sexual stages and functioning as a transcriptional repressor of sexual commitment.\",\n      \"method\": \"Co-immunoprecipitation, chromatin accessibility assays, conditional depletion (auxin-inducible degron), transcriptomic analysis\",\n      \"journal\": \"Nature microbiology\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — reciprocal Co-IP establishing complex, chromatin accessibility assays, conditional KD with defined transcriptional phenotype, replicated across multiple subsequent studies\",\n      \"pmids\": [\"32094587\"],\n      \"is_preprint\": false,\n      \"attribution\": [{\"species\": \"Toxoplasma gondii\", \"strain\": \"\"}]\n    },\n    {\n      \"year\": 2020,\n      \"finding\": \"MORC acts as a master regulator that directs hierarchical expression of secondary AP2 transcription factors, controlling the unidirectionality of the tachyzoite-to-sexual stage transition; conditional MORC depletion causes a shift from asexual proliferation to sexual differentiation.\",\n      \"method\": \"Conditional protein depletion, RNA-seq transcriptomics, chromatin immunoprecipitation\",\n      \"journal\": \"Nature microbiology\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — conditional KD with defined transcriptional and developmental phenotype, multiple orthogonal methods, replicated in subsequent studies\",\n      \"pmids\": [\"32094587\"],\n      \"is_preprint\": false,\n      \"attribution\": [{\"species\": \"Toxoplasma gondii\", \"strain\": \"\"}]\n    },\n    {\n      \"year\": 2020,\n      \"finding\": \"AP2IX-4 is a component of the MORC transcriptional repressor complex, identified by purification of AP2IX-4-interacting proteins.\",\n      \"method\": \"Co-immunoprecipitation and mass spectrometry (affinity purification-MS)\",\n      \"journal\": \"mSphere\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — affinity purification-MS identifying complex membership, single lab\",\n      \"pmids\": [\"32938695\"],\n      \"is_preprint\": false,\n      \"attribution\": [{\"species\": \"Toxoplasma gondii\", \"strain\": \"\"}]\n    },\n    {\n      \"year\": 2023,\n      \"finding\": \"AP2XII-2 associates at genomic loci with HDAC3 and MORC and is required for silencing of a subset of sexual stage genes including AP2X-10 and AAH1, as shown by CUT&Tag mapping and conditional depletion.\",\n      \"method\": \"CUT&Tag (cleavage under targets and tagmentation), conditional depletion, transcriptomic analysis\",\n      \"journal\": \"mSphere\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — CUT&Tag genome-wide binding mapped with conditional KD phenotype, single lab, two orthogonal methods\",\n      \"pmids\": [\"36786611\"],\n      \"is_preprint\": false,\n      \"attribution\": [{\"species\": \"Toxoplasma gondii\", \"strain\": \"\"}]\n    },\n    {\n      \"year\": 2023,\n      \"finding\": \"AP2XII-1 and AP2XI-2 bind DNA as heterodimers at merozoite promoters in tachyzoites and recruit MORC and HDAC3 to restrict chromatin accessibility and silence merozoite genes; simultaneous depletion of these factors causes full tachyzoite-to-merozoite transition.\",\n      \"method\": \"Chromatin immunoprecipitation, chromatin accessibility assays (ATAC-seq), conditional co-depletion, transcriptomics, mass spectrometry\",\n      \"journal\": \"Nature\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — reciprocal Co-IP, ATAC-seq, conditional co-KD with defined developmental phenotype, multiple orthogonal methods, published in peer-reviewed journal\",\n      \"pmids\": [\"38093015\"],\n      \"is_preprint\": false,\n      \"attribution\": [{\"species\": \"Toxoplasma gondii\", \"strain\": \"\"}]\n    },\n    {\n      \"year\": 2023,\n      \"finding\": \"AP2XII-1 and AP2XI-2 recruit MORC and HDAC3 to merozoite promoters to restrict chromatin accessibility (preprint version of the Nature 2023 paper).\",\n      \"method\": \"ChIP, ATAC-seq, conditional co-depletion, mass spectrometry\",\n      \"journal\": \"bioRxiv\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — preprint superseded by peer-reviewed publication (PMID:38093015); included as corroborating evidence\",\n      \"pmids\": [\"36711883\"],\n      \"is_preprint\": true,\n      \"attribution\": [{\"species\": \"Toxoplasma gondii\", \"strain\": \"\"}]\n    },\n    {\n      \"year\": 2024,\n      \"finding\": \"AP2XII-5 forms a nuclear complex with MORC, HDAC3, and a novel stabilizing protein AIP1; AP2XII-5 binds promoters of developmentally activated genes and recruits MORC and HDAC3 to suppress their expression in tachyzoites.\",\n      \"method\": \"Co-immunoprecipitation, mass spectrometry, chromatin immunoprecipitation, conditional depletion\",\n      \"journal\": \"Advanced science\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — Co-IP/MS identifying complex, ChIP mapping binding, conditional KD with transcriptional phenotype, single lab\",\n      \"pmids\": [\"39716984\"],\n      \"is_preprint\": false,\n      \"attribution\": [{\"species\": \"Toxoplasma gondii\", \"strain\": \"\"}]\n    },\n    {\n      \"year\": 2024,\n      \"finding\": \"AP2XII-1 and AP2XI-2 conditional knockout causes upregulation of merozoite-specific genes targeted by the MORC-HDAC3 complex, with AP2XII-1 specifically binding to a subset of AP2 transcription factors including AP2XI-2.\",\n      \"method\": \"Immunoprecipitation, mass spectrometry, conditional knockout, transcriptomics\",\n      \"journal\": \"International journal of molecular sciences\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — IP-MS and conditional KO with defined transcriptional phenotype, single lab\",\n      \"pmids\": [\"38791568\"],\n      \"is_preprint\": false,\n      \"attribution\": [{\"species\": \"Toxoplasma gondii\", \"strain\": \"\"}]\n    },\n    {\n      \"year\": 2025,\n      \"finding\": \"TgSNF2h (an ISWI chromatin remodeler) exerts epistatic control over MORC by modulating chromatin accessibility to transcription factors, placing TgSNF2h upstream of MORC in the epigenetic regulatory hierarchy for developmental gene regulation.\",\n      \"method\": \"Genetic epistasis analysis, conditional depletion, ATAC-seq chromatin accessibility, transcriptomics\",\n      \"journal\": \"Nature microbiology\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — epistasis established by genetic depletion with ATAC-seq readout, single lab\",\n      \"pmids\": [\"40217127\"],\n      \"is_preprint\": false,\n      \"attribution\": [{\"species\": \"Toxoplasma gondii\", \"strain\": \"\"}]\n    },\n    {\n      \"year\": 2025,\n      \"finding\": \"MORC and HDAC3 epistatically regulate BFD1, a key bradyzoite transcriptional regulator, placing MORC upstream of BFD1 in the bradyzoite differentiation pathway.\",\n      \"method\": \"Genetic epistasis analysis, conditional depletion, transcriptomics\",\n      \"journal\": \"EMBO molecular medicine\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — epistasis by conditional depletion with transcriptional readout, single lab\",\n      \"pmids\": [\"40389644\"],\n      \"is_preprint\": false,\n      \"attribution\": [{\"species\": \"Toxoplasma gondii\", \"strain\": \"\"}]\n    },\n    {\n      \"year\": 2025,\n      \"finding\": \"AP2X-1 associates with the HDAC3/MORC complex at promoters of bradyzoite- and sexual stage-specific genes; loss of ap2X-1 leads to upregulation of these genes and increased chromatin accessibility at their promoters, suggesting AP2X-1 modulates MORC/HDAC3 complex function to repress bradyzoite differentiation.\",\n      \"method\": \"CUT&Tag, ATAC-seq, co-immunoprecipitation, conditional knockout, single-cell RNA sequencing\",\n      \"journal\": \"mBio\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — CUT&Tag and ATAC-seq with conditional KO phenotype, Co-IP, single lab, multiple orthogonal methods\",\n      \"pmids\": [\"40823841\"],\n      \"is_preprint\": false,\n      \"attribution\": [{\"species\": \"Toxoplasma gondii\", \"strain\": \"\"}]\n    },\n    {\n      \"year\": 2025,\n      \"finding\": \"TgSNF2b (a SWI/SNF ATPase subunit) interacts with MORC to modulate chromatin architecture and gene expression, as shown by co-immunoprecipitation and chromatin accessibility assays.\",\n      \"method\": \"Co-immunoprecipitation, ATAC-seq, conditional deletion, transcriptomics\",\n      \"journal\": \"Nature communications\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — Co-IP demonstrating interaction, ATAC-seq showing chromatin effect, single lab\",\n      \"pmids\": [\"41193469\"],\n      \"is_preprint\": false,\n      \"attribution\": [{\"species\": \"Toxoplasma gondii\", \"strain\": \"\"}]\n    }\n  ],\n  \"current_model\": \"Toxoplasma gondii MORC is a nuclear transcriptional repressor that operates within a multiprotein complex containing HDAC3 and multiple AP2 transcription factors (including AP2XII-1, AP2XI-2, AP2XII-2, AP2XII-5, AP2IX-4, AP2X-1), recruited to the promoters of sexual and developmental stage-specific genes where it deacetylates histones and compacts chromatin to silence these genes during tachyzoite proliferation; MORC sits downstream of an ISWI-family remodeler (TgSNF2h) and upstream of BFD1 in the epigenetic hierarchy, and its conditional depletion unlocks sexual commitment and merozoite development.\"\n}\n```","stage2_raw":"{\n  \"mechanistic_narrative\": \"Toxoplasma gondii MORC is a nuclear transcriptional repressor that enforces the asexual tachyzoite program by silencing sexual, merozoite, and bradyzoite stage-specific genes [#0, #1, #4]. It functions within a multiprotein complex that recruits the histone deacetylase HDAC3 and reduces chromatin accessibility at developmental gene promoters, thereby compacting chromatin to keep these genes off during tachyzoite proliferation [#0, #4]. MORC is delivered to specific promoters by an array of AP2 transcription factors that provide DNA-binding specificity—including the AP2XII-1/AP2XI-2 heterodimer at merozoite promoters, AP2XII-2, AP2XII-5 (together with the stabilizing protein AIP1), AP2IX-4, and AP2X-1 at bradyzoite/sexual loci [#2, #3, #4, #6, #10]. As a master regulator, MORC directs the hierarchical expression of secondary AP2 factors and enforces the unidirectionality of the tachyzoite-to-sexual transition; conditional depletion of MORC, or co-depletion of its recruiting AP2 factors, unlocks sexual commitment and drives merozoite development [#1, #4]. Within the broader epigenetic hierarchy, MORC sits downstream of the ISWI-family remodeler TgSNF2h, which controls transcription-factor access to chromatin, and upstream of the bradyzoite master regulator BFD1 [#8, #9]; MORC additionally interacts with the SWI/SNF ATPase subunit TgSNF2b to modulate chromatin architecture [#11].\",\n  \"teleology\": [\n    {\n      \"year\": 2020,\n      \"claim\": \"Establishing how the asexual-stage program suppresses sexual differentiation, this work identified MORC as the repressor that assembles with AP2 factors and HDAC3 to close chromatin at sexual-stage genes.\",\n      \"evidence\": \"Reciprocal Co-IP, chromatin accessibility assays, and auxin-inducible degron depletion with transcriptomics in T. gondii\",\n      \"pmids\": [\"32094587\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Direct structural basis of MORC-HDAC3-AP2 complex assembly not resolved\", \"Whether MORC compacts chromatin enzymatically or purely as a scaffold not defined\"],\n      \"attribution\": [{\"species\": \"Toxoplasma gondii\", \"strain\": \"\"}]\n    },\n    {\n      \"year\": 2020,\n      \"claim\": \"Framed MORC not just as a local repressor but as a master regulator governing the unidirectionality of the tachyzoite-to-sexual transition by controlling secondary AP2 factor expression.\",\n      \"evidence\": \"Conditional protein depletion with RNA-seq and ChIP in T. gondii\",\n      \"pmids\": [\"32094587\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Molecular trigger that normally relieves MORC repression in vivo unknown\"],\n      \"attribution\": [{\"species\": \"Toxoplasma gondii\", \"strain\": \"\"}]\n    },\n    {\n      \"year\": 2020,\n      \"claim\": \"Expanded the roster of complex-defining DNA-binding partners by placing AP2IX-4 within the MORC repressor complex.\",\n      \"evidence\": \"Affinity purification-mass spectrometry of AP2IX-4 interactors in T. gondii\",\n      \"pmids\": [\"32938695\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Genome-wide binding sites and target genes of AP2IX-4 not mapped in this study\", \"Single-lab MS identification\"]\n    },\n    {\n      \"year\": 2023,\n      \"claim\": \"Resolved which AP2 factors provide locus specificity, showing AP2XII-2 co-occupies loci with MORC/HDAC3 and is required to silence a defined subset of sexual-stage genes.\",\n      \"evidence\": \"CUT&Tag binding mapping plus conditional depletion and transcriptomics in T. gondii\",\n      \"pmids\": [\"36786611\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Single lab\", \"How AP2XII-2 target selection is partitioned from other AP2 factors unclear\"],\n      \"attribution\": [{\"species\": \"Toxoplasma gondii\", \"strain\": \"\"}]\n    },\n    {\n      \"year\": 2023,\n      \"claim\": \"Demonstrated the mechanism of MORC recruitment at merozoite promoters: an AP2XII-1/AP2XI-2 heterodimer binds DNA and brings in MORC and HDAC3, and its loss drives a full developmental switch.\",\n      \"evidence\": \"ChIP, ATAC-seq, conditional co-depletion, transcriptomics, and MS in T. gondii (peer-reviewed, with a preceding bioRxiv preprint)\",\n      \"pmids\": [\"38093015\", \"36711883\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Whether the heterodimer directly contacts MORC or via an intermediary not defined\", \"Structural interface not resolved\"],\n      \"attribution\": [{\"species\": \"Toxoplasma gondii\", \"strain\": \"\"}]\n    },\n    {\n      \"year\": 2024,\n      \"claim\": \"Extended complex composition by identifying AP2XII-5 and a novel stabilizing subunit AIP1 within a nuclear MORC/HDAC3 complex acting at developmentally activated promoters.\",\n      \"evidence\": \"Co-IP/MS, ChIP, and conditional depletion in T. gondii\",\n      \"pmids\": [\"39716984\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Biochemical role of AIP1 in complex stability not mechanistically dissected\", \"Single lab\"]\n    },\n    {\n      \"year\": 2024,\n      \"claim\": \"Corroborated that AP2XII-1/AP2XI-2 loss de-represses MORC-HDAC3 merozoite targets and that AP2XII-1 organizes a subset of AP2 factors.\",\n      \"evidence\": \"IP-MS, conditional knockout, and transcriptomics in T. gondii\",\n      \"pmids\": [\"38791568\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Single lab\", \"Hierarchy among the interacting AP2 factors not fully ordered\"]\n    },\n    {\n      \"year\": 2025,\n      \"claim\": \"Positioned MORC within a chromatin-remodeling hierarchy by showing the ISWI remodeler TgSNF2h acts epistatically upstream of MORC to control transcription-factor access.\",\n      \"evidence\": \"Genetic epistasis with conditional depletion, ATAC-seq, and transcriptomics in T. gondii\",\n      \"pmids\": [\"40217127\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Physical relationship between TgSNF2h and the MORC complex not established\", \"Single lab\"]\n    },\n    {\n      \"year\": 2025,\n      \"claim\": \"Connected MORC to the bradyzoite differentiation pathway by placing MORC/HDAC3 epistatically upstream of the master regulator BFD1.\",\n      \"evidence\": \"Genetic epistasis via conditional depletion with transcriptomics in T. gondii\",\n      \"pmids\": [\"40389644\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Whether MORC represses BFD1 directly at its promoter versus indirectly not distinguished\", \"Single lab\"]\n    },\n    {\n      \"year\": 2025,\n      \"claim\": \"Identified AP2X-1 as an additional recruiter/modulator of the MORC/HDAC3 complex at bradyzoite- and sexual-stage promoters.\",\n      \"evidence\": \"CUT&Tag, ATAC-seq, Co-IP, conditional knockout, and single-cell RNA-seq in T. gondii\",\n      \"pmids\": [\"40823841\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Single lab\", \"Whether AP2X-1 acts redundantly or in parallel with other AP2 factors unclear\"]\n    },\n    {\n      \"year\": 2025,\n      \"claim\": \"Broadened MORC's remodeling partnerships by demonstrating a physical interaction with the SWI/SNF ATPase subunit TgSNF2b affecting chromatin architecture.\",\n      \"evidence\": \"Co-IP, ATAC-seq, conditional deletion, and transcriptomics in T. gondii\",\n      \"pmids\": [\"41193469\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Functional consequence of MORC-TgSNF2b interaction on specific gene sets not fully defined\", \"Single lab\"]\n    },\n    {\n      \"year\": null,\n      \"claim\": \"How MORC physically compacts chromatin, the structural basis of its assembly with HDAC3 and diverse AP2 factors, and the upstream signal that relieves MORC repression to license differentiation remain unresolved.\",\n      \"evidence\": \"\",\n      \"pmids\": [],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"No structural model of the MORC complex\", \"Mechanism of stage-specific de-repression unknown\", \"Direct vs indirect regulation of BFD1 unresolved\"]\n    }\n  ],\n  \"mechanism_profile\": {\n    \"molecular_activity\": [\n      {\"term_id\": \"GO:0003714\", \"supporting_discovery_ids\": [0, 1, 4], \"attribution\": [{\"species\": \"Toxoplasma gondii\", \"strain\": \"\"}]},\n      {\"term_id\": \"GO:0031491\", \"supporting_discovery_ids\": [0, 4], \"attribution\": [{\"species\": \"Toxoplasma gondii\", \"strain\": \"\"}]}\n    ],\n    \"localization\": [\n      {\"term_id\": \"GO:0005634\", \"supporting_discovery_ids\": [0, 6], \"attribution\": [{\"species\": \"Toxoplasma gondii\", \"strain\": \"\"}]}\n    ],\n    \"pathway\": [\n      {\"term_id\": \"GO:0045892\", \"supporting_discovery_ids\": [0, 3, 4, 6, 10], \"attribution\": [{\"species\": \"Toxoplasma gondii\", \"strain\": \"\"}]},\n      {\"term_id\": \"GO:0006338\", \"supporting_discovery_ids\": [0, 4, 8, 11], \"attribution\": [{\"species\": \"Toxoplasma gondii\", \"strain\": \"\"}]},\n      {\"term_id\": \"GO:0030154\", \"supporting_discovery_ids\": [1, 4, 9], \"attribution\": [{\"species\": \"Toxoplasma gondii\", \"strain\": \"\"}]}\n    ],\n    \"complexes\": [\n      \"MORC-HDAC3-AP2 transcriptional repressor complex\",\n      \"AP2XII-5-MORC-HDAC3-AIP1 nuclear complex\"\n    ],\n    \"partners\": [\n      \"HDAC3\",\n      \"AP2XII-1\",\n      \"AP2XI-2\",\n      \"AP2XII-2\",\n      \"AP2XII-5\",\n      \"AP2IX-4\",\n      \"AP2X-1\",\n      \"AIP1\",\n      \"TgSNF2h\",\n      \"TgSNF2b\",\n      \"BFD1\"\n    ],\n    \"other_free_text\": [\n      \"MORC represses sexual-stage, merozoite, and bradyzoite developmental genes during tachyzoite proliferation.\",\n      \"AP2 transcription factors provide DNA-binding specificity for MORC/HDAC3 recruitment to distinct promoter sets.\",\n      \"MORC lies downstream of the ISWI remodeler TgSNF2h and upstream of the bradyzoite master regulator BFD1 in the epigenetic hierarchy.\",\n      \"Conditional depletion of MORC or its recruiting AP2 factors triggers the tachyzoite-to-sexual/merozoite developmental switch.\"\n    ]\n  },\n  \"strain_conflicts\": []\n}","audit_flag":null,"strains":[{"strain":"ME49","gene_id":"TGME49_305340","name":"MORC","product":"ATPase MORC","uniprot_acc":"S8EVD3","chromosome":"TGME49_chrIX","start_pos":5374557},{"strain":"GT1","gene_id":"TGGT1_305340","name":null,"product":"corepressor complex CRC230","uniprot_acc":null,"chromosome":"TGGT1_chrIX","start_pos":5155746},{"strain":"RH88","gene_id":"TGRH88_017080","name":null,"product":"corepressor complex CRC230","uniprot_acc":null,"chromosome":"CM023090","start_pos":5498110},{"strain":"VEG","gene_id":"TGVEG_305340","name":null,"product":"corepressor complex CRC230","uniprot_acc":"A0A0F7V117","chromosome":"TGVEG_chrIX","start_pos":5413659}]}