The orphan nuclear receptor SHP regulates ER stress response by inhibiting XBP1s degradation.

The orphan nuclear receptor SHP (small heterodimer partner) is a well-known transcriptional corepressor of bile acid and lipid metabolism in the liver; however, its function in other tissues is poorly understood. Here, we report an unexpected role for SHP in the exocrine pancreas as a modulator of the endoplasmic reticulum ...
(ER) stress response. SHP expression is induced in acinar cells in response to ER stress and regulates the protein stability of the spliced form of X-box-binding protein 1 (XBP1s), a key mediator of ER stress response. Loss of SHP reduces XBP1s protein level and transcriptional activity, which in turn attenuates the ER stress response during the fasting-feeding cycle. Consequently, SHP-deficient mice also are more susceptible to cerulein-induced pancreatitis. Mechanistically, we show that SHP physically interacts with the transactivation domain of XBP1s, thereby inhibiting the polyubiquitination and degradation of XBP1s by the Cullin3-SPOP (speckle-type POZ protein) E3 ligase complex. Together, our data implicate SHP in governing ER homeostasis and identify a novel posttranslational regulatory mechanism for the key ER stress response effector XBP1.
Mesh Terms:
Acinar Cells, Animals, Endoplasmic Reticulum Stress, Gene Expression Profiling, Gene Expression Regulation, HEK293 Cells, Humans, Mice, Mice, Inbred C57BL, Pancreas, Exocrine, Pancreatitis, Protein Splicing, Protein Stability, Proteolysis, Receptors, Cytoplasmic and Nuclear, Ubiquitination, X-Box Binding Protein 1
Genes Dev.
Date: Dec. 01, 2018
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