Degradation of lipid droplets by chimeric autophagy-tethering compounds

Abstract

Degrading pathogenic proteins by degrader technologies such as PROTACs (proteolysis-targeting chimeras) provides promising therapeutic strategies, but selective degradation of non-protein pathogenic biomolecules has been challenging. Here, we demonstrate a novel strategy to degrade non-protein biomolecules by autophagy-tethering compounds (ATTECs), using lipid droplets (LDs) as an exemplar target. LDs are ubiquitous cellular structures storing lipids and could be degraded by autophagy. We hypothesized that compounds interacting with both the LDs and the key autophagosome protein LC3 may enhance autophagic degradation of LDs. We designed and synthesized such compounds by connecting LC3-binding molecules to LD-binding probes via a linker. These compounds were capable of clearing LDs almost completely and rescued LD-related phenotypes in cells and in two independent mouse models with hepatic lipidosis. We further confirmed that the mechanism of action of these compounds was mediated through LC3 and autophagic degradation. Our proof-of-concept study demonstrates the capability of degrading LDs by ATTECs. Conceptually, this strategy could be applied to other protein and non-protein targets.

The AUTOTAC chemical biology platform for targeted protein degradation via the autophagy-lysosome system

“…Moreover, Ub-dependent PROTAC may not be an ideal TPD platform to degrade misfolded and aggregation-prone pathological protein species, such as those of neurodegenerative proteinopathies, as these protein species are typically resistant to unfolding and subsequent degradation by the proteasome due to size limitations 12,13 . Recent advances in the field of autophagy-based degraders or molecular glues, such as AUTAC, ATTEC, and LYTAC have been successful in degrading a number of targets via the lysosome [14][15][16][17] . However, LYTAC is applicable to only extracellular proteins, ATTEC directly targets mutant Htt or lipid droplets to the autophagosome without prior sequestration, and AUTAC utilizes S-guanylation that is still dependent on ubiquitination of the target [14][15][16][17] .…”

“…Recent advances in the field of autophagy-based degraders or molecular glues, such as AUTAC, ATTEC, and LYTAC have been successful in degrading a number of targets via the lysosome [14][15][16][17] . However, LYTAC is applicable to only extracellular proteins, ATTEC directly targets mutant Htt or lipid droplets to the autophagosome without prior sequestration, and AUTAC utilizes S-guanylation that is still dependent on ubiquitination of the target [14][15][16][17] . These challenges of the existing TPD modalities necessitate further development of a generally applicable TPD platform independent of Ub and the proteasome.…”

Alterations in the Plasma Lipidome of Adult Women With Bipolar Disorder: A Mass Spectrometry-Based Lipidomics Research

“…Experiments and data analysis were performed as previously described ( 33 , 34 ) and were supported by Shanghai Applied Protein Technology Co., Ltd. For the sample preparation, plasma (100 μl) was accurately measured and spiked with appropriate amounts of internal lipid standards (SPLASH ® LIPIDOMIX ® Mass Spec Standard, methanol solution, AVANTI, 330707-1EA, Merck) and homogenized with 200 μl water and 240 μl methanol. Thereafter, 800 μl methyl tert-butyl ether was added, and the samples were subjected to ultrasonication for 20 min at 4°C and allowed to rest for 30 min at room temperature.…”

The Emerging Roles of Autophagy in Human Diseases

“…For instance, a recent study designed autophagy-tethering compounds targeting lipid droplets to induce their degradation. Treating mice with these compounds leads to a lower body weight [ 413 ], which indicates a role of lipophagy in obesity. However, the mechanism and the treatment potential of modulating lipophagy need further study.…”