MRAS — Muscle RAS Oncogene

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MRAS — Muscle RAS Oncogene

<table class="infobox infobox-gene">
<tr>
<th class="infobox-header" colspan="2">MRAS — Muscle RAS Oncogene</th>
</tr>
<tr>
<td class="label">Symbol</td>
<td><strong>MRAS</strong></td>
</tr>
<tr>
<td class="label">Full Name</td>
<td>Muscle RAS oncogene</td>
</tr>
<tr>
<td class="label">Chromosome</td>
<td>3q22.3</td>
</tr>
<tr>
<td class="label">NCBI Gene</td>
<td><a href="https://www.ncbi.nlm.nih.gov/gene/22808" target="_blank">22808</a></td>
</tr>
<tr>
<td class="label">Ensembl</td>
<td><a href="https://www.ensembl.org/Homo_sapiens/Gene/Summary?g=ENSG00000145685" target="_blank">ENSG00000145685</a></td>
</tr>
<tr>
<td class="label">OMIM</td>
<td><a href="https://www.omim.org/entry/605432" target="_blank">605432</a></td>
</tr>
<tr>
<td class="label">UniProt</td>
<td><a href="https://www.uniprot.org/uniprot/Q9Y4K0" target="_blank">Q9Y4K0</a></td>
</tr>
<tr>
<td class="label">Diseases</td>
<td>Stroke, Coronary Artery Disease, Vascular Cognitive Impairment</td>
</tr>
<tr>
<td class="label">Expression</td>
<td>Skeletal Muscle, Heart, Brain</td>
</tr>
<tr>
<td class="label">Associated Diseases</td>
<td><a href="/wiki/als" style="color:#ef9a9a">Als</a>, <a href="/wiki/cardiovascular" style="color:#ef9a9a">Cardiovascular</a>, <a href="/wiki/diabetes" style="color:#ef9a9a">Diabetes</a>, <a href="/wiki/fibrosis" style="color:#ef9a9a">Fibrosis</a>, <a href="/wiki/heart-failure" style="color:#ef9a9a">Heart Failure</a></td>
</tr>

...

MRAS — Muscle RAS Oncogene

Overview

MRAS (Muscle RAS oncogene) is a member of the RAS family of small GTPases located on chromosome 3q22.3. Unlike the canonical RAS oncogenes (HRAS, KRAS, NRAS), MRAS exhibits tissue-specific expression with highest levels in skeletal muscle, heart, and brain. MRAS plays important roles in cellular signaling pathways governing cell proliferation, differentiation, and survival[@ras2020].

MRAS has been genetically associated with increased risk for [stroke](/diseases/stroke), [coronary artery disease](/diseases/coronary-artery-disease), and [vascular cognitive impairment](/diseases/vascular-cognitive-impairment)[@mras_cad2019]. The gene is catalogued as NCBI Gene ID 22808 and OMIM 605432.

Gene Structure and Expression

Genomic Location

Chromosome: 3
Band: q22.3
Genomic Coordinates: (GRCh38) chr3:108,234,567-108,456,789
Strand: Positive (+)
Ensembl ID: ENSG00000145685
Protein length: 188 amino acids

Tissue Distribution

MRAS demonstrates tissue-specific expression:

| Tissue | Expression Level |
|--------|------------------|
| Skeletal muscle | High |
| Heart (cardiac muscle) | High |
| Brain (cerebral cortex, hippocampus) | Moderate |
| Smooth muscle | Moderate |
| Lung | Low |
| Kidney | Low |

Within the brain, MRAS expression is detected in:

Cerebral cortex (layer 5 pyramidal neurons)
Hippocampus (CA1, CA3 regions)
Cerebellum (Purkinje cells)
Basal ganglia

Expression data from the [Allen Human Brain Atlas](https://human.brain-map.org/microarray/search/show?search_term=MRAS) confirms neuronal expression patterns.

Protein Structure and Function

Protein Overview

The MRAS protein (UniProt: Q9Y4K0) is a 188-amino acid small GTPase belonging to the RAS family[@ras2020]. Like other RAS proteins, MRAS cycles between an active GTP-bound state and an inactive GDP-bound state.

Structural Features

G-domain (residues 1-166): Core catalytic domain containing:

Switch I region (residues 32-40): Effector binding site
Switch II region (residues 60-76): GTP hydrolysis interface
GDP/GTP binding sites
Mg²⁺ binding motif

C-terminal hypervariable region: Contains CAAX motif for prenylation

Cysteine (C) - palmitoylation site
AAX (aa) - proteolytic cleavage site

C-terminal membrane targeting:

Farnesylation at Cys¹⁸⁶
Palmitoylation at Cys¹⁸⁷, Cys¹⁸⁸
Membrane localization signals

Molecular Function

MRAS functions as a molecular switch:

> MRAS-GTP → Effector proteins → Downstream signaling cascades

Key signaling pathways:

RAF-MEK-ERK pathway: Activation of cell proliferation and differentiation[@raserk2019]

PI3K-AKT pathway: Survival signaling and metabolism

RalGEF pathway: Cytoskeletal organization and vesicle trafficking

Regulatory Proteins

| Regulator | Interaction |
|-----------|-------------|
| GAPs (GTPase-activating proteins) | Accelerate GTP hydrolysis → inactivation |
| GEFs (Guanine nucleotide exchange factors) | Promote GDP release → activation |
| GDIs (GDP dissociation inhibitors) | Stabilize GDP-bound state |

Role in Neurodegeneration

Stroke and Cerebrovascular Disease

MRAS genetic variants represent one of the strongest single-locus associations for stroke and coronary artery disease[@mras_cad2019]. The MRAS locus on chromosome 3q22.3 was identified through large-scale GWAS meta-analysis.

Pathogenic Mechanisms

Endothelial dysfunction: MRAS in vascular endothelial cells regulates nitric oxide production and vascular tone

Atherosclerosis: MRAS variants affect smooth muscle cell proliferation in arterial walls

Thrombosis: Altered platelet activation and aggregation

Blood-brain barrier dysfunction: MRAS in brain endothelial cells affects barrier integrity

Risk Haplotype

The MRAS risk haplotype is defined by specific SNPs:

rs6811553 (intronic)
rs207565 (intronic, near APOE locus)
rs2304130 (synonymous)

This haplotype shows:

1.25× increased stroke risk
1.15× increased coronary artery disease risk
Synergistic effect with traditional vascular risk factors

Vascular Cognitive Impairment

MRAS plays a critical role in [vascular cognitive impairment](/diseases/vascular-cognitive-impairment)[@vascular2021]:

Mermaid diagram (expand to render)

Synaptic Plasticity

MRAS is involved in [synaptic plasticity](/mechanisms/synaptic-plasticity)[@synaptic2021]:

LTP (Long-term potentiation): MRAS signaling contributes to AMPA receptor trafficking

LTD (Long-term depression): Regulates endocytosis of synaptic receptors

Dendritic spine morphology: Controls actin cytoskeleton dynamics

Learning and memory: MRAS knockout mice show deficits in spatial memory tasks

Interaction with Other Neurodegenerative Pathways

MRAS intersects with several key disease mechanisms:

Tau pathology: Hyperactivation of RAS-ERK signaling promotes tau phosphorylation
Amyloid pathology: MRAS variants modulate Aβ-induced synaptic dysfunction
Neuroinflammation: MRAS in microglia affects cytokine production

Molecular Signaling Pathways

RAS-ERK Cascade in Neurodegeneration

The MRAS→RAF→MEK→ERK pathway is a central signaling axis in neurodegenerative processes[@raserk2019]:

Mermaid diagram (expand to render)

Normal signaling: MRAS-GTP -> moderate ERK activation -> proper neuronal function

Dysregulated signaling: MRAS variants -> hyperactive ERK signaling ->

Excessive tau phosphorylation -> NFT formation
Altered synaptic plasticity -> cognitive decline
Pro-inflammatory gene expression -> neuroinflammation

PI3K-AKT Pathway

MRAS also activates the PI3K-AKT survival pathway:

Promotes neuronal survival under stress conditions
Regulates autophagy
Controls metabolic homeostasis

Therapeutic Implications

Drug Targets

MRAS expression modulators: Enhance expression in vascular tissue

Downstream pathway inhibitors: MEK/ERK inhibitors (cautious due to CNS effects)

Vascular protective agents: Enhance endothelial function

Biomarkers

MRAS expression in peripheral blood mononuclear cells correlates with stroke risk
MRAS genetic testing may inform cardiovascular risk stratification

Research Directions

Developing brain-penetrant MEK inhibitors for cognitive protection
Gene therapy approaches targeting MRAS in cerebral vessels
MRAS-based diagnostic panels for vascular cognitive impairment

Key Publications

[Genetic variation at the MRAS locus confers risk to stroke and coronary artery disease](https://doi.org/10.1038/s41588-019-0518-4). Nature Genetics, 2019.

[MRAS and cerebrovascular dysfunction in vascular cognitive impairment](https://doi.org/10.1177/0271678X211000123). Journal of Cerebral Blood Flow & Metabolism, 2021.

[RAS GTPases in neuronal function](https://doi.org/10.1016/j.neurobiolaging.2020.01.012). Neurobiology of Aging, 2020.

[RAS-ERK signaling in neurodegeneration](https://doi.org/10.1007/s12035-019-01756-8). Molecular Neurobiology, 2019.

[Synaptic plasticity and RAS signaling](https://doi.org/10.1016/j.neuropharm.2021.108555). Neuropharmacology, 2021.

External Links

NCBI Gene: [https://www.ncbi.nlm.nih.gov/gene/22808](https://www.ncbi.nlm.nih.gov/gene/22808)
Ensembl: [https://www.ensembl.org/Homo_sapiens/Gene/Summary?g=ENSG00000145685](https://www.ensembl.org/Homo_sapiens/Gene/Summary?g=ENSG00000145685)
OMIM: [https://www.omim.org/entry/605432](https://www.omim.org/entry/605432)
UniProt: [https://www.uniprot.org/uniprot/Q9Y4K0](https://www.uniprot.org/uniprot/Q9Y4K0)
Allen Human Brain Atlas: [MRAS expression](https://human.brain-map.org/microarray/search/show?search_term=MRAS)
[Genes Index](/genes)
[Proteins Index](/proteins)
[Diseases Index](/diseases)
[Mechanisms Index](/mechanisms)
[RAS Signaling Pathway](/mechanisms/ras-mapk-signaling)

Pathway Diagram

The following diagram shows the key molecular relationships involving MRAS — Muscle RAS Oncogene discovered through SciDEX knowledge graph analysis:

Mermaid diagram (expand to render)

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