Demonstration of 2',3'-cyclic nucleotide 3'-phosphohydrolase in cultured human Schwann cells

Schwann cell cultures were established from adult human sural nerve biopsies. 2'3'-Cyclic nucleotide 3'-phosphohydrolase (CNPase) activity was estimated in the homogenates of those cells by a sensitive isotope assay using [3H]2',3'-cyclic AMP as substrate. A high level of CNPase activity was observed in cultured Schwann cells, whereas cultured human muscle and skin fibroblasts contained negligible levels of CNPase activity. CNPase of human Schwann cells followed typical enzyme-substrate kinetics, with an apparent Km of 1.6 mM for 2',3'-cyclic AMP, and the enzyme was stimulated by detergents such as Triton X-100 and deoxycholate. It was inhibited by p-chloromercuricbenzoate and 2'-AMP. These properties are typical of CNPase isolated from adult brain and spinal cord. CNPase can serve as a new biochemical marker of normal cultured human Schwann cells and can be useful in analyzing the properties of cultured Schwann cells from patients with dysschwannian neuropathies.