This synthesis documents the causal chain from TBK1 loss-of-function mutations to selective autophagy impairment to neuroinflammation and ALS/FTD. The TBK1 causal chain connects two critical cellular pathways — selective autophagy and innate immunity — and represents a significant therapeutic target.
This chain is part of our broader Gene-Mechanism-Therapy Causal Chains synthesis and complements our TBK1 Gene, OPTN, and SQSTM1/p62 pages.
| Element | Details |
|---|---|
| Gene | TBK1 - TANK-binding kinase 1 |
| Chromosome | 12q14.2 |
| Inheritance | Autosomal dominant (haploinsufficiency) |
| Prevalence | ~3-5% familial ALS, ~3-5% familial FTD |
| Key Variants | E696K, I397T, R357X, various LOF mutations |
| Mechanism | Loss-of-function → haploinsufficiency |
Genetic Evidence:
TBK1 phosphorylates critical autophagy receptors:
| Receptor | TBK1 Phosphorylation Site | Functional Effect |
|---|---|---|
| OPTN | Ser473 | Enhanced ubiquitin chain binding |
| SQSTM1/p62 | Ser403 | Increased cargo recognition |
| NDP52 (CALCOCO2) | Multiple | Mitochondrial recruitment |
Mechanism: TBK1 loss impairs phosphorylation of these receptors, reducing their ability to bind ubiquitinated cargo and recruit autophagosomes. This creates a bottleneck in selective autophagy[4][5].
TBK1 deficiency in microglia induces:
| Disease | Key Features |
|---|---|
| ALS | Motor neuron loss, progressive paralysis |
| FTD | Behavioral variant, language deficits |
| ALS/FTD | Overlapping syndrome |
| Approach | Status | Agent |
|---|---|---|
| mTOR inhibition | Preclinical | Rapamycin |
| TFEB activation | Preclinical | Trehalose, TFEB agonists |
| USP30 inhibition | Preclinical | Enhance mitophagy |
| Approach | Status | Agent |
|---|---|---|
| AAV-TBK1 | Preclinical | Restore TBK1 expression |
| OPTN modulators | Preclinical | Bypass TBK1 |
| Target | Status | Agent |
|---|---|---|
| Autophagy inducers | Preclinical | Rapamycin, trehalose |
| Neuroinflammation | Research | C3aR antagonists |
| Therapy | Target | Stage | Company |
|---|---|---|---|
| Autophagy inducers | mTOR/TFEB | Preclinical | Various |
| Gene therapy | TBK1 | Preclinical | Research |
TBK1 acts downstream of PINK1/Parkin in mitophagy:
See: PINK1/Parkin Mitophagy Pathway
TBK1 normally regulates cGAS-STING-mediated interferon responses:
See: cGAS-STING Neurodegeneration
Cirulli ET, et al. "Exome sequencing in amyotrophic lateral sclerosis identifies risk genes and pathways". Science. 2015. ↩︎
Freischmidt A, et al. "Haploinsufficiency of TBK1 causes familial ALS and fronto-temporal dementia". Nat Neurosci. 2015. ↩︎
Gijselinck I, et al. "Loss of TBK1 is a frequent cause of frontotemporal dementia in a Belgian cohort". Neurology. 2015. ↩︎
Matsumoto G, et al. "TBK1 controls autophagosomal engulfment of polyubiquitinated mitochondria through p62/SQSTM1 phosphorylation". Hum Mol Genet. 2015. ↩︎
Richter B, et al. "Phosphorylation of OPTN by TBK1 enhances its binding to Ub chains and promotes selective autophagy of damaged mitochondria". PNAS. 2016. ↩︎
Bhargava P, et al. "ALS/FTD-linked TBK1 deficiency in microglia induces an aged-like microglial signature". Nat Commun. 2025. ↩︎