Neurofilament Light Chain (NF-L)

Neurofilament Light Chain (NF-L)

<table class="infobox infobox-protein">
<tr>
<th class="infobox-header" colspan="2">Neurofilament Light Chain (NF-L)</th>
</tr>
<tr> [@feneberg2021]
<td class="label">Gene</td>
<td>[NEFL](/genes/nfl)</td>
</tr>
<tr>
<td class="label">UniProt</td>
<td><a href="https://www.uniprot.org/uniprot/P07196" target="_blank">P07196</a></td>
</tr>
<tr>
<td class="label">PDB</td>
<td><a href="https://www.rcsb.org/structure/1QDE" target="_blank">1QDE</a>, <a href="https://www.rcsb.org/structure/2N3P" target="_blank">2N3P</a></td>
</tr>
<tr>
<td class="label">Mol. Weight</td>
<td>61.5 kDa</td>
</tr>
<tr>
<td class="label">Localization</td>
<td>Axon, neuronal cytoplasm</td>
</tr>
<tr>
<td class="label">Family</td>
<td>Intermediate filament family</td>
</tr>
<tr>
<td class="label">Diseases</td>
<td>[Parkinson's Disease](/diseases/parkinsons-disease), [ALS](/diseases/als), [Alzheimer's Disease](/diseases/alzheimers), [Charcot-Marie-Tooth Disease](/diseases/charcot-marie-tooth)</td>
</tr>
</table>

Neurofilament Light Chain (NF-L)

Overview

[Neurofilament Light](/biomarkers/neurofilament-light-chain-nfl) Chain (NF-L), also known as NEFL, is a neuronal intermediate filament protein encoded by the [NEFL](/genes/nfl) gene on chromosome 8p21. NF-L is the most abundant neurofilament subunit and forms the core structural backbone of neuronal intermediate filaments in axons [@lee2022].

Neurofilament Light Chain (NF-L)

<table class="infobox infobox-protein">
<tr>
<th class="infobox-header" colspan="2">Neurofilament Light Chain (NF-L)</th>
</tr>
<tr> [@feneberg2021]
<td class="label">Gene</td>
<td>[NEFL](/genes/nfl)</td>
</tr>
<tr>
<td class="label">UniProt</td>
<td><a href="https://www.uniprot.org/uniprot/P07196" target="_blank">P07196</a></td>
</tr>
<tr>
<td class="label">PDB</td>
<td><a href="https://www.rcsb.org/structure/1QDE" target="_blank">1QDE</a>, <a href="https://www.rcsb.org/structure/2N3P" target="_blank">2N3P</a></td>
</tr>
<tr>
<td class="label">Mol. Weight</td>
<td>61.5 kDa</td>
</tr>
<tr>
<td class="label">Localization</td>
<td>Axon, neuronal cytoplasm</td>
</tr>
<tr>
<td class="label">Family</td>
<td>Intermediate filament family</td>
</tr>
<tr>
<td class="label">Diseases</td>
<td>[Parkinson's Disease](/diseases/parkinsons-disease), [ALS](/diseases/als), [Alzheimer's Disease](/diseases/alzheimers), [Charcot-Marie-Tooth Disease](/diseases/charcot-marie-tooth)</td>
</tr>
</table>

Neurofilament Light Chain (NF-L)

Overview

[Neurofilament Light](/biomarkers/neurofilament-light-chain-nfl) Chain (NF-L), also known as NEFL, is a neuronal intermediate filament protein encoded by the [NEFL](/genes/nfl) gene on chromosome 8p21. NF-L is the most abundant neurofilament subunit and forms the core structural backbone of neuronal intermediate filaments in axons [@lee2022].

NF-L is a critical component of the neuronal cytoskeleton, providing structural support and regulating axonal caliber. It is expressed exclusively in [neurons](/entities/neurons), primarily in large myelinated axons. NF-L is one of the most extensively studied biomarkers for axonal damage in neurodegenerative diseases, as it is released into cerebrospinal fluid and blood upon neuronal injury [@petzold2023].

Domain Structure

NF-L is a typical intermediate filament protein with three major domains:

Head Domain (1-86)

• N-terminal non-helical domain
• Contains phosphorylation sites
• Regulates filament assembly

Central Rod Domain (87-400)

• Alpha-helical coiled-coil structure
• Highly conserved across intermediate filaments
• Responsible for dimer formation
• Contains the helix start and termination motifs

Tail Domain (401-543)

• C-terminal domain with variable length
• Contains phosphorylation sites (Ser/Thr)
• Projects from filament surface
• Interacts with other neurofilament subunits
• Regulates spacing between filaments

Normal Function in the Nervous System

Axonal Structure and Support

• NF-L forms the core structural element of neurofilaments
• Provides tensile strength to axons
• Maintains axonal diameter, which directly correlates with conduction velocity
• NF-L null mice show reduced axonal caliber and slowed nerve conduction

Assembly and Polymerization

• NF-L forms heteropolymers with NF-M (NEFM) and NF-H (NEFH)
• Initial assembly as tetramers, then higher-order structures
• Phosphorylation regulates assembly state and spacing
• Proper neurofilament transport requires post-translational modifications

Interaction with Other Proteins

• Binds to plectin for cytoskeletal cross-linking
• Interacts with MAPs (Microtubule-Associated Proteins)
• Associates with voltage-gated sodium channels at nodes of Ranvier
• Links to actin microfilaments via scaffolding proteins

Role in Neurodegeneration

Biomarker for Axonal Damage

• CSF NF-L: Elevated in ALS, PD, AD, MS, and other neurodegenerative conditions
• Blood NF-L: Serum NF-L correlates with CSF levels and disease progression
• FDA-approved biomarker for ALS disease monitoring
• Predictive of conversion from prodromal to manifest disease

Mutations and Disease

• NEFL mutations cause Charcot-Marie-Tooth disease type 2E (CMT2E)
• Mutations lead to neuropathy and axonal degeneration
• Some mutations disrupt neurofilament assembly
• NF-L accumulation in aggresomes seen in some neurodegenerative conditions

Axonal Transport Defects

• Neurofilament accumulation in proximal axons is a hallmark of many neurodegenerative diseases
• Impaired axonal transport leads to neurofilament compaction
• Seen in ALS, PD, and experimental models of axonal degeneration
• NF-L fragmentation detected in vulnerable brain regions

Therapeutic Implications

• NF-L levels used for patient stratification and drug response monitoring
• NF-L lowering strategies being explored for neuroprotection
• Gene therapy approaches targeting NEFL expression

Therapeutic Targeting

Biomarker-Driven Trials

• NF-L used as enrollment criterion in ALS clinical trials
• Serves as pharmacodynamic biomarker for drug efficacy
• Helps identify responders vs non-responders
• Enables earlier readouts than clinical endpoints

Experimental Approaches

• Antisense oligonucleotides targeting NEFL being developed
• Modulation of neurofilament phosphorylation pathways
• Small molecules to improve axonal transport
• Gene therapy for NEFL mutations in CMT2E

Key Publications

See Also

• [NEFL Gene](/genes/nfl)

External Links

• [GeneCards: NEFL](https://www.genecards.org/cgi-bin/carddisp.pl?gene=NEFL)

References

Protein Interaction Network

Related Hypotheses

From the [SciDEX Exchange](/exchange) — scored by multi-agent debate

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• [Blood-Brain Barrier SPM Shuttle System](/hypothesis/h-959a4677) — <span style="color:#81c784;font-weight:600">0.75</span> · Target: TFRC
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• [Targeted Butyrate Supplementation for Microglial Phenotype Modulation](/hypothesis/h-3d545f4e) — <span style="color:#81c784;font-weight:600">0.72</span> · Target: GPR109A
• [Vagal Afferent Microbial Signal Modulation](/hypothesis/h-ee1df336) — <span style="color:#81c784;font-weight:600">0.71</span> · Target: GLP1R, BDNF
• [Selective TLR4 Modulation to Prevent Gut-Derived Neuroinflammatory Priming](/hypothesis/h-f3fb3b91) — <span style="color:#81c784;font-weight:600">0.67</span> · Target: TLR4
• [Enhancing Vagal Cholinergic Signaling to Restore Gut-Brain Anti-Inflammatory Communication](/hypothesis/h-a4e259e0) — <span style="color:#81c784;font-weight:600">0.65</span> · Target: CHRNA7
• [Targeting Bacterial Curli Fibrils to Prevent α-Synuclein Cross-Seeding](/hypothesis/h-8b7727c1) — <span style="color:#81c784;font-weight:600">0.64</span> · Target: CSGA

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• [Neuroinflammation resolution mechanisms and pro-resolving mediators](/analysis/SDA-2026-04-01-gap-014) &#x1f504;
• [What are the mechanisms by which gut microbiome dysbiosis influences Parkinson&#x27;s disease pathogenesi](/analysis/SDA-2026-04-01-gap-20260401-225149) &#x1f504;
• [What are the mechanisms by which gut microbiome dysbiosis influences Parkinson&#x27;s disease pathogenesi](/analysis/SDA-2026-04-01-gap-20260401-225155) &#x1f504;

Pathway Diagram

The following diagram shows the key molecular relationships involving Neurofilament Light Chain (NF-L) discovered through SciDEX knowledge graph analysis: