{"gene":"MESP2","run_date":"2026-04-28T18:30:28","timeline":{"discoveries":[{"year":1997,"finding":"Mesp2 is a bHLH transcription factor expressed in the rostral presomitic mesoderm that is essential for segmentation initiation; Mesp2-null mice lack segmented somites and show altered expression of Mox-1, Pax-1, Dll1, Notch1, Notch2, and FGFR1, indicating Mesp2 controls sclerotomal polarity by regulating Notch-delta and FGF signaling pathways.","method":"Gene targeting (knockout mouse), in situ hybridization, immunohistochemistry","journal":"Genes & development","confidence":"High","confidence_rationale":"Tier 2 — clean KO with defined cellular phenotype, replicated in subsequent studies","pmids":["9242490"],"is_preprint":false},{"year":1998,"finding":"MesP1 can functionally substitute for MesP2 in somitogenesis in a dosage-dependent manner, and both proteins act via Notch-delta and FGF signaling systems, as shown by knock-in of Mesp1 cDNA into the Mesp2 locus rescuing skeletal defects and restoring Notch1, Notch2, and FGFR-1 expression.","method":"Gene knock-in (Mesp1 cDNA into Mesp2 locus), skeletal analysis, in situ hybridization","journal":"Mechanisms of development","confidence":"High","confidence_rationale":"Tier 2 — genetic epistasis/rescue experiment with defined molecular readouts","pmids":["9739106"],"is_preprint":false},{"year":2000,"finding":"MesP1 and MesP2 are essential for cardiac and paraxial mesoderm formation; double-knockout embryos lack mesodermal layer due to defective migratory activity of mesodermal cells, and chimera analysis showed the cardiac mesoderm defect is cell-autonomous while the paraxial mesoderm defect is non-cell-autonomous.","method":"Double knockout mouse, chimera analysis, molecular marker analysis","journal":"Development (Cambridge, England)","confidence":"High","confidence_rationale":"Tier 2 — genetic KO with chimera analysis providing cell-autonomy distinction","pmids":["10887078"],"is_preprint":false},{"year":2000,"finding":"Mesp2 initiates rostro-caudal polarity by controlling two Notch signaling pathways: it activates a presenilin-1 (Ps1)-independent Notch cascade to suppress Dll1 expression and specify the rostral somite half, while Ps1-mediated Notch signaling induces Dll1 in the caudal half.","method":"Genetic epistasis analysis (Mesp2, Ps1, Dll1 mutant combinations), in situ hybridization","journal":"Nature genetics","confidence":"High","confidence_rationale":"Tier 2 — genetic epistasis with multiple mutant combinations, replicated in subsequent studies","pmids":["10932180"],"is_preprint":false},{"year":2001,"finding":"Mesp2 expression is controlled by at least two distinct enhancers: an early mesodermal enhancer (EME) and a presomitic mesoderm enhancer (PSME), with a separate suppressor element restricting expression to the rostral PSM.","method":"Transient transgenic analysis, enhancer deletion studies","journal":"Mechanisms of development","confidence":"Medium","confidence_rationale":"Tier 2 — in vivo transgenic enhancer mapping, single lab","pmids":["11578861"],"is_preprint":false},{"year":2003,"finding":"Positive and negative feedback loops comprising Dll1 and Mesp2 are crucial for rostrocaudal patterning; Mesp2 affects rostrocaudal properties more directly than Dll1 or Dll3, and Psen1 is differentially required for Dll1-Notch signaling activation of Dll1 but not for the Dll3-Notch pathway that counteracts it.","method":"Genetic epistasis analysis using Dll1, Dll3, Mesp2, and Psen1 mutant combinations","journal":"Development (Cambridge, England)","confidence":"High","confidence_rationale":"Tier 2 — multiple genetic epistasis combinations, replicated finding","pmids":["12900443"],"is_preprint":false},{"year":2005,"finding":"Mesp2 suppresses Notch activity in the anterior PSM through induction of the lunatic fringe gene (Lfng), thereby establishing segmental borders at the interface between Notch1-activated and Notch1-repressed domains; this was demonstrated by genetic and biochemical studies including visualization of endogenous Notch1 activity oscillation.","method":"Knock-in reporter mice for Notch1 activity visualization, genetic epistasis, biochemical assays","journal":"Nature","confidence":"High","confidence_rationale":"Tier 1–2 — multiple orthogonal methods (in vivo reporter, genetics, biochemistry) in a high-impact study","pmids":["15902259"],"is_preprint":false},{"year":2005,"finding":"Mesp2 and Mesp1 have distinct roles in somitogenesis: Mesp2 is essential for segment border formation and rostral identity (cell-autonomously), while Mesp1 plays a greater role in epithelialization of somitic mesoderm; chimera analyses showed Mesp mutant cells exert non-cell-autonomous effects on normal cell somite formation.","method":"Chimera analysis with Mesp2-null and Mesp1/Mesp2 double-null cells","journal":"Development (Cambridge, England)","confidence":"High","confidence_rationale":"Tier 2 — chimera analysis providing cell-autonomy dissection with multiple genotypes","pmids":["15677726"],"is_preprint":false},{"year":2006,"finding":"Tbx6 directly binds to the Mesp2 upstream enhancer region and mediates Notch signaling to activate Mesp2 transcription in the anterior presomitic mesoderm.","method":"ChIP, reporter assays in cultured cells, Tbx6-null mouse analysis, in situ hybridization","journal":"Proceedings of the National Academy of Sciences of the United States of America","confidence":"High","confidence_rationale":"Tier 2 — ChIP confirming direct binding, supported by genetic evidence in Tbx6-null mice","pmids":["16505380"],"is_preprint":false},{"year":2006,"finding":"Mesp2 directly binds to an E-box-containing enhancer of Epha4 and activates its expression in the anterior PSM; forced expression of Mesp2 in somitic cells activates Epha4 and represses the caudal gene Uncx4.1, and induces abnormal epithelialized structures consistent with Mesp2 driving segmental border formation via cellular epithelialization genes.","method":"Transgenic reporter analysis, transient luciferase assay, ChIP/direct binding, gain-of-function Mesp2 misexpression","journal":"Development (Cambridge, England)","confidence":"High","confidence_rationale":"Tier 1–2 — direct binding to enhancer confirmed plus functional gain-of-function phenotype","pmids":["16728472"],"is_preprint":false},{"year":2007,"finding":"Mesp2 directly binds the Ripply2 gene enhancer and activates its transcription; Ripply2 (a WRPW-motif co-repressor) in turn negatively regulates Mesp2 in a feedback loop, so that loss of Ripply2 causes prolonged Mesp2 expression leading to rostralized somites via suppression of Notch signaling.","method":"Microarray, enhancer binding assay (ChIP/gel shift), Ripply2 knockout mouse, genetic epistasis","journal":"Development (Cambridge, England)","confidence":"High","confidence_rationale":"Tier 2 — direct binding confirmed, KO phenotype analyzed, feedback loop genetically validated","pmids":["17360776"],"is_preprint":false},{"year":2007,"finding":"Mesp2 and Paraxis genetically interact in sclerotomal development; Mesp2/Paraxis double-null mice show severe reduction of vertebral body and neural arch components. Pax3 expression in the anteriormost PSM is regulated by both Mesp2 and Paraxis. Yeast two-hybrid analyses showed no direct protein-protein interaction between Mesp2 and Paraxis, indicating the interaction is indirect.","method":"Double knockout mouse, yeast two-hybrid, in situ hybridization","journal":"Developmental dynamics","confidence":"Medium","confidence_rationale":"Tier 2 — genetic double KO with defined phenotype and negative protein interaction test, single lab","pmids":["17477400"],"is_preprint":false},{"year":2008,"finding":"Mesp2 transcription is periodically activated by waves of Notch activity and spatially defined by Tbx6 protein. Once translated, Mesp2 protein induces rapid post-translational degradation of Tbx6 protein via the ubiquitin-proteasome pathway, thereby defining the anterior border of Mesp2 expression and translating clock periodicity into spatial segmental patterning.","method":"High-resolution fluorescent in situ hybridization, immunohistochemistry, proteasome inhibitor treatment","journal":"Development (Cambridge, England)","confidence":"High","confidence_rationale":"Tier 2 — multiple orthogonal methods demonstrating post-translational mechanism with pharmacological validation","pmids":["18579680"],"is_preprint":false},{"year":2008,"finding":"Two evolutionarily conserved Tbx6 binding sites in the Mesp2 PSM-specific enhancer are indispensable in vivo for Mesp2 expression; enhancer knockout mice bearing mutations in these sites show absent Mesp2 PSM expression and skeletal segmentation defects identical to Mesp2-null mice.","method":"Enhancer knockout mouse, ChIP, transgenic reporter analysis","journal":"Development (Cambridge, England)","confidence":"High","confidence_rationale":"Tier 2 — in vivo enhancer mutagenesis confirmed by ChIP and phenocopy of null mouse","pmids":["18849530"],"is_preprint":false},{"year":2010,"finding":"Mesp2 suppresses Notch signaling by inducing destabilization of mastermind-like 1 (MAML1), a core Notch transcriptional co-activator; this function is independent of Mesp2's role as a transcription factor, as shown by a dominant-negative Rbpj knock-in into the Mesp2 locus almost completely rescuing Mesp2-null segmental defects.","method":"Knock-in mouse (dominant-negative Rbpj into Mesp2 locus), biochemical co-immunoprecipitation and protein stability assays, genetic rescue","journal":"Development (Cambridge, England)","confidence":"High","confidence_rationale":"Tier 1–2 — genetic rescue combined with biochemical evidence of MAML1 destabilization, multiple orthogonal approaches","pmids":["21098559"],"is_preprint":false},{"year":2015,"finding":"Ripply2 represses Tbx6 protein post-translationally in a Mesp2-independent manner to establish the segmental border; Ripply2 knock-in into the Mesp2 locus can generate the anterior Tbx6 domain limit even without Mesp2, and ectopic Ripply2 suppresses Tbx6 protein (not mRNA), demonstrating post-translational Tbx6 regulation.","method":"Transgenic overexpression, Ripply2 knock-in into Mesp2 locus, ectopic expression in PSM, protein/mRNA analysis","journal":"Developmental biology","confidence":"High","confidence_rationale":"Tier 2 — multiple transgenic approaches distinguishing protein vs. mRNA level regulation","pmids":["25641698"],"is_preprint":false},{"year":2020,"finding":"MESP2 directly regulates transcriptional activities of downstream genes MYOCD, GATA4, NKX2.5, and CFC1, and promotes cardiac neural crest cell (CNCC) proliferation by regulating cell cycle factors p21cip1 and Cdk4; MESP2 variants found in conotruncal heart defect patients inhibit CNCC proliferation.","method":"Luciferase reporter assays, primary mouse CNCC cultures, cell cycle analysis, variant functional analysis in HEK293T and JoMa1 cells","journal":"Journal of molecular medicine","confidence":"Medium","confidence_rationale":"Tier 2–3 — functional assays in cultured cells with patient variants, single lab","pmids":["32572506"],"is_preprint":false},{"year":2021,"finding":"MESP1 and MESP2 expression in the early mesoderm is regulated by the cooperation of two independent enhancers containing T-box- and TCF/Lef-binding sites; deletion of both enhancers causes downregulation of both genes and heart formation defects, and upregulation of Mesp2 in Mesp1 KO embryos compensates for Mesp1 loss in mesoderm specification.","method":"Genome-editing KO without selection markers, enhancer deletion analysis, RT-PCR","journal":"Development (Cambridge, England)","confidence":"Medium","confidence_rationale":"Tier 2 — clean CRISPR KO and enhancer deletion with phenotypic readout, single lab","pmids":["34679163"],"is_preprint":false},{"year":2022,"finding":"Upon loss of Mesp2, the Mesp2 enhancer directly interacts with the Mesp1 promoter via genomic looping established during PSM development, thereby upregulating Mesp1 as a compensatory mechanism; this enhancer-promoter communication is established by genomic arrangement independently of Mesp2 disruption.","method":"Cultured PSM induction system, chromatin conformation assays, transgenic reporter analysis","journal":"PLoS genetics","confidence":"Medium","confidence_rationale":"Tier 2 — in vitro PSM system combined with chromatin conformation data, single lab","pmids":["35025872"],"is_preprint":false},{"year":2023,"finding":"MESP2 binds to TCF7L2/TCF4 and inhibits activation of the TCF4/β-catenin transcriptional complex, reducing its occupancy on the SKP2 promoter and thereby promoting p27 accumulation to suppress gastric cancer cell growth and invasion.","method":"Co-immunoprecipitation, ChIP, luciferase reporter assays, in vitro and in vivo overexpression/knockdown","journal":"Cell death discovery","confidence":"Medium","confidence_rationale":"Tier 2–3 — Co-IP and ChIP supporting direct interaction, functional rescue by SKP2 KD, single lab","pmids":["36854722"],"is_preprint":false}],"current_model":"MESP2 is a bHLH transcription factor expressed in the anterior presomitic mesoderm that acts as a central regulator of vertebrate somitogenesis by: (1) directly binding E-box enhancers to activate target genes (Epha4, Lfng, Ripply2) and suppress Notch signaling both transcriptionally (via Lfng induction) and post-translationally (by inducing MAML1 destabilization independently of its transcription factor function); (2) inducing post-translational degradation of Tbx6 via the ubiquitin-proteasome pathway to spatially define the segmental border; (3) being transcriptionally activated itself by Tbx6 binding to conserved T-box sites in its PSM-specific enhancer downstream of Notch signaling; and (4) participating in a negative feedback loop with Ripply2 to ensure periodically restricted Mesp2 expression, thereby translating the temporal segmentation clock signal into spatial rostro-caudal somite patterning."},"narrative":{"teleology":[{"year":1997,"claim":"Establishing that MESP2 is essential for somite segmentation resolved the question of which transcription factor initiates rostro-caudal patterning in the presomitic mesoderm.","evidence":"Mesp2-null mice lack segmented somites and show disrupted Notch, Dll1, and FGF pathway gene expression","pmids":["9242490"],"confidence":"High","gaps":["Mechanism by which MESP2 controls Notch/Dll1 expression was unknown","Direct transcriptional targets not identified","Whether MESP2 acts cell-autonomously was untested"]},{"year":1998,"claim":"Demonstrating that MESP1 knock-in into the Mesp2 locus rescues segmentation established functional redundancy between the two paralogs and confirmed that MESP2's role in somitogenesis operates through shared downstream pathways.","evidence":"Mesp1 cDNA knock-in into Mesp2 locus restores Notch1/2 and FGFR1 expression and rescues skeletal defects dose-dependently","pmids":["9739106"],"confidence":"High","gaps":["The basis for unique versus shared MESP1/MESP2 functions was unresolved","Direct DNA targets of either factor not yet identified"]},{"year":2000,"claim":"Genetic epistasis with Presenilin-1 and Dll1 mutants revealed that MESP2 establishes rostral somite identity by activating a Presenilin-independent Notch pathway that suppresses Dll1, while Presenilin-mediated Notch signaling drives caudal identity — resolving how one transcription factor generates opposing compartment fates.","evidence":"Compound mutant analysis of Mesp2, Ps1, and Dll1; in situ hybridization for compartment markers","pmids":["10932180"],"confidence":"High","gaps":["Identity of the Presenilin-independent Notch pathway component was unknown","Whether MESP2 directly acts on Dll1 enhancer or acts indirectly was unresolved"]},{"year":2005,"claim":"Identification of Lunatic fringe (Lfng) as the Mesp2-induced suppressor of Notch activity provided the molecular mechanism by which MESP2 creates the segmental border at the interface of Notch-active and Notch-repressed domains.","evidence":"Knock-in Notch1 activity reporters, genetic epistasis, and biochemical assays in mouse embryos","pmids":["15902259"],"confidence":"High","gaps":["Whether MESP2 directly binds the Lfng enhancer was not shown","Non-transcriptional mechanisms of Notch suppression by MESP2 were not yet discovered"]},{"year":2006,"claim":"ChIP-based demonstration that Tbx6 directly binds the Mesp2 upstream enhancer, and that this binding mediates Notch-dependent Mesp2 activation, established the input logic gating MESP2 transcription in the anterior PSM.","evidence":"ChIP in cultured cells, reporter assays, analysis in Tbx6-null mice","pmids":["16505380","18849530"],"confidence":"High","gaps":["How Notch signaling cooperates with Tbx6 at the enhancer at the chromatin level was unresolved","Periodicity mechanism linking the clock to Tbx6/Mesp2 activation was not fully explained"]},{"year":2006,"claim":"Direct binding of MESP2 to the Epha4 E-box enhancer and gain-of-function induction of epithelialization genes identified the first confirmed direct transcriptional target and linked MESP2 to the cellular mechanics of border formation.","evidence":"ChIP/direct binding assay, transgenic reporter, luciferase assay, Mesp2 misexpression in somitic cells","pmids":["16728472"],"confidence":"High","gaps":["Full repertoire of direct MESP2 transcriptional targets remained incomplete","How Epha4 activation translates to epithelialization was unexplored"]},{"year":2007,"claim":"Discovery that MESP2 directly activates Ripply2, which then feeds back to terminate MESP2 expression, explained how MESP2 expression is temporally restricted to a single somite-forming unit.","evidence":"Microarray, ChIP/gel shift for direct Ripply2 enhancer binding, Ripply2 KO mouse with rostralized somite phenotype","pmids":["17360776"],"confidence":"High","gaps":["Mechanism by which Ripply2 represses Mesp2 (direct or indirect, transcriptional or post-translational) was unclear","Whether Ripply2 feeds back on Tbx6 independently of MESP2 was unknown"]},{"year":2008,"claim":"Demonstrating that MESP2 induces ubiquitin-proteasome-mediated degradation of Tbx6 protein provided the key mechanism by which MESP2 sharpens its own expression boundary and converts temporal clock periodicity into a spatial segment.","evidence":"High-resolution FISH, immunohistochemistry, proteasome inhibitor treatment in mouse embryos","pmids":["18579680"],"confidence":"High","gaps":["The E3 ubiquitin ligase responsible for Tbx6 degradation was not identified","Whether MESP2 directly participates in the Tbx6 degradation complex or acts indirectly was unresolved"]},{"year":2010,"claim":"Revealing that MESP2 destabilizes MAML1 to suppress Notch signaling independently of its DNA-binding/transcription factor function uncovered a dual-mode mechanism — transcriptional (via Lfng) and post-translational (via MAML1) — for Notch suppression by a single bHLH factor.","evidence":"Dominant-negative Rbpj knock-in into Mesp2 locus rescuing segmental defects; Co-IP and protein stability assays for MAML1","pmids":["21098559"],"confidence":"High","gaps":["The domain of MESP2 responsible for MAML1 destabilization was not mapped","Whether MESP2 directly binds MAML1 or requires an adaptor was not resolved"]},{"year":2015,"claim":"Ripply2 knock-in into the Mesp2 locus demonstrated that Ripply2 can independently suppress Tbx6 protein post-translationally, refining the segmental border model by showing that MESP2 is not the sole regulator of Tbx6 degradation.","evidence":"Ripply2 knock-in into Mesp2 locus, ectopic Ripply2 expression in PSM, protein versus mRNA analysis","pmids":["25641698"],"confidence":"High","gaps":["The relative contributions of MESP2 versus Ripply2 to Tbx6 degradation in normal development were not quantified"]},{"year":2020,"claim":"Functional analysis of MESP2 in cardiac neural crest cells expanded its known roles beyond somitogenesis, showing it regulates proliferation via p21/Cdk4 and activates cardiac transcription factors, with patient variants linked to conotruncal heart defects.","evidence":"Luciferase reporter assays, primary mouse CNCC cultures, cell cycle analysis, patient variant functional tests in HEK293T/JoMa1 cells","pmids":["32572506"],"confidence":"Medium","gaps":["In vivo cardiac phenotype of MESP2 loss-of-function specifically in neural crest was not demonstrated","Whether these cardiac functions are bHLH DNA-binding dependent or involve the MAML1 destabilization mode was untested"]},{"year":2022,"claim":"Chromatin conformation studies revealed that the Mesp2 enhancer can loop to activate the Mesp1 promoter upon Mesp2 loss, explaining the compensatory upregulation of Mesp1 and the locus-level regulatory logic of the Mesp1/Mesp2 genomic region.","evidence":"Cultured PSM induction system, chromatin conformation capture, transgenic reporters","pmids":["35025872"],"confidence":"Medium","gaps":["Whether this enhancer-sharing occurs in vivo during normal embryogenesis was not confirmed","Factors mediating the loop formation were not identified"]},{"year":2023,"claim":"Discovery that MESP2 binds TCF7L2 and inhibits the TCF4/β-catenin complex to suppress SKP2, thereby stabilizing p27 to restrain gastric cancer cell proliferation, revealed a Wnt-pathway-antagonistic function outside developmental contexts.","evidence":"Co-immunoprecipitation, ChIP, luciferase assays, in vitro and xenograft overexpression/knockdown in gastric cancer cells","pmids":["36854722"],"confidence":"Medium","gaps":["Whether this TCF7L2 interaction is relevant in normal developmental tissues was not tested","Structural basis of MESP2–TCF7L2 interaction is unknown","Independent replication in additional cancer types is lacking"]},{"year":null,"claim":"The E3 ubiquitin ligase(s) responsible for MESP2-induced Tbx6 degradation remain unidentified, the structural basis for MESP2's non-transcriptional destabilization of MAML1 is unknown, and the full spectrum of direct genomic targets of MESP2 across its developmental and non-developmental roles has not been determined by genome-wide approaches.","evidence":"","pmids":[],"confidence":"High","gaps":["E3 ligase for Tbx6 degradation not identified","No genome-wide binding profile (ChIP-seq) for MESP2","MESP2 protein structure not solved","Relative importance of transcriptional vs post-translational Notch suppression modes in vivo not quantified"]}],"mechanism_profile":{"molecular_activity":[{"term_id":"GO:0003677","term_label":"DNA binding","supporting_discovery_ids":[9,10,16]},{"term_id":"GO:0140110","term_label":"transcription regulator activity","supporting_discovery_ids":[0,6,9,10,14,16]},{"term_id":"GO:0098772","term_label":"molecular function regulator activity","supporting_discovery_ids":[14,19]}],"localization":[{"term_id":"GO:0005634","term_label":"nucleus","supporting_discovery_ids":[9,14,16]}],"pathway":[{"term_id":"R-HSA-162582","term_label":"Signal Transduction","supporting_discovery_ids":[0,3,5,6,14,19]},{"term_id":"R-HSA-1266738","term_label":"Developmental Biology","supporting_discovery_ids":[0,2,7,8,12]},{"term_id":"R-HSA-74160","term_label":"Gene expression (Transcription)","supporting_discovery_ids":[8,9,10,13]},{"term_id":"R-HSA-392499","term_label":"Metabolism of proteins","supporting_discovery_ids":[12,15]}],"complexes":[],"partners":["TBX6","MAML1","TCF7L2","RIPPLY2"],"other_free_text":[]},"mechanistic_narrative":"MESP2 is a basic helix-loop-helix (bHLH) transcription factor that serves as a master regulator of vertebrate somitogenesis, translating the temporal segmentation clock into spatial rostro-caudal somite patterning. MESP2 is transcriptionally activated by Tbx6 binding to conserved T-box sites in its presomitic mesoderm (PSM) enhancer downstream of Notch signaling, and once expressed it directly binds E-box enhancers to activate targets including Epha4, Lfng, and Ripply2, while suppressing Notch signaling both transcriptionally (via Lfng induction) and post-translationally (by destabilizing the Notch co-activator MAML1 independently of its DNA-binding activity) [PMID:15902259, PMID:21098559, PMID:16728472, PMID:17360776]. MESP2 further defines segmental borders by inducing ubiquitin-proteasome-dependent degradation of Tbx6, and its own expression is terminated by a Ripply2-mediated negative feedback loop, ensuring periodic and spatially restricted segment formation [PMID:18579680, PMID:17360776]. Beyond somitogenesis, MESP2 regulates cardiac neural crest cell proliferation through cell-cycle factors and interacts with TCF7L2/β-catenin to modulate Wnt target gene expression [PMID:32572506, PMID:36854722]."},"prefetch_data":{"uniprot":{"accession":"Q0VG99","full_name":"Mesoderm posterior protein 2","aliases":["Class C basic helix-loop-helix protein 6","bHLHc6"],"length_aa":397,"mass_kda":41.8,"function":"Transcription factor with important role in somitogenesis. Defines the rostrocaudal patterning of the somite by participating in distinct Notch pathways. Also regulates the FGF signaling pathway. Specifies the rostral half of the somites. Generates rostro-caudal polarity of somites by down-regulating in the presumptive rostral domain DLL1, a Notch ligand. Participates in the segment border formation by activating in the anterior presomitic mesoderm LFNG, a negative regulator of DLL1-Notch signaling. Acts as a strong suppressor of Notch activity. Together with MESP1 is involved in the epithelialization of somitic mesoderm and in the development of cardiac mesoderm","subcellular_location":"Nucleus","url":"https://www.uniprot.org/uniprotkb/Q0VG99/entry"},"depmap":{"release":"DepMap","has_data":true,"is_common_essential":false,"resolved_as":"","url":"https://depmap.org/portal/gene/MESP2","classification":"Not Classified","n_dependent_lines":2,"n_total_lines":1208,"dependency_fraction":0.0016556291390728477},"opencell":{"profiled":false,"resolved_as":"","ensg_id":"","cell_line_id":"","localizations":[],"interactors":[],"url":"https://opencell.sf.czbiohub.org/search/MESP2","total_profiled":1310},"omim":[{"mim_id":"610928","title":"SRY-BOX 17; SOX17","url":"https://www.omim.org/entry/610928"},{"mim_id":"609813","title":"SPONDYLOCOSTAL DYSOSTOSIS 3, AUTOSOMAL RECESSIVE; SCDO3","url":"https://www.omim.org/entry/609813"},{"mim_id":"608689","title":"MESODERM POSTERIOR BASIC HELIX-LOOP-HELIX TRANSCRIPTION FACTOR 1; MESP1","url":"https://www.omim.org/entry/608689"},{"mim_id":"608681","title":"SPONDYLOCOSTAL DYSOSTOSIS 2, AUTOSOMAL RECESSIVE; SCDO2","url":"https://www.omim.org/entry/608681"},{"mim_id":"608059","title":"HES FAMILY bHLH TRANSCRIPTION FACTOR 7; HES7","url":"https://www.omim.org/entry/608059"}],"hpa":{"profiled":true,"resolved_as":"","reliability":"","locations":[],"tissue_specificity":"Not detected","tissue_distribution":"Not detected","driving_tissues":[],"url":"https://www.proteinatlas.org/search/MESP2"},"hgnc":{"alias_symbol":["SCDO2","bHLHc6"],"prev_symbol":[]},"alphafold":{"accession":"Q0VG99","domains":[{"cath_id":"4.10.280,4.10.280","chopping":"88-154","consensus_level":"high","plddt":90.7555,"start":88,"end":154}],"viewer_url":"https://alphafold.ebi.ac.uk/entry/Q0VG99","model_url":"https://alphafold.ebi.ac.uk/files/AF-Q0VG99-F1-model_v6.cif","pae_url":"https://alphafold.ebi.ac.uk/files/AF-Q0VG99-F1-predicted_aligned_error_v6.png","plddt_mean":54.19},"mouse_models":{"mgi_url":"https://www.informatics.jax.org/marker/summary?nomen=MESP2","jax_strain_url":"https://www.jax.org/strain/search?query=MESP2"},"sequence":{"accession":"Q0VG99","fasta_url":"https://rest.uniprot.org/uniprotkb/Q0VG99.fasta","uniprot_url":"https://www.uniprot.org/uniprotkb/Q0VG99/entry","alphafold_viewer_url":"https://alphafold.ebi.ac.uk/entry/Q0VG99"}},"corpus_meta":[{"pmid":"9242490","id":"PMC_9242490","title":"Mesp2: a novel mouse gene expressed in the presegmented mesoderm and essential for segmentation initiation.","date":"1997","source":"Genes & development","url":"https://pubmed.ncbi.nlm.nih.gov/9242490","citation_count":282,"is_preprint":false},{"pmid":"15902259","id":"PMC_15902259","title":"The Mesp2 transcription factor establishes segmental borders by suppressing Notch activity.","date":"2005","source":"Nature","url":"https://pubmed.ncbi.nlm.nih.gov/15902259","citation_count":204,"is_preprint":false},{"pmid":"10887078","id":"PMC_10887078","title":"MesP1 and MesP2 are essential for the development of cardiac mesoderm.","date":"2000","source":"Development (Cambridge, England)","url":"https://pubmed.ncbi.nlm.nih.gov/10887078","citation_count":196,"is_preprint":false},{"pmid":"10932180","id":"PMC_10932180","title":"Mesp2 initiates somite segmentation through the Notch signalling pathway.","date":"2000","source":"Nature genetics","url":"https://pubmed.ncbi.nlm.nih.gov/10932180","citation_count":173,"is_preprint":false},{"pmid":"15122512","id":"PMC_15122512","title":"Mutated MESP2 causes spondylocostal dysostosis in humans.","date":"2004","source":"American journal of human genetics","url":"https://pubmed.ncbi.nlm.nih.gov/15122512","citation_count":125,"is_preprint":false},{"pmid":"16505380","id":"PMC_16505380","title":"Tbx6-mediated Notch signaling controls somite-specific Mesp2 expression.","date":"2006","source":"Proceedings of the National Academy of Sciences of the United States of America","url":"https://pubmed.ncbi.nlm.nih.gov/16505380","citation_count":116,"is_preprint":false},{"pmid":"17360776","id":"PMC_17360776","title":"The negative regulation of Mesp2 by mouse Ripply2 is required to establish the rostro-caudal patterning within a somite.","date":"2007","source":"Development (Cambridge, England)","url":"https://pubmed.ncbi.nlm.nih.gov/17360776","citation_count":86,"is_preprint":false},{"pmid":"18579680","id":"PMC_18579680","title":"Mesp2 and Tbx6 cooperatively create periodic patterns coupled with the clock machinery during mouse somitogenesis.","date":"2008","source":"Development (Cambridge, England)","url":"https://pubmed.ncbi.nlm.nih.gov/18579680","citation_count":85,"is_preprint":false},{"pmid":"12900443","id":"PMC_12900443","title":"Feedback loops comprising Dll1, Dll3 and Mesp2, and differential involvement of Psen1 are essential for rostrocaudal patterning of somites.","date":"2003","source":"Development (Cambridge, England)","url":"https://pubmed.ncbi.nlm.nih.gov/12900443","citation_count":77,"is_preprint":false},{"pmid":"18485326","id":"PMC_18485326","title":"Mutations in the MESP2 gene cause spondylothoracic dysostosis/Jarcho-Levin syndrome.","date":"2008","source":"American journal of human genetics","url":"https://pubmed.ncbi.nlm.nih.gov/18485326","citation_count":61,"is_preprint":false},{"pmid":"16728472","id":"PMC_16728472","title":"Identification of Epha4 enhancer required for segmental expression and the regulation by Mesp2.","date":"2006","source":"Development (Cambridge, England)","url":"https://pubmed.ncbi.nlm.nih.gov/16728472","citation_count":61,"is_preprint":false},{"pmid":"9739106","id":"PMC_9739106","title":"Genetic rescue of segmentation defect in MesP2-deficient mice by MesP1 gene replacement.","date":"1998","source":"Mechanisms of development","url":"https://pubmed.ncbi.nlm.nih.gov/9739106","citation_count":56,"is_preprint":false},{"pmid":"11578861","id":"PMC_11578861","title":"Transcriptional regulation of Mesp1 and Mesp2 genes: differential usage of enhancers during development.","date":"2001","source":"Mechanisms of development","url":"https://pubmed.ncbi.nlm.nih.gov/11578861","citation_count":43,"is_preprint":false},{"pmid":"15677726","id":"PMC_15677726","title":"Differential contributions of Mesp1 and Mesp2 to the epithelialization and rostro-caudal patterning of somites.","date":"2005","source":"Development (Cambridge, England)","url":"https://pubmed.ncbi.nlm.nih.gov/15677726","citation_count":38,"is_preprint":false},{"pmid":"21098559","id":"PMC_21098559","title":"The repression of Notch signaling occurs via the destabilization of mastermind-like 1 by Mesp2 and is essential for somitogenesis.","date":"2010","source":"Development (Cambridge, England)","url":"https://pubmed.ncbi.nlm.nih.gov/21098559","citation_count":36,"is_preprint":false},{"pmid":"18849530","id":"PMC_18849530","title":"Functional importance of evolutionally conserved Tbx6 binding sites in the presomitic mesoderm-specific enhancer of Mesp2.","date":"2008","source":"Development (Cambridge, England)","url":"https://pubmed.ncbi.nlm.nih.gov/18849530","citation_count":34,"is_preprint":false},{"pmid":"17394251","id":"PMC_17394251","title":"Segmental border is defined by the key transcription factor Mesp2, by means of the suppression of Notch activity.","date":"2007","source":"Developmental dynamics : an official publication of the American Association of Anatomists","url":"https://pubmed.ncbi.nlm.nih.gov/17394251","citation_count":32,"is_preprint":false},{"pmid":"25641698","id":"PMC_25641698","title":"Segmental border is defined by Ripply2-mediated Tbx6 repression independent of Mesp2.","date":"2015","source":"Developmental biology","url":"https://pubmed.ncbi.nlm.nih.gov/25641698","citation_count":23,"is_preprint":false},{"pmid":"18328678","id":"PMC_18328678","title":"Identification of presomitic mesoderm (PSM)-specific Mesp1 enhancer and generation of a PSM-specific Mesp1/Mesp2-null mouse using BAC-based rescue technology.","date":"2008","source":"Mechanisms of development","url":"https://pubmed.ncbi.nlm.nih.gov/18328678","citation_count":21,"is_preprint":false},{"pmid":"37315842","id":"PMC_37315842","title":"Retinoic acid enhances ovarian steroidogenesis by regulating granulosa cell proliferation and MESP2/STAR/CYP11A1 pathway.","date":"2023","source":"Journal of advanced research","url":"https://pubmed.ncbi.nlm.nih.gov/37315842","citation_count":20,"is_preprint":false},{"pmid":"20503311","id":"PMC_20503311","title":"Autosomal dominant spondylocostal dysostosis in three generations of a Macedonian family: Negative mutation analysis of DLL3, MESP2, HES7, and LFNG.","date":"2010","source":"American journal of medical genetics. Part A","url":"https://pubmed.ncbi.nlm.nih.gov/20503311","citation_count":19,"is_preprint":false},{"pmid":"34679163","id":"PMC_34679163","title":"Formal proof of the requirement of MESP1 and MESP2 in mesoderm specification and their transcriptional control via specific enhancers in mice.","date":"2021","source":"Development (Cambridge, England)","url":"https://pubmed.ncbi.nlm.nih.gov/34679163","citation_count":17,"is_preprint":false},{"pmid":"17477400","id":"PMC_17477400","title":"Transcription factors Mesp2 and Paraxis have critical roles in axial musculoskeletal formation.","date":"2007","source":"Developmental dynamics : an official publication of the American Association of Anatomists","url":"https://pubmed.ncbi.nlm.nih.gov/17477400","citation_count":17,"is_preprint":false},{"pmid":"23727513","id":"PMC_23727513","title":"Metameric pattern of intervertebral disc/vertebral body is generated independently of Mesp2/Ripply-mediated rostro-caudal patterning of somites in the mouse embryo.","date":"2013","source":"Developmental biology","url":"https://pubmed.ncbi.nlm.nih.gov/23727513","citation_count":17,"is_preprint":false},{"pmid":"23238123","id":"PMC_23238123","title":"Spatiotemporal disorder in the axial skeleton development of the Mesp2-null mouse: a model of spondylocostal dysostosis and spondylothoracic dysostosis.","date":"2012","source":"Bone","url":"https://pubmed.ncbi.nlm.nih.gov/23238123","citation_count":11,"is_preprint":false},{"pmid":"36854722","id":"PMC_36854722","title":"MESP2 binds competitively to TCF4 to suppress gastric cancer progression by regulating the SKP2/p27 axis.","date":"2023","source":"Cell death discovery","url":"https://pubmed.ncbi.nlm.nih.gov/36854722","citation_count":9,"is_preprint":false},{"pmid":"32572506","id":"PMC_32572506","title":"MESP2 variants contribute to conotruncal heart defects by inhibiting cardiac neural crest cell proliferation.","date":"2020","source":"Journal of molecular medicine (Berlin, Germany)","url":"https://pubmed.ncbi.nlm.nih.gov/32572506","citation_count":4,"is_preprint":false},{"pmid":"35025872","id":"PMC_35025872","title":"Repurposing of the enhancer-promoter communication underlies the compensation of Mesp2 by Mesp1.","date":"2022","source":"PLoS genetics","url":"https://pubmed.ncbi.nlm.nih.gov/35025872","citation_count":3,"is_preprint":false},{"pmid":"22744456","id":"PMC_22744456","title":"Mutation analysis of MESP2, HES7 and DUSP6 gene exons in patients with congenital scoliosis.","date":"2012","source":"Studies in health technology and informatics","url":"https://pubmed.ncbi.nlm.nih.gov/22744456","citation_count":3,"is_preprint":false}],"cost":{"stage1":{"model":"claude-sonnet-4-6","input_tokens":14729,"output_tokens":4531,"usd":0.056076},"stage2":{"model":"claude-opus-4-6","input_tokens":8032,"output_tokens":3492,"usd":0.19119},"total_usd":0.247266,"stage1_batch_id":"msgbatch_01Mgbec4vM6c9vXht7JVJzss","stage2_batch_id":"msgbatch_01JkuuH5RB2BdJNsgnhjbC6s","note":"batch pricing = 50% of standard"},"stage1_raw":"```json\n{\n  \"discoveries\": [\n    {\n      \"year\": 1997,\n      \"finding\": \"Mesp2 is a bHLH transcription factor expressed in the rostral presomitic mesoderm that is essential for segmentation initiation; Mesp2-null mice lack segmented somites and show altered expression of Mox-1, Pax-1, Dll1, Notch1, Notch2, and FGFR1, indicating Mesp2 controls sclerotomal polarity by regulating Notch-delta and FGF signaling pathways.\",\n      \"method\": \"Gene targeting (knockout mouse), in situ hybridization, immunohistochemistry\",\n      \"journal\": \"Genes & development\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 — clean KO with defined cellular phenotype, replicated in subsequent studies\",\n      \"pmids\": [\"9242490\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 1998,\n      \"finding\": \"MesP1 can functionally substitute for MesP2 in somitogenesis in a dosage-dependent manner, and both proteins act via Notch-delta and FGF signaling systems, as shown by knock-in of Mesp1 cDNA into the Mesp2 locus rescuing skeletal defects and restoring Notch1, Notch2, and FGFR-1 expression.\",\n      \"method\": \"Gene knock-in (Mesp1 cDNA into Mesp2 locus), skeletal analysis, in situ hybridization\",\n      \"journal\": \"Mechanisms of development\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 — genetic epistasis/rescue experiment with defined molecular readouts\",\n      \"pmids\": [\"9739106\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2000,\n      \"finding\": \"MesP1 and MesP2 are essential for cardiac and paraxial mesoderm formation; double-knockout embryos lack mesodermal layer due to defective migratory activity of mesodermal cells, and chimera analysis showed the cardiac mesoderm defect is cell-autonomous while the paraxial mesoderm defect is non-cell-autonomous.\",\n      \"method\": \"Double knockout mouse, chimera analysis, molecular marker analysis\",\n      \"journal\": \"Development (Cambridge, England)\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 — genetic KO with chimera analysis providing cell-autonomy distinction\",\n      \"pmids\": [\"10887078\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2000,\n      \"finding\": \"Mesp2 initiates rostro-caudal polarity by controlling two Notch signaling pathways: it activates a presenilin-1 (Ps1)-independent Notch cascade to suppress Dll1 expression and specify the rostral somite half, while Ps1-mediated Notch signaling induces Dll1 in the caudal half.\",\n      \"method\": \"Genetic epistasis analysis (Mesp2, Ps1, Dll1 mutant combinations), in situ hybridization\",\n      \"journal\": \"Nature genetics\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 — genetic epistasis with multiple mutant combinations, replicated in subsequent studies\",\n      \"pmids\": [\"10932180\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2001,\n      \"finding\": \"Mesp2 expression is controlled by at least two distinct enhancers: an early mesodermal enhancer (EME) and a presomitic mesoderm enhancer (PSME), with a separate suppressor element restricting expression to the rostral PSM.\",\n      \"method\": \"Transient transgenic analysis, enhancer deletion studies\",\n      \"journal\": \"Mechanisms of development\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 — in vivo transgenic enhancer mapping, single lab\",\n      \"pmids\": [\"11578861\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2003,\n      \"finding\": \"Positive and negative feedback loops comprising Dll1 and Mesp2 are crucial for rostrocaudal patterning; Mesp2 affects rostrocaudal properties more directly than Dll1 or Dll3, and Psen1 is differentially required for Dll1-Notch signaling activation of Dll1 but not for the Dll3-Notch pathway that counteracts it.\",\n      \"method\": \"Genetic epistasis analysis using Dll1, Dll3, Mesp2, and Psen1 mutant combinations\",\n      \"journal\": \"Development (Cambridge, England)\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 — multiple genetic epistasis combinations, replicated finding\",\n      \"pmids\": [\"12900443\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2005,\n      \"finding\": \"Mesp2 suppresses Notch activity in the anterior PSM through induction of the lunatic fringe gene (Lfng), thereby establishing segmental borders at the interface between Notch1-activated and Notch1-repressed domains; this was demonstrated by genetic and biochemical studies including visualization of endogenous Notch1 activity oscillation.\",\n      \"method\": \"Knock-in reporter mice for Notch1 activity visualization, genetic epistasis, biochemical assays\",\n      \"journal\": \"Nature\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1–2 — multiple orthogonal methods (in vivo reporter, genetics, biochemistry) in a high-impact study\",\n      \"pmids\": [\"15902259\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2005,\n      \"finding\": \"Mesp2 and Mesp1 have distinct roles in somitogenesis: Mesp2 is essential for segment border formation and rostral identity (cell-autonomously), while Mesp1 plays a greater role in epithelialization of somitic mesoderm; chimera analyses showed Mesp mutant cells exert non-cell-autonomous effects on normal cell somite formation.\",\n      \"method\": \"Chimera analysis with Mesp2-null and Mesp1/Mesp2 double-null cells\",\n      \"journal\": \"Development (Cambridge, England)\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 — chimera analysis providing cell-autonomy dissection with multiple genotypes\",\n      \"pmids\": [\"15677726\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2006,\n      \"finding\": \"Tbx6 directly binds to the Mesp2 upstream enhancer region and mediates Notch signaling to activate Mesp2 transcription in the anterior presomitic mesoderm.\",\n      \"method\": \"ChIP, reporter assays in cultured cells, Tbx6-null mouse analysis, in situ hybridization\",\n      \"journal\": \"Proceedings of the National Academy of Sciences of the United States of America\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 — ChIP confirming direct binding, supported by genetic evidence in Tbx6-null mice\",\n      \"pmids\": [\"16505380\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2006,\n      \"finding\": \"Mesp2 directly binds to an E-box-containing enhancer of Epha4 and activates its expression in the anterior PSM; forced expression of Mesp2 in somitic cells activates Epha4 and represses the caudal gene Uncx4.1, and induces abnormal epithelialized structures consistent with Mesp2 driving segmental border formation via cellular epithelialization genes.\",\n      \"method\": \"Transgenic reporter analysis, transient luciferase assay, ChIP/direct binding, gain-of-function Mesp2 misexpression\",\n      \"journal\": \"Development (Cambridge, England)\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1–2 — direct binding to enhancer confirmed plus functional gain-of-function phenotype\",\n      \"pmids\": [\"16728472\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2007,\n      \"finding\": \"Mesp2 directly binds the Ripply2 gene enhancer and activates its transcription; Ripply2 (a WRPW-motif co-repressor) in turn negatively regulates Mesp2 in a feedback loop, so that loss of Ripply2 causes prolonged Mesp2 expression leading to rostralized somites via suppression of Notch signaling.\",\n      \"method\": \"Microarray, enhancer binding assay (ChIP/gel shift), Ripply2 knockout mouse, genetic epistasis\",\n      \"journal\": \"Development (Cambridge, England)\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 — direct binding confirmed, KO phenotype analyzed, feedback loop genetically validated\",\n      \"pmids\": [\"17360776\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2007,\n      \"finding\": \"Mesp2 and Paraxis genetically interact in sclerotomal development; Mesp2/Paraxis double-null mice show severe reduction of vertebral body and neural arch components. Pax3 expression in the anteriormost PSM is regulated by both Mesp2 and Paraxis. Yeast two-hybrid analyses showed no direct protein-protein interaction between Mesp2 and Paraxis, indicating the interaction is indirect.\",\n      \"method\": \"Double knockout mouse, yeast two-hybrid, in situ hybridization\",\n      \"journal\": \"Developmental dynamics\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 — genetic double KO with defined phenotype and negative protein interaction test, single lab\",\n      \"pmids\": [\"17477400\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2008,\n      \"finding\": \"Mesp2 transcription is periodically activated by waves of Notch activity and spatially defined by Tbx6 protein. Once translated, Mesp2 protein induces rapid post-translational degradation of Tbx6 protein via the ubiquitin-proteasome pathway, thereby defining the anterior border of Mesp2 expression and translating clock periodicity into spatial segmental patterning.\",\n      \"method\": \"High-resolution fluorescent in situ hybridization, immunohistochemistry, proteasome inhibitor treatment\",\n      \"journal\": \"Development (Cambridge, England)\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 — multiple orthogonal methods demonstrating post-translational mechanism with pharmacological validation\",\n      \"pmids\": [\"18579680\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2008,\n      \"finding\": \"Two evolutionarily conserved Tbx6 binding sites in the Mesp2 PSM-specific enhancer are indispensable in vivo for Mesp2 expression; enhancer knockout mice bearing mutations in these sites show absent Mesp2 PSM expression and skeletal segmentation defects identical to Mesp2-null mice.\",\n      \"method\": \"Enhancer knockout mouse, ChIP, transgenic reporter analysis\",\n      \"journal\": \"Development (Cambridge, England)\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 — in vivo enhancer mutagenesis confirmed by ChIP and phenocopy of null mouse\",\n      \"pmids\": [\"18849530\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2010,\n      \"finding\": \"Mesp2 suppresses Notch signaling by inducing destabilization of mastermind-like 1 (MAML1), a core Notch transcriptional co-activator; this function is independent of Mesp2's role as a transcription factor, as shown by a dominant-negative Rbpj knock-in into the Mesp2 locus almost completely rescuing Mesp2-null segmental defects.\",\n      \"method\": \"Knock-in mouse (dominant-negative Rbpj into Mesp2 locus), biochemical co-immunoprecipitation and protein stability assays, genetic rescue\",\n      \"journal\": \"Development (Cambridge, England)\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1–2 — genetic rescue combined with biochemical evidence of MAML1 destabilization, multiple orthogonal approaches\",\n      \"pmids\": [\"21098559\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2015,\n      \"finding\": \"Ripply2 represses Tbx6 protein post-translationally in a Mesp2-independent manner to establish the segmental border; Ripply2 knock-in into the Mesp2 locus can generate the anterior Tbx6 domain limit even without Mesp2, and ectopic Ripply2 suppresses Tbx6 protein (not mRNA), demonstrating post-translational Tbx6 regulation.\",\n      \"method\": \"Transgenic overexpression, Ripply2 knock-in into Mesp2 locus, ectopic expression in PSM, protein/mRNA analysis\",\n      \"journal\": \"Developmental biology\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 — multiple transgenic approaches distinguishing protein vs. mRNA level regulation\",\n      \"pmids\": [\"25641698\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2020,\n      \"finding\": \"MESP2 directly regulates transcriptional activities of downstream genes MYOCD, GATA4, NKX2.5, and CFC1, and promotes cardiac neural crest cell (CNCC) proliferation by regulating cell cycle factors p21cip1 and Cdk4; MESP2 variants found in conotruncal heart defect patients inhibit CNCC proliferation.\",\n      \"method\": \"Luciferase reporter assays, primary mouse CNCC cultures, cell cycle analysis, variant functional analysis in HEK293T and JoMa1 cells\",\n      \"journal\": \"Journal of molecular medicine\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2–3 — functional assays in cultured cells with patient variants, single lab\",\n      \"pmids\": [\"32572506\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2021,\n      \"finding\": \"MESP1 and MESP2 expression in the early mesoderm is regulated by the cooperation of two independent enhancers containing T-box- and TCF/Lef-binding sites; deletion of both enhancers causes downregulation of both genes and heart formation defects, and upregulation of Mesp2 in Mesp1 KO embryos compensates for Mesp1 loss in mesoderm specification.\",\n      \"method\": \"Genome-editing KO without selection markers, enhancer deletion analysis, RT-PCR\",\n      \"journal\": \"Development (Cambridge, England)\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 — clean CRISPR KO and enhancer deletion with phenotypic readout, single lab\",\n      \"pmids\": [\"34679163\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2022,\n      \"finding\": \"Upon loss of Mesp2, the Mesp2 enhancer directly interacts with the Mesp1 promoter via genomic looping established during PSM development, thereby upregulating Mesp1 as a compensatory mechanism; this enhancer-promoter communication is established by genomic arrangement independently of Mesp2 disruption.\",\n      \"method\": \"Cultured PSM induction system, chromatin conformation assays, transgenic reporter analysis\",\n      \"journal\": \"PLoS genetics\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 — in vitro PSM system combined with chromatin conformation data, single lab\",\n      \"pmids\": [\"35025872\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2023,\n      \"finding\": \"MESP2 binds to TCF7L2/TCF4 and inhibits activation of the TCF4/β-catenin transcriptional complex, reducing its occupancy on the SKP2 promoter and thereby promoting p27 accumulation to suppress gastric cancer cell growth and invasion.\",\n      \"method\": \"Co-immunoprecipitation, ChIP, luciferase reporter assays, in vitro and in vivo overexpression/knockdown\",\n      \"journal\": \"Cell death discovery\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2–3 — Co-IP and ChIP supporting direct interaction, functional rescue by SKP2 KD, single lab\",\n      \"pmids\": [\"36854722\"],\n      \"is_preprint\": false\n    }\n  ],\n  \"current_model\": \"MESP2 is a bHLH transcription factor expressed in the anterior presomitic mesoderm that acts as a central regulator of vertebrate somitogenesis by: (1) directly binding E-box enhancers to activate target genes (Epha4, Lfng, Ripply2) and suppress Notch signaling both transcriptionally (via Lfng induction) and post-translationally (by inducing MAML1 destabilization independently of its transcription factor function); (2) inducing post-translational degradation of Tbx6 via the ubiquitin-proteasome pathway to spatially define the segmental border; (3) being transcriptionally activated itself by Tbx6 binding to conserved T-box sites in its PSM-specific enhancer downstream of Notch signaling; and (4) participating in a negative feedback loop with Ripply2 to ensure periodically restricted Mesp2 expression, thereby translating the temporal segmentation clock signal into spatial rostro-caudal somite patterning.\"\n}\n```","stage2_raw":"```json\n{\n  \"mechanistic_narrative\": \"MESP2 is a basic helix-loop-helix (bHLH) transcription factor that serves as a master regulator of vertebrate somitogenesis, translating the temporal segmentation clock into spatial rostro-caudal somite patterning. MESP2 is transcriptionally activated by Tbx6 binding to conserved T-box sites in its presomitic mesoderm (PSM) enhancer downstream of Notch signaling, and once expressed it directly binds E-box enhancers to activate targets including Epha4, Lfng, and Ripply2, while suppressing Notch signaling both transcriptionally (via Lfng induction) and post-translationally (by destabilizing the Notch co-activator MAML1 independently of its DNA-binding activity) [PMID:15902259, PMID:21098559, PMID:16728472, PMID:17360776]. MESP2 further defines segmental borders by inducing ubiquitin-proteasome-dependent degradation of Tbx6, and its own expression is terminated by a Ripply2-mediated negative feedback loop, ensuring periodic and spatially restricted segment formation [PMID:18579680, PMID:17360776]. Beyond somitogenesis, MESP2 regulates cardiac neural crest cell proliferation through cell-cycle factors and interacts with TCF7L2/β-catenin to modulate Wnt target gene expression [PMID:32572506, PMID:36854722].\",\n  \"teleology\": [\n    {\n      \"year\": 1997,\n      \"claim\": \"Establishing that MESP2 is essential for somite segmentation resolved the question of which transcription factor initiates rostro-caudal patterning in the presomitic mesoderm.\",\n      \"evidence\": \"Mesp2-null mice lack segmented somites and show disrupted Notch, Dll1, and FGF pathway gene expression\",\n      \"pmids\": [\"9242490\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Mechanism by which MESP2 controls Notch/Dll1 expression was unknown\", \"Direct transcriptional targets not identified\", \"Whether MESP2 acts cell-autonomously was untested\"]\n    },\n    {\n      \"year\": 1998,\n      \"claim\": \"Demonstrating that MESP1 knock-in into the Mesp2 locus rescues segmentation established functional redundancy between the two paralogs and confirmed that MESP2's role in somitogenesis operates through shared downstream pathways.\",\n      \"evidence\": \"Mesp1 cDNA knock-in into Mesp2 locus restores Notch1/2 and FGFR1 expression and rescues skeletal defects dose-dependently\",\n      \"pmids\": [\"9739106\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"The basis for unique versus shared MESP1/MESP2 functions was unresolved\", \"Direct DNA targets of either factor not yet identified\"]\n    },\n    {\n      \"year\": 2000,\n      \"claim\": \"Genetic epistasis with Presenilin-1 and Dll1 mutants revealed that MESP2 establishes rostral somite identity by activating a Presenilin-independent Notch pathway that suppresses Dll1, while Presenilin-mediated Notch signaling drives caudal identity — resolving how one transcription factor generates opposing compartment fates.\",\n      \"evidence\": \"Compound mutant analysis of Mesp2, Ps1, and Dll1; in situ hybridization for compartment markers\",\n      \"pmids\": [\"10932180\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Identity of the Presenilin-independent Notch pathway component was unknown\", \"Whether MESP2 directly acts on Dll1 enhancer or acts indirectly was unresolved\"]\n    },\n    {\n      \"year\": 2005,\n      \"claim\": \"Identification of Lunatic fringe (Lfng) as the Mesp2-induced suppressor of Notch activity provided the molecular mechanism by which MESP2 creates the segmental border at the interface of Notch-active and Notch-repressed domains.\",\n      \"evidence\": \"Knock-in Notch1 activity reporters, genetic epistasis, and biochemical assays in mouse embryos\",\n      \"pmids\": [\"15902259\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Whether MESP2 directly binds the Lfng enhancer was not shown\", \"Non-transcriptional mechanisms of Notch suppression by MESP2 were not yet discovered\"]\n    },\n    {\n      \"year\": 2006,\n      \"claim\": \"ChIP-based demonstration that Tbx6 directly binds the Mesp2 upstream enhancer, and that this binding mediates Notch-dependent Mesp2 activation, established the input logic gating MESP2 transcription in the anterior PSM.\",\n      \"evidence\": \"ChIP in cultured cells, reporter assays, analysis in Tbx6-null mice\",\n      \"pmids\": [\"16505380\", \"18849530\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"How Notch signaling cooperates with Tbx6 at the enhancer at the chromatin level was unresolved\", \"Periodicity mechanism linking the clock to Tbx6/Mesp2 activation was not fully explained\"]\n    },\n    {\n      \"year\": 2006,\n      \"claim\": \"Direct binding of MESP2 to the Epha4 E-box enhancer and gain-of-function induction of epithelialization genes identified the first confirmed direct transcriptional target and linked MESP2 to the cellular mechanics of border formation.\",\n      \"evidence\": \"ChIP/direct binding assay, transgenic reporter, luciferase assay, Mesp2 misexpression in somitic cells\",\n      \"pmids\": [\"16728472\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Full repertoire of direct MESP2 transcriptional targets remained incomplete\", \"How Epha4 activation translates to epithelialization was unexplored\"]\n    },\n    {\n      \"year\": 2007,\n      \"claim\": \"Discovery that MESP2 directly activates Ripply2, which then feeds back to terminate MESP2 expression, explained how MESP2 expression is temporally restricted to a single somite-forming unit.\",\n      \"evidence\": \"Microarray, ChIP/gel shift for direct Ripply2 enhancer binding, Ripply2 KO mouse with rostralized somite phenotype\",\n      \"pmids\": [\"17360776\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Mechanism by which Ripply2 represses Mesp2 (direct or indirect, transcriptional or post-translational) was unclear\", \"Whether Ripply2 feeds back on Tbx6 independently of MESP2 was unknown\"]\n    },\n    {\n      \"year\": 2008,\n      \"claim\": \"Demonstrating that MESP2 induces ubiquitin-proteasome-mediated degradation of Tbx6 protein provided the key mechanism by which MESP2 sharpens its own expression boundary and converts temporal clock periodicity into a spatial segment.\",\n      \"evidence\": \"High-resolution FISH, immunohistochemistry, proteasome inhibitor treatment in mouse embryos\",\n      \"pmids\": [\"18579680\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"The E3 ubiquitin ligase responsible for Tbx6 degradation was not identified\", \"Whether MESP2 directly participates in the Tbx6 degradation complex or acts indirectly was unresolved\"]\n    },\n    {\n      \"year\": 2010,\n      \"claim\": \"Revealing that MESP2 destabilizes MAML1 to suppress Notch signaling independently of its DNA-binding/transcription factor function uncovered a dual-mode mechanism — transcriptional (via Lfng) and post-translational (via MAML1) — for Notch suppression by a single bHLH factor.\",\n      \"evidence\": \"Dominant-negative Rbpj knock-in into Mesp2 locus rescuing segmental defects; Co-IP and protein stability assays for MAML1\",\n      \"pmids\": [\"21098559\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"The domain of MESP2 responsible for MAML1 destabilization was not mapped\", \"Whether MESP2 directly binds MAML1 or requires an adaptor was not resolved\"]\n    },\n    {\n      \"year\": 2015,\n      \"claim\": \"Ripply2 knock-in into the Mesp2 locus demonstrated that Ripply2 can independently suppress Tbx6 protein post-translationally, refining the segmental border model by showing that MESP2 is not the sole regulator of Tbx6 degradation.\",\n      \"evidence\": \"Ripply2 knock-in into Mesp2 locus, ectopic Ripply2 expression in PSM, protein versus mRNA analysis\",\n      \"pmids\": [\"25641698\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"The relative contributions of MESP2 versus Ripply2 to Tbx6 degradation in normal development were not quantified\"]\n    },\n    {\n      \"year\": 2020,\n      \"claim\": \"Functional analysis of MESP2 in cardiac neural crest cells expanded its known roles beyond somitogenesis, showing it regulates proliferation via p21/Cdk4 and activates cardiac transcription factors, with patient variants linked to conotruncal heart defects.\",\n      \"evidence\": \"Luciferase reporter assays, primary mouse CNCC cultures, cell cycle analysis, patient variant functional tests in HEK293T/JoMa1 cells\",\n      \"pmids\": [\"32572506\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"In vivo cardiac phenotype of MESP2 loss-of-function specifically in neural crest was not demonstrated\", \"Whether these cardiac functions are bHLH DNA-binding dependent or involve the MAML1 destabilization mode was untested\"]\n    },\n    {\n      \"year\": 2022,\n      \"claim\": \"Chromatin conformation studies revealed that the Mesp2 enhancer can loop to activate the Mesp1 promoter upon Mesp2 loss, explaining the compensatory upregulation of Mesp1 and the locus-level regulatory logic of the Mesp1/Mesp2 genomic region.\",\n      \"evidence\": \"Cultured PSM induction system, chromatin conformation capture, transgenic reporters\",\n      \"pmids\": [\"35025872\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Whether this enhancer-sharing occurs in vivo during normal embryogenesis was not confirmed\", \"Factors mediating the loop formation were not identified\"]\n    },\n    {\n      \"year\": 2023,\n      \"claim\": \"Discovery that MESP2 binds TCF7L2 and inhibits the TCF4/β-catenin complex to suppress SKP2, thereby stabilizing p27 to restrain gastric cancer cell proliferation, revealed a Wnt-pathway-antagonistic function outside developmental contexts.\",\n      \"evidence\": \"Co-immunoprecipitation, ChIP, luciferase assays, in vitro and xenograft overexpression/knockdown in gastric cancer cells\",\n      \"pmids\": [\"36854722\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Whether this TCF7L2 interaction is relevant in normal developmental tissues was not tested\", \"Structural basis of MESP2–TCF7L2 interaction is unknown\", \"Independent replication in additional cancer types is lacking\"]\n    },\n    {\n      \"year\": null,\n      \"claim\": \"The E3 ubiquitin ligase(s) responsible for MESP2-induced Tbx6 degradation remain unidentified, the structural basis for MESP2's non-transcriptional destabilization of MAML1 is unknown, and the full spectrum of direct genomic targets of MESP2 across its developmental and non-developmental roles has not been determined by genome-wide approaches.\",\n      \"evidence\": \"\",\n      \"pmids\": [],\n      \"confidence\": \"High\",\n      \"gaps\": [\"E3 ligase for Tbx6 degradation not identified\", \"No genome-wide binding profile (ChIP-seq) for MESP2\", \"MESP2 protein structure not solved\", \"Relative importance of transcriptional vs post-translational Notch suppression modes in vivo not quantified\"]\n    }\n  ],\n  \"mechanism_profile\": {\n    \"molecular_activity\": [\n      {\"term_id\": \"GO:0003677\", \"supporting_discovery_ids\": [9, 10, 16]},\n      {\"term_id\": \"GO:0140110\", \"supporting_discovery_ids\": [0, 6, 9, 10, 14, 16]},\n      {\"term_id\": \"GO:0098772\", \"supporting_discovery_ids\": [14, 19]}\n    ],\n    \"localization\": [\n      {\"term_id\": \"GO:0005634\", \"supporting_discovery_ids\": [9, 14, 16]}\n    ],\n    \"pathway\": [\n      {\"term_id\": \"R-HSA-162582\", \"supporting_discovery_ids\": [0, 3, 5, 6, 14, 19]},\n      {\"term_id\": \"R-HSA-1266738\", \"supporting_discovery_ids\": [0, 2, 7, 8, 12]},\n      {\"term_id\": \"R-HSA-74160\", \"supporting_discovery_ids\": [8, 9, 10, 13]},\n      {\"term_id\": \"R-HSA-392499\", \"supporting_discovery_ids\": [12, 15]}\n    ],\n    \"complexes\": [],\n    \"partners\": [\n      \"TBX6\",\n      \"MAML1\",\n      \"TCF7L2\",\n      \"RIPPLY2\"\n    ],\n    \"other_free_text\": []\n  }\n}\n```"}