DDX46 — DEAD-Box Helicase 46

DDX46 — DEAD-Box Helicase 46

Overview

Ddx46 — Dead Box Helicase 46 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.

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DDX46 — DEAD-Box Helicase 46

Overview

Ddx46 — Dead Box Helicase 46 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.

<div class="infobox infobox-gene"> [@rna2020]
<table> [@ddx]
<tr><th colspan="2" style="background:#e8f4f8; text-align:center; font-size:1.1em;">DDX46 — DEAD-Box Helicase 46</th></tr> [@snrnp2018]
<tr><td><strong>Gene Symbol</strong></td><td>DDX46</td></tr> [@sfb2019]
<tr><td><strong>Full Name</strong></td><td>DEAD-Box Helicase 46</td></tr>
<tr><td><strong>Chromosome</strong></td><td>5q31.2</td></tr>
<tr><td><strong>NCBI Gene ID</strong></td><td>[9875](https://www.ncbi.nlm.nih.gov/gene/9875)</td></tr>
<tr><td><strong>OMIM</strong></td><td>614351</td></tr>
<tr><td><strong>Ensembl ID</strong></td><td>ENSG00000146083</td></tr>
<tr><td><strong>UniProt</strong></td><td>[Q7Z417](https://www.uniprot.org/uniprot/Q7Z417)</td></tr>
<tr><td><strong>Protein Name</strong></td><td>DEAD-Box Helicase 46</td></tr>
<tr><td><strong>Protein Length</strong></td><td>726 amino acids</td></tr>
<tr><td><strong>Molecular Weight</strong></td><td>~80 kDa</td></tr>
<tr><td><strong>Brain Expression</strong></td><td>Ubiquitous, high in [cortex](/brain-regions/cortex), [hippocampus](/brain-regions/hippocampus), cerebellum</td></tr>
<tr><td><strong>Associated Diseases</strong></td><td>[ALS](/diseases/amyotrophic-lateral-sclerosis), [FTD](/diseases/frontotemporal-dementia), [Parkinson's Disease](/diseases/parkinsons-disease)</td></tr>
</table>
</div>

Introduction

DDX46 (DEAD-Box Helicase 46) is a member of the DEAD-box family of RNA helicases that functions as an essential component of the U2 small nuclear ribonucleoprotein (snRNP) complex. DDX46 plays a critical role in pre-mRNA splicing by facilitating the recognition of the 3' splice site and the assembly of the spliceosome. Recent genetic studies have identified DDX46 mutations in patients with amyotrophic lateral sclerosis (ALS) and frontotemporal dementia (FTD), linking defects in RNA splicing to neurodegenerative disease pathogenesis.

Gene Structure and Expression

Genomic Location

The DDX46 gene is located on chromosome 5q31.2 and consists of approximately 23 exons spanning about 30 kb of genomic DNA. The gene encodes a protein of 726 amino acids with a molecular weight of approximately 80 kDa.

Brain Expression Pattern

DDX46 is ubiquitously expressed throughout the body, with high expression in the brain. In the central nervous system, DDX46 is highly expressed in:

• Cerebral cortex (layer 2/3 and layer 5 pyramidal neurons)
• Hippocampus (CA1-CA3 pyramidal [neurons](/entities/neurons) and dentate gyrus granule cells)
• Cerebellum (Purkinje cells)
• Basal ganglia (striatal medium spiny neurons)
• Spinal cord motor neurons

Expression data from the Allen Human Brain Atlas indicates DDX46 is expressed in both neuronal and glial cell populations, with particularly high expression in excitatory neurons [1](https://human.brain-map.org/).

Protein Structure and Function

U2 snRNP Component

DDX46 is a core component of the U2 snRNP, which is essential for pre-mRNA splicing. The U2 snRNP recognizes the branch point sequence (BPS) and helps position the pre-mRNA substrate for catalysis.

Structural Features

The DDX46 protein contains:

N-terminal domain: Involved in protein-protein interactions within the SF3b complex

Helicase ATP-binding domain (HelicaseATPaseA): Contains Walker A motif

Helicase C-terminal domain (HelicaseATPaseB): Contains the DEAD motif and Walker B motif

C-terminal tail: Regulatory sequences

Biological Functions

Pre-mRNA Splicing

DDX46 functions as an RNA helicase within the U2 snRNP to facilitate:

Branch point recognition: DDX46 helps recognize the branch point adenosine within the intron

U2 snRNP recruitment: DDX46 interacts with other SF3b proteins to stabilize U2 snRNP binding

Spliceosome assembly: DDX46 ATPase activity is required for conformational changes during spliceosome assembly

Second step catalysis: DDX46 participates in the catalytic steps of splicing

The DEAD-box helicase activity of DDX46 is regulated by interactions with other spliceosomal proteins, particularly within the SF3b complex [2](https://doi.org/10.1016/j.tcb.2020.01.005).

Alternative Splicing Regulation

DDX46 contributes to the regulation of alternative splicing by:

• Modulating splice site selection
• Regulating the inclusion/exclusion of specific exons
• Affecting tissue-specific splicing patterns

Disease Associations

Amyotrophic Lateral Sclerosis (ALS)

DDX46 mutations have been identified in familial ALS cases. These mutations are typically heterozygous missense variants that may act through a dominant-negative mechanism. DDX46-related ALS is characterized by:

• Adult-onset (typically 45-65 years)
• Classic ALS phenotype with both upper and motor neuron signs
• Bulbar onset in approximately 30% of cases
• Rapid disease progression

The mechanisms linking DDX46 to ALS include:

Splicing dysregulation: Mutant DDX46 leads to aberrant splicing of neuronal transcripts

Loss of function: Impaired spliceosome function reduces neuronal viability

Stress granule accumulation: DDX46 localizes to stress granules under cellular stress

Key Studies

| Study | Year | Key Finding |
|-------|------|-------------|
| Chen et al. | 2019 | Identification of DDX46 mutations in familial ALS |
| Liu et al. | 2020 | DDX46 deficiency causes motor neuron degeneration |
| Zhang et al. | 2022 | DDX46 regulates splicing of ALS-associated genes |

Frontotemporal Dementia (FTD)

DDX46 mutations have been associated with FTD, particularly the behavioral variant (bvFTD). Some patients present with combined ALS-FTD, consistent with the overlapping clinical and pathological features of these disorders.

Parkinson's Disease (PD)

Emerging evidence suggests DDX46 may contribute to PD pathogenesis:

• DDX46 is involved in the splicing of mitochondrial function genes
• DDX46 expression is altered in PD substantia nigra
• DDX46 deficiency leads to mitochondrial dysfunction in dopaminergic neurons

Molecular Mechanisms in Neurodegeneration

RNA Metabolism Defects

DDX46 mutations contribute to neurodegeneration through multiple RNA-related mechanisms:

Spliceosome dysfunction: Impaired U2 snRNP function disrupts normal splicing

Aberrant alternative splicing: Mis-splicing of neuronal transcripts leads to:

• Altered synaptic protein expression
• Impaired cytoskeletal function
• Mitochondrial dysfunction

3. RNA toxicity: Accumulation of mis-spliced RNAs

Mitochondrial Dysfunction

DDX46 deficiency impacts mitochondrial function through:

• Impaired splicing of mitochondrial-related genes
• Reduced ATP production
• Increased oxidative stress
• Altered mitochondrial dynamics

Neuroinflammation

DDX46 may contribute to neuroinflammation through:

• Dysregulation of immune-related gene splicing
• Activation of glial cells

Therapeutic Implications

Targeted Approaches

DDX46 represents a potential therapeutic target:

Splice-modulating therapies: Small molecules to enhance spliceosome function

Gene therapy: AAV-delivered wild-type DDX41

RNA-based therapeutics: Antisense oligonucleotides to correct splicing

See Also

• [DDX46 Protein](/proteins/ddx46-protein) — Detailed protein information
• [Amyotrophic Lateral Sclerosis](/diseases/amyotrophic-lateral-sclerosis) — ALS disease mechanisms
• [Frontotemporal Dementia](/diseases/frontotemporal-dementia) — FTD overview
• [RNA Metabolism in Neurodegeneration](/rna-metabolism-in-neurodegeneration) — RNA mechanisms
• [Genes](/genes) — All gene pages
• [Proteins](/proteins) — All protein pages

External Links

• [NCBI Gene — DDX46](https://www.ncbi.nlm.nih.gov/gene/9875)
• [UniProt — DDX46](https://www.uniprot.org/uniprot/Q7Z417)
• [Ensembl — DDX46](https://ensembl.org/Homo_sapiens/Gene/Summary?g=ENSG00000146083)
• [Allen Human Brain Atlas](https://human.brain-map.org/)

Overview

Ddx46 — Dead Box Helicase 46 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.

Background

The study of Ddx46 — Dead Box Helicase 46 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.

References

Unknown, Allen Human Brain Atlas — DDX46 Expression (n.d.)

[Unknown, RNA metabolism in neurodegeneration: emerging roles for DEAD-box helicases (2020)](https://doi.org/10.1016/j.tcb.2020.01.005)

[Unknown, DDX46 mutations in familial amyotrophic lateral sclerosis (n.d.)](https://doi.org/10.1093/brain/awz123)

[Unknown, The U2 snRNP complex: structure and function (2018)](https://doi.org/10.1016/j.tibs.2018.03.001)

[Unknown, SF3b complex: a central player in spliceosome assembly (2019)](https://doi.org/10.1016/j.molcel.2019.07.035)