The nuclear receptor NR4A1 is regulated by SUMO modification to induce autophagic cell death

Abstract

242 25 Abstract 26 NR4A is a nuclear receptor protein family whose members act as sensors of cellular 27 environment and regulate multiple processes such as metabolism, proliferation, migration, 28 apoptosis, and autophagy. Since the ligand binding domains of these receptors have no 29 cavity for ligand interaction, their function is most likely regulated by protein abundance 30 and post-translational modifications. In particular, NR4A1 is regulated by protein 31 abundance, phosphorylation, and subcellular distribution (nuclear-cytoplasmic 32 translocation), and acts both as a transcription factor and as a regulator of other 33 interacting proteins. SUMOylation is a post-translational modification that can affect protein 34 stability, transcriptional activity, alter protein-protein interactions and modify intracellular 35 localization of target proteins. In the present study we evaluated the role of SUMOylation 36 as a posttranslational modification that can regulate the activity of NR4A1 to induce 37 autophagy-dependent cell death. We focused on a model potentially relevant for neuronal 38 cell death and demonstrated that NR4A1 needs to be SUMOylated to induce autophagic 39 cell death. We observed that a triple mutant in SUMOylation sites has reduced 40 SUMOylation, increased transcriptional activity, altered intracellular distribution, and more 41 importantly, its ability to induce autophagic cell death is impaired. 42 43 Summary Statement 44 The modification of the nuclear receptor NR4A1 by SUMO regulates its transcriptional 45 activity, intracellular localization and is required to induce autophagic cell death.46 47 Short title: SUMOylated NR4A1 induces autosis 48 49 Keywords: 50 NR4A1, SUMO, autophagy, cell death, Substance P, NK 1 R3 51 52 Abbreviations list 53 NR4A Nuclear receptor group family A 54 NR4A1 Nuclear receptor group 4 family A member 1 (Nur77, NGF1B, TR3, etc.) 55 NR4A2 Nuclear receptor group 4 family A member 2 (Nurr1, NOT1, etc) 56 NR4A3 Nuclear receptor group 4 family A member 3 (Nor1, MINOR) 57 SUMO small ubiquitin-like modifier 58 SP Substance P 59 NK 1 R Neurokinin 1 Receptor 60 TAD Trans-Activation Domain 61 DBD DNA Binding Domain 62 LBD Ligand Binding Domain 63 PTM Post Translational Modifications 4 64 Introduction 65 Nuclear receptors are a superfamily of transcription factors involved in a vast number of 66 biological processes. They share three common structural domains: a N-terminal 67 transactivation domain (TAD), a central double zinc finger DNA binding domain (DBD) and 68 a C-terminal ligand binding domain (LBD). Among the known human nuclear receptors, 69 the ones belonging to the NR4A family act as sensors of the cellular environment and 70 contribute to cell fate decisions, such as cell proliferation, differentiation, migration, cell 71 death, etc. Physiologically, NR4A members influence the adaptive and innate immune 72 system, angiogenesis, metabolism and brain function. The NR4A family is comprised of 73 three members that bind the same DNA elements (1): NR4A1 (Nur77, TR3, ...

Atypic SUMOylation of Nor1/NR4A3 regulates neural cell viability and redox sensitivity

“…39 Such paradoxical role of SUMOylation remains unexplained, but recent studies in which both sites well conserved in Nur77 were mutated together suggested a combined effect of SUMOylation in regulating Nur77 activity and degradation. 38,72 Consistent with additional SUMOylation that might also occur in Nor1, our results show that the K137R Nor1 mutant still exhibits a SUMOylation signal sensitive to SENP1, strongly supporting the presence of other potential SUMO conjugation site(s) in Nor1. Of the two canonical SUMO motifs found in Nor1, Lys-89 is a likely candidate based on its strong predictive value and homology with Nurr1, but Lys-606 also needs to be considered.…”

“…SUMOylation at Lys‐577 of Nurr1 has been linked to transcriptional activation 71 and transrepression, 12 whereas SUMOylation at Lys‐91, also contained in a canonical ψKxE motif, was associated with transcriptional inhibition 39 . Such paradoxical role of SUMOylation remains unexplained, but recent studies in which both sites well conserved in Nur77 were mutated together suggested a combined effect of SUMOylation in regulating Nur77 activity and degradation 38,72 . Consistent with additional SUMOylation that might also occur in Nor1, our results show that the K137R Nor1 mutant still exhibits a SUMOylation signal sensitive to SENP1, strongly supporting the presence of other potential SUMO conjugation site(s) in Nor1.…”

Deletion of pleiotrophin impairs glucose tolerance and liver metabolism in pregnant mice: Moonlighting role of glycerol kinase

“…In line with this hypothesis, it has been shown that NUR77 degradation is controlled by SUMOylation and later ubiquitination, and that for the SUMOylation of NUR77 the protein must be previously phosphorylated. 39,40 In view of these results, it is tempting to speculate that deletion of Ptn may be associated in the liver with altered transcriptional activity modulated by glycerol kinase, impairing the pregnancy-related adaptations in both glucose and lipid metabolism, including glucose intolerance and a decreased capacity to store lipids (Figure 9). The mouse is an important mammalian model to approach the study of human metabolism in pregnancy, particularly at a molecular level.…”

Regulation of layered T cell tolerance mechanisms by the NR4A family is essential to preserve immune homeostasis and suppress autoimmunity

“…Factors such as IL-2 supply, co-stimulatory signals on distinct APC populations, or developmental context may be instructive (62). Another possible determinant is intensity/duration/biased signal transduction downstream of the TCR itself, which may in turn guide localization of NR4As to the cytosol or nucleus via posttranslational modifications (69).…”