Abstract

The function of PML in apoptosis was elucidated in human B lymphocyte- derived cell line. For this purpose, the number of the PML focus and the percentage of apoptotic cells were determined periodically with immunofluorescent staining after 60Coγ-ray or γ-interferons (γ-IFN) treatment. On irradiation with 60Coγ-ray or treatment with γ-IFN, PML protein was over-expressed. This was measured from PML foci, which peaked at 72 hr and 24 hr, respectively. The B-cell line also contained a greater proportion of apoptotic cells after the treatments. The strongest induction of apoptosis both by 60Co-γ ray irradiation and by γ-IFN treatment was observed 24 hr later than the induction of PML expression. In addition, γ- rays-induced apoptosis and PML expression were mediated through caspase-8 but not through caspase-3. However, caspase-8 was involved in γ-IFN-induced PML expression and apoptosis. While caspase-3 is involved solely in PML expression, and partially in apoptosis. These results suggest that 60Co-γ ray irradiation or γ-IFN treatment can induce PML protein expression and apoptosis in the B-cell line as caspase-3 dependently or independently. Key words: PML Protein, Apoptosis, 60Co-γ ray, γ-IFN, Caspase activation.

Highlights

  • B-cell line contained a greater proportion of normal epithelial cells

  • The analysis showed that apoptosis. These results suggest that the apoptosis and promyelocytic leukemia (PML) expression induced by γ-ray irradiation are mediated through caspase-8, but not through caspase-3

  • PML protein belongs to a new family of zinc finger DNA-binding transcription factors (Berg, 1990; Freemont et al, 1991) and exhibits a speckled nuclear localization on immunofluorescence microscopy in acute promyelocytic leukemia (APL) cells (Daniel et al, 1993; Kastner, et al, 1992)

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Summary

Introduction

B-cell line contained a greater proportion of normal epithelial cells Expression and apoptosis: The effect of caspase-3 and -8 inhibitors on the PML expression and apoptosis induced by γ-ray irradiation or γ-IFN treatment in the PML protein expression and apoptosis induced by γ-IFN, responded differently to both inhibitors

Results
Conclusion

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