Inhibiting ubiquitination causes an accumulation of SUMOylated newly synthesized nuclear proteins at PML bodies.

Content Provider	Europe PMC
Author	Sha, Zhe Blyszcz, Tamara González-Prieto, Román Vertegaal, Alfred C. O. Goldberg, Alfred L.
Copyright Year	2019
Abstract	Protein ubiquitination and SUMOylation are required for the maintenance of cellular protein homeostasis, and both increase in proteotoxic conditions (e.g. heat shock or proteasome inhibition). However, we found that when ubiquitination was blocked in several human cell lines by inhibiting the ubiquitin-activating enzyme with TAK243, there was an unexpected, large accumulation of proteins modified by SUMO2/3 chains or SUMO1, but not by several other ubiquitin-like proteins. This buildup of SUMOylated proteins was evident within 3–4 h. It required the small ubiquitin-like modifier (SUMO)-conjugating enzyme, UBC9, and the promyelocytic leukemia protein (PML) and thus was not due to nonspecific SUMO conjugation by ubiquitination enzymes. The SUMOylated proteins accumulated predominantly bound to chromatin and were localized to PML nuclear bodies. Because blocking protein synthesis with cycloheximide prevented the buildup of SUMOylated proteins, they appeared to be newly-synthesized proteins. The proteins SUMOylated after inhibition of ubiquitination were purified and analyzed by MS. In HeLa and U2OS cells, there was a cycloheximide-sensitive increase in a similar set of SUMOylated proteins (including transcription factors and proteins involved in DNA damage repair). Surprisingly, the inhibition of ubiquitination also caused a cycloheximide-sensitive decrease in a distinct set of SUMOylated proteins (including proteins for chromosome modification and mRNA splicing). More than 80% of the SUMOylated proteins whose levels rose or fell upon inhibiting ubiquitination inhibition underwent similar cycloheximide-sensitive increases or decreases upon proteasome inhibition. Thus, when nuclear substrates of the ubiquitin–proteasome pathway are not efficiently degraded, many become SUMO-modified and accumulate in PML bodies.
ISSN	00219258
Volume Number	294
PubMed Central reference number	PMC6802522
Issue Number	42
PubMed reference number	31285264
Journal	The Journal of Biological Chemistry [J. Biol. Chem]
e-ISSN	1083351X
DOI	10.1074/jbc.RA119.009147
Language	English
Publisher	American Society for Biochemistry and Molecular Biology
Publisher Date	2019-07-08
Publisher Place	U.S.A.
Access Restriction	Open
Rights License	Author's Choice—Final version open access under the terms of the Creative Commons CC-BY license. © 2019 Sha et al.
Subject Keyword	ubiquitin proteasome ubiquitylation (ubiquitination) small ubiquitin-like modifier (SUMO) sumoylation nuclear body promyelocytic leukemia (PML) SUMO-conjugating enzyme UBC9 TAK243 ubiquitin-activating enzyme (UAE/E1))
Content Type	Text
Resource Type	Article
Subject	Cell Biology Molecular Biology Biochemistry