The effects of ethionamide on cereblon stability and its potential role in alleviating neurodegenerative symptoms

Abstract

Cereblon (CRBN) was initially identified through genetic studies related to mild intellectual disability and has since been studied as a major target of thalidomide-induced teratogenicity. Subsequent research revealed that CRBN functions as a substrate receptor within the Cullin-4-RING E3 ubiquitin ligase complex (CRL4CRBN), where it recognizes specific endogenous substrates and promotes their ubiquitination and degradation. Previous studies have identified DNAJA1 (DJ2) and DNAJB1 (DJ1), members of the DNAJ protein family, as novel endogenous substrates of CRBN. These proteins serve as co-chaperones that help to suppress the aggregation of Tau and α-Synuclein, pathological proteins closely associated with Alzheimer’s disease (AD) and Parkinson’s disease (PD), respectively. Accordingly, preventing the degradation of DJ1 and DJ2 has been suggested as a potential strategy to reduce pathological protein accumulation and to slow the progression of neurodegenerative diseases. The objective of this study was to identify small-molecule compounds capable of modulating the protein levels of DNAJ family members, specifically DJ1 and DJ2, which are regulated by CRBN. To this end, an ELISA-based screening assay was employed to identify candidate compounds that interfere with the CRBN–DNAJ interaction. Among the identified candidates, ethionamide (Eth) was selected for further investigation based on validation through co-immunoprecipitation (Co-IP) and additional cell-based assays. The effects of Eth on CRBN and DNAJ protein levels were subsequently evaluated using cycloheximide (CHX) chase assays and time-dependent analyses, which indicated that Eth treatment was associated with a decrease in CRBN protein levels. Furthermore, in vivo experiments were conducted to assess whether the effects observed in cell-based systems were recapitulated in animal models. The results demonstrated that Eth treatment in a PD mouse model led to improved motor performance and a significant reduction in CRBN protein levels in brain tissue. These findings suggest that Eth may modulate CRBN stability and could serve as a potential therapeutic candidate for neurodegenerative disorders.