The neuron–glia signal β‐neuregulin promotes Schwann cell motility via the MAPK pathway

Abstract

Neuregulins constitute a family of related growth factors that play important roles in Schwann cell development and maturation. We investigated the involvement of beta-neuregulin in Schwann cell migration, using a simple in vitro bioassay. Pure Schwann cells were prepared from the sciatic nerves of 5-day-old rats and were grown in defined medium, with or without serum, until a monolayer of confluent cells was formed. A cell-free area was then generated by inflicting a scratch resulting in a 1-mm-wide gap. Schwann cell migration within the gap was monitored microscopically at given time intervals and was quantified using an image analysis system. The extent of cell proliferation was estimated by BrdU incorporation, and cell migration was quantified both in the absence and presence of cytosine arabinoside. We found that, in the absence of serum, beta-neuregulin at a dose submaximal for proliferation increased the rate of Schwann cell migration by 84%. A more moderate effect was observed when beta-neuregulin was applied in the presence of serum which, however, is by itself responsible for increased Schwann cell motility. To assess the signal transduction pathways involved in this procedure we used one inhibitor of MAPK, PD098059, two inhibitors of PI-3-kinase, wortmannin, and LY0294002, and three different PKC inhibitors. Of these PD098059 inhibited the neuregulin-induced enhancement in Schwann cell migration by 40%, the two PI-3-kinase inhibitors yielded an approximately 20% inhibition while the PKC inhibitors were ineffective. Our data indicate that the action of beta-neuregulin on Schwann cell motility is primarily mediated via the MAPK pathway.

P2X7-mediated Increased Intracellular Calcium Causes Functional Derangement in Schwann Cells from Rats with CMT1A Neuropathy

“…Migration Assay-To test the ability of CMT1A SC to migrate after the P2X7 receptor siRNA-specific suppression or inhibition by the use of P2X7 receptor inhibitor KN-62, we followed a published protocol (8,16). In P2X7 down-regulation experiments by specific siRNA, SC were electroporated in the absence of siRNA oligos UT or transfected with P2X7-targeting Stealth TM siRNA (Invitrogen).…”

“…The extent of cell migration was assessed by subtracting the average gap width at T 1 from the average gap width at T 0 . SC migration was monitored for a maximum of 12 h to avoid interference in the evaluation because of SC proliferation (16). Assessment of migration distance was performed on 10 SC cultures for each condition, using the Image Pro-Plus Software (Immagini e Computer, Rho, Milan, Italy).…”

Adenosine: an activity-dependent axonal signal regulating MAP kinase and proliferation in developing Schwann cells

“…The ERK/MAPK pathway plays a central role in regulating growth factor-dependent proliferation and differentiation of most mammalian cells, including developing SCs (Maurel and Salzer, 2000;Meintanis et al, 2001). Growth factors such as PDGF and neuregulins signal through the Ras/Raf/MAPK pathway to regulate cell-cycle progression in SCs (Kim et al, 1997a;Kim et al, 2001b;Maurel and Salzer, 2000), but the effect of adenosine on ERK/MAPK signaling in SCs has not been explored previously.…”

Neuregulin-1 Enhances Motility and Migration of Human Astrocytic Glioma Cells

“…In the peripheral nervous system, NRG-1 was shown to enhance the motility of Schwann cells (57). One study reported that this function was dependent upon the activation of the mitogen-activated protein kinase cascade (58). In addition, Vartanian et al (38) demonstrated that NRG-1 could induce the rapid association of FAK with erbB2 and erbB3 in cultured Schwann cells.…”