The ability of sensory axons to stimulate Schwann cell proliferation by contact was established in the 1970s. Although the mitogen responsible for this proliferation has been localized to the axon surface and biochemically characterized, it has yet to be identified. Recently a family of proteins known as heregulins (HRGs) has been isolated, characterized, and shown to interact with a number of class 1 receptor tyrosine kinases, including the erbB2, erbBS, and erbB4 gene products. These factors include glial growth factor, a Schwann cell mitogen. We have tested the effects of antibodies against components of this system (HRGβ1 and p185erB2) in cocultures of rat sensory neurons and human (or rat) Schwann cells to elucidate the role of these proteins in axon-induced Schwann cell proliferation. 2C4, a monoclonal antibody specific for the human p185erbB2 receptor tyrosine kinase, bound to the surface of human Schwann cells and reduced human Schwann cell incorporation of [3H]thymidine by >90% compared with untreated controls in this coculture system. This antibody had no effect on rat Schwann cell incorporation of [3H]thymidine under similar conditions. A polyclonal antibody raised against HRGβ1 reduced human and rat Schwann cell incorporation of [3H]thymidine by nearly 80% and up to 49%, respectively, relative to controls. These results imply that a HRG, or a HRG-like molecule, is a component of the axonal mitogen. This mitogen is presented to Schwann cells by axons and induces proliferation through an interaction that involves p185erbB2 on Schwann cells.
|Number of pages||5|
|Journal||Proceedings of the National Academy of Sciences of the United States of America|
|State||Published - Feb 28 1995|
ASJC Scopus subject areas