Effects of protein kinase inhibitors on regeneration in vitro of adult frog sciatic sensory axons

Abstract

The effects of protein kinase inhibitors on regeneration in vitro of adult frog sciatic sensory axons were tested. Regeneration of crush-injured nerves for 8 days in serum-free medium was inhibited by staurosporine (100 nM) and H-7 (100 microM), which are both known to inhibit protein kinase C. With the use of a compartmented culture system it could be shown that H-7 exerted both local (outgrowth region) and central (ganglia) effects, the latter being more pronounced. The local effects could be due to reduction of Schwann cell proliferation by H-7. Immunohistochemistry demonstrated the presence of protein kinase C in neuronal cell bodies but not in axonal processes. Proliferation of Schwann cells was accompanied by increased protein kinase C immunoreactivity at the site of injury. H-7 caused a selective inhibition in the incorporation of radioactive phosphate into one 74 kDa protein of both ganglia and nerve but also a more general decrease in protein labelling. The results show that protein phosphorylations, possibly mediated by protein kinase C, are involved in regeneration-related mechanisms operating at both local and central levels in the adult frog sciatic sensory axons.

Synaptic activity‐related classical protein kinase C isoform localization in the adult rat neuromuscular synapse

“…Furthermore, PKC␣ and -␤II were detected in the postsynaptic and the Schwann cells. These results are in accordance with those of other studies that have also suggested immunoreactivity for PKC␣ and -␤II in the Schwann cells of sciatic nerves (Ekström et al, 1992;Roberts and McLean, 1997). It has been reported that PKC␥ is restricted mainly to the CNS and spinal cord (Nishizuka, 1995), and we found that it is almost absent from the NMJ and extrasynaptic muscle.…”

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

“…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). In isolated Schwann cell cultures maintained in serum-free defined medium, growth factors including platelet-derived growth factor (PDGF), basic fibroblast growth factor (bFGF), transforming growth factor-b (TGFb), and insulinlike growth factor 1 (IGF-1) stimulate Schwann cell growth when presented to cells in combination with agents that increase cAMP (Chen et al, 1991;Davis and Stroobant, 1990;Eccleston et al, 1990;Schumacher et al, 1993;Stewart et al, 1991).…”

蛋白激酶c调节脊髓神经元突起的生长

“…In addition, PKC can phosphorylate STAT3 at Ser727, which is phosphorylated primarily by JAK at Tyr705 [32] . In the contrast, inhibition of PKC has been found to decrease the axonal growth [3,5,6,11,34,35] . These findings indicate that PKC participates in nerve regeneration after nerve injury.…”

“…This rapid increase in axonal PKC expression occurs within hours after nerve injury and has been shown to co-stimulate axonal regeneration with other factors [23] . In contrast, inhibition of PKC has been found to inhibit the regenerative axonal growth [3,5,6,11,34,35] . Also, PKC enzymes are important signaling molecules in preventing neurodegeneration after the nervous system injury.…”