O-acetylation of GD3 prevents its apoptotic effect and promotes survival of lymphoblasts in childhood acute lymphoblastic leukaemia

Mukherjee, Kankana ; Chava, Anil Kumar ; Mandal, Chandan ; Dey, Sailendra Nath ; Kniep, Bernhard ; Chandra, Sarmila ; Mandal, Chitra (2008) O-acetylation of GD3 prevents its apoptotic effect and promotes survival of lymphoblasts in childhood acute lymphoblastic leukaemia Journal of Cellular Biochemistry, 105 (3). pp. 724-734. ISSN 0730-2312

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Official URL: http://onlinelibrary.wiley.com/doi/10.1002/jcb.218...

Related URL: http://dx.doi.org/10.1002/jcb.21867

Abstract

We have previously demonstrated induction of O-acetylated sialoglycoproteins on lymphoblasts of childhood acute lymphoblastic leukaemia (ALL). These molecules promote survival of lymphoblasts by preventing apoptosis. Although O-acetylated sialoglycoproteins are over expressed, the status of O-acetylation of gangliosides and their role in lymphoblasts survival remains to be explored in ALL patients. Here, we have observed enhanced levels of 9-O-acetylated GD3 (9-O-AcGD3) in the lymphoblasts of patients and leukaemic cell line versus disialoganglioside GD3 in comparison to the normal cells. Localization of GD3 and 9-O-AcGD3 on mitochondria of patient's lymphoblasts has been demonstrated by immuno-electron microscopy. The exogenous administration of GD3-induced apoptosis in lymphoblasts as evident from the nuclear fragmentation and sub G0/G1 apoptotic peak. In contrast, 9-O-AcGD3 failed to induce such apoptosis. We further explored the mitochondria-dependent pathway triggered during GD3-induced apoptosis in lymphoblasts. GD3 caused a time-dependent depolarization of mitochondrial membrane potential, release of cytochrome c and 7.4- and 8-fold increased in caspase 9 and caspase 3 activity respectively. However, under identical conditions, an equimolar concentration of 9-O-AcGD3 failed to induce similar effects. Interestingly, 9-O-AcGD3 protected the lymphoblasts from GD3-induced apoptosis when administered in equimolar concentrations simultaneously. In situ de-O-acetylation of 9-O-AcGD3 with sodium salicylate restores the GD3-responsiveness to apoptotic signals. Although both GD3 and 9-O-acetyl GD3 localize to mitochondria, these two structurally related molecules may play different roles in ALL-disease biology. Taken together, our results suggest that O-acetylation of GD3, like that of O-acetylated sialoglycoproteins, might be a general strategy adopted by leukaemic blasts towards survival in ALL.

Item Type:Article
Source:Copyright of this article belongs to John Wiley & Sons, Inc.
Keywords:Acute Lymphoblastic Leukaemia (ALL); GD3; 9-O-acetyl GD3 (9-O-AcGD3); Mitochondrial Membrane Potential; Cytochrome c; Caspase 9; Apoptosis
ID Code:19319
Deposited On:23 Nov 2010 13:09
Last Modified:28 Feb 2011 08:58

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