Quantitative analysis of changes in ubiquitination, protein synthesis and decay caused by protein folding stress due to inhibition of Hsp90

摘要

↑ Hsp70-, Hsp90-, Hsp40 families, ER foldases, ER-Golgi trafficking proteins, proteasome,... Hsp90 itself increases to compensate for its inhibition by GA Hsp90, Hsp70 and associated factors are increasingly synthesized but at later time points their ubiquitination and their decay rates increase significantly. This could be part of an active mechanism aiming at recovery of the normal cellular proteostasis. ↓Hsp90 clients, cell cycle prots, ribosomal proteins, transcription machinery,... Strong, early changes in ubiquitination for Hsp90 clients correlate well with their change in decay rates Kd. Changes of individual proteins follow complex behaviors as function of time: for ex. Cdk6 is depleted then shows signs of a recovery. Co-translational, Ub-mediated degradation has an impact on apparent synthesis measured by pcSILAC. The effect is stronger at early time points. Some Hsp90 clients are depleted by reduced synthesis or destabilization of the folding intermediates (FASN). Other Hsp90 clients are destabilized in general and more ubiquitinated (Cdk6,Lck,Cdk1). Presumably these proteins are constitutively dependent on Hsp90 for stability.