TY - JOUR A1 - Berger, Nathalie A1 - Demolombe, Vincent A1 - Hem, Sonia A1 - Rofidal, Valérie A1 - Steinmann, Laura A1 - Krouk, Gabriel A1 - Crabos, Amandine A1 - Nacry, Philippe A1 - Verdoucq, Lionel A1 - Santoni, Véronique T1 - Root membrane ubiquitinome under short-term osmotic stress JF - International Journal of Molecular Sciences N2 - Osmotic stress can be detrimental to plants, whose survival relies heavily on proteomic plasticity. Protein ubiquitination is a central post-translational modification in osmotic-mediated stress. In this study, we used the K-Ɛ-GG antibody enrichment method integrated with high-resolution mass spectrometry to compile a list of 719 ubiquitinated lysine (K-Ub) residues from 450 Arabidopsis root membrane proteins (58% of which are transmembrane proteins), thereby adding to the database of ubiquitinated substrates in plants. Although no ubiquitin (Ub) motifs could be identified, the presence of acidic residues close to K-Ub was revealed. Our ubiquitinome analysis pointed to a broad role of ubiquitination in the internalization and sorting of cargo proteins. Moreover, the simultaneous proteome and ubiquitinome quantification showed that ubiquitination is mostly not involved in membrane protein degradation in response to short osmotic treatment but that it is putatively involved in protein internalization, as described for the aquaporin PIP2;1. Our in silico analysis of ubiquitinated proteins shows that two E2 Ub-conjugating enzymes, UBC32 and UBC34, putatively target membrane proteins under osmotic stress. Finally, we revealed a positive role for UBC32 and UBC34 in primary root growth under osmotic stress. KW - aquaporin KW - mass spectrometry KW - osmotic stress KW - ubiquitination Y1 - 2022 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-284003 SN - 1422-0067 VL - 23 IS - 4 ER - TY - JOUR A1 - Salat, Daniela A1 - Winkler, Anja A1 - Urlaub, Henning A1 - Gessler, Manfred T1 - Hey bHLH Proteins Interact with a FBXO45 Containing SCF Ubiquitin Ligase Complex and Induce Its Translocation into the Nucleus JF - PLoS One N2 - The Hey protein family, comprising Hey1, Hey2 and HeyL in mammals, conveys Notch signals in many cell types. The helix-loop-helix (HLH) domain as well as the Orange domain, mediate homo- and heterodimerization of these transcription factors. Although distinct interaction partners have been identified so far, their physiological relevance for Hey functions is still largely unclear. Using a tandem affinity purification approach and mass spectrometry analysis we identified members of an ubiquitin E3-ligase complex consisting of FBXO45, PAM and SKP1 as novel Hey1 associated proteins. There is a direct interaction between Hey1 and FBXO45, whereas FBXO45 is needed to mediate indirect Hey1 binding to SKP1. Expression of Hey1 induces translocation of FBXO45 and PAM into the nucleus. Hey1 is a short-lived protein that is degraded by the proteasome, but there is no evidence for FBXO45-dependent ubiquitination of Hey1. On the contrary, Hey1 mediated nuclear translocation of FBXO45 and its associated ubiquitin ligase complex may extend its spectrum to additional nuclear targets triggering their ubiquitination. This suggests a novel mechanism of action for Hey bHLH factors. KW - ubiquitination KW - glycerol KW - transcription factors KW - DNA-binding proteins KW - immunoprecipitation KW - protein interactions KW - protein domains Y1 - 2015 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-125769 VL - 10 IS - 6 ER - TY - JOUR A1 - Peter, Stefanie A1 - Bultinck, Jennyfer A1 - Myant, Kevin A1 - Jaenicke, Laura A. A1 - Walz, Susanne A1 - Müller, Judith A1 - Gmachl, Michael A1 - Treu, Matthias A1 - Boehmelt, Guido A1 - Ade, Casten P. A1 - Schmitz, Werner A1 - Wiegering, Armin A1 - Otto, Christoph A1 - Popov, Nikita A1 - Sansom, Owen A1 - Kraut, Norbert A1 - Eilers, Martin T1 - H Tumor cell-specific inhibition of MYC function using small molecule inhibitors of the HUWE1 ubiquitin ligase JF - EMBO Molecular Medicine N2 - Deregulated expression of MYC is a driver of colorectal carcinogenesis, necessitating novel strategies to inhibit MYC function. The ubiquitin ligase HUWE1 (HECTH9, ARF-BP1, MULE) associates with both MYC and the MYC-associated protein MIZ1. We show here that HUWE1 is required for growth of colorectal cancer cells in culture and in orthotopic xenograft models. Using high-throughput screening, we identify small molecule inhibitors of HUWE1, which inhibit MYC-dependent transactivation in colorectal cancer cells, but not in stem and normal colon epithelial cells. Inhibition of HUWE1 stabilizes MIZ1. MIZ1 globally accumulates on MYC target genes and contributes to repression of MYC-activated target genes upon HUWE1 inhibition. Our data show that transcriptional activation by MYC in colon cancer cells requires the continuous degradation of MIZ1 and identify a novel principle that allows for inhibition of MYC function in tumor cells. KW - colorectal cancer KW - HUWE1 KW - MIZ1 KW - MYC KW - ubiquitination KW - cancer KW - digestive system KW - pharmacology KW - drug discovery Y1 - 2014 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-118132 SN - 1757-4684 VL - 6 IS - 12 ER - TY - JOUR A1 - Cox-Limpens, Kimberly E. M. A1 - Vles, Johan S. H. A1 - van den Hove, Daniel L. A. A1 - Zimmermann, Luc Ji A1 - Gavilanes, Antonio W. D. T1 - Fetal asphyctic preconditioning alters the transcriptional response to perinatal asphyxia JF - BMC Neuroscience N2 - Background: Genomic reprogramming is thought to be, at least in part, responsible for the protective effect of brain preconditioning. Unraveling mechanisms of this endogenous neuroprotection, activated by preconditioning, is an important step towards new clinical strategies for treating asphyctic neonates. Therefore, we investigated whole-genome transcriptional changes in the brain of rats which underwent perinatal asphyxia (PA), and rats where PA was preceded by fetal asphyctic preconditioning (FAPA). Offspring were sacrificed 6 h and 96 h after birth, and whole-genome transcription was investigated using the Affymetrix Gene1.0ST chip. Microarray data were analyzed with the Bioconductor Limma package. In addition to univariate analysis, we performed Gene Set Enrichment Analysis (GSEA) in order to derive results with maximum biological relevance. Results: We observed minimal, 25% or less, overlap of differentially regulated transcripts across different experimental groups which leads us to conclude that the transcriptional phenotype of these groups is largely unique. In both the PA and FAPA group we observe an upregulation of transcripts involved in cellular stress. Contrastingly, transcripts with a function in the cell nucleus were mostly downregulated in PA animals, while we see considerable upregulation in the FAPA group. Furthermore, we observed that histone deacetylases (HDACs) are exclusively regulated in FAPA animals. Conclusions: This study is the first to investigate whole-genome transcription in the neonatal brain after PA alone, and after perinatal asphyxia preceded by preconditioning (FAPA). We describe several genes/pathways, such as ubiquitination and proteolysis, which were not previously linked to preconditioning-induced neuroprotection. Furthermore, we observed that the majority of upregulated genes in preconditioned animals have a function in the cell nucleus, including several epigenetic players such as HDACs, which suggests that epigenetic mechanisms are likely to play a role in preconditioning-induced neuroprotection. KW - Perinatal Asphyxia KW - oxidative stress KW - microarray KW - cerebral artery occlusion KW - ischemic brain injury KW - genomic response KW - protein aggregation KW - immediate early genes KW - neuroprotection KW - tolerance KW - rat KW - expression KW - transient global ischemia KW - ubiquitination KW - epigenetics KW - fetal preconditioning KW - neonatal brain Y1 - 2014 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-116185 VL - 15 ER -