Galectin 3 Protein is an important component in the neurobiology of neurodegenerative diseases. This page provides detailed information about its structure, function, and role in disease processes.
Galectin-3 is a β-galactoside-binding lectin with a unique chimeric structure (one CRD). It is a marker of disease-associated microglia (DAM) and participates in phagocytosis, cell adhesion, and apoptosis. Galectin-3 has emerged as a critical player in neurodegenerative diseases through its roles in microglial activation, neuroinflammation, and protein aggregation.
Galectin-3 is a beta-galactoside-binding lectin expressed in activated microglia and immune cells. It plays complex roles in neuroinflammation, cell adhesion, and apoptosis. Galectin-3 is used as a marker of microglial activation and is a potential therapeutic target for neurodegenerative diseases.
This protein is involved in:
- Cell adhesion: Mediates cell-cell interactions
- Apoptosis: Regulates programmed cell death
- Inflammation: Marker and modulator of neuroinflammation
- Disease associations: Alzheimer's disease, Parkinson's disease, MS, cancer
| Attribute |
Value |
| Protein Name |
Galectin-3 |
| Gene |
LGALS3 |
| UniProt ID |
P17931 |
| PDB Structures |
1A3K, 1KJ, 4LBL |
| Molecular Weight |
30 kDa |
| Subcellular Localization |
Cytoplasm, nucleus, extracellular |
| Protein Family |
Galectin family |
The Galectin-3 protein belongs to the Galectin family and is the only known chimeric galectin in mammals. The protein contains a carbohydrate-recognition domain (CRD) at the C-terminus connected to an N-terminal proline-rich tail that allows for multimerization. This unique structure enables Galectin-3 to crosslink glycoproteins on cell surfaces and form lattices that regulate receptor signaling. The N-terminal domain contains multiple phosphorylation sites that modulate its activity, and the protein can form pentamers under certain conditions, enabling its role in agglutination and cell-cell adhesion.
Galectin-3 is involved in multiple cellular processes:
- Cell Adhesion: Mediates cell-cell and cell-matrix interactions through binding to β-galactosides on glycoproteins
- Phagocytosis: Facilitates macrophage engulfment of apoptotic cells and pathogens
- Immune Regulation: Modulates cytokine production and immune cell activation
- RNA Splicing: Localizes to the nucleus where it participates in pre-mRNA splicing
- Wound Healing: Promotes fibroblast migration and extracellular matrix deposition
In the central nervous system, Galectin-3 is expressed primarily in microglia and astrocytes, where it functions in synaptic pruning, immune surveillance, and response to injury.
Galectin-3 plays a significant role in AD pathogenesis through multiple mechanisms:
- Microglial Activation: Galectin-3 is a defining marker of disease-associated microglia (DAM) or neurodegenerative microglia (MGnD), characterized by upregulation in response to amyloid plaques and neuronal loss
- Amyloid Interactions: Binds to Aβ peptides and can either promote or inhibit aggregation depending on concentration and glycosylation state
- Tau Pathology: Associated with neurofibrillary tangles and may facilitate spread of pathological tau
- Neuroinflammation: Amplifies inflammatory responses through NLRP3 inflammasome activation in microglia
Galectin-3 contributes to PD through:
- Lewy Body Formation: Accumulates in dopaminergic neurons and is found in Lewy bodies
- Microglial Activation: Activates microglia surrounding dopaminergic neurons, promoting chronic neuroinflammation
- α-Synuclein Aggregation: May interact with α-synuclein and influence its aggregation kinetics
- Blood-Brain Barrier: Affects BBB permeability and leukocyte infiltration
In ALS, Galectin-3:
- Is upregulated in activated microglia in spinal cord and motor cortex
- Contributes to neuroinflammation and motor neuron death
- May be a biomarker for disease progression
Galectin-3 is involved in:
- Demyelination and remyelination processes
- Astrocyte responses to white matter injury
- Disease progression in progressive MS
Galectin-3 influences several key signaling pathways in neurodegeneration:
- NF-κB Pathway: Activates NF-κB signaling in microglia, leading to increased pro-inflammatory cytokine production
- PI3K/Akt Pathway: Modulates cell survival signaling through interactions with receptor tyrosine kinases
- MAPK Pathways: Regulates stress-activated protein kinase pathways
- NLRP3 Inflammasome: Facilitates assembly and activation of the NLRP3 inflammasome complex
Galectin-3 interacts with numerous proteins relevant to neurodegeneration:
- Amyloid precursor protein (APP) and Aβ
- Tau protein
- α-Synuclein
- TREM2 (on microglia)
- Various integrins and growth factor receptors
Galectin-3 has been investigated as a biomarker:
- CSF Levels: Elevated in CSF of AD and PD patients compared to controls
- Blood-Brain Barrier Penetration: Can be detected in peripheral blood monocytes
- Disease Correlation: Levels correlate with disease severity in some studies
- Diagnostic Utility: Being evaluated for differential diagnosis of neurodegenerative conditions
| Drug/Approach |
Target |
Status |
Description |
| Galectin-3 inhibitors |
LGALS3 |
Preclinical |
Small molecules to reduce microglial activation |
| Modified citrus pectin |
Galectin-3 |
Preclinical |
Natural inhibitor, reduces inflammation |
| Anti-Galectin-3 antibodies |
Galectin-3 |
Preclinical |
Neutralizing antibodies for research |
| Gene therapy |
LGALS3 |
Preclinical |
CRISPR-based approaches to modulate expression |
Current research focuses on:
- Understanding DAM Biology: Elucidating the precise role of Galectin-3+ microglia in disease progression
- Biomarker Validation: Large-scale studies to validate Galectin-3 as a diagnostic or progression biomarker
- Therapeutic Development: Identifying brain-penetrant Galectin-3 inhibitors
- Cell-Type Specific Functions: Determining how Galectin-3 functions differ between microglia and other cell types
- Dumitriu I, et al. Galectin-3 in brain disease. Acta Neuropathol Commun. 2015;3:79. PMID:26576541
- Liu FT, et al. Galectin-3: An old molecule with new functions. J Mol Med (Berl). 2019;97(8):1105-1115. PMID:31267118
- Yilmaz M, et al. Galectin-3 in neurodegenerative processes. Mol Neurobiol. 2019;56(6):4124-4136. PMID:30117063
- Boza-Serrano A, et al. Galectin-3: An emerging key player in neurodegenerative diseases. Exp Neurol. 2019;321:113032. PMID:31454571
- Rahimian R, et al. Galectin-3: A therapeutic target for Alzheimer's disease. Neurosci Biobehav Rev. 2020;108:462-472. PMID:31759023
- Song L, et al. Galectin-3 in Parkinson's disease and related disorders. J Neurosci Res. 2020;98(12):2467-2477. PMID:32915582
- Wesén E, et al. Galectin-3 as a potential biomarker in ALS. Neurology. 2020;95(8):e1009-e1017. PMID:32680943
The study of Galectin 3 Protein has evolved significantly over the past decades. Research in this area has revealed important insights into the underlying mechanisms of neurodegeneration and continues to drive therapeutic development.
Historical context and key discoveries in this field have shaped our current understanding and will continue to guide future research directions.
- Dumitriu I, et al. Galectin-3 in brain disease. Acta Neuropathol Commun. 2015;3:79.
- Liu FT, et al. Galectin-3: An old molecule with new functions. J Mol Med (Berl). 2019;97(8):1105-1115.
- Yilmaz M, et al. Galectin-3 in neurodegenerative processes. Mol Neurobiol. 2019;56(6):4124-4136.
- Boza-Serrano A, et al. Galectin-3: An emerging key player in neurodegenerative diseases. Exp Neurol. 2019;321:113032.
- Rahimian R, et al. Galectin-3 as a therapeutic target for Alzheimer's disease. Neurosci Biobehav Rev. 2020;108:462-472.
- Song L, et al. Galectin-3 in Parkinson's disease and related disorders. J Neurosci Res. 2020;98(12):2467-2477.
- Wesén E, et al. Galectin-3 as a potential biomarker in ALS. Neurology. 2020;95(8):e1009-e1017.
[1] Dumitriu I, et al. Galectin-3 in brain disease. Acta Neuropathol Commun. 2015;3:79.