Baldensperger, T. | bioRxiv Science

bioRxiv2024

Age pigment lipofuscin causes oxidative stress, lysosomal dysfunction, and pyroptotic cell death

Accumulation of the age pigment lipofuscin represents a ubiquitous hallmark of the aging process. However, our knowledge about cellular effects of lipofuscin accumulation is potentially flawed, because previous research mainly utilized highly artificial methods of lipofuscin generation. In order to address this tremendous problem, we developed a convenient protocol for isolation of authentic lipofuscin from human and equine cardiac tissue in high purity and quantity. Isolated lipofuscin aggregates contained elevated concentrations of proline and metals such as calcium or iron. The material was readily incorporated by fibroblasts and caused cell death at low concentrations (LC50 = 5.0 {micro}g/mL) via a pyroptosis-like pathway. Lipofuscin boosted mitochondrial ROS production and caused lysosomal dysfunction by lysosomal membrane permeabilization leading to reduced lysosome quantity and impaired cathepsin D activity. In conclusion, this is the first study utilizing authentic lipofuscin to experimentally validate the concept of the lysosomal-mitochondrial axis theory of aging and cell death.

cell biology↗

bioRxiv2020

Mapping sites of carboxymethyllysine modification on proteins reveals its consequences for proteostasis and cell proliferation

Posttranslational mechanisms play a key role in modifying the abundance and function of cellular proteins. Among these, modification by advanced glycation end products (AGEs) has been shown to accumulate during aging and age-associated diseases but specific protein targets and functional consequences remain largely unexplored. Here, we devised a proteomic strategy to identify specific sites of carboxymethyllysine (CML) modification, one of the most abundant AGEs. We identified over 1000 sites of CML modification in mouse and primary human cells treated with the glycating agent glyoxal. By using quantitative proteomics, we found that protein glycation triggers a proteotoxic response and directly affects the protein degradation machinery. We show that glyoxal induces cell cycle perturbation in primary endothelial cells and that CML modification reduces acetylation of tubulins and impairs microtubule dynamics. Our data demonstrate the relevance of AGE modification for cellular function and pinpoint specific protein networks that might become compromised during aging. HighlightsO_LIA peptide enrichment strategy allows mapping of CML modification in cells and tissues C_LIO_LICML modification competes with ubiquitination or acetylation of lysines C_LIO_LIGlyoxal treatment destabilizes the 26S proteasome C_LIO_LIGlyoxal arrests cell cycle and impairs microtubule dynamics via altering the tubulin code C_LI

biochemistry↗