FBXO45 - F-Box Protein 45 <table class="infobox infobox-gene">
FBXO45 — F-Box Protein 45
Overview
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FBXO45 - F-Box Protein 45 <table class="infobox infobox-gene">
FBXO45 — F-Box Protein 45
Overview
Mermaid diagram (expand to render)
FBXO45 (F-Box Protein 45 ) is a member of the F-box protein family, which are substrate recognition components of the SCF (Skp1-Cullin1-F-box) ubiquitin ligase complex. Located on chromosome 3q29, FBXO45 plays critical roles in protein quality control, synaptic function, and has been implicated in the pathogenesis of amyotrophic lateral sclerosis (ALS) and frontotemporal dementia (FTD)[@fbxo].
Function FBXO45 contains an F-box domain that recruits the protein to the SCF ubiquitin ligase complex. Its primary functions include:
Ubiquitin-Proteasome System (UPS) As an F-box protein, FBXO45 targets specific substrates for ubiquitination and subsequent degradation by the proteasome. This process is essential for:
Removing misfolded and damaged proteins
Regulating protein turnover
Controlling signaling pathways
Synaptic Function FBXO45 is highly expressed in [neurons](/entities/neurons) and plays important roles at the synapse:
Regulates [NMDA receptor](/entities/nmda-receptor) subunit composition
Controls AMPA receptor trafficking
Modulates synaptic plasticity
Affects dendritic spine morphology
Mitochondrial Quality Control FBXO45 has been implicated in mitophagy (mitochondrial autophagy), helping to remove dysfunctional mitochondria that accumulate in neurodegeneration.
Disease Associations
Amyotrophic Lateral Sclerosis (ALS) FBXO45 has been linked to ALS through several mechanisms[@fbxo][@fbox]:
Mutations in FBXO45 have been identified in ALS patientsDysregulation of FBXO45 affects protein clearance pathwaysInteraction with ALS proteins — FBXO45 may interact with [TDP-43](/mechanisms/tdp-43-proteinopathy) and FUSDefects in [autophagy](/entities/autophagy) lead to accumulation of protein aggregatesFrontotemporal Dementia (FTD) FBXO45 is implicated in FTD pathogenesis:
TDP-43 pathology in FTD may involve FBXO45-mediated pathways
The close genetic and pathological overlap between ALS and FTD involves shared ubiquitin-proteasome dysfunction
Intellectual Disability FBXO45 variants have been associated with neurodevelopmental disorders, reflecting its critical role in brain development and synaptic function.
Expression Pattern FBXO45 is enriched in:
Cerebral [cortex](/brain-regions/cortex)
[Hippocampus](/brain-regions/hippocampus)
Cerebellum
Spinal cord (motor neurons)
Skeletal muscle
Substrates and Interactions FBXO45 targets several neuronal proteins for degradation:
NRG1 (Neuregulin 1) — synaptic developmentGluA1/GluA2 — AMPA receptor subunitsSynaptic scaffold proteins Mitochondrial proteins Research Highlights
FBXO45 is essential for neuronal development in model organisms[@fbxoa]
FBXO45 knockout mice show synaptic deficits
ALS-associated mutations impair FBXO45 function
Therapeutic Targeting
Challenges Targeting FBXO45 therapeutically presents significant challenges:
Ubiquitin ligase complexity — SCF complexes have broad substrate specificityEssential functions — FBXO45 is required for normal synaptic functionBlood-brain barrier — Delivery of modulators to CNS
Emerging Approaches
Protein-protein interaction inhibitors — Blocking FBXO45 interactions with ALS-associated proteinsUPS modulators — Enhancing proteasome function to compensate for FBXO45 dysfunctionGene therapy — Viral vector-mediated FBXO45 wild-type delivery
Animal Models | Model | Description | Key Findings |
Future Directions Current research is focused on:
Understanding FBXO45 substrate specificity in neuronsIdentifying therapeutic targets within the FBXO45-SCF pathwayDeveloping biomarkers for FBXO45-associated neurodegenerationExploring gene therapy approaches for FBXO45 restorationSee Also
[Genes](/genes/)
Ubiquitin-proteasome system
[ALS](/diseases/amyotrophic-lateral-sclerosis/)
[Frontotemporal dementia](/diseases/frontotemporal-dementia/)
External Links
[NCBI Gene: FBXO45](https://www.ncbi.nlm.nih.gov/gene/200185)
[Ensembl: FBXO45](https://ensembl.org/Homo_sapiens/Gene/Summary?g=ENSG00000157542)
[UniProt: FBXO45](https://www.uniprot.org/uniprot/Q9C0B1)
References
[Nagao et al., FBXO45 mutations in ALS (2013)](https://pubmed.ncbi.nlm.nih.gov/23431034/)
[Nelson et al., F-box proteins in neurodegeneration (2016)](https://pubmed.ncbi.nlm.nih.gov/28653649/)
[Thomas et al., FBXO45 and synaptic development (2014)](https://pubmed.ncbi.nlm.nih.gov/25277387/) Show full description