Synchronized onset of nuclear and cell surface modifications in U937 cells during apoptosis

  • E Bonanno Dipartimento di Biopatologia e Diagnostica per immagini, University of Rome Tor Vergata, Italy.
  • G Tagliafierro DIBISAA, University of Genoa, Italy.
  • EC Carlà Dipartimento di Scienze Biologiche e Ambientali e Tecnologia, University of Lecce;, Italy.
  • MR Montinari Dipartimento di Scienze Biologiche e Ambientali e Tecnologia, University of Lecce;, Italy.
  • P Pagliara Dipartimento di Scienze Biologiche e Ambientali e Tecnologia, University of Lecce, Italy.
  • G Mascetti X-Institute for Scientific Computing ltd, Genoa, Italy.
  • LG Spagnoli Dipartimento di Biopatologia e Diagnostica per immagini, University of Rome Tor Vergata, Italy.
  • L Dini | ldini@ilenic.unile.it CARSO Cancer Research Center, Italy.

Abstract

In this study we investigated the relationship between nuclear and cell surface modifications (i.e. blebbing, phosphatidylserine [PS] and sugar residues exposure) in a monocytic cell line, U937, during apoptosis induced by oxidative stress (1mM H2O2) or inhibition of protein synthesis (10 mg/ml puromycin). Dying cells were simultaneously observed for nuclear modifications, presence of superficial blebs and plasma membrane alterations. Morphological analysis performed by conventional fluorescence microscopy, or by transmission and scanning electron microscopy showed that the courses of nuclear and membrane alterations occured concomitantly, but the phenotype was dependent on the stage of the apoptotic process and the type of apoptogenic inducer used. The progression of apoptosis in U937 cells beyond early stages resulted in the extensive formation of blebs which concomitantly lost some typical markers of apoptosis, such as PS and sugar residues. Therefore, the modality by which the nucleus condenses, or the amount and the pattern of distribution of PS on the cell surface were, for each cell line, strictly related to the apoptogenic inducer. The morphological data reported in the present paper should lead to a more precise quantification of apoptosis by improving the detection of apoptotic cells in vivo (i.e. in tissue, organs), which is a crucial point in the evaluation of efficiency of antiproliferative drugs, such as antiblastic or immunosuppressive compounds.

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Published
2009-12-30
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How to Cite
Bonanno, E., Tagliafierro, G., Carlà, E., Montinari, M., Pagliara, P., Mascetti, G., Spagnoli, L., & Dini, L. (2009). Synchronized onset of nuclear and cell surface modifications in U937 cells during apoptosis. European Journal of Histochemistry, 46(1), 61-74. https://doi.org/10.4081/1655