ADAMTSL1

ADAMTSL1 (punctin) is a secreted, hatchet-shaped extracellular matrix glycoprotein built from four thrombospondin type I repeats but lacking the metalloprotease and disintegrin-like domains of catalytic ADAMTS family members, and it is deposited in a punctate pattern into the cell substratum (PMID:11805097). Its secretion is governed by post-translational modification: C-mannosylation of Trp42 within a W-x-x-W motif is required for proper folding and export, and the disease-associated p.Trp42Arg substitution abolishes secretion, causing intracellular retention and a dominant-negative reduction in secretion of co-expressed wild-type protein (PMID:28722276). Its thrombospondin repeats additionally carry the glucose-β1,3-fucose disaccharide added by B3GLCT (PMID:18720094), and the mature protein is a direct proteolytic substrate of MMP10 (PMID:24281761), placing ADAMTSL1 within a regulated ECM remodeling context. Functionally, the C. elegans ortholog MADD-4 acts as a secreted UNC-40/DCC-dependent midline guidance cue, implicating the family in nervous system patterning (PMID:22014523), while in mammals ADAMTSL1 marks a Pmp2+ myelinating Schwann cell subtype that ensheathes large-caliber motor axons (PMID:35115729). ADAMTSL1 expression is also responsive to Hedgehog signaling and modulates chondrosarcoma proliferation (PMID:24634412). Direct biochemical demonstration of an enzymatic activity for the mammalian protein has not been established in the available corpus.

1. 2002 High

   Established the molecular identity of ADAMTSL1 as a secreted ADAMTS-like glycoprotein, defining it as a non-catalytic ECM component rather than a protease.

   Evidence Insect-cell expression, purification, Edman/MS sequencing, glycopeptide analysis, rotary-shadowing EM, and COS-1 transfection immunofluorescence

   PMID:11805097

   Open questions at the time

   • No binding partners or ECM ligands identified
   • No enzymatic activity or function assigned
2. 2009 Medium

   Defined a specific glycan signature on the TSRs, linking ADAMTSL1 to the B3GLCT glycosylation pathway implicated in Peters'-plus syndrome.

   Evidence Biochemical demonstration of glucose-β1,3-fucose disaccharide on purified protein plus genetic linkage of B3GLCT

   PMID:18720094

   Open questions at the time

   • Functional consequence of the modification for ADAMTSL1 not tested
   • No direct ADAMTSL1 phenotype in Peters'-plus established
3. 2011 Medium

   Assigned the ADAMTSL family a guidance function by showing the ortholog acts as a secreted directional cue dependent on a netrin receptor.

   Evidence Genetic loss-of-function, rescue, and cell-autonomous epistasis with unc-40/DCC in C. elegans (MADD-4)

   PMID:22014523

   Open questions at the time

   • Mammalian ADAMTSL1 guidance function not directly tested
   • Molecular mechanism of UNC-40 cooperation unresolved
4. 2013 Medium

   Identified ADAMTSL1 as a regulated proteolytic substrate, placing it within active ECM remodeling.

   Evidence TAILS N-terminomics degradomics on MMP10-treated fibroblast secretomes

   PMID:24281761

   Open questions at the time

   • Cleavage site and biological consequence of MMP10 processing not characterized
   • Single-lab degradomic screen without orthogonal in vivo confirmation
5. 2014 Medium

   Linked ADAMTSL1 to a signaling pathway and a proliferative phenotype, suggesting a role downstream of Hedgehog in tumor growth.

   Evidence Expression profiling of IPI-926-treated chondrosarcoma xenografts plus proliferation assays

   PMID:24634412

   Open questions at the time

   • Mechanism connecting Hh signaling to ADAMTSL1 unresolved
   • Limited mechanistic detail on how ADAMTSL1 affects proliferation
6. 2017 High

   Established that a single Trp residue controls ADAMTSL1 secretion and that its disruption acts dominant-negatively, providing a disease-relevant mechanism.

   Evidence WT vs p.Trp42Arg secretion assays, co-transfection dominant-negative test, and three-generation pedigree cosegregation

   PMID:28722276

   Open questions at the time

   • Disease phenotype caused by the variant not detailed mechanistically
   • Downstream ECM consequence of retained protein not defined
7. 2019 Low

   Connected ADAMTSL1 variants to a tissue-specific skeletal phenotype, implicating it in mandibular condylar cartilage growth.

   Evidence Whole-exome sequencing, cosegregation in Thai families, and in situ expression in mouse condyle

   PMID:30714143

   Open questions at the time

   • Proposed aggrecan-cleavage mechanism not experimentally confirmed
   • Functional consequence of the variants untested
8. 2022 Medium

   Identified ADAMTSL1 as a marker of a Schwann cell subtype specialized for large-caliber motor axons and relevant to ALS.

   Evidence Single-nucleus RNA-seq of mouse nerve, immunostaining validation, comparison to SOD1G93A and human ALS tissue

   PMID:35115729

   Open questions at the time

   • ADAMTSL1 used as a marker, not functionally manipulated
   • Causal role of ADAMTSL1 in the SC subtype unestablished
9. 2025 Medium

   Demonstrated the physiological importance of the ADAMTSL1-marked Schwann cell population for motor axon maintenance and its reversibility.

   Evidence Inducible Pmp2-CreERT2/iDTR ablation with behavioral, electrophysiological, and EM ultrastructural readouts

   PMID:39880678

   Open questions at the time

   • ADAMTSL1 is a co-marker of the ablated cells, not the manipulated molecule
   • Direct contribution of ADAMTSL1 protein to axon support not isolated

• Whether mammalian ADAMTSL1 has a defined ECM ligand, receptor, or biochemical activity that mediates its roles in neural guidance and connective tissue regulation remains unresolved.
• No direct mammalian binding partner or substrate identified
• No structural model beyond rotary-shadowing morphology
• Functional link between glycosylation/cleavage and downstream phenotypes unestablished