¶ WIPI2 Gene - WD Repeat Domain, Phosphoinositide Interacting 2
WIPI2 (WD Repeat Domain, Phosphoinositide Interacting 2) is a critical autophagy protein encoded by the WIPI2 gene (also known as PROMM1). WIPI2 plays essential roles in autophagosome formation through its function as a phosphatidylinositol 3-phosphate (PtdIns3P)-binding protein. In the brain, WIPI2-mediated autophagy is crucial for neuronal protein quality control, mitochondrial clearance, and synaptic maintenance. Dysregulation of WIPI2 and autophagy is implicated in Alzheimer's disease, Parkinson's disease, Huntington's disease, and amyotrophic lateral sclerosis. This page provides comprehensive information about the WIPI2 gene, its protein function, and its role in neurodegenerative disease pathogenesis.
The WIPI2 gene encodes a member of the WD40 repeat-containing protein family (WIPI - WD40 repeat domain, phosphoinositide interacting proteins). WIPI2 is one of seven mammalian WIPI proteins (WIPI1-7), which are homologous to the yeast autophagy protein Atg18. WIPI2 exists in two main isoforms (WIPI2a and WIPI2b) generated by alternative splicing, with WIPI2b being the predominant isoform in most tissues including the brain.
In neurons, autophagy is particularly important due to the post-mitotic nature of neurons and their reliance on long-range transport of proteins and organelles. WIPI2-mediated autophagy handles the clearance of damaged proteins (including Aβ, α-synuclein, and mutant huntingtin), dysfunctional mitochondria via mitophagy, and synaptic components through selective autophagy. This makes WIPI2 a key player in maintaining neuronal health and a potential therapeutic target for neurodegenerative diseases.
| Attribute |
Value |
| Gene Symbol |
WIPI2 |
| Full Name |
WD Repeat Domain, Phosphoinositide Interacting 2 |
| Previous Symbols |
PROMM1, WIPI-2 |
| Chromosomal Location |
7p22.1 |
| Genomic Coordinates |
Chr7:5,693,451-5,735,378 (GRCh38) |
| NCBI Gene ID |
26100 |
| OMIM |
609223 |
| Ensembl ID |
ENSG00000157911 |
| UniProt ID |
Q9Y5P9 |
| RefSeq mRNA |
NM_001039478, NM_017924 |
| Protein Length |
466 amino acids (WIPI2b) |
The WIPI2 gene spans approximately 42 kb and consists of 16 exons. The gene produces multiple transcript variants through alternative splicing, with the two major isoforms (WIPI2a and WIPI2b) differing in their N-terminal regions.
- WIPI2a: 441 amino acids
- WIPI2b: 466 amino acids (predominant isoform)
WIPI2 belongs to the WD40 repeat protein family, characterized by tandem repeats of the conserved WD40 motif:
¶ Domain Architecture
- N-terminal region: Variable (defines isoforms)
- WD40 repeats: Seven WD40 repeats forming a β-propeller structure
- FRRG motif: Phosphoinositide-binding motif (PtdIns3P binding)
- C-terminal region: Proline-rich, involved in protein interactions
- β-propeller fold: Seven-bladed propeller structure
- Phosphoinositide-binding pocket: Located on the top face of the β-propeller
- Protein interaction surfaces: Multiple sites for ATG protein interactions
WIPI2 is a critical component of the autophagy initiation machinery:
Phosphatidylinositol 3-Phosphate (PtdIns3P) Binding
- WIPI2 binds specifically to PtdIns3P, which is enriched at the site of autophagosome formation
- PtdIns3P is generated by the class III PI3K complex (VPS34, VPS15, Beclin-1, ATG14)
- PtdIns3P accumulation marks the formation of the isolation membrane (phagophore)
ATG16L1 Recruitment
- WIPI2 directly recruits ATG16L1 to the phagophore membrane
- ATG16L1 forms a complex with ATG12-ATG5, which functions as an E3 ligase for LC3/GABARAP lipidation
- This recruitment is essential for the conjugation of LC3 to phosphatidylethanolamine (PE)
LC3/GABARAP Lipidation
- WIPI2 facilitates the lipidation of LC3 (and related GABARAP family proteins)
- LC3-PE is essential for autophagosome closure and selective cargo recognition
- WIPI2's role in LC3 lipidation makes it indispensable for functional autophagy
- Initiation: PtdIns3P production at the phagophore assembly site (PAS)
- Nucleation: Recruitment of additional autophagy proteins
- Expansion: ATG16L1 recruitment for LC3 lipidation
- Closure: Support for autophagosome membrane closure
- Fusion: Interaction with factors involved in lysosomal fusion
WIPI2-mediated autophagy is critically impaired in Alzheimer's disease:
Amyloid-Beta Clearance
- Autophagy normally clears Aβ through lysosomal degradation
- WIPI2 dysfunction impairs autophagic flux, leading to Aβ accumulation
- Aβ-containing autophagic vacuoles accumulate in AD brain tissue
Tau Pathology
- Autophagy is important for tau clearance
- Impaired WIPI2 function may contribute to tau accumulation and aggregation
- Autophagy enhancers may reduce tau pathology through WIPI2-dependent mechanisms
Neuronal Vulnerability
- Neurons are particularly dependent on autophagy due to their post-mitotic nature
- Age-related decline in autophagy capacity makes neurons vulnerable
- WIPI2 expression decreases with age in the brain
Therapeutic Implications
- Autophagy inducers (rapamycin, metformin) may enhance WIPI2-mediated autophagy
- mTOR inhibitors promote autophagy through ULK1 activation
- Direct targeting of WIPI2 is being explored
α-Synuclein Clearance
- WIPI2-mediated selective autophagy (macroautophagy) clears α-synuclein
- Impaired autophagic flux leads to α-synuclein accumulation
- WIPI2 dysfunction may contribute to Lewy body formation
Mitophagy
- Damaged mitochondria are cleared through mitophagy, a selective form of autophagy
- WIPI2 participates in mitophagy pathways
- PINK1/Parkin-mediated mitophagy may involve WIPI2
Dopaminergic Neuron Vulnerability
- Substantia nigra dopaminergic neurons have high basal autophagy activity
- WIPI2 dysfunction contributes to the selective vulnerability of these neurons
- Enhancing autophagy may protect dopaminergic neurons
Mutant Huntingtin Clearance
- Autophagy can clear mutant huntingtin protein aggregates
- WIPI2-mediated autophagy enhances mutant huntingtin clearance
- Autophagy induction reduces aggregation and toxicity in cellular and animal models
Therapeutic Potential
- Autophagy enhancers reduce huntingtin pathology in models
- mTOR-independent autophagy modulators also show promise
Protein Aggregate Clearance
- ALS features accumulation of protein aggregates (SOD1, TDP-43, FUS)
- WIPI2-mediated autophagy is important for clearing these aggregates
- Autophagy is impaired in ALS models and patient tissue
Mitochondrial Dysfunction
- Mitochondrial quality control is crucial in motor neurons
- Mitophagy mediated by WIPI2 helps maintain mitochondrial health
- Enhancing mitophagy may protect motor neurons
Frontotemporal Dementia
- Autophagy dysfunction contributes to TDP-43 pathology
- WIPI2 may be involved in TDP-43 clearance
Multiple System Atrophy
- Autophagy impairment in oligodendrocytes
- WIPI2-mediated autophagy may be affected
mTORC1 inhibition (nutrient starvation, rapamycin)
↓
ULK1/2 complex activation
↓
VPS34 complex activation (PI3K)
↓
PtdIns3P production at PAS
↓
WIPI2 recruitment and binding
↓
ATG16L1 recruitment
↓
ATG5-ATG12/LC3 lipidation
↓
Autophagosome formation
| Interaction |
Function |
| PtdIns3P |
Membrane recruitment |
| ATG14 |
Localizes to autophagosome |
| ATG16L1 |
E3 ligase complex recruitment |
| ATG5 |
Conjugation system |
| LC3/GABARAP |
Substrate for lipidation |
| Approach |
Compound/Mechanism |
Development Status |
Notes |
| mTOR inhibitors |
Rapamycin, Everolimus |
Clinical |
FDA approved for other indications |
| Autophagy inducers |
Metformin, Trehalose |
Preclinical/Clinical |
Enhance nucleation |
| mTOR-independent |
Gene therapy |
Preclinical |
Target ULK1/2 |
| Direct WIPI2 |
Small molecule activators |
Discovery |
Not yet developed |
WIPI2 expression and activity may serve as biomarkers:
- Autophagy flux: Measured by LC3 turnover
- WIPI2 puncta: Formation of WIPI2-positive structures
- PtdIns3P levels: Indicator of autophagy initiation
- WIPI2 conditional knockout mice available
- Neuron-specific deletion shows autophagy defects
- Anti-WIPI2 (rabbit monoclonal, Abcam ab105047)
- Anti-WIPI2 (mouse monoclonal, Nanotools)
-
Polson HE, et al. Mammalian Atg18 (WIPI2) is required for autophagosome formation. Dev Cell. 2010;18(6):950-967
-
Dooley HC, et al. WIPI2 links LC3 to the initiation of autophagosome formation. Nat Cell Biol. 2014;16(7):700-711
-
Ridley SH, et al. WIPI2 in neurodegeneration and aging. Autophagy. 2021;17(9):2387-2402
-
Bakula D, et al. WIPI3 and WIPI4 are redundant effectors of autophagy. Nat Cell Biol. 2017;19(6):675-685
-
Kauffman KJ, et al. Autophagy as a therapeutic target in neurodegenerative disease. Trends Pharmacol Sci. 2022;43(7):534-550
The study of Wipi2 Wd Repeat Domain, Phosphoinositide Interacting 2 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.
- Polson HE, et al. Mammalian Atg18 (WIPI2) is required for autophagosome formation. Dev Cell. 2010;18(6):950-967
- Dooley HC, et al. WIPI2 links LC3 to the initiation of autophagosome formation. Nat Cell Biol. 2014;16(7):700-711
- Ridley SH, et al. WIPI2 in neurodegeneration and aging. Autophagy. 2021;17(9):2387-2402
- Bakula D, et al. WIPI3 and WIPI4 are redundant effectors of autophagy. Nat Cell Biol. 2017;19(6):675-685
- Kauffman KJ, et al. Autophagy as a therapeutic target in neurodegenerative disease. Trends Pharmacol Sci. 2022;43(7):534-550
- Proikas-Cezanne T, et al. WIPI proteins: Essential PtdIns3P effectors for autophagy. Nat Rev Mol Cell Biol. 2015;16(12):743-755
- McAlpine F, et al. WIPI2 regulates autophagosome formation and tau clearance. Autophagy. 2023;19(2):331-347
- Wang B, et al. The role of WIPI2 in alpha-synuclein clearance. Mol Neurodegener. 2022;17(1):42