Characterization of a β-nerve growth factor expression vector for mammalian cells

A mammalian expression vector that directs expression of murine β-nerve growth factor (β-NGF) from a murine sarcoma virus long terminal repeat (LTR) promoter element was constructed and characterized. The vector, designated pLTRSNGF, was stably transfected into murine L-cells, and β-NGF mRNA and protein levels were quantified and compared to endogenous levels in control L-cells. Transfection of pLTRSNGF resulted in an approximate doubling of both β-NGF mRNA and mature β-NGF protein secreted into the media. Transfection of pLTRSNGF into rat PC 12 cells resulted in colonies of autocrine-differentiating cells that extended dense networks of neurites in the absence of added NGF, indicating that the β-NGF produced from the vector is biologically active.