Optineurin is an important component in the neurobiology of neurodegenerative diseases. This page provides detailed information about its structure, function, and role in disease processes.
optineurin (OPTN, optic neuropathy-inducing protein) is a multifunctional adaptor protein that plays essential roles in selective autophagy, vesicular trafficking, nf-kb signaling regulation, and innate immune signaling. Encoded by the optn gene on chromosome 10p13, optineurin functions as a selective autophagy receptor for damaged mitochondrial-dynamics, intracellular bacteria, and protein aggregates, working in close partnership with [TBK1[/proteins/TBK1 kinase.[1] Mutations in OPTN cause both familial als and primary open-angle glaucoma (POAG), establishing optineurin as a critical link between neurodegeneration and selective autophagy dysfunction.[2] The convergence of OPTN and [TBK1[/proteins/TBK1 mutations in ALS has illuminated the central importance of autophagy receptor-kinase signaling in motor-neurons survival. [2:1]
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Optineurin is a 577-amino acid, ~67 kDa cytoplasmic protein with multiple protein-protein interaction domains:[3:1] [4]
| Property | Details | [5]
|----------|---------| [6]
| Gene | optn | [7]
| UniProt ID | Q96CV9 | [8]
| Molecular Weight | ~67 kDa | [9]
| Amino Acids | 577 | [10]
| Subcellular Localization | Cytoplasm, Golgi apparatus, autophagosomes, mitochondrial contact sites | [11]
| Protein Family | Selective autophagy receptors (SQSTM1-like) | [12]
Optineurin function is extensively regulated by post-translational modifications: [13]
| Modification | Site | Kinase/Enzyme | Effect | [14]
|-------------|------|---------------|--------|
| Phosphorylation | Ser177 | [TBK1[/proteins/TBK1 | Enhances LIR-LC3 binding (~20-fold) |
| Phosphorylation | Ser473 | TBK1 | Enhances UBAN-ubiquitin binding |
| Phosphorylation | Ser513 | TBK1 | Promotes IRF3 activation |
| Ubiquitination | Multiple Lys | HACE1, others | Regulates protein stability and interactions |
| Deubiquitination | Multiple Lys | CYLD | Negative regulation of nf-kb signaling |
Optineurin functions as a selective autophagy receptor for multiple cargo types:[6:1]
mitophagy: Optineurin is recruited to damaged mitochondria following pink1-protein/parkin-mediated ubiquitination of outer mitochondrial membrane proteins. The UBAN domain recognizes ubiquitin chains on mitochondria, while the LIR motif recruits autophagosomes. [TBK1[/proteins/TBK1 phosphorylation amplifies this process, creating a feed-forward signaling cascade that ensures efficient engulfment of damaged mitochondria. Optineurin is considered the dominant autophagy receptor for Parkin-dependent mitophagy in several cell types, more important than p62-sqstm1 or NDP52 in this context.
Xenophagy: Optineurin is a primary receptor for antibacterial autophagy, targeting ubiquitinated intracellular bacteria (Salmonella, Mycobacterium) for autophagic destruction. TBK1-mediated phosphorylation at Ser177 is required for efficient xenophagy.
Aggrephagy: Optineurin participates in clearance of ubiquitinated protein aggregates, complementing p62-sqstm1 and NBR1 in the autophagic degradation of misfolded proteins. This is particularly relevant in motor-neurons where tdp-43 and sod1-protein aggregates accumulate in ALS.
The optineurin-TBK1 interaction is central to selective autophagy. A 2024 study in The EMBO Journal revealed that optineurin provides a physical mitophagy contact site for TBK1 activation:[7:1]
This contact site model explains why both OPTN and TBK1 mutations cause ALS: disruption at either end of the optineurin-TBK1 axis impairs the mitophagy contact site and prevents efficient clearance of damaged mitochondria.
Optineurin participates in liquid-liquid-phase-separation (LLPS), forming dynamic biomolecular condensates that are critical for autophagy function. A 2024 study demonstrated that autophagy adaptors including optineurin form sheet-like liquid condensates on damaged mitochondria during Parkin-dependent mitophagy:[8:1]
This connects optineurin dysfunction to the broader theme of pathological phase transitions in neurodegenerative diseases, where proteins like tdp-43 and fus-protein undergo aberrant phase separation and aggregation.
Optineurin negatively regulates nf-kb signaling by competing with NEMO for ubiquitin chain binding. Through its UBAN domain, optineurin sequesters linear ubiquitin chains, preventing NEMO-mediated nf-kb activation. Loss of optineurin function leads to enhanced nf-kb-driven neuroinflammation, chronic inflammatory signaling, and increased production of pro-inflammatory cytokines including TNF-alpha, IL-1beta, and IL-6.
Optineurin interacts with Rab8, myosin VI, and huntingtin to regulate:
Beyond NF-kB, optineurin plays roles in type I interferon signaling through the cGAS-STING pathway. Optineurin promotes sting-pathway-mediated IRF3 activation via TBK1, contributing to antiviral defense and sterile inflammatory responses. Disruption of this function by ALS-causing mutations may contribute to dysregulated interferon signaling in Motor neurons Disease.[9:1]
OPTN mutations account for approximately 1–4% of familial als cases and some sporadic cases:[2:2]
Key ALS mutations:
Pathogenic mechanisms:
The convergence of OPTN, [TBK1[/proteins/TBK1, p62-sqstm1, and vcp mutations in ALS establishes autophagy dysfunction as a central disease mechanism, defining a "selective autophagy" subtype of ALS.
OPTN mutations were first identified as a cause of normal-tension glaucoma (NTG), a neurodegenerative disease of retinal ganglion cells (RGCs):[10:1]
The study of Optineurin 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.
Wild et al. Phosphorylation of the autophagy receptor optineurin restricts Salmonella growth, Science (2011). 2011. ↩︎
Maruyama et al. Mutations of optineurin in amyotrophic lateral sclerosis, Nature (2010). 2010. ↩︎ ↩︎ ↩︎
Ying & Bhatt, Optineurin — multifunctional roles in diseases and gene therapy, Trends in Molecular Medicine (2016). 2016. ↩︎ ↩︎
Richter et al. Phosphorylation of OPTN by TBK1 enhances its binding to Ub chains, PNAS (2016). 2016. ↩︎ ↩︎
Li et al. Structural insights into the ubiquitin recognition by OPTN and its regulation by TBK1, Autophagy (2018). 2018. ↩︎ ↩︎
Lazarou et al. The ubiquitin kinase PINK1 recruits autophagy receptors to induce mitophagy, Nature (2015). 2015. ↩︎ ↩︎
Yamano et al. Optineurin provides a mitophagy contact site for TBK1 activation, The EMBO Journal (2024). 2024. ↩︎ ↩︎
Yamano et al. Autophagy adaptors mediate Parkin-dependent mitophagy by forming sheet-like liquid condensates, The EMBO Journal (2024). 2024. ↩︎ ↩︎
Bakshi et al. Structural and functional perspectives of optineurin in autophagy, immune signaling, and cancer, Cells (2025). 2025. ↩︎ ↩︎
Rezaie et al. Adult-onset primary open-angle glaucoma caused by mutations in optineurin, Science (2002). 2002. ↩︎ ↩︎
Minegishi et al. Enhanced optineurin E50K-TBK1 interaction evokes protein insolubility and initiates POAG, Human Molecular Genetics (2013). 2013. ↩︎ ↩︎
Ito et al. RIPK1 mediates axonal degeneration by promoting inflammation and necroptosis in ALS, Science (2016). 2016. ↩︎ ↩︎
Nakazawa et al. Linear ubiquitination is involved in the pathogenesis of optineurin-associated ALS, Nature Communications (2016). 2016. ↩︎
Li et al. Structural insights into the interaction of optineurin and TBK1, Nature Communications (2016). 2016. ↩︎