PERIPHERIN EXPRESSION IN HIPPOCAMPAL-NEURONS INDUCED BY MUSCLE SOLUBLE FACTOR(S)

Previous studies have shown that neuronal cells in culture can switch neurotransmitters when grown in, the presence of different target cell s. To examine whether this plasticity extends to structural proteins, we cocultured hippocampal neurons and pituitary-derived neuroendocrine (AtT20) cells with astrocytes, kidney epithelial cells, or skeletal m uscle cells. As a marker of phenotypic change we used the cytoskeletal protein peripherin, a type III intermediate filament (IF) subunit whi ch is not expressed in hippocampal neurons and AtT20 cells. We show he re that soluble factor(s) secreted specifically from skeletal muscle c ells can induce the expression and de novo assembly of peripherin in a subset of post-mitotic neurons. We further demonstrate that one of th ese factors is the Leukemia Inhibitory Factor/Cholinergic Neuronal Dif ferentiation Factor. The environmentally regulated expression of perip herin implies a remarkable degree of plasticity in the cytoskeletal or ganization of postmitotic CNS cells and provides a noninvasive model s ystem to examine the de novo assembly of IF proteins under in vivo con ditions.