beta-Nerve growth factor (beta NGF) receptors on glial cells. Cell-cell interaction between neurones and Schwann cells in cultures of chick sensory ganglia

Abstract

Receptors for beta-nerve growth factor (beta NGF), so far regarded as specific cell surface markers of certain peripheral neurones, were found to be expressed on cultured non-neuronal cells of chick embryo dorsal root ganglia (drg) (Kd beta NGF = 2 X 10(-9) M). Autoradiography revealed that binding of [125I] beta NGF was restricted to a subpopulation of the non-neuronal drg cells. Cultured embryonic skin fibroblasts, liver cells, gut cells, muscle fibroblasts, myoblasts, and myotubes, as well as macrophages and the cell lines 3T3, 3T3SV40, BHK, BHK Py, PCC3 and ND1, did not express receptors for beta NGF. Non-neuronal drg cells obtained by a procedure designed for the preparation of pure Schwann cells, as well as RN6 Schwannoma cells, were beta NGF receptor positive. The beta NGF receptor-positive non-neuronal drg cells displayed behaviour typical of Schwann cells in their interaction with drg neurones in single cell, as well as explant cultures. Three stages of neurone-Schwann cell interaction were discernible: (1) association--neurites preferentially grew over beta NGF receptor-positive non-neuronal cells; (2) cell division/alignment--beta NGF receptor-positive non-neuronal cells were induced to proliferate and aligned and elongated along neurites; (3) ensheathment--the outline of beta NGF receptor-positive non-neuronal cells and neurites merged. In drg cell cultures prepared from embryonic stages E6-E10, 25-40% of the non-neuronal cells were beta NGF receptor-positive. Later in development, from E12 onward, less than or equal to 1% of the cultured non-neuronal cells expressed beta NGF receptors.