{"id":4629,"date":"2025-06-30T01:15:05","date_gmt":"2025-06-30T06:15:05","guid":{"rendered":"https:\/\/www.bocsci.com\/blog\/?p=4629"},"modified":"2025-06-30T01:15:06","modified_gmt":"2025-06-30T06:15:06","slug":"overview-expanding-the-landscape-of-targeted-protein-degradation-tpd","status":"publish","type":"post","link":"https:\/\/www.bocsci.com\/blog\/overview-expanding-the-landscape-of-targeted-protein-degradation-tpd\/","title":{"rendered":"Overview: Expanding the Landscape of Targeted Protein Degradation (TPD)<\/strong>"},"content":{"rendered":"\n

Proteolysis-targeting chimeras (PROTACs)<\/a> and molecular glues<\/a> have pioneered the targeted protein degradation (TPD) field and entered clinical evaluation. These small molecules utilize the ubiquitin-proteasome system to mediate intracellular protein degradation. In recent years, a new class of bifunctional degraders-including LYTACs, AbTACs, PROTABs, KineTACs, REULR, and Trim-Away-has expanded TPD strategies to target membrane and extracellular proteins, unlocking new therapeutic possibilities.<\/p>\n\n\n\n

1. <\/strong>LYTACs (Lysosome Targeting Chimeras)<\/a><\/strong><\/h2>\n\n\n\n

Reference: Nature 2020, 584, 291-297<\/p>\n\n\n\n

LYTACs harness endogenous lysosome trafficking pathways via cation-independent mannose-6-phosphate receptors (CI-M6PR). These chimeras are composed of a targeting moiety (e.g., an antibody or small molecule) linked to a mannose-6-phosphate (M6Pn) ligand. By bridging target proteins with CI-M6PR, LYTACs mediate lysosomal degradation of extracellular and membrane proteins.<\/p>\n\n\n\n

While CI-M6PR is widely expressed, other lysosome-shuttling receptors display tissue-specific patterns, offering opportunities for selective tissue targeting and improved therapeutic windows in future LYTAC applications.<\/p>\n\n\n\n

2. ASGPR-LYTAC<\/strong><\/strong><\/h2>\n\n\n\n

Reference: Nat. Chem. Biol. 2021, 17, 937-946<\/p>\n\n\n\n

ASGPR-LYTACs leverage the liver-specific asialoglycoprotein receptor (ASGPR) to selectively degrade extracellular proteins in hepatocytes. These LYTACs utilize GalNAc or galactose ligands that bind ASGPR and undergo clathrin-mediated endocytosis. Upon endosomal acidification, ASGPR recycles while the ligand-bound protein is trafficked to the lysosome for degradation-enabling cell-type-specific TPD.<\/p>\n\n\n\n

3. KineTACs (Cytokine Receptor-Targeting Chimeras)<\/strong><\/strong><\/h2>\n\n\n\n

Reference: Nat. Biotechnol. 2023, 41, 273-281<\/p>\n\n\n\n

KineTACs are fully genetically encoded bifunctional antibodies that couple a cytokine-binding arm with a target-binding arm. For example, KineTACs incorporating CXCL12 can exploit the decoy receptor CXCR7 to deliver diverse protein targets to lysosomes. Other examples involve CXCL11, vMIPII, or IL-2 for targeting respective cytokine receptors. This modular and versatile platform enables lysosomal degradation of membrane and extracellular proteins, with both broad and tissue-specific applications.<\/p>\n\n\n\n

4. <\/strong>AbTACs (Antibody-Based TPD)<\/a><\/strong><\/h2>\n\n\n\n

Reference: J. Am. Chem. Soc. 2021, 143, 593\u2013598<\/p>\n\n\n\n

AbTACs are bispecific recombinant antibodies designed to degrade membrane proteins via recruitment of membrane-bound E3 ligases. For instance, AbTACs targeting RNF43-a membrane-anchored E3 ligase-can mediate lysosomal degradation of PD-L1. This approach introduces an antibody-based molecular architecture for selective degradation of surface proteins, expanding the capabilities of TPD beyond small molecules.<\/p>\n\n\n\n

5. PROTABs (Protein-Targeting Antibodies for Degradation)<\/strong><\/strong><\/h2>\n\n\n\n

Reference: Nature 2022, 610, 182-189<\/p>\n\n\n\n

PROTABs induce degradation by tethering transmembrane E3 ligases to membrane protein targets. Using ZNRF3, a Wnt-related E3 ligase, PROTABs demonstrated potent and specific degradation of colorectal cancer targets both in vitro and in vivo. This antibody-driven strategy opens a new path for therapeutic degradation of membrane proteins with disease specificity.<\/p>\n\n\n\n

6. REULR (Receptor Elimination by Ubiquitin Ligase Recruitment)<\/strong><\/strong><\/h2>\n\n\n\n

Reference: ACS Synth. Biol. 2023, 12, 1081-1093<\/p>\n\n\n\n

REULRs are nanobody-based bifunctional tools that promote membrane receptor degradation via proximity-induced recruitment of transmembrane E3 ligases (e.g., RNF43, ZNRF3). They effectively eliminate disease-related receptors such as EGFR, EPOR, and PD-1. Additionally, \u201cfratricide\u201d REULRs have been designed to self-degrade surface E3 ligases-offering precise modulation of receptor signaling intensities in various cell types.<\/p>\n\n\n\n

7. Trim-Away<\/strong><\/strong><\/h2>\n\n\n\n

Reference: Cell 2017, 171(7), 1692\u22121706<\/p>\n\n\n\n

Trim-Away enables rapid degradation of endogenous proteins without genetic modification. This method uses antibodies to bind the target protein and TRIM21, an E3 ubiquitin ligase, to trigger proteasomal degradation. Trim-Away is ideal for primary or non-dividing cells, providing immediate effects without long-term compensation seen with RNAi or gene knockouts. It is particularly useful for studying protein function and cell signaling in hard-to-transfect systems.<\/p>\n","protected":false},"excerpt":{"rendered":"

Proteolysis-targeting chimeras (PROTACs) and molecular glues have pioneered the targeted protein degradation (TPD) field and entered clinical evaluation. These small molecules utilize the ubiquitin-proteasome system to mediate intracellular protein degradation. In recent […]<\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"closed","ping_status":"open","sticky":false,"template":"","format":"standard","meta":[],"categories":[882],"tags":[],"_links":{"self":[{"href":"https:\/\/www.bocsci.com\/blog\/wp-json\/wp\/v2\/posts\/4629"}],"collection":[{"href":"https:\/\/www.bocsci.com\/blog\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/www.bocsci.com\/blog\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/www.bocsci.com\/blog\/wp-json\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/www.bocsci.com\/blog\/wp-json\/wp\/v2\/comments?post=4629"}],"version-history":[{"count":1,"href":"https:\/\/www.bocsci.com\/blog\/wp-json\/wp\/v2\/posts\/4629\/revisions"}],"predecessor-version":[{"id":4632,"href":"https:\/\/www.bocsci.com\/blog\/wp-json\/wp\/v2\/posts\/4629\/revisions\/4632"}],"wp:attachment":[{"href":"https:\/\/www.bocsci.com\/blog\/wp-json\/wp\/v2\/media?parent=4629"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.bocsci.com\/blog\/wp-json\/wp\/v2\/categories?post=4629"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.bocsci.com\/blog\/wp-json\/wp\/v2\/tags?post=4629"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}