Interaction of protein phosphatase 1δ with nucleophosmin in human osteoblastic cells

Tatsuji Haneji, Jumpei Teramachi, Kanji Hirashima, Koji Kimura, Hiroyuki Morimoto

Research output: Contribution to journalArticlepeer-review

3 Citations (Scopus)

Abstract

Protien phosphorylation and dephosphrylation has been recognized as an essential mechanism in the regulation of cellular metabolism and function in various tissues. Serine and threonine protein phosphatases (PP) are divided into four categories: PP1, PP2A, PP2B, and PP2C. At least four isoforms of PP1 catalytic subunit in rat, PP1α, PP1γ1, PP1γ2, and PP1δ, were isolated. In the present study, we examined the localization and expression of PP1δ in human osteoblastic Saos-2 cells. Anti-PP1δ antibody recognized a protein present in the nucleolar regions in Saos-2 cells. Cellular fractionation revealed that PP1δ is a 37 kDa protein localized in the nucleolus. Nucleophosmin is a nucleolar phosphoprotein and located mainly in the nucleolus. Staining pattern of nucleophosmin in Saos-2 cells was similar to that of PP1δ. PP1δ and nucleophosmin were specifically stained as dots in the nucleus. Dual fluorescence images revealed that PP1δ and nucleophosmin were localized in the same regions in the nucleolus. Similar distribution patterns of PP1δ and nucleophosmin were observed in osteoblastic MG63 cells. The interaction of PP1δ and nucleophosmin was also shown by immunoprecipitation and Western analysis. These results indicated that PP1δ associate with nucleophosmin directly in the nucleolus and suggested that nucleophosmin is one of the candidate substrate for PP1δ.

Original languageEnglish
Pages (from-to)1-7
Number of pages7
JournalACTA HISTOCHEMICA ET CYTOCHEMICA
Volume45
Issue number1
DOIs
Publication statusPublished - 2012
Externally publishedYes

Keywords

  • Nucleophosmin
  • Osteoblast
  • Protein phosphatase

ASJC Scopus subject areas

  • Pathology and Forensic Medicine
  • Biochemistry
  • Physiology
  • Histology
  • Cell Biology

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