title: Intracellular trafficking and dynamics of double homeodomain proteins.
abstract: Double homeodomain (DUX) proteins are encoded by a family of 3.3-kilobase repeated elements dispersed in the human genome. One of these elements named D4Z4 is found in a tandem repeat array on chromosome 4 that is partially deleted in facioscapulohumeral muscular dystrophy. We have evaluated the trafficking and mobility of two DUX proteins, DUX1 and DUX4. We transfected C2C12 myoblasts with cDNA encoding these proteins fused to the green fluorescent protein and studied their intracellular localization and diffusional mobilities using fluorescence recovery after photobleaching and fluorescence loss in photobleaching. We also studied truncated forms of the proteins, containing one or both homeodomains or a region outside the homeodomains. We show that both full-length proteins are actively transported into the nucleus, and that the homeodomains contain the signals required for this localization. DUX1 is more mobile than DUX4 within the nucleus (t(1/2) = 4.8 s for DUX1 and 13.4 s for DUX4), suggesting differences in the way the two proteins interact with nuclear components.
authors.affiliation: Department of Medicine, College of Physicians and Surgeons, Columbia University, Room 10-509, 630 West 168th Street, New York, New York 10032, USA.
authors.forename: Cecilia
authors.initials: C
authors.lastname: Ostlund
authors.forename: Ruth M
authors.initials: RM
authors.lastname: Garcia-Carrasquillo
authors.forename: Alexandra
authors.initials: A
authors.lastname: Belayew
authors.forename: Howard J
authors.initials: HJ
authors.lastname: Worman
mesh_terms: D021581:Active Transport, Cell Nucleus / Q000235:genetics; D000595:Amino Acid Sequence; D002460:Cell Line; D002467:Cell Nucleus / Q000235:genetics / Q000378:metabolism*; D018398:Homeodomain Proteins / Q000235:genetics / Q000378:metabolism*; D006801:Humans; D007424:Intracellular Fluid / Q000378:metabolism*; D018613:Microscopy, Confocal; D008856:Microscopy, Fluorescence; D008969:Molecular Sequence Data; D019913:Nuclear Localization Signals / Q000235:genetics / Q000378:metabolism; D009687:Nuclear Proteins / Q000235:genetics / Q000378:metabolism; D013816:Thermodynamics; D014162:Transfection
chemical_list: C115599:DUX1 protein, human; C121257:DUX4L1 protein, human; D018398:Homeodomain Proteins; D019913:Nuclear Localization Signals; D009687:Nuclear Proteins