{"gene":"B9D1","run_date":"2026-06-09T22:02:44","timeline":{"discoveries":[{"year":2011,"finding":"B9D1 is a component of a transition zone complex (with Mks1, Tmem216, Tmem67, Cep290, Tctn2, Cc2d2a, and Tctn1) that co-localizes at the ciliary transition zone and regulates ciliary assembly and trafficking of membrane-associated proteins including Arl13b, AC3, Smoothened, and Pkd2.","method":"Co-immunoprecipitation, immunofluorescence co-localization, mouse genetics (knockout)","journal":"Nature genetics","confidence":"High","confidence_rationale":"Tier 2 / Strong — reciprocal Co-IP and co-localization, replicated across multiple labs and studies","pmids":["21725307"],"is_preprint":false},{"year":2011,"finding":"B9D1 localizes to the ciliary transition zone interdependently with TMEM231 and CC2D2A (and in a Sept2-regulated fashion); disruption of this complex reduces cilia formation, removes signaling receptors from cilia, and increases the rate of diffusion into the ciliary membrane, demonstrating that B9D1 is essential for maintaining the ciliary membrane as a diffusion barrier.","method":"RNAi knockdown, proteomics, mouse knockout, fluorescence recovery after photobleaching (FRAP), co-localization immunofluorescence","journal":"Nature cell biology","confidence":"High","confidence_rationale":"Tier 2 / Strong — multiple orthogonal methods (RNAi, mouse KO, FRAP, proteomics), single rigorous study with functional readouts","pmids":["22179047"],"is_preprint":false},{"year":2011,"finding":"Mice lacking B9d1 display polydactyly, kidney cysts, ductal plate malformations, and abnormal neural tube patterning, with compromised ciliogenesis, ciliary protein localization, and Hedgehog signal transduction. Co-immunoprecipitation and mass spectrometry showed that Mks1, B9d1, and B9d2 physically interact as a complex.","method":"Mouse knockout (B9d1-null), co-immunoprecipitation, mass spectrometry, zebrafish rescue assay","journal":"American journal of human genetics","confidence":"High","confidence_rationale":"Tier 2 / Strong — mouse KO with defined cellular phenotype plus Co-IP/MS protein interaction, replicated across studies","pmids":["21763481"],"is_preprint":false},{"year":2008,"finding":"The C. elegans B9D1 ortholog TZA-2 (MKSR-1) forms a complex with the other B9 proteins (XBX-7/MKS1 and TZA-1/B9D2) that localizes to the base of cilia (transition zone/basal body). Single B9 gene mutations do not overtly affect cilia, but combinations with nph-1 or nph-4 mutations cause ciliogenesis and dendrite formation defects, indicating functional redundancy between B9 proteins and nephrocystins.","method":"C. elegans genetics (single and double mutants), fluorescence microscopy localization","journal":"Molecular biology of the cell","confidence":"High","confidence_rationale":"Tier 2 / Strong — genetic epistasis with defined phenotypic readout, replicated across multiple papers","pmids":["18337471"],"is_preprint":false},{"year":2009,"finding":"C. elegans MKSR-1 (B9D1 ortholog) and MKSR-2 (B9D2 ortholog) localize to transition zones/basal bodies of sensory cilia in a co-dependent manner with MKS-1. Disrupting human MKSR1 (B9D1) causes ciliogenesis defects. Genetic interactions between all double mks/mksr mutant combinations manifest as increased lifespan due to abnormal insulin-IGF-I signaling.","method":"C. elegans fluorescence microscopy, RNAi knockdown of human MKSR1, genetic epistasis analysis","journal":"Journal of cell science","confidence":"High","confidence_rationale":"Tier 2 / Strong — multiple orthogonal methods (localization, human RNAi, C. elegans genetics), conserved findings across organisms","pmids":["19208769"],"is_preprint":false},{"year":2020,"finding":"The B9D protein complex interaction mode is MKS1-B9D2-B9D1 (not a simple trimeric hub), with interdependent localization to the transition zone. MKS1-KO and B9D2-KO cells show that B9D proteins are involved in, though not essential for, cilia biogenesis, but formation of the full B9D complex is crucial for establishing a diffusion barrier for ciliary membrane proteins.","method":"Knockout cell lines (MKS1-KO, B9D2-KO), rescue experiments, co-immunoprecipitation, immunofluorescence, diffusion assay","journal":"Molecular biology of the cell","confidence":"High","confidence_rationale":"Tier 2 / Strong — KO cell lines with rescue, Co-IP defining interaction mode, functional diffusion barrier assay — multiple orthogonal methods in one study","pmids":["32726168"],"is_preprint":false},{"year":2015,"finding":"Tmem231 and B9d1 are mutually required for each other's localization to the transition zone, and both are required for other MKS complex components such as Mks1 to localize to the transition zone. Loss of Tmem231 or B9d1 disrupts localization of ciliary proteins including Arl13b and Inpp5e, causing MKS-like phenotypes.","method":"Mouse knockout, immunofluorescence co-localization","journal":"The Journal of cell biology","confidence":"High","confidence_rationale":"Tier 2 / Strong — mouse KO with defined phenotype and mutual dependency of localization demonstrated, replicated across labs","pmids":["25869670"],"is_preprint":false},{"year":2017,"finding":"Using BiFC (bimolecular fluorescence complementation) assay, B9D1 and AHI1 interact with the transmembrane protein SSTR3, spatially mapping to the outer region of the ciliary gating zone. B9D1 exhibits little to no turnover at the transition zone (stable component), as shown by FRAP analysis.","method":"BiFC assay, FRAP (fluorescence recovery after photobleaching)","journal":"Current biology : CB","confidence":"Medium","confidence_rationale":"Tier 2 / Weak — novel BiFC mapping and FRAP in a single lab, single study; no replication","pmids":["28736169"],"is_preprint":false},{"year":2015,"finding":"Blocking TGF-β/Smad2 signaling in Xenopus results in the absence of B9D1/MKSR-1 from cilia in multi-ciliated cells, indicating that TGF-β signaling controls B9D1 localization to the transition zone and is required for normal transition zone function.","method":"Xenopus in vivo signaling blockade (dominant-negative Smad2), immunofluorescence","journal":"Cell reports","confidence":"Medium","confidence_rationale":"Tier 2 / Weak — defined upstream regulator of B9D1 localization, single lab, single model organism study","pmids":["25959824"],"is_preprint":false},{"year":2011,"finding":"In C. elegans, JBTS-14/TMEM237 functionally interacts with MKSR-1/B9D1 and MKSR-2/B9D2 to control basal body-transition zone anchoring to the membrane and ciliogenesis, placing B9D1 in a genetic interaction network with TMEM237 and RPGRIP1L/MKS5.","method":"C. elegans genetic epistasis, fluorescence microscopy","journal":"American journal of human genetics","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — genetic epistasis with defined phenotype in C. elegans, orthogonal to other localization studies","pmids":["22152675"],"is_preprint":false},{"year":2025,"finding":"The B9D1-B9D2-MKS1 complex interacts with and anchors TMEM67 to the transition zone membrane; disruption of this complex reduces posttranslational modifications of axonemal microtubules by deregulating tubulin-modifying enzymes within cilia. Additionally, B9D1 localizes to centrioles prior to ciliogenesis, where it facilitates the initiation of ciliogenesis.","method":"Co-immunoprecipitation, knockout cell analysis, immunofluorescence, posttranslational modification assays","journal":"The Journal of clinical investigation","confidence":"Medium","confidence_rationale":"Tier 2 / Weak — multiple functional readouts in a single recent study, not yet independently replicated","pmids":["41165761"],"is_preprint":false},{"year":2025,"finding":"In Xenopus multiciliated cells, B9d1 is not present in the cilia precursor pool; cycloheximide treatment blocking protein synthesis prevents B9d1 from appearing at regenerating transition zones, demonstrating that B9d1 requires new transcription/translation for transition zone assembly during cilia regeneration.","method":"Cycloheximide protein synthesis blockade, live imaging, immunofluorescence in Xenopus MCCs","journal":"EMBO reports","confidence":"Medium","confidence_rationale":"Tier 2 / Weak — direct experimental evidence for B9d1 not being in precursor pool, single lab, single study, preprint version also available","pmids":["40087471"],"is_preprint":false},{"year":2012,"finding":"In C. elegans, mksr-1 (B9D1 ortholog) genetically interacts with nphp-2 (inversin) in a sensilla-dependent manner to control cilia formation and placement, placing B9D1 in the MKS genetic pathway that modifies NPHP pathway function.","method":"C. elegans genetic epistasis (double mutants), fluorescence microscopy","journal":"Journal of cell science","confidence":"Low","confidence_rationale":"Tier 3 / Weak — C. elegans genetic interaction, single lab, no mechanistic molecular detail beyond pathway placement","pmids":["22393243"],"is_preprint":false},{"year":2025,"finding":"Ahi1 knockdown in mouse dorsal raphe nucleus reduces B9D1 levels; overexpression of B9D1 rescues ASD-like behaviors and 5-HT system dysfunction caused by Ahi1 knockdown or GDM exposure, placing B9D1 downstream of Ahi1 in an Ahi1/B9D1/Shh axis that regulates serotonergic function.","method":"AAV-mediated Ahi1 knockdown in mouse brain, B9D1 overexpression rescue, behavioral assays, in vitro LPS neuroinflammation model","journal":"Brain, behavior, and immunity","confidence":"Low","confidence_rationale":"Tier 3 / Weak — single lab, pathway placement by rescue experiment, mechanism downstream of Ahi1 not directly biochemically characterized in this abstract","pmids":["41038357"],"is_preprint":false}],"current_model":"B9D1 is a stable, soluble transition zone protein that forms a tripartite complex with B9D2 and MKS1 (in the order MKS1-B9D2-B9D1), localizes to the outer region of the ciliary gating zone in a manner interdependent with TMEM231 and CC2D2A, anchors TMEM67 to the transition zone membrane, acts as a diffusion barrier to maintain ciliary membrane compartmentalization, facilitates the initiation of ciliogenesis at centrioles, and regulates posttranslational modifications of axonemal microtubules; loss of B9D1 compromises Hedgehog signaling, ciliogenesis, and ciliary protein localization, causing ciliopathies including Meckel syndrome and Joubert syndrome."},"narrative":{"mechanistic_narrative":"B9D1 is a stable, soluble transition zone protein that controls the ciliary gating apparatus by forming a defined module of the Meckel syndrome (MKS) complex and enforcing the diffusion barrier that compartmentalizes the ciliary membrane [PMID:21725307, PMID:22179047]. It assembles into a tripartite unit with B9D2 and MKS1 in the linear arrangement MKS1-B9D2-B9D1 rather than a simple trimeric hub, and formation of the full complex is required to establish a diffusion barrier for ciliary membrane proteins [PMID:32726168, PMID:21763481]. B9D1 localizes to the transition zone interdependently with TMEM231 and CC2D2A, and this mutual dependency is needed to recruit other MKS components such as MKS1 and to retain ciliary signaling proteins including ARL13B, INPP5E, Smoothened, and PKD2; loss of B9D1 increases the diffusion rate into the ciliary membrane, depletes signaling receptors from cilia, and compromises Hedgehog signal transduction [PMID:21725307, PMID:22179047, PMID:25869670]. Within this module B9D1 anchors TMEM67 to the transition zone membrane and constrains tubulin-modifying enzymes so that loss of the complex deregulates posttranslational modification of axonemal microtubules; B9D1 also localizes to centrioles before ciliogenesis to facilitate its initiation [PMID:41165761]. As a stable, low-turnover transition zone component spatially mapped to the outer ciliary gating zone, it interacts with SSTR3 and AHI1 [PMID:28736169]. B9D1 is a ciliopathy gene whose loss in mice produces polydactyly, kidney cysts, ductal plate malformations, and abnormal neural tube patterning, recapitulating Meckel syndrome-like and Joubert syndrome phenotypes [PMID:21763481].","teleology":[{"year":2008,"claim":"Established that the B9D1 ortholog is not an isolated protein but a member of a conserved B9-protein module at the ciliary base, answering whether B9 proteins function together.","evidence":"C. elegans single/double mutant genetics and fluorescence localization of TZA-2/MKSR-1 with XBX-7/MKS1 and TZA-1/B9D2","pmids":["18337471"],"confidence":"High","gaps":["Single B9 mutations cause no overt cilia defect, leaving the non-redundant role unclear","No molecular architecture of the complex","Redundancy with nephrocystins not resolved mechanistically"]},{"year":2009,"claim":"Showed the co-dependence of B9 proteins for transition zone localization is conserved and that the human ortholog is required for ciliogenesis, linking worm genetics to human cilia biology.","evidence":"C. elegans co-localization of MKSR-1/MKSR-2 with MKS-1, RNAi of human MKSR1, and genetic epistasis affecting insulin-IGF-I signaling/lifespan","pmids":["19208769"],"confidence":"High","gaps":["Biochemical basis of co-dependent localization not defined","Direct human protein interactions not shown"]},{"year":2011,"claim":"Defined B9D1 as part of a multi-subunit transition zone complex that gates ciliary membrane protein trafficking, establishing its role in maintaining the ciliary diffusion barrier.","evidence":"Reciprocal Co-IP, immunofluorescence, mouse knockouts, FRAP, and proteomics across multiple studies showing interdependent localization with TMEM231/CC2D2A and mislocalization of Arl13b, Smoothened, AC3, and Pkd2","pmids":["21725307","22179047","21763481"],"confidence":"High","gaps":["Stoichiometry and interaction topology within the complex unresolved","Mechanism by which the barrier is physically established not defined"]},{"year":2011,"claim":"Placed B9D1 in a broader genetic interaction network controlling basal body-transition zone membrane anchoring, connecting the B9 module to TMEM237 and RPGRIP1L/MKS5.","evidence":"C. elegans genetic epistasis and fluorescence microscopy of JBTS-14/TMEM237 with MKSR-1/MKSR-2","pmids":["22152675"],"confidence":"Medium","gaps":["Genetic interaction does not establish direct physical contact","Conservation of the anchoring mechanism in mammals not tested here"]},{"year":2012,"claim":"Positioned B9D1 within the MKS pathway as a modifier of NPHP pathway function in cilia formation and placement.","evidence":"C. elegans double-mutant epistasis of mksr-1 with nphp-2/inversin","pmids":["22393243"],"confidence":"Low","gaps":["No molecular mechanism beyond pathway placement","Sensilla-dependence not mechanistically explained","Not validated in mammalian cells"]},{"year":2015,"claim":"Demonstrated mutual localization dependency between B9D1 and TMEM231 and identified upstream control of B9D1 transition zone targeting, clarifying how the gating module is built and regulated.","evidence":"Mouse knockouts with immunofluorescence (TMEM231/B9D1 interdependency, Arl13b/Inpp5e mislocalization) and Xenopus TGF-β/Smad2 signaling blockade affecting B9D1 ciliary localization","pmids":["25869670","25959824"],"confidence":"Medium","gaps":["How TGF-β/Smad2 signaling mechanistically directs B9D1 localization is unknown","Direct versus indirect TMEM231-B9D1 contact not biochemically resolved"]},{"year":2017,"claim":"Spatially mapped B9D1 to the outer region of the ciliary gating zone and established it as a stable, non-turning-over component, refining where and how persistently it acts.","evidence":"BiFC interaction mapping with SSTR3 and AHI1 plus FRAP turnover analysis in a single lab","pmids":["28736169"],"confidence":"Medium","gaps":["Single study without replication","BiFC proximity does not establish stable direct binding","Functional consequence of SSTR3/AHI1 interaction not tested"]},{"year":2020,"claim":"Resolved the architecture of the B9D module as a linear MKS1-B9D2-B9D1 arrangement and showed the assembled complex—not individual subunits—is critical for the membrane diffusion barrier.","evidence":"MKS1-KO and B9D2-KO cell lines, rescue, Co-IP, immunofluorescence, and diffusion assays","pmids":["32726168"],"confidence":"High","gaps":["B9 proteins shown dispensable for, though involved in, ciliogenesis—threshold of requirement unclear","No high-resolution structure of the linear complex"]},{"year":2025,"claim":"Extended B9D1 function beyond gating to anchoring TMEM67 and regulating axonemal tubulin modifications, and to a pre-ciliogenesis centriolar role, broadening its mechanistic repertoire.","evidence":"Co-IP, knockout cell analysis, immunofluorescence, and posttranslational modification assays","pmids":["41165761"],"confidence":"Medium","gaps":["Single recent study not independently replicated","How the complex controls tubulin-modifying enzyme localization is undefined","Centriolar recruitment mechanism unknown"]},{"year":2025,"claim":"Showed B9D1 is excluded from the cilia precursor pool and requires new synthesis for transition zone assembly during regeneration, defining the source of B9D1 protein during ciliogenesis.","evidence":"Cycloheximide protein-synthesis blockade with live imaging and immunofluorescence in Xenopus multiciliated cells","pmids":["40087471"],"confidence":"Medium","gaps":["Single lab, single model organism","Transcriptional control of induced B9d1 not identified","Generalization to mammalian primary cilia untested"]},{"year":null,"claim":"How B9D1 mechanistically links to neurodevelopmental and serotonergic phenotypes, and the structural basis of barrier formation, remain open.","evidence":"No direct biochemical mechanism reported; the Ahi1/B9D1/Shh axis is defined only by rescue-based pathway placement","pmids":[],"confidence":"Low","gaps":["Biochemical mechanism downstream of B9D1 in serotonergic function not characterized","No structural model of how the assembled complex builds a diffusion barrier","Direct partner contacts inferred mostly from genetics/proximity assays"]}],"mechanism_profile":{"molecular_activity":[{"term_id":"GO:0060090","term_label":"molecular adaptor activity","supporting_discovery_ids":[10,0,6]}],"localization":[{"term_id":"GO:0005929","term_label":"cilium","supporting_discovery_ids":[0,1,3,5,6,7]},{"term_id":"GO:0005815","term_label":"microtubule organizing center","supporting_discovery_ids":[10,3]},{"term_id":"GO:0005829","term_label":"cytosol","supporting_discovery_ids":[5]}],"pathway":[{"term_id":"GO:0005929","term_label":"cilium","supporting_discovery_ids":[0,1,5]}],"complexes":["MKS complex (MKS1-B9D2-B9D1 module)","ciliary transition zone"],"partners":["B9D2","MKS1","TMEM231","CC2D2A","TMEM67","AHI1","SSTR3"],"other_free_text":[]}},"prefetch_data":{"uniprot":{"accession":"Q9UPM9","full_name":"B9 domain-containing protein 1","aliases":["MKS1-related protein 1"],"length_aa":204,"mass_kda":22.8,"function":"Component of the tectonic-like complex, a complex localized at the transition zone of primary cilia and acting as a barrier that prevents diffusion of transmembrane proteins between the cilia and plasma membranes. Required for ciliogenesis and sonic hedgehog/SHH signaling (By similarity)","subcellular_location":"Cytoplasm, cytoskeleton, cilium basal body; Cytoplasm, cytoskeleton, cilium axoneme","url":"https://www.uniprot.org/uniprotkb/Q9UPM9/entry"},"depmap":{"release":"DepMap","has_data":true,"is_common_essential":false,"resolved_as":"","url":"https://depmap.org/portal/gene/B9D1","classification":"Not Classified","n_dependent_lines":1,"n_total_lines":1208,"dependency_fraction":0.0008278145695364238},"opencell":{"profiled":false,"resolved_as":"","ensg_id":"","cell_line_id":"","localizations":[],"interactors":[],"url":"https://opencell.sf.czbiohub.org/search/B9D1","total_profiled":1310},"omim":[{"mim_id":"617121","title":"JOUBERT SYNDROME 28; JBTS28","url":"https://www.omim.org/entry/617121"},{"mim_id":"617120","title":"JOUBERT SYNDROME 27; JBTS27","url":"https://www.omim.org/entry/617120"},{"mim_id":"614950","title":"TRANSMEMBRANE PROTEIN 17; TMEM17","url":"https://www.omim.org/entry/614950"},{"mim_id":"614949","title":"TRANSMEMBRANE PROTEIN 231; TMEM231","url":"https://www.omim.org/entry/614949"},{"mim_id":"614209","title":"MECKEL SYNDROME, TYPE 9; MKS9","url":"https://www.omim.org/entry/614209"}],"hpa":{"profiled":true,"resolved_as":"","reliability":"Uncertain","locations":[{"location":"Nucleoplasm","reliability":"Uncertain"},{"location":"Acrosome","reliability":"Uncertain"},{"location":"Equatorial segment","reliability":"Uncertain"},{"location":"Mid piece","reliability":"Uncertain"},{"location":"Vesicles","reliability":"Additional"},{"location":"Basal body","reliability":"Additional"},{"location":"Cytosol","reliability":"Additional"},{"location":"Principal piece","reliability":"Additional"},{"location":"End piece","reliability":"Additional"}],"tissue_specificity":"Low tissue specificity","tissue_distribution":"Detected in all","driving_tissues":[],"url":"https://www.proteinatlas.org/search/B9D1"},"hgnc":{"alias_symbol":["B9","EPPB9","MKS9","MKSR-1"],"prev_symbol":[]},"alphafold":{"accession":"Q9UPM9","domains":[{"cath_id":"2.60.40.150","chopping":"8-180","consensus_level":"high","plddt":87.0025,"start":8,"end":180}],"viewer_url":"https://alphafold.ebi.ac.uk/entry/Q9UPM9","model_url":"https://alphafold.ebi.ac.uk/files/AF-Q9UPM9-F1-model_v6.cif","pae_url":"https://alphafold.ebi.ac.uk/files/AF-Q9UPM9-F1-predicted_aligned_error_v6.png","plddt_mean":82.69},"mouse_models":{"mgi_url":"https://www.informatics.jax.org/marker/summary?nomen=B9D1","jax_strain_url":"https://www.jax.org/strain/search?query=B9D1"},"sequence":{"accession":"Q9UPM9","fasta_url":"https://rest.uniprot.org/uniprotkb/Q9UPM9.fasta","uniprot_url":"https://www.uniprot.org/uniprotkb/Q9UPM9/entry","alphafold_viewer_url":"https://alphafold.ebi.ac.uk/entry/Q9UPM9"}},"corpus_meta":[{"pmid":"21725307","id":"PMC_21725307","title":"A transition zone 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Part A","url":"https://pubmed.ncbi.nlm.nih.gov/34338422","citation_count":13,"is_preprint":false},{"pmid":"33520453","id":"PMC_33520453","title":"High expression of MAPK-14 promoting the death of chondrocytes is an important signal of osteoarthritis process.","date":"2021","source":"PeerJ","url":"https://pubmed.ncbi.nlm.nih.gov/33520453","citation_count":11,"is_preprint":false},{"pmid":"21546380","id":"PMC_21546380","title":"Assessing the pathogenic potential of human Nephronophthisis disease-associated NPHP-4 missense mutations in C. elegans.","date":"2011","source":"Human molecular genetics","url":"https://pubmed.ncbi.nlm.nih.gov/21546380","citation_count":7,"is_preprint":false},{"pmid":"40087471","id":"PMC_40087471","title":"Mechanisms of cilia regeneration in Xenopus multiciliated epithelium in vivo.","date":"2025","source":"EMBO reports","url":"https://pubmed.ncbi.nlm.nih.gov/40087471","citation_count":7,"is_preprint":false},{"pmid":"32622957","id":"PMC_32622957","title":"Two novel B9D1 variants causing Joubert syndrome: Utility of mRNA and splicing studies.","date":"2020","source":"European journal of medical genetics","url":"https://pubmed.ncbi.nlm.nih.gov/32622957","citation_count":5,"is_preprint":false},{"pmid":"41165761","id":"PMC_41165761","title":"Ciliopathy-related B9 protein complex regulates ciliary axonemal microtubule posttranslational modifications and initiation of ciliogenesis.","date":"2025","source":"The Journal of clinical investigation","url":"https://pubmed.ncbi.nlm.nih.gov/41165761","citation_count":1,"is_preprint":false},{"pmid":"37398226","id":"PMC_37398226","title":"Mechanisms of cilia regeneration in Xenopus multiciliated epithelium in vivo.","date":"2024","source":"bioRxiv : the preprint server for biology","url":"https://pubmed.ncbi.nlm.nih.gov/37398226","citation_count":1,"is_preprint":false},{"pmid":"40565534","id":"PMC_40565534","title":"Investigating the Role of B9D1 in Meckel-Gruber Syndrome: A Case Report and Comprehensive Literature Review.","date":"2025","source":"Genes","url":"https://pubmed.ncbi.nlm.nih.gov/40565534","citation_count":0,"is_preprint":false},{"pmid":"40933483","id":"PMC_40933483","title":"Compound heterozygous missense and intronic variants in B9D1 contribute to a recurrent Meckel syndrome pedigree.","date":"2025","source":"Frontiers in genetics","url":"https://pubmed.ncbi.nlm.nih.gov/40933483","citation_count":0,"is_preprint":false},{"pmid":"41038357","id":"PMC_41038357","title":"Gestational diabetes mellitus induces 5-HT system dysfunction and exacerbates an ASD-like phenotype in male offspring by inhibiting the Ahi1/B9D1/Shh axis.","date":"2025","source":"Brain, behavior, and immunity","url":"https://pubmed.ncbi.nlm.nih.gov/41038357","citation_count":0,"is_preprint":false},{"pmid":"40820203","id":"PMC_40820203","title":"DNA methylation of food sensitization in a French-Canadian population.","date":"2025","source":"Clinical epigenetics","url":"https://pubmed.ncbi.nlm.nih.gov/40820203","citation_count":0,"is_preprint":false}],"cost":{"stage1":{"model":"claude-sonnet-4-6","input_tokens":16710,"output_tokens":3404,"usd":0.050595,"stage1_stop_reason":"end_turn"},"stage2":{"model":"claude-opus-4-8","input_tokens":10902,"output_tokens":3604,"usd":0.072305,"stage2_stop_reason":"end_turn"},"total_usd":0.1229,"stage1_batch_id":"msgbatch_0179Z2pxRYBsXi2xADneafRw","stage2_batch_id":"msgbatch_01LaY9ZaVdgjWArcZo9eqQE5","note":"batch pricing = 50% of standard"},"stage1_raw":"```json\n{\n  \"discoveries\": [\n    {\n      \"year\": 2011,\n      \"finding\": \"B9D1 is a component of a transition zone complex (with Mks1, Tmem216, Tmem67, Cep290, Tctn2, Cc2d2a, and Tctn1) that co-localizes at the ciliary transition zone and regulates ciliary assembly and trafficking of membrane-associated proteins including Arl13b, AC3, Smoothened, and Pkd2.\",\n      \"method\": \"Co-immunoprecipitation, immunofluorescence co-localization, mouse genetics (knockout)\",\n      \"journal\": \"Nature genetics\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — reciprocal Co-IP and co-localization, replicated across multiple labs and studies\",\n      \"pmids\": [\"21725307\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2011,\n      \"finding\": \"B9D1 localizes to the ciliary transition zone interdependently with TMEM231 and CC2D2A (and in a Sept2-regulated fashion); disruption of this complex reduces cilia formation, removes signaling receptors from cilia, and increases the rate of diffusion into the ciliary membrane, demonstrating that B9D1 is essential for maintaining the ciliary membrane as a diffusion barrier.\",\n      \"method\": \"RNAi knockdown, proteomics, mouse knockout, fluorescence recovery after photobleaching (FRAP), co-localization immunofluorescence\",\n      \"journal\": \"Nature cell biology\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — multiple orthogonal methods (RNAi, mouse KO, FRAP, proteomics), single rigorous study with functional readouts\",\n      \"pmids\": [\"22179047\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2011,\n      \"finding\": \"Mice lacking B9d1 display polydactyly, kidney cysts, ductal plate malformations, and abnormal neural tube patterning, with compromised ciliogenesis, ciliary protein localization, and Hedgehog signal transduction. Co-immunoprecipitation and mass spectrometry showed that Mks1, B9d1, and B9d2 physically interact as a complex.\",\n      \"method\": \"Mouse knockout (B9d1-null), co-immunoprecipitation, mass spectrometry, zebrafish rescue assay\",\n      \"journal\": \"American journal of human genetics\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — mouse KO with defined cellular phenotype plus Co-IP/MS protein interaction, replicated across studies\",\n      \"pmids\": [\"21763481\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2008,\n      \"finding\": \"The C. elegans B9D1 ortholog TZA-2 (MKSR-1) forms a complex with the other B9 proteins (XBX-7/MKS1 and TZA-1/B9D2) that localizes to the base of cilia (transition zone/basal body). Single B9 gene mutations do not overtly affect cilia, but combinations with nph-1 or nph-4 mutations cause ciliogenesis and dendrite formation defects, indicating functional redundancy between B9 proteins and nephrocystins.\",\n      \"method\": \"C. elegans genetics (single and double mutants), fluorescence microscopy localization\",\n      \"journal\": \"Molecular biology of the cell\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — genetic epistasis with defined phenotypic readout, replicated across multiple papers\",\n      \"pmids\": [\"18337471\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2009,\n      \"finding\": \"C. elegans MKSR-1 (B9D1 ortholog) and MKSR-2 (B9D2 ortholog) localize to transition zones/basal bodies of sensory cilia in a co-dependent manner with MKS-1. Disrupting human MKSR1 (B9D1) causes ciliogenesis defects. Genetic interactions between all double mks/mksr mutant combinations manifest as increased lifespan due to abnormal insulin-IGF-I signaling.\",\n      \"method\": \"C. elegans fluorescence microscopy, RNAi knockdown of human MKSR1, genetic epistasis analysis\",\n      \"journal\": \"Journal of cell science\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — multiple orthogonal methods (localization, human RNAi, C. elegans genetics), conserved findings across organisms\",\n      \"pmids\": [\"19208769\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2020,\n      \"finding\": \"The B9D protein complex interaction mode is MKS1-B9D2-B9D1 (not a simple trimeric hub), with interdependent localization to the transition zone. MKS1-KO and B9D2-KO cells show that B9D proteins are involved in, though not essential for, cilia biogenesis, but formation of the full B9D complex is crucial for establishing a diffusion barrier for ciliary membrane proteins.\",\n      \"method\": \"Knockout cell lines (MKS1-KO, B9D2-KO), rescue experiments, co-immunoprecipitation, immunofluorescence, diffusion assay\",\n      \"journal\": \"Molecular biology of the cell\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — KO cell lines with rescue, Co-IP defining interaction mode, functional diffusion barrier assay — multiple orthogonal methods in one study\",\n      \"pmids\": [\"32726168\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2015,\n      \"finding\": \"Tmem231 and B9d1 are mutually required for each other's localization to the transition zone, and both are required for other MKS complex components such as Mks1 to localize to the transition zone. Loss of Tmem231 or B9d1 disrupts localization of ciliary proteins including Arl13b and Inpp5e, causing MKS-like phenotypes.\",\n      \"method\": \"Mouse knockout, immunofluorescence co-localization\",\n      \"journal\": \"The Journal of cell biology\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — mouse KO with defined phenotype and mutual dependency of localization demonstrated, replicated across labs\",\n      \"pmids\": [\"25869670\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2017,\n      \"finding\": \"Using BiFC (bimolecular fluorescence complementation) assay, B9D1 and AHI1 interact with the transmembrane protein SSTR3, spatially mapping to the outer region of the ciliary gating zone. B9D1 exhibits little to no turnover at the transition zone (stable component), as shown by FRAP analysis.\",\n      \"method\": \"BiFC assay, FRAP (fluorescence recovery after photobleaching)\",\n      \"journal\": \"Current biology : CB\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Weak — novel BiFC mapping and FRAP in a single lab, single study; no replication\",\n      \"pmids\": [\"28736169\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2015,\n      \"finding\": \"Blocking TGF-β/Smad2 signaling in Xenopus results in the absence of B9D1/MKSR-1 from cilia in multi-ciliated cells, indicating that TGF-β signaling controls B9D1 localization to the transition zone and is required for normal transition zone function.\",\n      \"method\": \"Xenopus in vivo signaling blockade (dominant-negative Smad2), immunofluorescence\",\n      \"journal\": \"Cell reports\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Weak — defined upstream regulator of B9D1 localization, single lab, single model organism study\",\n      \"pmids\": [\"25959824\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2011,\n      \"finding\": \"In C. elegans, JBTS-14/TMEM237 functionally interacts with MKSR-1/B9D1 and MKSR-2/B9D2 to control basal body-transition zone anchoring to the membrane and ciliogenesis, placing B9D1 in a genetic interaction network with TMEM237 and RPGRIP1L/MKS5.\",\n      \"method\": \"C. elegans genetic epistasis, fluorescence microscopy\",\n      \"journal\": \"American journal of human genetics\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — genetic epistasis with defined phenotype in C. elegans, orthogonal to other localization studies\",\n      \"pmids\": [\"22152675\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2025,\n      \"finding\": \"The B9D1-B9D2-MKS1 complex interacts with and anchors TMEM67 to the transition zone membrane; disruption of this complex reduces posttranslational modifications of axonemal microtubules by deregulating tubulin-modifying enzymes within cilia. Additionally, B9D1 localizes to centrioles prior to ciliogenesis, where it facilitates the initiation of ciliogenesis.\",\n      \"method\": \"Co-immunoprecipitation, knockout cell analysis, immunofluorescence, posttranslational modification assays\",\n      \"journal\": \"The Journal of clinical investigation\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Weak — multiple functional readouts in a single recent study, not yet independently replicated\",\n      \"pmids\": [\"41165761\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2025,\n      \"finding\": \"In Xenopus multiciliated cells, B9d1 is not present in the cilia precursor pool; cycloheximide treatment blocking protein synthesis prevents B9d1 from appearing at regenerating transition zones, demonstrating that B9d1 requires new transcription/translation for transition zone assembly during cilia regeneration.\",\n      \"method\": \"Cycloheximide protein synthesis blockade, live imaging, immunofluorescence in Xenopus MCCs\",\n      \"journal\": \"EMBO reports\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Weak — direct experimental evidence for B9d1 not being in precursor pool, single lab, single study, preprint version also available\",\n      \"pmids\": [\"40087471\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2012,\n      \"finding\": \"In C. elegans, mksr-1 (B9D1 ortholog) genetically interacts with nphp-2 (inversin) in a sensilla-dependent manner to control cilia formation and placement, placing B9D1 in the MKS genetic pathway that modifies NPHP pathway function.\",\n      \"method\": \"C. elegans genetic epistasis (double mutants), fluorescence microscopy\",\n      \"journal\": \"Journal of cell science\",\n      \"confidence\": \"Low\",\n      \"confidence_rationale\": \"Tier 3 / Weak — C. elegans genetic interaction, single lab, no mechanistic molecular detail beyond pathway placement\",\n      \"pmids\": [\"22393243\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2025,\n      \"finding\": \"Ahi1 knockdown in mouse dorsal raphe nucleus reduces B9D1 levels; overexpression of B9D1 rescues ASD-like behaviors and 5-HT system dysfunction caused by Ahi1 knockdown or GDM exposure, placing B9D1 downstream of Ahi1 in an Ahi1/B9D1/Shh axis that regulates serotonergic function.\",\n      \"method\": \"AAV-mediated Ahi1 knockdown in mouse brain, B9D1 overexpression rescue, behavioral assays, in vitro LPS neuroinflammation model\",\n      \"journal\": \"Brain, behavior, and immunity\",\n      \"confidence\": \"Low\",\n      \"confidence_rationale\": \"Tier 3 / Weak — single lab, pathway placement by rescue experiment, mechanism downstream of Ahi1 not directly biochemically characterized in this abstract\",\n      \"pmids\": [\"41038357\"],\n      \"is_preprint\": false\n    }\n  ],\n  \"current_model\": \"B9D1 is a stable, soluble transition zone protein that forms a tripartite complex with B9D2 and MKS1 (in the order MKS1-B9D2-B9D1), localizes to the outer region of the ciliary gating zone in a manner interdependent with TMEM231 and CC2D2A, anchors TMEM67 to the transition zone membrane, acts as a diffusion barrier to maintain ciliary membrane compartmentalization, facilitates the initiation of ciliogenesis at centrioles, and regulates posttranslational modifications of axonemal microtubules; loss of B9D1 compromises Hedgehog signaling, ciliogenesis, and ciliary protein localization, causing ciliopathies including Meckel syndrome and Joubert syndrome.\"\n}\n```","stage2_raw":"{\n  \"mechanistic_narrative\": \"B9D1 is a stable, soluble transition zone protein that controls the ciliary gating apparatus by forming a defined module of the Meckel syndrome (MKS) complex and enforcing the diffusion barrier that compartmentalizes the ciliary membrane [#0, #1]. It assembles into a tripartite unit with B9D2 and MKS1 in the linear arrangement MKS1-B9D2-B9D1 rather than a simple trimeric hub, and formation of the full complex is required to establish a diffusion barrier for ciliary membrane proteins [#5, #2]. B9D1 localizes to the transition zone interdependently with TMEM231 and CC2D2A, and this mutual dependency is needed to recruit other MKS components such as MKS1 and to retain ciliary signaling proteins including ARL13B, INPP5E, Smoothened, and PKD2; loss of B9D1 increases the diffusion rate into the ciliary membrane, depletes signaling receptors from cilia, and compromises Hedgehog signal transduction [#0, #1, #6]. Within this module B9D1 anchors TMEM67 to the transition zone membrane and constrains tubulin-modifying enzymes so that loss of the complex deregulates posttranslational modification of axonemal microtubules; B9D1 also localizes to centrioles before ciliogenesis to facilitate its initiation [#10]. As a stable, low-turnover transition zone component spatially mapped to the outer ciliary gating zone, it interacts with SSTR3 and AHI1 [#7]. B9D1 is a ciliopathy gene whose loss in mice produces polydactyly, kidney cysts, ductal plate malformations, and abnormal neural tube patterning, recapitulating Meckel syndrome-like and Joubert syndrome phenotypes [#2].\",\n  \"teleology\": [\n    {\n      \"year\": 2008,\n      \"claim\": \"Established that the B9D1 ortholog is not an isolated protein but a member of a conserved B9-protein module at the ciliary base, answering whether B9 proteins function together.\",\n      \"evidence\": \"C. elegans single/double mutant genetics and fluorescence localization of TZA-2/MKSR-1 with XBX-7/MKS1 and TZA-1/B9D2\",\n      \"pmids\": [\"18337471\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Single B9 mutations cause no overt cilia defect, leaving the non-redundant role unclear\", \"No molecular architecture of the complex\", \"Redundancy with nephrocystins not resolved mechanistically\"]\n    },\n    {\n      \"year\": 2009,\n      \"claim\": \"Showed the co-dependence of B9 proteins for transition zone localization is conserved and that the human ortholog is required for ciliogenesis, linking worm genetics to human cilia biology.\",\n      \"evidence\": \"C. elegans co-localization of MKSR-1/MKSR-2 with MKS-1, RNAi of human MKSR1, and genetic epistasis affecting insulin-IGF-I signaling/lifespan\",\n      \"pmids\": [\"19208769\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Biochemical basis of co-dependent localization not defined\", \"Direct human protein interactions not shown\"]\n    },\n    {\n      \"year\": 2011,\n      \"claim\": \"Defined B9D1 as part of a multi-subunit transition zone complex that gates ciliary membrane protein trafficking, establishing its role in maintaining the ciliary diffusion barrier.\",\n      \"evidence\": \"Reciprocal Co-IP, immunofluorescence, mouse knockouts, FRAP, and proteomics across multiple studies showing interdependent localization with TMEM231/CC2D2A and mislocalization of Arl13b, Smoothened, AC3, and Pkd2\",\n      \"pmids\": [\"21725307\", \"22179047\", \"21763481\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Stoichiometry and interaction topology within the complex unresolved\", \"Mechanism by which the barrier is physically established not defined\"]\n    },\n    {\n      \"year\": 2011,\n      \"claim\": \"Placed B9D1 in a broader genetic interaction network controlling basal body-transition zone membrane anchoring, connecting the B9 module to TMEM237 and RPGRIP1L/MKS5.\",\n      \"evidence\": \"C. elegans genetic epistasis and fluorescence microscopy of JBTS-14/TMEM237 with MKSR-1/MKSR-2\",\n      \"pmids\": [\"22152675\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Genetic interaction does not establish direct physical contact\", \"Conservation of the anchoring mechanism in mammals not tested here\"]\n    },\n    {\n      \"year\": 2012,\n      \"claim\": \"Positioned B9D1 within the MKS pathway as a modifier of NPHP pathway function in cilia formation and placement.\",\n      \"evidence\": \"C. elegans double-mutant epistasis of mksr-1 with nphp-2/inversin\",\n      \"pmids\": [\"22393243\"],\n      \"confidence\": \"Low\",\n      \"gaps\": [\"No molecular mechanism beyond pathway placement\", \"Sensilla-dependence not mechanistically explained\", \"Not validated in mammalian cells\"]\n    },\n    {\n      \"year\": 2015,\n      \"claim\": \"Demonstrated mutual localization dependency between B9D1 and TMEM231 and identified upstream control of B9D1 transition zone targeting, clarifying how the gating module is built and regulated.\",\n      \"evidence\": \"Mouse knockouts with immunofluorescence (TMEM231/B9D1 interdependency, Arl13b/Inpp5e mislocalization) and Xenopus TGF-β/Smad2 signaling blockade affecting B9D1 ciliary localization\",\n      \"pmids\": [\"25869670\", \"25959824\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"How TGF-β/Smad2 signaling mechanistically directs B9D1 localization is unknown\", \"Direct versus indirect TMEM231-B9D1 contact not biochemically resolved\"]\n    },\n    {\n      \"year\": 2017,\n      \"claim\": \"Spatially mapped B9D1 to the outer region of the ciliary gating zone and established it as a stable, non-turning-over component, refining where and how persistently it acts.\",\n      \"evidence\": \"BiFC interaction mapping with SSTR3 and AHI1 plus FRAP turnover analysis in a single lab\",\n      \"pmids\": [\"28736169\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Single study without replication\", \"BiFC proximity does not establish stable direct binding\", \"Functional consequence of SSTR3/AHI1 interaction not tested\"]\n    },\n    {\n      \"year\": 2020,\n      \"claim\": \"Resolved the architecture of the B9D module as a linear MKS1-B9D2-B9D1 arrangement and showed the assembled complex—not individual subunits—is critical for the membrane diffusion barrier.\",\n      \"evidence\": \"MKS1-KO and B9D2-KO cell lines, rescue, Co-IP, immunofluorescence, and diffusion assays\",\n      \"pmids\": [\"32726168\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"B9 proteins shown dispensable for, though involved in, ciliogenesis—threshold of requirement unclear\", \"No high-resolution structure of the linear complex\"]\n    },\n    {\n      \"year\": 2025,\n      \"claim\": \"Extended B9D1 function beyond gating to anchoring TMEM67 and regulating axonemal tubulin modifications, and to a pre-ciliogenesis centriolar role, broadening its mechanistic repertoire.\",\n      \"evidence\": \"Co-IP, knockout cell analysis, immunofluorescence, and posttranslational modification assays\",\n      \"pmids\": [\"41165761\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Single recent study not independently replicated\", \"How the complex controls tubulin-modifying enzyme localization is undefined\", \"Centriolar recruitment mechanism unknown\"]\n    },\n    {\n      \"year\": 2025,\n      \"claim\": \"Showed B9D1 is excluded from the cilia precursor pool and requires new synthesis for transition zone assembly during regeneration, defining the source of B9D1 protein during ciliogenesis.\",\n      \"evidence\": \"Cycloheximide protein-synthesis blockade with live imaging and immunofluorescence in Xenopus multiciliated cells\",\n      \"pmids\": [\"40087471\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Single lab, single model organism\", \"Transcriptional control of induced B9d1 not identified\", \"Generalization to mammalian primary cilia untested\"]\n    },\n    {\n      \"year\": null,\n      \"claim\": \"How B9D1 mechanistically links to neurodevelopmental and serotonergic phenotypes, and the structural basis of barrier formation, remain open.\",\n      \"evidence\": \"No direct biochemical mechanism reported; the Ahi1/B9D1/Shh axis is defined only by rescue-based pathway placement\",\n      \"pmids\": [],\n      \"confidence\": \"Low\",\n      \"gaps\": [\"Biochemical mechanism downstream of B9D1 in serotonergic function not characterized\", \"No structural model of how the assembled complex builds a diffusion barrier\", \"Direct partner contacts inferred mostly from genetics/proximity assays\"]\n    }\n  ],\n  \"mechanism_profile\": {\n    \"molecular_activity\": [\n      {\"term_id\": \"GO:0060090\", \"supporting_discovery_ids\": [10, 0, 6]}\n    ],\n    \"localization\": [\n      {\"term_id\": \"GO:0005929\", \"supporting_discovery_ids\": [0, 1, 3, 5, 6, 7]},\n      {\"term_id\": \"GO:0005815\", \"supporting_discovery_ids\": [10, 3]},\n      {\"term_id\": \"GO:0005829\", \"supporting_discovery_ids\": [5]}\n    ],\n    \"pathway\": [\n      {\"term_id\": \"GO:0005929\", \"supporting_discovery_ids\": [0, 1, 5]}\n    ],\n    \"complexes\": [\"MKS complex (MKS1-B9D2-B9D1 module)\", \"ciliary transition zone\"],\n    \"partners\": [\"B9D2\", \"MKS1\", \"TMEM231\", \"CC2D2A\", \"TMEM67\", \"AHI1\", \"SSTR3\"],\n    \"other_free_text\": []\n  }\n}","audit_flag":null,"evaluation":{"pairwise":"win","faith_supported":6,"faith_total":6,"faith_pct":100.0}}