Project description:We used microarrays to detail the global program of gene expression underlying SAG-dependent neddylation and identified distinct classes of disparate genes during this process.
Project description:Neddylation is necessary for activation of Cullin-RING Ligases (CRLs) which degrade various immune regulatory proteins. Our recent study showed that while depletion of neddylation E2-E3 pair Ube2f-Sag in regulatory T cells (Treg cells) had no obvious phenotype, the same depletion of either Ube2m or Rbx1 caused inflammation disorders with different severity. Whether these E2s or E3s compensate each other in functional regulations of Treg cells is, however, previously unknown. In this report, we generated Foxp3Cre;Ube2mfl/fl;Ube2ffl/fl or Foxp3Cre;Rbx1fl/fl;Sagfl/fl double null mice by simultaneously deletion of both neddylation E2s or E3s in Treg cells, respectively. Remarkably, Ube2m&Ube2f double null mice developed much severe autoimmune phenotypes than Ube2m-null mice, indicating Ube2m significantly compensates Ube2f in Treg cells. The minor worsen autoimmune phenotypes seen at very early stage in Rbx1&Sag double null than Rbx1-null mice, is likely due to already severe phenotypes of the later, indicating a minor compensation of Rbx1 for Sag. The RNA profiling-based analyses revealed that up- and down-regulations of few signaling pathways in Treg cells are associated with the severity of autoimmune phenotypes. Finally, severer inflammation phenotypes seen in mice with double E3-null than with double E2-null Treg cells indicate a neddylation-independent mechanism of two E3s, also known to serve as the RING component of CRLs in regulation of Treg cell fitness.
Project description:Human fibroblasts from a control or a patient with compound heterozygous variants in KIAA0753 treated with SAG or WNT3A to test responses within canonical Hedgehog or WNT signaling.
Project description:Hereditary Spastic Paraplegia (HSP) is a neurodegenerative disease most commonly caused by autosomal dominant mutations in the SPG4 gene encoding the microtubule severing protein spastin. We hypothesise that SPG4-HSP is attributable to reduced spastin function due to haploinsufficiency, thus therapeutic approaches which elevate levels of the wild type spastin allele may be an effective therapy. However until now, how spastin levels are regulated is largely unknown. Here, we show that the kinase HIPK2 regulates spastin protein levels in proliferating cells, in differentiated neurons and in vivo. Our work reveals that HIPK2-mediated phosphorylation of spastin at S268 inhibits spastin K48-poly-ubiquitination at K554 and prevents its neddylation-dependent proteasomal degradation. In a spastin RNAi neuronal cell model, overexpression of HIPK2, or inhibition of neddylation, restores spastin levels and rescues neurite defects. Notably, we demonstrate that spastin levels can be restored pharmacologically by inhibiting its neddylation-mediated degradation in neurons derived from a spastin mouse model of HSP and in patient derived cells, thus revealing novel therapeutic targets for the treatment of SPG4-HSP. We do not know how S268 phosphorylation prevents spastin ubiquitination at K554; we hypothesised that phosphorylation can protect spastin from polyubiquitination by impairing the recruitment of proteins belonging to ubiquitination pathway or by promoting the interactions with factors that mask spastin region necessary for efficient ubiquitination/degradation. To have insight about these hypotheses, we analysed by mass spectrometry (MS) the interactome of spastin-S268A and -S268D upon overexpression in HeLa cells.
Project description:Myelination is essential for neuronal function and health. In peripheral nerves, >100 causative mutations have been identified that cause Charcot-Marie-Tooth disease, a disorder that can affect myelin sheaths. Among these, a number of mutations are related to essential targets of the post-translation modification neddylation, although how these lead to myelin defects is unclear. Here, we demonstrate that inhibiting neddylation leads to a striking absence of peripheral myelin and axonal loss both in developing and regenerating mouse nerves. Importantly, our data indicate that neddylation exerts a global influence on the complex transcriptional and post-transcriptional program by simultaneously regulating the expression and function of multiple essential myelination signals, including the master transcription factor EGR2 and the negative regulators c-Jun and Sox2, and inducing global secondary changes in downstream pathways, including the mTOR and YAP/TAZ signalling pathways. This places neddylation as a critical regulator of myelination and delineates the potential pathogenic mechanisms involved in CMT mutations related to neddylation.
Project description:Neddylation is necessary for activation of Cullin-RING Ligases (CRLs) which degrade various immune regulatory proteins. Our recent study showed that while depletion of neddylation E2-E3 pair Ube2f-Sag in regulatory T cells (Treg cells) had no obvious phenotype, the same depletion of either Ube2m or Rbx1 caused inflammation disorders with different severity. Whether these E2s or E3s compensate each other in functional regulations of Treg cells is, however, previously unknown. In this report, we generated Foxp3Cre;Ube2mfl/fl;Ube2ffl/fl or Foxp3Cre;Rbx1fl/fl;Sagfl/fl double null mice by simultaneously deletion of both neddylation E2s or E3s in Treg cells, respectively. Remarkably, Ube2m&Ube2f double null mice developed much severe autoimmune phenotypes than Ube2m-null mice, indicating Ube2m significantly compensates Ube2f in Treg cells. The minor worsen autoimmune phenotypes seen at very early stage in Rbx1&Sag double null than Rbx1-null mice, is likely due to already severe phenotypes of the later, indicating a minor compensation of Rbx1 for Sag. The RNA profiling-based analyses revealed that up- and down-regulations of few signaling pathways in Treg cells are associated with the severity of autoimmune phenotypes. Finally, severer inflammation phenotypes seen in mice with double E3-null than with double E2-null Treg cells indicate a neddylation-independent mechanism of two E3s, also known to serve as the RING component of CRLs in regulation of Treg cell fitness.
Project description:Hypoxia, an inadequate supply of tissue oxygen tension, has been reported to induce apoptosis of spermatogenic cells and is associated with male infertility. Neddylation, a post-translational modification similar to ubiquitination, has been shown to be involved in the hypoxia stress response. However, the functions of neddylation in hypoxia-induced apoptosis of spermatogenic cells and its association with male infertility remain largely unexplored. In this study, aiming to explore the role of neddylation in male infertility, we used the specific neddylation inhibitor MLN4924 for treatment in mouse type B spermatogonia GC-2 cells. Our results showed that MLN4924 had no apparent effect on GC-2 cell apoptosis under normoxia, but significantly increased apoptotic cells under hypoxia. Transcriptomic analysis and qPCR assay confirmed that MLN4924 could suppress the expression of hypoxia target genes in GC-2 cells under hypoxia. In addition, MLN4924 could enhance the induction of intracellular and mitochondrial reactive oxygen species (ROS) under hypoxia. These results indicate that the neddylation inhibitor MLN4924 potentiates hypoxia-induced apoptosis of mouse type B spermatogonia GC-2 cells, and neddylation may play an important role in promoting spermatogenic cells to adapt to hypoxia stress.