Nucleic Acid-driven Protein Degradation: Frontiers of Lysosomal Targeted Degradation Technology*

Distinct from the complementary inhibition mechanism through binding to the target with threedimensional conformation of small molecule inhibitors, targeted protein degradation technology takes tremendous advantage of endogenous protein degradation pathway inside cells to degrade plenty of "undruggable" target proteins, which provides a novel route for the treatment of many serious diseases, mainly including proteolysis- targeting chimeras, lysosome-targeting chimeras, autophagy-targeting chimeras, antibody-based proteolysis- targeting chimeras, etc. Unlike proteolysis-targeting chimeras first found in 2001, which rely on ubiquitinproteasome system to mainly degrade intracellular proteins of interest, lysosome-targeting chimeras identified in 2020, which was act as the fastly developing technology, utilize cellular lysosomal pathway through endocytosis mediated by lysosome-targeting receptor to degrade both extracellular and membrane proteins. As an emerging biomedical technology, nucleic acid-driven lysosome-targeting chimeras utilize nucleic acids as certain components of chimera molecule to replace with ligand to lysosome-targeting receptor or protein of interest, exhibiting broad application prospects and potential clinical value in disease treatment and drug development. This review mainly introduced present progress of nucleic acid-driven lysosome-targeting chimeras technology, including its basic composition, its advantages compared with antibody or glycopeptide-based lysosome-targeting chimeras, and focused on its chief application, in terms of the type of lysosome-targeting receptors. Most research about the development of nucleic acid-driven lysosome-targeting chimeras focused on those which utilized cation- independent mannose-6-phosphonate receptor as the lysosome-targeting receptor. Both mannose-6-phosphonatemodified glycopeptide and nucleic aptamer targeting cation-independent mannose-6-phosphonate receptor, even double-stranded DNA molecule moiety can be taken advantage as the ligand to lysosome-targeting receptor. The same as classical lysosome-targeting chimeras, asialoglycoprotein receptor can also be used for advance of nucleic acid-driven lysosome-targeting chimeras. Another new-found lysosome-targeting receptor, scavenger receptor, can bind dendritic DNA molecules to mediate cellular internalization of complex and lysosomal degradation of target protein, suggesting the successful application of scavenger receptor-mediated nucleic acid- driven lysosome-targeting chimeras. In addition, this review briefly overviewed the history of lysosome-targeting chimeras, including first-generation and second-generation lysosome-targeting chimeras through cation- independent mannose-6-phosphonate receptor-mediated and asialoglycoprotein receptor-mediated endocytosis respectively, so that a clear timeline can be presented for the advance of chimera technique. Meantime, current deficiency and challenge of lysosome-targeting chimeras was also mentioned to give some direction for deep progress of lysosome-targeting chimeras. Finally, according to faulty lysosomal degradation efficiency, more cellular mechanism where lysosome-targeting chimeras perform degradation of protein of interest need to be deeply explored. In view of current progress and direction of nucleic acid-driven lysosome-targeting chimeras, we discussed its current challenges and development direction in the future. Stability of natural nucleic acid molecule and optimized chimera construction have a great influence on the biological function of lysosome-targeting chimeras. Discovery of novel lysosome-targeting receptors and nucleic aptamer with higher affinity to the target will greatly facilitate profound advance of chimera technique. In summary, nucleic acid-driven lysosome-targeting chimeras have many superiorities, such as lower immunogenicity, expedient synthesis of chimera molecules and so on, in contrast to classical lysosome-targeting chimeras, making it more valuable. Also, the chimera technology provides new ideas and methods for biomedical research, drug development and clinical treatment, and can be used more widely through further research and optimization.