8vw4
Crystal structure of Cbl-b TKB bound to compound 26
Structural highlights
FunctionCBLB_HUMAN E3 ubiquitin-protein ligase which accepts ubiquitin from specific E2 ubiquitin-conjugating enzymes, and transfers it to substrates, generally promoting their degradation by the proteasome. Negatively regulates TCR (T-cell receptor), BCR (B-cell receptor) and FCER1 (high affinity immunoglobulin epsilon receptor) signal transduction pathways. In naive T-cells, inhibits VAV1 activation upon TCR engagement and imposes a requirement for CD28 costimulation for proliferation and IL-2 production. Also acts by promoting PIK3R1/p85 ubiquitination, which impairs its recruitment to the TCR and subsequent activation. In activated T-cells, inhibits PLCG1 activation and calcium mobilization upon restimulation and promotes anergy. In B-cells, acts by ubiquitinating SYK and promoting its proteasomal degradation. May also be involved in EGFR ubiquitination and internalization.[1] [2] [3] [4] Publication Abstract from PubMedWe were attracted to the therapeutic potential of inhibiting Casitas B-lineage lymphoma proto-oncogene-b (Cbl-b), a RING E3 ligase that plays a critical role in regulating the activation of T cells. However, given that only protein-protein interactions were involved, it was unclear whether inhibition by a small molecule would be a viable approach. After screening an approximately 6 billion member DNA-encoded library (DEL) using activated Cbl-b, we identified compound 1 as a hit for which the cis-isomer (2) was confirmed by biochemical and surface plasmon resonance (SPR) assays. Our hit optimization effort was greatly accelerated when we obtained a cocrystal structure of 2 with Cbl-b, which demonstrated induced binding at the substrate binding site, namely, the Src homology-2 (SH2) domain. This was quite noteworthy given that there are few reports of small molecule inhibitors that bind to SH2 domains and block protein-protein interactions. Structure- and property-guided optimization led to compound 27, which demonstrated measurable cell activity, albeit only at high concentrations. Optimization of a Novel DEL Hit That Binds in the Cbl-b SH2 Domain and Blocks Substrate Binding.,Liang J, Lambrecht MJ, Arenzana TL, Aubert-Nicol S, Bao L, Broccatelli F, Cai J, Eidenschenk C, Everett C, Garner T, Gruber F, Haghshenas P, Huestis MP, Hsu PL, Kou P, Jakalian A, Larouche-Gauthier R, Leclerc JP, Leung DH, Martin A, Murray J, Prangley M, Rutz S, Kakiuchi-Kiyota S, Satz AL, Skelton NJ, Steffek M, Stoffler D, Sudhamsu J, Tan S, Wang J, Wang S, Wang Q, Wendorff TJ, Wichert M, Yadav A, Yu C, Wang X ACS Med Chem Lett. 2024 May 29;15(6):864-872. doi: , 10.1021/acsmedchemlett.4c00068. eCollection 2024 Jun 13. PMID:38894924[5] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. References
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