The HOMER3 gene (Homer Scaffold Protein 3) encodes a member of the Homer family of postsynaptic density (PSD) scaffold proteins. HOMER3 plays critical roles in synapse formation, synaptic plasticity, and neuronal signaling by linking metabotropic glutamate receptors (mGluRs) to intracellular signaling pathways and the actin cytoskeleton. Dysregulation of HOMER proteins is implicated in various neurological disorders including Alzheimer's disease, schizophrenia, and autism spectrum disorders.
| Attribute |
Value |
| Symbol |
HOMER3 |
| Full Name |
Homer Scaffold Protein 3 |
| Chromosomal Location |
19p13.11 |
| NCBI Gene ID |
84524 |
| OMIM ID |
604001 |
| Ensembl ID |
ENSG00000150773 |
| UniProt ID |
Q9NKUC6 |
| Protein Size |
354 amino acids |
| Molecular Weight |
~40 kDa |
HOMER proteins contain two main functional domains:
- N-terminal Ena/VASP Homology 1 (EVH1) domain: Binds to proline-rich motifs in target proteins, particularly the PPXXF motif found in mGluRs and IP3 receptors
- C-terminal Coiled-Coil (CC) domain: Enables Homer multimerization
- HOMER3a: Full-length form, predominant in brain
- HOMER3b: Shorter variant with different expression pattern
HOMER3 is a core component of the postsynaptic density:
- mGluR Anchoring: Binds to group I mGluRs (mGluR1/5), positioning them at synaptic sites
- IP3 Receptor Linking: Connects mGluR signaling to calcium release from intracellular stores
- PSD Protein Interactions: Associates with PSD-95, Shank, and other scaffold proteins
- Long-term Depression (LTD): Critical for mGluR-dependent LTD
- Calcium Signaling: Modulates intracellular calcium dynamics
- Actin Cytoskeleton: Links signaling to actin remodeling at synapses
- Spine Formation: Promotes dendritic spine development
- Spine Maintenance: Stabilizes spine structure
- Synaptic Transmission: Regulates excitatory neurotransmission
HOMER3 is primarily expressed in the brain:
- Cerebral cortex (layers II-VI, pyramidal neurons)
- Hippocampus (CA1-CA3 pyramidal cells, dentate gyrus)
- Cerebellum (Purkinje cells)
- Striatum (medium spiny neurons)
- Olfactory bulb
Expression is development-regulated, increasing during postnatal brain development.
- Synaptic Loss: HOMER3 downregulation contributes to synaptic dysfunction
- mGluR Signaling: Altered mGluR5 signaling in AD models
- Cognitive Decline: Linked to memory deficits
- Genetic Associations: HOMER3 variants associated with risk
- Synaptic Dysfunction: Altered expression in postmortem brain
- ** glutamate Hypothesis**: Links to glutamatergic dysfunction
- Synaptic Protein Interactions: Affected in some ASD cases
- Synaptic Plasticity: May contribute to circuit abnormalities
- Seizure Activity: HOMER3 expression altered in epileptic brain
- Network Excitability: Modulates neuronal excitability
HOMER3 integrates multiple signaling pathways:
- mGluR1/5 Signaling: Downstream of group I metabotropic glutamate receptors
- PI3K/Akt Pathway: Cell survival signaling
- MAPK/ERK Pathway: Synaptic plasticity and gene expression
- Calcium Signaling: IP3 receptor-mediated calcium release
HOMER3 interacts with:
| Protein |
Interaction Type |
Function |
| mGluR1/5 |
Direct binding |
Receptor anchoring |
| IP3R1 |
Direct binding |
Calcium signaling |
| PSD-95 |
Indirect |
PSD organization |
| Shank |
Indirect |
Spine structure |
| Rheb |
Direct binding |
mTOR signaling |
- Homer1 knockout mice show impaired mGluR-dependent LTD
- Overexpression of HOMER3 enhances synaptic stability
- Viral delivery of HOMER vectors improves synaptic function in models