title: Gli protein nuclear localization signal.
abstract: Drosophila cubitus interruptus (Ci) and its vertebrate homologues, the glioblastoma (Gli) protein family, are the transcription factors belonging to the metazoan Gli/Glis/Zic ZF protein superfamily that shares similar five tandemly repeated C2H2-type zinc finger (ZF) motifs. Nuclear transport of Gli/Ci proteins is regulated by hedgehog (Hh) signaling and is an essential part of the Hh signal transduction pathway. Gli/Ci proteins possess a nuclear localization signal (NLS) and a nuclear export signal (NES), both of which are key signatures for controlling nucleocytoplasmic shuttling. The NLS of the Gli/Ci proteins has been mapped to the fifth ZF domain and its C-terminal side. It contains two clusters of basic residues (classical bipartite-type), which are conserved in metazoan Gli/Ci homologues, but which partially deviate from the intra-ZF domain NLSs in the Glis and Zic proteins. Recently, Importin α3 was identified as a nuclear transport protein for Ci. When we modeled the 3D structure of the Gli NLS-Importin α complex, the two basic clusters were predicted to fit in the two binding interfaces of Importin α. The mechanisms controlling the function of NLSs and NESs involve the elimination of the NES by Hh signaling-dependent protein cleavage in the Ci and the Gli3 proteins, and the phosphorylation of a threonine residue close to the NLS in Gli1. Both processes depend on the activity of protein kinase A, which has a critical role in Hh signaling in fly wing discs. In addition, the Roadkill protein, a substrate recognition component of E3 ubiquitin ligase, competes with the Ci protein to interact with Importin α3 resulting in inhibition of Ci protein nuclear import.
authors.affiliation: Laboratory for Behavioral and Developmental Disorders, RIKEN Brain Science Institute, Wako-shi, Saitama, Japan.
authors.forename: Minoru
authors.initials: M
authors.lastname: Hatayama
authors.forename: Jun
authors.initials: J
authors.lastname: Aruga
mesh_terms: D021581:Active Transport, Cell Nucleus / Q000502:physiology; D000595:Amino Acid Sequence; D000818:Animals; D029721:Drosophila Proteins / Q000378:metabolism*; D053823:Hedgehog Proteins / Q000378:metabolism*; D006801:Humans; D015513:Oncogene Proteins / Q000378:metabolism*; D021382:Protein Sorting Signals / Q000502:physiology*; D015398:Signal Transduction / Q000502:physiology; D015534:Trans-Activators / Q000378:metabolism*; D014157:Transcription Factors / Q000378:metabolism; D000071676:Zinc Finger Protein GLI1; D016335:Zinc Fingers / Q000502:physiology*; D028901:alpha Karyopherins / Q000378:metabolism*
chemical_list: D029721:Drosophila Proteins; D053823:Hedgehog Proteins; D015513:Oncogene Proteins; D021382:Protein Sorting Signals; D015534:Trans-Activators; D014157:Transcription Factors; D000071676:Zinc Finger Protein GLI1; D028901:alpha Karyopherins