Activation of a novel form of phospholipase A2 during liver regeneration

Activation of phospholipase A2 (PLA2) occurs following mitogenic stimulation of cells. This study examined PLA2 activation during liver regeneration. Increased activity was detected within 1 h after partial hepatectomy, was maximal by 6 h, and returned to control levels by 24 h. Fractionation of cell-free extracts revealed multiple peaks of PLA2 activity. One peak appeared identical to the previously described cPLA2, and was modestly stimulated during regeneration. A higher molecular weight form (hPLA2) was stimulated approximately 5-fold during regeneration. This enzyme was Ca(2+)-dependent and selective for arachidonoylphosphatidylethanolamine. The activation of this novel form of PLA2 represents an early event in liver regeneration, and is likely to contribute to the proliferative response.