title: Calcitonin gene-related peptide promotes Schwann cell proliferation.
abstract: Schwann cells in culture divide in response to defined mitogens such as PDGF and glial growth factor (GGF), but proliferation is greatly enhanced if agents such as forskolin, which increases Schwann cell intracellular cAMP, are added at the same time as PDGF or GGF (Davis, J. B., and P. Stroobant. 1990. J. Cell Biol. 110:1353-1360). The effect of forskolin is probably due to an increase in numbers of PDGF receptors (Weinmaster, G., and G. Lemke. 1990. EMBO (Eur. Mol. Biol. Organ.) J. 9:915-920. Neuropeptides and beta-adrenergic agonists have been reported to have no effect on potentiating the mitogenic response of either PDGF or GGF. We show that the neuropeptide calcitonin gene-related peptide (CGRP) increases Schwann cell cAMP levels, but the cells rapidly desensitize. We therefore stimulated the cells in pulsatile fashion to partly overcome the effects of desensitization and show that CGRP can synergize with PDGF to stimulate Schwann cell proliferation, and that CGRP is as effective as forskolin in the pulsatile regime. CGRP is a good substrate for the neutral endopeptidase 24.11. Schwann cells in vivo have this protease on their surface, so the action of CGRP could be terminated by this enzyme and desensitization prevented. We therefore suggest that CGRP may play an important role in stimulating Schwann cell proliferation by regulating the response of mitogenic factors such as PDGF.
authors.affiliation: Medical Research Council Laboratory for Molecular Cell Biology, University College London, United Kingdom.
authors.forename: L
authors.initials: L
authors.lastname: Cheng
authors.forename: M
authors.initials: M
authors.lastname: Khan
authors.forename: A W
authors.initials: AW
authors.lastname: Mudge
mesh_terms: D000818:Animals; D015740:Calcitonin Gene-Related Peptide / Q000494:pharmacology*; D002455:Cell Division / Q000187:drug effects; D002469:Cell Separation; D002478:Cells, Cultured; D005576:Colforsin / Q000494:pharmacology; D000242:Cyclic AMP / Q000378:metabolism; D004305:Dose-Response Relationship, Drug; D004357:Drug Synergism; D005347:Fibroblasts; D007545:Isoproterenol / Q000494:pharmacology; D008938:Mitosis / Q000187:drug effects; D015260:Neprilysin / Q000378:metabolism; D010982:Platelet-Derived Growth Factor / Q000494:pharmacology; D051381:Rats; D012583:Schwann Cells / Q000187:drug effects* / Q000201:enzymology / Q000378:metabolism; D012584:Sciatic Nerve / Q000166:cytology
chemical_list: D010982:Platelet-Derived Growth Factor; D005576:Colforsin; D000242:Cyclic AMP; D015260:Neprilysin; D015740:Calcitonin Gene-Related Peptide; D007545:Isoproterenol