Interaction with factor inhibiting HIF-1 defines an additional mode of cross-coupling between the Notch and hypoxia signaling pathways.
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Zheng X, Linke S, Dias JM, Zheng X, Gradin K, Wallis TP, Hamilton BR, Gustafsson M, Ruas JL, Wilkins S, Bilton RL, Brismar K, Whitelaw ML, Pereira T, Gorman JJ, Ericson J, Peet DJ, Lendahl U, Poellinger L
Interaction with factor inhibiting HIF-1 defines an additional mode of cross-coupling between the Notch and hypoxia signaling pathways.
Proc Natl Acad Sci U S A. 2008 Mar 4;105(9):3368-73. doi: 10.1073/pnas.0711591105. Epub 2008 Feb 25.
- PubMed ID
- 18299578 [ View in PubMed]
- Abstract
Cells adapt to hypoxia by a cellular response, where hypoxia-inducible factor 1alpha (HIF-1alpha) 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-1alpha 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-1alpha to its target promoters and derepresses HIF-1alpha function. Addition of FIH-1, which has a higher affinity for Notch ICD than for HIF-1alpha, abrogates the derepression, suggesting that Notch ICD sequesters FIH-1 away from HIF-1alpha. 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.