The intranuclear amount of phospholipase C β1 decreases following cell differentiation in Friend cells, whereas γ1 isoform is not affected

N. Zini, A. Ognibene, S. Marmiroli, A. Bavelloni, M. C. Maltarello, I. Faenza, A. Valmori, N. M. Maraldi

Research output: Contribution to journalArticlepeer-review


The existence of a signal transduction system in the nucleus, based on polyphosphoinositide breakdown mediated by specific phosphoinositidases (PLC), has been widely documented. In different cell systems, nuclear PLCs can be modulated, in response to agonists, either by enhancing or by down-regulating their activity, thus leading to DNA replication or to cell differentiation. Friend cells, induced to erythroid differentiation by dimethyl sulfoxide (DMSO), show a down-regulation of PLC β1 isoform, as indicated by the reduction of the transcription of its mRNA and of the in vitro synthesis of its translation product. The intracellular localization and the amount of different PLC isoforms have been evaluated by electron microscope immunocytochemistry. In untreated Friend cells, PLC β1 and γ1 isoforms are both present within the nucleus, whereas mainly the γ1 isoform is detected in the cytoplasm. The small amount of cytoplasmic PLC β1 is probably representative only of the newly synthesized enzyme. Quantitative immunolabeling analyses demonstrate that erythroid differentiation is associated with a significant decrease of the PLC β1 amount in the nucleus and with an almost complete disappearance of that isoform in the cytoplasm, whereas the PLC γ1 isoform is unaffected. The two PLC isoforms, moreover, appear to be differently associated with the nuclear components, PLC β1 being steadily bound to the inner nuclear matrix, whereas PLC γ1 is almost completely soluble.

Original languageEnglish
Pages (from-to)25-34
Number of pages10
JournalEuropean Journal of Cell Biology
Issue number1
Publication statusPublished - 1995


  • Friend cells
  • Immunocytochemistry
  • Nuclear matrix
  • Nuclear signal transduction
  • PLC isoforms

ASJC Scopus subject areas

  • Anatomy
  • Cell Biology

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