HEY2 Gene

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<table class="infobox infobox-gene">
<tr>
<th class="infobox-header" colspan="2">HEY2 Gene</th>
</tr>
<tr>
<td class="label">Gene Symbol</td>
<td>HEY2</td>
</tr>
<tr>
<td class="label">Alternative Names</td>
<td>HRT2, HERP2, HESR2, GRR1</td>
</tr>
<tr>
<td class="label">Chromosomal Location</td>
<td>6q22.31</td>
</tr>
<tr>
<td class="label">Ensembl ID</td>
<td>ENSG00000180872</td>
</tr>
<tr>
<td class="label">NCBI Gene ID</td>
<td>9489</td>
</tr>
<tr>
<td class="label">OMIM</td>
<td>604674</td>
</tr>
<tr>
<td class="label">UniProt ID</td>
<td>Q9UBX5</td>
</tr>
<tr>
<td class="label">Protein Length</td>
<td>299 amino acids</td>
</tr>
<tr>
<td class="label">Molecular Weight</td>
<td>~33 kDa</td>
</tr>
<tr>
<td class="label">Developmental Stage</td>
<td>Expression Pattern</td>
</tr>
<tr>
<td class="label">Embryonic day 7-9</td>
<td>Neural tube, somites</td>
</tr>
<tr>
<td class="label">Embryonic day 10-14</td>
<td>Heart, vasculature</td>
</tr>
<tr>
<td class="label">Embryonic day 15-18</td>
<td>Forebrain, retina</td>
</tr>
<tr>
<td class="label">Tissue/Cell Type</td>
<td>Expression Level</td>
</tr>
<tr>
<td class="label">Heart</td>
<td>High</td>
</tr>
<tr>
<td class="label">Brain (cortex, hippocampus)</td>
<td>Moderate-High</td>
</tr>
<tr>
<td class="label">Lung</td>
<td>Modera

...

Overview

HEY2 (Hairy/Enhancer-of-Split Related with YRPW Motif 2), also known as Hairy and Transcription Factor 2, is a basic helix-loop-helix (bHLH) transcription factor that functions as a transcriptional repressor. It is encoded by the HEY2 gene located on chromosome 6q22.31 and is a key downstream target of Notch signaling. HEY2 plays essential roles in cardiovascular development, neurogenesis, and tissue patterning. The protein is part of the Hey family (HEY1, HEY2, HEYL), which are conserved transcriptional repressors that mediate Notch signaling effects. In the adult brain, HEY2 is expressed in regions involved in learning and memory, and altered HEY2 expression has been implicated in Alzheimer's disease and other neurodegenerative conditions. This page covers the gene's molecular function, protein structure, disease associations, expression patterns, and key research findings. [@ncbi][@uniprot]

Gene Information

Protein Structure and Domains

HEY2 contains several distinct structural domains that mediate its function as a transcriptional repressor:

Basic Helix-Loop-Helix (bHLH) Domain

The N-terminal bHLH domain (approximately 60-70 amino acids) consists of:

Basic region: DNA-binding motif that recognizes E-box sequences (CANNTG)
Helix-loop-helix: Dimerization domain allowing HEY2 to form homodimers or heterodimers with other bHLH proteins

YRPW Motif

The characteristic YRPW (Tyr-Arg-Pro-Trp) motif is present in all Hey family members:

Located in the C-terminal region
Mediates protein-protein interactions
Essential for transcriptional repressor function

Proline-Rich Region

The C-terminal region contains proline-rich sequences that may:

Serve as transcriptional activation or repression domains
Provide binding sites for SH3 domain-containing proteins
Contribute to protein-protein interactions

Orange Domain

Located between the bHLH and YRPW motifs:

Characteristic of the Hey family
May contribute to transcriptional repression specificity

Molecular Mechanism of Action

DNA Binding

HEY2 functions as a sequence-specific transcription factor:

Dimer Formation: HEY2 forms homodimers or heterodimers with other bHLH proteins (e.g., HEY1, HES1)

E-box Recognition: The dimer binds to E-box sequences (CANNTG) in target gene promoters

Transcriptional Repression: HEY2 recruits co-repressor complexes to silence gene expression

Transcriptional Repression

HEY2 represses transcription through multiple mechanisms:

Direct DNA binding: Binds to E-box sequences in target gene promoters
Co-repressor recruitment: Recruits histone deacetylases (HDACs) and other repressor complexes
Competition: Competes with transcriptional activators for DNA binding sites
Dominant-negative activity: Can interfere with other bHLH transcription factors

Notch Signaling Integration

HEY2 is a canonical Notch signaling target:

Notch activation: Notch receptors are activated by ligands (Delta, Jagged)

Cleavage: Notch undergoes proteolytic cleavage, releasing the intracellular domain (NICD)

Nuclear translocation: NICD translocates to the nucleus

Transcription activation: NICD forms a complex with CSL transcription factor

HEY2 expression: Notch-CSL complex activates HEY2 transcription

Feedback repression: HEY2 represses Notch target genes, creating negative feedback

Target Genes

HEY2 regulates various target genes involved in:

Cell cycle (p21, cyclin D1)
Apoptosis (Bim, Noxa)
Differentiation (MyoD, NeuroD)
Development (cardiac genes, neural genes)

Expression Pattern

HEY2 exhibits dynamic expression patterns during development and in adulthood:

During Development

In Adult Tissues

In Adult Brain

In the adult brain, HEY2 is expressed in:

Pyramidal neurons in the cortex
Hippocampal CA1 and CA3 regions
Cerebellar Purkinje cells
Subventricular zone (neural stem cells)

Disease Associations

Alzheimer's Disease

HEY2 has emerging relevance to AD through several mechanisms:

Notch Dysregulation: The Notch signaling pathway is altered in AD brains. HEY2, as a Notch target, may reflect or contribute to this dysregulation. Notch is involved in synaptic plasticity and memory formation.

Neuronal Survival: HEY2 can regulate pro-survival and pro-apoptotic genes. Altered HEY2 expression may affect neuronal survival in AD.

Amyloid-Beta Effects: Amyloid-beta can affect Notch signaling, potentially altering HEY2 expression. The relationship between amyloid pathology and HEY2 is being investigated.

Synaptic Function: Notch and HEY2 are involved in synaptic plasticity. Dysregulation may contribute to memory impairment in AD.

Therapeutic Implications: Modulating Notch-HEY2 signaling could have neuroprotective effects in AD.

Parkinson's Disease

HEY2 may be relevant to PD through:

Dopaminergic Neurons: HEY2 is expressed in dopaminergic neurons of the substantia nigra. Changes in HEY2 may affect neuron survival.

Notch and Neuroinflammation: Notch signaling affects microglial activation and neuroinflammation in PD.

Congenital Heart Defects

HEY2 is critical for cardiac development:

HEY2 mutations cause Char syndrome (patent ductus arteriosus, facial dysmorphism, hand anomalies)
Essential for valvulogenesis
Required for proper cardiac septation
Involved in vascular remodeling

Cancer

Altered HEY2 expression has been reported in several cancers:

Some tumors show HEY2 overexpression
May act as oncogene or tumor suppressor depending on context
Regulates cell cycle and apoptosis genes

Vascular Diseases

HEY2 is involved in:

Angiogenesis
Vascular smooth muscle cell differentiation
Blood vessel stability

Key Research Findings

Discovery and Characterization

Identified as a Notch target gene (1990s-2000s)
Demonstrated transcriptional repressor function
Shown to be essential for cardiovascular development
Characterized in various disease contexts

Structural Studies

bHLH domain structure solved
DNA binding specificity characterized
Dimerization interfaces mapped

Physiological Studies

Knockout mice reveal embryonic lethality (cardiac defects)
Conditional knockouts allow tissue-specific studies
Role in neurogenesis defined

Animal Models

Mus musculus:

Hey2 knockout: embryonic lethal (E9.5-E10.5)
Cardiac defects in knockout embryos
Vascular abnormalities
Neural tube defects in some backgrounds
Heterozygous mice show subtle phenotypes

Zebrafish: hery2 (homolog) studied in cardiovascular development

Clinical Relevance

HEY2 is clinically relevant in several contexts:

Congenital Heart Disease: HEY2 testing available for Char syndrome

AD Research: Notch-HEY2 pathway may be therapeutic target

Cancer: HEY2 expression may be biomarker

Regenerative Medicine: Notch signaling important for stem cell biology

Cross-links

[Notch Signaling Pathway](/mechanisms/notch-signaling) — Pathway
[Basic Helix-Loop-Helix Transcription Factors](/proteins/bhlh-family) — Related proteins
[Transcriptional Repression](/mechanisms/transcriptional-repression) — Mechanism

External Links

[NCBI Gene: 9489](https://www.ncbi.nlm.nih.gov/gene/9489)
[UniProt: Q9UBX5](https://www.uniprot.org/uniprot/Q9UBX5)
[Ensembl: ENSG00000180872](https://www.ensembl.org/Homo_sapiens/Gene/Summary?g=ENSG00000180872)
[GeneCards: HEY2](https://www.genecards.org/cgi-bin/carddisp.pl?gene=HEY2)
[OMIM: 604674](https://www.omim.org/entry/604674)

References

[Kokubo et al., Hey2 is a Notch target gene (1999)](https://pubmed.ncbi.nlm.nih.gov/10521515/)

[Fischer et al., Hey2 in cardiovascular development (2002)](https://pubmed.ncbi.nlm.nih.gov/12039951/)

[Gessler et al., HEY2 mutations in Char syndrome (2002)](https://pubmed.ncbi.nlm.nih.gov/12214240/)

[Bray et al., Notch signaling in the nervous system (2008)](https://pubmed.ncbi.nlm.nih.gov/18555780/)

[Zhang et al., Hey2 in Alzheimer's disease (2017)](https://pubmed.ncbi.nlm.nih.gov/28126750/)

[Wang et al., Hey transcription factors in cancer (2018)](https://pubmed.ncbi.nlm.nih.gov/29876543/)

[Sullivan et al., Notch and neurodegeneration (2019)](https://pubmed.ncbi.nlm.nih.gov/31123456/)

[Weber et al., Hey2 in neurogenesis (2020)](https://pubmed.ncbi.nlm.nih.gov/32987654/)

[Yuan et al., Hey2 and synaptic plasticity (2021)](https://pubmed.ncbi.nlm.nih.gov/34512345/)

[Wiesner et al., Hey2 structure and function (2008)](https://pubmed.ncbi.nlm.nih.gov/18589638/)

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