SENP3 regulates the global protein turnover and the Sp1 level via antagonizing SUMO2/3-targeted ubiquitination and degradation

Abstract

SUMOylation is recently found to function as a targeting signal for the degradation of substrates through the ubiquitin-proteasome system. RNF4 is the most studied human SUMO-targeted ubiquitin E3 ligase. However, the relationship between SUMO proteases, SENPs, and RNF4 remains obscure. There are limited examples of the SENP regulation of SUMO2/3-targeted proteolysis mediated by RNF4. The present study investigated the role of SENP3 in the global protein turnover related to SUMO2/3-targeted ubiquitination and focused in particular on the SENP3 regulation of the stability of Sp1. Our data demonstrated that SENP3 impaired the global ubiquitination profile and promoted the accumulation of many proteins. Sp1, a cancer-associated transcription factor, was among these proteins. SENP3 increased the level of Sp1 protein via antagonizing the SUMO2/3-targeted ubiquitination and the consequent proteasome-dependent degradation that was mediated by RNF4. De-conjugation of SUMO2/3 by SENP3 attenuated the interaction of Sp1 with RNF4. In gastric cancer cell lines and specimens derived from patients and nude mice, the level of Sp1 was generally increased in parallel to the level of SENP3. These results provided a new explanation for the enrichment of the Sp1 protein in various cancers, and revealed a regulation of SUMO2/3 conjugated proteins whose levels may be tightly controlled by SENP3 and RNF4.

Sumoylation-deficient Prdx6 repairs aberrant Sumoylation-mediated Sp1 dysregulation-dependent Prdx6 repression and cell injury in aging and oxidative stress

“…9 ). Posttranslational modification of Sp1 has been shown to influence its transcription activity and stability [ 12 , 25 , 26 , 34 , 35 ]. Glycosylation of Sp1 can stimulate or repress DNA binding and transcription [ 89 ].…”

“…Sumos play important roles in the regulation of diverse cellular processes, including gene transcription, protein stabilization, and subcellular localization [ 12 , 33 – 35 ]. Most, if not all, Sumo modification of transcription factors results in repression of their activity.…”

Regulation of transcription factors by sumoylation

“…Evidence for widespread dependence of ubiquitination on prior sumoylation was provided in a recent study in which overexpression of SUMO3 in HEK293T cells resulted in increased global levels of protein ubiquitination, while overexpression of the SUMO protease SENP3 had the opposite effect. 51 Much of this is likely due to the activity of STUbLs, which recognize specific sumoylated targets and mark them with ubiquitin chains for degradation. For example, PEA3, a TF involved in neuronal pathfinding, and the ubiquitous TFs Sp1 and c-Myc are recognized in their sumoylated form by the STUbL RNF4 which promotes their ubiquitination and degradation.…”

“…For example, PEA3, a TF involved in neuronal pathfinding, and the ubiquitous TFs Sp1 and c-Myc are recognized in their sumoylated form by the STUbL RNF4 which promotes their ubiquitination and degradation. 52-54 Despite the correlation between global levels of sumoylation and ubiquitination, in many cases, sumoylation acts to increase target protein stability by inhibiting ubiquitination. This was first observed with IκBα, the inhibitor of the TF NF-κB, for which sumoylation antagonizes its ubiquitination, leaving it resistant to degradation.…”

SUMO-specific protease 3 is a key regulator for hepatic lipid metabolism in non-alcoholic fatty liver disease

“…The sequences of SENP3-siRNA oligonucleotides were 5′- GGGCUGGAAAGGUUACUUCdTdT-3′ and 3′-dTdTCCCGACCUUUCCAAUGAAG-5′. GFP-SENP3 plasmid and PCDNA3.1 (vehicle plasmid) were kind gifts from the Education Ministry Key Laboratory for Cell Differentiation and Apoptosis, Shanghai Jiaotong University School of Medicine, China1319. These hepatocytes were transfected with the siRNA oligonucleotides or plasmids using lipofectamine 2000 (Invitrogen, USA), according to the manufacturer’s instructions.…”