Hes-1 SUMOylation by protein inhibitor of activated STAT1 enhances the suppressing effect of Hes-1 on GADD45α expression to increase cell survival

Abstract

BackgroundHairy and Enhancer of split 1 (Hes-1) is a transcriptional repressor that plays an important role in neuronal differentiation and development, but post-translational modifications of Hes-1 are much less known. In the present study, we aimed to investigate whether Hes-1 could be SUMO-modified and identify the candidate SUMO acceptors on Hes-1. We also wished to examine the role of the SUMO E3 ligase protein inhibitor of activated STAT1 (PIAS1) in SUMOylation of Hes-1 and the molecular mechanism of Hes-1 SUMOylation. Further, we aimed to identify the molecular target of Hes-1 and examine how Hes-1 SUMOylation affects its molecular target to affect cell survival.ResultsIn this study, by using HEK293T cells, we have found that Hes-1 could be SUMO-modified and Hes-1 SUMOylation was greatly enhanced by the SUMO E3 ligase PIAS1 at Lys8, Lys27 and Lys39. Furthermore, Hes-1 SUMOylation stabilized the Hes-1 protein and increased the transcriptional suppressing activity of Hes-1 on growth arrest and DNA damage-inducible protein alpha (GADD45α) expression. Overexpression of GADD45α increased, whereas knockdown of GADD45αα expression decreased cell apoptosis. In addition, H2O2 treatment increased the association between PIAS1 and Hes-1 and enhanced the SUMOylation of Hes-1 for endogenous protection. Overexpression of Hes-1 decreased H2O2-induced cell death, but this effect was blocked by transfection of the Hes-1 triple sumo-mutant (Hes-1 3KR). Overexpression of PIAS1 further facilitated the anti-apoptotic effect of Hes-1. Moreover, Hes-1 SUMOylation was independent of Hes-1 phosphorylation and vice versa.ConclusionsThe present results revealed, for the first time, that Hes-1 could be SUMO-modified by PIAS1 and GADD45α is a novel target of Hes-1. Further, Hes-1 SUMOylation mediates cell survival through enhanced suppression of GADD45α expression. These results revealed a novel role of Hes-1 in addition to its involvement in Notch signaling. They also implicate that SUMOylation could be an important posttranslational modification that regulates cell survival.

Epigenetic regulation of HDAC1 SUMOylation as an endogenous neuroprotection against Aβ toxicity in a mouse model of Alzheimer’s disease

“…Because PIAS1 was suggested to have a protective role against H 2 O 2 -induced cell death 25 and the anti-apoptotic gene Mcl-1 was shown to exert a neuroprotective effect in the brain, 13, 26 we first examined whether acute A β treatment increases the expression of PIAS1 and Mcl-1. Rats were divided to three groups and received 1% NH 4 OH (control group), A β (14  μ g) injection and sacrificed 30 min later, and A β injection (14  μ g) but killed 1 h later.…”

“…These results are consistent with the report that PIAS1 has an anti-apoptotic role. 25 But they are incongruent with the studies showing that PIAS1 is pro-apoptotic. 34, 35 One possible explanation for this discrepancy is that for the study showing an anti-apoptotic role of PIAS1, low concentration of PIAS1 plasmid DNA was transfected to HEK293T cells; however, for the studies showing a pro-apoptotic role of PIAS1, inducible PIAS1 expression was adopted.…”

“…Protein inhibitor of activated STAT1 (PIAS1) is a SUMO E3 ligase that enhances the SUMOylation of a variety of proteins. In addition, PIAS1 was shown to protect against H 2 O 2 -induced cell death, 25 indicating that PIAS1 has an anti-apoptotic role. In the present study we aimed to examine the role and mechanism of HDAC1 SUMOylation by PIAS1 in protecting against A β toxicity by adopting the APPswe/PS1dE9 (APP/PS1) mice as a mouse model for AD.…”

SUMOylation Negatively Regulates Angiogenesis by Targeting Endothelial NOTCH Signaling

“…On the other hand, we also observed that SENP1 mediates HES-1 deSUMOylation in endothelial cells (Online Figure VIII), based on a previous report. 34 N1ICD SUMOylation occurs in the cytosol or on the membrane, while HES-1 SUMOylation may occur in the nucleus; therefore, the synergistic modulation of SENP1 in NOTCH signaling-controlled endothelial growth is worthy of investigation. Moreover, there is little knowledge about the cooperation of SUMOylation with other post-translational modifications, such as ubiquitination and phosphorylation, to manipulate the efficiency of NOTCH signaling.…”

A Novel Post-translational Modification of Nucleolin, SUMOylation at Lys-294, Mediates Arsenite-induced Cell Death by Regulating gadd45α mRNA Stability

“…3G, we anticipated that arsenite might specifically regulate nucleolin SUMO E3 ligase expression or activity rather than affect the global SUMO activation (E1) or conjugation (E2) process. The SUMO E3 ligase, protein inhibitor of activated STAT1 (PIAS1), is reported to mediate the SUMOylation of hairy and enhancer of split 1 (Hes-1), which could transcriptionally regulate GADD45␣ expression as well as proapoptotic function (43). The role of PIAS1 in the regulation of nucleolin SUMOylation is currently under investigation in our laboratory.…”