Apoptotic cells selectively uptake minor glycoforms of vitronectin from serum

• Type: Article in International Scientific Journal
• Date: 2013

Authors

Malagolini, N (Author) Other; Catera, M (Author) Other; Osorio, H (Author) FMUP; Celso Reis (Author) ICBAS; Chiricolo, M (Author) Other; Dall'Olio, F (Author) Other

Journal

Title: APOPTOSIS

Vol. 18

Pages: 373-384

ISSN: 13608185

Publisher: Springer Nature

Indexing

ISI Web of Knowledge - 4 Citations

Scopus - 4 Citations

Other information

Authenticus ID: P-005-2A9

DOI: 10.1007/s10495-013-0812-z

Abstract (EN): Apoptosis profoundly alters the carbohydrate layer coating the membrane of eukaryotic cells. Previously we showed that apoptotic cells became reactive with the alpha 2,6-sialyl-specific lectin from Sambucus nigra agglutinin (SNA), regardless of their histological origin and the nature of the apoptotic stimulus. Here we reveal the basis of the phenomenon by showing that in apoptotic cancer cell lines SNA reactivity was mainly associated with a 67 kDa glycoprotein which we identified by MALDI-TOF/TOF and immunoblot analysis as bovine vitronectin (bVN). bVN was neither present in non-apoptotic cells, nor in cells induced to apoptosis in serum-free medium, indicating that its uptake from the cell culture serum occurred only during apoptosis. The bVN molecules associated with apoptotic cancer cell lines represented minor isoforms, lacking the carboxyterminal sequence and paradoxically containing a few alpha 2,6-linked sialic acid residues. Despite their poor alpha 2,6-sialylation, these bVN molecules were sufficient to turn apoptotic cells to SNA reactivity, which is a late apoptotic event occurring in cells positive to both annexin-V and propidium iodide. Unlike in cancer cell lines, the major bVN form taken up by apoptotic neutrophils and mononuclear cells was a 80 kDa form. In apoptotic SW948 cells we also detected the alpha 2,6-sialylated forms of the stress-70 mitochondrial precursor (mortalin) and of tubulin-beta 2C. These data indicate that the acquisition of vitronectin isoforms from the environment is a general, although cell specific phenomenon, potentially playing an important role in post-apoptotic events and that the alpha 2,6-sialylation of intracellular proteins is a new kind of posttranslational modification associated with apoptosis.

Language: English

Type (Professor's evaluation): Scientific

No. of pages: 12