title: Brain-Derived Neurotrophic Factor (BDNF) Protein
| Property | Value |
|---|---|
| Protein Name | Brain-Derived Neurotrophic Factor |
| Gene | BDNF |
| UniProt ID | P23560 |
| Molecular Weight | ~13 kDa (monomer), ~26 kDa (dimer) |
| Length | 119 amino acids (mature), 256 (precursor) |
| Structure | Cysteine knot fold, homodimer |
| PDB Entries | 1BND, 1B8M, 3OJ3, 7A0J |
| Expression | Brain, CNS neurons, astrocytes, microglia |
Brain-derived neurotrophic factor (BDNF) is a member of the neurotrophin family of growth factors that plays crucial roles in the survival, development, and function of neurons in the central and peripheral nervous systems. BDNF is critical for synaptic plasticity, memory formation, and neuronal survival[1]. BDNF is one of the most widely expressed neurotrophins in the mammalian brain, with particularly high levels in the hippocampus, cortex, and basal forebrain — regions essential for learning and memory.
BDNF exerts its effects through binding to two classes of receptors: TrkB (tropomyosin receptor kinase B) with high affinity, and p75NTR (p75 neurotrophin receptor) with lower affinity. The balance between these receptor signaling pathways determines whether BDNF promotes neuronal survival, differentiation, or in some contexts, apoptosis.
| Region | Residues | Description |
|---|---|---|
| Signal peptide | 1-19 | Targets protein for secretory pathway |
| Pro-domain | 20-120 | Contains propeptide, mediates folding |
| Mature domain | 121-256 | Active form, forms homodimers |
The crystal structure of BDNF reveals:
| Trigger | Secretion Type | Mechanism |
|---|---|---|
| Neuronal activity | Activity-dependent | Ca²⁺-dependent exocytosis |
| Depolarization | Activity-dependent | Voltage-gated calcium channels |
| Glutamate | Activity-dependent | NMDA receptor activation |
| Cytokines | Constitutive | Inflammatory modulation |
| Property | Value |
|---|---|
| Gene | NTRK2 |
| Isoforms | Full-length (TrkB-FL), TrkB-T1 (truncated) |
| Signaling | PI3K/AKT, MAPK/ERK, PLCγ |
PI3K/AKT pathway
MAPK/ERK pathway
PLCγ pathway
BDNF prevents apoptosis in developing and mature neurons through:
BDNF is essential for both short-term and long-term synaptic modifications[2]:
| Type | Mechanism | BDNF Role |
|---|---|---|
| LTP | Long-term potentiation | Required for induction and maintenance |
| LTD | Long-term depression | Modulates plasticity thresholds |
| Homeostatic plasticity | Synaptic scaling | Regulates neurotransmitter release |
BDNF promotes:
BDNF stimulates:
BDNF levels are significantly reduced in AD brains[3]:
| Region | BDNF Change | Correlation |
|---|---|---|
| Hippocampus | 50-70% reduction | Memory impairment |
| Cortex | 30-50% reduction | Cognitive decline |
| CSF | Variable | Disease progression |
| Strategy | Approach | Status |
|---|---|---|
| Recombinant BDNF | Protein delivery | Preclinical |
| TrkB agonists | Small molecules | Clinical trials |
| Gene therapy | AAV-BDNF | Phase 1/2 |
| Exercise | Endogenous increase | Proven |
| Dietary restriction | Endogenous increase | Evidence |
BDNF supports the survival of dopaminergic neurons in the substantia nigra pars compacta:
| Finding | Significance |
|---|---|
| Reduced BDNF in PD SNc | Associated with neuron loss |
| Reduced TrkB signaling | Contributes to progression |
| BDNF polymorphism (Val66Met) | Modifies PD risk |
BDNF is significantly reduced in Huntington's disease due to multiple mechanisms[4]:
| Mechanism | Effect |
|---|---|
| Transcriptional impairment | mutant huntingtin interferes with REST/CoREST |
| Reduced transport | Impaired axonal trafficking to striatum |
| Decreased synthesis | Reduced cortical BDNF production |
| Agent | Mechanism | Development Status |
|---|---|---|
| 7,8-DHF | TrkB agonist | Preclinical |
| R13 | BDNF mimetic | Preclinical |
| Amitriptyline | Increases BDNF | Approved (off-label) |
| SSRIs | Increase BDNF | Approved |
AAV-mediated BDNF delivery:
Physical exercise is one of the most effective ways to increase endogenous BDNF:
| Sample | Measure | Utility |
|---|---|---|
| Serum | Mature BDNF | Correlates with cognition |
| CSF | Pro-BDNF/mature ratio | Disease state |
| Platelets | BDNF content | Peripheral marker |
| Interactor | Type | Function |
|---|---|---|
| TrkB | Receptor | Primary signaling receptor |
| p75NTR | Receptor | Apoptosis/survival modulation |
| Sortilin | Co-receptor | Pro-BDNF internalization |
| Heparin | Binding | Stabilization, localization |
Huang & Reichardt. Neurotrophins: Roles in neuronal development and function. Annual Review of Neuroscience (2001). 2001. ↩︎
Lu et al. BDNF-based synaptic repair as a disease-modifying strategy. Nature Neuroscience (2013). 2013. ↩︎
Palomer et al. BDNF Signaling in Alzheimer's Disease: From Risk Genes to Pathogenic Mechanisms. Trends in Neurosciences (2022). 2022. ↩︎
Zuccato & Cattaneo. Role of BDNF in Huntington's disease. Progress in Neurobiology (2009). 2009. ↩︎