Kaufmann, S. V. | Search bioRxiv

bioRxiv2025

Proteo-transcriptomic reprogramming and resource reallocation define the aging mammalian brain

Brain aging is a major risk for neurodegeneration, yet the underlying molecular mechanisms remain poorly understood. Here we performed an integrative proteo-transcriptomic analysis of the aging mouse brain, uncovering molecular signatures of aging through the assessment of protein aggregation, mRNA relocalization, and comparative proteomics across eight models of premature aging and neurodegeneration. We identified dynamic changes in physiological aging highlighting differences in synaptic maintenance and energy-allocation. These were linked to changes associated with fundamental protein biochemical properties such as size and net charge. Network analysis highlighted a decrease in mitochondrial complex I proteins not compensated at the mRNA level. Aggregation of 60S ribosome subunits indicated deteriorating translation efficiency and was accompanied by mitochondrial and proteasomal imbalance. The analysis of the nine models revealed key similarities and differences between physiological aging and pathology. Overall, our study provides an extensive resource on molecular aging, and offers insights into mechanisms predisposing to neurodegeneration, easily accessible at our Brain Aging and Molecular Atlas Project (BrainAging-MAP) website.

neuroscience↗

bioRxiv2024

Calcium-triggered (de)ubiquitination events in synapses

Neuronal communication relies on neurotransmitter release from synaptic vesicles (SVs), whose dynamics are controlled by calcium-dependent pathways, as many thoroughly studied phosphorylation cascades. However, little is known about other post-translational modifications, as ubiquitination. To address this, we analysed resting and stimulated synaptosomes (isolated synapses) by quantitative mass spectrometry. We identified more than 5,000 ubiquitination sites on [~]2,000 proteins, the majority of which participate in SV recycling processes. Several proteins showed significant changes in ubiquitination in response to calcium influx, with the most pronounced changes in CaMKII and the clathrin adaptor protein AP180. To validate this finding, we generated a CaMKII mutant lacking the ubiquitination target site (K291) and analysed it both in neurons and non-neuronal cells. K291 ubiquitination influences CaMKII activity and synaptic function by modulating its autophosphorylation at a functionally important site (T286). We suggest that ubiquitination in response to synaptic activity is an important regulator of synaptic function.

neuroscience↗