IFI204 Gene

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IFI204 Gene

Overview

<table class="infobox infobox-gene">
<tr>
<th class="infobox-header" colspan="2">IFI204 Gene</th>
</tr>
<tr>
<td class="label">Cell Type</td>
<td>Expression Level</td>
</tr>
<tr>
<td class="label">[Microglia](/cell-types/microglia-neuroinflammation)</td>
<td>High</td>
</tr>
<tr>
<td class="label">[Astrocytes](/entities/astrocytes)</td>
<td>Moderate</td>
</tr>
<tr>
<td class="label">[Neurons](/entities/neurons)</td>
<td>Low-Moderate</td>
</tr>
<tr>
<td class="label">Oligodendrocytes</td>
<td>Low</td>
</tr>
<tr>
<td class="label">Brain endothelial cells</td>
<td>Low</td>
</tr>
<tr>
<td class="label">KG Connections</td>
<td><a href="/atlas" style="color:#4fc3f7">1 edges</a></td>
</tr>
</table>

Ifi204 Gene plays an important role in the study of neurodegenerative diseases. This page provides comprehensive information about this topic, including its mechanisms, significance in disease processes, and therapeutic implications.

Introduction

...

IFI204 Gene

Overview

Introduction

IFI204 (Interferon Alpha Inducible Protein 204), also known as AIM2 (Absence in Melanoma 2) or PYHIN1, is a member of the AIM2-like receptor (ALR) family of proteins. This gene encodes a cytosolic DNA sensor that plays a critical role in innate immunity and inflammasome activation. While traditionally studied in the context of cancer and autoimmune diseases, emerging research reveals important functions in the central nervous system, particularly in neurodegenerative diseases including Alzheimer's disease (AD), Parkinson's disease (PD), amyotrophic lateral sclerosis (ALS), and frontotemporal dementia (FTD). [@choubey2010]

Gene Structure and Protein Architecture

The IFI204 gene spans approximately 21 kb on chromosome 1q23.1 and consists of 8 exons encoding a protein of 414 amino acids with a molecular weight of approximately 46 kDa. The protein structure comprises two key functional domains:

Pyrin Domain (PYD)

The N-terminal pyrin domain (~90 amino acids) mediates homotypic protein-protein interactions through PYHIN family-specific interactions. This domain allows IFI204 to recruit adapter proteins and initiate downstream signaling cascades.

HIN-200 Domain

The C-terminal HIN-200 domain (~200 amino acids) is responsible for DNA binding. This domain contains two OB-fold motifs that together form a single-stranded DNA binding surface. The HIN-200 domain can bind both double-stranded and single-stranded DNA with preference for longer DNA fragments (>80 bp).

Molecular Functions

DNA Sensing and Inflammasome Activation

IFI204 functions as a canonical cytosolic DNA sensor. Upon binding to foreign or host-derived DNA in the cytosol:

DNA binding: The HIN-200 domain binds DNA, causing a conformational change that exposes the PYD

Oligomerization: IFI204 assembles into a filamentous inflammasome platform

Adapter recruitment: The PYD recruits ASC (PYCARD) adapter protein through homotypic PYD-PYD interactions

Caspase-1 activation: ASC recruits pro-caspase-1, leading to its autoproteolytic activation

Inflammatory cytokine processing: Active caspase-1 cleaves pro-IL-1β and pro-IL-18 to their active forms

Type I Interferon Response

IFI204 can also induce type I interferon (IFN-α/β) production through activation of the STING-TBK1-IRF3 pathway, though this function is more prominent for related family member IFI16.

Interactome

Key protein interactions include:

ASC (PYCARD): Adapter for inflammasome assembly
Caspase-1 (CASP1): Effector protease
AIM2: Can form heterodimers
IFI16: Related family member
STING (TMEM173): Upstream activator

Expression in the Brain

Cellular Distribution

In the central nervous system, IFI204 shows a distinctive expression pattern:

Regulation of Expression

IFI204 expression is tightly regulated by:

Type I interferons (IFN-α, IFN-β): Strong upregulation
Type II interferon (IFN-γ): Moderate induction
TNF-α: Synergistic with interferons
Aging: Increased expression in aged brain
Pathological stimuli: Aβ, [α-synuclein](/proteins/alpha-synuclein), [TDP-43](/mechanisms/tdp-43-proteinopathy)

Role in Alzheimer's Disease

Inflammasome Activation

The AIM2 inflammasome is significantly activated in AD brain tissue:

AIM2/IFI204 protein levels are elevated in prefrontal [cortex](/brain-regions/cortex) and [hippocampus](/brain-regions/hippocampus) of AD patients
Colocalization with [amyloid-beta](/proteins/amyloid-beta) plaques suggests ongoing inflammasome activation
Active caspase-1 and ASC specks are abundant in AD microglia

Molecular Mechanisms

Aβ-induced activation: Amyloid-beta oligomers and fibrils can induce IFI204 inflammasome activation in microglia

DNA damage: Neuronal DNA damage in AD may provide endogenous ligands for IFI204

Microglial priming: IFI204 contributes to the primed state of microglia in AD

[Tau](/proteins/tau) pathology: Cross-talk between AIM2 and tau pathology has been reported

Therapeutic Implications

Small molecule inhibitors: AIM2 inflammasome inhibitors are in development
Targeting IL-1β: Anti-IL-1β therapies may benefit AD patients
DNA damage repair: Enhancing neuronal DNA repair may reduce IFI204 activation

Role in Parkinson's Disease

Substantia Nigra Involvement

Elevated IFI204/AIM2 expression has been observed in:

Substantia nigra pars compacta of PD patients
Microglia surrounding dopaminergic neurons
Lewy bodies (colocalization with α-synuclein)

Mechanisms

α-Synuclein-induced inflammation: α-synuclein aggregates can activate IFI204 inflammasome
Mitochondrial DNA: Damaged mitochondria release mtDNA that activates cytosolic DNA sensors
Microglial activation: Chronic inflammation drives dopaminergic neuron loss

Role in ALS and FTD

TDP-43 Pathology

IFI204 is activated in ALS and FTD with TDP-43 pathology:

TDP-43 aggregation may disrupt normal DNA handling in neurons
Neuronal DNA damage triggers IFI204 inflammasome
Motor neurons show particular vulnerability

C9orf72 Connection

The [C9orf72](/entities/c9orf72) repeat expansion, the most common genetic cause of ALS/FTD, may intersect with IFI204 pathways through:

Dysregulated [autophagy](/entities/autophagy) leading to DNA accumulation
Altered innate immune responses

Research Methods

Detection in Brain Tissue

Immunohistochemistry: Antibody detection in fixed brain sections
Western blot: Protein level quantification
qPCR: mRNA expression analysis
ELISA: Cytokine (IL-1β, IL-18) measurement

Functional Studies

In vitro inflammasome assays: ASC speck formation
Primary neuron/microglia cultures: Mechanism studies
CRISPR-Cas9: Genetic manipulation
Animal models: Transgenic and knock-in models

Biomarker Potential

CSF IFI204: Under investigation as a biomarker
Blood inflammatory markers: Correlates with disease progression

Therapeutic Targeting

Drug Development

Several approaches are being explored:

Direct AIM2 inhibitors: Small molecules blocking DNA binding

ASC inhibitors: Preventing inflammasome assembly

Caspase-1 inhibitors: Reducing downstream inflammation

IL-1 receptor antagonists: Blocking cytokine effects

Repurposing Opportunities

Existing drugs with potential:

Colchicine: Anti-inflammatory, microtubule effects
Anakinra: IL-1 receptor antagonist
Canakinumab: Anti-IL-1β antibody

Summary

IFI204/AIM2 represents a critical link between DNA sensing, innate immunity, and neurodegenerative disease pathogenesis. While primarily characterized in peripheral immune cells, emerging evidence demonstrates important functions in brain cells, particularly microglia. The inflammasome activation driven by IFI204 contributes to chronic neuroinflammation in AD, PD, ALS, and FTD. Targeting this pathway offers therapeutic potential, though challenges remain in achieving brain penetration and achieving selective modulation.

External Links

[PubMed](https://pubmed.ncbi.nlm.nih.gov/)

Overview

Background

The study of Ifi204 Gene has evolved significantly over the past decades. Research in this area has revealed important insights into the underlying mechanisms of neurodegeneration and continues to drive therapeutic development.

Historical context and key discoveries in this field have shaped our current understanding and will continue to guide future research directions.

[Allen Human Brain Atlas - IFO204](https://human.brain-map.org/microarray/search/show?search_term=IFO204)
[Allen Cell Type Atlas - ifo204](https://celltypes.brain-map.org/)
[Allen Mouse Brain Atlas - ifo204](https://mouse.brain-map.org/)

References

[Hornung V et al., AIM2 is essential for the host immune response to cytosolic DNA (2009) (2009)](https://pubmed.ncbi.nlm.nih.gov/19701257/)

[Choubey D et al., Interferon-inducible IFI16 protein in human cancers (2010) (2010)](https://pubmed.ncbi.nlm.nih.gov/20562891/)

[Dziembowska M et al., High expression of AIM2 in brain areas (2013) (2013)](https://pubmed.ncbi.nlm.nih.gov/23626765/)

[Couturier J et al., AIM2 inflammasome in Alzheimer's disease (2016) (2016)](https://pubmed.ncbi.nlm.nih.gov/27282374/)

[Wu PJ et al., AIM2 in Parkinson's disease (2020) (2020)](https://pubmed.ncbi.nlm.nih.gov/32044821/)

[Zhao N et al., Type I interferon response in neurodegeneration (2022) (2022)](https://pubmed.ncbi.nlm.nih.gov/35292367/)

[De Rivero Vaccari JP et al., Inflammasome formation in ALS (2022) (2022)](https://pubmed.ncbi.nlm.nih.gov/35898321/)

[Frederick NM et al., Targeting AIM2 for neurodegenerative disease treatment (2023) (2023)](https://pubmed.ncbi.nlm.nih.gov/37452189/)

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IFI204 Gene

IFI204 Gene

Overview

Introduction

IFI204 Gene

Overview

Introduction

Gene Structure and Protein Architecture

Pyrin Domain (PYD)

HIN-200 Domain

Molecular Functions

DNA Sensing and Inflammasome Activation

Type I Interferon Response

Interactome

Expression in the Brain

Cellular Distribution

Regulation of Expression

Role in Alzheimer's Disease

Inflammasome Activation

Molecular Mechanisms

Therapeutic Implications

Role in Parkinson's Disease

Substantia Nigra Involvement

Mechanisms

Role in ALS and FTD

TDP-43 Pathology

C9orf72 Connection

Research Methods

Detection in Brain Tissue

Functional Studies

Biomarker Potential

Therapeutic Targeting

Drug Development

Repurposing Opportunities

Summary

See Also

External Links

Overview

Background

References