Neurons with granulovacuolar degeneration bodies are resilient to tau-induced protein synthesis impairment.

In Alzheimer's disease, many surviving neurons with tau pathology contain granulovacuolar degeneration bodies (GVBs), neuron-specific lysosomal structures induced by pathological tau assemblies. This could indicate a neuroprotective role for GVBs; however, the mechanism of GVB formation and its functional implications are elusive. Here, we demonstrate that casein kinase 1δ (CK1δ) activity is required for GVB formation. CK1δ is sequestered in the GVB during this process in an autophagy-dependent manner. We show that neurons with GVBs (GVB(+)) are resilient to tau-induced impairment of global protein synthesis and are protected against tau-mediated neurodegeneration. GVB(+) neurons do not exhibit differential activation of transient translational stress responses but have increased ribosomal content. Unlike neurons without GVBs, GVB(+) neurons fully retain the capacity to induce long-term potentiation-induced protein synthesis in the presence of tau pathology. Our results have identified CK1δ as a key regulator of GVB formation that confers a protective neuron-specific stress response to tau pathology. These findings provide opportunities for targeting neuronal resilience in tauopathies.