Affinage

TLL1

Tolloid-like protein 1 · UniProt O43897

Length
1013 aa
Mass
114.7 kDa
Annotated
2026-04-28
21 papers in source corpus 10 papers cited in narrative 10 extracted findings

Mechanistic narrative

Synthesis pass · prose summary of the discoveries below

TLL1 is an extracellular astacin-family metalloprotease that processes diverse substrates to regulate extracellular matrix assembly, BMP/TGF-β signaling, and axon guidance. It cleaves procollagens (procollagen C-proteinase activity), Chordin (releasing BMPs from inhibition), DMP1, latent TGF-β1 (activating TGF-β signaling), and SLIT2 (generating fragments required for axon fasciculation), with its activity requiring furin/prohormone convertase-mediated activation and being negatively regulated by calcium-dependent dimerization through non-catalytic domains that restrict substrate access (PMID:12808086, PMID:20043912, PMID:40760092, PMID:41626796). TLL1 shares substantial functional redundancy with BMP1 in procollagen and DMP1 processing in bone and dental tissues, and combined loss of both proteases causes osteogenesis imperfecta, periodontal ligament disorganization, and dentin defects (PMID:24419319, PMID:28000152). Loss of TLL1 in mice causes embryonic lethality with cardiac septal defects, while a gain-of-function catalytic domain mutation (p.T253A) with prolonged enzymatic activity causes autosomal dominant mitral valve prolapse in humans (PMID:10331975, PMID:39880331).

Mechanistic history

Synthesis pass · year-by-year structured walk · 8 steps
  1. 1999 High

    The first demonstration that TLL1 has a non-redundant developmental role established it as essential for cardiac septation, resolving its function beyond that of a BMP1 paralog.

    Evidence Tll1 knockout mice showed mid-gestational lethality with incomplete interventricular septum and abnormal heart positioning; expression was specific to precardiac tissue and endocardium.

    PMID:10331975

    Open questions at the time
    • Molecular substrate(s) mediating the cardiac phenotype not identified
    • Whether TLL1 acts through ECM processing or BMP signaling in heart development was unresolved
  2. 2003 High

    Establishing that TLL1 cleaves Chordin in vivo and contributes residual procollagen C-proteinase activity in the absence of BMP1 resolved the question of functional overlap between BMP1-family members for both ECM assembly and BMP signaling.

    Evidence Bmp1/Tll1 double-null mouse embryos combined with biochemical substrate cleavage assays showed both Chordin and procollagen as direct TLL1 substrates.

    PMID:12808086

    Open questions at the time
    • Relative contributions of TLL1 vs. BMP1 to each substrate in specific tissues remained unclear
    • Additional non-procollagen substrates not yet surveyed
  3. 2009 High

    Demonstrating that TLL1 forms a calcium-dependent dimer whose non-catalytic domains restrict substrate access provided the first autoregulatory mechanism for this protease, explaining why truncated forms matching BMP1's domain structure show higher activity toward Chordin.

    Evidence Biophysical characterization and truncation/activity assays showed dimerization reduces catalytic activity toward Chordin.

    PMID:20043912

    Open questions at the time
    • Structural basis of the dimer interface at atomic resolution not determined
    • Whether dimerization is regulated in vivo or is constitutive was unknown
    • Relevance of dimerization to substrates other than Chordin not tested
  4. 2014 High

    Postnatal conditional ablation of both BMP1 and TLL1 revealed their overlapping roles in bone homeostasis and identified DMP1 as an additional shared substrate, establishing that TLL1 functions beyond embryonic development in skeletal maintenance.

    Evidence Conditional double-knockout mice developed osteogenesis imperfecta with spontaneous fractures, reduced procollagen and DMP1 processing, and activated Wnt signaling.

    PMID:24419319

    Open questions at the time
    • Individual contribution of TLL1 vs. BMP1 in bone not genetically separated
    • Mechanism linking reduced DMP1 processing to Wnt activation not elucidated
  5. 2017 Medium

    Extension of the double-knockout approach to dental and periodontal tissues showed that TLL1/BMP1 are required for dentin formation and periodontal ligament integrity, with secondary inflammatory contributions.

    Evidence Conditional double knockouts in Col1a1-expressing cells showed dental and periodontal defects; systemic antibiotics partially rescued the phenotype.

    PMID:28000152 PMID:28068493

    Open questions at the time
    • TLL1-specific contribution versus BMP1 not separable in these studies
    • Direct substrates mediating periodontal phenotype beyond procollagen and DMP1 not identified
  6. 2022 Medium

    Identification of TLL1 as a promoter of bacterial invasion through TGF-β pathway activation broadened its functional scope to innate immune modulation at epithelial barriers.

    Evidence shRNA knockdown and TGF-β inhibitor treatment in Caco-2 cells showed TLL1-dependent Klebsiella pneumoniae adhesion/invasion.

    PMID:36087399

    Open questions at the time
    • Direct TLL1 substrate in the TGF-β activation step not biochemically identified
    • In vivo relevance in intestinal infection not confirmed
    • Single cell line and single lab
  7. 2025 Medium

    Direct biochemical demonstration that TLL1 cleaves latent TGF-β1 and consequent upregulation of PD-L1 linked TLL1 to tumor immune evasion, while a gain-of-function TLL1 mutation causing mitral valve prolapse connected its proteolytic activity to human valve disease.

    Evidence TGF-β1 cleavage assays, tumor models with TLL1 depletion/overexpression, T cell-specific TLL1 transgenic mice, and WES/enzymatic assays on the p.T253A variant in a mitral valve prolapse family.

    PMID:39880331 PMID:40760092

    Open questions at the time
    • Mechanism by which excess TLL1 activity causes valve prolapse (substrate identity in valve ECM) not determined
    • Whether TLL1-mediated TGF-β1 activation is relevant outside tumor/infection contexts is unknown
    • p.T253A finding from a single family; replication in additional kindreds pending
  8. 2026 High

    Identification of SLIT2 as a direct TLL1 substrate and demonstration that furin-dependent TLL1 activation and site-specific SLIT2 cleavage are required for DRG axon fasciculation extended TLL1's function to neural development.

    Evidence Cell-based SLIT2 cleavage assay with furin inhibitor; CRISPR knock-in mice lacking the TLL1 cleavage site in Slit2 showed defective fasciculation but normal dorsal repulsion.

    PMID:41626796

    Open questions at the time
    • Whether TLL1 cleaves other axon guidance cues is unknown
    • Which protease(s) besides TLL1 contribute to SLIT2 processing in vivo not resolved

Open questions

Synthesis pass · forward-looking unresolved questions
  • The structural basis of TLL1 substrate selectivity, the full inventory of physiological substrates, and the tissue-specific regulatory mechanisms controlling TLL1 activation and dimerization remain to be defined.
  • No high-resolution crystal or cryo-EM structure of full-length TLL1 or its dimer
  • Comprehensive substrate profiling (e.g., degradomics) not performed
  • In vivo regulators of TLL1 dimerization and furin-mediated activation kinetics not characterized

Mechanism profile

Synthesis pass · controlled-vocabulary classification · explore literature graph →
Molecular activity
GO:0140096 catalytic activity, acting on a protein 6 GO:0016787 hydrolase activity 5
Localization
GO:0005576 extracellular region 3 GO:0031012 extracellular matrix 3
Pathway
R-HSA-1474244 Extracellular matrix organization 4 R-HSA-162582 Signal Transduction 3 R-HSA-1266738 Developmental Biology 2
Partners
BMP1CHRDDMP1SLIT2TGFB1

Evidence

Reading pass · 10 per-paper findings extracted from the source corpus
Year Finding Method Journal Conf PMIDs
1999 TLL1 (mTLL-1) is an astacin-like metalloprotease essential for cardiac septation; Tll1-/- mice die at mid-gestation with incomplete muscular interventricular septum formation and abnormal heart positioning, with expression specific to precardiac tissue and endocardium. Where BMP1 and TLL1 are co-expressed, BMP1 can functionally substitute for TLL1. Gene targeting/knockout in mice, in situ expression analysis, genetic epistasis Development High 10331975
2003 TLL1 (mTLL-1) cleaves Chordin in vivo (an extracellular BMP signaling antagonist) and provides residual procollagen C-proteinase (pCP) activity in Bmp1-/- embryos, demonstrating functional redundancy between BMP1 and mTLL-1 for both ECM processing and BMP signaling modulation. Bmp1/Tll1 doubly homozygous null mouse embryos, biochemical proteomics assays, cell-based substrate cleavage assays Molecular and Cellular Biology High 12808086
2009 TLL-1 forms a calcium-ion-dependent dimer with monomers stacked side-by-side, and this dimerization reduces catalytic activity toward chordin; truncated TLL-1 molecules with the same shorter domain structure as BMP-1 are monomers and have improved activity toward chordin, exceeding even BMP-1, suggesting a substrate exclusion mechanism mediated by the non-catalytic domains. Structural analysis (FEBS), truncation mutants, activity assays toward chordin substrate, biophysical characterization of dimerization FEBS Letters High 20043912
2014 Postnatal simultaneous conditional ablation of Bmp1 and Tll1 in mice causes osteogenesis imperfecta with brittle bones, spontaneous fractures, osteomalacia, reduced procollagen processing, reduced dentin matrix protein 1 (DMP1) processing, and activation of canonical Wnt signaling, demonstrating overlapping in vivo roles of BMP1 and TLL1 in procollagen and DMP1 biosynthetic processing in bone. Conditional knockout mice (floxed alleles with postnatal induction), bone histology, biomechanical testing, immunohistochemistry, Western blot for substrate processing Human Molecular Genetics High 24419319
2016 Conditional inactivation of both Bmp1 and Tll1 in type I collagen-expressing cells causes dental defects (wider predentin, thinner dentin, disorganized dentinal tubules, reduced dentin sialophosphoprotein) and disorganized periodontal ligaments with reduced fibrillin-1, demonstrating roles for TLL1 in dentin formation and periodontal ligament maintenance. Col1a1-Cre conditional double knockout mice, X-ray radiography, histology, immunohistochemistry Journal of Molecular Histology Medium 28000152
2017 Conditional double ablation of BMP1 and TLL1 in mice causes malformed periodontal ligament, alveolar bone loss, and reduced cellular cementum, associated with increased uncleaved procollagen I and reduced DMP1, and increased MMP13 and TRAP expression; systemic antibiotics partially rescue the phenotype, indicating secondary inflammatory contribution. Conditional knockout mice, histology, immunohistochemistry, μCT, antibiotic treatment rescue experiment Journal of Dental Research Medium 28068493
2022 TLL1 promotes Klebsiella pneumoniae adhesion and invasion of intestinal epithelial cells by activating the TGF-β signaling pathway; TLL1 knockdown with shRNA significantly reduced bacterial adhesion and invasion, and TGF-β pathway inhibition (SB431542) phenocopied the knockdown. shRNA knockdown in Caco-2 cells, transcriptome sequencing, TGF-β pathway inhibitor treatment, bacterial adhesion/invasion assays International Journal of Medical Microbiology Medium 36087399
2025 TLL1 cleaves latent TGF-β1 to activate TGF-β signaling, promoting prostate cancer cell migration and metastasis; TLL1 also increases PD-L1 expression via TGF-β signaling, and TLL1 depletion enhances anti-PD-1 efficacy by increasing CD8+ T cell tumor infiltration. T cell-specific TLL1 overexpression disrupts T cell development in the thymus and reduces CD8+ T cell infiltration in tumors. TLL1 knockdown/overexpression in cancer cells, mouse tumor models, flow cytometry for immune cell infiltration, TGF-β substrate cleavage assays, T cell-specific TLL1 transgenic mice Oncogene Medium 40760092
2025 A gain-of-function mutation p.T253A in the catalytic domain of TLL1 causes autosomal dominant mitral valve prolapse; the mutant TLL1 protein showed 3.4-fold higher enzymatic activity over 12 hours compared to wild-type in conditioned media of transfected HEK293 cells, indicating prolonged half-life of the active enzyme in the extracellular matrix. Whole exome/genome sequencing, Sanger sequencing for segregation, enzymatic activity assay in HEK293 cell conditioned media comparing WT vs. mutant TLL1 The Canadian Journal of Cardiology Medium 39880331
2026 TLL1 protease cleaves SLIT2 at a specific cleavage site in cultured cells, generating SLIT2-N and SLIT2-C fragments; TLL1 requires activation by furin/prohormone convertases. CRISPR editing of the TLL1 cleavage site in Slit2 (Slit2ΔTLS mice) showed that cleavage is required for DRG axon fasciculation but not for dorsal repulsion, and SLIT2-N promotes fasciculation of DRG axons in vitro. Cell-based SLIT2 cleavage assay with TLL1, CRISPR knock-in mice lacking TLL1 cleavage site (Slit2ΔTLS), furin inhibitor experiments, in vitro DRG axon fasciculation assay Development High 41626796

Source papers

Stage 0 corpus · 21 papers · ranked by NIH iCite citations
Year Title Journal Citations PMID
1999 The mammalian Tolloid-like 1 gene, Tll1, is necessary for normal septation and positioning of the heart. Development (Cambridge, England) 109 10331975
2017 Genome-Wide Association Study Identifies TLL1 Variant Associated With Development of Hepatocellular Carcinoma After Eradication of Hepatitis C Virus Infection. Gastroenterology 107 28163062
2003 Use of Bmp1/Tll1 doubly homozygous null mice and proteomics to identify and validate in vivo substrates of bone morphogenetic protein 1/tolloid-like metalloproteinases. Molecular and cellular biology 96 12808086
2014 Induced ablation of Bmp1 and Tll1 produces osteogenesis imperfecta in mice. Human molecular genetics 57 24419319
2021 PNPLA3 and TLL-1 Polymorphisms as Potential Predictors of Disease Severity in Patients With COVID-19. Frontiers in cell and developmental biology 24 34249902
2017 BMP1 and TLL1 Are Required for Maintaining Periodontal Homeostasis. Journal of dental research 23 28068493
2021 Association between Interferon-Lambda-3 rs12979860, TLL1 rs17047200 and DDR1 rs4618569 Variant Polymorphisms with the Course and Outcome of SARS-CoV-2 Patients. Genes 22 34071309
2009 Structural and functional evidence for a substrate exclusion mechanism in mammalian tolloid like-1 (TLL-1) proteinase. FEBS letters 18 20043912
2016 Inactivation of bone morphogenetic protein 1 (Bmp1) and tolloid-like 1 (Tll1) in cells expressing type I collagen leads to dental and periodontal defects in mice. Journal of molecular histology 13 28000152
2020 Possible Relevance of PNPLA3 and TLL1 Gene Polymorphisms to the Efficacy of PEG-IFN Therapy for HBV-Infected Patients. International journal of molecular sciences 11 32349377
2019 TLL1 variants do not predict hepatocellular carcinoma development in HCV cirrhotic patients treated with direct-acting antivirals. Journal of viral hepatitis 11 31177595
2022 Klebsiella pneumoniae activates the TGF-β signaling pathway to adhere to and invade intestinal epithelial cells via enhancing TLL1 expression. International journal of medical microbiology : IJMM 8 36087399
2020 Genetic variation in the TLL1 gene is not associated with fibrosis in patients with metabolic associated fatty liver disease. PloS one 7 33306709
2023 Assessment of TLL1 variant and risk of hepatocellular carcinoma in Latin Americans and Europeans. Annals of hepatology 5 37981236
2025 Mitral Valve Prolapse Caused by TLL1 Gain-of-Function Mutation. The Canadian journal of cardiology 4 39880331
2022 Deciphering complex rearrangements at the breakpoint of an apparently balanced reciprocal translocation t(4:18)(q31;q11.2)dn and at a cryptic deletion: Further evidence of TLL1 as a causative gene for atrial septal defect. American journal of medical genetics. Part A 4 35567499
2014 Association of TLL1 gene polymorphism (rs1503298, T > C) with coronary heart disease in PREDICT, UDACS and ED cohorts. Journal of the College of Physicians and Surgeons--Pakistan : JCPSP 4 25233961
2005 ASD--lessons on genetic background from transgenic mice with inactive gene encoding metalloprotease, Tolloid-like 1 (TLL1). Medical science monitor : international medical journal of experimental and clinical research 4 16369476
2025 TLL1 knockdown attenuates prostate cancer progression by enhancing antitumor immunity. Oncogene 1 40760092
2026 SLIT2 repellent is cleaved by TLL1 protease and promotes sensory axon fasciculation. Development (Cambridge, England) 0 41626796
2024 Molecular Mechanisms of Phosphate Use Efficiency in Arabidopsis via Penicillium olsonii TLL1. International journal of molecular sciences 0 39684576