NAD-dependent inhibition of the NAD-glycohydrolase activity in A549 cells.

Enrico Balducci, Luigi G Micossi

Index: Mol. Cell Biochem. 233 , 127-132, (2002)

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Abstract

NAD glycohydrolases are enzymes that catalyze the hydrolysis of NAD to produce ADP-ribose and nicotinamide. Regulation of these enzymes has not been fully elucidated. We have identified a NAD-glycohydrolase activity associated with the outer surface of the plasma membrane in human lung epithelial cell line A549. This activity is negatively regulated by its substrate beta-NAD but not by alpha-NAD. Partial restoration of NADase activity after incubation of the cells with arginine or histidine, known ADP-ribose acceptors, suggests that inhibition be regulated by ADP-ribosylation. A549 do not undergo to apoptosis upon NAD treatment indicating that this effect be likely mediated by a cellular component(s) lacking in epithelial cells.