title: Separate necdin domains bind ARNT2 and HIF1alpha and repress transcription.
abstract: PWS is caused by the loss of expression of a set of maternally imprinted genes including NECDIN (NDN). NDN is expressed in post-mitotic neurons and plays an essential role in PWS as mouse models lacking only the Ndn gene mimic aspects of this disease. Patients haploid for SIM1 develop a PW-like syndrome. Here, we report that NDN directly interacts with ARNT2, a bHLH-PAS protein and dimer partner for SIM1. We also found that NDN can interact with HIF1alpha. We showed that NDN can repress transcriptional activation mediated by ARNT2:SIM1 as well as ARNT2:HIF1alpha. The N-terminal 115 residues of NDN are sufficient for interaction with the bHLH domains of ARNT2 or HIF1alpha but not for transcriptional repression. Using GAL4-NDN fusion proteins, we determined that NDN possesses multiple repression domains. We thus propose that NDN regulates neuronal function and hypoxic response by regulating the activities of the ARNT2:SIM1 and ARNT2:HIF1alpha dimers, respectively.
authors.affiliation: Department of Embryology, Carnegie Institution of Washington, 3520 San Martin Drive, Baltimore, MD 21218, USA.
authors.forename: Eitan R
authors.initials: ER
authors.lastname: Friedman
authors.forename: Chen-Ming
authors.initials: CM
authors.lastname: Fan
mesh_terms: D051784:Aryl Hydrocarbon Receptor Nuclear Translocator / Q000378:metabolism*; D051792:Basic Helix-Loop-Helix Proteins; D001665:Binding Sites; D002460:Cell Line; D006801:Humans; D051795:Hypoxia-Inducible Factor 1, alpha Subunit / Q000378:metabolism*; D007668:Kidney / Q000378:metabolism*; D009419:Nerve Tissue Proteins / Q000378:metabolism*; D009687:Nuclear Proteins / Q000378:metabolism*; D011485:Protein Binding; D017434:Protein Structure, Tertiary; D012097:Repressor Proteins / Q000378:metabolism*; D014158:Transcription, Genetic / Q000502:physiology*; D015533:Transcriptional Activation / Q000502:physiology*