ACTIVATION OF A NOVEL FORM OF PHOSPHOLIPASE-A - DURING LIVER-REGENERATION

Activation of phospholipase A(2) (PLA(2)) occurs following mitogenic s timulation Of cells, This study examined PLA(2) activation during live r regeneration. Increased activity was detected within 1 h after parti al hepatectomy, was maximal by 6 h, and returned to control levels by 24 h, Fractionation of cell-free extracts revealed multiple peaks of P LA(2) activity, One peak appeared identical to the previously describe d cPLA(2), and was modestly stimulated during regeneration, A higher m olecular weight form (hPLA(2)) was Stimulated similar to 5-fold during regeneration, This enzyme was Ca2+-dependent and selective for arachi donoylphosphatidylethanolamine, The activation of this novel form of P LA(2) represents an early event in liver regeneration, and is likely t o contribute to the proliferative response.