Acylphosphatase is a strong apoptosis inducer in HeLa cell line

Acylphosphatase (AcP) is a low-molecular-weight protein widely distributed in many vertebrate tissues with a yet unknown physiologic function. To study the in vivo behavior of AcP, HeLa cells were transiently transfected with a vector expressing the AcP/EGFP fusion protein. Analysis of the transfected cells showed a high level of cellular death in cells expressing the AcP/EGFP fusion protein with respect to control cells expressing EGFP alone. Flow cytometry and time lapse analysis of AcP/EGFP transfected cells evidenced a typical pattern of apoptosis. Surprisingly, cells transfected with a mutated form of AcP, with negligible in vitro acylphosphatase activity, undergo apoptosis as well as cells transfected with wild-type protein, suggesting that the physiologic role of AcP could be not related to this catalytic activity.