Fasting Triggers Brain Synapse Cleanup via Newly Identified RAB5B Pathway
Nutrient stress activates a RAB5B-driven autophagy route that rapidly remodels synaptic proteins, linking diet to brain maintenance.
Resumen
Researchers at the University of Cologne discovered that nutrient stress — particularly serum withdrawal mimicking fasting — triggers rapid autophagy at brain synapses within 1–2 hours. This process is orchestrated by a protein called RAB5B, which recruits the cellular machinery needed to tag and degrade damaged or excess synaptic proteins. Importantly, simply blocking mTORC1 (a common longevity target) did not replicate the same remodeling effect. A fasting-mimicking diet produced overlapping synaptic protein changes seen during starvation-induced autophagy, suggesting dietary interventions can meaningfully reshape the synaptic proteome. These findings reveal a previously unrecognized trafficking pathway connecting nutrient sensing to synaptic quality control, with potential implications for neurological aging and brain health.
Resumen detallado
Synaptic health is foundational to cognition and neurological function, yet how neurons manage protein quality control under metabolic stress has remained poorly understood. This study addresses that gap by mapping the molecular machinery linking nutrient deprivation to synaptic proteome remodeling — a process critical for long-term brain maintenance.
The research team used serum withdrawal as a model of nutrient stress in neurons, alongside mTORC1 inhibition and amino acid restriction for comparison. They combined live imaging, proteomics, and genetic tools to track autophagy activation and cargo delivery at synaptic compartments.
Key findings show that nutrient stress rapidly activates synaptic autophagy within 1–2 hours via RAB5B-positive endosomal compartments. RAB5B coordinates the recruitment of LC3 lipidation machinery — essential for autophagosome formation — in a dynein-dependent manner. Live imaging confirmed enhanced co-trafficking of RAB5B with ATG16L1 and increased ATG5 mobility upon serum withdrawal, indicating tightly regulated, spatiotemporal delivery of autophagy components to synapses.
Strikingly, mTORC1 inhibition — widely studied as a longevity intervention — produced only limited synaptic proteome remodeling compared to nutrient stress. Restriction of mTORC1-activating amino acids similarly failed to induce comparable changes. However, a fasting-mimicking diet did produce synaptic proteome shifts overlapping with starvation-induced autophagy cargo, lending translational relevance to dietary fasting strategies.
These results identify RAB5B as a central node linking metabolic sensing to synaptic degradation. For longevity science, this suggests that the quality and composition of dietary interventions — not simply mTOR suppression — may determine the extent of beneficial synaptic remodeling. Caveats include reliance on in vitro nutrient stress models and the need for in vivo validation across aging contexts.
Hallazgos clave
- Nutrient stress activates synaptic autophagy within 1–2 hours via RAB5B-positive endosomal compartments.
- RAB5B recruits LC3 lipidation machinery to synapses in a dynein-dependent manner during fasting stress.
- mTORC1 inhibition alone produces limited synaptic proteome remodeling compared to full nutrient stress.
- A fasting-mimicking diet induces synaptic protein changes overlapping with starvation-driven autophagy cargo.
- Nutrient deprivation dampens neuronal activity, linking metabolic state directly to synaptic function.
Metodología
The study used in vitro neuronal models subjected to serum withdrawal, mTORC1 inhibition, and amino acid restriction to model nutrient stress. Live imaging tracked RAB5B, ATG16L1, and ATG5 dynamics at synapses, while proteomics profiled synaptic protein remodeling. A fasting-mimicking diet condition was included to assess translational relevance.
Limitaciones del estudio
The primary models rely on in vitro nutrient stress (serum withdrawal), which may not fully recapitulate physiological fasting in vivo. The specific cargo proteins remodeled and their functional consequences for cognition require further characterization. Translation to aging human neurons or animal aging models has not yet been demonstrated.
¿Te ha gustado este resumen?
Recibe la última investigación sobre longevidad en tu bandeja de entrada cada semana.
Introduce tu correo electrónico para suscribirte: