Interaction with factor inhibiting HIF-1 defines an additional mode of cross-coupling between the Notch and hypoxia signaling pathways

• DOI: 10.1073/pnas.0711591105
• Publication Date: 2008-02-26T02:27:45Z
• Authors: Xiaofeng Zheng; Sarah Linke; José M. Dias; Xiaowei Zheng; Katarina Gradin; Tristan P. Wallis; Brett R. Hamilton; Maria Gustafsson; Jorge L. Ruas; Sarah Wilkins; Rebecca L. Bilton; Kerstin Brismar; Murray L. Whitelaw; Teresa Pereira; Jeffrey J. Gorman; Johan Ericson; Daniel J. Peet; Urban Lendahl; Lorenz Poellinger
• Keywords: 0301 basic medicine; 570; Notch; Chick Embryo; Signal transduction; Transfection; alpha Subunit; Hydroxylation; Muscle Development; Cell Line; Mixed Function Oxygenases; Mice; 03 medical and health sciences; Proto-Oncogene Proteins; Receptors; Animals; Humans; Receptor, Notch2; Receptor, Notch1; Hypoxia; Receptor, Notch4; Receptor, Notch3; Notch2; Notch1; Receptors, Notch; Notch4; Notch3; Receptor Cross-Talk; Hypoxia-Inducible Factor 1, alpha Subunit; Gene regulation; 3. Good health; Repressor Proteins; 1000 General; Hypoxia-Inducible Factor 1; Receptor; Signal Transduction; Transcription Factors

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.