Vitronectin (VTN) is a multifunctional extracellular matrix glycoprotein found in plasma and tissues. It plays important roles in cell adhesion, migration, and immune regulation. In the brain, vitronectin is involved in synaptic function and has been implicated in Alzheimer's disease through its interactions with [Aβ](/proteins/amyloid-beta) and its role in microglial phagocytosis.
Vitronectin (VTN) is a multifunctional extracellular matrix glycoprotein found in plasma and tissues. It plays important roles in cell adhesion, migration, and immune regulation. In the brain, vitronectin is involved in synaptic function and has been implicated in Alzheimer's disease through its interactions with [Aβ](/proteins/amyloid-beta) and its role in microglial phagocytosis.
Structure
VTN is a secreted glycoprotein:
SMT domain: Somatomedin B domain (N-terminal)
RGD sequence: Integrin-binding motif
Heparin-binding domain: C-terminal region
Hemopexin-like domain: Involved in collagen binding
VTN exists in two forms: native (single chain) and processed (two-chain form held by disulfide bonds).
Normal Function
In the nervous system:
Cell adhesion: Mediates cell-ECM adhesion via integrin binding
Synaptic function: Present at synapses, involved in synaptic organization
Wound healing: Promotes tissue repair and remodeling
Role in Neurodegeneration
Alzheimer's Disease
Accumulates in Aβ plaques
Acts as bridging molecule for Aβ-[microglia](/cell-types/microglia-neuroinflammation) interaction via integrins
Promotes Aβ aggregation in some contexts
Vitronectin fragments found in AD brain
Mediates complement activation in plaque vicinity
Molecular Mechanisms
Vitronectin's role in AD involves multiple interconnected pathways:
Aβ-VTN-integrin complex formation: VTN binds both Aβ and integrin receptors (particularly αVβ3 and αVβ5), forming a molecular bridge that facilitates Aβ internalization by microglia[@yuan2021]
Complement activation: VTN contributes to local complement cascade activation near plaques via C1q binding, enhancing neuroinflammation
Peripheral clearance: VTN-Aβ complexes can be cleared via peripheral phagocytosis, potentially serving as a sink for cerebral Aβ
Synaptic toxicity: VTN fragments interact with postsynaptic receptors, contributing to synaptic dysfunction
Vitronectin Fragments in AD
Specific VTN cleavage products have been identified in AD brain tissue:
N-terminal fragments generated by matrix metalloproteinases (MMPs)
These fragments retain integrin-binding activity but lose complement-regulatory function[@kosonen1997]
Fragment accumulation correlates with disease severity
Neuroinflammation
Regulates microglial phagocytosis via integrin signaling
Modulates complement activation
VTN polymorphisms associated with AD risk
Therapeutic Implications
Targeting vitronectin:
VTN-blocking agents to reduce Aβ plaque pathology
Modified VTN peptides for therapeutic benefit
Gene therapy approaches
Mechanism Diagram
Mermaid diagram (expand to render)
Key Publications
[Vitronectin in Aβ pathology (Duong et al., 1999)](https://doi.org/10.1016/s0301-0082(99)00038-6)[@duong1999]
[VTN and microglial phagocytosis (Zhang et al., 2020)](https://doi.org/10.3389/fncel.2020.578012)[@zhang2020]
[Vitronectin in brain physiology (Schvartz et al., 2019)](https://doi.org/10.1016/j.tcb.2019.04.001)[@schvartz2019]
[VTN and neuroinflammation in AD (Yuan et al., 2021)](https://doi.org/10.1186/s12974-021-02123-0)[@yuan2021]
[VTN accumulation in brain plaques (Kosonen et al., 1997)](https://doi.org/10.1007/s004010050685)[@kosonen1997]
[VTN in synaptic plasticity (Victor et al., 2020)](https://doi.org/10.3389/fnmol.2020.591456)[@victor2020]
Cross-References
[VTN Gene](/genes/vtn)
[Extracellular Matrix in Brain](/mechanisms/extracellular-matrix)
[Microglia in Neurodegeneration](/entities/microglia)
See Also
[Extracellular Matrix in Brain](/mechanisms/extracellular-matrix)
[Microglia in Neurodegeneration](/cell-types/microglia-neuroinflammation)