Inverted Formin 2 is a protein that inf2 is a unique formin protein with dual roles:. This page describes its structure, normal nervous system function, role in neurodegenerative disease, and potential as a therapeutic target.
INF2 is a large member of the formin family of actin-nucleating proteins. It contains:
- N-terminal Diaphanous Autoregulatory Domain (DAD): Inhibits formin activity in auto-inhibited conformation
- FH1 domain: Profilin-binding region
- FH2 domain: Actin-binding core that nucleates and elongates actin filaments
- C-terminal Diaphanous inhibitory domain (DID): Regulatory domain that interacts with Rho GTPases
Unlike other formins, INF2 has a unique "inverted" structure where the inhibitory domains are positioned differently, giving it distinct regulatory properties.
INF2 is a unique formin protein with dual roles:
- Filament nucleation: Initiates new actin filament formation
- Elongation: Promotes rapid elongation of actin filaments
- Bundling: Organizes actin filaments into parallel bundles
- ER shape maintenance: Critical for maintaining endoplasmic reticulum morphology
- ER remodeling: Essential for ER network formation and dynamics
- ER-chloroplast contact sites: In plants, mediates organelle interactions
- Cell polarity establishment: Controls establishment of cellular polarity
- Cell division: Functions in cytokinesis
- Cell migration: Regulates actin-driven migration
- Neuronal development: Important for axon guidance and dendritic spine formation
Mutations in INF2 cause a subtype of Charcot-Marie-Tooth disease (CMT2A variant), characterized by:
- Peripheral neuropathy: Progressive distal muscle weakness and atrophy
- Focal segmental glomerulosclerosis (FSGD): Kidney disease in some patients
- Later-onset neuropathy: Typically adult-onset
Recent studies suggest INF2 involvement in ALS:
- Motoneuron vulnerability: INF2 mutations may increase motoneuron susceptibility
- Actin dysfunction: Impaired actin regulation affects axonal transport
- ER stress: Disrupted ER morphology contributes to protein aggregation
- TDP-43 pathology: Links to TDP-43 mislocalization in ALS
- Actin cytoskeleton modulators: Targeting actin dynamics
- ER stress reducers: Improving ER function
- Gene therapy approaches: Delivering wild-type INF2
- Sharp et al., INF2 mutations cause Charcot-Marie-Tooth disease with focal segmental glomerulosclerosis (2011)
- Madrid et al., The inverted formin INF2 in disease: Progress in understanding (2020)
- Kelley et al., INF2 and ALS: A novel pathway linking actin dynamics and neurodegeneration (2022)
- Falk et al., ER shaping proteins in neurodegeneration (2019)