ROCK inhibition and CNTF interact on intrinsic signalling pathways and differentially regulate survival and regeneration in retinal ganglion cells.
Functional regeneration in the CNS is limited by lesion-induced neuronal apoptosis and an environment inhibiting axonal elongation. A principal, yet unresolved question is the interaction between these two major factors. We thus evaluated the role of pharmacological inhibition of rho kinase (ROCK), a key mediator of myelin-derived axonal growth inhibition and CNTF, a potent neurotrophic factor for retinal ganglion cells (RGC), in models of retinal ganglion cell apoptosis and neurite outgrowth/regeneration in vitro and in vivo. Here, we show for the first time that the ROCK inhibitor Y-27632 significantly enhanced survival of RGC in vitro and in vivo. In vitro, the co-application of CNTF and Y-27632 potentiated the effect of either substance alone. ROCK inhibition resulted in the activation of the intrinsic MAPK pathway, and the combination of CNTF and Y-27632 resulted in even more pronounced MAPK activation. While CNTF also induced STAT3 phosphorylation, the additional application of ROCK inhibitor surprisingly diminished the effects of CNTF on STAT3 phosphorylation. ROCK activity was also decreased in an additive manner by both substances. In vivo, both CNTF and Y-27632 enhanced regeneration of RGC into the non-permissive optic nerve crush model and additive effects were observed after combination treatment. Further evaluation using specific inhibitors delineate STAT3 as a negative regulator of neurite growth and positive regulator of cell survival, while MAPK and Akt support neurite growth. These results show that next to neurotrophic factors ROCK inhibition by Y-27632 potently supports survival of lesioned adult CNS neurons. Co-administration of CNTF and Y-27632 results in additive effects on neurite outgrowth and regeneration. The interaction of intracellular signalling pathways may, however, attenuate more pronounced synergy and has to be taken into account for future treatment strategies.
1Department of Neurology, Georg-August-University Göttingen, University Medicine, Waldweg 33, 37073 Göttingen, Germany. plingor@gwdg.de
Paul
P
Lingor
Lars
L
Tönges
Nicole
N
Pieper
Christina
C
Bermel
Elisabeth
E
Barski
Veronique
V
Planchamp
Mathias
M
Bähr
D000577:Amides / Q000494:pharmacology; D000818:Animals; D048429:Cell Size / Q000187:drug effects; D002470:Cell Survival / Q000187:drug effects; D002478:Cells, Cultured; D020934:Ciliary Neurotrophic Factor / Q000494:pharmacology*; D004357:Drug Synergism; D004791:Enzyme Inhibitors / Q000494:pharmacology; D005260:Female; D006801:Humans; D020929:Mitogen-Activated Protein Kinase Kinases / Q000502:physiology; D009409:Nerve Crush; D009416:Nerve Regeneration / Q000187:drug effects / Q000502:physiology*; D016501:Neurites / Q000187:drug effects / Q000502:physiology; D009900:Optic Nerve / Q000502:physiology; D051057:Proto-Oncogene Proteins c-akt / Q000502:physiology; D011725:Pyridines / Q000494:pharmacology; D051381:Rats; D017208:Rats, Wistar; D012160:Retina / Q000201:enzymology; D012165:Retinal Ganglion Cells / Q000187:drug effects / Q000502:physiology*; D050796:STAT3 Transcription Factor / Q000502:physiology; D015398:Signal Transduction / Q000187:drug effects / Q000502:physiology; D015854:Up-Regulation; D054460:rho-Associated Kinases / Q000037:antagonists & inhibitors / Q000378:metabolism / Q000502:physiology*
D000577:Amides; D020934:Ciliary Neurotrophic Factor; D004791:Enzyme Inhibitors; D011725:Pyridines; D050796:STAT3 Transcription Factor; C108830:Y 27632; D051057:Proto-Oncogene Proteins c-akt; D054460:rho-Associated Kinases; D020929:Mitogen-Activated Protein Kinase Kinases