Stimulation by bovine lactoferrin of nerve growth factor synthesis/secretion in mouse L-M cells

Cultured mouse fibroblasts synthesize and secrete nerve growth factor (NGF). To learn the mechanism of action of an iron-binding protein, lactoferrin (Lf), on cultured animal cells, we have examined the effects of bovine Lf (bLf) on NGF synthesis/secretion in mouse L-M cells, a line derived from L929 fibroblast cells. Both apo- and holo-bLf induced an increase in NGF content in the cell-conditioned medium (CM) with similar effectiveness. Neither apo- nor holo- bovine transferrin (bTf) was effective, indicating that the observed induction of NGF production cannot be attributed to stimulation of iron transport. A basic peptide fragment of bLf (residues 17-41) isolated from a pepsin hydrolyzate of bLf was found to be effective for stimulation of NGF synthesis/secretion in L-M cells. This observation demonstrates that the basic nature of Lf is important for its interaction with fibroblast cells.