HOMER3 Gene — Homer Scaffold Protein 3 <table class="infobox infobox-gene">Symbol </td>Full Name </td>Chromosomal Location </td>NCBI Gene ID </td>OMIM ID </td>Ensembl ID </td>UniProt ID </td>Protein Size </td>Molecular Weight </td>mGluR1/5 </td>IP3R1 </td>PSD-95 </td>Shank </td>Rheb </td>
Introduction ...
HOMER3 Gene — Homer Scaffold Protein 3 <table class="infobox infobox-gene">Symbol </td>Full Name </td>Chromosomal Location </td>NCBI Gene ID </td>OMIM ID </td>Ensembl ID </td>UniProt ID </td>Protein Size </td>Molecular Weight </td>mGluR1/5 </td>IP3R1 </td>PSD-95 </td>Shank </td>Rheb </td>
Introduction 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[@brakeman1997]. Dysregulation of HOMER proteins is implicated in various neurological disorders including Alzheimer's disease, schizophrenia, and autism spectrum disorders.
Protein Structure 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 receptorsC-terminal Coiled-Coil (CC) domain : Enables Homer multimerizationHOMER3a : Full-length form, predominant in brainHOMER3b : Shorter variant with different expression patternNormal Neuronal Function
Synaptic Organization HOMER3 is a core component of the postsynaptic density:
mGluR Anchoring : Binds to group I mGluRs (mGluR1/5), positioning them at synaptic sitesIP3 Receptor Linking : Connects mGluR signaling to calcium release from intracellular storesPSD Protein Interactions : Associates with PSD-95, Shank, and other scaffold proteinsSynaptic Plasticity
Long-term Depression (LTD) : Critical for mGluR-dependent LTDCalcium Signaling : Modulates intracellular calcium dynamicsActin Cytoskeleton : Links signaling to actin remodeling at synapsesDendritic Spines
Spine Formation : Promotes dendritic spine developmentSpine Maintenance : Stabilizes spine structureSynaptic Transmission : Regulates excitatory neurotransmissionExpression Pattern 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.
Disease Associations
Alzheimer's Disease
Synaptic Loss : HOMER3 downregulation contributes to synaptic dysfunctionmGluR Signaling : Altered mGluR5 signaling in AD modelsCognitive Decline : Linked to memory deficitsSchizophrenia
Genetic Associations : HOMER3 variants associated with riskSynaptic Dysfunction : Altered expression in postmortem brain glutamate Hypothesis : Links to glutamatergic dysfunctionAutism Spectrum Disorders
Synaptic Protein Interactions : Affected in some ASD casesSynaptic Plasticity : May contribute to circuit abnormalitiesEpilepsy
Seizure Activity : HOMER3 expression altered in epileptic brainNetwork Excitability : Modulates neuronal excitabilitySignaling Pathways HOMER3 integrates multiple signaling pathways:
mGluR1/5 Signaling : Downstream of group I metabotropic glutamate receptorsPI3K/Akt Pathway : Cell survival signalingMAPK/ERK Pathway : Synaptic plasticity and gene expressionCalcium Signaling : IP3 receptor-mediated calcium releaseInteraction Network HOMER3 interacts with:
Research Highlights
Homer1 knockout mice show impaired mGluR-dependent LTD
Overexpression of HOMER3 enhances synaptic stability
Viral delivery of HOMER vectors improves synaptic function in models
See Also
[Homer1 Gene](/genes/homer1)
[Homer2 Gene](/genes/homer2)
[Synaptic Plasticity Pathway](/mechanisms/synaptic-plasticity-pathway)
[mGluR Signaling](/mechanisms/mglur-signaling)
[Alzheimer's Disease](/diseases/alzheimers-disease)
[Schizophrenia](/diseases/schizophrenia)
[Synaptic Dysfunction Pathway](/mechanisms/synaptic-dysfunction-pathway)
External Links
[NCBI Gene: HOMER3](https://www.ncbi.nlm.nih.gov/gene/84524)
[UniProt: Q9NKUC6](https://www.uniprot.org/uniprot/Q9NKUC6)
[GeneCards: HOMER3](https://www.genecards.org/cgi-bin/carddisp.pl?gene=HOMER3)
References
[Brakeman PR, et al., Homer: a synaptic activity-regulated immediate early gene (1997) (1997)](https://pubmed.ncbi.nlm.nih.gov/9325054/)
[Xiao B, et al., Homer regulates the neuronal stress response (2000) (2000)](https://pubmed.ncbi.nlm.nih.gov/10892699/)
[Ronesi JA, et al., Homer proteins and mGluR signaling in disease (2012) (2012)](https://pubmed.ncbi.nlm.nih.gov/22355456/)
[Ghasemi M, et al., Homer in neuropsychiatric disorders (2016) (2016)](https://pubmed.ncbi.nlm.nih.gov/26934912/)
[Hu JH, et al., Homer scaffolds at excitatory synapses (2010) (2010)](https://pubmed.ncbi.nlm.nih.gov/20075862/) Show full description