C-terminus of desmoyokin/AHNAK protein is responsible for its translocation between the nucleus and cytoplasm

Zhuxiang Nie, Wang Ning, Masayuki Amagai, Takashi Hashimoto

Research output: Contribution to journalArticle

34 Citations (Scopus)

Abstract

We previously demonstrated that desmoyokin gene is identical to AHNAK gene, which is downregulated in neuroblastomas. Whereas desmoyokin/AHNAK protein is distributed in the nucleus and cytoplasm in nonepithelial tissues, it is distributed in the cell membrane in epithelial tissues. It is present diffusely in the cytoplasm and nucleus of epithelial cell lines cultured in low calcium condition. Low to normal calcium shift translocates it to the cell boundary. In this study, we investigated which domain(s) of desmoyokin/AHNAK protein are responsible for its different distribution. We constructed three different eukaryotic expression plasmids, pN-DY, pM-DY, and pC-DY, which expressed N-terminus, central domain, and C-terminus of this molecule, respectively, when transfected into COS-7 cells, normal human keratinocytes, and HeLa cells. In normal calcium medium, whereas N-terminus and central domain of desmoyokin/AHNAK protein were present mainly in the cytoplasm, C-terminus was present in the nucleus, cytoplasm, and weakly in the cell membrane. In low calcium medium, C-terminus was present exclusively in the nucleus, and a part of the molecules translocated from the nucleus to the cytoplasm, 3 h after the shift to normal calcium medium or 3 h after addition of protein kinase C activator, 12-O-tetradecanoylphorbol-13-acetate in low calcium medium. Calcium shift showed no effects on the distribution of N-terminus and central domain. These results suggested that C-terminus, but neither N-terminus nor central domain, is responsible for the translocation of this protein into the nucleus. This study may also suggest that C-terminus play a role in the translocation to the cell membrane, although further evidence is necessary.

Original languageEnglish
Pages (from-to)1044-1049
Number of pages6
JournalJournal of Investigative Dermatology
Volume114
Issue number5
DOIs
Publication statusPublished - 2000 Jan 1

Keywords

  • Desmosome
  • Keratinocyte
  • Signal transduction
  • cDNA

ASJC Scopus subject areas

  • Biochemistry
  • Molecular Biology
  • Dermatology
  • Cell Biology

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