Unbiased proteomic screening identifies a novel role for the E3 ubiquitin ligase Nedd4‐2 in translational suppression during ER stress

Endoplasmic reticulum (ER) stress occurs when protein folding or maturation is disrupted. A malfunction in the ER stress response can lead to cell death and has been observed in many neurological diseases. However, how the ER stress response is regulated in neuronal cells remains largely unclear. He...

Full description

Saved in:
Bibliographic Details
Published in:Journal of neurochemistry 2021-06, Vol.157 (6), p.1809-1820
Main Authors: Eagleman, Daphne E., Zhu, Jiuhe, Liu, Dai‐Chi, Seimetz, Joseph, Kalsotra, Auinash, Tsai, Nien‐Pei
Format: Article
Language:English
Subjects:
Cell death
Cellular stress response
Dephosphorylation
Endoplasmic reticulum
Immunoprecipitation
Liquid chromatography
Mass spectrometry
Mass spectroscopy
Membranes
Nedd4‐2
Neurological diseases
Protein folding
Proteins
Regulatory mechanisms (biology)
Ribosomal proteins
ribosome
Ribosomes
Serine
stress
Target recognition
Translation
Ubiquitin
Ubiquitin-protein ligase
Ubiquitination
Western blotting
Citations: Items that this one cites
Items that cite this one
Online Access:Get full text
Tags: Add Tag
No Tags, Be the first to tag this record!
Description
Summary:Endoplasmic reticulum (ER) stress occurs when protein folding or maturation is disrupted. A malfunction in the ER stress response can lead to cell death and has been observed in many neurological diseases. However, how the ER stress response is regulated in neuronal cells remains largely unclear. Here, we studied an E3 ubiquitin ligase named neural precursor cell expressed developmentally down‐regulated protein 4‐like (Nedd4‐2). Nedd4‐2 is highly expressed in the brain and has a high affinity toward ubiquitinating membrane‐bound proteins. We first utilized unbiased proteomic profiling with ultra‐performance liquid chromatography–tandem mass spectrometry (UPLC–MS/MS) of isolated membrane fractions from mouse whole brains to identify novel targets of Nedd4‐2. Through this screen, we found that the expression and ubiquitination of ribosomal proteins are regulated by Nedd4‐2 and we confirmed an association between Nedd4‐2 and ribosomes through ribosome sedimentation and polysome profiling. Further, we utilized immunoprecipitation and western blotting to show that induction of ER stress promotes an association between Nedd4‐2 and ribosomal proteins, which is mediated through dephosphorylation of Nedd4‐2 at serine‐342. This increased interaction between Nedd4‐2 and ribosomal proteins in turn mediates ER stress‐associated translational suppression. In summary, the results of this study demonstrate a novel regulatory mechanism underlying the ER stress response and a novel function of Nedd4‐2 in translational control. Our findings may shed light on neurological diseases in which the ER stress response or the function of Nedd4‐2 is dysregulated. In undisturbed neurons, Nedd4‐2 interacts transiently with ribosomal proteins to mediate basal translation rates. Under conditions in which neurons experience endoplasmic reticulum (ER) stress, Nedd4‐2 becomes dephosphorylated at serine‐342. This dephosphorylation mediates increased affinity toward ribosomal proteins and acts to suppress translation through a ubiquitination independent mechanism. In the absence of this mechanism, as is the case in neurons lacking Nedd4‐2, translational suppression is impaired upon induction of ER stress. These findings uncovered a novel regulatory mechanism by which ER stress elicits translation suppression in neurons and introduced Nedd4‐2 as a novel translational regulator.
ISSN:0022-3042
1471-4159
DOI:10.1111/jnc.15219