Affinage

MED12

Mediator of RNA polymerase II transcription subunit 12 · UniProt Q93074

Length
2177 aa
Mass
243.1 kDa
Annotated
2026-06-10
100 papers in source corpus 34 papers cited in narrative 34 extracted findings
Cross-family judge vs UniProt: Affinage preferred faithfulness: 7/7 claims corpus-supported (100%)

Mechanistic narrative

Synthesis pass · prose summary of the discoveries below

MED12 is a subunit of the Mediator CDK8 kinase module that couples gene-specific transcriptional control to the activation of the Mediator-associated kinases CDK8 and its paralog CDK19, and it functions across embryonic development, stem cell homeostasis, and multiple human disease states (PMID:19047373, PMID:29440396, PMID:31988137). Within the module, MED12—but not MED13—is required to activate CDK8 kinase activity on substrates including histone H3, the Pol II CTD, and TFIIH (PMID:19047373); mechanistically, the N-terminal segment of MED12 wraps around CDK8, positioning a defined 'activation helix' adjacent to the CDK8 T-loop to stimulate it and remodel its active site (PMID:31988137), while MED13 binds the MED12 C-terminus and gates a mutation-sensitive conformational switch governing Cyclin C-CDK8/19 association and activation (PMID:29440396). A coherent set of disease mutations partition along this architecture: uterine leiomyoma exon 1/exon 2 mutations map to a minimal Cyclin C-CDK8 activation domain (aa 15–80) and abolish Mediator-associated kinase activity without abolishing CDK8 binding, producing a stereotyped expression signature (PMID:24746821, PMID:24980722, PMID:30099503), whereas prostate cancer L1224F instead disrupts MED12 contacts with core Mediator subunits rather than the kinase module (PMID:26383637). Loss of this kinase activity in fibroid cells drives R-loop accumulation and ATR-dependent replication stress and large-scale 3D genome compartmentalization changes, and is sufficient to deregulate developmental signaling outputs including Wnt/β-catenin, SHH/GLI3, and NOTCH1 (PMID:35418189, PMID:37429859, PMID:28771672). Beyond the module, MED12 acts as a transcriptional coactivator and partner for sequence-specific regulators including Nanog, MEF2, Sox9, Pygopus, and the progesterone receptor to drive cell-type-specific gene programs (PMID:18451032, PMID:28724790, PMID:19036726, PMID:16712834, PMID:30538295), and it carries a kinase-independent cytoplasmic role suppressing TGF-β signaling through direct interaction with TGF-βR2, a function that modulates drug resistance and DNA-repair/fork-protection phenotypes (PMID:23178117, PMID:34871431). MED12 chromatin function at enhancers is further tuned by CARM1-mediated arginine methylation (R1899/R1862/R1912), which recruits the Tudor-domain effector TDRD3 and licenses noncoding-RNA interactions at ERα enhancers (PMID:26601288, PMID:30456381, PMID:29628309). Germline missense mutations in MED12 cause the X-linked intellectual disability disorders Opitz-Kaveggia (FG) syndrome and Lujan syndrome (PMID:17334363, PMID:17369503).

Mechanistic history

Synthesis pass · year-by-year structured walk · 19 steps
  1. 2003 Medium

    Established the ancestral, conserved role of the MED12-containing submodule as a negative regulator that controls whether Mediator engages RNA Pol II.

    Evidence Biochemical purification of Mediator from S. pombe with co-fractionation and genetic epistasis

    PMID:12738880

    Open questions at the time
    • Yeast ortholog data; human MED12 contribution not directly assayed
    • Does not define the molecular basis of Pol II exclusion
  2. 2006 Medium

    Placed MED12 as a developmental coactivator by tying its loss-of-function phenotype to a specific transcription factor pathway.

    Evidence Zebrafish forward genetic screen and epistasis with Sox9 mutants

    PMID:16712834

    Open questions at the time
    • No direct MED12-Sox9 binding shown
    • Mechanism of coactivation undefined
  3. 2007 Medium

    Linked MED12 to human Mendelian disease, showing recurrent germline missense mutations cause two allelic X-linked intellectual disability syndromes.

    Evidence Gene sequencing and linkage in FG and Lujan syndrome families

    PMID:17334363 PMID:17369503

    Open questions at the time
    • No in vitro mechanistic assay connecting mutations to Mediator dysfunction in these reports
    • Causal molecular pathway to neurodevelopmental phenotype not established
  4. 2008 High

    Defined MED12 as the essential activator of CDK8 kinase activity within the module and identified module substrates, establishing the core biochemical function.

    Evidence Purification and insect-cell reconstitution of the CDK8 subcomplex with kinase assays, subunit removal, MS, and EM

    PMID:19047373

    Open questions at the time
    • Structural basis of activation not resolved at this stage
    • In vivo substrate relevance on chromatin only partially addressed
  5. 2008 High

    Connected MED12 to specific transcription-factor programs by showing physical and functional partnership with Pygopus (Wnt) and Nanog (pluripotency).

    Evidence Drosophila epistasis and reciprocal Co-IP; Co-IP, ChIP, and knockdown concordance in ES cells

    PMID:18451032 PMID:19036726

    Open questions at the time
    • Whether these interactions require kinase activity not resolved
    • Direct vs. bridged interactions not fully distinguished
  6. 2010 High

    Demonstrated MED12 is essential in vivo for canonical Wnt and Wnt/PCP signaling during mammalian embryogenesis.

    Evidence Conditional/hypomorphic mouse models with developmental phenotyping

    PMID:20630950

    Open questions at the time
    • Does not separate kinase-dependent from kinase-independent contributions
    • Direct transcriptional targets in vivo not enumerated
  7. 2012 High

    Revealed a kinase-independent cytoplasmic function: MED12 directly binds TGF-βR2 to suppress TGF-β signaling, controlling targeted-therapy resistance.

    Evidence Genome-scale RNAi screen, reciprocal Co-IP, fractionation, and TGF-βR inhibitor rescue across cancer lines

    PMID:23178117

    Open questions at the time
    • Structural basis of MED12-TGF-βR2 interaction undefined
    • How nuclear and cytoplasmic pools are partitioned not established
  8. 2012 High

    Mechanistically linked the FG/Lujan disease mutations to derepression of SHH signaling via impaired CDK8-mediated suppression of GLI3.

    Evidence ChIP, Co-IP, reporter assays, and expression analysis in patient-derived cells

    PMID:23091001

    Open questions at the time
    • Quantitative link between kinase-activity loss and GLI3 output not fully resolved
    • Neurodevelopmental consequence of SHH derepression not directly tested
  9. 2014 High

    Pinpointed the biochemical defect of uterine leiomyoma mutations: exon 1/2 mutations disrupt the MED12–Cyclin C interface, abolishing Mediator kinase activity and producing a stereotyped expression signature.

    Evidence AP-MS of WT vs. mutant MED12, Co-IP, kinase assays, and transcriptome profiling

    PMID:24746821 PMID:24980722

    Open questions at the time
    • Did not yet localize a discrete activation domain
    • Downstream oncogenic mechanism from kinase loss not yet defined
  10. 2015 High

    Established that the leiomyoma mutation is a gain-of-function driver in vivo causing genomic instability, and identified CARM1 arginine methylation as a chromatin-tuning modification.

    Evidence Conditional knock-in mouse with cytogenetics; in vitro methylation, site mutagenesis, and chemosensitivity assays

    PMID:26193636 PMID:26601288

    Open questions at the time
    • Mechanism linking mutation to chromosomal rearrangement not fully defined
    • Full set of CARM1-methylation-dependent functions incomplete
  11. 2016 High

    Defined a kinase-independent, essential role at enhancers: MED12 stabilizes P300/H3K27Ac to maintain HSC identity, and partners with PRC1/ncRNA for Polycomb gene control.

    Evidence Conditional in vivo deletion, ChIP-seq, and epistasis with other module subunits; Co-IP/ChIP in mESCs

    PMID:27096886 PMID:27570068

    Open questions at the time
    • How MED12 stabilizes P300 mechanistically not resolved
    • ncRNA identities incompletely defined
  12. 2017 High

    Extended MED12's coactivator partnerships to MEF2-driven cardiac calcium-handling genes and showed mutation-specific, cell-type-specific control of immediate-early genes.

    Evidence Cardiac-specific KO with Co-IP, ChIP, calcium imaging; ChIP and expression in patient-derived cells

    PMID:28369444 PMID:28724790

    Open questions at the time
    • Whether MEF2 coactivation depends on kinase activity unresolved
    • Mechanism determining mutation-specific IEG patterns unknown
  13. 2018 High

    Resolved the conformational logic of activation (MED13 gating, CDK19 stimulation) and showed cancer mutations partition by interface: leiomyoma mutations hit the kinase module while prostate L1224F hits core-Mediator contacts.

    Evidence In vitro kinase reconstitution with domain mapping; quantitative AP-MS and kinase assays

    PMID:26383637 PMID:29440396

    Open questions at the time
    • Atomic structure of the MED13-gated state not solved
    • Functional consequence of disrupted core-Mediator contacts on transcription not mapped
  14. 2018 High

    Connected MED12 arginine methylation to enhancer function, showing methyl-R1899 recruits TDRD3 and JMJD6 enables CARM1 access to license ncRNA binding and Pol II pause release at ERα enhancers.

    Evidence MS substrate mapping, site-specific methylation validation, ChIP-seq, RNA-binding assays, and reciprocal Co-IP

    PMID:29628309 PMID:30456381

    Open questions at the time
    • Identity and function of the activating ncRNAs incompletely defined
    • Generality beyond ERα enhancers not established
  15. 2018 High

    Localized the minimal Cyclin C-CDK8 activation domain (aa 15–80) encompassing all recorded fibroid mutations, and tied MED12 loss to NOTCH1 activation in CLL.

    Evidence Kinase assays on patient-derived Mediator with mutation mapping; CDK8-inhibitor assay, NICD analysis, and mutual exclusivity in CLL

    PMID:28771672 PMID:30099503

    Open questions at the time
    • NOTCH evidence is convergent/indirect for the mechanism
    • Whether all listed pathways are direct CDK8 substrates not uniformly shown
  16. 2019 High

    Revealed an additional cytoplasmic/cytoskeletal function: MED12 loss activates LIMK2, disrupting actin dynamics and cytokinesis, causing multinucleation and senescence.

    Evidence CRISPR KO, live imaging, RNA-seq, reconstitution, and xenografts in NSCLC

    PMID:31072327

    Open questions at the time
    • Direct vs. transcriptional control of LIMK2 not fully distinguished
    • Relationship to Mediator function unclear
  17. 2020 High

    Provided the structural mechanism of CDK8 activation—the MED12 activation helix positioned at the T-loop—and showed cancer mutations alter helix positioning without reducing CDK8 affinity, also explaining altered inhibitor sensitivity.

    Evidence In vitro biochemistry, XL-MS, kinase inhibitor assays, and transcriptome analysis; AP-1 enhancer architecture by ChIP-seq/Hi-C/RNA-seq

    PMID:31988137 PMID:32094355

    Open questions at the time
    • High-resolution structure of the activated complex still lacking
    • How helix mispositioning maps to enhancer/AP-1 changes not mechanistically linked
  18. 2022 High

    Linked Mediator-kinase loss to genome stability, showing MED12 mutation/CDK8 inhibition triggers R-loop accumulation and ATR-dependent replication stress rescuable by RNaseH.

    Evidence Patient-tissue IHC, single-molecule DNA fiber analysis, CDK8/19 inhibition, and RNaseH rescue

    PMID:35418189

    Open questions at the time
    • Mechanism connecting kinase loss to R-loop formation not defined
    • Whether replication stress drives tumorigenesis vs. is a byproduct unresolved
  19. 2023 High

    Showed that engineered fibroid mutations reprogram transcription, metabolism, and 3D genome compartmentalization, integrating prior signaling and chromatin observations into a higher-order genome-architecture phenotype.

    Evidence CRISPR knock-in with RNA-seq, Hi-C, metabolomics, and in vivo xenografts

    PMID:37429859

    Open questions at the time
    • Causal chain from kinase loss to compartment switching not delineated
    • Whether compartment changes are cause or consequence of transcriptional change unresolved

Open questions

Synthesis pass · forward-looking unresolved questions
  • How MED12's many context-specific functions—kinase activation, kinase-independent enhancer maintenance, cytoplasmic TGF-β/LIMK2 control, and genome architecture—are coordinately partitioned within a single protein remains unresolved.
  • No unified model distinguishing nuclear module-bound vs. cytoplasmic pools
  • No high-resolution structure of the full activated CDK8 module with MED12
  • Direct CDK8 substrate set responsible for each oncogenic pathway not fully enumerated

Mechanism profile

Synthesis pass · controlled-vocabulary classification · explore literature graph →
Molecular activity
GO:0140110 transcription regulator activity 5 GO:0098772 molecular function regulator activity 3 GO:0003723 RNA binding 2 GO:0060089 molecular transducer activity 1
Localization
GO:0005634 nucleus 3 GO:0005654 nucleoplasm 2 GO:0005829 cytosol 1
Pathway
R-HSA-162582 Signal Transduction 4 R-HSA-1643685 Disease 4 R-HSA-1266738 Developmental Biology 3 R-HSA-4839726 Chromatin organization 3 R-HSA-74160 Gene expression (Transcription) 3 R-HSA-73894 DNA Repair 2
Partners
CARM1CDK19CDK8CYCLIN CMED13MEF2PGRTGFBR2
Complex memberships
Mediator CDK8 kinase moduleMediator complex

Evidence

Reading pass · 34 per-paper findings extracted from the source corpus
Year Finding Method Journal Conf PMIDs
2008 MED12 (Med12) is essential for activating CDK8 kinase activity within the CDK8 subcomplex; Med12—but not Med13—is required for CDK8 kinase activity. The 600-kDa CDK8 subcomplex (CDK8, Cyclin C, Med12, Med13) was purified from human cells and reconstituted in insect cells, revealing novel substrates including histone H3, Med13, and CDK8 itself in addition to TFIIH and Pol II CTD. Mediator itself enables CDK8 kinase activity on chromatin. Biochemical purification of endogenous and recombinant CDK8 subcomplex; kinase assays with recombinant components; mass spectrometry; electron microscopy Molecular and cellular biology High 19047373
2008 Drosophila Med12 (Kohtalo/Kto) physically interacts with Pygopus and is required for transcription of Wingless (Wnt) target genes. Med12 and Med13 (skuld) act downstream of β-catenin stabilization both in vivo and in cell culture, and their physical interaction with Pygopus depends on the Pygopus N-terminal domain. Genetic epistasis in Drosophila; co-immunoprecipitation; cell culture transcription assays Proceedings of the National Academy of Sciences of the United States of America High 18451032
2012 MED12 is partially cytoplasmic and negatively regulates TGF-βR2 through direct physical interaction. MED12 suppression activates TGF-β signaling, which causes MEK/ERK activation and drives resistance to ALK, EGFR, MEK, and BRAF inhibitors. Inhibition of TGF-βR signaling restores drug sensitivity in MED12-knockdown cells. Large-scale RNAi screen; co-immunoprecipitation; subcellular fractionation; rescue experiments with TGF-βR inhibitors; epistasis in multiple cancer cell lines Cell High 23178117
2014 Uterine leiomyoma-linked mutations in MED12 exon 2 cause a highly specific decrease in MED12 association with Cyclin C-CDK8/CDK19 and loss of Mediator-associated CDK kinase activity. Mechanistically, these mutations disrupt the MED12–Cyclin C binding interface that is required for MED12-mediated stimulation of CDK8 kinase activity. Established by affinity-purification mass spectrometry of wild-type vs. mutant MED12 interaction profiles. Affinity-purification mass spectrometry (AP-MS); co-immunoprecipitation; CDK kinase activity assays Cell reports High 24746821
2014 MED12 exon 1 mutations (in-frame insertion/deletions) in uterine leiomyomas disrupt the interaction between MED12 and Cyclin C and CDK8/19 and abolish Mediator-associated CDK kinase activity, producing the same unique global gene expression pattern as exon 2 mutations (with RAD51B as the most upregulated gene). Immunoprecipitation; kinase activity assays; transcriptome-wide expression profiling; mutation screening by sequencing Human mutation High 24980722
2007 A recurrent missense mutation in MED12 (c.2881C>T, R961W) causes Opitz-Kaveggia (FG) syndrome, demonstrating that MED12 functions as a thyroid receptor-associated protein in the Mediator complex and that its mutation leads to X-linked intellectual disability with craniofacial and behavioral anomalies. Exome/gene sequencing in affected families; genetic linkage Nature genetics Medium 17334363
2007 A different missense mutation in MED12 (p.N1007S) causes Lujan syndrome, allelic to Opitz-Kaveggia syndrome, establishing MED12 as the causative gene for both X-linked intellectual disability syndromes. Gene sequencing in original Lujan syndrome family and second family Journal of medical genetics Medium 17369503
2012 FG/R961W and Lujan/N1007S mutations in MED12 disrupt a Mediator-imposed constraint on GLI3-dependent Sonic Hedgehog (SHH) signaling. These mutations disrupt the gene-specific association of MED12 with CDK8, a suppressor of GLI3 transactivation activity. In patient-derived cells, enhanced SHH pathway activation and GLI3-target gene induction coincide with impaired CDK8 recruitment to GLI3-target gene promoters. Chromatin immunoprecipitation (ChIP); gene expression analysis in patient-derived cells; co-immunoprecipitation; reporter assays Proceedings of the National Academy of Sciences of the United States of America High 23091001
2010 Med12 is required for canonical Wnt/β-catenin signaling and Wnt/planar cell polarity (PCP) pathway in mouse embryos. Med12 hypomorphic mutant mice fail to develop beyond embryonic day 10, with severe defects in neural tube closure, axis elongation, somitogenesis, and heart formation. Med12-null embryos fail to establish anterior visceral endoderm or activate brachyury expression. Conditional gene targeting in mouse embryonic stem cells; hypomorphic mouse model; in vivo developmental analysis Development (Cambridge, England) High 20630950
2015 A Med12 missense variant (c.131G>A) expressed conditionally in mouse uterus causes leiomyoma formation via gain-of-function and drives genomic instability (chromosomal rearrangements). This variant acts epistatically to promote tumor formation even in the absence of endogenous Med12, demonstrating a gain-of-function mechanism. Conditional mouse model (CRISPR/targeted knock-in); histological analysis; cytogenetic analysis The Journal of clinical investigation High 26193636
2015 CARM1 methylates MED12 at arginine residues R1862 and R1912 (and major site R1899 in a separate study). Methylation of MED12 by CARM1 sensitizes breast cancer cells to chemotherapy drugs through suppression of p21/WAF1 transcription, a mechanism distinct from TGF-βR signaling. Mutation of these methylation sites confers chemotherapy resistance. In vitro methylation assay; site-directed mutagenesis; cell viability assays; chromatin immunoprecipitation Science advances High 26601288
2018 CARM1 methylates MED12 primarily at R1899, and the methyl-R1899 mark recruits the Tudor-domain effector TDRD3. This methylation is required for MED12 to interact with activating noncoding RNAs. CARM1 and the methyl mark it deposits are tightly associated with ERα-specific enhancers and modulate transcription of estrogen-regulated genes. CARM1-substrate motif antibody immunoprecipitation coupled with mass spectrometry; ChIP-seq; RNA-binding assays; Co-IP Life science alliance High 30456381
2018 JMJD6 interacts with MED12 in the Mediator complex and is required for MED12 to interact with CARM1. CARM1-mediated methylation of MED12 at multiple arginine sites then regulates MED12 chromatin binding at ERα-bound active enhancers, enabling RNA Pol II recruitment and transcriptional pause release of estrogen target genes. Co-immunoprecipitation; ChIP-seq; reporter assays; loss-of-function knockdown Molecular cell High 29628309
2016 MED12 is an essential regulator of hematopoietic stem cell (HSC) homeostasis in a kinase-independent manner. In vivo deletion of Med12 causes rapid bone marrow aplasia and lethality. MED12 deletion destabilizes P300 binding at lineage-specific enhancers, depleting H3K27Ac and de-activating enhancers, resulting in loss of HSC stemness signatures. Deletion of other Mediator kinase module subunits does not recapitulate this phenotype. Conditional in vivo deletion (mouse model); ChIP-seq; genetic epistasis (comparison with other kinase module subunit knockouts); bone marrow transplantation Cell stem cell High 27570068
2018 Prostate cancer-associated MED12 L1224F mutation (exon 26) promotes tumorigenesis through a mechanism distinct from leiomyoma exon 2 mutations: L1224F does not compromise MED12 interaction with Cyclin C or CDK8/19 nor Mediator-associated CDK activity, but instead disrupts interactions between MED12 and other core Mediator subunits (MED1, MED13, MED13L, MED14, MED15, MED17, MED24). Quantitative affinity-purification mass spectrometry (AP-MS); co-immunoprecipitation; kinase activity assays The Prostate High 26383637
2018 MED12 allosterically activates CDK19 (the CDK8 paralog), and uterine fibroid-linked exon 2 mutations in MED12 disrupt this CDK19 stimulatory activity. MED13 directly binds to the MED12 C-terminus, suppressing an apparent UF mutation-induced conformational change in MED12 that otherwise disrupts MED12 association with Cyclin C-CDK8/19. In the presence of MED13, mutant MED12 can bind but cannot activate Cyclin C-CDK8/19. In vitro kinase assays; co-immunoprecipitation; domain-mapping experiments The Journal of biological chemistry High 29440396
2020 The N-terminal segment of MED12 wraps around CDK8, positioning a defined 'activation helix' close to the T-loop of CDK8 to activate it. Cancer-associated mutations in this activation helix do not diminish MED12 affinity for CDK8 but likely alter the exact positioning of the helix. MED12 binding to CDK8 also remodels the CDK8 active site, precluding inhibition by type II kinase inhibitors. In vitro biochemistry; cross-linking coupled to mass spectrometry (XL-MS); kinase inhibitor assays; in vivo transcriptome analysis Proceedings of the National Academy of Sciences of the United States of America High 31988137
2017 MED12 is required for normal cardiac function; cardiac-specific deletion of Med12 in mice causes progressive dilated cardiomyopathy. Loss of MED12 disrupts expression of calcium-handling genes, alters calcium cycling and cardiac electrical activity. MED12 physically interacts with MEF2 transcription factor in cardiomyocytes and co-occupies promoters of calcium-handling genes with MEF2, enhancing MEF2 transcriptional activity. Conditional cardiac-specific mouse knockout; co-immunoprecipitation (MED12–MEF2); ChIP; calcium imaging; echocardiography JCI insight High 28724790
2008 Med12 physically interacts with Nanog in embryonic stem cells and co-occupies Nanog target promoters. Med12 knockdown in ES cells phenocopies Nanog knockdown (increased expression of Nanog-repressed targets, decreased Nanog-activated targets), establishing a functional interaction in regulating pluripotency. Co-immunoprecipitation; chromatin immunoprecipitation (ChIP); gene expression profiling after shRNA knockdown The Journal of biological chemistry High 19036726
2006 Zebrafish Trap230/Med12 functions as a coactivator for Sox9 in neural crest, otic placode, cartilage, and bone development. Loss-of-function mutation in zebrafish Med12 strongly resembles the Sox9a/Sox9b double mutant phenotype, establishing Med12 as a critical Sox9 coactivator in vertebrate development. Forward genetic screen; phenotypic analysis; genetic epistasis with Sox9 mutants Developmental biology Medium 16712834
2003 TRAP230/ARC240 (MED12) and TRAP240/ARC250 homologues form a conserved Mediator submodule with Srb10 and Srb11 that is involved in negative regulation of transcription. In S. pombe, Mediator containing this submodule is isolated only in free form devoid of RNA Pol II, whereas Mediator lacking this module associates with the polymerase—demonstrating a role in preventing Mediator–Pol II association. Biochemical purification of Mediator from S. pombe; co-fractionation with RNA Pol II; genetic epistasis (overlapping deletion phenotypes) Proceedings of the National Academy of Sciences of the United States of America Medium 12738880
2016 Med12 operates with PRC1 to silence key developmental genes in pluripotent mouse ES cells. PRC1 is required to assemble ncRNA-containing Med12–Mediator complexes. During differentiation, the H2A ubiquitin-binding protein Zrf1 abrogates PRC1–Med12 binding and facilitates Cdk8 association with Mediator, converting Mediator from a transcriptional repressor to activator for ncRNA-dependent activation of Polycomb target genes. Co-immunoprecipitation; ChIP; gene expression analysis; loss-of-function in mESCs Cell cycle (Georgetown, Tex.) Medium 27096886
2017 MED12 mutations (R206Q, N898D, R961W, N1007S, R1148H, S1165P, R1295H) each cause specific, mutation-distinct expression patterns of immediate early genes (IEGs: JUN, FOS, EGR1) in a cell-type-specific manner, reflecting the presence or absence of MED12-containing complexes at IEG promoters. Consequent expression of late-response genes (MMP-3, REST) is also disturbed, and JUN/FOS fail to be recruited to their AP1 binding sites in the MED12/p.R1295H context. Gene expression analysis in patient-derived cells; chromatin immunoprecipitation (ChIP) at IEG promoters; AP1 binding site ChIP Human molecular genetics Medium 28369444
2019 MED12 knockout in NSCLC cells causes cytokinesis failure with multinuclear phenotype and cellular senescence. Mechanistically, MED12 loss activates LIMK2, causing aberrant actin cytoskeleton remodeling and disruption of intercellular bridge abscission. Exogenous MED12 reconstitution restores actin dynamics and normal cytokinesis. CRISPR-Cas9 knockout; live cell imaging of cell division; RNA-seq; lentiviral reconstitution; LIMK2 pathway analysis; xenograft tumor model Molecular cancer High 31072327
2018 MED12 physically interacts with progesterone receptor (PR) in uterine leiomyoma tissue. The interaction between MED12 and PR, and binding of both to PR-binding sites (PRBS), and RANKL gene expression are significantly higher in leiomyomas containing the MED12 G44D mutation than in those with wild-type MED12, indicating that mutant MED12 enhances PR-driven transcription of RANKL to promote stem cell proliferation. Co-immunoprecipitation (MED12–PR); ChIP (MED12 and PR at PRBS); luciferase reporter assays; MethylCap-Seq Oncogene Medium 30538295
2021 Loss of MED12 in BRCA-deficient cells confers resistance to cisplatin and PARP inhibitors through restoration of homologous recombination and replication fork stability. This effect is mediated by MED12-dependent suppression of the TGF-β pathway, acting independently of its Mediator complex function. Ectopic TGF-β pathway activation is sufficient to overcome fork protection and DNA repair defects in BRCA-mutant cells. siRNA knockdown of MED12 in BRCA1/2-deficient cells; PARP inhibitor and cisplatin sensitivity assays; replication fork protection assay; epistasis with TGF-β pathway activation Nucleic acids research High 34871431
2021 Loss of CDK8/19 (Mediator kinase) in colorectal cancer cells leads to increased MED12 and BRD4 co-occupancy at enhancer elements, increased dependence on BET proteins for transcription of cell-essential genes, and global repression of RNA Pol II promoter occupancy. Combined CDK8/19 and BET inhibition shows synergistic growth retardation, revealing a synthetic lethal interaction. Functional genomic screens; ChIP-seq; pharmacological inhibition; genetic depletion (CDK8/19); human and mouse CRC models Molecular cell High 34910943
2022 MED12 mutations trigger aberrant R-loop formation and ATR kinase-dependent replication stress in uterine fibroids. Primary cells from MED12-mutation-positive UFs exhibit reduced replication fork speeds, increased stalled forks, and asymmetric bidirectional forks. Pharmacological inhibition of CDK8/19 kinase activity recapitulates these phenotypes, and overexpression of RNaseH (R-loop resolving enzyme) rescues them, functionally linking Mediator kinase inhibition to R-loop-induced replication stress. Immunohistochemistry (R-loop markers, ATR activation markers) on patient tissue; single-molecule DNA fiber analysis; CDK8/19 inhibitor treatment; RNaseH overexpression rescue; cell cycle analysis Scientific reports High 35418189
2017 Med12 knockdown in human uterine fibroid cells (HuLM) reduces Wnt4 and β-catenin protein levels, decreases cell proliferation, and reduces levels of cyclin D1, CDK1, CDK2, p-ERK, p-AKT, TGF-β signaling, and fibrosis-associated proteins (fibronectin, collagen type 1, PAI-1). Lentiviral shRNA stable knockdown; Western blot; cell proliferation assay Endocrinology Medium 27967206
2018 Introduction of the most common MED12 somatic mutation (c.131G>A) in human uterine myometrial cells increases Wnt4, β-catenin, mTOR, and oncogenic cyclin D1 expression, induces S-phase cell cycle entry, and inhibits autophagy, compared to cells overexpressing wild-type MED12. Stable overexpression of WT vs. mutant MED12 in immortalized UtSM cells; Western blot; cell cycle analysis Reproductive sciences (Thousand Oaks, Calif.) Medium 32046450
2023 CRISPR-engineered MED12 Gly44 mutations in uterine myometrial smooth muscle cells recapitulate UF-like transcriptional and metabolic programs (including altered tryptophan/kynurenine metabolism) and are associated with a substantial 3D genome compartmentalization switch. Mutant cells show enhanced proliferation in 3D spheres and form larger lesions in vivo with elevated collagen and ECM production. CRISPR knock-in of MED12 Gly44 mutation; RNA-seq; Hi-C (3D genome); metabolomics; in vivo xenograft model Nature communications High 37429859
2020 Modified enhancer architecture (driven by depletion of AP-1 occupancy on chromatin) is a major driver of transcriptional dysregulation in MED12-mutant uterine leiomyomas. Silencing AP-1 subunits in primary myometrium cells recapitulates transcriptional and epigenetic changes observed in leiomyomas. ChIP-seq; promoter capture Hi-C; RNA-seq of matched normal and leiomyoma tissue; AP-1 subunit siRNA knockdown Nature communications High 32094355
2018 CDK8 inhibition in MED12 mutation-positive uterine fibroids confirmed loss of Mediator-associated CDK8/19 kinase activity. A minimal Cyclin C-CDK8 activation domain on MED12 spanning amino acids 15–80 encompasses all recorded UF-linked mutations, establishing that disruption of Mediator kinase activity is the principal biochemical defect. Immunoprecipitation of Mediator from patient-derived UF tissue; CDK kinase activity assay; mutation frequency screening by sequencing The Journal of clinical endocrinology and metabolism High 30099503
2018 MED12 mutations in chronic lymphocytic leukemia (CLL) are associated with increased NOTCH1 intracellular domain (NICD) levels. NICD is identified as a target of Cyclin C-CDK8 kinase using a specific CDK8 inhibitor, and MED12 mutations are mutually exclusive with NOTCH1 mutations in CLL, suggesting MED12 mutations contribute to CLL pathogenesis by activating NOTCH signaling through loss of CDK8-mediated NOTCH1 suppression. CDK8 inhibitor assay; Western blot for NICD levels in primary CLL samples; mutual exclusivity analysis in 1429 CLL patients British journal of haematology Medium 28771672

Source papers

Stage 0 corpus · 100 papers · ranked by NIH iCite citations
Year Title Journal Citations PMID
2011 MED12, the mediator complex subunit 12 gene, is mutated at high frequency in uterine leiomyomas. Science (New York, N.Y.) 513 21868628
2012 MED12 controls the response to multiple cancer drugs through regulation of TGF-β receptor signaling. Cell 375 23178117
2008 The human CDK8 subcomplex is a histone kinase that requires Med12 for activity and can function independently of mediator. Molecular and cellular biology 191 19047373
2012 MED12 mutations in uterine fibroids--their relationship to cytogenetic subgroups. International journal of cancer 176 22223266
2007 A recurrent mutation in MED12 leading to R961W causes Opitz-Kaveggia syndrome. Nature genetics 172 17334363
2014 Exome sequencing identifies highly recurrent MED12 somatic mutations in breast fibroadenoma. Nature genetics 159 25038752
2007 The original Lujan syndrome family has a novel missense mutation (p.N1007S) in the MED12 gene. Journal of medical genetics 141 17369503
2014 Uterine leiomyoma-linked MED12 mutations disrupt mediator-associated CDK activity. Cell reports 135 24746821
2010 Med12 is essential for early mouse development and for canonical Wnt and Wnt/PCP signaling. Development (Cambridge, England) 135 20630950
2014 MED12 and HMGA2 mutations: two independent genetic events in uterine leiomyoma and leiomyosarcoma. Modern pathology : an official journal of the United States and Canadian Academy of Pathology, Inc 131 24390224
2015 Next-Gen Sequencing Exposes Frequent MED12 Mutations and Actionable Therapeutic Targets in Phyllodes Tumors. Molecular cancer research : MCR 119 25593300
2012 MED12 alterations in both human benign and malignant uterine soft tissue tumors. PloS one 109 22768200
2015 Med12 gain-of-function mutation causes leiomyomas and genomic instability. The Journal of clinical investigation 107 26193636
2008 Pygopus activates Wingless target gene transcription through the mediator complex subunits Med12 and Med13. Proceedings of the National Academy of Sciences of the United States of America 107 18451032
2003 TRAP230/ARC240 and TRAP240/ARC250 Mediator subunits are functionally conserved through evolution. Proceedings of the National Academy of Sciences of the United States of America 98 12738880
2001 Drosophila homologues of the transcriptional coactivation complex subunits TRAP240 and TRAP230 are required for identical processes in eye-antennal disc development. Development (Cambridge, England) 96 11171343
2016 Exome Sequencing of Uterine Leiomyosarcomas Identifies Frequent Mutations in TP53, ATRX, and MED12. PLoS genetics 95 26891131
2012 Somatic MED12 mutations in uterine leiomyosarcoma and colorectal cancer. British journal of cancer 94 23132392
2016 MED12 Regulates HSC-Specific Enhancers Independently of Mediator Kinase Activity to Control Hematopoiesis. Cell stem cell 93 27570068
2012 MED12 mutations in leiomyosarcoma and extrauterine leiomyoma. Modern pathology : an official journal of the United States and Canadian Academy of Pathology, Inc 83 23222489
2017 Characterization of MED12, HMGA2, and FH alterations reveals molecular variability in uterine smooth muscle tumors. Molecular cancer 78 28592321
2015 MED12 somatic mutations in fibroadenomas and phyllodes tumours of the breast. Histopathology 78 25855048
2018 JMJD6 Licenses ERα-Dependent Enhancer and Coding Gene Activation by Modulating the Recruitment of the CARM1/MED12 Co-activator Complex. Molecular cell 75 29628309
2015 MED12 methylation by CARM1 sensitizes human breast cancer cells to chemotherapy drugs. Science advances 74 26601288
2006 Zebrafish Trap230/Med12 is required as a coactivator for Sox9-dependent neural crest, cartilage and ear development. Developmental biology 74 16712834
2017 Silencing Med12 Gene Reduces Proliferation of Human Leiomyoma Cells Mediated via Wnt/β-Catenin Signaling Pathway. Endocrinology 71 27967206
2005 The zebrafish kohtalo/trap230 gene is required for the development of the brain, neural crest, and pronephric kidney. Proceedings of the National Academy of Sciences of the United States of America 70 16344459
2014 Mutations in Exon 1 highlight the role of MED12 in uterine leiomyomas. Human mutation 69 24980722
2014 MED12 mutation frequency in unselected sporadic uterine leiomyomas. Fertility and sterility 65 25108465
2013 MED12 related disorders. American journal of medical genetics. Part A 65 24123922
2015 MED12 is frequently mutated in breast phyllodes tumours: a study of 112 cases. Journal of clinical pathology 63 26018969
2013 MED12 exon 2 mutations in uterine and extrauterine smooth muscle tumors. Human pathology 62 24196187
2014 Novel MED12 gene somatic mutations in women from the Southern United States with symptomatic uterine fibroids. Molecular genetics and genomics : MGG 61 25325994
2012 MED12 mutations link intellectual disability syndromes with dysregulated GLI3-dependent Sonic Hedgehog signaling. Proceedings of the National Academy of Sciences of the United States of America 60 23091001
2018 Oncogenic exon 2 mutations in Mediator subunit MED12 disrupt allosteric activation of cyclin C-CDK8/19. The Journal of biological chemistry 58 29440396
2013 MED12 exon 2 mutations in histopathological uterine leiomyoma variants. European journal of human genetics : EJHG 58 23443020
2020 A precisely positioned MED12 activation helix stimulates CDK8 kinase activity. Proceedings of the National Academy of Sciences of the United States of America 57 31988137
2008 Role for Med12 in regulation of Nanog and Nanog target genes. The Journal of biological chemistry 54 19036726
2017 Multiple clinical characteristics separate MED12-mutation-positive and -negative uterine leiomyomas. Scientific reports 53 28432313
2015 Distribution of MED12 mutations in fibroadenomas and phyllodes tumors of the breast--implications for tumor biology and pathological diagnosis. Genes, chromosomes & cancer 49 25931199
2015 MED12 and uterine smooth muscle oncogenesis: State of the art and perspectives. European journal of cancer (Oxford, England : 1990) 48 26037152
2020 Altered chromatin landscape and enhancer engagement underlie transcriptional dysregulation in MED12 mutant uterine leiomyomas. Nature communications 47 32094355
2008 Multiple roles for Med12 in vertebrate endoderm development. Developmental biology 47 18394596
2018 CARM1 methylates MED12 to regulate its RNA-binding ability. Life science alliance 43 30456381
2015 MED12 exon 2 mutations in phyllodes tumors of the breast. Cancer medicine 43 25865354
2018 Progesterone receptor integrates the effects of mutated MED12 and altered DNA methylation to stimulate RANKL expression and stem cell proliferation in uterine leiomyoma. Oncogene 40 30538295
2016 MED12 mutations and FH inactivation are mutually exclusive in uterine leiomyomas. British journal of cancer 40 27187686
2013 Clinical and neurocognitive characterization of a family with a novel MED12 gene frameshift mutation. American journal of medical genetics. Part A 40 24039113
2020 Introduction of Somatic Mutation in MED12 Induces Wnt4/β-Catenin and Disrupts Autophagy in Human Uterine Myometrial Cell. Reproductive sciences (Thousand Oaks, Calif.) 39 32046450
2015 Somatic MED12 mutations in prostate cancer and uterine leiomyomas promote tumorigenesis through distinct mechanisms. The Prostate 38 26383637
2015 Mutational analysis of MED12 in fibroadenomas and phyllodes tumors of the breast by means of targeted next-generation sequencing. Breast cancer research and treatment 36 26093648
2018 HMGA2 and MED12 alterations frequently co-occur in uterine leiomyomas. Gynecologic oncology 35 30017537
2017 MED12 mutations and NOTCH signalling in chronic lymphocytic leukaemia. British journal of haematology 35 28771672
2014 MED12 overexpression is a frequent event in castration-resistant prostate cancer. Endocrine-related cancer 34 24938407
2012 MED12 mutations occurring in benign and malignant mammalian smooth muscle tumors. Genes, chromosomes & cancer 34 23225304
2018 MED12, TERT promoter and RBM15 mutations in primary and recurrent phyllodes tumours. British journal of cancer 33 29315289
2021 MED12 and BRD4 cooperate to sustain cancer growth upon loss of mediator kinase. Molecular cell 31 34910943
2019 MED12, TERT and RARA in fibroepithelial tumours of the breast. Journal of clinical pathology 30 31662438
2018 Mediator Kinase Disruption in MED12-Mutant Uterine Fibroids From Hispanic Women of South Texas. The Journal of clinical endocrinology and metabolism 30 30099503
2016 A novel MED12 mutation: Evidence for a fourth phenotype. American journal of medical genetics. Part A 30 27312080
2016 MED12 mutations in breast phyllodes tumors: evidence of temporal tumoral heterogeneity and identification of associated critical signaling pathways. Oncotarget 30 27806318
2014 Cell cultures in uterine leiomyomas: rapid disappearance of cells carrying MED12 mutations. Genes, chromosomes & cancer 30 24446130
2013 Exomic landscape of MED12 mutation-negative and -positive uterine leiomyomas. International journal of cancer 30 23913526
2020 De novo variants in MED12 cause X-linked syndromic neurodevelopmental disorders in 18 females. Genetics in medicine : official journal of the American College of Medical Genetics 29 33244165
2020 De novo loss-of-function variants in X-linked MED12 are associated with Hardikar syndrome in females. Genetics in medicine : official journal of the American College of Medical Genetics 28 33244166
2017 MED12 regulates a transcriptional network of calcium-handling genes in the heart. JCI insight 28 28724790
2017 Factors affecting the loss of MED12-mutated leiomyoma cells during in vitro growth. Oncotarget 27 28410233
2016 Frequency of MED12 mutations in phyllodes tumors: Inverse correlation with histologic grade. Genes, chromosomes & cancer 27 26856273
2016 Dual role of Med12 in PRC1-dependent gene repression and ncRNA-mediated transcriptional activation. Cell cycle (Georgetown, Tex.) 27 27096886
2007 Role of MED12 in transcription and human behavior. Pharmacogenomics 27 17716226
2022 Aberrant R-loop-induced replication stress in MED12-mutant uterine fibroids. Scientific reports 25 35418189
2019 MED12 exerts an emerging role in actin-mediated cytokinesis via LIMK2/cofilin pathway in NSCLC. Molecular cancer 25 31072327
1999 The genomic structure and developmental expression patterns of the human OPA-containing gene (HOPA). Human genetics 25 10480376
2021 Loss of MED12 activates the TGFβ pathway to promote chemoresistance and replication fork stability in BRCA-deficient cells. Nucleic acids research 24 34871431
2016 Frequency and Spectrum of MED12 Exon 2 Mutations in Multiple Versus Solitary Uterine Leiomyomas From Russian Patients. International journal of gynecological pathology : official journal of the International Society of Gynecological Pathologists 24 26630226
2021 Frequency of MED12 Mutation in Relation to Tumor and Patient's Clinical Characteristics: a Meta-analysis. Reproductive sciences (Thousand Oaks, Calif.) 23 33569750
2018 Analysis of MED12 Mutation in Multiple Uterine Leiomyomas in South Korean patients. International journal of medical sciences 23 29333096
2018 Loss of MED12 Induces Tumor Dormancy in Human Epithelial Ovarian Cancer via Downregulation of EGFR. Cancer research 23 29735544
2018 The power of the Mediator complex-Expanding the genetic architecture and phenotypic spectrum of MED12-related disorders. Clinical genetics 23 30006928
2017 MED12-related XLID disorders are dose-dependent of immediate early genes (IEGs) expression. Human molecular genetics 23 28369444
2018 Recurrent MED12 exon 2 mutations in benign breast fibroepithelial lesions in adolescents and young adults. Journal of clinical pathology 22 30467240
2013 MED12 mutations in human diseases. Protein & cell 22 23836153
2023 Engineered MED12 mutations drive leiomyoma-like transcriptional and metabolic programs by altering the 3D genome compartmentalization. Nature communications 21 37429859
2015 The study of MED12 gene mutations in uterine leiomyomas from Iranian patients. Tumour biology : the journal of the International Society for Oncodevelopmental Biology and Medicine 21 26298726
2020 Insights into the regulatory role and clinical relevance of mediator subunit, MED12, in human diseases. Journal of cellular physiology 20 33174211
2016 A Computational Protein Phenotype Prediction Approach to Analyze the Deleterious Mutations of Human MED12 Gene. Journal of cellular biochemistry 20 26813965
2016 Tubular, lactating, and ductal adenomas are devoid of MED12 Exon2 mutations, and ductal adenomas show recurrent mutations in GNAS and the PI3K-AKT pathway. Genes, chromosomes & cancer 20 27438523
2021 MED12-Related (Neuro)Developmental Disorders: A Question of Causality. Genes 19 33925166
2021 Uterine cellular leiomyomas are characterized by common HMGA2 aberrations, followed by chromosome 1p deletion and MED12 mutation: morphological, molecular, and immunohistochemical study of 52 cases. Virchows Archiv : an international journal of pathology 19 34626221
2018 Expanded Somatic Mutation Spectrum of MED12 Gene in Uterine Leiomyomas of Saudi Arabian Women. Frontiers in genetics 19 30619444
2007 Drosophila TRAP230/240 are essential coactivators for Atonal in retinal neurogenesis. Developmental biology 19 17585897
2022 Different DNA methylome, transcriptome and histological features in uterine fibroids with and without MED12 mutations. Scientific reports 18 35618793
2022 Myometrial oxidative stress drives MED12 mutations in leiomyoma. Cell & bioscience 18 35869560
2018 Comparative analysis of AKT and the related biomarkers in uterine leiomyomas with MED12, HMGA2, and FH mutations. Genes, chromosomes & cancer 18 29790226
2008 Behavior of 10 patients with FG syndrome (Opitz-Kaveggia syndrome) and the p.R961W mutation in the MED12 gene. American journal of medical genetics. Part A 18 18973276
2003 Polymorphism analysis of HOPA: a candidate gene for schizophrenia. American journal of medical genetics. Part B, Neuropsychiatric genetics : the official publication of the International Society of Psychiatric Genetics 18 14582143
2022 Tryptophan 2,3-Dioxygenase-2 in Uterine Leiomyoma: Dysregulation by MED12 Mutation Status. Reproductive sciences (Thousand Oaks, Calif.) 17 35064560
2022 MED12 mutations in uterine leiomyomas: prediction of volume reduction by gonadotropin-releasing hormone agonists. American journal of obstetrics and gynecology 17 36150519
2019 MED12 missense mutation in a three-generation family. Clinical characterization of MED12-related disorders and literature review. European journal of medical genetics 17 31536828
2017 MED12 is recurrently mutated in Middle Eastern colorectal cancer. Gut 17 28183795

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