CRISPR/Cas9 genome-wide screens using sterol-sensitive endogenous HMG-CoA reductase (HMGCR) reporter identify the sterol-responsive RNF145 and gp78 as independently responsible for sterol-accelerated degradation of HMGCR, the rate-limiting enzyme of cholesterol biosynthesis.
A deubiquitinase antagonizes the activity of an associated E3 ligase to prevent uncontrolled ubiquitination of a degradation machinery protein and thus maintain its functionality in protein quality control at the endoplasmic reticulum.
Client protein-driven reversal of endoplasmic reticulum chaperone (BiP) mediated-repression is revealed as a principal component of the regulation of the unfolded protein response transducer IRE1 in cells.
Proinsulin misfolding, an established cause of diabetes in patients with INS gene mutations, is now observed in normal human pancreatic islets, and rodents with genetic predisposition to type 2 diabetes.
The extent of (proteotoxic) endoplasmic reticulum stress, and the ensuing unfolded protein response activation, are commensurate with the extent of the chaperone BiP being sequestered by its client proteins.