Nuclear localization of magphinins, alternative splicing products of the human trophinin gene.
Human magphinin proteins are translation products of differentially spliced transcripts from the 5' region of the human trophinin gene (TRO), whose 3' region encodes trophinin, a unique cell adhesion molecule involved in human embryo implantation. Magphinins belong to the MAGE (melanoma-associated antigen) family, and a previous study of mouse magphinins showed their expression in male and female germ cells, suggesting a role in germ cell development. Here, we characterized the structure and subcellular localization of human magphinins. Confocal microscopy analysis of ectopically expressed magphinins revealed that magphinin-alpha and -beta localize in the cytoplasm, whereas magphinin-gamma lacking the peptide encoded by exon-3 is nuclear. Following Triton X-100 extraction, DNA digestion, and high salt extraction magphinin-gamma remained nuclear, suggesting strong association with the nuclear matrix. A series of magphinin-gamma deletion mutants were generated and assayed for localization, which showed that the N-terminal region of the MAGE homology domain is necessary for nuclear localization. When magphinin-gamma was expressed in NIH3T3 cells, cells underwent G1 arrest. These results suggest that human magphinin-gamma inhibits cell cycle progression through nuclear activity.
Aoyama
Junya
J
Department of Molecular Cell Biology, Graduate School of Pharmaceutical Sciences, Chiba University, Chiba 260-8675, Japan.
Akazawa
Yusuke
Y
Kasahara
Kousuke
K
Higashiyama
Yukihiro
Y
Kikuchi
Ikue
I
Fukumoto
Yasunori
Y
Saburi
Sakura
S
Nakayama
Yuji
Y
Fukuda
Michiko N
MN
Yamaguchi
Naoto
N
D017398:Alternative Splicing / Q000502:physiology*; D000818:Animals; D019556:COS Cells; D015815:Cell Adhesion Molecules / Q000032:analysis* / Q000737:chemistry / Q000502:physiology; D002453:Cell Cycle / Q000502:physiology; D016923:Cell Death / Q000502:physiology; D002467:Cell Nucleus / Q000737:chemistry* / Q000502:physiology; D002478:Cells, Cultured; D002522:Chlorocebus aethiops; D003593:Cytoplasm / Q000737:chemistry* / Q000502:physiology; D005091:Exons; D005260:Female; D006801:Humans; D007438:Introns; D008297:Male; D051379:Mice; D018613:Microscopy, Confocal; D041681:NIH 3T3 Cells; D019913:Nuclear Localization Signals / Q000502:physiology*
D015815:Cell Adhesion Molecules; D019913:Nuclear Localization Signals; C093649:TRO protein, human; C445321:trophinin, mouse