Microglial TBK1 Deficiency Triggers Senescence-Associated Secretory Phenotype i…

Loss-of-function mutations in TBK1, a established risk factor for familial FTD, may trap microglia in a senescent, pro-inflammatory state characterized by SASP, analogous to the mechanism established in ALS. This microglial senescence could drive cortical neurodegeneration and accelerate disease progression in FTD. The prediction is that TBK1-deficient microglia in FTD models will exhibit upregulated senescence markers and a neurotoxic secretome.

Analogy rationale: TBK1 is a shared genetic risk factor for both ALS and FTD, and the mechanistic link between TBK1 loss and microglial senescence demonstrated in ALS likely extends to FTD given overlapping TDP-43 pathology and neuroinflammatory signatures in both diseases.

Disanalogies: FTD primarily involves frontal and temporal cortical regions whereas ALS affects motor neurons; the regional specificity of microglial senescence and the relative contribution of microglia versus neurons may differ between diseases.

Falsifiable prediction: Conditional knockout of TBK1 in microglia (Cx3cr1-Cre; Tbk1 flox/flox) in a FTD mouse model (e.g., Grn knockout or MAPT tauopathy) will yield increased p21/CDKN1A expression, elevated IL-6 and IL-1β secretion, and accelerated cortical neuronal loss compared to mice with intact TBK1.

This hypothesis was generated from h-31ca9240f9fc in ALS — judge it on its own merits but acknowledge the source.