Browsing by Subject "ubiquitin"

Sort by: Order: Results:

Now showing items 1-4 of 4
  • Yanku, Yifat; Bitman-Lotan, Eliya; Zohar, Yaniv; Kurant, Estee; Zielke, Norman; Eilers, Martin; Orian, Amir (2018)
    The HECT-type ubiquitin ligase HECT, UBA and WWE Domain Containing 1, (HUWE1) regulates key cancer-related pathways, including the Myc oncogene. It affects cell proliferation, stress and immune signaling, mitochondria homeostasis, and cell death. HUWE1 is evolutionarily conserved from Caenorhabditis elegance to Drosophila melanogaster and Humans. Here, we report that the Drosophila ortholog, dHUWE1 (CG8184), is an essential gene whose loss results in embryonic lethality and whose tissue-specific disruption establishes its regulatory role in larval salivary gland development. dHUWE1 is essential for endoreplication of salivary gland cells and its knockdown results in the inability of these cells to replicate DNA. Remarkably, dHUWE1 is a survival factor that prevents premature activation of JNK signaling, thus preventing the disintegration of the salivary gland, which occurs physiologically during pupal stages. This function of dHUWE1 is general, as its inhibitory effect is observed also during eye development and at the organismal level. Epistatic studies revealed that the loss of dHUWE1 is compensated by dMyc proeitn expression or the loss of dmP53. dHUWE1 is therefore a conserved survival factor that regulates organ formation during Drosophila development.
  • Pavicic, Mirko; Mouhu, Katriina; Wang, Feng; Bilicka, Marcelina Marta; Chovanček, Erik; Himanen, Kristiina Irma Helena (2017)
    Flowering time control integrates endogenous as well as environmental signals to promote flower development. The pathways and molecular networks involved are complex and integrate many modes of signal transduction. In plants ubiquitin mediated protein degradation pathway has been proposed to be as important mode of signaling as phosphorylation and transcription. To systematically study the role of ubiquitin signaling in the molecular regulation of flowering we have taken a genomic approach to identify flower related Ubiquitin Proteasome System components. As a large and versatile gene family the RING type ubiquitin E3 ligases were chosen as targets of the genomic screen. To this end the complete list of Arabidopsis RING E3 ligases were retrieved and verified in the Arabidopsis genome v11. Their differential expression was used for their categorization into flower organs or developmental stages. Known regulators of flowering time or floral organ development were identified in these categories through literature search and representative mutants for each category were purchased for functional characterization by growth and morphological phenotyping. To this end, a workflow was developed for high throughput phenotypic screening of growth, morphology and flowering of nearly a thousand Arabidopsis plants in one experimental round.
  • Zachari, Maria; Gudmundsson, Sigurdur R.; Li, Ziyue; Manifava, Maria; Shah, Ronak; Smith, Matthew; Stronge, James; Karanasios, Eleftherios; Piunti, Caterina; Kishi-Itakura, Chieko; Vihinen, Helena; Jokitalo, Eija; Guan, Jun-Lin; Buss, Folma; Smith, Andrew M.; Walker, Simon A.; Eskelinen, Eeva-Liisa; Ktistakis, Nicholas T. (2019)
    The dynamics and co-ordination between autophagy machinery and selective receptors during mitophagy are unknown. Also unknown is whether mitophagy depends on pre-existing membranes, or is triggered on the surface of damaged mitochondria. Using a ubiquitin-dependent mitophagy inducer, the lactone ivermectin, we have combined genetic and imaging experiments to address these questions. Ubiquitination of mitochondrial fragments is required earliest followed by autophosphorylation of TBK1. Next, early essential autophagy proteins FIP200 and ATG13 act at different steps whereas ULK1/2 are dispensable. Receptors act temporally and mechanistically upstream of ATG13 but downstream of FIP200. The VPS34 complex functions at the omegasome step. ATG13 and optineurin target mitochondria in a discontinuous oscillatory way suggesting multiple initiation events. Targeted ubiquitinated mitochondrial are cradled by endoplasmic reticulum strands even without functional autophagy machinery and mitophagy adaptors. We propose that damaged mitochondria are ubiquitinated and dynamically encased in ER strands providing platforms for formation of the mitophagosomes.
  • Lindholm, Katariina Marianne (Helsingin yliopisto, 2015)
    Arabidopsis (Arabidopsis thaliana J. Thal) is a common model species in plant research. Although its genome is completely sequenced, the complete effects of some genes remain undetermined. The aim of this study was to investigate the role of several E3 Ubiquitin (Ub) ligases in Arabidopsis thaliana development through insertional mutant lines from the SALK collection. Sixteen mutant lines in a wild-type Columbia-0 (Col-0) background were subjected to genotyping, and the subsequent confirmed homozygous lines were analyzed for developmental phenotype. Greenhouse experiments were conducted on the wild type Columbia (Col) and sixteen mutant lines. Yield parameters such as days to bolting and silique surface area were studied to identify differences among the mutant lines relative to wild-type. After phenotyping, statistical analysis was performed to determine if there were any significant differences among the lines. The mean of both number of days to bolting and average silique surface area, among line 8, line 9, and line 13b plants, were shown by one way ANOVA to be significantly different than wild-type. These results suggest that those E3 ubiquitin ligases might be involved in the regulation of plant growth and development.