Biology subjects

Freiwald, A.

Publications and source records attributed to Freiwald, A..

3 recordsLinked to original sources

bioRxiv2026

Bro1-Mediated Trafficking Couples TOR Signalling to Cellular Metabolism and Longevity

Adaptation to nutrient availability requires coordination between growth control, metabolism, and intracellular trafficking. In eukaryotes, inhibition of Target of Rapamycin (TOR) signalling robustly promotes stress resistance and longevity, yet how reduced growth signalling is coupled to organelle dynamics and proteome remodelling remains unclear. Here, we identify the conserved ESCRT-associated protein Bro1 as a central integrator of TOR signalling, vacuolar trafficking, and metabolic adaptation. Using fission yeast, we show that Bro1 is required for normal lifespan and for the global proteomic reprogramming that accompanies TOR inhibition. In Bro1 mutant cells, repression of ribosome biogenesis is uncoupled from activation of catabolic, vacuolar, and metabolic pathways, resulting in an altered metabolic state characterised by elevated lipid metabolism and increased abundance of nutrient transporters. Mechanistically, Bro1 promotes TOR-dependent cargo deubiquitination, vacuolar trafficking, and turnover of plasma membrane hexose transporters and enables appropriate nuclear relocalisation of the transcriptional repressor Scr1. In the absence of Bro1, nutrient transporters persist at the cell surface despite TOR inhibition, conferring resistance to TOR inhibitors while impairing stress responses and reducing lifespan. Together, our findings establish Bro1 as a key coordinator linking ESCRT-mediated endosomal-vacuolar trafficking to TOR-dependent metabolic control. By coupling growth suppression to enhanced recycling and cellular maintenance, Bro1 enables the transition from growth to longevity-promoting states, revealing a mechanism connecting intracellular trafficking, metabolism, and ageing.

genetics↗

bioRxiv2022

Cell-cell metabolite exchange creates a pro-survival metabolic environment that extends lifespan

Metabolism is fundamentally intertwined with the ageing process. We here report that a key determinant of cellular lifespan is not only nutrient supply and intracellular metabolism, but also metabolite exchange interactions that occur between cells. Studying chronological ageing in yeast, we observed that metabolites exported by young, exponentially growing, cells are re- imported during the stationary phase when cells age chronologically, indicating the existence of cross-generational metabolic interactions. We then used self-establishing metabolically cooperating communities (SeMeCos) to boost cell-cell metabolic interactions and observed a significant lifespan extension. A search for the underlying mechanisms, coupling SeMeCos, metabolic profiling, proteomics and genome-scale metabolic modelling, attributed a specific role to methionine consumer cells. These cells were enriched over time, adopted glycolytic metabolism and increased export of protective metabolites. Glycerol, in particular, accumulated in the communal metabolic environment and extended the lifespan of all cells in the community in a paracrine fashion. Our results hence establish metabolite exchange interactions as a determinant of the ageing process and show that metabolically cooperating cells shape their metabolic environment to achieve lifespan extension.

biochemistry↗

bioRxiv2019

Combinatorial proteomics and transcriptomics identify AMPK in the control of the axonal regeneration programme of DRG sensory neurons after spinal injury

Regeneration after injury occurs in axons that lie in the peripheral nervous system but it fails in the central nervous system limiting functional recovery. Despite recent progress, the signalling response to injury of peripheral versus central projecting axons that might underpin this differential regenerative ability is currently largely uncharacterized. To fill this knowledge gap, here we combined axoplasmic proteomics from peripheral sciatic or central projecting dorsal root axons from sciatic DRG neurons. Proteomics was combined with cell body RNAseq to compare axonal and soma responses between a spinal regeneration-incompetent versus sciatic regeneration-competent nerve injury. This allowed the identification of injury-dependent signalling pathways uniquely represented in peripheral versus central projecting sciatic DRG axons. RNAseq and proteomics analysis suggested AMPK as a putative regulator of axonal regenerative signalling pathways. AMPK immunoprecipitation followed by mass spectrometry from DRG suggested that the 26S proteasome and its regulatory subunit PSMC5 preferentially interact with AMPK for proteasomal degradation following sciatic axotomy. Mechanistically, we found that the proteasome and CaMKII-dependent proteasomal subunit PSMC5 regulates AMPK1 protein expression. Finally, conditional deletion of AMPK1 promoted multiple regenerative signalling pathways and robust axonal growth across the injured spinal cord, suggesting inhibition of AMPK as a novel regenerative target following spinal injury.\n\nHIGHLIGHTSO_LIAxoplasmic proteomics from sciatic or centrally projecting branches of sciatic DRG identifies unique protein enrichment and signalling pathways, including prior and subsequent to a spinal regeneration-incompetent versus sciatic regeneration-competent axonal injury\nC_LIO_LICombined axoplasmic DRG proteomics and cell body RNAseq analysis suggest AMPK as a central regulator controlling axonal regeneration\nC_LIO_LIThe 26S proteasome and the 19S regulatory subunit PSMC5 interact with AMPK following sciatic axotomy. PSMC5 regulates AMPK1 protein levels\nC_LIO_LIAMPK1 conditional deletion enhances robust axonal growth following SCI\nC_LI

neuroscience↗