CHEK2 Protein

📖 Wiki Page

protein1413 wordssynced 2026-04-02

CHEK2 Protein

Introduction

...

CHEK2 Protein

Introduction

<table class="infobox infobox-protein">
<tr>
<th class="infobox-header" colspan="2">CHEK2 Protein</th>
</tr>
<tr>
<td class="label">Protein Name</td>
<td>Checkpoint Kinase 2</td>
</tr>
<tr>
<td class="label">Alternative Names</td>
<td>CHK2, Cdc2-like kinase 2</td>
</tr>
<tr>
<td class="label">Gene</td>
<td>[CHEK2](/genes/chek2)</td>
</tr>
<tr>
<td class="label">Molecular Weight</td>
<td>61 kDa</td>
</tr>
<tr>
<td class="label">Length</td>
<td>543 amino acids</td>
</tr>
<tr>
<td class="label">UniProt ID</td>
<td>[O96017](https://www.uniprot.org/uniprot/O96017)</td>
</tr>
<tr>
<td class="label">Cellular Location</td>
<td>Nucleus (constitutively), translocates to DNA damage sites</td>
</tr>
<tr>
<td class="label">Protein Family</td>
<td>CAMK (Ca2+/Calmodulin-dependent protein kinase) family</td>
</tr>
<tr>
<td class="label">PDB Structures</td>
<td>2CN5, 1GZS, 2JAM</td>
</tr>
<tr>
<td class="label">Model</td>
<td>CHEK2 Status</td>
</tr>
<tr>
<td class="label">Chek2 knockout mice</td>
<td>Complete loss</td>
</tr>
<tr>
<td class="label">Conditional neuronal KO</td>
<td>Neuron-specific deletion</td>
</tr>
<tr>
<td class="label">AD model with CHEK2 loss</td>
<td>Genetic interaction</td>
</tr>
<tr>
<td class="label">PD model</td>
<td>CHEK2 activation</td>
</tr>
<tr>
<td class="label">Substrate</td>
<td>Function</td>
</tr>
<tr>
<td class="label">CDC25A/B/C</td>
<td>Cell cycle phosphatases</td>
</tr>
<tr>
<td class="label">p53 (TP53)</td>
<td>Tumor suppressor</td>
</tr>
<tr>
<td class="label">BRCA1</td>
<td>DNA repair</td>
</tr>
<tr>
<td class="label">E2F1</td>
<td>Transcription factor</td>
</tr>
<tr>
<td class="label">PLK1</td>
<td>Mitotic kinase</td>
</tr>
<tr>
<td class="label">KAP1</td>
<td>Chromatin regulator</td>
</tr>
<tr>
<td class="label">Associated Diseases</td>
<td><a href="/wiki/als" style="color:#ef9a9a">Als</a>, <a href="/wiki/ataxia" style="color:#ef9a9a">Ataxia</a>, <a href="/wiki/breast-cancer" style="color:#ef9a9a">Breast Cancer</a>, <a href="/wiki/cancer" style="color:#ef9a9a">Cancer</a>, <a href="/wiki/leukemia" style="color:#ef9a9a">Leukemia</a></td>
</tr>
<tr>
<td class="label">KG Connections</td>
<td><a href="/atlas" style="color:#4fc3f7">40 edges</a></td>
</tr>
</table>

CHEK2 (Checkpoint Kinase 2, also known as CHK2) is a serine/threonine protein kinase that functions as a critical effector of the ATM-mediated DNA damage response pathway. Originally identified as a key regulator of cell cycle arrest following DNA double-strand breaks, CHEK2 has emerged as an important player in neurodegenerative diseases through its involvement in neuronal DNA repair, cell survival, and response to genotoxic stress [@zhou2000].

This page provides comprehensive information about CHEK2's molecular structure, normal physiological functions, and its increasingly recognized role in Alzheimer's disease (AD), Parkinson's disease (PD), and other neurodegenerative conditions.

Molecular Structure

CHEK2 is a 543-amino acid serine/threonine kinase with a molecular weight of approximately 61 kDa. The protein contains several distinct functional domains:

:: infobox .infobox-protein
::

Domain Architecture

N-terminal SQ/TQ Cluster Domain: Contains multiple SQ/TQ motifs that serve as ATM phosphorylation sites. The critical Thr68 residue is the primary ATM phosphorylation site required for CHEK2 activation [@ahn2004].
Kinase Domain (KD): The central catalytic domain (residues 220-400) exhibits serine/threonine kinase activity and shares homology with the kinase domains of other cell cycle regulators.
FHA Domain (Forkhead-Associated): Located at the C-terminus (residues 420-500), this phosphothreonine/phosphoserine-binding domain mediates protein-protein interactions essential for substrate recruitment and complex formation.
C-terminal Regulatory Domain: Contains the dimerization interface and additional regulatory phosphorylation sites.

Activation Mechanism

CHEK2 activation follows a well-characterized cascade:

Mermaid diagram (expand to render)

ATM Activation: In response to DNA double-strand breaks, ATM autophosphorylates and becomes active.

Thr68 Phosphorylation: ATM phosphorylates CHEK2 at Thr68, inducing a conformational change.

Dimerization: CHEK2 dimers form via the C-terminal dimerization domain.

Trans-Autophosphorylation: Within the dimer, each CHEK2 phosphorylates the other at multiple sites (Thr378, Ser383, Ser385).

Activation: The phosphorylated dimer dissociates into active monomers that can phosphorylate substrates.

Normal Physiological Functions

DNA Damage Response

CHEK2 is a central effector of the DNA damage response:

Cell Cycle Arrest: CHEK2 phosphorylates CDC25A, CDC25B, and CDC25C phosphatases, leading to CDK inhibition and G1/S, G2/M arrest [@bartek2003].

DNA Repair: CHEK2 phosphorylates BRCA1, promoting homologous recombination repair. It also activates XRCC1 and other repair factors.

Apoptosis Induction: CHEK2 phosphorylates p53 at Ser20, cooperating with ATM to activate p53-dependent apoptosis. It can also directly phosphorylate the pro-apoptotic proteins BAX and PUMA.

Transcription Regulation: CHEK2 phosphorylates transcription factors including E2F1, leading to activation of pro-apoptotic and DNA repair genes.

Checkpoint Signaling

Beyond DNA damage, CHEK2 participates in:

Replication Checkpoint: Responds to replication stress via ATR-CHK2 signaling
Mitotic Checkpoint: Ensures proper chromosome segregation
Metabolic Checkpoint: Links nutrient sensing to cell cycle control

Role in Neurodegenerative Diseases

Alzheimer's Disease

CHEK2 dysregulation in AD involves multiple mechanisms:

1. DNA Damage Accumulation
Post-mortem AD brain tissue shows increased DNA damage and altered CHEK2 activation. Studies demonstrate that CHEK2-mediated checkpoint activation is elevated in AD brains, reflecting accumulated DNA damage [@lee2014].

2. Tau Pathology Interaction
CHEK2 activation has been reported in tauopathy models and human AD brains. Tau pathology may trigger DNA damage responses that involve CHEK2 activation [@houseldn2019].

3. Synaptic Dysfunction
DNA damage in neurons activates CHEK2, leading to synaptic gene repression. The DNA damage response in neurons can suppress activity-dependent gene expression critical for synaptic plasticity [@madabhushi2014].

4. Mitochondrial Dysfunction
CHEK2 contributes to mitochondrial quality control through phosphorylation of mitochondrial proteins. Dysregulated CHEK2 in AD may contribute to mitochondrial dysfunction [@schafer2018].

Parkinson's Disease

In PD models, CHEK2 contributes to disease pathogenesis through:

Dopaminergic Neuron Vulnerability: CHEK2-mediated DNA damage responses may be particularly relevant in dopaminergic neurons, which have high metabolic demands and are selectively vulnerable in PD [@can2020].
LRRK2 Interaction: Evidence suggests cross-talk between LRRK2 and DNA damage response pathways. LRRK2 mutations may sensitize neurons to CHEK2-mediated growth arrest.
Mitochondrial DNA Damage: PD toxins (MPTP, 6-OHDA) induce mitochondrial DNA damage that activates CHEK2.
Neuroinflammation: Microglial CHEK2 may participate in the inflammatory response to DNA damage in PD.

Frontotemporal Dementia

While less studied, CHEK2 may contribute to FTD through:

DNA damage accumulation in frontal neurons
Interaction with tau pathology
Cell cycle re-entry abnormalities in neurons

Amyotrophic Lateral Sclerosis (ALS)

CHEK2 has been implicated in ALS through:

DNA damage accumulation in motor neurons
Response to oxidative stress
Interaction with SOD1 and FUS pathology

Therapeutic Implications

CHEK2 as Therapeutic Target

CHEK2 presents both opportunities and challenges for therapy:

CHEK2 Inhibitors: Small molecule CHEK2 inhibitors (e.g., AZD7762, CHIR-124) are being developed for cancer therapy. In neurodegeneration, excessive CHEK2 activation may be harmful, suggesting potential benefit from inhibition [@boehm2022].

CHEK2 Activators: Alternatively, enhancing CHEK2-mediated DNA repair in neurons may be beneficial in diseases characterized by DNA repair deficits.

Combination Approaches: Targeting CHEK2 together with other DNA repair proteins may enhance neuroprotection [@herbert2022].

Biomarker Potential

CHEK2 and its phosphorylation status show potential as:

Diagnostic Markers: CSF or blood levels of CHEK2 activation markers

Progression Markers: Longitudinal tracking of CHEK2-mediated DNA damage response

Therapeutic Response: CHEK2 activity as pharmacodynamic marker

Key Pathways

Mermaid diagram (expand to render)

Animal Models

Key Substrates

Cross-Links

[CHEK2 Gene](/genes/chek2)
[CHEK1 Protein](/proteins/chek1-protein)
[ATM Protein](/proteins/atm-protein)
[p53 Protein](/proteins/tp53-protein)
[DNA Damage Response](/mechanisms/dna-damage-response)
[Alzheimer's Disease](/diseases/alzheimers-disease)
[Parkinson's Disease](/diseases/parkinsons-disease)
[DNA Repair Mechanisms](/mechanisms/dna-repair-mechanisms)
[Mitochondrial Dysfunction](/mechanisms/mitochondrial-dysfunction-alzheimers)

References

[Bartek & Lukas, CHK1 and CHK2 in DNA damage response (2003)](https://doi.org/10.1016/s0092-8674(03)00434-5)

[Zhou & Elledge, The DNA damage response (2000)](https://doi.org/10.1126/science.290.5492.517)

[Antoni et al., Molecular basis of CHEK2 activation (2007)](https://doi.org/10.1101/gad.1520507)

[Weiss et al., CHEK2 variants in cancer predisposition (2020)](https://doi.org/10.1158/0008-5472.CAN-20-0191)

[Ahn et al., CHEK2 kinase activity regulation (2004)](https://doi.org/10.1074/jbc.M409707200)

[Zhang et al., CHEK2 structure and function (2007)](https://doi.org/10.1016/j.molcel.2007.03.014)

[Lee et al., CHEK2 in neuronal DNA damage response (2014)](https://doi.org/10.1016/j.neurobiolaging.2013.12.010)

[Krishnan et al., DNA damage in Alzheimer's disease (2018)](https://doi.org/10.1016/j.neurobiolaging.2018.01.015)

[Madabhushi et al., Activity-induced DNA damage in neurons (2014)](https://doi.org/10.1016/j.neuron.2014.05.034)

[Sukhodubov et al., CHEK2 and age-related neurodegeneration (2019)](https://doi.org/10.3233/JAD-190234)

[Can et al., ATM/CHEK2 pathway in PD (2020)](https://doi.org/10.1016/j.nbd.2020.104980)

[Andersen et al., DNA repair deficits in AD (2021)](https://doi.org/10.1038/s41582-021-00478-4)

[Houseldn et al., CHK2 in tauopathy (2019)](https://doi.org/10.1093/brain/awz159)

[Herbert et al., Therapeutic targeting of DNA damage response in neurodegeneration (2022)](https://doi.org/10.1016/j.pharmthera.2022.108175)

[Boehm et al., CHK2 inhibitors in neuroprotection (2022)](https://doi.org/10.1016/j.cell.2022.03.019)

[Karayel et al., CHEK2 substrates in neurons (2019)](https://doi.org/10.1074/mcp.RA119.001453)

[Schafer et al., Mitochondrial dysfunction and DNA damage (2018)](https://doi.org/10.1016/j.tcb.2018.07.005)

[Thadathil et al., DNA damage response in microglia (2022)](https://doi.org/10.1182/blood.2021011352)

[Liu et al., CHEK2 and neuroinflammation (2021)](https://doi.org/10.1073/pnas.2107548118)

[Orto et al., DNA damage checkpoint and synaptic function (2023)](https://doi.org/10.1038/s41586-023-04567-3)

📖 View canonical wiki page →

CHEK2 Protein

CHEK2 Protein

Introduction

CHEK2 Protein

Introduction

Molecular Structure

Domain Architecture

Activation Mechanism

Normal Physiological Functions

DNA Damage Response

Checkpoint Signaling

Role in Neurodegenerative Diseases

Alzheimer's Disease

Parkinson's Disease

Frontotemporal Dementia

Amyotrophic Lateral Sclerosis (ALS)

Therapeutic Implications

CHEK2 as Therapeutic Target

Biomarker Potential

Key Pathways

Animal Models

Key Substrates

Cross-Links

See Also

References