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Scholz, Carsten C.
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Scholz, Carsten C.
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Scholz, Carsten C.
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Now showing 1 - 4 of 4
- PublicationFIH Regulates Cellular Metabolism through Hydroxylation of the Deubiquitinase OTUB1(Public Library of Science, 2016-01-11)
; ; ; ; ; ; ; ; ; The asparagine hydroxylase, factor inhibiting HIF (FIH), confers oxygen-dependence upon the hypoxia-inducible factor (HIF), a master regulator of the cellular adaptive response to hypoxia. Studies investigating whether asparagine hydroxylation is a general regulatory oxygen-dependent modification have identified multiple non-HIF targets for FIH. However, the functional consequences of this outside of the HIF pathway remain unclear. Here, we demonstrate that the deubiquitinase ovarian tumor domain containing ubiquitin aldehyde binding protein 1 (OTUB1) is a substrate for hydroxylation by FIH on N22. Mutation of N22 leads to a profound change in the interaction of OTUB1 with proteins important in cellular metabolism. Furthermore, in cultured cells, overexpression of N22A mutant OTUB1 impairs cellular metabolic processes when compared to wild type. Based on these data, we hypothesize that OTUB1 is a target for functional hydroxylation by FIH. Additionally, we propose that our results provide new insight into the regulation of cellular energy metabolism during hypoxic stress and the potential for targeting hydroxylases for therapeutic benefit.294Scopus© Citations 74 - PublicationHydroxylase-dependent regulation of the NF-κB pathwayHypoxia is associated with a diverse range of physiological and pathophysiological processes, including development, wound healing, inflammation, vascular disease and cancer. The requirement that eukaryotic cells have for molecular oxygen as the terminal electron acceptor for the electron transport chain means that the maintenance of oxygen delivery is key for bioenergetic homeostasis. Metazoans have evolved an effective way to adapt to hypoxic stress at the molecular level through a transcription factor termed the hypoxia inducible factor. A family of oxygen-sensing hydroxylases utilizes molecular oxygen as a co-substrate for the hydroxylation of hypoxia inducible factor α subunits, thereby reducing its expression and transcriptional activity when oxygen is available. Recent studies have indicated that other hypoxia-responsive transcriptional pathways may also be hydroxylase-dependent. In this review, we will discuss the role of hydroxylases in the regulation of NF-κB, a key regulator of immunity and inflammation. Developing our understanding of the role of hydroxylases in hypoxic inflammation may identify novel therapeutic approaches in chronic inflammatory disease.
503Scopus© Citations 36 - PublicationA dynamic model of the hypoxia-inducible factor 1 (HIF-1α) network(The Company of Biologists, 2013-02-06)
; ; ; Activation of the hypoxia-inducible factor (HIF) pathway is a critical step in the transcriptional response to hypoxia. Although many of the key proteins involved have been characterised, the dynamics of their interactions in generating this response remain unclear. In the present study, we have generated a comprehensive mathematical model of the HIF-1α pathway based on core validated components and dynamic experimental data, and confirm the previously described connections within the predicted network topology. Our model confirms previous work demonstrating that the steps leading to optimal HIF-1α transcriptional activity require sequential inhibition of both prolyl- and asparaginyl-hydroxylases. We predict from our model (and confirm experimentally) that there is residual activity of the asparaginyl-hydroxylase FIH (factor inhibiting HIF) at low oxygen tension. Furthermore, silencing FIH under conditions where prolyl-hydroxylases are inhibited results in increased HIF-1α transcriptional activity, but paradoxically decreases HIF-1α stability. Using a core module of the HIF network and mathematical proof supported by experimental data, we propose that asparaginyl hydroxylation confers a degree of resistance upon HIF-1α to proteosomal degradation. Thus, through in vitro experimental data and in silico predictions, we provide a comprehensive model of the dynamic regulation of HIF-1α transcriptional activity by hydroxylases and use its predictive and adaptive properties to explain counter-intuitive biological observations.366Scopus© Citations 97 - PublicationRegulation of IL-1β-induced NF-κB by hydroxylases links key hypoxic and inflammatory signaling pathways(National Academy of Sciences, 2013-10)
; ; ; ; ; ; ; ; ; ; ; Hypoxia is a prominent feature of chronically inflamed tissues. Oxygen-sensing hydroxylases control transcriptional adaptation to hypoxia through the regulation of hypoxia-inducible factor (HIF) and nuclear factor κB (NF-κB), both of which can regulate the inflammatory response. Furthermore, pharmacologic hydroxylase inhibitors reduce inflammation in multiple animal models. However, the underlying mechanism(s) linking hydroxylase activity to inflammatory signaling remains unclear. IL-1β, a major proinflammatory cytokine that regulates NF-κB, is associated with multiple inflammatory pathologies. We demonstrate that a combination of prolyl hydroxylase 1 and factor inhibiting HIF hydroxylase isoforms regulates IL-1β-induced NF-κB at the level of (or downstream of) the tumor necrosis factor receptor-associated factor 6 complex. Multiple proteins of the distal IL-1β-signaling pathway are subject to hydroxylation and form complexes with either prolyl hydroxylase 1 or factor inhibiting HIF. Thus, we hypothesize that hydroxylases regulate IL-1β signaling and subsequent inflammatory gene expression. Furthermore, hydroxylase inhibition represents a unique approach to the inhibition of IL-1β-dependent inflammatory signaling.272Scopus© Citations 142