Cytoskeletal Breakdown and Apoptosis Elicited by NO Donors in Cerebellar Granule Cells Require NMDA Receptor Activation

Abstract

We have recently demonstrated that nitric oxide (NO) donors can trigger either apoptosis or necrosis of neurons as a function of the intensity of the exposure. Here, we show that the apoptosis induced by the NO donors S-nitrosocysteine (SNOC) or S-nitroso-N-acetylpenicillamine (SNAP) in cultured cerebellar granule cells (CGCs) depends on NMDA receptor (NMDA-R) activation leading to intracellular Ca'+ overload. Early dissolution of actin filaments followed by breakdown of microtubUles and nuclear lam ins preceded the appearance of typical apoptotic features. NO donors induced tyrosine nitration in neurons, in a small population of contaminating astrocytes, and in cultures of cerebellar astroglial cells. However, astrocytes neither displayed cytoskeletal alterations nor underwent apoptosis. Competitive and uncompetitive NMDA receptor antagonists, such as Daminophosphonovaleric acid and MK-801, did not influence tyrosine nitration but prevented the accumulation of intracellular Ca", cytoskeletal breakdown, and apoptosis induced by either SNOC or SNAP in CGCs. Taken together, these data strongly suggest that Ca" influx through NMDA-R-gated ion channels is a critical event in CGC apoptosis induced by NO donors.