title: The role of MITF phosphorylation sites during coat color and eye development in mice analyzed by bacterial artificial chromosome transgene rescue.
abstract: The microphthalmia-associated transcription factor (Mitf) has emerged as an important model for gene regulation in eukaryotic organisms. In vertebrates, it regulates the development of several cell types including melanocytes and has also been shown to play an important role in melanoma. In vitro, the activity of MITF is regulated by multiple signaling pathways, including the KITL/KIT/B-Raf pathway, which results in phosphorylation of MITF on serine residues 73 and 409. However, the precise role of signaling to MITF in vivo remains largely unknown. Here, we use a BAC transgene rescue approach to introduce specific mutations in MITF to study the importance of specific phospho-acceptor sites and protein domains. We show that mice that carry a BAC transgene where single-amino-acid substitutions have been made in the Mitf gene rescue the phenotype of the loss-of-function mutations in Mitf. This may indicate that signaling from KIT to MITF affects other phospho-acceptor sites in MITF or that alternative sites can be phosphorylated when Ser73 and Ser409 have been mutated. Our results have implications for understanding signaling to transcription factors. Furthermore, as MITF and signaling mechanisms have been shown to play an important role in melanomas, our findings may lead to novel insights into this resilient disease.
authors.affiliation: Department of Biochemistry and Molecular Biology, Biomedical Center, Faculty of Medicine, University of Iceland, Reykjavik, Iceland.
authors.forename: Georg L
authors.initials: GL
authors.lastname: Bauer
authors.forename: Christian
authors.initials: C
authors.lastname: Praetorius
authors.forename: Kristín
authors.initials: K
authors.lastname: Bergsteinsdóttir
authors.forename: Jón H
authors.initials: JH
authors.lastname: Hallsson
authors.forename: Bryndís K
authors.initials: BK
authors.lastname: Gísladóttir
authors.forename: Alexander
authors.initials: A
authors.lastname: Schepsky
authors.forename: Deborah A
authors.initials: DA
authors.lastname: Swing
authors.forename: T Norene
authors.initials: TN
authors.lastname: O'Sullivan
authors.forename: Heinz
authors.initials: H
authors.lastname: Arnheiter
authors.forename: Keren
authors.initials: K
authors.lastname: Bismuth
authors.forename: Julien
authors.initials: J
authors.lastname: Debbache
authors.forename: Colin
authors.initials: C
authors.lastname: Fletcher
authors.forename: Søren
authors.initials: S
authors.lastname: Warming
authors.forename: Neal G
authors.initials: NG
authors.lastname: Copeland
authors.forename: Nancy A
authors.initials: NA
authors.lastname: Jenkins
authors.forename: Eiríkur
authors.initials: E
authors.lastname: Steingrímsson
mesh_terms: D017398:Alternative Splicing; D000818:Animals; D001665:Binding Sites / Q000235:genetics; D022202:Chromosomes, Artificial, Bacterial / Q000235:genetics*; D005091:Exons / Q000235:genetics; D005123:Eye / Q000254:growth & development / Q000378:metabolism*; D005260:Female; D017353:Gene Deletion; D006200:Hair Color / Q000235:genetics*; D008297:Male; D008544:Melanocytes / Q000378:metabolism; D051379:Mice; D008822:Mice, Transgenic; D051739:Microphthalmia-Associated Transcription Factor / Q000235:genetics* / Q000378:metabolism; D009154:Mutation; D009206:Myocardium / Q000378:metabolism; D010641:Phenotype; D010766:Phosphorylation; D012694:Serine / Q000235:genetics / Q000378:metabolism; D012867:Skin / Q000254:growth & development / Q000378:metabolism; D019076:Transgenes / Q000235:genetics*
chemical_list: D051739:Microphthalmia-Associated Transcription Factor; D012694:Serine