The effects of nerve growth factor on acetylcholinesterase and its multiple forms in cultures of rat PC12 pheochromocytoma cells: Increased total specific activity and appearance of the 16 S molecular form

Abstract

The effects of nerve growth factor (NGF) on acetylcholinesterase (AChE) activity and the distribution of this enzyme among its different molecular forms were studied in monolayer cultures of rat PC12 pheochromocytoma cells. It has been previously shown that PC12 cells respond to NGF by ceasing cell division and extending long, branching neurites. In NGF-untreated cultures, the specific activity of AChE was constant over a wide range of cell densities. By 4 days of NGF treatment there was a threefold increase in the activity of AChE per milligram protein. Analysis of the multiple molecular forms of AChE by sucrose gradient sedimentation revealed the 4, 6.5, and 10 S forms of the enzyme in NGF-untreated cultures. After 3 days of exposure to NGF, the 16 S form of the enzyme became apparent; by 7–10 days of treatment this form reached maximal levels (2–3% of total AChE activity). In spinner-suspension cultures, in which PC12 cells do not attach to a substrate and cannot grow neurites, NGF treatment yielded an increase in specific activity of AChE, but did not induce the 16 S form of the enzyme.