Cyclic AMP and calcium as potential mediators of stimulation of cultured Schwann cell proliferation by axolemma-enriched and myelin-enriched membrane fractions

Terminal complement complexes concomitantly stimulate proliferation and rescue of Schwann cells from apoptosis

“…Inhibition of PKC also prevented TCC-induced DNA synthesis. This still may be consistent with a G protein-mediated ERK signal-transduction scheme, because PKC 1) may be activated by G protein stimulation (for review, see Neer, 1994), 2) activates the ERK pathway through raf autophosphorylation (Marquardt et al, 1994), and 3) potentiates Schwann cell proliferation in response to other stimuli (Meador-Woodruff et al, 1984). Rapamycin, a p70 S6 kinase inhibitor (Chung et al, 1992), also inhibited TCC-induced DNA synthesis effectively in Schwann cells.…”

cAMP-dependent protein kinase A is required for Schwann cell growth: Interactions between the cAMP and neuregulin/tyrosine kinase pathways

“…Previous studies used crude GGF prepared from pituitary extract (Raff et al, 1978a) or crude neuronal membrane preparations (Meador-Woodruff et al, 1984;Ratner et al, 1984) to stimulate Schwann cell division and then assessed intracellular cAMP levels in the cells. These studies yielded conflicting results, possibly because cAMP levels were examined at different times after growth factor stimulation; none of the studies analyzed cAMP levels at 12 hr after growth factor stimulation, the time we find peak increases in cAMP levels.…”

“…Cyclic AMP may play an important role in these processes (Cassel et al, 1982;Meador-Woodruff et al, 1984;Raff et al, 1978a,b;Salzer and Bunge, 1980). Following nerve injury, the in vivo proliferation of adult Schwann cells is accompanied by cAMP accumulation at the injury site (Carlsen, 1982;Ekstrom et al, 1992).…”

Tissue Culture Studies of Schwann Cell Proliferation and Differentiation

“…Accentuation of the Schwann cell mitogenic response to axolem mal fragments by treatment of the cultures with phorbol esters, and inhibition of the mitogenic response by the calcium chelator citrate or the calmodulin antagonist triflu operazine suggest the possibility that cal cium, rather than cyclic AMP. mediates the Schwann cell mitogenic response to contact with axolemmal fragments [Meador- Woodruff et al, 1984], Cultured rat oligodendroglia and astroglia fail to demonstrate a proliferative response to axolemmal fragments. The very low rate of incorporation of tritiated thymidine into DNA by oligodendroglia prepared from 18-day-old rats is not altered by addition of axolemmal fragments to the medium [Sobue et al, 1983], and axolemmal fragments in duce a marked and consistent inhibition of proliferation of cultured neonatal rat astro glia [Sobue and Pleasure, 1984b].…”