| Septin 7 | |
|---|---|
| Gene Symbol | SEPT7 |
| Full Name | Septin 7 |
| Chromosome | 7p14.3 |
| NCBI Gene ID | [317762](https://www.ncbi.nlm.nih.gov/gene/317762) |
| OMIM | 613502 |
| Ensembl ID | ENSG00000122545 |
| UniProt ID | [Q8N4M1](https://www.uniprot.org/uniprot/Q8N4M1) |
| Gene Type | Protein Coding |
| Protein Length | 447 amino acids |
| Molecular Weight | 50.8 kDa |
| Associated Diseases | Alzheimer's Disease, Parkinson's Disease, Huntington's Disease, Multiple System Atrophy, Intellectual Disability, Cancer |
SEPT7 (Septin 7) encodes an essential member of the septin family of GTP-binding proteins that serves as the central organizer of septin heterooligomeric complexes. As the largest mammalian septin at 447 amino acids, SEPT7 is unique for its ability to form homodimers and serve as the nucleating core for higher-order septin filament assembly. SEPT7 is indispensable for cytokinesis, neuronal development, synaptic function, and has been increasingly recognized in neurodegenerative disease pathogenesis[1][2].
The critical importance of SEPT7 is underscored by the fact that SEPT7 knockout is embryonic lethal in mice, highlighting its essential role in cellular function. In the brain, SEPT7 is enriched in dendritic spines, synapses, and the axon initial segment, where it regulates neuronal polarity, synaptic plasticity, and compartmentalization[3].
SEPT7 dysregulation has been implicated in multiple neurodegenerative diseases including Alzheimer's disease (interacting with tau pathology), Parkinson's disease (alpha-synuclein interactions), Huntington's disease (aggregate formation), and multiple system atrophy[4][5][6]. Additionally, SEPT7 mutations cause neurodevelopmental disorders including intellectual disability and autism spectrum disorder[7].
The SEPT7 gene is located on chromosome 7p14.3 and spans approximately 20 kb. It contains 14 exons encoding a 447-amino acid protein. The gene is evolutionarily conserved, with orthologs identified in yeast (Cdc7), Drosophila (Septin 7), and C. elegans (Septin 7 homolog). The promoter contains multiple neuronal-specific regulatory elements explaining its high brain expression.
SEPT7 shows the highest conservation among septins, reflecting its essential cellular functions. The protein contains:
This conservation makes SEPT7 a potentially valuable therapeutic target.
SEPT7 possesses distinct structural features:
Unlike other septins, SEPT7 can form homodimers. This unique property allows SEPT7 to:
The SEPT7 homodimer serves as the foundation for the canonical septin octamer (SEPT2-SEPT6-SEPT7-SEPT9)₂.
SEPT7 exhibits GTP-binding and GTPase activity essential for:
Mutations affecting GTP binding (e.g., R194H, K259M) disrupt filament formation and cause disease.
SEPT7 is essential for cytokinesis:
SEPT7 establishes and maintains cell polarity:
SEPT7 is critical for synapse formation and plasticity:
SEPT7 plays essential roles in establishing neuronal polarity:
SEPT7 regulates dendritic branching and arborization:
SEPT7 participates in axonal transport regulation:
SEPT7 plays roles in autophagy regulation:
SEPT7 influences mitochondrial dynamics in neurons:
SEPT7 is ubiquitously expressed with highest levels in:
The high brain expression reflects SEPT7's critical neuronal functions.
Within the brain, SEPT7 shows highest expression in:
In neurons, SEPT7 localizes to:
SEPT7 contributes to AD pathogenesis through multiple mechanisms:
SEPT7 interacts with tau protein and influences:
In AD brains, SEPT7 co-localizes with tau pathology, suggesting a pathogenic role[4:1].
SEPT7 plays critical roles in synaptic function that are compromised in AD:
Targeting SEPT7 in AD offers therapeutic opportunities:
In PD, SEPT7 contributes to pathogenesis through:
SEPT7 directly interacts with alpha-synuclein:
SEPT7 is highly expressed in dopaminergic neurons:
SEPT7 dysfunction in these neurons may contribute to PD pathogenesis[5:1].
SEPT7 is recruited to Huntington disease protein aggregates:
SEPT7 is implicated in MSA pathogenesis:
SEPT7 mutations cause:
These mutations disrupt neuronal development and function[7:1][11].
| Disease | Evidence Level | Proposed Mechanism |
|---|---|---|
| Alzheimer's Disease | Strong | Tau interaction, synaptic dysfunction |
| Parkinson's Disease | Strong | Alpha-synuclein interaction, Lewy body formation |
| Huntington's Disease | Moderate | Aggregate formation |
| Multiple System Atropy | Moderate | Inclusion formation |
| Intellectual Disability | Strong | Impaired neuronal development |
| Cancer | Strong | Altered cytokinesis |
| Protein | Interaction Type | Functional Relevance |
|---|---|---|
| SEPT2 | Complex formation | Filament assembly |
| SEPT6 | Complex formation | Filament assembly |
| SEPT9 | Complex formation | Filament assembly |
| SEPT11 | Complex formation | Higher-order assembly |
| SEPT7 | Homodimerization | Nucleation of assembly |
| Tau | Binding | Tau pathology in AD |
| Alpha-synuclein | Binding | Lewy body formation |
| PSD-95 | Binding | Synaptic localization |
| NMDA receptor | Binding | Synaptic plasticity |
| AMPA receptor | Binding | Synaptic transmission |
| Synapsin | Binding | Synaptic vesicle organization |
| Huntingtin | Binding | HD aggregate formation |
SEPT7 levels in cerebrospinal fluid may serve as biomarker for neurodegenerative disease progression.
SEPT7 exhibits high expression in the human brain based on Allen Human Brain Atlas data. Strong expression is observed throughout the cerebral cortex, particularly in pyramidal neurons, and in the hippocampus. The cerebellum shows particularly high SEPT7 expression in Purkinje cells. Single-cell expression data from the Allen Brain Cell Atlas indicates SEPT7 is expressed in most neuronal populations including excitatory pyramidal neurons, inhibitory interneurons, and some glial cells. This broad neuronal expression pattern supports SEPT7's essential roles in synaptic function and its relevance to neurodegenerative diseases affecting multiple brain regions.
Resources:
SEPT7 knockout is embryonic lethal, demonstrating its essential nature. Conditional knockout in neurons shows:
Transgenic mice expressing mutant SEPT7 recapitulate:
Xie Y et al. SEPT7 in neuronal development and polarity. 2008. ↩︎
Mostowy S et al. Septins in disease: from infection to cancer. 2010. ↩︎
Ageta-Ishihara N et al. SEPT7 is required for synapse formation and plasticity. 2013. ↩︎ ↩︎
Taylor E et al. SEPT7 and tau pathology in Alzheimer's disease. 2020. ↩︎ ↩︎
Robinson RA et al. SEPT7 dysfunction in Parkinson's disease models. 2021. ↩︎ ↩︎
Kim M et al. SEPT7 in multiple system atrophy pathogenesis. 2023. ↩︎ ↩︎
Hu J et al. SEPT7 in cortical development and intellectual disability. 2018. ↩︎ ↩︎
Patel S et al. SEPT7 and autophagy in neurodegeneration. 2022. ↩︎
Wang J et al. SEPT7 and mitochondrial function in neurons. 2023. ↩︎
Hernandez A et al. SEPT7 in Huntington's disease protein aggregates. 2024. ↩︎
Yang L et al. SEPT7 variants in neurodevelopmental disorders. 2023. ↩︎