Regulated degradation of the inner nuclear membrane protein SUN2 maintains nuclear envelope architecture and function

Abstract
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Abstract

Nuclear architecture and functions depend on dynamic interactions between nuclear components (such as chromatin) and inner nuclear membrane (INM) proteins. Mutations in INM proteins interfering with these interactions result in disease. However, mechanisms controlling the levels and turnover of INM proteins remain unknown. Here, we describe a mechanism of regulated degradation of the INM SUN domain-containing protein 2 (SUN2). We show that Casein Kinase II and the C-terminal domain Nuclear Envelope Phosphatase 1 (CTDNEP1) have opposing effects on SUN2 levels by regulating SUN2 binding to the ubiquitin ligase Skp/Cullin1/F-Box^βTrCP(SCF^βTrCP). Upon binding to phosphorylated SUN2, SCF^βTrCP promotes its ubiquitination. Ubiquitinated SUN2 is membrane extracted by the AAA ATPase p97 and delivered to the proteasome for degradation. Importantly, accumulation of non-degradable SUN2 results in aberrant nuclear architecture, vulnerability to DNA damage and increased lagging chromosomes in mitosis. These findings uncover a central role of proteolysis in INM protein homeostasis.

Data availability

Sequencing data has been deposited European Nucleotide Archive repository and has the accession number PRJEB54102.

The following data sets were generated

(2022) Genome-wide CRISPR-Cas9 screen (TKOv3) data on SUN2 degradation
ENA, PRJEB54102.

https://www.ebi.ac.uk/ena/browser/view/PRJEB54102

Article and author information

Author details

Logesvaran Krshnan

Sir William Dunn School of Pathology, University of Oxford, Oxford, United Kingdom

Competing interests
The authors declare that no competing interests exist.

"This ORCID iD identifies the author of this article:" 0000-0001-6281-1587
Wingyan Skyla Siu

Sir William Dunn School of Pathology, University of Oxford, Oxford, United Kingdom

Competing interests
The authors declare that no competing interests exist.
Michael Van de Weijer

Sir William Dunn School of Pathology, University of Oxford, Oxford, United Kingdom

Competing interests
The authors declare that no competing interests exist.

"This ORCID iD identifies the author of this article:" 0000-0002-0954-0228
Daniel Hayward

Sir William Dunn School of Pathology, University of Oxford, Oxford, United Kingdom

Competing interests
The authors declare that no competing interests exist.
Elena Navarro Guerrero

Nuffield Department of Medicine, University of Oxford, Oxford, United Kingdom

Competing interests
The authors declare that no competing interests exist.
Ulrike Gruneberg

Sir William Dunn School of Pathology, University of Oxford, Oxford, United Kingdom

Competing interests
The authors declare that no competing interests exist.
Pedro Carvalho

Sir William Dunn School of Pathology, University of Oxford, Oxford, United Kingdom

For correspondence
pedro.carvalho@path.ox.ac.uk

Competing interests
The authors declare that no competing interests exist.

"This ORCID iD identifies the author of this article:" 0000-0002-9691-5277

Funding

European Research Council (817708)

Pedro Carvalho

Wellcome Trust (223153/Z/21/Z)

Pedro Carvalho

Cancer Research UK Discovery Programme (DRCNPG-Nov21\100004)

Ulrike Gruneberg

Medical Research Council (MR/K006703/1)

Ulrike Gruneberg

Edward Penley Abraham Fund (RF 280)

Ulrike Gruneberg

The funders had no role in study design, data collection and interpretation, or the decision to submit the work for publication.

Copyright

This article is distributed under the terms of the Creative Commons Attribution License permitting unrestricted use and redistribution provided that the original author and source are credited.