HEY1 — Hairy/Enhancer-of-Split Related with YRPW Motif 1

HEY1 — Hairy/Enhancer-of-Split Related with YRPW Motif 1

<div class="infobox infobox-gene">
<table>
<tr><th colspan="2" style="background:#f0f0f0; text-align:center;">HEY1 Gene</th></tr> [@fischer2004]
<tr><td><strong>Gene Symbol</strong></td><td>HEY1</td></tr>
<tr><td><strong>Full Name</strong></td><td>Hairy/Enhancer-of-Split Related with YRPW Motif 1</td></tr>
<tr><td><strong>Chromosome</strong></td><td>8q21.13</td></tr>
<tr><td><strong>NCBI Gene ID</strong></td><td>[23493](https://www.ncbi.nlm.nih.gov/gene/23493)</td></tr> [@kato1997]
<tr><td><strong>OMIM</strong></td><td>605253</td></tr>
<tr><td><strong>Ensembl ID</strong></td><td>ENSG00000164690</td></tr>
<tr><td><strong>UniProt ID</strong></td><td>[Q9UQV3](https://www.uniprot.org/uniprot/Q9UQV3)</td></tr> [@leong2007]
<tr><td><strong>Associated Diseases</strong></td><td>[Alzheimer's Disease](/diseases/alzheimers-disease); [Parkinson's Disease](/diseases/parkinsons-disease); Cardiovascular Malformations; Neurodevelopmental Disorders</td></tr> [@anderson2011]
</table>
</div>

Overview

HEY1 — Hairy/Enhancer-of-Split Related with YRPW Motif 1

<div class="infobox infobox-gene">
<table>
<tr><th colspan="2" style="background:#f0f0f0; text-align:center;">HEY1 Gene</th></tr> [@fischer2004]
<tr><td><strong>Gene Symbol</strong></td><td>HEY1</td></tr>
<tr><td><strong>Full Name</strong></td><td>Hairy/Enhancer-of-Split Related with YRPW Motif 1</td></tr>
<tr><td><strong>Chromosome</strong></td><td>8q21.13</td></tr>
<tr><td><strong>NCBI Gene ID</strong></td><td>[23493](https://www.ncbi.nlm.nih.gov/gene/23493)</td></tr> [@kato1997]
<tr><td><strong>OMIM</strong></td><td>605253</td></tr>
<tr><td><strong>Ensembl ID</strong></td><td>ENSG00000164690</td></tr>
<tr><td><strong>UniProt ID</strong></td><td>[Q9UQV3](https://www.uniprot.org/uniprot/Q9UQV3)</td></tr> [@leong2007]
<tr><td><strong>Associated Diseases</strong></td><td>[Alzheimer's Disease](/diseases/alzheimers-disease); [Parkinson's Disease](/diseases/parkinsons-disease); Cardiovascular Malformations; Neurodevelopmental Disorders</td></tr> [@anderson2011]
</table>
</div>

Overview

HEY1 (Hairy/Enhancer-of-Split Related with YRPW Motif 1) is a basic helix-loop-helix-Orange (bHLH-O) transcriptional regulator that functions as a key effector of [Notch signaling](/mechanisms/notch-signaling-pathway). HEY1 is induced by Notch receptor activation and regulates downstream target genes involved in cell fate determination, differentiation, tissue morphogenesis, and cellular homeostasis. As a member of the Hairy and Enhancer of Split (HES/HEY) family, HEY1 plays critical roles in nervous system development and has been implicated in [Alzheimer's Disease](/diseases/alzheimers-disease), [Parkinson's Disease](/diseases/parkinsons-disease), and various neurodevelopmental and cardiovascular disorders. [@bray2016]

Unlike classical HES proteins that function primarily as transcriptional repressors, HEY1 possesses both repressor and activator functions depending on cellular context. The HEY family proteins (HEY1, HEY2, HEYL) represent evolutionary conserved effectors of Notch signaling that integrate Notch pathway activity with other developmental signaling pathways including Wnt, Hedgehog, and BMP. [@chiba2018]

Gene and Protein Structure

The HEY1 gene (ENSG00000164690) is located on chromosome 8q21.13 and encodes a protein of approximately 299 amino acids with a molecular weight of ~33 kDa. Like other bHLH-O family members, HEY1 contains several conserved functional domains:

| Domain | Position | Function |
|--------|----------|----------|
| bHLH domain | aa 43-95 | DNA binding; dimerization with other bHLH proteins |
| Orange domain | aa 107-149 | Protein-protein interactions; transcriptional regulation |
| TEA domain | aa 1-30 | Transcriptional activation (in some contexts) |
| YRPW motif | aa 191-237 | Co-repressor recruitment; protein interactions |
| C-terminal tetrapeptide | aa 270-273 | Groucho/TLE co-repressor binding |

The bHLH domain enables HEY1 to bind the canonical E-box motif (CANNTG) as either homodimers or heterodimers with other bHLH proteins such as HES1, HES5, or Tisch (TNC). The Orange domain mediates specific protein-protein interactions that distinguish HEY1 from HES family members. The YRPW motif (also found in HEY2 and HEYL) allows HEY1 to recruit transcriptional co-repressors including Groucho/TLE family proteins, histone deacetylases (HDACs), and other chromatin modifiers. [@kovall2018]

Function in Notch Signaling Pathway

Canonical Notch Pathway

HEY1 is a direct transcriptional target of Notch receptor signaling. The canonical pathway proceeds as follows:

HEY1 then regulates downstream target genes involved in cell fate decisions, maintaining progenitor cell pools, and directing differentiation programs. [@nakagawa2004]

HEY1 as Notch Effector

Unlike HES proteins that maintain progenitor identity through lateral inhibition, HEY1 often functions in different contexts:

• Mesenchymal differentiation: HEY1 promotes osteogenesis, chondrogenesis, and smooth muscle differentiation
• Neurogenesis: HEY1 regulates neuronal differentiation, astrogliogenesis, and neural stem cell maintenance
• Angiogenesis: HEY1 controls vascular development and endothelial cell specification
• Circadian rhythm: HEY1 contributes to Notch-mediated circadian gene regulation

Cross-talk with Other Pathways

HEY1 integrates Notch signaling with multiple developmental pathways:

• Wnt/β-catenin: HEY1 can antagonize or cooperate with Wnt signaling depending on context
• BMP/SMAD: HEY1 interacts with SMAD proteins to modulate BMP-responsive genes
• Hedgehog: Notch and Hedgehog pathways converge on HEY1 regulation in some contexts
• Hippo/YAP: Mechanical signaling influences HEY1 expression through YAP/TAZ

Role in Nervous System Development

Neuronal Differentiation

HEY1 plays critical roles in neuronal development:

• Neural progenitor maintenance: HEY1 helps maintain neural progenitor cell pools during development
• Neuronal specification: HEY1 expression distinguishes different neuronal subtypes
• Astrocyte differentiation: HEY1 influences the transition from neural progenitors to astrocytes
• Synaptic development: HEY1 regulates genes involved in synapse formation and function

Neural Stem Cell Regulation

In adult neurogenic niches (subventricular zone, dentate gyrus), HEY1 continues to regulate neural stem cell behavior:

• Stem cell maintenance: HEY1 contributes to maintaining neural stem cell identity
• lineage decisions: HEY1 influences whether stem cells differentiate into neurons or glia
• Aging: HEY1 expression declines with age, correlating with reduced neurogenesis
• Disease: HEY1 dysregulation is observed in neurodegenerative disease contexts

Expression Pattern

Brain Expression

HEY1 shows distinct expression patterns in the developing and adult brain:

| Brain Region | Expression Level | Cell Types |
|-------------|-----------------|------------|
| Cerebral Cortex | Moderate | Neural progenitors, some neurons |
| Hippocampus | Moderate | Dentate gyrus progenitors, CA1 neurons |
| Subventricular Zone | High | Neural stem cells |
| Cerebellum | Moderate | Granule cell progenitors |
| Basal Ganglia | Low-Moderate | Striatal neurons |

Cellular Distribution

• Neural progenitor cells: High expression in ventricular and subventricular zones
• Immature neurons: Moderate expression during neuronal differentiation
• Astrocytes: Low expression in mature astrocytes
• Oligodendrocyte precursors: Present in developing white matter

Disease Associations

Alzheimer's Disease

HEY1 dysfunction contributes to [Alzheimer's Disease](/diseases/alzheimers-disease) through multiple mechanisms:

• Amyloid-beta impact: Aβ accumulation alters Notch signaling and HEY1 expression
• Neural progenitor dysfunction: HEY1 dysregulation impairs adult neurogenesis in the hippocampus
• Synaptic pathology: HEY1 regulates synaptic proteins that are downregulated in AD
• Neuroinflammation: Notch-HEY1 signaling modulates microglial activation states

Parkinson's Disease

In [Parkinson's Disease](/diseases/parkinsons-disease), HEY1 plays complex roles:

• Dopaminergic neuron development: HEY1 is involved in substantia nigra development
• α-synuclein pathology: HEY1 expression is altered in PD models with Lewy bodies
• Neuroinflammation: Notch-HEY1 signaling modulates microglial responses
• Therapeutic potential: Modulating HEY1 may protect dopaminergic neurons

Cardiovascular Malformations

HEY1 was originally identified as critical for cardiovascular development:

• Valve formation: HEY1 regulates endocardial cushion formation
• Vascular development: HEY1 controls arterial specification and remodeling
• Cardiogenesis: HEY1 is required for proper heart chamber development

Neurodevelopmental Disorders

Altered HEY1 expression or function is associated with:

• Intellectual disability: HEY1 variants found in some cases
• Autism spectrum disorder: HEY1 dysregulation observed in ASD models
• Schizophrenia: HEY1 expression altered in postmortem brain studies

Therapeutic Implications

Drug Development

The Notch-HEY1 axis represents a therapeutic target:

• Notch inhibitors: γ-secretase inhibitors modulate HEY1 expression
• Notch agonists: Jagged ligands can enhance Notch-HEY1 signaling
• bHLH modulators: Small molecules targeting HEY1 dimerization are under development

Biomarker Potential

HEY1 expression may serve as a biomarker for:

• Notch pathway activity in disease states
• Neural stem cell activation
• Treatment response to Notch-modulating therapies

Key Publications

Cross-links

• [Notch Signaling Pathway](/mechanisms/notch-signaling-pathway)
• [Notch Signaling in Neurodegeneration](/mechanisms/notch-signaling-neurodegeneration)
• [Notch Signaling in Parkinson's Disease](/mechanisms/notch-signaling-parkinsons)
• [Alzheimer's Disease](/diseases/alzheimers-disease)
• [Parkinson's Disease](/diseases/parkinsons-disease)
• [Neurogenesis](/mechanisms/adult-neurogenesis-neurodegeneration)
• [Neural Stem Cells](/mechanisms/neural-stem-cells)

See Also

• [HEY2 Gene](/genes/hey2) - HEY1 paralog
• [HEYL Gene](/genes/heyl) - HEY family member
• [HES1 Gene](/genes/hes1) - HES family member
• [Notch Signaling](/mechanisms/notch-signaling-pathway) - Overview of Notch pathways
• [Notch-Notch Signaling](/mechanisms/notch-signaling-neurodegeneration) - Notch in neurodegeneration

External Links

• [NCBI Gene: HEY1](https://www.ncbi.nlm.nih.gov/gene/23493)
• [UniProt: Q9UQV3](https://www.uniprot.org/uniprot/Q9UQV3)
• [Ensembl: ENSG00000164690](https://www.ensembl.org/Homo_sapiens/Gene/Summary?g=ENSG00000164690)
• [Allen Brain Atlas: HEY1 Expression](https://human.brain-map.org/microarray/search/show?search_term=HEY1)
• [GTEx Portal: HEY1](https://gtexportal.org/home/gene/HEY1)

References