ORCID Profile
0000-0003-1347-3328
Current Organisation
University of Oxford
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Publisher: Proceedings of the National Academy of Sciences
Date: 04-03-2008
Abstract: Cells adapt to hypoxia by a cellular response, where hypoxia-inducible factor 1α (HIF-1α) becomes stabilized and directly activates transcription of downstream genes. In addition to this “canonical” response, certain aspects of the pathway require integration with Notch signaling, i.e., HIF-1α can interact with the Notch intracellular domain (ICD) to augment the Notch downstream response. In this work, we demonstrate an additional level of complexity in this cross-talk: factor-inhibiting HIF-1 (FIH-1) regulates not only HIF activity, but also the Notch signaling output and, in addition, plays a role in how Notch signaling modulates the hypoxic response. We show that FIH-1 hydroxylates Notch ICD at two residues (N 1945 and N 2012 ) that are critical for the function of Notch ICD as a transactivator within cells and during neurogenesis and myogenesis in vivo . FIH-1 negatively regulates Notch activity and accelerates myogenic differentiation. In its modulation of the hypoxic response, Notch ICD enhances recruitment of HIF-1α to its target promoters and derepresses HIF-1α function. Addition of FIH-1, which has a higher affinity for Notch ICD than for HIF-1α, abrogates the derepression, suggesting that Notch ICD sequesters FIH-1 away from HIF-1α. In conclusion, the data reveal posttranslational modification of the activated form of the Notch receptor and an intricate mode of cross-coupling between the Notch and hypoxia signaling pathways.
Publisher: Wiley
Date: 21-03-2016
Publisher: Elsevier BV
Date: 07-2009
DOI: 10.1016/J.BIOCEL.2009.01.005
Abstract: FIH-1, factor inhibiting hypoxia-inducible factor-1 (HIF-1), regulates oxygen sensing by hydroxylating an asparagine within HIF-alpha. It also hydroxylates asparagines in many proteins containing ankyrin repeats, including Notch1-3, p105 and I?B?. Relative binding affinity and hydroxylation rate are crucial determinants of substrate selection and modification. We determined the contributions of substrate sequence composition and length and of oxygen concentration to the FIH-1-binding and/or hydroxylation of Notch1-4 and compared them with those for HIF-1alpha. We also demonstrated hydroxylation of two asparagines in Notch2 and 3, corresponding to Sites 1 and 2 of Notch1, by mass spectrometry for the first time. Our data demonstrate that substrate length has a much greater influence on FIH-1-dependent hydroxylation of Notch than of HIF-1alpha, predominantly through binding affinity rather than maximal reaction velocity. The K(m) value of FIH-1 for Notch1, < 0.2 microM, is at least 250-fold lower than that of 50 microM for HIF-1alpha. Site 1 of Notch1-3 appeared the preferred site of FIH-1 hydroxylation in these substrates. Interestingly, binding of Notch4 to FIH-1 was observed with an affinity almost 10-fold lower than for Notch1-3, but no hydroxylation was detected. Importantly, we demonstrate that the K(m) of FIH-1 for oxygen at the preferred Site 1 of Notch1-3, 10-19 microM, is an order of magnitude lower than that for Site 2 or HIF-1alpha. Hence, at least during in vitro hydroxylation, Notch is likely to become efficiently hydroxylated by FIH-1 even under relatively severe hypoxic conditions, where HIF-1alpha hydroxylation would be reduced.
Publisher: Elsevier BV
Date: 08-2015
Publisher: Informa UK Limited
Date: 07-2020
Publisher: Elsevier BV
Date: 02-2014
Publisher: Oxford University Press (OUP)
Date: 16-10-2014
DOI: 10.1093/JAC/DKU403
Location: United Kingdom of Great Britain and Northern Ireland
No related grants have been discovered for Sarah Wilkins.