Protein Synthesis and Degradation
Diptoindonesin G is a middle domain HSP90 modulator for cancer treatment
HSP90 inhibitors can target many oncoproteins simultaneously, but none have made it through clinical trials due to dose-limiting toxicity and induction of heat shock response, leading to clinical resistance. We identified diptoindonesin G (dip G) as an HSP90 modulator that can promote degradation of HSP90 clients by binding to the middle domain of HSP90 (Kd = 0.13 ± 0.02 μM) without inducing heat shock response. This is likely because dip G does not interfere with the HSP90–HSF1 interaction like N-terminal inhibitors, maintaining HSF1 in a transcriptionally silent state.A STUB1 ubiquitin ligase/CHIC2 protein complex negatively regulates the IL-3, IL-5, and GM-CSF cytokine receptor common β chain (CSF2RB) protein stability
The IL-3, IL-5, and GM-CSF family of cytokines play an essential role in the growth, differentiation, and effector functions of multiple hematopoietic cell types. Receptors in this family are composed of cytokine-specific α chains and a common β chain (CSF2RB), responsible for the majority of downstream signaling. CSF2RB abundance and stability influence the magnitude of the cellular response to cytokine stimulation, but the exact mechanisms of regulation are not well understood. Here, we use genetic screens in multiple cellular contexts and cytokine conditions to identify STUB1, an E3 ubiquitin ligase, and CHIC2 as regulators of CSF2RB ubiquitination and protein stability.Quantitative interactome proteomics identifies a proteostasis network for GABAA receptors
Gamma-aminobutyric acid type A (GABAA) receptors are the primary inhibitory neurotransmitter-gated ion channels in the mammalian central nervous system. Maintenance of GABAA receptor protein homeostasis (proteostasis) in cells utilizing its interacting proteins is essential for the function of GABAA receptors. However, how the proteostasis network orchestrates GABAA receptor biogenesis in the endoplasmic reticulum is not well understood. Here, we employed a proteomics-based approach to systematically identify the interactomes of GABAA receptors.
