TRIM65 Inhibitors

Chemical inhibitors of TRIM65 can modulate the protein's activity by interfering with the ubiquitin-proteasome system, which is central to protein degradation. Compounds such as MG132, Lactacystin, Epoxomicin, Bortezomib, Oprozomib, Carfilzomib, Marizomib, and Withaferin A all target the proteasome's function. These inhibitors work by binding to the proteasome and stalling its protein breakdown capabilities. Since TRIM65 functions as an E3 ubiquitin ligase, marking proteins for degradation, the inhibition of the proteasome leads to an accumulation of proteins that TRIM65 has tagged with ubiquitin. This accumulation occurs because the tagged proteins can no longer be broken down by the compromised proteasome. For instance, MG132 does this by reversibly binding to the proteasome's catalytic site, while Lactacystin forms an irreversible bond, both leading to similar outcomes regarding TRIM65's activity. On another front, MLN4924 takes a different approach by inhibiting the NEDD8 activating enzyme. Since the activity of TRIM65 relies on the neddylation process, which is crucial for the functioning of E3 ubiquitin ligases, MLN4924's action prevents TRIM65 from attaching ubiquitin molecules to its substrates. This directly disrupts the ubiquitination process. In contrast, Chloroquine and Concanamycin A intervene in a different degradation pathway-lysosomal. Chloroquine raises the pH within lysosomes, which can impede the degradation of proteins that TRIM65 targets for destruction via this route. Similarly, Concanamycin A, a specific inhibitor of V-ATPases, halts the acidification of lysosomes, which is essential for their protein degrading activity. Although TRIM65 is primarily associated with proteasomal degradation, its interplay with lysosomal pathways can also be significant.