Interaction of protein phosphatase 1 delta with nucleolin in human osteoblastic cells

Hiroyuki Morimoto, Hirohiko Okamura, Tatsuji Haneji

Research output: Contribution to journalArticlepeer-review

21 Citations (Scopus)


We examined the expression and cytolocalization of the protein phosphatase type 1 delta (PP1δ) isoform and nucleolin in human osteoblastic MG63 and Saos-2 cells. Cellular fractionation of MG63 cells was done and protein was prepared from each fraction. Anti-nucleolin antibody interacted with the 100- and 95-kD proteins present in the whole-cell lysate. The 100-kD protein was detected in nuclear and nucleolar fractions. The 95-kD protein was detected in cytosolic and nucleoplasmic fractions. PP1δ and nucleolin were colocalized in the nucleolus in MG63 and Saos-2 cells revealed by an immunofluorescence method. PP1δ and nucleolin were also co-immunoprecipitated with anti-nucleolin and antiPP1δ antibodies. In the actinomycin D-treated cells, the subcellular localization of PP1δ and nucleolin was changed. Expression of PP1δ was upregulated with actinomycin D treatment. The level of 100-kD protein did not change in the actinomycin D-treated cells. However, the level of the 95-kD band increased with actinomycin D treatment. These results indicate that PP1δ was associated with nucleolin in the nucleolus of MG63 and Saos-2 cells and that nucleolin is a possible candidate substrate for PP1δ.

Original languageEnglish
Pages (from-to)1187-1193
Number of pages7
JournalJournal of Histochemistry and Cytochemistry
Issue number9
Publication statusPublished - Sept 2002
Externally publishedYes


  • Nucleolin
  • Osteoblast
  • Protein phosphatase

ASJC Scopus subject areas

  • Anatomy
  • Histology


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