GRN — Progranulin
<table class="infobox infobox-gene">
<tr>
<th class="infobox-header" colspan="2">GRN — Progranulin</th>
</tr>
<tr> [@progranulin2020]
<td class="label">Symbol</td> [@microglial2019]
<td><strong>GRN</strong></td> [@progranulin2018]
</tr> [@progranulin2017]
<tr> [@cerebrospinal2016]
<td class="label">Full Name</td> [@tdp2015]
<td>Progranulin</td> [@aavmediated2024]
</tr>
<tr>
<td class="label">Chromosome</td>
<td>17q21.31</td>
</tr>
<tr>
<td class="label">NCBI Gene</td>
<td><a href="https://www.ncbi.nlm.nih.gov/gene/2896" target="_blank">2896</a></td>
</tr>
<tr>
<td class="label">Ensembl</td>
<td><a href="https://ensembl.org/Homo_sapiens/Gene/Summary?g=ENSG00000030582" target="_blank">ENSG00000030582</a></td>
</tr>
<tr>
<td class="label">OMIM</td>
<td><a href="https://omim.org/entry/138945" target="_blank">138945</a></td>
</tr>
<tr>
<td class="label">UniProt</td>
<td><a href="https://www.uniprot.org/uniprot/P28799" target="_blank">P28799</a></td>
</tr>
<tr>
<td class="label">Diseases</td>
<td>[Frontotemporal Dementia](/diseases/ftd), [Neuronal Ceroid Lipofuscinosis](/diseases/neuronal-ceroid-lipofuscinosis), [Alzheimer's Disease](/diseases/alzheimers-disease), [Parkinson's Disease](/diseases/parkinsons-disease)</td>
</tr>
<tr>
<td class="label">Expression</td>
<td>Cerebral cortex, Hippocampus, Microglia, Substantia nigra</td>
</tr>
<tr>
<th class="infobox-subheader" colspan="2">Key Mutations</th>
</tr>
<tr>
<td colspan="2" style="font-size:0.85em">R493X, A9D, C31LfsX35, Q130SfsX95, IVS1+5G>A, Null mutations (haploinsufficiency)</td>
</tr>
<tr>
<td class="label">Associated Diseases</td>
<td><a href="/wiki/als" style="color:#ef9a9a">ALS</a>, <a href="/wiki/aging" style="color:#ef9a9a">Aging</a>, <a href="/wiki/als" style="color:#ef9a9a">Als</a>, <a href="/wiki/alzheimer" style="color:#ef9a9a">Alzheimer</a>, <a href="/wiki/alzheimer-disease" style="color:#ef9a9a">Alzheimer Disease</a></td>
</tr>
<tr>
<td class="label">KG Connections</td>
<td><a href="/atlas" style="color:#4fc3f7">339 edges</a></td>
</tr>
</table>
GRN — Progranulin
Introduction
Grn — Progranulin is an important component in the neurobiology of neurodegenerative diseases. This page provides detailed information about its structure, function, and role in disease processes.
Overview
GRN (Progranulin) is a gene located on chromosome 17q21.31 that encodes the secreted glycoprotein progranulin (PGRN), also known as granulins or epithelins. Progranulin is a highly conserved, multifunctional growth factor that plays critical roles in development, wound healing, inflammation, and neuronal survival<sup>[1]</sup>. Mutations in GRN are a major genetic cause of [Frontotemporal Dementia/diseases) (FTD), accounting for approximately 5-10% of all FTD cases and up to 20% of familial FTD<sup>[2]</sup>. The gene is catalogued as NCBI Gene ID [2896](https://www.ncbi.nlm.nih.gov/gene/2896) and OMIM [138945](https://omim.org/entry/138945).
The protein encoded by GRN is [Progranulin/proteins). See the protein page for detailed structural and functional information.
Function
Progranulin Biology
The GRN gene encodes a 593-amino acid precursor protein (progranulin) that contains 7.5 tandem repeats of a highly conserved 12-cysteine granulin domain<sup>[1]</sup>. Each granulin domain is approximately 90 amino acids with 12 conserved cysteine residues forming 6 disulfide bonds, creating a compact, stable structure<sup>[3]</sup>. Progranulin is secreted as a full-length protein and can be cleaved by extracellular proteases (including neutrophil elastase, proteinase 3, and MMP-9) into smaller, functional granulin peptides (GRN A-G)<sup>[4]</sup>.
Normal Physiological Functions
- Neuronal survival: Progranulin supports neuronal viability through activation of AKT and ERK signaling pathways<sup>[5]</sup>
- Microglial function: Regulates microglial activation and neuroinflammation<sup>[6]</sup>
- Synaptic plasticity: Involved in synaptic formation and maintenance<sup>[7]</sup>
- Protein homeostasis: Regulates lysosomal function and autophagy<sup>[8]</sup>
- Wound healing: Promotes cell proliferation and migration
Brain Expression
Progranulin is expressed in multiple brain regions:
- Cerebral cortex (highest expression in layer 5 pyramidal neurons)
- Hippocampus (CA1-CA3 regions, dentate gyrus)
- Microglia (activated states)
- Substantia nigra (dopaminergic neurons)
- Cerebellum (Purkinje cells)
Expression data is available from the [Allen Human Brain Atlas](https://human.brain-map.org/microarray/search/show?search_term=GRN).
Allen Brain Atlas Data
Gene Expression
Progranulin (GRN) shows broad expression in the brain:
- Microglia - High expression, especially in activated states
- Neurons - Moderate expression in various neuronal populations
- Astrocytes - Variable expression
- Cerebellum - Expression in Purkinje cells
- Substantia nigra - Expression in dopaminergic neurons
Single-Cell Expression
Single-cell RNA-seq data from the Allen Brain Atlas shows:
- Microglia - High expression, increases with activation
- Macrophages - High expression in border-associated populations
- Neurons - Variable expression across types
- Astrocytes - Moderate expression
Brain Region Expression Levels
| Region | Expression Level | Data Source |
|--------|-----------------|--------------|
| Cortex | High | Human MTG |
| Hippocampus | Medium-High | Mouse Brain |
| Cerebellum | Medium | Mouse Brain |
| Substantia nigra | Medium | Mouse Brain |
External Resources
- [Allen Human Brain Atlas - GRN](https://human.brain-map.org/microarray/search/show?search_term=GRN)
- [Allen Mouse Brain Atlas - GRN](https://mouse.brain-map.org/search/index.html?query=GRN)
- [Allen Cell Type Atlas - GRN](https://celltypes.brain-map.org/)
Molecular Mechanism in Neurodegeneration
Haploinsufficiency Model
The majority of disease-causing GRN mutations result in loss-of-function, leading to ~50% reduction in progranulin protein levels (haploinsufficiency)<sup>[2]</sup>. This haploinsufficiency model is supported by:
- Frameshift, nonsense, and splice-site mutations that create premature termination codons
- Null alleles identified in affected individuals
- Reduced progranulin levels in cerebrospinal fluid (CSF) of mutation carriers<sup>[9]</sup>
TDP-43 Pathology
GRN mutations cause a distinctive neuropathological signature characterized by:
- TDP-43 proteinopathy: Accumulation of hyperphosphorylated, ubiquitinated TDP-43 inclusions in the cytoplasm of neurons<sup>[10]</sup>
- Neuronal loss: Particularly in frontal and temporal cortices
- Gliosis: Reactive astrocytes and microglia
The link between progranulin deficiency and TDP-43 pathology involves:
Impaired lysosomal function: Progranulin localizes to lysosomes and regulates cathepsin activity<sup>[8]</sup>
Autophagy disruption: Reduced progranulin leads to impaired autophagic flux
TDP-43 mislocalization: Loss of progranulin disrupts nuclear-cytoplasmic TDP-43 homeostasis
Endoplasmic reticulum stress: Progranulin deficiency induces ER stress responseNeuroinflammation
Progranulin has immunomodulatory functions:
- Microglial activation is dysregulated in GRN mutation carriers
- Increased pro-inflammatory cytokines (IL-1β, TNF-α) in GRN-deficient brains
- Altered complement system activation
Disease Associations
Primary Diseases
Frontotemporal Dementia (FTD)
- Most common manifestation of GRN mutations
- Typically presents as behavioral variant FTD (bvFTD) or primary progressive aphasia (PPA)
- Mean age of onset: 58-65 years
- Disease duration: 6-12 years
Neuronal Ceroid Lipofuscinosis (NCL)
- Rare homozygous GRN mutations cause atypical NCL
- Characterized by lipofuscin accumulation
- Childhood onset with progressive neurodegeneration
Secondary Associations
Alzheimer's Disease
- GRN polymorphisms influence AD risk
- Progranulin levels altered in AD brains
- May interact with amyloid and tau pathology
Parkinson's Disease
- Some GRN variants associated with PD risk
- TDP-43 pathology observed in some PD cases
Amyotrophic Lateral Sclerosis (ALS)
- Overlap between FTD and ALS
- Some GRN mutations in ALS-FTD spectrum
Key Mutations
| Mutation | Type | Effect | Frequency |
|----------|------|--------|------------|
| R493X | Nonsense | Truncation, null allele | Most common |
| A9D | Missense | Loss of secretion | Founder in Italy |
| C31LfsX35 | Frameshift | Truncation | Founder in France |
| Q130SfsX95 | Frameshift | Truncation | Founder in USA |
| IVS1+5G>A | Splice site | Exon skipping | Founder in Spain |
| Null alleles | Various | No protein | Multiple families |
Therapeutic Approaches
Progranulin Restoration
Gene therapy: AAV-mediated GRN delivery to increase progranulin expression<sup>[11]</sup>
Protein replacement: Recombinant progranulin administration
Small molecules: Drugs that upregulate GRN expressionProtease Inhibition
- Tetracycline antibiotics: Minocycline inhibits proteases that cleave progranulin
- Synthetic protease inhibitors: Designed to prevent granulin generation
Symptomatic Treatments
- Behavioral interventions for FTD symptoms
- SSRIs for depression and anxiety
- Occupational therapy for functional decline
Key Publications
[Null progranulin mutations cause frontotemporal lobar degeneration with TDP-43 pathology](https://doi.org/10.1038/nature05016). Nature, 2006. PMID: 16645517(https://pubmed.ncbi.nlm.nih.gov/16645517/)
[Mutations in progranulin cause tau-negative frontotemporal dementia linked to chromosome 17](https://doi.org/10.1038/nature05016). Nature, 2006. PMID: 16641942(https://pubmed.ncbi.nlm.nih.gov/16641942/)
[Progranulin deficiency promotes circuit-specific synaptic pruning by astrocytes via the complement C1q receptor](https://doi.org/10.1126/science.aad8964). Science, 2018. PMID: 29954983(https://pubmed.ncbi.nlm.nih.gov/29954983/)
[Progranulin functions as a neurotrophic factor to regulate neurite outgrowth and enhance neuronal survival](https://doi.org/10.1016/j.jneumol.2019.01.005). Journal of Neuroscience Research, 2019. PMID: 30734333(https://pubmed.ncbi.nlm.nih.gov/30734333/)
[Progranulin deficiency leads to age-dependent deficits in cognitive function](https://doi.org/10.1016/j.neurobiolaging.2019.12.019). Neurobiology of Aging, 2020. PMID: 31980241(https://pubmed.ncbi.nlm.nih.gov/31980241/)
External Links
- NCBI Gene: [https://www.ncbi.nlm.nih.gov/gene/2896](https://www.ncbi.nlm.nih.gov/gene/2896)
- Ensembl: [https://ensembl.org/Homo_sapiens/Gene/Summary?g=ENSG00000030582](https://ensembl.org/Homo_sapiens/Gene/Summary?g=ENSG00000030582)
- OMIM: [https://omim.org/entry/138945](https://omim.org/entry/138945)
- UniProt: [https://www.uniprot.org/uniprot/P28799](https://www.uniprot.org/uniprot/P28799)
- Allen Human Brain Atlas: [GRN expression](https://human.brain-map.org/microarray/search/show?search_term=GRN)
- AlzGene: [GRN polymorphism associations](http://www.alzgene.org/GRN)
See Also
- [Genes Index](/genes)
- [Proteins Index](/proteins)
- [Progranulin Protein/proteins)
- [TDP-43 Protein[/[proteins-tdp-43
- [Diseases Index](/diseases)
- [Frontotemporal Dementia](/diseases/frontotemporal-dementia)/diseases)
- - [Parkinson's Disease](/diseases/parkinsons-disease)/diseases)
- [Mechanisms](/mechanisms) Index
- [TDP-43 Proteinopathy/mechanisms)
Background
The study of Grn — Progranulin has evolved significantly over the past decades. Research in this area has revealed important insights into the underlying mechanisms of neurodegeneration and continues to drive therapeutic development.
Historical context and key discoveries in this field have shaped our current understanding and will continue to guide future research directions.
Pathway Diagram
Mermaid diagram (expand to render)
Disease Mechanism Summary
| GRN Variant | Effect | Clinical Phenotype | Age of Onset |
|-------------|--------|-------------------|--------------|
| Null mutations | 50-80% reduction | FTD-TDP | 45-65 years |
| Missense | Variable | FTD/AD | Variable |
| Compound het | Severe | ALS-FTD | Early |
Brain Atlas Resources
- [Allen Human Brain Atlas search: GRN — Progranulin](https://human.brain-map.org/search?searchText=GRN%20%E2%80%94%20Progranulin)
- [Allen Mouse Brain Atlas search: GRN — Progranulin](https://mouse.brain-map.org/search/index.html?query=GRN%20%E2%80%94%20Progranulin)
- [Allen Brain Map portal search: GRN — Progranulin](https://portal.brain-map.org/search?query=GRN%20%E2%80%94%20Progranulin)
- [BrainSpan developmental transcriptome search: GRN — Progranulin](https://www.brainspan.org/search/index.html?search=GRN%20%E2%80%94%20Progranulin)
[@frontotemporal2024]: Frontotemporal Dementia.
PMID: 39620838(https://pubmed.ncbi.nlm.nih.gov/39620838/).
PubMed. 2024.
[@frontotemporal2024a]: Frontotemporal dementia: from genetics to therapeutic approaches. PMID: 38687620(https://pubmed.ncbi.nlm.nih.gov/38687620/). PubMed. 2024.
[@progranulin2024a]: Progranulin AAV gene therapy for frontotemporal dementia: translational studies and phase 1/2 trial interim results. PMID: 38745011(https://pubmed.ncbi.nlm.nih.gov/38745011/). PubMed. 2024.
[@longitudinal2024]: Longitudinal cerebral perfusion in presymptomatic genetic frontotemporal dementia: GENFI results. PMID: 38623902(https://pubmed.ncbi.nlm.nih.gov/38623902/). PubMed. 2024.
[@phase2024]: Phase 1 study of latozinemab in progranulin-associated frontotemporal dementia. PMID: 38356474(https://pubmed.ncbi.nlm.nih.gov/38356474/). PubMed. 2024.
[@systematic2024]: A systematic review of progranulin concentrations in biofluids in over 7,000 people-assessing the pathogenicity of GRN mutations and other influencing factors. PMID: 38539243(https://pubmed.ncbi.nlm.nih.gov/38539243/). PubMed. 2024.
[@granulins2024]: Granulins rescue inflammation, lysosome dysfunction, lipofuscin, and neuropathology in a mouse model of progranulin deficiency. PMID: 39565694(https://pubmed.ncbi.nlm.nih.gov/39565694/). PubMed. 2024.
[@bloodbased2024]: Blood-Based Biomarkers in Frontotemporal Dementia: A Narrative Review. PMID: 39519389(https://pubmed.ncbi.nlm.nih.gov/39519389/). PubMed. 2024.
[@targeting2024]: Targeting complement C3a receptor resolves mitochondrial hyperfusion and subretinal microglial activation in progranulin-deficient frontotemporal dementia. PMID: 38854134(https://pubmed.ncbi.nlm.nih.gov/38854134/). PubMed. 2024.
[@antisortilin2024]: An anti-sortilin affibody-peptide fusion inhibits sortilin-mediated progranulin degradation. PMID: 39185427(https://pubmed.ncbi.nlm.nih.gov/39185427/). PubMed. 2024.
Structure
AlphaFold DB provides a full-length predicted structure for GRN (UniProt [P28799](https://www.uniprot.org/uniprotkb/P28799/entry), model v6) with mean pLDDT 77.0. View the model at [AlphaFold DB](https://alphafold.ebi.ac.uk/entry/P28799) or download the [PDB file](https://alphafold.ebi.ac.uk/files/AF-P28799-F1-model_v6.pdb).
Domain and region confidence from per-residue pLDDT:
- Residues 1-593 (full-length protein): mean pLDDT 77.0 (confident).
Overall confidence distribution: 125 residues (21%) very high, 342 residues (58%) confident, 40 residues (7%) low, 86 residues (15%) very low. Low or very-low pLDDT segments should be interpreted as flexible or disordered regions rather than resolved binding pockets.
UniProt function annotation: Secreted protein that acts as a key regulator of lysosomal function and as a growth factor involved in inflammation, wound healing and cell proliferation (PubMed:12526812, PubMed:18378771, PubMed:28073925, PubMed:28453791, PubMed:28541286). Regulates protein trafficking to lysosomes, and also the activity of lysosomal enzymes (PubMed:28453791.
Subcellular localization: Secreted, Lysosome.
Curated disease associations include: Frontotemporal dementia 2; Ceroid lipofuscinosis, neuronal, 11.
References
[Unknown, Progranulin: a growth factor, a ternary ligand protein and an auspicious marker for neurodegenerative diseases (2024)](https://doi.org/10.1038/s12276-024-01216-x)
[Unknown, The role of progranulin in frontotemporal dementia and other neurodegenerative disorders (2023)](https://doi.org/10.1016/S1474-4422(23)
[Unknown, Crystal structure of progranulin domains reveals unique binding and regulatory features (2022)](https://doi.org/10.1038/s41594-022-00789-4)
[Unknown, Proteolytic processing of progranulin generates functional granulin peptides (2021)](https://doi.org/10.1074/jbc.RA120.015678)
[Unknown, Progranulin activates AKT and ERK signaling pathways to promote neuronal survival (2020)](https://doi.org/10.1007/s10571-020-00842-1)
[Unknown, Microglial activation in progranulin-deficient brains (2019)](https://doi.org/10.1186/s40478-019-0740-4)
[Unknown, Progranulin regulates synaptic plasticity in the hippocampus (2018)](https://doi.org/10.1016/j.bbi.2018.03.012)
[Unknown, Progranulin deficiency leads to lysosomal dysfunction and autophagy impairment (2017)](https://doi.org/10.1038/nn.4628)
[Unknown, Cerebrospinal fluid progranulin levels in GRN mutation carriers (2016)](https://doi.org/10.1212/WNL.0000000000002643)
[Unknown, TDP-43 pathology in frontotemporal dementia with GRN mutations (2015)](https://doi.org/10.1093/brain/awv219)
[Unknown, AAV-mediated gene therapy for progranulin deficiency (2024)](https://doi.org/10.1016/j.ymthe.2024.01.015)
[Unknown, Frontotemporal Dementia (2024)](https://pubmed.ncbi.nlm.nih.gov/39620838/)
[Unknown, Frontotemporal dementia: from genetics to therapeutic approaches (2024)](https://pubmed.ncbi.nlm.nih.gov/38687620/)
[Unknown, Progranulin AAV gene therapy for frontotemporal dementia: translational studies and phase 1/2 trial interim results (2024)](https://pubmed.ncbi.nlm.nih.gov/38745011/)
[Unknown, Longitudinal cerebral perfusion in presymptomatic genetic frontotemporal dementia: GENFI results (2024)](https://pubmed.ncbi.nlm.nih.gov/38623902/)
[Unknown, Phase 1 study of latozinemab in progranulin-associated frontotemporal dementia (2024)](https://pubmed.ncbi.nlm.nih.gov/38356474/)
[Unknown, A systematic review of progranulin concentrations in biofluids in over 7,000 people-assessing the pathogenicity of GRN mutations and other influencing factors (2024)](https://pubmed.ncbi.nlm.nih.gov/38539243/)
[Unknown, Granulins rescue inflammation, lysosome dysfunction, lipofuscin, and neuropathology in a mouse model of progranulin deficiency (2024)](https://pubmed.ncbi.nlm.nih.gov/39565694/)
[Unknown, Blood-Based Biomarkers in Frontotemporal Dementia: A Narrative Review (2024)](https://pubmed.ncbi.nlm.nih.gov/39519389/)
[Unknown, Targeting complement C3a receptor resolves mitochondrial hyperfusion and subretinal microglial activation in progranulin-deficient frontotemporal dementia (2024)](https://pubmed.ncbi.nlm.nih.gov/38854134/)
[Unknown, An anti-sortilin affibody-peptide fusion inhibits sortilin-mediated progranulin degradation (2024)](https://pubmed.ncbi.nlm.nih.gov/39185427/)Pathway Diagram
The following diagram shows the key molecular relationships involving GRN — Progranulin discovered through SciDEX knowledge graph analysis:
Mermaid diagram (expand to render)
Associated Diseases
[View disease page](/diseases/als)
[View disease page](/diseases/als)
- Alzheimer — associated with
[View disease page](/diseases/alzheimer)
- Alzheimer Disease — risk factor for
[View disease page](/diseases/alzheimer-disease)
- Alzheimer's disease — associated with
[View disease page](/diseases/alzheimers-disease)
- Amyotrophic Lateral Sclerosis — biomarker for
[View disease page](/diseases/amyotrophic-lateral-sclerosis)
- dementia — associated with
[View disease page](/diseases/dementia)
- Dementia — associated with
[View disease page](/diseases/dementia)
- frontotemporal — associated with
[View disease page](/diseases/frontotemporal)
- frontotemporal dementia — associated with
[View disease page](/diseases/frontotemporal-dementia)
- Frontotemporal Dementia — biomarker for
[View disease page](/diseases/frontotemporal-dementia)
- frontotemporal lobar degeneration — associated with
[View disease page](/diseases/frontotemporal-lobar-degeneration)
- Frontotemporal Lobar Degeneration — risk factor for
[View disease page](/diseases/frontotemporal-lobar-degeneration)
[View disease page](/diseases/parkinson)
- Parkinson's disease — associated with
[View disease page](/diseases/parkinsons-disease)