Ubiquitin-proteasome system and Forkhead box O3 pathway (UPS-FoxO3)

The Ubiquitin-proteasome system (UPS) and FoxO3α (Forkhead box O3) pathway represent a critical regulatory axis responsible for maintaining cellular protein homeostasis and responding to metabolic stress (UniProt, 2024). FoxO3 acts as a transcription factor that, when dephosphorylated and translocated to the nucleus, upregulates the expression of key E3 ubiquitin ligases such as Atrogin-1 (FBXO32) and MuRF1 (TRIM63) (Sandri et al., 2004). These ligases tag specific proteins with ubiquitin, marking them for degradation by the 26S proteasome complex (StatPearls, 2023). This pathway is a primary driver of muscle atrophy in various pathological states, including cancer cachexia, chronic kidney disease, and aging (PubMed, 2021). In the context of oncology, the UPS is often hyperactive, leading to the degradation of pro-apoptotic proteins and tumor suppressors, which promotes cancer cell survival (NIH, 2022). Therapeutic interventions targeting this axis include proteasome inhibitors like Bortezomib, which are used to treat multiple myeloma by inducing proteotoxic stress (PubChem, 2024). Additionally, small molecules targeting FoxO3 or its upstream regulators like Akt are being explored to modulate protein turnover in metabolic and degenerative diseases (Journal of Clinical Investigation, 2020). Understanding the balance of this pathway is essential for developing treatments that can either halt muscle wasting or selectively induce apoptosis in malignant cells.

Other names

FoxO3a-UPS axisFoxO3-Atrogin-1/MuRF1 pathwayUPS-FoxO3 signalingForkhead box O3-mediated proteolysisFoxO3-mediated ubiquitin-proteasome pathway

Inhibition of the 26S proteasome to prevent protein degradation or modulation of FoxO3 transcriptional activity to regulate the expression of E3 ubiquitin ligases.