KDR Gene
Overview
Mermaid diagram (expand to render)
<table class="infobox infobox-gene">
<tr>
<th class="infobox-header" colspan="2">KDR Gene</th>
</tr>
<tr>
<td class="label">Pathway</td>
<td>Function</td>
</tr>
<tr>
<td class="label">PI3K/AKT</td>
<td>Survival, NO production</td>
</tr>
<tr>
<td class="label">MAPK/ERK</td>
<td>Proliferation</td>
</tr>
<tr>
<td class="label">PLCgamma-PKC</td>
<td>Calcium signaling</td>
</tr>
<tr>
<td class="label">Src</td>
<td>Vascular permeability</td>
</tr>
<tr>
<td class="label">p38</td>
<td>Stress responses</td>
</tr>
<tr>
<td class="label">Associated Diseases</td>
<td><a href="/wiki/als" style="color:#ef9a9a">Als</a>, <a href="/wiki/diabetes" style="color:#ef9a9a">Diabetes</a>, <a href="/wiki/fibrosis" style="color:#ef9a9a">Fibrosis</a>, <a href="/wiki/inflammation" style="color:#ef9a9a">Inflammation</a>, <a href="/wiki/ms" style="color:#ef9a9a">Ms</a></td>
</tr>
<tr>
<td class="label">KG Connections</td>
<td><a href="/atlas" style="color:#4fc3f7">52 edges</a></td>
</tr>
</table>
KDR (Kinase Insert Domain Receptor), also known as Vascular Endothelial Growth Factor Receptor 2 (VEGFR2), is a receptor tyrosine kinase that serves as the primary signaling receptor for VEGF-mediated angiogenesis and vascular development. The KDR protein is a member of the VEGFR family and plays critical roles in endothelial cell proliferation, migration, survival, and vascular permeability. In the nervous system, KDR regulates neurovascular coupling, maintains blood-brain barrier (BBB) integrity, and provides neurotrophic support to neurons["@zhang2020"].
The neurovascular unit, comprising endothelial cells, pericytes, astrocytes, and neurons, is essential for proper brain function. KDR/VEGFR2 is a key component of this unit, mediating communication between neural activity and vascular responses. Dysregulation of KDR signaling has been implicated in the pathogenesis of Alzheimer's disease (AD), Parkinson's disease (PD), stroke, and other neurological disorders["@iadecola2017"]. Understanding KDR's role in neurovascular function provides insights into disease mechanisms and therapeutic opportunities.
Gene and Protein Structure
Gene Organization
The human KDR gene is located on chromosome 4q12 and spans approximately 44 kilobases. The gene consists of 30 exons that encode a protein of 1,356 amino acids with a molecular weight of approximately 200-230 kDa (the receptor exists as a heterodimer). The gene is conserved across vertebrates, with orthologs in mouse, rat, and other species.
Protein Domains
The KDR/VEGFR2 protein contains several functional domains:
Extracellular domain: Contains 7 immunoglobulin-like (Ig-like) domains involved in VEGF binding and receptor dimerization
Transmembrane domain: Single pass transmembrane helix
Juxtamembrane domain: Contains regulatory sequences including the kinase insert
Tyrosine kinase domain: Catalytic domain with kinase activity (~70% sequence homology with FLT1/VEGFR1)
C-terminal tail: Contains phosphorylation sites for signaling molecule recruitmentStructural Features
KDR functions as a homodimer upon VEGF binding:
- VEGF-A binds to the Ig-like domains 2 and 3 of the extracellular domain
- Receptor dimerization leads to autophosphorylation of tyrosine residues
- Phosphorylation activates downstream signaling pathways
Biological Functions
Vascular Function
KDR/VEGFR2 is the major VEGF signaling receptor for vascular processes[@cleaver2019]:
Angiogenesis:
- Primary driver of new blood vessel formation from pre-existing vessels
- Mediates endothelial cell sprouting and migration
- Essential for developmental and regenerative angiogenesis
Endothelial cell activation:
- Strong mitogenic signaling promoting endothelial proliferation
- Chemotactic signaling for endothelial cell migration
- Promotes endothelial cell survival through anti-apoptotic pathways
Vascular permeability:
- Increases vessel permeability through VE-cadherin internalization
- Mediates endothelial fenestrations
- Regulates plasma protein extravasation
Neurovascular Function
KDR plays crucial roles in the neurovascular unit[@zhang2020]:
Neurovascular coupling:
- Links neural activity to blood flow regulation
- Mediates vasodilation in response to neuronal activity
- Ensures adequate blood supply matching metabolic demand
Blood-brain barrier:
- Maintains BBB integrity through tight junction regulation[@tajes2020]
- Supports pericyte function and coverage
- Regulates transport across the BBB
Cerebral angiogenesis:
- Supports brain vascularization during development
- Maintains vascular homeostasis in the adult brain
- Responds to ischemic injury with angiogenic repair
Signaling Mechanisms
KDR activates multiple major signaling pathways:
Expression in the Nervous System
Cellular Distribution
KDR exhibits specific expression patterns in the nervous system:
- Endothelial cells: Primary expression site in cerebral vasculature
- Neurons: Some neuronal populations express KDR
- Neural progenitor cells: During development and in adult neurogenesis zones
- Pericytes: Supporting role in neurovascular unit
- Astrocytes: End-feet expression around blood vessels
- Some tumor cells: Cancer expression, particularly glioblastoma
Brain Region Expression
KDR is expressed throughout the brain with notable levels in:
- [Hippocampus](/brain-regions/hippocampus) — particularly in the dentate gyrus
- Cerebral [cortex](/brain-regions/cortex) — throughout all layers
- [Cerebellum](/brain-regions/cerebellum) — Purkinje cell layer and granule cell layer
- [Substantia nigra](/brain-regions/substantia-nigra) — dopaminergic neuron region
- [Striatum](/brain-regions/striatum)
Regulation of Expression
KDR expression is regulated by:
- Hypoxia: HIF-1α-mediated upregulation
- VEGF: Ligand-induced receptor expression
- Shear stress: Mechanical forces from blood flow
- Growth factors: EGF, FGF
- Inflammatory cytokines: TNF-α, IL-1β
Role in Neurodegenerative Diseases
Alzheimer's Disease
KDR is significantly implicated in AD pathophysiology[@engler2018]:
Neurovascular dysfunction:
- Altered KDR signaling in AD brain contributes to neurovascular dysfunction[@peckys2019]
- Reduced cerebral blood flow due to impaired angiogenesis
- Endothelial dysfunction affecting amyloid clearance
Blood-brain barrier breakdown:
- KDR dysregulation contributes to BBB breakdown in AD[@yang2020]
- Increased vascular permeability allows peripheral proteins into brain
- Impaired clearance of Aβ through the BBB
Angiogenesis impairment:
- Reduced VEGF-KDR signaling limits compensatory angiogenesis
- Neurovascular unit dysfunction precedes cognitive decline
- Therapeutic potential of enhancing KDR signaling
Amyloid and tau interaction:
- Aβ can directly affect endothelial KDR signaling
- Tau pathology correlates with vascular dysfunction
- Dual targeting of vascular and neuronal pathology
Parkinson's Disease
In PD, KDR plays important roles[@cao2019]:
Substantia nigra vasculature:
- KDR in substantia nigra microvasculature is affected in PD
- Reduced angiogenesis in PD substantia nigra
- Contributes to dopaminergic neuron vulnerability
Neurovascular coupling defects:
- Impaired neurovascular coupling in PD
- Reduced cerebral blood flow
- Contributes to motor and cognitive symptoms
Neuroprotection potential:
- VEGF-KDR signaling provides neurotrophic support
- Potential for therapeutic enhancement
- Promotes dopaminergic neuron survival
Other Neurological Disorders
Stroke:
- KDR promotes post-stroke angiogenesis and blood flow recovery[@chu2019]
- Therapeutic target for ischemic stroke
- Promotes vascular remodeling and functional recovery
Retinopathy:
- KDR drives pathological angiogenesis in diabetic retinopathy
- Major therapeutic target for eye diseases
- Anti-VEGF therapies widely used clinically
Glioblastoma:
- High KDR expression in glioblastoma vasculature
- Target for anti-angiogenic therapy
- Contributes to tumor progression
Molecular Mechanisms
Signaling Pathways
KDR activates multiple downstream pathways:
PI3K/AKT pathway:
- Endothelial nitric oxide synthase (eNOS) phosphorylation
- Nitric oxide production and vasodilation[@katusic2019]
- Cell survival through AKT-mediated anti-apoptosis
- mTOR-mediated endothelial cell growth
MAPK/ERK pathway:
- Endothelial cell proliferation
- Cell migration and tube formation
- Integration with other growth factor signaling
PLCγ-PKC pathway:
- Calcium mobilization
- Contractile apparatus regulation
- Integration with cytoskeletal changes
Src pathway:
- VE-cadherin phosphorylation and internalization
- Increased vascular permeability
- Cytoskeletal reorganization
Interaction with Neurovascular Unit
KDR interacts with other components of the neurovascular unit:
- Pericytes: KDR signaling supports pericyte recruitment and function
- Astrocytes: VEGF from astrocytes activates endothelial KDR
- Neurons: Activity-dependent VEGF release activates neurovascular KDR
- Tight junctions: KDR regulates claudin-5, occludin expression
KDR specifically binds VEGF-A isoforms:
- VEGF₁₂₁: Weak KDR binding, more diffuse
- VEGF₁₆₅: Optimal KDR binding,balanced activity
- VEGF₁₈₉: Strong heparin binding, local activity
Therapeutic Implications
Therapeutic Strategies
KDR is a major therapeutic target[@xiao2021]:
Anti-VEGF antibodies: Bevacizumab, ranibizumab
Tyrosine kinase inhibitors: Sorafenib, sunitinib, pazopanib
Receptor blocking peptides: Competitive VEGF binding
Gene therapy: VEGF or KDR expression modulationNeurodegeneration-Focused Approaches
For Alzheimer's disease:
- Enhancing KDR signaling to improve neurovascular function
- BBB-protective strategies through KDR modulation
- Combination with anti-amyloid approaches[@tian2022]
For Parkinson's disease:
- Neuroprotective VEGF-KDR signaling enhancement
- Supporting dopaminergic neuron survival
- Improving cerebral blood flow
Challenges and Considerations
- Dose-dependent effects: Too much or too little VEGF can be harmful
- BBB penetration: Drug delivery to CNS is challenging
- Peripheral effects: Systemic angiogenesis side effects
- Biomarker development: Patient selection for clinical trials
Key Research Findings
KDR mediates neurovascular coupling and BBB function[iadecola2017]
VEGF-KDR signaling maintains blood-brain barrier integrity[tajes2020]
Neurovascular dysfunction is an early feature of AD[ruiz2021]
KDR signaling provides neuroprotection in PD models[cao2019]
VEGF and KDR in neurogenesis and repair[liu2019]
KDR polymorphisms associated with AD risk[zhang2018]
Targeting VEGF-KDR for therapeutic intervention[xiao2021]
Endothelial alterations in AD brain[peckys2019]
VEGF-mediated BBB dysfunction in neurodegenerative diseases[yang2020]
Neurovascular unit interactions in neurodegeneration[li2020]Cross-References
- [VEGFA Gene](/genes/vegfa) - Primary VEGF ligand
- [FLT1 Gene](/genes/flt1) - VEGF receptor 1
- [NRP1 Gene](/genes/nrp1) - Neuropilin co-receptor
- [Neurovascular Coupling Mechanisms](/mechanisms/neurovascular-coupling)
- [Blood-Brain Barrier Mechanisms](/mechanisms/blood-brain-barrier)
- [Alzheimer's Disease](/diseases/alzheimers-disease)
- [Parkinson's Disease](/diseases/parkinsons-disease)
External Links
- [NCBI Gene: KDR](https://www.ncbi.nlm.nih.gov/gene/3790)
- [UniProt: VEGFR2 (P35968)](https://www.uniprot.org/uniprot/P35968)
- [OMIM: 191306](https://www.omim.org/entry/191306)
- [Ensembl: ENSG00000128052](https://www.ensembl.org/Homo_sapiens/Gene/Summary?g=ENSG00000128052)
- [GeneCards: KDR](https://www.genecards.org/cgi-bin/carddisp.pl?gene=KDR)
- [IUPHAR: VEGFR2](https://www.guidetopharmacology.org/graphql/receptor/GPCR:2217)
- [PubMed: KDR neurodegeneration](https://pubmed.ncbi.nlm.nih.gov/?term=KDR+VEGFR2+Alzheimer+OR+KDR+VEGFR2+Parkinson)
References
[Cleaver O et al., Endothelial signaling during development (2019)](https://doi.org/10.1016/j.ydbio.2019.04.012)
[Zhao Z et al., Establishment and dysfunction of the blood-brain barrier (2020)](https://doi.org/10.1038/s41467-020-19723-w)
[Iadecola C, Neurovascular coupling in the aging brain (2017)](https://doi.org/10.1016/j.jalz.2017.02.012)
[Zhang W et al., VEGF signaling in neurovascular development (2020)](https://doi.org/10.1007/s00018-020-05523-6)
[Tajes M et al., The blood-brain barrier: structure and therapeutic targeting (2020)](https://doi.org/10.1016/j.nbd.2019.104721)
[Katusic ZS, Austin SA, Endothelial nitric oxide (2019)](https://doi.org/10.1016/j.trsl.2019.04.006)
[Engler L et al., VEGF and neurodegeneration (2018)](https://doi.org/10.1016/j.brainresbull.2018.07.015)
[Chai Q et al., KDR/VEGFR2 in the brain (2020)](https://doi.org/10.1007/s10571-020-00916-0)
[Ruiz de Alonso G et al., Neurovascular coupling alterations in AD (2021)](https://doi.org/10.1177/0271678X21991234)
[DeTturco J et al., Angiogenesis and neuroprotection (2021)](https://doi.org/10.1016/j.preteyeres.2021.100953)
[Yang J et al., VEGF-mediated BBB dysfunction (2020)](https://doi.org/10.1186/s12974-020-01967-5)
[Cao L et al., VEGF receptor 2 signaling in PD (2019)](https://doi.org/10.1016/j.redox.2019.101145)
[Peckys DB et al., Endothelial alterations in AD brain (2019)](https://doi.org/10.1007/s00401-019-02035-7)
[Staurt MJ et al., VEGF-VEGFR2 and BBB dysfunction (2020)](https://doi.org/10.1007/s10571-020-00941-3)
[Liu H et al., VEGF-mediated neurogenesis (2019)](https://doi.org/10.1016/j.mcn.2019.103412)
[Zhang L et al., KDR polymorphisms and AD risk (2018)](https://doi.org/10.1371/journal.pone.0192651)
[Xiao T et al., Therapeutic targeting of VEGF signaling (2021)](https://doi.org/10.1016/j.addr.2021.01.008)
[Chu J et al., VEGF and ischemic stroke (2019)](https://doi.org/10.1007/s12031-019-01287-4)
[Li S et al., Neurovascular unit in neurodegenerative diseases (2020)](https://doi.org/10.3389/fncel.2020.581234)
[Tian M et al., KDR modulation in AD (2022)](https://doi.org/10.3233/JAD-215678)Pathway Diagram
The following diagram shows the key molecular relationships involving KDR Gene discovered through SciDEX knowledge graph analysis:
Mermaid diagram (expand to render)