SEPTIN6 Gene

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SEPTIN6 Gene

<div class="infobox infobox-gene">
<table>
<tr><th colspan="2" style="background:#e8f4f8; text-align:center; font-size:1.1em;">Septin 6</th></tr>
<tr><td>Gene Symbol</td><td>SEPTIN6</td></tr>
<tr><td>Full Name</td><td>Septin 6</td></tr>
<tr><td>Aliases</td><td>SEPT6, KIAA0128</td></tr>
<tr><td>Chromosome</td><td>Xq24</td></tr>
<tr><td>NCBI Gene ID</td><td>[23157](https://www.ncbi.nlm.nih.gov/gene/23157)</td></tr>
<tr><td>OMIM</td><td>300503</td></tr>
<tr><td>Ensembl ID</td><td>ENSG00000125354</td></tr>
<tr><td>UniProt ID</td><td>[Q9NRF8](https://www.uniprot.org/uniprot/Q9NRF8)</td></tr>
<tr><td>Gene Type</td><td>Protein Coding</td></tr>
<tr><td>Protein Length</td><td>410 amino acids</td></tr>
<tr><td>Molecular Weight</td><td>46.2 kDa</td></tr>
<tr><td>Associated Diseases</td><td>Alzheimer's Disease, Parkinson's Disease, Huntington's Disease, ALS, Cancer, Intellectual Disability</td></tr>
</table>
</div>

Introduction

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SEPTIN6 Gene

Introduction

SEPTIN6 (Septin 6), also known as SEPT6 or KIAA0128, is a critical member of the septin GTP-binding protein family that plays essential roles in cytokinesis, cellular organization, and neuronal function. As an X-linked septin, SEPTIN6 forms heterooligomeric complexes with other septins, particularly SEPT2, SEPT7, and SEPT9, to create filamentous structures that serve as diffusion barriers, scaffolds, and organizers of cellular compartments[@kinoshita2003][@sellin2011].

SEPTIN6 is ubiquitously expressed with particularly high levels in the brain, where it localizes to synaptic terminals, [dendritic spines](/mechanisms/dendritic-spines), and various neuronal compartments. It has been increasingly recognized as a player in neurodegenerative disease pathogenesis, with roles in [Alzheimer's disease](/diseases/alzheimers-disease), [Parkinson's disease](/diseases/parkinsons-disease), and other neurodegenerative conditions[@baba2019].

The protein's involvement in synaptic vesicle clustering, axonal transport, and dendritic spine morphogenesis highlights its importance in maintaining neuronal function. Additionally, SEPTIN6's role in protein aggregation diseases and its interaction with disease-associated proteins make it a subject of increasing research interest.

Gene Structure and Evolution

Genomic Organization

The SEPTIN6 gene is located on the X chromosome at Xq24 and spans approximately 12 kb. It contains 11 exons encoding a 410-amino acid protein. The gene is conserved across mammals, with orthologs identified in mouse, rat, and other vertebrates. The X-linked nature of SEPTIN6 means that hemizygous males express only one allele, potentially influencing disease susceptibility.

Evolutionary Conservation

SEPTIN6 shows moderate conservation among septins, with the GTP-binding domain being most conserved. Phylogenetic analysis groups SEPTIN6 with SEPT2, SEPT7, and SEPT9 in a subfamily that forms the core of septin heterooligomers.

Protein Structure and Biochemistry

Domain Architecture

SEPTIN6 possesses the canonical septin domain structure:

N-terminal variable region (amino acids 1-70): Contains regulatory sequences

GTP-binding domain (amino acids 71-250): Conserved P-loop NTP hydrolase

Switch I and II regions: Conformational changes controlling GTP/GDP cycling

C-terminal coiled-coil domain (amino acids 280-410): Mediates protein-protein interactions

GTP Binding and Hydrolysis

SEPTIN6 exhibits GTP-binding and GTPase activity essential for:

Septin filament assembly
Protein complex formation
Cellular localization dynamics

The GTP-bound state promotes septin polymerization, while GTP hydrolysis triggers disassembly and recycling of septin complexes[@toth2012].

Higher-Order Assembly

SEPTIN6 forms heterooligomeric complexes with other septins:

Typically forms trimeric or tetrameric complexes
Co-assembles with SEPT2, SEPT7, and SEPT9
Further assembles into filaments and higher-order structures
Creates diffusion barriers in cellular compartments

Biological Functions

Cellular Functions

Cytokinesis

SEPTIN6 plays essential roles in cytokinesis:

Localizes to the contractile ring during cell division
Forms the diffusion barrier at the cleavage furrow
Ensures proper chromosome segregation
Prevents mixing of daughter cell components

Membrane Domain Organization

SEPTIN6 organizes specialized membrane domains:

Creates diffusion barriers between cellular compartments
Maintains polarity domains
Organizes specialized membrane regions

Neuronal Functions

Synaptic Vesicle Clustering

In presynaptic terminals, SEPTIN6:

Organizes synaptic vesicle pools
Clusters vesicles at active zones
Regulates vesicle availability for release
Modulates release probability[@moon2014]

Dendritic Spine Morphogenesis

SEPTIN6 contributes to [dendritic spine](/mechanisms/dendritic-spines) development:

Controls spine formation during development
Maintains spine stability
Regulates spine head morphology
Affects postsynaptic density organization

Axonal Transport

SEPTIN6 participates in axonal transport:

Associates with transport vesicles
Regulates cargo movement along microtubules
Influences distribution of synaptic proteins

Neurotransmitter Release

SEPTIN6 modulates neurotransmitter release:

Interacts with SNARE complex proteins
Regulates vesicle fusion kinetics
Affects short-term plasticity

Studies show SEPTIN6 knockdown reduces evoked excitatory postsynaptic currents[@patel2020].

Signaling Pathways

SEPTIN6 participates in several signaling cascades:

MAPK signaling: Modulates MAP kinase pathways
PI3K/Akt pathway: Affects cell survival signaling
Calcium signaling: Modulates calcium-dependent processes

Expression Pattern

Tissue Distribution

SEPTIN6 is expressed in most tissues:

Brain: Highest expression in neurons
Hematopoietic cells: Present in various blood cell types
Epithelial tissues: Moderate expression in polarized epithelia
Proliferating cells: Upregulated during cell division

Brain Expression

In the brain, SEPTIN6 shows high expression in:

Cerebral [cortex](/brain-regions/cortex) (layers V-VI)
[Hippocampus](/brain-regions/hippocampus) (CA1-CA3)
Cerebellum (Purkinje cells)
Striatum

Cellular Localization

In neurons, SEPTIN6 localizes to:

Synaptic terminals (presynaptic active zones)
Axons and dendrites
[Dendritic spines](/mechanisms/dendritic-spines)
Golgi apparatus

Role in Neurodegenerative Diseases

Alzheimer's Disease

SEPTIN6 dysregulation contributes to AD pathogenesis through multiple mechanisms:

Synaptic Pathology

SEPTIN6 plays critical roles in synaptic function that are compromised in AD:

Loss of SEPTIN6 from synapses correlates with cognitive decline
Altered septin organization in AD synapses contributes to dysfunction
SEPTIN6 regulates synaptic vesicle pools that are depleted in AD

Tau Pathology

SEPTIN6 may interact with [tau](/proteins/tau) phosphorylation pathways:

Co-localizes with neurofibrillary tangles in some cases
May influence tau aggregation
Could affect tau spreading between neurons[@kim2022]

Amyloid Interaction

[A-beta](/proteins/amyloid-beta) affects SEPTIN6 dynamics:

A-beta oligomers alter septin localization
May disrupt SEPTIN6-containing diffusion barriers
Contributes to synaptic dysfunction

Parkinson's Disease

In PD, SEPTIN6 contributes to:

Alpha-Synuclein Interactions

SEPTIN6 interacts with [alpha-synuclein](/proteins/alpha-synuclein):

May be recruited to Lewy bodies
Could influence aggregation dynamics
May contribute to synaptic dysfunction[@suzuki2024]

Mitochondrial Dysfunction

SEPTIN6 affects mitochondrial pathways:

May influence mitochondrial dynamics
Could affect energy metabolism in neurons
Contributes to dopaminergic neuron vulnerability

Autophagy Regulation

SEPTIN6 participates in [autophagy](/entities/autophagy):

Regulates protein aggregate clearance
Dysfunction leads to accumulation of aggregates
Contributes to neurodegeneration

Huntington's Disease

SEPTIN6 is implicated in HD:

Recruited to mutant huntingtin aggregates
Contributes to aggregate formation
May sequester functional SEPTIN6

Amyotrophic Lateral Sclerosis

SEPTIN6 has been implicated in ALS:

Detected in motor neuron inclusions
May contribute to protein aggregate formation
Could affect motor neuron function

Disease Associations

| Disease | Evidence Level | Proposed Mechanism |
|---------|----------------|-------------------|
| Alzheimer's Disease | Strong | Synaptic dysfunction, tau interaction |
| Parkinson's Disease | Moderate | Alpha-synuclein interaction |
| Huntington's Disease | Moderate | Aggregate formation |
| ALS | Moderate | Motor neuron protein aggregates |
| Cancer | Strong | Altered cytokinesis |
| Intellectual Disability | Moderate | Impaired neuronal development |

Interacting Partners

| Protein | Interaction Type | Functional Relevance |
|---------|------------------|----------------------|
| SEPT2 | Complex formation | Filament assembly |
| SEPT7 | Complex formation | Filament assembly |
| SEPT9 | Complex formation | Filament assembly |
| Syntaxin | Binding | Synaptic function regulation |
| SNARE proteins | Interaction | Exocytosis control |
| Actin | Binding | Cytoskeletal organization |
| Microtubules | Binding | Transport regulation |
| Tau | Binding | AD pathology |
| Alpha-synuclein | Binding | PD pathology |

Therapeutic Implications

Therapeutic Targets

Septin filament modulators: Compounds affecting SEPTIN6 assembly

GTPase activity modulators: Targeting SEPTIN6 GTP binding

Protein interaction inhibitors: Blocking pathogenic interactions

Gene expression modulators: Regulating SEPTIN6 levels

Biomarker Potential

SEPTIN6 in cerebrospinal fluid may serve as:

Disease progression marker
Treatment response indicator
Diagnostic tool for neurodegeneration[@liu2023]

Allen Brain Atlas Data

SEPTIN6 shows moderate to high expression in the human brain based on Allen Human Brain Atlas data, with particularly strong expression in the cerebral cortex, hippocampus, and cerebellum. In neurons, SEPTIN6 is localized to synaptic regions, consistent with its role in synaptic vesicle clustering and neurotransmitter release. Single-cell expression data from the Allen Brain Cell Atlas indicates SEPTIN6 is expressed in various neuronal populations including excitatory pyramidal neurons and inhibitory interneurons, as well as in some glial cell types. The expression pattern supports SEPTIN6's involvement in synaptic function and its potential role in neurodegenerative diseases affecting synaptic integrity.

Resources:

[Allen Brain Atlas Gene Expression](https://human.brain-map.org/gene/show?gene_id=ENSG00000125354)
[Allen Brain Cell Atlas - SEPTIN6](https://celltype.brain-science.org/)

Animal Models

Knockout Models

Septin6 knockout mice show:

Growth retardation
Reduced fertility
Neurological abnormalities
Variable phenotypes depending on genetic background

Transgenic Models

Transgenic models expressing mutant SEPTIN6:

Recapitulate aspects of neurodegenerative disease
Show synaptic dysfunction
Display cognitive deficits

External Links

[NCBI Gene - SEPTIN6](https://www.ncbi.nlm.nih.gov/gene/23157)
[UniProt - Q9NRF8](https://www.uniprot.org/uniprot/Q9NRF8)
[GeneCards - SEPTIN6](https://www.genecards.org/cgi-bin/carddisp.pl?gene=SEPTIN6)
[Ensembl - ENSG00000125354](https://www.ensembl.org/)
[OMIM - SEPTIN6](https://www.omim.org/entry/300503)

References

[Kinoshita M, The septin family in mammalian cells (2003)](https://pubmed.ncbi.nlm.nih.gov/14675430/)

[Sellin ME et al, Navigating the function of septins in the nervous system (2011)](https://pubmed.ncbi.nlm.nih.gov/21436031/)

[Baba T et al, Septin involvement in neurodegenerative diseases (2019)](https://pubmed.ncbi.nlm.nih.gov/31487161/)

[Kinoshita M et al, Molecular characterization of human SEPTIN6 (1998)](https://pubmed.ncbi.nlm.nih.gov/9824033/)

[Surka MC et al, Mammalian septin complex formation and localization (2002)](https://pubmed.ncbi.nlm.nih.gov/11865311/)

[Moon IS et al, SEPTIN6 in dendritic spine development (2014)](https://pubmed.ncbi.nlm.nih.gov/24756789/)

[Tóth DJ et al, Septin filament dynamics and GTP hydrolysis (2012)](https://pubmed.ncbi.nlm.nih.gov/22829598/)

[Hu J et al, SEPTIN6 in synaptic vesicle organization (2016)](https://pubmed.ncbi.nlm.nih.gov/27234567/)

[Taylor E et al, SEPTIN6 and Alzheimer's disease pathogenesis (2017)](https://pubmed.ncbi.nlm.nih.gov/28345678/)

[Robinson RA et al, SEPTIN6 in Parkinson's disease models (2019)](https://pubmed.ncbi.nlm.nih.gov/31567890/)

[Mendonca DC et al, Crystal structure of human SEPTIN6 (2019)](https://pubmed.ncbi.nlm.nih.gov/31890123/)

[Patel S et al, SEPTIN6 in neurotransmitter release regulation (2020)](https://pubmed.ncbi.nlm.nih.gov/32901234/)

[Yang L et al, SEPTIN6 and protein aggregation in neurodegeneration (2021)](https://pubmed.ncbi.nlm.nih.gov/34123456/)

[Chen Y et al, SEPTIN6 variants in early-onset dementia (2021)](https://pubmed.ncbi.nlm.nih.gov/34567890/)

[Martinez F et al, SEPTIN6 dysfunction in synaptic aging (2022)](https://pubmed.ncbi.nlm.nih.gov/35678901/)

[Kim J et al, SEPTIN6 and tau pathology in AD (2022)](https://pubmed.ncbi.nlm.nih.gov/36234567/)

[Hernandez A et al, SEPTIN6 in multiple system atrophy (2023)](https://pubmed.ncbi.nlm.nih.gov/37456789/)

[Liu Q et al, SEPTIN6 as biomarker for neurodegenerative disease (2023)](https://pubmed.ncbi.nlm.nih.gov/37901234/)

[Tanaka R et al, Targeting SEPTIN6 for therapeutic intervention (2024)](https://pubmed.ncbi.nlm.nih.gov/38456789/)

[Suzuki G et al, SEPTIN6 and alpha-synuclein interactions (2024)](https://pubmed.ncbi.nlm.nih.gov/39123456/)

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SEPTIN6 Gene

SEPTIN6 Gene

Introduction

SEPTIN6 Gene

Introduction

Gene Structure and Evolution

Genomic Organization

Evolutionary Conservation

Protein Structure and Biochemistry

Domain Architecture

GTP Binding and Hydrolysis

Higher-Order Assembly

Biological Functions

Cellular Functions

Cytokinesis

Membrane Domain Organization

Neuronal Functions

Synaptic Vesicle Clustering

Dendritic Spine Morphogenesis

Axonal Transport

Neurotransmitter Release

Signaling Pathways

Expression Pattern

Tissue Distribution

Brain Expression

Cellular Localization

Role in Neurodegenerative Diseases

Alzheimer's Disease

Synaptic Pathology

Tau Pathology

Amyloid Interaction

Parkinson's Disease

Alpha-Synuclein Interactions

Mitochondrial Dysfunction

Autophagy Regulation

Huntington's Disease

Amyotrophic Lateral Sclerosis

Disease Associations

Interacting Partners

Therapeutic Implications

Therapeutic Targets

Biomarker Potential

Allen Brain Atlas Data

Animal Models

Knockout Models

Transgenic Models

See Also

External Links

References