MFAP2

MFAP2 (MAGP-2) is a secreted extracellular matrix glycoprotein that serves dual roles as a structural component of fibrillin-containing microfibrils and as a signaling modulator. It binds fibrillin-1 and fibrillin-2 via their C-terminal EGF repeat regions to promote elastic fiber assembly independently of its RGD motif (PMID:12122015, PMID:17099216), and interacts with Notch1 through its own C-terminal domain to induce ectodomain shedding and context-dependent Notch activation or antagonism—activating Notch in heterologous cells while inhibiting Notch signaling in endothelial cells to promote angiogenic sprouting (PMID:16492672, PMID:18417156). MAGP-2 also binds the Notch ligand Jagged1 and induces its metalloproteinase-dependent ectodomain shedding (PMID:15788413). In cancer contexts, secreted MFAP2 engages integrin receptors (α5β1, β4, β8) and directly binds the FERM domain of FAK to activate FAK–ERK or FAK–AKT signaling cascades that drive invasion and metastasis, and its transcription is directly activated by TWIST1 and FOXA1 (PMID:32054827, PMID:39698924, PMID:41617683, PMID:39829397).

1. 1996 High

   Identifying MAGP-2 as a distinct microfibril-associated protein established that elastin-associated microfibrils contain a second MAGP family member with divergent domain architecture and an RGD motif, raising the question of whether it has non-redundant functions relative to MAGP-1.

   Evidence cDNA cloning, immunofluorescence, and immunoelectron microscopy localizing MAGP-2 to microfibrils

   PMID:8557636

   Open questions at the time

   • No binding partners identified beyond microfibril co-localization
   • Functional significance of the RGD motif untested
   • No knockout or loss-of-function data
2. 1998 High

   Demonstrating that MAGP-2 has a more restricted tissue distribution than MAGP-1 and does not bind type VI collagen established that the two paralogs occupy distinct niches within the extracellular matrix despite their shared microfibril association.

   Evidence Immunoelectron microscopy across multiple tissues; solid-phase binding assays showing no MAGP-2–collagen VI interaction

   PMID:9278443 PMID:9671438

   Open questions at the time

   • Direct binding partner on microfibrils not yet identified
   • No functional consequence of restricted distribution tested
3. 2002 High

   Mapping the direct interaction between MAGP-2 and fibrillin-1/fibrillin-2 to a C-terminal EGF repeat region on fibrillins—distinct from the MAGP-1 binding site—revealed that the two MAGPs occupy non-overlapping sites on microfibrils, suggesting independent structural contributions.

   Evidence Yeast two-hybrid screen with deletion analysis plus co-immunoprecipitation from COS-7 cells

   PMID:12122015

   Open questions at the time

   • Functional consequence of MAGP-2–fibrillin binding for microfibril integrity not tested
   • No in vivo validation
4. 2005 High

   Discovering that MAGP-2 binds Jagged1 EGF-like repeats and induces its metalloproteinase-dependent ectodomain shedding expanded MAGP-2's role beyond structural matrix protein to a modulator of Notch ligand availability.

   Evidence Yeast two-hybrid, co-immunoprecipitation, conditioned media analysis, metalloproteinase inhibitor (BB3103)

   PMID:15788413

   Open questions at the time

   • Downstream Notch signaling consequences not measured
   • In vivo relevance of Jagged1 shedding by MAGP-2 unknown
5. 2006 High

   Two studies established that MAGP-2 directly activates Notch1 by inducing furin-dependent extracellular domain dissociation via its C-terminal domain, and independently stimulates elastic fiber assembly without requiring its RGD motif, delineating its dual structural and signaling functions.

   Evidence Co-IP with domain deletions, Notch reporter assays, ADAM inhibitor experiments; conditional MAGP-2 overexpression with electron microscopy and RGD mutant analysis

   PMID:16492672 PMID:17099216

   Open questions at the time

   • Mechanism by which MAGP-2 promotes elastin deposition without altering other matrix components unclear
   • Physiological relevance of Notch1 activation by MAGP-2 in vivo not shown
6. 2008 High

   Showing that MAGP-2 antagonizes Notch signaling specifically in endothelial cells (while activating it in other cell types) to promote angiogenic sprouting revealed that MAGP-2's effect on Notch is cell-context-dependent, resolving an apparent contradiction.

   Evidence Hes-1 reporter assay, Notch1 processing analysis, angiogenic sprouting assay with constitutively active Notch rescue in endothelial cells

   PMID:18417156

   Open questions at the time

   • Molecular basis of cell-type-specific Notch modulation not identified
   • No in vivo angiogenesis data
7. 2018 Medium

   Linking MFAP2 to epithelial-mesenchymal transition via TGF-β/SMAD2/3 signaling in gastric cancer placed it in a pro-metastatic signaling context beyond its canonical matrix and Notch roles.

   Evidence Gain- and loss-of-function experiments with SMAD2/3 phosphorylation and EMT marker analysis in gastric cancer cells

   PMID:30034240

   Open questions at the time

   • No direct MFAP2–TGF-β receptor interaction demonstrated
   • Single cancer type, single lab
8. 2020 Medium

   Identifying integrin α5β1/FAK/ERK as a direct signaling axis for MFAP2-driven gastric cancer motility, with fibronectin rescue of MFAP2 knockdown, established FAK as a central downstream effector and revealed miR-29 as an upstream regulator of MFAP2 expression.

   Evidence shRNA knockdown with fibronectin rescue, ERK signaling assays, in vivo xenograft, miRNA experiments

   PMID:32054827

   Open questions at the time

   • Direct MFAP2–integrin α5β1 physical interaction not demonstrated by co-IP
   • miR-29 regulation not validated with reporter assays in this study
9. 2020 Medium

   Demonstrating that LCPAT1 lncRNA recruits the chromatin remodeler RBBP4 to the MFAP2 promoter to activate its transcription identified a first epigenetic regulatory mechanism for MFAP2 expression.

   Evidence RNA immunoprecipitation, ChIP assay at MFAP2 promoter, MFAP2 rescue of LCPAT1 knockdown in breast cancer cells

   PMID:32791452

   Open questions at the time

   • Whether RBBP4 recruitment alters histone modifications at the MFAP2 locus not shown
   • Single cancer context
10. 2022 Medium

    Identifying CLK3 as a downstream effector whose autophagic degradation is induced upon MFAP2 depletion revealed a non-canonical intracellular consequence of extracellular MFAP2 signaling in colorectal cancer invasion.

    Evidence Mass spectrometry target screening, siRNA knockdown, CLK3 rescue, transwell invasion, peritoneal metastasis model

    PMID:36583532

    Open questions at the time

    • How an extracellular protein regulates intracellular CLK3 degradation is mechanistically unclear
    • Single lab, single cancer type
11. 2024 Medium

    Demonstrating direct MFAP2 binding to the FERM domain of FAK to relieve intramolecular autoinhibition and enhance FAK–integrin β4 interaction provided the first structural-level explanation for MFAP2-driven FAK-AKT activation in metastasis.

    Evidence Co-immunoprecipitation with domain analysis, FAK inhibitor PND-1186 in vitro and in vivo (ESCC lung metastasis model)

    PMID:39698924

    Open questions at the time

    • No crystal structure or biophysical binding data for MFAP2–FERM interaction
    • Single cancer type
12. 2025 Medium

    Identifying TWIST1 and FOXA1 as direct transcriptional activators of MFAP2 via promoter binding established upstream transcription factor control of MFAP2 in ovarian and endometrial cancers, linking EMT master regulators to MFAP2 induction.

    Evidence ChIP-qPCR and dual-luciferase reporter assays for TWIST1 and FOXA1 binding to MFAP2 promoter; gain/loss-of-function and xenograft models

    PMID:39829397 PMID:40153018

    Open questions at the time

    • Whether TWIST1 and FOXA1 cooperate or act independently at the MFAP2 promoter unknown
    • Relevance to non-cancer tissues not tested
13. 2025 Medium

    Demonstrating that cancer-associated fibroblast-secreted MFAP2 engages integrin β8 on colorectal cancer cells to activate FAK-ERK1/2-ETS2-CYP27A1 signaling, suppressing CD8+ T cell function, expanded MFAP2's role to immune evasion in the tumor microenvironment.

    Evidence Co-immunoprecipitation of MFAP2–ITGB8, phosphorylation cascade analysis, in vitro and in vivo immunosuppression experiments

    PMID:41617683

    Open questions at the time

    • Whether MFAP2–ITGB8 interaction occurs in non-tumor contexts unknown
    • Contribution relative to other CAF-derived factors not quantified

• Key unresolved questions include: the structural basis of MFAP2's context-dependent Notch modulation; in vivo phenotypes of Mfap2 genetic deletion in elastic tissue homeostasis; whether MFAP2's integrin/FAK and Notch signaling roles intersect; and the mechanism by which extracellular MFAP2 controls intracellular CLK3 degradation.
• No Mfap2 constitutive knockout phenotype in elastic tissues published in peer-reviewed literature
• Structural basis of cell-context-dependent Notch modulation unknown
• Relationship between MFAP2's matrix and signaling functions unresolved