title: The myeloid leukemia factor interacts with COP9 signalosome subunit 3 in Drosophila melanogaster.
abstract: The human myeloid leukemia factor 1 (hMLF1) gene was first identified as an NPM-hMLF1 fusion gene produced by chromosomal translocation. In Drosophila, dMLF has been identified as a protein homologous to hMLF1 and hMLF2, which interacts with various factors involved in transcriptional regulation. However, the precise cellular function of dMLF remains unclear. To generate further insights, we first examined the behavior of dMLF protein using an antibody specific to dMLF. Immunostaining analyses showed that dMLF localizes in the nucleus in early embryos and cultured cells. Ectopic expression of dMLF in the developing eye imaginal disc using eyeless-GAL4 driver resulted in a small-eye phenotype and co-expression of cyclin E rescued the small-eye phenotype, suggesting the involvement of dMLF in cell-cycle regulation. We therefore analyzed the molecular mechanism of interactions between dMLF and a dMLF-interacting protein, dCSN3, a subunit of the COP9 signalosome, which regulates multiple signaling and cell-cycle pathways. Biochemical and genetic analyses revealed that dMLF interacts with dCSN3 in vivo and glutathione S-transferase pull-down assays revealed that the PCI domain of the dCSN3 protein is sufficient for this to occur, possibly functioning as a structural scaffold for assembly of the COP9 signalosome complex. From these data we propose the possibility that dMLF plays a negative role in assembly of the COP9 signalosome complex.
authors.affiliation: Department of Applied Biology, Kyoto Institute of Technology, Japan.
authors.forename: Wakana
authors.initials: W
authors.lastname: Sugano
authors.forename: Katsuhito
authors.initials: K
authors.lastname: Ohno
authors.forename: Noriko
authors.initials: N
authors.lastname: Yoneda-Kato
authors.forename: Jun-ya
authors.initials: JY
authors.lastname: Kato
authors.forename: Masamitsu
authors.initials: M
authors.lastname: Yamaguchi
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D000075686:COP9 Signalosome Complex; D002453:Cell Cycle / Q000235:genetics / Q000502:physiology; D002478:Cells, Cultured; D029721:Drosophila Proteins / Q000235:genetics / Q000378:metabolism*; D004331:Drosophila melanogaster / Q000166:cytology / Q000235:genetics / Q000378:metabolism*; D015870:Gene Expression; D005982:Glutathione Transferase / Q000235:genetics / Q000378:metabolism; D015151:Immunoblotting; D007150:Immunohistochemistry; D047468:Immunoprecipitation; D008969:Molecular Sequence Data; D046912:Multiprotein Complexes / Q000235:genetics / Q000378:metabolism*; D009687:Nuclear Proteins / Q000235:genetics / Q000378:metabolism*; D010447:Peptide Hydrolases / Q000235:genetics / Q000378:metabolism*; D011485:Protein Binding; D011494:Protein Kinases / Q000235:genetics / Q000378:metabolism*; D011993:Recombinant Fusion Proteins / Q000235:genetics / Q000378:metabolism; D020133:Reverse Transcriptase Polymerase Chain Reaction; D017386:Sequence Homology, Amino Acid; D014162:Transfection
chemical_list: D029721:Drosophila Proteins; C468117:Mlf protein, Drosophila; D046912:Multiprotein Complexes; D009687:Nuclear Proteins; D011993:Recombinant Fusion Proteins; D005982:Glutathione Transferase; D011494:Protein Kinases; D010447:Peptide Hydrolases; D000075686:COP9 Signalosome Complex